288,319 research outputs found
A chain theorem for internally 4-connected binary matroids
No full textThis is the post-print version of the Article - Copyright @ 2011 ElsevierLet M be a matroid. When M is 3-connected, Tutte’s Wheels-and-Whirls Theorem proves that M has a 3-connected proper minor N with |E(M) − E(N)| = 1 unless M is a wheel or a whirl. This paper establishes a corresponding result for internally 4-connected binary matroids. In particular, we prove that if M is such a matroid, then M has an internally 4-connected proper minor N with |E(M) − E(N)| at most 3 unless M or its dual is the cycle matroid of a planar or Möbius quartic ladder, or a 16-element variant of such a planar ladder.This study was partially supported by the National Security Agency
Electrodynamics of colloids
No full textThe goal of the present study is to deepen the insight into the non-equilibrium properties of the electric double layer of colloidal systems. Of basic interest are the ionic mobilities in the different regions of the electric double layer as well as the potential at the plane of shear, i.e., the electrokinetic potential (ζ-potential). These parameters determine the colloidal behaviour under non-equilibrium conditions when the double layer is perturbed, for instance if external fields are applied and in particle-particle interaction during coagulation.One of the experimental methods utilized in this study is the measurement of the conductivity and the streaming potential of close-packed plugs of particles. From the resulting data we retrieved the dzeta.gif -potential, the surface conductivity, and the mobility of the counterions behind the plane of shear. The results are well comparable to those from the experimental low-frequency (LF) dielectric response of dilute dispersions of latex particles.The electrodynamic parameters can be influenced by adsorbing neutral polymer onto the surfaceIt is shown that the ζ-potential as well as the mobilities of the ions behind the plane of shear are decreased by the polymer film.The data in the above studies were successfully interpreted under the assumption of local equilibrium between the (complete) electric double layer and the adjacent electrolyte. However, there are double-layer conditions where this assumption is violated. In order to study these, we theoretically investigated the influence of relaxation of the compact part of the double layer (occupied inner-Helmholtz Stern layer) on the LF dielectric response and electrophoretic mobility. Possible relaxation mechanisms are retarded adsorption/desorption and ion migration along the surface. Along the same lines, the stability of the sol against coagulation was expressed in terms of the relaxation characteristics of the Stem layer.Chapter 2 dealt with the determination of plug conductivities and streaming potentials of a close-packed porous plug of latex particles for a number of indifferent electrolytes and ionic strengths. From these, the dzeta.gif -potentials and surface conductivities were computed. Monodisperse sulphate latex is an ideal model system since the surface charge consists of strong acidic groups so that a constant surface charge density is maintained throughout all the experiments. It was shown that the surface conductivity is insensitive to the ionic strength and that a large part of the countercharge is situated behind the shear plane. Furthermore, it was demonstrated that the ions in the double layer have a mobility close to the bulk mobility.In chapter 3 practical expressions were developed for the low-frequency (LF) dielectric response of dilute dispersions of spherical particles suspended in a binary electrolyte. The LF dielectric response of dilute sulphate latex dispersions was experimentally determined in the frequency range of 500 Hz to 500 kHz as a function of the ionic strength of suspending KCI. The resulting surface conductivities are insensitive to the ionic strength and practically identical to the values obtained by steady state methods (chapter 2). It was proposed that counterion motion can be retarded by specific interaction with the surface and by neutral polymer hairs present on the surface. In order to test the latter effect, the influence of the adsorption of uncharged polymer poly(ethylene) oxide onto the latex surface was investigated by means of LF spectroscopy, plug conductivities and streaming potentials of plugs in chapter 4. It was found that the polymer film on the surface reduces the surface conductivity. The drag on the ions in the polymer film can be described by considering the polymer layer as an inhomogeneous Brinkman fluid, characterised by a Darcy permeability which depends on the local polymer volume fraction. The polymer and counterion distributions were calculated from statistical self-consistent field lattice models.In order to investigate the influence of the surface charge density on the streaming potential and static conductivity, plugs of monodisperse spherical Stöber-silica particles were studied in chapter 5. Contrary to the latex, the surface charge density of silica can be controlled by pH. The high-charge silica plug showed more surface conduction than the low-charge plug since more mobile counterions are present in the double layer of the former. Stöber-silica particles are highly porous. For the relatively large particles under consideration, the major part of the countercharge is situated in the micropores of the particles. It was shown that these counterions do not contribute to the plug conductivity because of their low mobility.Chapter 6 analysed the dynamic aspects of particle electrophoresis. It was shown theoretically as well as experimentally that colloidal particles respond to an applied electric field much faster than does the liquid inside a measuring capillary. Therefore, it is possible to apply an alternating electric field with such a frequency that unwanted electroosmosis, induced by charge on the capillary wall, is suppressed, whereas the particles are still able to follow the field according to their dc mobility. This study illustrates that knowledge of the dynamics and the corresponding relaxation times is not only of purely scientific interest, but that it also offers solutions to very practical problems.In chapter 7 the influence of polarization of surface charge (or charge in an inner-Helmholtz layer) on the particle mobility, static conductivity, and low-frequency dielectric response was studied within the framework of the thin double-layer theory. It was shown that the characteristic times of relaxation processes in the Stern layer are accessible from dielectric spectroscopy. The relaxation phenomena under consideration are Stern-layer polarization via retarded adsorption/desorption and polarization via lateral transport in the Stem layer. The two processes may occur simultaneously. Since these relaxation processes are also relevant for particle-particle interaction, chapter 8 considered the implications for colloidal stability. In the situation of small transient disequilibrations of the surface charge, the stability could be expressed in terms of the characteristic times of surface charge relaxation. This allows the use of electrodynamic data obtained by dielectric spectroscopy in the interpretation of colloidal stability. On an even more rigorous level, the free energy of particle-particle interaction was also considered in the space of the two variables surface charge and separation. This formalism opens the way to investigate coagulation far from equilibrium
Evaluation of minor pathogen intramammary infection, susceptibility parameters, and somatic cell counts on the development of new intramammary infections with major mastitis pathogens
No full textMajor mastitis pathogens such as Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and coliforms are usually considered more virulent and damaging to the udder than minor mastitis pathogens such as Corynebacterium spp. and coagulase-negative staphylococci (CNS). The current literature comprises several studies (n=38) detailing analyses with conflicting results as to whether intramammary infections (IMI) with the minor pathogens decrease, increase, or have no effect on the risk of a quarter acquiring a new IMI (NIMI) with a major pathogen. The Canadian Bovine Mastitis Research Network has a large mastitis database derived from a 2-yr data collection on a national cohort of dairy farms, and data from this initiative were used to further investigate the effect of IMI with minor pathogens on the acquisition of new major pathogen infections (defined as a culture-positive quarter sample in a quarter that had been free of that major pathogen in previous samples in the sampling period). Longitudinal milk samplings of clinically normal udders taken over several 6-wk periods as well as samples from cows pre-dry-off and postcalving were used to this end (n=80,397 quarter milk samples). The effects of CNS and Corynebacterium spp. on the major mastitis pathogens Staph. aureus, Strep. uberis, Strep. dysgalactiae, and coliform bacteria (Escherichia coli and Klebsiella spp.) were investigated using risk ratio analyses and multilevel logistic regression models. Quarter-, cow- and herd-level susceptibility parameters were also evaluated and were able to account for the increased susceptibility that exists within herds, cows and quarters, removing it from estimates for the effects of the minor pathogens. Increased quarter-level susceptibility was associated with increased risk of major pathogen NIMI for all pathogens except the coliforms. Increased somatic cell count was consistently associated with elevated risk of new major pathogen infections, but this was assumed to be a result of low sensitivity of bacteriology to diagnose major pathogen NIMI expediently and accurately. The presence of CNS in the sample 2 samplings before the occurrence of a NIMI increased the odds of experiencing a Staph. aureus NIMI 2.0 times, making the presence of CNS a risk factor for acquiring a Staph. aureus NIMI. Even with this extensive data set, power was insufficient to make a definitive statement about the effect of minor pathogen IMI on the acquisition of major pathogen NIMI. Definitively answering questions of this nature are likely to require an extremely large data set dedicated particularly to minor pathogen presence and NIMI with major pathogens
Nelson N. Minor
No full textThe Oklahoma A&M College World War I Veterans collection captures the memories and experiences of the men and women of Oklahoma Agricultural and Mechanical College who served in World War I. In 1919, a project headed by Maude Cass, the editor of the 1919 Redskin; Professor Maroney of the Department of History; Margaret Walters, Librarian; and J.W. Cantwell, the College President, was undertaken to survey these veterans. The surveys were returned along with photographs, letters, and newspaper clippings documenting these veterans’ experiences during World War I
Introduction of a methodology- for reading plato's dialogues and analysis of the hippias minor
No full textThis work presents a reading of the whole and parts of Plato's Hippias Minor, independently of his other dialogues, on the premise that we cannot legitimately reduce Plato's characters' speech in a dialogue to his indirect speech. Hence the crux is analysis of Plato's interlocutors' interplay, but not his thought or Socrates' doctrine. The Hippias Minor properly provokes in readers intertwined paradoxical questions centred on two conversational conclusions: 'All and only false men are true' and 'All and only those are good who do injustice as they wish to'. In reply to Socrates' fishing question in Homeric context, Hippias, shackled by his boast of polymathy, allows the possibility of deceit as achievement, despite his persistence in the usual dispositional sense of honesty. This unanalysed idea of Hippias' and Socrates' rhetoric invites Hippias' public downfall. He is forced to accept the first conclusion by his commitment to the commissive sense of "speaking falsely' and the reciprocity of ability with actuality. Led into a respondent's role again by Socrates' long ex post facto speeches, Hippias resists Socrates' push towards the moral implication of the first conclusion; the preferability of whose who do injustice as they wish to. Socrates rhetorically pushes Hippias to the preferability by a circumventive arrangement of analogical topics and, further, by a trilemma argument on the assumption that justice is an ability and/or a knowledge. Each time Hippias affirms the propositions embodied in Socrates' questions, but he rootedly rejects the preferability. Socrates does not necessarily commit himself to the craft-analogy and justice as a knowledge, but, finally, questioning the existence of those doing justice as they wish to, scuttles the trilemma argument. Socrates' implication by this question is irreconcilable with his preceding presuppositions, but he suggests Hippias' inconsistency in his commitment to justice in an achievement sense
Ruptures of the pectoralis major and minor muscles
No full textThe pectoralis major (PMa) and pectoralis minor (PMi) muscles differ from each other in almost every aspect, despite the fact that they are localized very close to each other. While indirect traumatic injury is more common in PMa rupture, PMi avulsion via direct trauma injury is more frequently documented. Despite the low activity of the PMa during everyday movements, the patient’s cosmetic satisfaction and functional results are significantly better with surgical treatment compared to conservative treatment. On the other hand, conservatively treated patients after a PMi rupture have no functional restrictions and are therefore satisfied with the nonsurgical treatment. The surgical options for PMa ruptures are often explained in three main forms of treatment, the transosseous suture, the suture anchor and the unicortical or bicortical button. Due to the insufficient number of studies, a standard procedure has not yet been identified at the current time.Revisión por paresODS 3: Salud y BienestarODS 9: Industria, Innovación e InfraestructuraODS 17: Alianzas para lograr los objetivo
The Early Byzantine Domed Basilicas of West Asia Minor, An essay in Graphic Reconstruction
No full textThis paper investigates the methodology employed in the recent survey and reconstruction of the major Early Byzantine domed churches of west Asia Minor. This involved both the documentation of construction details as well as their interpretation by reference to coeval monuments elsewhere. Focusing on this methodology, the author explores techniques of graphic recording and the theoretical framework within which parallels with other buildings can inform the work of reconstruction. The detailed examination of two case studies illustrates the way in which seemingly random scraps of testimony were interpreted to provide evidence for the missing superstructure of the churches. These case studies also serve to explore the adaptation of the methodology to sites with different characteristics and help to assess the credibility of the resulting graphic reconstructions
CR immersions and Lorentzian geometry Part I: pseudohermitian rigidity of CR immersions
No full textWe study the geometry of the second fundamental form of pseudohermitian immersions among nondegenerate CR manifolds. In particular we study existence and uniqueness of pseudohermitian immersions of a strictly pseudoconvex CR manifold into an odd dimensional sphere, as determined by the pseudohermitian Gauss and Weingarten equations
From Mainstream to Minor and Back: The Irish Labour Party 1987-1992
No full textThis article charts the Irish Labour Party’s (ILP) journey from a minor to mainstream political party between 1987 and 1992. This is arguably the most turbulent period in the party’s electoral history, when the ILP performed significantly below its average result, before making unprecedented electoral gains. It identifies the factors which led to this fall and rise during the discussed period and reflects on the ILP’s place in the Irish party system arguing that the term ‘mainstream’ or ‘proximal mainstream’ party with regard to the ILP is perhaps more appropriate than the terms ‘major’ or ‘minor’ party, especially in view of its return to its usual level of support following the gains of 1992
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Influence of diluent alkyl substitution on the extraction of Am(III) and Eu(III) by a 6,6’-bis(1,2,4-triazin-3-yl)-2,2’-bipyridine ligand dissolved in alkylated cyclohexanone Diluents
No full textSeveral alkylated cyclohexanones were investigated as potential diluents for the selective extraction of Am(III) from Eu(III) from nitric acid solutions by the CyMe4-BTBP ligand. No significant extraction of either of the metal ions was observed for these diluents themselves. In the extractions from 1 M HNO3, 3-methylcyclohexanone and 4-methylcyclohexanone gave comparable results to cyclohexanone whereas in the extractions from 4 M HNO3, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone all gave superior results. For the monomethylated diluents, DAm and SFAm/Eu decreased in the order of alkyl substitution 2 > 4 ~ 3. However, alkyl substitution of cyclohexanone significantly slows down the extraction kinetics compared to cyclohexanone, and the position of alkyl substitution was found to play an important role in the solvents properties. 3-Methylcyclohexanone was identified as the most promising of the diluent
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