On the Directional Derivative of Kemeny's Constant

In a connected graph, Kemeny's constant gives the expected time of a random walk from an arbitrary vertex $x$ to reach a randomly-chosen vertex $y$. Because of this, Kemeny's constant can be interpreted as a measure of how well a graph is connected. It is generally unknown how the addition or removal of edges affects Kemeny's constant. Inspired by the directional derivative of the normalized Laplacian, we derive the directional derivative of Kemeny's constant for several graph families. In addition, we find sharp bounds for the directional derivative of an eigenvalue of the normalized Laplacian and bounds for the directional derivative of Kemeny's constant

Aquilegia, Vol. 26 No. 2, March-April 2002: Newsletter of the Colorado Native Plant Society

https://epublications.regis.edu/aquilegia/1092/thumbnail.jp

Religious socialisation and fertility: transition to third birth in the Netherlands

Although previous studies have demonstrated that religious people in Europe have larger families, the role played by religious socialisation in the context of contemporary fertility behaviour has not yet been analysed in detail. This contribution specifically looks at the interrelation between religious socialisation and current religiosity and their impact on the transition to the third child for Dutch women. It is based on data of the first wave of the Netherlands Kinship Panel Study (2002–2004) and uses event history analysis. The transitions to first, second and third birth are modelled jointly with a control for unobserved heterogeneity. The findings provide evidence for an impact of women’s current church attendance as well as religious socialisation measured by their fathers’ religious affiliation, when they were teenagers. A religious family background remains influential even when a woman has stopped attending church. The effects of religious indicators strengthen over cohorts. Moreover, the combined religious make-up of the respondent’s parents also significantly determines the progression to the third child.S’il est bien établi que les croyants en Europe ont plus d’enfants que les autres, le rôle de la socialisation religieuse dans le contexte de la fécondité contemporaine n’a pas encore été analysé à ce jour. Cette étude s’intéresse au lien entre la socialisation religieuse et la religiosité actuelle, et à leur impact sur la probabilité d’agrandissement de deux à trois enfants de la descendance des femmes néerlandaises. Les données exploitées sont celles de la première vague du Panel Néerlandais d’Etude de la Parenté (the Netherlands Kinship Panel Study, 2002–2004). A l’aide des techniques de l’analyse des biographies, les probabilités d’agrandissement de rang 1, rang 2 et rang 3 ont été modélisées de façon conjointe, en contrôlant l’hétérogénéité non observée. Les résultats mettent en évidence l’impact de la fréquentation actuelle de l’église par les femmes et de leur socialisation religieuse, mesurée par l’appartenance religieuse de leur père quand elles étaient adolescentes. Il apparaît que la religiosité du contexte familial exerce une influence, même quand la femme ne fréquente plus l’église, et que les effets des indicateurs de pratique religieuse se renforcent d’une génération à l’autre. Enfin, l’appartenance religieuse conjointe des parents de la femme détermine significativement la probabilité d’avoir un troisième enfant

A Modified Experimental Hut Design for Studying Responses of Disease-Transmitting Mosquitoes to Indoor Interventions: The Ifakara Experimental Huts

Differences between individual human houses can confound results of studies aimed at evaluating indoor vector control interventions such as insecticide treated nets (ITNs) and indoor residual insecticide spraying (IRS). Specially designed and standardised experimental huts have historically provided a solution to this challenge, with an added advantage that they can be fitted with special interception traps to sample entering or exiting mosquitoes. However, many of these experimental hut designs have a number of limitations, for example: 1) inability to sample mosquitoes on all sides of huts, 2) increased likelihood of live mosquitoes flying out of the huts, leaving mainly dead ones, 3) difficulties of cleaning the huts when a new insecticide is to be tested, and 4) the generally small size of the experimental huts, which can misrepresent actual local house sizes or airflow dynamics in the local houses. Here, we describe a modified experimental hut design - The Ifakara Experimental Huts- and explain how these huts can be used to more realistically monitor behavioural and physiological responses of wild, free-flying disease-transmitting mosquitoes, including the African malaria vectors of the species complexes Anopheles gambiae and Anopheles funestus, to indoor vector control-technologies including ITNs and IRS. Important characteristics of the Ifakara experimental huts include: 1) interception traps fitted onto eave spaces and windows, 2) use of eave baffles (panels that direct mosquito movement) to control exit of live mosquitoes through the eave spaces, 3) use of replaceable wall panels and ceilings, which allow safe insecticide disposal and reuse of the huts to test different insecticides in successive periods, 4) the kit format of the huts allowing portability and 5) an improved suite of entomological procedures to maximise data quality