To advance understanding of the entrepreneurship process in developing economies, this article evaluates whether registered enterprises that initially avoid the cost of registration, and focus their ...resources on overcoming other liabilities of newness, lay a stronger foundation for subsequent growth. Analyzing World Bank Enterprise Survey data across 127 countries, and controlling for other firm performance determinants, registered enterprises that started up unregistered and spent longer operating unregistered are revealed to have significantly higher subsequent annual sales, employment, and productivity growth rates compared with those that registered from the outset. The theoretical and policy implications are then discussed.
In this paper we study lower bounds in a unified way for a large family of topological indices, including the first variable Zagreb index M1α. Our aim is to obtain sharp inequalities and characterize ...the corresponding extremal graphs. The main results provide lower bounds for several vertex-degree-based topological indices. These bounds are new even for the first Zagreb, the inverse and the forgotten indices.
Hyperbolicity of Direct Products of Graphs Carballosa, Walter; De la Cruz, Amauris; Martínez-Pérez, Alvaro ...
Symmetry (Bandung),
07/2018, Letnik:
10, Številka:
7
Journal Article
Recenzirano
Odprti dostop
It is well-known that the different products of graphs are some of the more symmetric classes of graphs. Since we are interested in hyperbolicity, it is interesting to study this property in products ...of graphs. Some previous works characterize the hyperbolicity of several types of product graphs (Cartesian, strong, join, corona and lexicographic products). However, the problem with the direct product is more complicated. The symmetry of this product allows us to prove that, if the direct product G1×G2 is hyperbolic, then one factor is bounded and the other one is hyperbolic. Besides, we prove that this necessary condition is also sufficient in many cases. In other cases, we find (not so simple) characterizations of hyperbolic direct products. Furthermore, we obtain good bounds, and even formulas in many cases, for the hyperbolicity constant of the direct product of some important graphs (as products of path, cycle and even general bipartite graphs).
In the election of a hierarchical clustering method, theoretic properties may give some insight to determine which method is the most suitable to treat a clustering problem. Herein, we study some ...basic properties of two hierarchical clustering methods:
α
-unchaining single linkage or
SL
(
α
) and a modified version of this one,
SL∗
(
α
). We compare the results with the properties satisfied by the classical linkage-based hierarchical clustering methods.
The concept of geometric–arithmetic index was introduced in the chemical graph theory recently, but it has shown to be useful. The aim of this paper is to obtain new inequalities involving the ...geometric–arithmetic index
G
A
1
and characterize graphs extremal with respect to them.
Vaccination can sufficiently ameliorate the coronavirus disease-2019 (COVID-19). Investigating what factors influence vaccine uptake may benefit ongoing vaccination efforts (e.g. booster injections, ...annual vaccination). The present study expanded Protection Motivation Theory with possible factors including perceived knowledge, adaptive responses, and maladaptive responses to develop a proposed model investigating vaccine uptake among United Kingdom (UK) and Taiwan (TW) populations. An online survey collected responses from UK (n = 751) and TW (n = 1052) participants (August to September, 2022). The results of structural equation modeling (SEM) showed that perceived knowledge was significantly associated with coping appraisal in both samples (standardized coefficient β = 0.941 and 0.898; p < .001). Coping appraisal was correlated with vaccine uptake only in the TW sample (β = 0.319, p < .05). Multigroup analysis showed there were significant differences between the path coefficients of perceived knowledge to coping and threat appraisals (p < .001), coping appraisal to adaptive and maladaptive responses (p < .001), as well as threat appraisal to adaptive response (p < .001). Such knowledge may improve vaccine uptake in Taiwan. The potential factors for the UK population require further investigation.
A graph is chordal if every induced cycle has exactly three edges. A vertex separator set in a graph is a set of vertices that disconnects two vertices. A graph is δ -hyperbolic if every geodesic ...triangle is δ -thin. In this paper, we study the relation between vertex separator sets, certain chordality properties that generalize being chordal and the hyperbolicity of the graph. We also give a characterization of being quasi-isometric to a tree in terms of chordality and prove that this condition also characterizes being hyperbolic, when restricted to triangles, and having stable geodesics, when restricted to bigons.
This article investigates the relationship between the sharing of domestic tasks in dual-earner mixed-sex couples and the use of paid domestic services. Using results from a small-scale survey of the ...domestic outsourcing practices of employees of a large service-sector organisation in the UK, we find that in households: full-time working by women and presence of younger children is positively associated with the use of paid domestic services; there is no association between the gender division of traditionally female domestic tasks carried out within the couple and use of paid services; but in contrast, greater male involvement in traditionally male and traditionally gender-neutral tasks is positively associating with using paid domestic services. These findings tentatively suggest that a new arrangement may be emerging in which some couples address a heavy workload and a desire for a less traditional division of domestic labour by men participating more in close-ended domestic tasks and outsourcing the more time-consuming tasks traditionally undertaken by women to paid-service providers.
To evaluate critically the dominant discourse that consumers acquiring goods and services in the informal economy are rational economic actors seeking a lower price, the results of a 2007 ...Eurobarometer survey involving 26,659 face-to-face interviews in 27 European Union member states form the basis for analysis. The finding is that achieving a lower price is the sole motive for just 44% of informal economy purchases, one of several rationales in 28% of transactions, and not a rationale in 28% of acquisitions. Consumers also use the informal economy to circumvent the shortcomings of the formal economy in terms of the availability, speed, and quality of goods and services provision, as well as for social and redistributive reasons, with multilevel mixed-effects logit regression analysis revealing how the prevalence of these rationales significantly varies across populations. The paper concludes by discussing the theoretical and policy implications of the findings.
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