Median problems with positive and negative weights on cycles and cacti

This paper deals with facility location problems on graphs with positive and negative vertex weights. We consider two different objective functions: In the first one (MWD) vertices with positive weight are assigned to the closest facility, whereas vertices with negative weight are assigned to the farthest facility. In the second one (WMD) all the vertices are assigned to the nearest facility. For the MWD model it is shown that there exists a finite set of points in the graph which contains the locations of facilities in an optimal solution. Furthermore, algorithms for both models for the 2-median problem on a cycle are developed. The algorithm for the MWD model runs in linear time, whereas the algorithm for the WMD model has a time complexity of  O(n²)\mathcal{O}(n^{2}) .     

Preis-Promotion-Framing – Ein Überblick zum Stand der Forschung

This article reviews published literature and provides an overview on present empirical evidence about the framing of price promotions. Concerning explicit price reductions (discounts, coupons, rebates), the effects of advertised reference prices and different frames of price discounts (relative versus absolute price discount, objective versus tensile price claims) on consumers’ reactions are discussed. Furthermore, the article examines empirical results on implicit price reductions (volume packs, free extra products) as well as on sale signs and restrictions (e.g. purchase limits, time limits) as popular ways of framing a deal. The key findings point out that framing a price promotion in different ways can affect consumers’ perceptions and evaluations of the deal. Based on the reviewed literature, the concluding section provides managerial implications and an agenda for further research.     

Smoothing Time Series with Local Polynomial Regression on Time

Time series smoothers estimate the level of a time series at time t as its conditional expectation given present, past and future observations, with the smoothed value depending on the estimated time series model. Alternatively, local polynomial regressions on time can be used to estimate the level, with the implied smoothed value depending on the weight function and the bandwidth in the local linear least squares fit. In this article we compare the two smoothing approaches and describe their similarities. Through simulations, we assess the increase in the mean square error that results when approximating the estimated optimal time series smoother with the local regression estimate of the level.     

On the Detection of Contemporaneous Relationships Among Multiple Time Series

A study is carried out of a sampling from a half-normal and exponential distributions to develop a test of hypothesis on the mean. Although these distributions are similar, the corresponding uniformly most paerful test statistics are different. The exact distributions of these statistics my be written in terms of the incomplete gamma function. If the experimental data my be fitted by either distributions, it is advisable to carryout the test based on the half-normal distribution as it is generally more powerful than the one based on the exponential one.     

Measuring Institutions: Indicators of Political and Property Rights in Malawi

This paper constructs a new set of institutional indicators for Malawi. We develop indicators of political rights, of freehold, traditional (communitarian) and intellectual property rights, based on the Malawian legislative framework. In exploring the association between our rights measures and a range of indicators of socio-economic development, we obtain limited support for a modernization process for Malawi. On the one hand, the association between the rights variables can be interpreted as a modernization nexus, with a trade-off between legally anchored private property freehold rights and political rights on the one hand, and traditional forms of communal property rights on the other. By contrast, the association between rights and a range of socioeconomic development indicators gives a more nuanced picture. For social development measures property rights measures exercise a positive impact, regardless of whether they take the form of freehold or communitarian property rights. Economic development measures respond positively only to the freehold measure, and negatively to communitarian property rights. The socioeconomic development measures are negatively associated with political rights in Malawi over the last 40 years of the twentieth century.     

A Hybrid Geometric Phase II/III Clinical Trial Design based on Treatment Failure Time and Toxicity

The problem of comparing several experimental treatments to a standard arises frequently in medical research. Various multi-stage randomized phase II/III designs have been proposed that select one or more promising experimental treatments and compare them to the standard while controlling overall Type I and Type II error rates. This paper addresses phase II/III settings where the joint goals are to increase the average time to treatment failure and control the probability of toxicity while accounting for patient heterogeneity. We are motivated by the desire to construct a feasible design for a trial of four chemotherapy combinations for treating a family of rare pediatric brain tumors. We present a hybrid two-stage design based on two-dimensional treatment effect parameters. A targeted parameter set is constructed from elicited parameter pairs considered to be equally desirable. Bayesian regression models for failure time and the probability of toxicity as functions of treatment and prognostic covariates are used to define two-dimensional covariate-adjusted treatment effect parameter sets. Decisions at each stage of the trial are based on the ratio of posterior probabilities of the alternative and null covariate-adjusted parameter sets. Design parameters are chosen to minimize expected sample size subject to frequentist error constraints. The design is illustrated by application to the brain tumor trial.     

Soft Sovereignty,Rising Powers,and Subnational Foreign Policy-Making: The Case of India

Abstract

The rise of ‘new powers’ in international politics has been frequently associated with a re-emergence of traditional notions of sovereignty as a backlash against the weakening of nation-state sovereignty related to globalization. We argue that the coexistence of these trends has led to new forms of ‘soft sovereignty’. Soft sovereignty means that rising powers both gain and lose authority: From above, their freedom from interference within the international state system is strengthened due to their new status and influence. At the same time, rising powers’ governments are losing authority due to the rise of a multiplicity of sub and transnational actors from below. We apply the concept of soft sovereignty to the analysis of foreign policy-making in India as a least-likely case of a weakening of sovereignty from within a sovereignty-oriented rising power. The analysis of India's relations with Bangladesh and Sri Lanka reveals the huge impact that subnational governments have had on India's policies towards its South Asian neighbours over the past years. The dynamics observed in the case of India reflect many of the traits of current globalization processes, from regionalization to identity politics to the multiplication of actors in the conduct of foreign politics.     

A 14-h night-shift in the control room of a fire brigade

Abstract

All 29 operators in the control room of a fire brigade performed test sessions during work and leisure time at 2-h intervals on a day with a 14-h night-shift, a day off and a day with a 10-h morning shift. The test sessions consisted of a visual search choice reaction time test and two Sternberg memory search tests (1 or 5 letters had to be memorized). Furthermore, the operators recorded their oral temperature and their subjective alertness before each test session. The subject also kept a diary of work and sleep times for 14 days. The circadian rhythm of body temperature was hardly changed by a single night-shift. Parallel to the body temperature, the subjective alertness fell significantly during the night-shift reaching a minimum value at 06:00 h. The mean reaction times increased non-significantly at the end of the night-shift and the results of the two Sternberg memory search tests showed no significant trends. The sleep of the operators after the night-shift was on average reduced to 5 hs 34 min. The results of subjective rating of alertness and reaction time test are interpreted as effects of the combined influences of circadian rhythmicity, sleep loss and time on professional task. Most results support the conclusion that a 14-h night-shift without extensive breaks is not acceptable.     

A global risk assessment model for civil wars

In this study, we construct a multivariate model that assesses the risk of an outbreak of civil war in a country over a period of 5 years into the future. In addition to structural factors of state weakness, which have dominated the literature on civil war onset, this model includes repression of basic human rights to personal integrity – an important harbinger of wars to come – as an aspect of state behavior. Our aim is not to explore the causal factors of civil war onset, but to build a model that includes indicators that correlate with civil war outbreak and may be used to predict it. Based on two versions of the model – logit and neural network – out-of-sample risk assessments for three different time periods are generated and compared to the historical record of civil war outbreak during those years. In addition, the model’s ability to produce in-sample risk assessments over a 5-year period is tested. Finally, we compute truly predictive civil war risk assessments for all countries for which data are available, for the years 2008–2012. The analyses show that with a relatively simple model and based on publicly available data sources, meaningful civil war risk assessments can be computed. The quality of the predictions exceeds that of prominent studies, in which the risk of interstate war is assessed.