Packing trees in communication networks

Given an undirected edge-capacitated graph and given (possibly) different subsets of vertices, we consider the problem of selecting a maximum (weighted) set of Steiner trees, each tree spanning a subset of vertices, without violating the capacity constraints. This problem is motivated by applications in multicast communication networks. We give an integer linear programming (ILP) formulation for the problem, and observe that its linear programming (LP) relaxation is a fractional packing problem with exponentially many variables and a block (sub-)problem that cannot be solved in polynomial time. To this end, we take an r-approximate block solver (a weak block solver) to develop a (1−ε)/r-approximation algorithm for the LP relaxation. The algorithm has a polynomial coordination complexity for any ε∈(0,1). To the best of our knowledge, this is the first approximation result for fractional packing problems with only weak block solvers (with arbitrarily large approximation ratio) and a coordination complexity that is polynomial in the input size. This leads also to an approximation algorithm for the underlying tree packing problem. Finally, we extend our results to an important multicast routing and wavelength assignment problem in optical networks, where each Steiner tree is to be assigned one of a limited set of given wavelengths, so that trees crossing the same fiber are assigned different wavelengths. A preliminary version of this paper appeared in the Proceedings of the 1st Workshop on Internet and Network Economics (WINE 2005), LNCS, vol. 3828, pp. 688–697. Research supported by a MITACS grant for all the authors, an NSERC post doctoral fellowship for the first author, the NSERC Discovery Grant #5-48923 for the second and fourth author, NSERC Discovery Grant #15296 for the third author, the Canada Research Chair Program for the second author, and an NSERC industrial and development fellowship for the fourth author.     

A note on the equivariant estimation of an exponential scale using progressively censored data

We consider the problem of estimating the scale parameter θ$\theta$ of the shifted exponential distribution with unknown location based on a type II progressively censored sample. Under a large class of bowl-shaped loss functions, a smooth estimator, that dominates the minimum risk equivariant estimator of θ$\theta$, is proposed. A numerical study is performed and shows that the improved estimator yields significant risk reduction over the MRE.     

Related party transactions and audit fees: the role of the internal audit function

Related party transactions (RPTs) are viewed as genuine transactions that rationally fulfil other economic demands of a company. However, RPTs can also be used to transfer wealth from minority shareholders to controlling shareholders. The existence of such transactions may deteriorate financial reporting quality, increase audit risk, and as a result increase audit fees. This study examines the relationship between RPTs and audit fees in Malaysia, where ownership is often concentrated within a controlling family and corporate governance mechanisms are poor. It also investigates the moderating effect of the internal audit function (IAF) on this relationship. We find that external auditors base their fees on the types of RPTs undertaken. Specifically, our results show that audit fees are higher for firms that undertake RPTs involving the sale and purchase of assets, goods, and services. We also document that external auditors rely on the IAF, and thus their fees are lower for firms that undertake RPTs and that have made a large investment in an IAF. Our study is the first to provide evidence that RPTs in Malaysian firms may be abused as a channel to facilitate tunnelling and that the IAF plays a vital role in controlling such transactions.     

Does International Migration Affect Labor Supply,Non‐farm Diversification and Welfare of Households? Evidence from Egypt

This study examines the effect of international migration in Egypt using fixed‐effect regressions and panel data from Egypt Labour Market Panel Surveys in 2006 and 2012. We find that men and people with higher education are more likely to migrate than women and people with lower education. Middle‐aged people are also more likely to migrate than young or old people. International migration does not seem to affect the overall employment of remaining members of migrant‐sending households. However, it tends to increase the self‐employed work of members of migrant‐sending households. Finally, international migration also helps migrant‐sending households increase their wealth index. Remittances are used to improve living conditions (housing) and purchase more assets and durables. This finding supports the theory as well as the policy to increase migration as a way to stabilize consumption and reduce poverty in low income countries.     

The Secular and the Religious in the Management of Islam in Singapore

This article examines the Singaporean model of “secularism” and its impact on the relations between the Singaporean government and the minority Muslim community in Singapore. While the Singaporean state defines itself as secular, its policies do not depict a strict dichotomy between religion and state. This paper argues that the obscure nature of secularism in Singapore has led to tensions on several issues between the government and Muslim community due to differing perceptions of what Singaporean secularism means. The first section of the paper deals with the concept of secularism as defined by the Singaporean state and examine the historical factors that led to the provision of special rights to Muslims in Singapore. The paper will then analyse the legal positions of institutions such as the Islamic Religious Council of Singapore (Majlis Ugama Islam Singapura, MUIS) and the Syariah court which are tasked with managing Islamic affairs in Singapore. Lastly, the paper will analyse how the unique definition of secularism in Singapore led to tensions between the government and the Muslim community. These cases included the headscarf controversy that erupted in 2002 and 2013, the madrasah controversy in 1999, foreign policy issues and terrorism. The paper concludes by drawing a trajectory of the future relations between the Singaporean government and the Muslim community.     

Redistributed Manufacturing and the Impact of Big Data: A Consumer Goods Perspective

Abstract

Digitalization and the growth of big data promise greater customization as well as change in how manufacturing is distributed. Yet, challenges arise in applying these new approaches in consumer goods industries that often emphasize mass production and extended supply chains. We build a conceptual framework to explore whether big data combined with new manufacturing technologies can facilitate redistributed manufacturing (RDM). Through analysis of 24 consumer goods industry cases using primary and secondary data, we investigated evolving manufacturing configurations, their underlying drivers, the role of big data applications, and their impact on the redistribution of manufacturing. We find some applications of RDM concepts, although in other cases existing manufacturing configurations are leveraged for high volume consumer goods products through big data analytics and market segmentation. The analysis indicates that the framework put forward in the paper has broader value in organizing thinking about emerging interrelationships between big data and manufacturing.     

Explicit expressions for gamma spacings and their moments

This work is concerned with the distributions of spacings from a two-parameter gamma distribution, when the shape parameter is a positive integer (or Erlang Distribution). We express the probability density functions of spacings and their moments in closed forms that are easy to implement using computer algebra systems like Mathematica.     

Value-at-risk estimation by LS-SVR and FS-LS-SVR based on GAS model

ABSTRACT

Conditional risk measuring plays an important role in financial regulation and depends on volatility estimation. A new class of parameter models called Generalized Autoregressive Score (GAS) model has been successfully applied for different error's densities and for different problems of time series prediction in particular for volatility modeling and VaR estimation. To improve the estimating accuracy of the GAS model, this study proposed a semi-parametric method, LS-SVR and FS-LS-SVR applied to the GAS model to estimate the conditional VaR. In particular, we fit the GAS(1,1) model to the return series using three different distributions. Then, LS-SVR and FS-LS-SVR approximate the GAS(1,1) model. An empirical research was performed to illustrate the effectiveness of the proposed method. More precisely, the experimental results from four stock indexes returns suggest that using hybrid models, GAS-LS-SVR and GAS-FS-LS-SVR provides improved performances in the VaR estimation.     

Perinatal and social factors predicting caesarean birth in a 2004 Australian birth cohort

Background

The proportion of babies born by caesarean section in Australia has almost doubled over the last 25 years. Factors known to contribute to caesarean such as higher maternal age, mothers being overweight or obese, or having had a previous caesarean do not completely account for the increased rate and it is clear that other influences exist.