bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthese und Eigenschaften des Benzofuryl‐(3)‐carbinols und Benzofuran‐aldehyds‐(3)
Authors: Capuano Lilly
Published: June 2007

Die Reduktion des leicht zugänglichen Benzofuran‐carbonsäure‐(3)‐methylesters (1) ergab in guter Ausbeute Benzofuryl‐(3)‐carbinol (2). Der daraus durch Oxydation gewonnene Benzofuran‐aldehyd‐(3) (3) wurde durch Diazomethan bei Gegenwart von Methanol in 3‐Acetonyl‐benzofuran (4) umgewandelt.
Präparative photochemische Synthesen, III. Eine einfache Synthese der Norcaryophyllensäuren
Authors: Scharf Hans‐Dieter , Korte Friedhelm
Published: June 2007

Dichlormaleinsäureanhydrid und das entsprechende Imid werden in einer photochemischen Basisreaktion an Isobutylen cycloaddiert. Dabei entstehen stereospezifisch die entsprechenden Derivate der cis‐1.2‐Dichlor‐norcaryophyllensäure, die durch Enthalogenierungsreaktionen in die Dehydro‐ und in die racemischen cis‐ und trans‐Norcaryophyllensäuren übergeführt werden. PMR‐Daten und pKa‐Werte dieser Substanzen werden angegeben.
Synthese und Eigenschaften eines bicyclischen Oxoniumsalzes
Authors: Klages Friedrich , Jung Herbert A. , Wagner Hans
Published: June 2007

Die Konfiguration des mesomeriefreien dreibindigen Oxonium‐O‐Atoms wurde durch Synthese des chinuclidinanalogen 1‐Oxonia‐bicyclo[2.2.2]octan‐Ringsystems im Sinne einer pyramidalen Ligandenanordnung sichergestellt (zumindest für diesen Spezialfall). Der zweite Ringschluß gelingt wegen der ungünstigen Konformationsverhältnisse nur in geringen Ausbeuten und nur bei der Umsetzung von 4‐[β‐Jod‐äthyl]‐tetrahydropyran mit Silber‐hexafluoroantimonat, während mit Silber‐tetrafluoroborat als Ausweichreaktion eine intermolekulare Alkylierung des Äthersauerstoffs zu einem Polyoxoniumsalz erfolgt.
Aciditätsbestimmung mit Hilfe aliphatischer Diazoverbindungen. II. Die Aufstellung einer dynamischen Aciditätsreihe
Authors: Klages Friedrich , Bott Kaspar , Hegenberg Peter , Jung Herbert A.
Published: June 2007

Auf Grund der schon früher zur Messung von Säurestärken verwandten Geschwindigkeit der Säurezersetzung aliphatischer Diazoverbindungen wurde ein Aciditätsbestimmungsverfahren ausgearbeitet, das bei Verwendung mehrerer Diazoverbindungen abgestufter Säureempfindlichkeit einen bereits nahezu 10 Zehnerpotenzen breiten Aciditätsbereich lückenlos erfaßt. Die als Maß der Aciditätsdifferenz zweier Säuren dienenden Quotienten der Reaktionsgeschwindigkeitskonstanten sind innerhalb der Fehlergrenzen unabhängig von den jeweils zur Messung verwandten Diazoverbindungen, so daß eine rechnerische Eliminierung des Einflusses der letzteren und damit die Aufstellung einer eindeutigen Aciditätsreihe ermöglicht wird.
Chemie der Cyansäureester, XI. Umsetzung von Cyansäureestern mit Verbindungen mit nucleophilem Kohlenstoff und 1.3‐dipolaren Agenzien
Authors: Grigat Ernst , Pütter Rolf , Mühlbauer Ernst
Published: June 2007

Cyansäureester übertragen ihre CN‐Gruppe auf Verbindungen mit nucleophilem Kohlenstoffatom. Dabei lassen sich in einigen Fällen die als Zwischenstufe zu formulierenden Imidsäureester (3) isolieren. — Cyansäureester addieren sich unter Ringschluß an Alkaliazide zu Tetrazol‐Derivaten (12), an Nitrone zu Oxadiazolinen (13). — Aus Dithiokohlensäure‐methylester‐phenylhydrazid (14) und Cyansäureestern bilden sich Triazol‐Derivate (15a).
4H‐1.4‐Benzthiazine aus Benzthiazoliumsalzen
Authors: Friedrich Walter , Kröhnke Fritz , Schiller Peter
Published: June 2007

Das Halbmercaptol 4 aus N‐Phenacyl‐benzthiazoliumbromid (1) geht unter Wasserabspaltung in 2‐Phenyl‐N‐formyl‐4H‐1.4‐benzthiazin (5) über. Der oxydative Übergang in ein Disulfid (7) sowie das Verhalten gegenüber elektrophilen Agenzien in alkalischer Lösung widersprechen dem nicht. Die Arbeit beschreibt noch einen zweiten Weg zu 1.4‐Benzthiazinen.
Lichtreaktionen mit Carbonsäurederivaten, V. Eliminierung doppelt gebundenen Schwefels durch Bestrahlung: Endioläther aus Thionestern und Isonitrile aus Senfölen. Erzeugung atomaren Schwefels in Lösung
Authors: Schmidt Ulrich , Kabitzke Karlheinz , Boie Immo , Osterroht Christoph
Published: June 2007

Aliphatische Thioncarbonsäureester spalten beim Bestrahlen mit Licht der Wellenlänge 254 mμ Schwefel ab und bilden Endioläther. Die Reaktion verläuft vermutlich über 1.2‐Dithia‐cyclobutane, die S2 abspalten. Mechanismen mit successiver Abspaltung der beiden Schwefelatome können ausgeschlossen werden, da sich die Bildung atomaren Schwefels nicht nachweisen läßt und das Äthylensulfid 6 (das Produkt der Abspaltung eines Schwefelatoms aus zwei Molekülen Thioncarbonsäureester) nicht Zwischenprodukt, sondern nur Nebenprodukt der Lichtreaktion ist. — Senföle bilden bei der Belichtung Isonitrile und atomaren Schwefel, der durch Addition an Cyclohexen zu Cyclohexensulfid nachgewiesen wird.
Vierringsynthesen durch photosensibilisierte Cycloaddition von Maleinsäureanhydrid an halogenierte Olefine
Authors: Steinmetz Reinhard , Hartmann Willy , Schenck Günther Otto
Published: June 2007

Die durch Benzophenon photosensibilisierte Cycloaddition von Maleinsäureanhydrid (1) an Chlor‐ oder Bromolefine macht halogenierte Cyclobutanderivate leicht zugänglich. Die Mischpolymerisation mit 1 wird bereits durch ein Halogenatom an der Doppelbindung inhibiert. Aus 1 in cis‐Dichloräthylen entstehen unter Erhaltung der Konfiguration die stereoisomeren cis‐Dichlorcyclobutanderivate vom syn‐Typ 14a und anti‐Typ 15a im Verhältnis 81 : 19. Die sterische Selektion dieser Cycloaddition ist stark lösungsmittelabhängig. So dirigiert Acetonitril (hohe DK) vollständig zu 14a, während Tetrachlorkohlenstoff (niedrige DK) 15a zum Hauptprodukt macht. Beim Belichten von 1 in trans‐Dichloräthylen entstehen die Cycloaddukte des cis‐Dichloräthylens, das durch sensibilisierte Photoisomerisierung aus trans‐Dichloräthylen hervorgeht. Die NMR‐Spektren einiger ausgewählter Cyclobutanderivate zeigen eine Abhängigkeit des Vorzeichens der über vier Bindungen erfolgenden Kopplung der diagonal angeordneten Protonen von ihrer räumlichen Stellung zueinander.
Über Verbindungen mit Urotropin‐Struktur, XXXIII. Über eine neue Möglichkeit des Ringschlusses zu 1.3‐disubstituierten Adamantanen
Authors: Stetter Hermann , Gärtner Jürgen , Tacke Peter
Published: June 2007

3‐Methylen‐bicyclo[3.3.1]nonanon‐(7) (1) cyclisierte unter Säurekatalyse sehr leicht zu in 3‐Stellung substituierten 1‐Hydroxy‐adamantanen. Auf diese Weise wurden 1.3‐Dihydroxy‐adamantan, 1‐Chlor‐3‐hydroxy‐adamantan und 1‐Acetamino‐3‐hydroxy‐adamantan erhalten. Die säurekatalysierte Umsetzung in Anisol ergab 1.3‐Bis‐[p‐methoxy‐phenyl]‐adamantan. Auch Ammoniak und Piperidin reagieren mit 1 glatt zu 1‐Amino‐3‐hydroxy‐adamantan und 1‐Piperidino‐3‐hydroxy‐adamantan. Durch Säurekatalyse in indifferenten Lösungsmitteln wurden Polyäther des Adamantans erhalten.
Eine neue Synthese von arylsubstituierten 3‐Aza‐pyrylium‐Salzen und ihre Umsetzung mit CH‐aciden Verbindungen
Authors: Schmidt Richard R.
Published: June 2007

Die Umsetzung der aus 4H‐1.3‐Oxazinen und Tritylperchlorat gewonnenen 3‐Aza‐pyrylium‐perchlorate mit CH‐aciden Verbindungen führt zu substituierten cis‐trans‐isomeren Butadien‐Derivaten, die thermisch und teilweise durch Einwirkung von Triäthylamin außerordentlich leicht zu Pyridin‐Derivaten cyclisieren. Die Umsetzung von 4‐Methylmercapto‐2‐aryl‐5.6‐tetramethylen‐3‐azapyrylium‐jodiden mit Malodinitril lieferte die analogen substituierten Isochinolin‐Derivate. Es liegt hier ein neuer Pyridin‐Ringschluß einer ungesättigten 5‐Kohlenstoffkette vor.
Zerfallsreaktionen des Diazoessigsäure‐allylesters
Authors: Kirmse Wolfgang , Dietrich Hilmar
Published: June 2007

Zersetzung von Diazoessigsäure‐allylester (1) mit Kupferkatalysatoren liefert das bicyclische Lacton 2 neben den „Dimeren”︁ 3 und 4. Die Addition an Cyclohexen konkurriert etwa gleichberechtigt mit der intramolekularen Addition zu 2. Photolyse von 1 führt ausschließlich zu Reaktionen mit dem Lösungsmittel (Cyclohexan, Benzol).
Magnetic resonance imaging of atherosclerosis by targeting extracellular matrix deposition with Gadofluorine M
Authors: Meding Jörg , Urich Matthias , Licha Kai , Reinhardt Michael , Misselwitz Bernd , Fayad Zahi A. , Weinmann Hanns‐Joachim
Published: June 2007

As previously reported, Gadofluorine M‐enhanced magnetic resonance imaging clearly demarcates atherosclerotic plaques from the normal vessel wall. To date, the underlying mechanism has remained unknown. Gadofluorine M is a gadolinium‐containing macrocyclic contrast agent containing hydrophilic and hydrophobic moieties. To elucidate the mechanism of accumulation, fluorescently labeled and radioactively labeled derivates of Gadofluorine M were used to determine affinity and specificity of Gadofluorine M binding to blood serum and plaque components in vitro and for the distribution within the plaque of WHHL rabbits in vivo. Gadofluorine M binds to serum albumin, leading to a breakdown of micelles after intravenous injection. The affinity of Gadofluorine M to serum albumin is kD = 2 µmol/l. Gadofluorine then penetrates the atherosclerotic plaque while bound to albumin and then accumulates within the extracellular, fibrous parts of the plaque by binding to collagens, proteoglycans and tenascin, having the same affinity to these plaque constituents as to albumin. In contrast, weak binding was determined to LDL (kD = 2 mmol/l) and even no binding to hyaluronic acid. The driving force of binding and accumulation is the hydrophobic moiety of the molecules interacting with hydrophobic plaque materials. Thus, Gadofluorine M accumulates within the fibrous plaque or in the fibrous cap of a plaque containing high amounts of extracellular matrix components, but not in the lipid‐rich areas. In combination with high‐resolution MRI, Gadofluorine M might enable the detection of thin‐cap fibroatheromas, also named the vulnerable plaque. Copyright © 2007 John Wiley & Sons, Ltd.
Fostering collaboration to better manage water resources
Authors: Voorsluys William , Araújo Eliane , Cirne Walfredo , Galvão Carlos O. , Souza Enio P. , Cavalcanti Enilson P.
Published: June 2007

Good water management is literally vital for the arid and semi‐arid regions of the planet. Yet good water management requires multidisciplinary expertise, since one must consider climatic, hydrological, economical and social aspects to make balanced decisions on water usage. We here present SegHidro, a Grid portal designed to foster scientific, technical and operational collaboration to improve water resources management. The portal targets researchers and decision makers, enabling them to execute and couple their computational models in a workflow. The portal provides a framework which allows seamless integration of the models, meaning that each phase of the flow may be executed by a different expert and that the resulting data are shared among other portal users. Due to the nature of these applications and the need to execute many prospective scenarios, their execution requires high computing power. However, we go beyond providing high‐performance computational Grid capabilities. We also enable people to complement each other's expertise in understanding the trade‐offs in the water allocation decisions. The SegHidro portal is about sharing: human expertise, data and computing power. Copyright © 2007 John Wiley & Sons, Ltd.
The Grid Resource Broker portal
Authors: Aloisio G. , Cafaro M. , Carteni G. , Epicoco I. , Fiore S. , Lezzi D. , Mirto M. , Mocavero S.
Published: June 2007

This paper describes the Grid Resource Broker (GRB), a Grid portal built leveraging a set of high‐level, Globus‐Toolkit‐based Grid libraries called GRB libraries. The portal leverages the Liferay framework to provide users with an intuitive, highly customizable Web GUI. The underlying GRB middleware allows trusted users seamless access to their computational Grid environments. Copyright © 2007 John Wiley & Sons, Ltd.
Developing portals/portlets using Enterprise JavaBeans for Grid users
Authors: Yang X. , Akram A. , Allan R. J.
Published: June 2007

A Web‐based portal acting as a presentation layer to the Grid allows us to provide a transparent means of access to Grid resources. Our previous experiences in developing Grid portals have shown that there is a need to draw a clear high‐level picture of the architecture. This could be defined using the J2EE component‐oriented architecture, which enables a clear separation between the presentation, business logic and data layers. Additional benefits come with J2EE 1.4 making it possible to build up advanced service‐based Grid portals by exposing stateless session beans as Web services. In this paper, lessons learnt from our prototype portal/portlet development using Enterprise JavaBeans (EJB) are reported. Copyright © 2007 John Wiley & Sons, Ltd.
Novel genes involved in Ciona intestinalis embryogenesis: Characterization of gene knockdown embryos
Authors: Hamada Mayuko , Wada Shuichi , Kobayashi Kenji , Satoh Nori
Published: June 2007

The sequenced genome of the urochordate ascidian Ciona intestinalis contains nearly 2,500 genes that have vertebrate homologues, but their functions are as yet unknown. To identify novel genes involved in early chordates embryogenesis, we previously screened 200 Ciona genes by knockdown experiments using specific morpholino oligonucleotides and found that suppression of the translation of 40 genes caused embryonic defects (Yamada et al. [2003] Development 130:6485–6495). We have since examined an additional 304 genes, that is, screening 504 genes overall, and a total of 111 genes showed morphological defects when gene function was suppressed. We further examined the role of these genes in the differentiation of six major tissues of the embryo: endoderm, muscle, epidermis, neural tissue, mesenchyme, and notochord. Based on the similarity of phenotypes of gene knockdown embryos, genes were categorized into several groups, with the suggestion that the genes within a given group are involved in similar developmental processes. For example, five were shown to be novel genes that are likely involved in β‐catenin–mediated endoderm formation. The type of large‐scale screening used is, therefore, a powerful approach to identify novel genes with significant developmental functions, the details of which will be determined in future studies. Developmental Dynamics 236:1820–1831, 2007. © 2007 Wiley‐Liss, Inc.
Disruption of fibroblast growth factor receptor 3 signaling results in defects in cellular differentiation, neuronal patterning, and hearing impairment
Authors: Puligilla Chandrakala , Feng Feng , Ishikawa Kotaro , Bertuzzi Stefano , Dabdoub Alain , Griffith Andrew J. , Fritzsch Bernd , Kelley Matthew W.
Published: June 2007

Deletion of fibroblast growth factor receptor 3 (Fgfr3) leads to hearing impairment in mice due to defects in the development of the organ of Corti, the sensory epithelium of the Cochlea. To examine the role of FGFR3 in auditory development, cochleae from Fgfr3−/− mice were examined using anatomical and physiological methods. Deletion of Fgfr3 leads to the absence of inner pillar cells and an increase in other cell types, suggesting that FGFR3 regulates cell fate. Defects in outer hair cell differentiation were also observed and probably represent the primary basis for hearing loss. Furthermore, innervation defects were detected consistent with changes in the fiber guidance properties of pillar cells. To elucidate the mechanisms underlying the effects of FGFR3, we examined the expression of Bmp4, a known target. Bmp4 was increased in Fgfr3−/− cochleae, and exogenous application of bone morphogenetic protein 4 (BMP4) onto cochlear explants induced a significant increase in the outer hair cells, suggesting the Fgf and Bmp signaling act in concert to pattern the cochlea. Developmental Dynamics 236:1905–1917, 2007. Published 2007 Wiley‐Liss, Inc.
Statistical inference for atmospheric transport models using process convolutions
Authors: Zhou Weining , Sansó Bruno
Published: June 2007

A computer simulator for atmospheric concentrations of chemical species, or chemical transport model, is used to simulate global ozone concentrations. Two different wind forcings are considered: one is a combination of a numerical weather prediction model and observational data, the other is obtained as output from a climate model. The goal is to study the impact of meteorological variability on ozone. The statistical approach that we consider consists on learning the spatial structure of ozone concentrations by using process convolutions. We use several Bayesian model comparison methods to determine if the two simulations can be considered as realizations of the same random field. The methods provide a quantification of the differences for each of the computer model grid cells. Copyright © 2007 John Wiley & Sons, Ltd.
Implications of neuropsychological test results of women in a new phase of anorexia nervosa
Authors: Thompson Simon B. N.
Published: June 2007

A study involving 10 female anorectics who satisfied DSM‐III‐R (American Psychiatric Association, 1987) criteria in a new phase of outpatient treatment and 10 healthy female controls matched for age, education, social class, premorbid IQ and geographical habitation, were administered a battery of well‐known neuropsychological tests and rating scales. Personal details concerning subjects' weight history and parents' occupations were also recorded.

Significant evidence was found to suggest a difference between the anorectics and the controls on a number of tests and scales. In particular, anorectics performed worse on the third trial of the Auditory Verbal Learning Test and on the Rey‐Osterreith Complex Figure Test (Delayed Recall Trial) possibly implying impairment of the right hemisphere considered to be responsible, in part, for visuospatial ability. This was believed to be one of the reasons for distortion of body image in anorexia nervosa.

Strong evidence was also found in support of the coexistence of obsessionality and depression in anorexia nervosa. Since there is growing evidence implicating the caudate nucleus for the obsessionality in obsessive‐compulsive disorder, it was proposed that this association might also be likely to explain the obsessionality in anorexia nervosa, thus supporting hypotheses that propose an organic origin for the condition.
Inpatient treatment for anorexia nervosa: A lenient approach
Authors: Grave Ricardo Dalle , Bartocci Claudia , Todisco Patrizia , Pantano Michela , Bosello Ottavio
Published: June 2007

This paper describes a lenient treatment for anorexia nervosa patients. The method incorporates nutritional rehabilitation, psychoeducational groups, parental psychoeducational groups, physiotherapy and individual psychotherapy (psychodynamically oriented). The model entails a multi‐level matching system where patients' needs are coordinated with the appropriate treatment setting. The three‐level system integrates: a hospital eating disorder unit; day care treatment as transition phase from inpatient to outpatient, and outpatient treatment. Patients shift between levels according to their progress. The therapeutic elements of the programme are presented in detail with results obtained from 44 patients.
Anaerobic exercise as an adjunct to refeeding patients with anorexia nervosa: Does it compromise weight gain?
Authors: Touyz Stephen W. , Lennerts Wolfgang , Arthur Brenden , Beumont Peter J. V.
Published: June 2007

The present study compared the rate of weight gain during refeeding in 39 patients with anorexia nervosa. Patients were allocated to two cohorts with one receiving a structured anaerobic exercise programme and the other not. A retrospective analysis of their records revealed that there was no significant difference in the rate of weight gain between the two groups. The clinical implications of this finding are encouraging as it suggests that the inclusion of a formalized exercise programme during refeeding may not necessarily adversely affect weight gain and may improve compliance. Exercise counselling in anorexia nervosa is an important but often neglected component of treatment.
Cytotoxicity evaluation of an antibacterial dentin adhesive system on established cell lines
Authors: Koulaouzidou Elizabeth A. , Helvatjoglu‐Antoniades Maria , Palaghias George , Karanika‐Kouma Artemis , Antoniades Dimitrios
Published: June 2007

Clearfil Protect Bond is a new dental bonding agent recently introduced into clinical practice. It contains an antibacterial monomer that contributes to its antibacterial profile. The aim of the present study was to evaluate cytotoxic effect of Clearfil Protect Bond against three established fibroblastic cell lines, in comparison with four commonly used adhesive materials (Adper Scotchbond 1, Excite, Tyrian SPE, and One Step plus). The experiments were performed using RPC‐C2A, BHK21/C13, and MRC5 cell lines. Test specimens, either cured or uncured, were placed in a culture medium and the extraction media were used as experimental material. The effect of the bonding materials was assessed by a modified sulforhodamine‐B assay after 24 and 48 h of exposure. All tested agents exhibited an antiproliferative effect on cells, the effect on RPC‐C2A being the most marked. Extraction media from the uncured materials were without exception highly cytotoxic. In the experiments performed using extraction medium from cured material, Clearfil Protect Bond appeared to be the least toxic material, followed by Tyrian SPE and One Step plus. Adper Scotchbond 1 and Excite exhibited the strongest cytotoxic effect. The cell survival percentage ranged between 66 and 97% for Clearfil Protect bond, 15 and 82% for Tyrian SPE, 28 and 58% for One Step plus, 2 and 28% for Excite, and 1 and 6% for Adper Scotchbond 1. Taking into consideration the limitations of anin vitrostudy, our results indicate that the new antibacterial dental adhesive system is suitable for clinical application. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Orientation embedding of signed graphs
Authors: Zaslavsky Thomas
Published: June 2007

A signed graph Σ consists of a graph and a sign labeling of its edges. A polygon in Σ is “balanced” if its sign product is positiive. A signed graph is “orientatio embedded” in a surface if it is topologically embedded and a polygon is balanced precisely when traveling once around it preserves orientation. We explore the extension to orientation embedding of the ordinary theory of graph embedding. Let d(Σ) be the demigenus (= 2 ‐ x(S)) of the unique smallest surface S in which Σ has an orientation embedding. Our main results are an easy one, that if Σ has connected components Σ1, Σ[2], ⃛, then d(Σ) = d(Σ1) + ⃛, and a hard one, that if Σ has a cut vertex v that splits Σ into Σ1, Σ2, ⃛, then d(Σ) = d(Σ1) + d(Σ2) + ⃛ ‐δ, where δ depends on the number of Σi in which v is “loopable”, that is, in which d(Σi) = d(Σi with a negative loop added to v). This is as with ordinary orientable grpah embedidng except for the existence of the term δ in the cut‐vertex formula. Since loopability is crucial, we give some partial criteria for it. (A complete characterization seems difficult.) We conclude with an application to forbidden subgraphs and minors for orientation embeddability in a given surface. © 1929 John Wiley & Sons, Inc.
Chromatic polynomials, polygon trees, and outerplanar graphs
Authors: Wakelin C. D. , Woodall D. R.
Published: June 2007

It is proved that all classes of polygon trees are characterized by their chromatic polynomials, and a characterization is given of those polynominals that are chromatic polynomials of outerplanar graphs. The first result yields an alternative proof that outerplanar graphs are recognizable from their vertex‐deleted subgraphs. © 1929 John Wiley & Sons, Inc.
Subgraphs and well‐quasi‐ordering
Authors: Ding Guoli
Published: June 2007

Let 𝒴 be a class of graphs and let ⪯ be the subgraph or the induced subgraph relation. We call ⪯ an ideal (with respect to ⪯) if ⪯ implies that ⪯. In this paper, we study the ideals that are well‐quasiordered by ⪯. The following are our main results. If ⪯ is the subgraph relation, we characterize the well‐quasi‐ordered ideals in terms of exluding subgraphs. If⪯is the induced subgraph relation, we present three wellquasi‐ordered ideals. We also construct examples to disprove some of the possible generalizations of our results. The connections between some of our results and digraphs are considered in this paper too.
Nearly uniform distribution of edges among k‐subgraphs of a graph
Authors: Širáň Jozef , Tuza Zsolt
Published: June 2007

We investigate the behavior of the function f = f(n, k, e) defined as the smallest integer with the following property: If in a graph on n vertices, the numbers of edges in any two induced subgraphs on k vertices differ by at most e, then the graph or its complement has at most f edges. One of the results states that

. © 1929 John Wiley & Sons, Inc.
Cubic graphs with 62 vertices 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. The entry (i,j) in this matrix is the number of simple paths in G having initial vertex v and length j. It was known that there are cubic graphs on 90 vertices having the same path layer matrix (Dobrynin, 1990). A new upper bound for the least order of cubic graphs with the same path layer matrix is presented. © 1993 John Wiley & Sons, Inc.
Edge‐chromatic critical graphs and the existence of 1‐factors
Authors: Choudum S. A.
Published: June 2007

We give examples of edge‐chromatic critical graphs G of the following types: (i) of even order and having no 1‐factor, and (ii) of odd order and having a vertex v of minimum degree such that G − v has no 1‐factor. The first disproves a conjecture of S. Fiorini and R. J. Wilson, and the second answers a question of A. G. Chetwynd and H. P. Yap in the negative. © 1993 John Wiley & Sons, Inc.
A note on the characterization of domination perfect graphs
Authors: Fulman Jason
Published: June 2007

A graph G is domination perfect if for each induced subgraph H of G, γ(H) = i(H), where γ and i are a graph's domination number and independent domination number, respectively. Zverovich and Zverovich [3] offered a finite forbidden induced characterization of domination perfect graphs. This characterization is not correct, but the ideas in [3] can be used to weaken the known sufficient conditions for a graph to be domination perfect and to obtain short proofs of some results regarding domination perfect graphs. © 1993 John Wiley & Sons, Inc.
Large P4‐free graphs with bounded degree
Authors: Chung Myung S. , West Douglas B.
Published: June 2007

Let ex * (D; H) denote the maximum number of edges in a connected graph with maximum degree D and no induced subgraph isomorphic to H. We prove that this is finite only when H is a disjoint union of paths,m in which case we provide crude upper and lower bounds. When H is the four‐vertex path P4, we prove that the complete bipartite graph KD,D is the unique extremal graph. Furthermore, if G is a connected P4‐free graph with maximum degree D and clique number ω, then G has at most D2 − D(ω − 2)/2 edges. © 1993 John Wiley & Sons, Inc.
Extremal interval graphs
Authors: Eckhoff Jürgen
Published: June 2007

An interval graph is said to be extremal if it achieves, among all interval graphs having the same number of vertices and the same clique number, the maximum possible number of edges. We give an intrinsic characterization of extremal interval graphs and derive recurrence relations for the numbers of such graphs. © 1993 John Wiley & Sons, Inc.
On the connectivity of graphs generated by a sum of random mappings
Authors: Jaworski Jerzy , Karoński Michał
Published: June 2007

We consider four models of random directed multigraphs with n labeled vertices of out‐degree d. First we establish formal relationships between our models with respect to exact and asymptotic (as n → ∞) probabilities of possessing a graph monotone property. We also study the asymptotic behavior of the strength of connectivity of the underlying simple graphs when d = o(n). © 1993 John Wiley & Sons, Inc.
Note on hypergraphs and sphere orders
Authors: Schrijver Alexander
Published: June 2007

We show that each partial order ≤ of height 2 can be represented by spheres in Euclidean space, where inclusion represents ≤. If each element has at most k elements under it, we can do this in 2k − 1‐dimensional space. This extends a result (and a method) of Scheinerman for the case k = 2. © 1993 John Wiley & Sons, Inc.
Supereulerian complementary graphs
Authors: Lai Hong‐Jian
Published: June 2007

Nebeský in [12] show that for any simple graph with n ≥ 5 vertices, either G or Gc contains an eulerian subgraph with order at least n ‐ 1, with an explicitly described class of exceptional graphs. In this note, we show that if G is a simple graph with n ≥ 61 vertices, then either G or Gc is supereulerian, with some exceptions. We also characterize all these exceptional cases. These results are applied to show that if G is a simple graph with n ≥ 61 vertices such that both G and Gc are connected, then either G or Gc has a 4‐flow, or both G and Gc have cut‐edges. © 1993 John Wiley & Sons, Inc.
Generalized Rotation numbers
Authors: Chapman Robin J. , Haviland Julie
Published: June 2007

A rooted graph is a pair (G,x), where G is a simple undirected graph and x ∈ V(G). If G is rooted at x, its kth rotation number hk (G,x) is the minimum number of edges in a graph F of order |G| + k such that for every v ∈ V(F) we can find a copy of G in F with the root vertex x at v. When k = 0, this definition reduces to that of the rotation number h(G,x), which was introduced in [“On Rotation Numbers for Complete Bipartite Graphs,” University of Victoria, Department of Mathematics Report No. DM‐186‐IR (1979)] by E.J. Cockayne and P.J. Lorimer and subsequently calculated for complete multipartite graphs. In this paper, we estimate the kth rotation number for complete bipartite graphs G with root x in the larger vertex class, thereby generalizing results of B. Bollobás and E.J. Cockayne [“More Rotation Numbers for Complete Bipartite Graphs,” Journal of Graph Theory, Vol. 6 (1982), pp. 403–411], J. Haviland [“Cliques and Independent Sets,” Ph. D. thesis, University of Cambridge (1989)], and J. Haviland and A. Thomason [“Rotation Numbers for Complete Bipartite Graphs,” Journal of Graph Theory, Vol. 16 (1992), pp. 61–71]. © 1993 John Wiley & Sons, Inc.
A new domination conception
Authors: Stracke Christoph , Volkmann Lutz
Published: June 2007

Let f be an integer valued function defined on the vertex set V(G) of a simple graph G. We call a subset Df of V(G) a f‐dominating set of G if |N(x, G) ∩ Df| ≥ f(x) for all x ∈ V(G) — Df, where N(x, G) is the set of neighbors of x. Df is a minimum f‐dominating set if G has no f‐dominating set D′f with |Df| < |Df|. If j, k ∈ N0 = {0,1,2,…} with j ≤ k, then we define the integer valued function fj,k on V(G) by
equation image
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By μj,k(G) we denote the cardinality of a minimum fj,k‐dominating set of G.

A set D ⊆ V(G) is j‐dominating if every vertex, which is not in D, is adjacent to at least j vertices of D. The j‐domination number γj(G) is the minimum order of a j‐dominating set in G.

In this paper we shall give estimations of the new domination number μj,k(G), and with the help of these estimations we prove some new and some known upper bounds for the j‐domination number. © 1993 John Wiley & Sons, Inc.
The complete closure of a graph
Authors: Faudree Ralph , Favaron Odile , Flandrin Evelyne , Li Hao
Published: June 2007

We define the complete closure number cc(G) of a graph G of order n as the greatest integer k ≤ 2n − 3 such that the kth Bondy‐Chvátal closure Clk(G) is complete, and give some necessary or sufficient conditions for a graph to have cc(G) = k. Similarly, the complete stability cs(P) of a property P defined on all the graphs of order n is the smallest integer k such that if Clk(G) is complete then G satisfies P. For some properties P, we compare cs(P) with the classical stability s(P) of P and show that cs(P) may be far smaller than s(P). © 1993 John Wiley & Sons, Inc.
Directed distance in digraphs: Centers and medians
Authors: Chartrand Gary , Johns Garry L. , Tian Songlin , Winters Steven J.
Published: June 2007

The directed distance dD(u, v) from a vertex u to a vertex v in a strong digraph D is the length of a shortest (directed) u ‐ v path in D. The eccentricity of a vertex v in D is the directed distance from v to a vertex furthest from v. The distance of a vertex v in D is the sum of the directed distances from v to the vertices of D. The center C(D) of D is the subdigraph induced by those vertices of minimum eccentricity, while the median M(D) of D is the subdigraph induced by those vertices of minimum distance. It is shown that for every two asymmetric digraphs D1 and D2, there exists a strong asymmetric digraph H such that C(H) ≅ D1 and M(H) ≅ D2, and where the directed distance from C(H) to M(H) and from M(H) to C(H) can be arbitrarily prescribed. Furthermore, if K is a nonempty asymmetric digraph isomorphic to an induced subdigraph of both D1 and D2, then there exists a strong asymmetric digraph F such that C(F) ≅ D1, M(F) ≅ D2 and C(F) ∩ M(F) ≅ K. © 1993 John Wiley & Sons, Inc.
On minors of graphs with at least 3n −4 edges
Authors: Khalifat M. , Politof Themistocles , Satyanarayana A.
Published: June 2007

A point disconnecting set S of a graph G is a nontrivial m‐separator, where m = |S|, if the connected components of G ‐ S can be partitioned into two subgraphs, each of which has at least two points. A 3‐connected graph is quasi 4‐connected if it has no nontrivial 3‐separators. Suppose G is a graph having n ≥ 6 points. We prove three results: (1) If G is quasi 4‐connected with at least 3n ‐ 4 edges, then the graph K−1, obtained from K6 by deleting an edge, is a minor of G. (2) If G has at least 3n ‐ 4 edges then either K−6 or the graph obtained by pasting two disjoint copies of K5 together along a triangle is a minor of G. (3) If the minimum degree of G is at least 6, then K−6 is a minor of G. © 1993 John Wiley & Sons, Inc.
Equitable labelings of cycles
Authors: Wojciechowski Jerzy
Published: June 2007

Every labeling of the vertices of a graph with distinct natural numbers induces a natural labeling of its edges: the label of an edge (x, y) is the absolute value of the difference of the labels of x and y. By analogy with graceful labelings, we say that a labeling of the vertices of a graph of order n is minimally k‐equitable if the vertices are labeled with 1,2,…, n and in the induced labeling of its edges every label either occurs exactly k times or does not occur at all. Bloom [3] posed the following question: Is the condition that k is a proper divisor of n sufficient for the cycle Cn to have a minimal k‐equitable labeling? We give a positive answer to this question. © 1993 John Wiley & Sons, Inc.
A note on the last new vertex visited by a random walk
Authors: Lovász Lászlo , Winkler Peter
Published: June 2007

A “cover tour” of a connected graph G from a vertex x is a random walk that begins at x, moves at each step with equal probability to any neighbor of its current vertex, and ends when it has hit every vertex of G. The cycle Cn is well known to have the curious property that a cover tour from any vertex is equally likely to end at any other vertex; the complete graph Kn shares this property, trivially, by symmetry. Ronald L. Graham has asked whether there are any other graphs with this property; we show that there are not. © 1993 John Wiley & Sons, Inc.
Applications of balance equations to vertex switching reconstruction
Authors: Krasikov I.
Published: June 2007

A graph is called s‐vertex switching reconstructible (s‐VSR) if it is uniquely defined, up to isomorphism, by the multiset of unlabeled graphs obtained by switching of all its s‐vertex subsets. We show that a graph with n vertices is n/2‐VSR if n = 0(mod 4), (n − 2)/2‐VSR and n/2‐VSR if n = 2(mod 4), (n − 1)/2‐VSR if n = 1 (mod 2). For hypothetical nonreconstructible graphs, we give bounds on the number of edges (for any s) and on the maximum and minimum degree (for s = 2). We also show that for n > 9 the degree sequence is 2‐VSR.
Edge‐maximal (k, i)‐graphs
Authors: Lai Hong‐Jian , Zhang Cun‐Quan
Published: June 2007

A graph G is a (k, l)‐graph if for any subgraph H of G, that |V(H)| ≧ implies that k(H) ≦ k − 1. An edge‐maximal (k, l‐graph G is one such that for any e ϵ E(Gc), G + e is not a (k, l)‐graph. In [F. T. Boesch and J. A. M. McHugh, „An Edge Extremal Result for Subcohesion,”︁ Journal of Combinatorial Theory B, vol. 38 (1985), pp. 1–7] a class of edge‐maximal graphs was found and used to show best possible upper bounds of the size of edge‐maximal (k, l)‐graphs. In this paper, we investigate the lower bounds of the size of edge‐maximal (k, l)‐graphs. Let f(n, k, l) denote the minimum size of edge‐maximal (k, l)‐graphs of order n. We shall give a characterization of edge‐maximal (k, l)‐graphs. This characterization is used to determine f(n, k, l) and to characterize the edge‐maximal (k, l)‐graphs with minimum sizes, for all n ≦ k + 2 ≦ 5. Thus prior results in [F.T. Boesch and J. A. M. McHugh, op. cit.; H.‐J. Lai, „The Size of Strength‐Maximal Graphs,”︁ Journal of Graph Theory, vol. 14 (1990), pp. 187–197] are extended.
New upper bounds on harmonious colorings
Authors: Edwards Keith , McDiarmid Colin
Published: June 2007

We present an improved upper bound on the harmonious chromatic number of an arbitrary graph. We also consider „fragmentable”︁ classes of graphs (an example is the class of planar graphs) that are, roughly speaking, graphs that can be decomposed into bounded‐sized components by removing a small proportion of the vertices. We show that for such graphs of bounded degree the harmonious chromatic number is close to the lower bound (2m)1/2, where m is the number of edges.
Equistable graphs
Authors: Mahadev N. V. R. , Peled Uri N. , Sun Feng
Published: June 2007

An equistable graph is a graph for which the incidence vectors of the maximal stable sets are the 0–1 solutions of a linear equation. A necessary condition and a sufficient condition for equistability are given. They are used to characterize the equistability of various classes of perfect graphs, outerplanar graphs, and pseudothreshold graphs. Some classes of equistable graphs are shown to be closed under graph substitution.
A common generalization of line graphs and clique graphs
Authors: Prisner Erich
Published: June 2007

Both the line graph and the clique graph are defined as intersection graphs of certain families of complete subgraphs of a graph. We generalize this concept. By a k‐edge of a graph we mean a complete subgraph with k vertices or a clique with fewer than k vertices. The k‐edge graph Δk(G) of a graph G is defined as the intersection graph of the set of all k‐edges of G. The following three problems are investigated for k‐edge graphs. The first is the characterization problem. Second, sets of graphs closed under the k‐edge graph operator are found. The third problem is the question of convergence: What happens to a graph if we take iterated k‐edge graphs?
Subdivided graphs have linear ramsey numbers
Authors: Alon Noga
Published: June 2007

It is shown that the Ramsey number of any graph with n vertices in which no two vertices of degree at least 3 are adjacent is at most 12n. In particular, the above estimate holds for the Ramsey number of any n‐vertex subdivision of an arbitrary graph, provided each edge of the original graph is subdivided at least once. This settles a problem of Burr and Erdös.
Sparse color‐critical graphs and hypergraphs with no short cycles
Authors: Abbott H. L. , Zhou B. , Hare D. R.
Published: June 2007

We give constructions of color‐critical graphs and hypergraphs with no short cycles and with relatively few edges. In particular, we show that, for each n ≧ 3, the smallest number of edges in a 3‐critical triangle‐free n‐graph (hypergraph) with m vertices is m + o(m) as m → ∞. Also, for each r ≧ 4, there exists an r‐critical triangle‐free 2‐graph (graph) with m vertices and at most (r − (7/3))m + o(m) edges. Weaker results are obtained for the existence of r‐critical graphs containing no cycle of length at most / > 3.
Local edge colorings that are global
Authors: Clapsadle R. A. , Schelp R. H.
Published: June 2007

A local (H, k)‐coloring of Kn is a coloring of its edges in which each of its subgraphs isomorphic to H is colored by at most k colors. A necessary condition on H (conjectured to be sufficient) is found such that each local (H, k)‐coloring is a k‐coloring. Furthermore, necessary and sufficient conditions are given for each local (H, k)‐coloring to be a coloring by a bounded number of colors.
The greedy clique decomposition of a graph
Authors: McGuinness Sean
Published: June 2007

We prove that if maximal cliques are removed one by one from any graph with n vertices, then the graph will be empty after at most n2/4 steps. This proves a conjecture of Winkler.
Set domination in graphs
Authors: Sampathkumar E. , Latha L. Pushpa
Published: June 2007

Let G = (V, E) be a connected graph. A set D ⊂ V is a set‐dominating set (sd‐set) if for every set T ⊂ V − D, there exists a nonempty set S ⊂ D such that the subgraph 〈S ∪ T〉 induced by S ∪ T is connected. The set‐domination number γs(G) of G is the minimum cardinality of a sd‐set. In this paper we develop properties of this new parameter and relate it to some other known domination parameters.
Infinite digraphs with nonreconstructible outvalency sequences
Authors: Nash‐Williams C. S. T. J. A.
Published: June 2007

We show that the outvalency sequence of an infinite digraph is not, in general, reconstructible.
Local and global average degree in graphs and multigraphs
Authors: Bertram E. , Erds P. , Horák P. , Širáň J. , Tuza Z. S.
Published: June 2007

A vertex v of a graph G is called groupie if the average degree tv of all neighbors of v in G is not smaller than the average degree tG of G. Every graph contains a groupie vertex; the problem of whether or not every simple graph on ≧2 vertices has at least two groupie vertices turned out to be surprisingly difficult. We present various sufficient conditions for a simple graph to contain at least two groupie vertices. Further, we investigate the function f(n) = max minv (tv/tG), where the maximum ranges over all simple graphs on n vertices, and prove that f(n) = 1/42n + o(1). The corresponding result for multigraphs is in sharp contrast with the above. We also characterize trees in which the local average degree tv is constant.
Neighborhood unions and the cycle cover number of a graph
Authors: Chen Guantao , Gould Ronald J. , Jacobson Michael S. , Schelp Richard H.
Published: June 2007

For several years, the study of neighborhood unions of graphs has given rise to important structural consequences of graphs. In particular, neighborhood conditions that give rise to hamiltonian cycles have been considered in depth. In this paper we generalize these approaches to give a bound on the smallest number of cycles in G containing all the vertices of G.

We show that if for all x, y ≅ V(G), |N(x) ∩ N(y)| ≧ 2n/5 + 1, then V(G) is coverable by at most two cycles. Several related results and extensions to t cycles are also given.
On the orientation of meyniel graphs
Authors: Blidia Mostaffa , Duchet Pierre , Maffray Frédéric
Published: June 2007

A kernel of a directed graph is a set of vertices K that is both absorbant and independent (i.e., every vertex not in K is the origin of an arc whose extremity is in K, and no arc of the graph has both endpoints in K). In 1983, Meyniel conjectured that any perfect graph, directed in such a way that every circuit of length three uses two reversible arcs, must have a kernel. This conjecture was proved for parity graphs. In this paper, we extend that result and prove that Meyniel's conjecture holds for all graphs in which every odd cycle has two chords.
Nonseparable graphs with a given number of cycles
Authors: Šćepanović Ranko , Ringel Gerhard , Marušič Dragan , Chia G. L. , Alspach Brian
Published: June 2007

G. Ringel conjectured that for every positive integer n other than 2, 4, 5, 8, 9, and 16, there exists a nonseparable graph with n cycles. It is proved here that the conjecture is true even with the restriction to planar and hamiltonian graphs.
Neighborhood unions and regular factors
Authors: Niessen Thomas
Published: June 2007

We examine bounds on the size of the neighborhood union for two (independent) vertices of a graph that imply the existence of regular factors. © 1995 John Wiley & Sons, Inc.
The 7/5‐conjecture strengthens itself
Authors: Kostochka A. V.
Published: June 2007

The following is proved: if every bridgeless graph G has a cycle cover of length at most 7/5|E(G)|, then every bridgeless graph G has a cycle cover of length at most 7/5|E(G)| such that any edge of G is covered once or twice. © 1995 John Wiley & Sons, Inc.
A class of planar well‐covered graphs with girth four
Authors: Pinter Michael R.
Published: June 2007

A well‐covered graph is a graph in which every maximal independent set is a maximum independent set; Plummer introduced the concept in a 1970 paper. The notion of a 1‐well‐covered graph was introduced by Staples in her 1975 dissertation: a well‐covered graph G is 1‐well‐covered if and only if G ‐ v is also well covered for every point v in G. Except for K2 and C5, every 1‐well‐covered graph contains triangles or 4‐cycles. We show that all planar 1‐well‐covered graphs of girth 4 belong to a specific infinite family, and we give a characterization of this family. © 1995 John Wiley & Sons, Inc.
Total dominating functions in trees: Minimality and convexity
Authors: Cockayne E. J. , Mynhardt C. M. , Yu Bo
Published: June 2007

A total dominating function (TDF) of a graph G = (V, E) is a function f: V ← [0, 1] such that for each v ϵ V, ΣuϵN(v) f(u) ≥ 1 (where N(v) denotes the set of neighbors of vertex v). Convex combinations of TDFs are also TDFs. However, convex combinations of minimal TDFs (i.e., MTDFs) are not necessarily minimal.

In this paper we discuss the existence in trees of a universal MTDF (i.e., an MTDF whose convex combinations with any other MTDF are also minimal). © 1995 John Wiley & Sons, Inc.
Small graphs with chromatic number 5: A computer search
Authors: Jensen Tommy , Royle Gordon F.
Published: June 2007

In this article we give examples of a triangle‐free graph on 22 vertices with chromatic number 5 and a K4‐free graph on 11 vertices with chromatic number 5. We very briefly describe the computer searches demonstrating that these are the smallest possible such graphs. All 5‐critical graphs on 9 vertices are exhibited. © 1995 John Wiley & Sons, Inc.
Some results on the reconstruction problems. p‐claw‐free, chordal, and p4‐reducible graphs
Authors: Thatte Bhalchandra D.
Published: June 2007

A claw is an induced subgraph isomorphic to K1,3. The claw‐point is the point of degree 3 in a claw. A graph is called p‐claw‐free when no p‐cycle has a claw‐point on it. It is proved that for p ≥ 4, p‐claw‐free graphs containting at least one chordless p‐cycle are edge reconstructible. It is also proved that chordal graphs are edge reconstructible. These two results together imply the edge reconstructibility of claw‐free graphs. A simple proof of vertex reconstructibility of P4‐reducible graphs is also presented. © 1995 John Wiley & Sons, Inc.
On the average genus of the random graph
Authors: Stahl Saul
Published: June 2007

We obtain an upper bound on the expected number of regions in the randomly chosen orientable embedding of a fixed graph. This bound is ised to show that the average genus of the random graph on v vertices is close to its maximum genus. More specifically, it is proven that the difference between these two parameters is bounded by a function that is linear in v. These bounds are obtained in the context of permutation—partition pairs. © 1996 John Wiley & Sons, Inc.