Disjoint hamiltonian cycles in bipartite graphs

Let G=(X,Y) be a bipartite graph and define . Moon and Moser [J. Moon, L. Moser, On Hamiltonian bipartite graphs, Israel J. Math. 1 (1963) 163-165. MR 28 # 4540] showed that if G is a bipartite graph on 2n vertices such that , then G is hamiltonian, sharpening a classical result of Ore [O. Ore, A note on Hamilton circuits, Amer. Math. Monthly 67 (1960) 55] for bipartite graphs. Here we prove that if G is a bipartite graph on 2n vertices such that , then G contains k edge-disjoint hamiltonian cycles. This extends the result of Moon and Moser and a result of R. Faudree et al. [R. Faudree, C. Rousseau, R. Schelp, Edge-disjoint Hamiltonian cycles, Graph Theory Appl. Algorithms Comput. Sci. (1984) 231-249].     

Identification of speaker sex from one vowel across a range of fundamental frequencies

To identify a speaker's sex, listeners may rely on sex-based differences in average fundamental frequency (F0), but overlap in male and female F0 ranges undermines such judgments. To test accuracy of sex-identification throughout the F0 range, listeners were asked to judge sex based on audio recordings of /ɑ/ spoken on a number of overlapping steady F0s by 10 male and 10 female English speakers. In general, listeners performed above chance (71.6% correct). However, near range extrema, listeners followed an apparent bias toward hearing high F0s as female and low as male; confidence was high when accuracy was high and vice-versa. At mid-range, listeners identified sex fairly accurately but were not very confident in their judgments. In a forced-choice task, vowels close in F0 (but beyond the difference limen) were presented in male-female or female-male pairs. Listeners weakly identified speaker sex (63.3% correct). Identification of the male voice was considerably above chance only when the male had the lower F0 of the pair. Reliance on stereotypes of speaking F0 may bias listeners to hear low F0s as male and high F0s as female, perhaps with a contribution from vocal-tract length information. No strong evidence for a contribution of voice quality obtained.     

Covariates of corticotropin-releasing hormone (CRH) concentrations in cerebrospinal fluid (CSF) from healthy humans

Background  

Define covariates of cerebrospinal corticotropin-releasing hormone (CRH) levels in normal humans. CRH_CSF was measured in 9 normal subjects as part of an intensive study of physiological responses stressors in chronic pain and fatigue states. CRH_CSF was first correlated with demographic, vital sign, HPA axis, validated questionnaire domains, baseline and maximal responses to pain, exercise and other stressors. Significant factors were used for linear regression modeling.     

Structure–Activity relationships of effect of aryltin compounds on Ceratocystis ulmi

The effect of aryltin compounds (Ar₄Sn and Ar₃SnCl) on the growth of Ceratocystis ulmi, the causative agent of Dutch elm disease, was studied in shake culture. In all cases, the triaryltins were more effective than the tetra-aryltins as inhibitors of C. ulmi in vitro. Furthermore, substitution on the phenyl ring at the meta- and para- positions in the triaryltins did not have a major effect on the biocidal activity for the substituted triaryltins. Quantitative structure–activity relationships (QSARs) gave support to the idea that the species responsible for the inhibition of the fungus is the triaryltin cation. The QSARs further suggest that the interaction of the triaryltin cation with the fungal cell wall of C. ulmi is by a non-specific mechanism.     

Synthese von Hexadecanolid

Ohne Zusammenfassung     

The asymptotic distribution of magnitude trimmed sums for distributions in the Feller class

LetX, X ₁,X ₂,... be i.i.d. with common distribution functionF. Rather than study limit behavior of the sum,S _n =X ₁++X _n , under constant normalizations, we consider the sum with ther _n summands largest in magnitude removed from the sumS _n , wherer _n andr _n n ^–10. This is known as an intermediate magnitude trimmed sum. LetF be such that lim inf_t lim inf _t EX ² I(|X|t/)t ² P((|X|>t)>0. The collection of suchF is known as the Feller class, a large class of distributions which includes all domains of attraction (in particular the stable laws). Pruitt(¹³) showed that asymptotic normality always holds for the trimmed sums ifF is in the Feller class and ifF is symmetric. Here, for anyF in the Feller class, we obtain complete results including the form of the possible limit laws and their convergence criteria, thus generalizing Pruitt's result to the asymmetric setting.This paper forms a portion of the author's Ph.D. dissertation under the supervision of Daniel C. Weiner.     

Ring pucker in dihydroaromatic epoxides: The molecular structure ofr-1-hydroxy-t-2-methyl-t,t-3,4-epoxy-1,2,3,4-tetrahydronaphthalene

The crystal structure of the derivative of tetrahydronaphthalene with substituent epoxy, hydroxyl, and methyl groups in the more saturated ring (r-1-hydroxy-t-2-methyl-t,t-3,4-epoxy-1,2,3,4-tetrahydronaphthalene) has been determined. The hydroxyl and methyl groups are both found to beequatorial. The crystal structure is characterized by chains of molecules linked by O-H O hydrogen bonds involving the hydroxyl groups; these hydrogen bonds lie approximately parallel to theb axis. The conformations of the epoxide-bearing rings in various hydroxy epoxides are compared and shown to be similar.     

Triphenyltin Esters of N-(2-Carboxybenzylidene)anilines: Synthesis,Spectroscopic Characterization,X-ray Structure Analysis and Fungicidal Activity

Four triphenyltin carboxylates formulated as o- Ph₃SnOCOC₆H₄CH=N–Ar (Ar=C₆H₅; p -CH₃C₆H₄; o -CH₃C₆H₄; o -HOC₆H₄) were prepared and spectroscopically characterized. The crystal structure of o -Ph₃SnOCOC₆ H₄CH=NC₆H₅ indicates that the tin atom, in each of the two molecules comprising the asymmetric unit, exists in a distorted tetrahedral geometry owing to an intramolecular acyl O. . .Sn contact. These new triphenyltin carboxylates display marked toxicity against the fungus Ceratocystis ulmi .     

Fungicidal Activity of Some Organotin Compounds against Ceratocystis ulmi

Three series of organotin compounds were screened in vitro against Ceratocystis ulmi , the causative agent of Dutch elm disease. The series that were most active against this deadly fungus were those that contained the triphenyltin moiety. In addition, the fungicidal activity of the triphenyltin compounds were found to be independent of the anionic group attached to the tin atom. However, there was a marked increase in the activity of the triphenyltins when a biologically active group which did not dissociate upon dissolution was incorporated into the overall molecule.