scholarly journals Unions of a clique and a co-clique as star complements for non-main graph eigenvalues

2019 ◽  
Vol 35 ◽  
pp. 90-99 ◽  
Author(s):  
Zoran Stanic

Graphs consisting of a clique and a co-clique, both of arbitrary size, are considered in the role of star complements for an arbitrary non-main eigenvalue. Among other results, the sign of such a eigenvalue is discussed, the neigbourhoods of star set vertices are described, and the parameters of all strongly regular extensions are determined. It is also proved that, unless in a specified special case, if the size of a co-clique is fixed then there is a finite number of possibilities for our star complement and the corresponding non-main eigenvalue. Numerical data on these possibilities is presented.

2019 ◽  
pp. 002085231987878 ◽  
Author(s):  
Valérie Pattyn ◽  
Sonja Blum ◽  
Ellen Fobé ◽  
Mirjam Pekar-Milicevic ◽  
Marleen Brans

Research on policy-advisory systems worldwide has shown that historically dominant sources of advice traditionally located in-house to the government have been increasingly supplemented by other actors and outside knowledge. However, the vast majority of research has concentrated on the anglophone context. Yet, countries with a consensus-seeking, neo-corporatist tradition provide a special case in terms of policy advice and merit more scholarly attention. What counts as evidence in these countries is the expert rationality of institutional representatives. The position and role of academic research in consensus-based systems is unclear, and is the focus of this article. Can we observe commonalities across consensus-style countries, or do differences prevail? We investigate two typical consensus-seeking countries: Belgium and Germany. To examine the supply side of policy advice, the article reviews current evidence regarding their policy-advisory systems. For the demand side, we present insights from a survey among federal ministerial officials. We find common trends between the two cases but their nature and extent are idiosyncratic. In Belgium, the supply of and demand for academic policy advice is comparatively lower, while the German case exhibits more change in the advisory landscape and institutionalisation of the supply of and demand for academic research. Points for practitioners   • Countries with a consensus-seeking, neo-corporatist tradition provide a special case in terms of policy advice.   • The findings suggest that there are common trends but their nature and extent are idiosyncratic.   • In Belgium, the supply of and demand for academic advice is comparatively lower.   • Germany’s policy-advisory landscape exhibits more change and institutionalisation of the supply of and demand for academic research.


2021 ◽  
pp. 1-29
Author(s):  
DREW HEARD

Abstract Greenlees has conjectured that the rational stable equivariant homotopy category of a compact Lie group always has an algebraic model. Based on this idea, we show that the category of rational local systems on a connected finite loop space always has a simple algebraic model. When the loop space arises from a connected compact Lie group, this recovers a special case of a result of Pol and Williamson about rational cofree G-spectra. More generally, we show that if K is a closed subgroup of a compact Lie group G such that the Weyl group W G K is connected, then a certain category of rational G-spectra “at K” has an algebraic model. For example, when K is the trivial group, this is just the category of rational cofree G-spectra, and this recovers the aforementioned result. Throughout, we pay careful attention to the role of torsion and complete categories.


Author(s):  
Katarzyna Bentkowska

Abstract This paper explains how informal institutions influence the reaction to the COVID-19 pandemic and the response to formal restrictions. I claim that it is not enough to introduce countermeasures, as individuals must follow them if they are to be effective. The acceptance of such measures is reflected in individuals' degrees of mobility decrease and contact reduction, the aims of governmental restrictions. I identify a group of attitudes connected with individuals' responses that differ across countries. They are associated with social relations and approaches to dealing with problems. The analysis confirms that formal restrictions can be seen as successful only if they are supported by strong informal institutions. In some cases, they even define individuals' reactions more than formal recommendations. The findings are useful not only for explaining the special case of reaction to pandemic restrictions but also for investigating what generally determines individuals' compliance with formal rules.


2008 ◽  
Vol 18 (08) ◽  
pp. 1409-1441 ◽  
Author(s):  
AVNER FRIEDMAN ◽  
BEI HU

The cells in a tissue occupying a region Ωt are divided according to their cycling phase. The density pi of cells in phase i depends on the spatial variable x, the time t, and the time si since the cells entered in phase i. The pi(x, t, si) and the oxygen concentration w(x, t) satisfy a system of PDEs in Ωt, and the boundary of Ωt is a free boundary. We denote by [Formula: see text] the oxygen concentration on the free boundary and consider the radially symmetric case, so that Ωt = {r < R(t)}. We prove that R(t) is always bounded; furthermore, if [Formula: see text] is small, then R(t) → 0 as t → ∞, and if [Formula: see text] is large, then R(t) ≥ c > 0 for all t. Finally, we prove the existence and uniqueness of a stationary solution in a special case.


2021 ◽  
Vol 5 (2) ◽  
pp. 268
Author(s):  
Sarlota Singerin

Teaching skills are one of the skills that must be possessed by a teacher. Whether or not the pedagogical competence possessed by teachers can be seen from the quality of school performance. Supervision still tends to lead to inspection. So far, the implementation of academic supervision is considered effective. In order for the Academic Supervision to provide objective and detailed results, collaborative self-evaluation is carried out, namely peer evaluation to find teacher strengths that need to be maintained and deficiencies that must be corrected. This study aims to determine the effect of collaboration-based Academic Supervision model with Peer Evaluation Approach to Improve Pedagogical Competence and Quality of School Performance: The Role of Principal's Motivation as Moderation Variable. This research is a quantitative study with numerical data analyzed using the Structural Equation Model (SEM) assisted by the Smart PLS application. The results showed that Academic Supervision has an effect on Pedagogical Competence with a P-Value of 0.000 (p <0.05). Academic Supervision affects the Quality of Performance with a P value of 0.000 (p <0.05). motivation is able to moderate positively pedagogical competence with a P value of 0.032 (p <0.05). Motivation is not able to moderate supervision of the quality of performance with a P value of 0.138 (p> 0.05). Supervision is able to explain the Pedagogical Competence (Y1) variable of 69.4%. Supervision is able to explain the Performance Quality variable (Y2) of 40.1%. The principal should be able to periodically monitor the learning carried out by the teacher in the classroom, so that the principal knows the problems faced by the teacher in learning. Researchers who want to research further on this topic can use other variables and a wider sample.


Author(s):  
Nathalie Ramos ◽  
Christoph Mittermeier ◽  
Josef Kiendl

AbstractA good understanding of the heat transfer in fused filament fabrication is crucial for an accurate stress prediction and subsequently for repetitive, high-quality printing. This work focuses on two challenges that have been presented when it comes to the accuracy and efficiency in simulating the heat transfer in the fused filament fabrication process. With the prospect of choosing correct thermal boundary conditions expressing the natural convection between printed material and its environment, values for the convective heat transfer coefficient and ambient temperature were calibrated through numerical data fitting of experimental thermal measurements. Furthermore, modeling simplifications were proposed for an efficient numerical discretization of infill structures. Samples were printed with varying infill characteristics, such as varying air void size, infill densities and infill patterns. Thermal measurements were performed to investigate the role of these parameters on the heat transfer and based on these observations, possible modeling simplifications were studied in the numerical simulations.


Author(s):  
S. B. Kostenko ◽  
I. Y. Hangur ◽  
I. V. Sorokopud ◽  
M. Y. Goncharuk-Khomyn ◽  
G. N. Nakashidze

Summary. Among the proposed USPHS criteria approved by FDI, the level of gloss and polishing of restorations plays a key role in preventing not only such complications  as disocorporations or changes in their texture in the future, but also preventing secondary caries and sealing disintegration, since areas with high roughness play the role of retention points for the accumulation of bacterial plaque and the further progression of the above-described complications.The aim of the study – to analyze the methods for assessing the quality of polishing composite restorations and to determine the role of influence roughness factor of their surface on the prediction of their functioning and change of color stability parameters, formation of biofilm and shine.Materials and Methods. Search of publications related to the topic of this analysis was conducted by the Google Scholar search engine by the keywords "roughness", "polishing", "composite restorations" and their analogues in English. The depth of search, taking into account the age of key articles, determined by the level of their citation in later periodicals, did not exceed 15 years. In order to organize the received data, Microsoft Excel 2016 (Microsoft Office) table editor was used to group  pre-selected articles based on the results of the provided content analysis.Results and Discussion. In the course of the analysis, it was established that the basic laboratory methods for assessing the roughness of the restoration surface, as an indicator of the quality of polishing, are atomic force microscopy, scanning electron microscopy and profilometry. Most often, in order to verify the aforementioned parameter in the analyzed studies, the Ra value of mean arithmetic deviation of the profile was used, on the basis of which analysis it was possible to determine the dependence of the possibilities for achieving the corresponding level of restoration polishing on the structure of the composite material used, the system and phases of polishing, and the tribological nature of the interaction of the polishing system and the surface of the restoration.Conclusions. The results of the analysis show that the data obtained in the course of previous clinical and laboratory studies dedicated to the effect of polishing on various restoration parameters are debatable and a more specific systematization is required, with the selection of the investigated aspects of brightness, roughness, color stability and functional prediction changes due to the polishing method in separate independent subjects for research, with further phased combination of them after obtaining unambiguous numerical data, subjected to appropriate objective interpretation.


2021 ◽  
Vol 13 (2) ◽  
pp. 289-362
Author(s):  
Bruno Currie

Abstract This paper offers a reappraisal of the role of intertextuality in fifth-century BCE epinician poetry by means of a comparison with the role of intertextuality in all of early Greek hexameter poetry, ‘lyric epic’, and fifth-century BCE tragedy and comedy. By considering the ways in which performance culture as well as the production of written texts affects the prospects for intertextuality, it challenges a scholarly view that would straightforwardly correlate intertextuality in early Greek poetry with an increasing use and dissemination of written texts. Rather, ‘performance rivalry’ (a term understood to encompass both intra- and intergeneric competition between poetic works that were performed either on the same occasion or on closely related occasions) is identified as a plausible catalyst of intertextuality in all of the poetic genres considered, from the eighth or seventh century to the fifth century BCE. It is argued that fifth-century epinician poetry displays frequent, fine-grained, and allusive intertextuality with a range of early hexameter poetry: the Iliad, the poems of the Epic Cycle, and various ‘Hesiodic’ poems – poetry that in all probability featured in the sixth-fifth century BCE rhapsodic repertoire. It is also argued that, contrary to what is maintained in some recent Pindaric scholarship, there is no comparable case to be made for a frequent, significant, and allusive intrageneric intertextuality between epinician poems: in this respect, the case of epinician makes a very striking contrast with epic, tragedy, and comedy – poetic genres to which intrageneric intertextuality was absolutely fundamental. It is suggested that the presence or absence of intrageneric intertextuality in the genres in question is likely to be associated with the presence or absence of performance rivalry. A further factor identified as having the potential to inhibit intrageneric intertextuality in epinician is the undesirability of having one poem appear to be ‘bettered’ by another in a genre were all poems were commissioned to exalt individual patrons. This, again, is a situation that did not arise for epic, tragedy, or comedy, where a kind of competitive or ‘zero-sum’ intertextuality could be (and was) unproblematically embraced. Intertextuality in epinician thus appears to present a special case vis-à-vis the other major poetic genres of early Greece, whose workings can both be illuminated by consideration of the workings of intertextuality in epic, tragedy, and comedy, and can in turn illuminate something of the workings of intertextuality in those genres.


2019 ◽  
pp. 246-260
Author(s):  
Paul Humphreys

An agent- based model of social dynamics is introduced using a deformable fitness landscape, and it is shown that in certain clearly specifiable situations, strategies that are different from utility maximization outperform utility maximizers. Simulation results are presented and intuitive interpretations of the results provided. The situations considered occur when individuals' actions affect the outcomes for other agents and endogenous effects are dominant. The Tragedy of the Commons is merely a special case of this. Arguments are given that constraints are to be encouraged in some circumstances. The appropriate role of constraints in various types of society is assessed and their use justified in identifiable types of situations.


1900 ◽  
Vol 39 (2) ◽  
pp. 491-506 ◽  
Author(s):  
Tait

The first instalment of this paper was devoted in great part to the general subject involved in its title, but many of the illustrations were derived from the special case of the flight of a golf-ball. Since it was read I have endeavoured, alike by observation and by experiment, to improve my numerical data for this interesting application, particularly as regards the important question of the coefficient of resistance of the air. As will be seen, I now find a value intermediate to those derived (by taking average estimates of the mass and diameter of a golf-ball) from the results of Robins and of Bashforth. This has been obtained indirectly by means of a considerable improvement in the apparatus by which I had attempted to measure the initial speed of a golf-ball. I have, still, little doubt that the speed may, occasionally, amount to the 300, or perhaps even the 350, foot-seconds which I assumed provisionally in my former paper:—but even the first of these is a somewhat extravagant estimate; and I am now of opinion that, even with very good driving, an initial speed of about 240 is not often an underestimate, at least in careful play. From this, and the fact that six seconds at least are required for a long carry (say 180 yards), I reckon the “terminal velocity” at about 108, giving v2/360 as the resistance-acceleration.


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