bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toughness and the existence of k‐factors
Authors: Enomoto Hikoe , Jackson Bill , Katerinis P. , Saito Akira 
Published: May 2007

AbstractA connected graph G is called t‐tough if t · w(G ‐ S) ⩽ |S| for any subset S of V(G) with w(G ‐ S) > 1, where w(G ‐ S) is the number of connected components of G ‐ S. We prove that every k‐tough graph has a k‐factor if k|G| is even and |G| ⩾ k + 1. This result, first conjectured by Chvátal, is sharp in the following sense: For any positive integer k and for any positive real number ε, there exists a (k ‐ ε)‐tough graph G with k|G| even and |G| ⩾ k + 1 which has no k‐factor.
Orthogonal one‐factorization graphs
Authors: Dinitz Jeffrey H. 
Published: May 2007

AbstractAn orthogonal one‐factorization graph (OOFG) is a graph in which the vertices are one‐factorizations of some underlying graph H, and two vertices are adjacent if and only if the one‐factorizations are orthogonal. An arbitrary finite graph, G, is realizable if there is an OOFG isomorphic to G. We show that every finite graph is realizable as an OOFG with underlying graph Kn for some n. We also discuss some special cases.
On the size of graphs with complete‐factors
Authors: Akiyama Jin , Frankl Peter 
Published: May 2007

AbstractA spanning subgraph H of a graph G is called a Kl‐factor if each component of H is isomorphic to the complete graph of order l. We determine the minimum size for any graph to have a Kl‐factor. Relating this result, we give a new short proof of the Erdös‐Gallai theorem on the maximum size of graphs with at most β independent edges.
Chromaticity of two‐trees
Authors: Whitehead Earl Glen 
Published: May 2007

AbstractThe graphs called 2‐trees are defined by recursion. The smallest 2‐tree is the complete graph on 2 vertices. A 2‐tree on n + 1 vertices (where n ≥ 2) is obtained by adding a new vertex adjacent to each of 2 arbitrarily selected adjacent vertices in a 2‐tree on n vertices. A graph G is a 2‐tree on n(≥2) vertices if and only if its chromatic polynomial is equal to γ(γ ‐ 1)(γ ‐ 2)n—2.
Edge‐disjoint spanning trees: A connectedness theorem
Authors: Farber M. , Richter B. , Shank H. 
Published: May 2007

AbstractIt is well known that any spanning tree of a graph can be obtained from any other by a sequence of single edge exchanges in a way that preserves, at each step, the property of being a spanning tree. We consider a variation of this problem concerning pairs of edge‐disjoint spanning trees. In particular, it is shown that any pair of edge‐disjoint spanning trees can be obtained from any other by a sequence of single edge exchanges in a way that preserves, at each step, the property of being edge‐disjoint spanning trees.
On some minimal graphs of the torus
Authors: Bodendiek R. , Wagner K. 
Published: May 2007

AbstractLet Γ be the set of finite, simple and nondirected graphs being not embeddable into the torus. Furthermore let >4 be a partial order‐relation and M4 (Γ) the minimal basis of Γ. In this paper we determine three graphs of M4 (Γ) being embeddable into the projective plane and containing the subgraph W.
On Stockmeyer's non‐reconstructible tournaments
Authors: Kocay William L. 
Published: May 2007

AbstractStockmeyer (The falsity of the reconstruction conjecture for tournaments. J. Graph Theory, 1 (1977) 19–25) constructed an infinite family of non‐reconstructible tournaments. It has been known for some time that there is a flaw in the proof given there. We provide an alternative constructive proof which is much simpler than the original proof.
Bichromaticity of bipartite graphs
Authors: Pritikin Dan 
Published: May 2007

AbstractLet B be a bipartite graph with edge set E and vertex bipartition M, N. The bichromaticity β(B) is defined as the maximum number β such that a complete bipartite graph on β vertices is obtainable from B by a sequence of identifications of vertices of M or vertices of N. Let μ = max{∣M∣, ∣N∣}. Harary, Hsu, and Miller proved that β(B) ≥ μ + 1 and that β(T) = μ + 1 for T an arbitrary tree. We prove that β(B) ≤ μ + ∣E∣/μ yielding a simpler proof that β(T) = μ + 1. We also characterize graphs for which Kμ, 2 is obtainable by such identifications. For QK. the graph of the K‐dimensional cube, we obtain the inequality 2K−1 + 2 ≤ β(QK) ≤ 2K−1 + K, the upper bound attainable iff K is a power of 2.
Existence of spanning and dominating trails and circuits
Authors: Veldman H. J. 
Published: May 2007

AbstractLet T be a trail of a graph G. T is a spanning trail (S‐trail) if T contains all vertices of G. T is a dominating trail (D‐trail) if every edge of G is incident with at least one vertex of T. A circuit is a nontrivial closed trail. Sufficient conditions involving lower bounds on the degree‐sum of vertices or edges are derived for graphs to have an S‐trail, S‐circuit, D‐trail, or D‐circuit. Thereby a result of Brualdi and Shanny and one mentioned by Lesniak‐Foster and Williamson are improved.
A separation property of planar triangulations
Authors: Diestel Reinhard 
Published: May 2007

AbstractEvery planar triangulation G has the property that each induced cycle C of length at least 4 in G separates G, but no proper subgraph of C does. This property is trivially shared by all chordal graphs since these contain no such cycles at all. We ask to what extent maximally planar graphs and chordal graphs are unique with this property — or how much larger the class of graphs is that it determines. The answer is given in the form of a characterization of this class in terms of the simplicial decompositions of its elements. The theory of simplicial decompositions appears to be a very interesting, but still largely unexploited, method of characterization in graph theory, which seems tailor‐made for problems like the one discussed.
Contractibility and NP‐completeness
Authors: Brouwer A. E. , Veldman H. J. 
Published: May 2007

AbstractFor a fixed graph H, let H‐CON denote the problem of determining whether a given graph is contractible to H. The complexity of H‐CON is studied for H belonging to certain classes of graphs, together covering all connected graphs of order at most 4. In particular, H‐CON is NP‐complete if H is a connected triangle‐free graph other than a star. For each connected graph H of order at most 4 other than P4 and C4, H‐CON is solvable in polynomial time.
On generalized graph colorings
Authors: Brown Jason I. , Corneil Derek G. 
Published: May 2007

AbstractGiven a property P, graph G, and k ⩾ 0, a P k‐coloring is a function π: V(G) → {1, …, k} such that the subgraph induced by each color class has property P; χ(G : P) is the least k, for which G has a P k‐coloring. We investigate here the theory of P colorings. Generalizations of the wellknown notions of vertex criticality and unique colorability are discussed, and we extend a theorem of Erdös to P chromatic graphs.
Minimum path decompositions of oriented cubic graphs
Authors: Reid K. B. , Wayland Keith 
Published: May 2007

AbstractPullman [3] conjectured that if k is an odd positive integer, then every orientation of a regular graph of degree k has a minimum decomposition which contains no vertex which is both the initial vertex of some path in the decomposition and the terminal vertex of some other path in the decomposition. In this paper, the conjecture is established for cubic graphs, and its connection with Kelly's conjecture for tournaments is described.
Time‐lagged effects of spring Tibetan Plateau soil moisture on the monsoon over China in early summer
Authors: Chow K. C. , Chan Johnny C. L. , Shi Xueli , Liu Yiming , Ding Yihui 
Published: May 2007

AbstractThe objective of the present study is to investigate the effect of initial soil moisture in the Tibetan Plateau (ISMTP) during the spring period on the local and regional climate in subsequent months. Numerical experiments with different ISMTP are made from 1 April to 30 June for the year 1998 using a regional climate model. This was a wet year with anomalously high summer precipitation over China. The same experiments have also been done for the year 1995, which was a normal year with respect to the summer rainfall over China. In both years, the snow amount over the Tibetan Plateau (TP) was higher than normal in the preceding winter/spring. The results of the experiments indicated that an increase in the ISMTP may lead to decreases in the air temperature, vertical velocity, and surface heating over the TP in June. In addition to the local effects, an increase in the ISMTP may also lead to modifications of the climate in some remote regions in early summer, such as an increase in the amount of monsoon precipitation over the mid to lower reaches of the Yangtze River region in eastern China and a decrease over the south China region. These precipitation differences due to the changes in ISMTP are consistent with those due to anomalous snow cover over the TP in winter or spring. Physically, the Tibetan High is weakened with an increase in ISMTP, which leads to a change in the strength of the Asian summer monsoon. Copyright © 2007 Royal Meteorological Society
Time variations of the effects of circulation variability modes on European temperature and precipitation in winter
Authors: Beranová Romana , Huth Radan 
Published: May 2007

AbstractFive modes of variability are identified in winter monthly mean 500 hPa heights over the Euro‐Atlantic sector by rotated principal component analysis. Time variations of the effects of the modes on temperature and precipitation at more than 100 European stations are examined for period 1958–1998. Time variations are investigated by running correlations with the 15‐year window. At most of the stations, the correlations with circulation patterns vary considerably in time, both for temperature and precipitation. The spatial structure of the variations is assessed by cluster analysis of time variations of correlations. The groupings together with changes in the intensity and position of the circulation modes suggest possible mechanisms of the time variations in the circulation‐to‐climate effects. Copyright © 2007 Royal Meteorological Society
Evidence of plaggen soils in European North Russia (Arkhangelsk region)
Authors: Hubbe Alicja , Chertov Oleg , Kalinina Olga , Nadporozhskaya Marina , Tolksdorf‐Lienemann Eva , Giani Luise 
Published: May 2007

AbstractTo clarify whether a particular group of soils of Archangelsk region (European N Russia) with humus‐rich topsoils exceeding the plowing zone supports an anthropogenic formation, four exemplary profiles were investigated. The investigation sites are characterized by distinct elevated surfaces, and the soils show thick toplayers of up to 60 cm with enrichment of soil organic matter and artifacts like brick, charcoal, and peat fragments, all indicating an anthropogenic origin. Increased phytolith amounts and high P contents of up to 800 mg kg–1 citric acid–soluble P and up to 1,400 mg kg–1 total P in the top horizons support an anthropogenic influence. These properties are very similar to the Plagganthrepts of NW Europe. The same is true regarding the main management aims: increasing soil fertility and overcoming the need of bedding materials. Having the required depths of the anthropogenic topsoil, the properties of the soils of the Archangelsk region allow a classification as Agrozems (Russian classification), Plaggenesche (German classification), and Plagganthrepts (US taxonomy). Since the high base saturation of the topsoil excludes a designation as plaggic horizon, the topsoil has to be considered as terric horizon, which leads to a classification as Terric Anthrosol according to WRB.
Salinity‐induced changes in growth, superoxide dismutase activity, and ion content of two olive cultivars
Authors: Goreta Smiljana , Bučević‐Popović Viljemka , Pavela‐Vrančić Maja , Perica Slavko 
Published: May 2007

AbstractOlive trees (Olea europaea L.) are considered moderately tolerant to salinity, with clear differences found among cultivars. One‐year‐old self‐rooted olive plants of the Croatian cv. Oblica and Italian cv. Leccino were grown for 90 d in nutrient solutions containing 0, 66, or 166 mM NaCl, respectively. The shoot length and the number of nodes and leaves for both cultivars were not affected by salinity up to 66 mM NaCl. However, at 166 mM NaCl, growth of Leccino was reduced earlier and to a higher extent than growth of Oblica. After 10 d of exposure to 66 and 166 mM NaCl, increased activity of superoxide dismutase (SOD) was observed in Leccino, whereas there was almost no response in Oblica. Reduced SOD activity in Leccino at 166 mM NaCl was observed after prolonged stress (90 d), whereas in Oblica SOD was increased at 66 mM compared to control or 166 mM NaCl. Electrolyte and K+ leakage were increased and relative water content decreased as NaCl concentration increased with similar intensity of response measured in both cultivars. Oblica exhibited an ability to keep a higher K+ : Na+ ratio at all salinity levels compared to Leccino, but since no difference was found in leaf K+ concentration, this was mainly achieved by less Na+ ions reaching the younger leaves. The antioxidative system represents a component of the complex olive salt‐tolerance mechanism, and it seems that the role of SOD in protection from oxidative stress depends on sodium accumulation in leaves.
Saltbush (Atriplex lampa) leaf protein concentrate by ultrafiltration for use in balanced animal feed formulations
Authors: Fernández Silvia S. , Menéndez Carlos , Mucciarelli Sara , Padilla Antonio P. 
Published: May 2007

AbstractThe purpose of this study was to evaluate the use of ultrafiltration and discontinuous diafiltration (DD) to obtain a protein concentrate from Atriplex lampa saltbush, improving its palatability by decreasing the salt content (mainly sodium and potassium chloride). The experimental work was done using a Pellicon® cassette (25 units) system equipped with polyethersulfone organic membranes with a molecular weight cut‐off value of 10 kD. The characteristic of the membranes and the feed material, the parameters and operational conditions were studied in the pretreatment of the sample as well as in the ultrafiltration process to obtain a maximum performance. The product obtained contained 85% protein on aa dry weight basis and a marked decrease in salt content, from 40% in fresh leaves to 2.5% after processing by DD, which is in agreement with the average conductivity values observed, from 18.1 mS cm−1 in the initial aqueous alkaline extract to a final value of 3.5 mS cm−1. Measurements of normalized water permeability were determined after each wash cycle in order to verify the flow recovery through the membrane. Analysis of amino acids from the protein concentrate with a chemical score of 85.13 was calculated using a Food Agricultural Organization reference pattern (sulfur amino acids as limiting amino acids). Nitrogen retention was evaluated by means of a biological test and the following values were obtained: net protein utilization = 63.00 ± 4.00, true digestibility = 79.00 ± 5.21, and biological value = 79.80. The presence of oxalic acid, nitrates, saponins, phenolic compounds and condensate tannins is not significant. The results indicate that the concentrate obtained has a high content of lysine, making these products particularly useful as a complement for cereal flour, which is deficient in this amino acid. The determined values suggest that the product can be used in balanced animal feed formulation. Copyright © 2007 Society of Chemical Industry
Gas chromatography coupled to mass spectrometry for analyses of organic compounds and biomarkers as tracers for geological, environmental, and forensic research
Authors: Medeiros Patricia M. , Simoneit Bernd R. T. 
Published: May 2007

AbstractGas chromatography, especially when coupled with mass spectrometry, is the analytical method of choice for elucidation of biomarker compounds present in organic mixtures extracted from geological, environmental, and biological samples. This review describes the biomarker concept,i. e., the precursor natural products to the geological/environmental derivatives, and their application as multi‐tracers in the geosphere and ambient environment. The mass spectrometric methods currently utilized for such analyses are reviewed with a general key to the literature, and typical examples of applications using GC–MS are also described.
Bridged Silsesquioxanes with Organic Domains Self‐Assembled as Functionalized Molecular Channels
Authors: Romeo Hernán E. , Fanovich María A. , Williams Roberto J. J. , Matějka Libor , Pleštil Josef , Brus Jiří 
Published: May 2007

AbstractA bridged silsesquioxane was obtained from a precursor synthesized by the reaction of glycidoxypropyl(trimethoxysilane) (2 mol) with cyclohexylamine (1 mol). The polycondensation in the presence of formic acid produced a hybrid material exhibiting a short‐range order based on elongated organic channels accommodating the pendant cyclohexyl fragments, bounded by inorganic domains. The presence of functional groups in the organic channels (tertiary amine, ether, hydroxyl), can be used to retain small organic molecules capable of forming hydrogen bonds. Aspirin was used as a probe to illustrate this possibility.magnified image
THE JUDGEMENT CALCULUS FOR INTUITIONISTIC LINEAR LOGIC: PROOF THEORY AND SEMANTICS
Authors: Valentini Silvio 
Published: May 2007

AbstractIn this paper we propose a new set of rules for a judgement calculus, i.e. a typed lambda calculus, based on Intuitionistic Linear Logic; these rules ease the problem of defining a suitable mathematical semantics. A proof of the canonical form theorem for this new system is given: it assures, beside the consistency of the calculus, the termination of the evaluation process of every well‐typed element. The definition of the mathematical semantics and a completeness theorem, that turns out to be a representation theorem, follow. This semantics is the basis to obtain a semantics for the evaluation process of every well‐typed program. 1991 MSC: 03B20, 03B40.
CUT ELIMINATION FOR PROPOSITIONAL DYNAMIC LOGIC WITHOUT
Authors: Bull Robert A. 
Published: May 2007

AbstractThe aim of this paper is to extend the semantic analysis of tense logic in Rescher/Urquhart [3] to propositional dynamic logic without*. For this we develop a nested sequential calculus whose axioms and rules directly reflect the steps in the semantic analysis. It is shown that this calculus, with the cut rule omitted, is complete with respect to the standard semantics. It follows that cut elimination does hold for this nested sequential calculus. MSC: 03B45.
RECONSTRUCTION OF BINARY RELATIONS FROM THEIR RESTRICTIONS OF CARDINALITY 2, 3, 4 and (n ‐ 1) II
Authors: Lopez Gérard , Rauzy Claire 
Published: May 2007

AbstractWe shall prove here that any binary relation on a base E with cardinality n > 6 is reconstructible from its restrictions of cardinality 2, 3, 4 and (n ‐ 1). This proof needs results of part I of this paper where we characterize any pair of relations R, R' which are 2‐, 3‐ and 4‐hypomorphic. As a corollary we obtain that any binary relation is (n ‐ 4)‐reconstructible (when n > 9).
A BRIEF SURVEY OF FRAMES FOR THE LAMBEK CALCULUS
Authors: Došen Kosta 
Published: May 2007

AbstractModels for the Lambek calculus of syntactic categories surveyed here are based on frames that are in principle of the same type as Kripke frames for intuitionistic logic. These models are extracted from the literature on models for relevant logics, in particular the ternary relationed models introduced in the early seventies. The purpose of this brief survey is to locate some open completeness problems for variants of the Lambek calculus in the context of completeness results based on various types of ternary relational models.
BOOLEAN ALGEBRAS IN AST
Authors: Schumacher Klaus 
Published: May 2007

AbstractIn this paper we investigate Boolean algebras and their subalgebras in Alternative Set Theory (AST). We show that any two countable atomless Boolean algebras are isomorphic and we give an example of such a Boolean algebra. One other main result is, that there is an infinite Boolean algebra freely generated by a set. At the end of the paper we show that the sentence “There is no non‐trivial free group which is a set” is consistent with AST.
Forcing in Finite Structures
Authors: Zambella Domenico 
Published: May 2007

AbstractWe present a simple and completely model‐theoretical proof of a strengthening of a theorem of Ajtai: The independence of the pigeonhole principle fromIΔ0(R). With regard to strength, the theorem proved here corresponds to the complexity/proof‐theoretical results of [10] and [14], but a different combinatorics is used. Techniques inspired by Razborov [11] replace those derived from Håstad [8]. This leads to a much shorter and very direct construction.
Transformation and reduction formulae for double q‐Clausen hypergeometric series
Authors: Chu Wenchang , Jia Cangzhi 
Published: May 2007

AbstractBy means of the Sears transformations, we establish eight general transformation theorems on bivariate basic hypergeometric series. Several transformation, reduction and summation formulae on the double q‐Clausen hypergeometric series are derived as consequences. Copyright © 2007 John Wiley & Sons, Ltd.
Shock formation in a chemotaxis model
Authors: Wang Zhian , Hillen Thomas 
Published: May 2007

AbstractIn this paper, we establish the existence of shock solutions for a simplified version of the Othmer–Stevens chemotaxis model (SIAM J. Appl. Math. 1997; 57:1044–1081). The existence of these shock solutions was suggested by Levine and Sleeman (SIAM J. Appl. Math. 1997; 57:683–730). Here, we consider the general Riemann problem and derive the shock curves in parameterized forms. By studying the travelling wave solutions, we examine the shock structure for the chemotaxis model and prove that the travelling wave speed is identical to the shock speed. Moreover, we explicitly derive an entropy–entropy flux pair to prove the uniqueness of the weak shock solutions. Some discussion is given for further study. Copyright © 2007 John Wiley & Sons, Ltd.
Berry anthocyanins as novel antioxidants in human health and disease prevention
Authors: Zafra‐Stone Shirley , Yasmin Taharat , Bagchi Manashi , Chatterjee Archana , Vinson Joe A. , Bagchi Debasis 
Published: May 2007

AbstractEdible berries, a potential source of natural anthocyanin antioxidants, have demonstrated a broad spectrum of biomedical functions. These include cardiovascular disorders, advancing age‐induced oxidative stress, inflammatory responses, and diverse degenerative diseases. Berry anthocyanins also improve neuronal and cognitive brain functions, ocular health as well as protect genomic DNA integrity. This chapter demonstrates the beneficial effects of wild blueberry, bilberry, cranberry, elderberry, raspberry seeds, and strawberry in human health and disease prevention. Furthermore, this chapter will discuss the pharmacological benefits of a novel combination of selected berry extracts known as OptiBerry, a combination of wild blueberry, wild bilberry, cranberry, elderberry, raspberry seeds, and strawberry, and its potential benefit over individual berries. Recent studies in our laboratories have demonstrated that OptiBerry exhibits high antioxidant efficacy as shown by its high oxygen radical absorbance capacity (ORAC) values, novel antiangiogenic and antiatherosclerotic activities, and potential cytotoxicity towardsHelicobacter pylori, a noxious pathogen responsible for various gastrointestinal disorders including duodenal ulcer and gastric cancer, as compared to individual berry extracts. OptiBerry also significantly inhibited basal MCP‐1 and inducible NF‐κβ transcriptions as well as the inflammatory biomarker IL‐8, and significantly reduced the ability to form hemangioma and markedly decreased EOMA cell‐induced tumor growth in anin vivomodel. Overall, berry anthocyanins trigger genetic signaling in promoting human health and disease prevention.