14,622 research outputs found
A new fractional derivative without singular kernel: Application to the modelling of the steady heat flow
In this article we propose a new fractional derivative without singular
kernel. We consider the potential application for modeling the steady
heat-conduction problem. The analytical solution of the fractional-order heat
flow is also obtained by means of the Laplace transform.Comment: 1 figur
Complexity of colouring problems restricted to unichord-free and \{square,unichord\}-free graphs
A \emph{unichord} in a graph is an edge that is the unique chord of a cycle.
A \emph{square} is an induced cycle on four vertices. A graph is
\emph{unichord-free} if none of its edges is a unichord. We give a slight
restatement of a known structure theorem for unichord-free graphs and use it to
show that, with the only exception of the complete graph , every
square-free, unichord-free graph of maximum degree~3 can be total-coloured with
four colours. Our proof can be turned into a polynomial time algorithm that
actually outputs the colouring. This settles the class of square-free,
unichord-free graphs as a class for which edge-colouring is NP-complete but
total-colouring is polynomial
Target costing: review of empirical studies in the automotive sector
This aim of this study is to compare the existing theory on the subject of targetcosting with practices reportedby empirical studies already performed in the automotive sector. We canidentify the following specific purpose: to analyze whether the characteristics of target costing,identified by the theory, are in line with what was reported by the empirical studies already performed in the automotive sector.Data collection was executed usinga review of empirical studies regardingthis topic in automotivecompanies. The data collected allowus to conclude that none of the companiessurveyed reports the use of thetarget costing model with the six characteristicsthe theory associates with it: price leads to cost, customer focus, product design focus, multidisciplinary teams;focus on the costs incurred during the product’slifecycle; involvement of the entire value chain
CCD Photometry of Delta Scuti stars 7 Aql and 8 Aql
As a continuation of the study of the Delta Scuti stars 7 Aql and 8 Aql; new
CCD photometric data were acquired in 2007. We present a period analysis on
these data that confirm the dominant modes detected in each star in the
framework of the STEPHI XII campaign in 2003.Comment: 9 pages, 7 figures, 2 tables; Accepted for publication in
Communications in Asteroseismology, Vol 153, 200
Actin assembly ruptures the nuclear envelope by prying the lamina away from nuclear pores and nuclear membranes in starfish oocytes.
The nucleus of oocytes (germinal vesicle) is unusually large and its nuclear envelope (NE) is densely packed with nuclear pore complexes (NPCs) stockpiled for embryonic development. We showed that breakdown of this specialized NE is mediated by an Arp2/3-nucleated F-actin 'shell' in starfish oocytes, in contrast to microtubule-driven tearing in mammalian fibroblasts. Here, we address the mechanism of F-actin-driven NE rupture by correlated live-cell, super-resolution and electron microscopy. We show that actin is nucleated within the lamina sprouting filopodia-like spikes towards the nuclear membranes. These F-actin spikes protrude pore-free nuclear membranes, whereas the adjoining membrane stretches accumulate NPCs associated with the still-intact lamina. Packed NPCs sort into a distinct membrane network, while breaks appear in ER-like, pore-free regions. Thereby, we reveal a new function for actin-mediated membrane shaping in nuclear rupture that is likely to have implications in other contexts such as nuclear rupture observed in cancer cells
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