Contraction blockers for graphs with forbidden induced paths.

We consider the following problem: can a certain graph parameter of some given graph be reduced by at least d for some integer d via at most k edge contractions for some given integer k? We examine three graph parameters: the chromatic number, clique number and independence number. For each of these graph parameters we show that, when d is part of the input, this problem is polynomial-time solvable on P4-free graphs and NP-complete as well as W[1]-hard, with parameter d, for split graphs. As split graphs form a subclass of P5-free graphs, both results together give a complete complexity classification for Pℓ-free graphs. The W[1]-hardness result implies that it is unlikely that the problem is fixed-parameter tractable for split graphs with parameter d. But we do show, on the positive side, that the problem is polynomial-time solvable, for each parameter, on split graphs if d is fixed, i.e., not part of the input. We also initiate a study into other subclasses of perfect graphs, namely cobipartite graphs and interval graphs

The Attraction of Foreign Manufacturing Investments: Investment Promotion and Agglomeration Economies

We study Japanese investments between 1980 and 1992 to assess the effectiveness of state promotion efforts in light of strong agglomeration economies in Japanese investment. Two policy variables are consistently shown to influence the location of investment - foreign trade zones and labor subsidies. We use simulations to explore the impact these policies had on the geographic distribution of Japanese investment. The simulations reveal that in aggregate promotion programs largely offset each other; however, unilateral withdrawal of promotion causes individual states to lose substantial amounts of foreign investment.

The role of SLR and LLR in relativity

While General Relativity has been adopted as the standard theory of relativity, there are alternative theories, with important implications for gravitational physics, which can only be discounted with tests of sufficient accuracy. In addition to its contributions to lunar and solar system dynamics, Lunar Laser Ranging, in combination with other solar system data continues to refine some important limits. Satellite laser ranging tracking of geodetic satellites can provide similar tests, but the accuracy is usually limited by gravitational and nongravitational perturbations

The Wendelstein Calar Alto Pixellensing Project (WeCAPP): the M31 Nova catalogue

We present light curves from the novae detected in the long-term, M31 monitoring WeCAPP project. The goal of WeCAPP is to constrain the compact dark matter fraction of the M31 halo with microlensing observations. As a by product we have detected 91 novae benefiting from the high cadence and highly sensitive difference imaging technique required for pixellensing. We thus can now present the largest CCD and optical filters based nova light curve sample up-to-date towards M31. We also obtained thorough coverage of the light curve before and after the eruption thanks to the long-term monitoring. We apply the nova taxonomy proposed by Strope et al. (2010) to our nova candidates and found 29 S-class novae, 10 C-class novae, 2 O-class novae and 1 J-class nova. We have investigated the universal decline law advocated by Hachichu and Kato (2006) on the S-class novae. In addition, we correlated our catalogue with the literature and found 4 potential recurrent novae. Part of our catalogue has been used to search for optical counter-parts of the super soft X-ray sources detected in M31 (Pietsch et al. 2005). Optical surveys like WeCAPP, and coordinated with multi-wavelength observation, will continue to shed light on the underlying physical mechanism of novae in the future.Comment: 15 pages, 15 figures, 7 tables, A&A accepted for publication. The appendix is stored in the Data Conservanc

An improved model for the Earth's gravity field

An improved model for the Earth's gravity field, TEG-1, was determined using data sets from fourteen satellites, spanning the inclination ranges from 15 to 115 deg, and global surface gravity anomaly data. The satellite measurements include laser ranging data, Doppler range-rate data, and satellite-to-ocean radar altimeter data measurements, which include the direct height measurement and the differenced measurements at ground track crossings (crossover measurements). Also determined was another gravity field model, TEG-1S, which included all the data sets in TEG-1 with the exception of direct altimeter data. The effort has included an intense scrutiny of the gravity field solution methodology. The estimated parameters included geopotential coefficients complete to degree and order 50 with selected higher order coefficients, ocean and solid Earth tide parameters, Doppler tracking station coordinates and the quasi-stationary sea surface topography. Extensive error analysis and calibration of the formal covariance matrix indicate that the gravity field model is a significant improvement over previous models and can be used for general applications in geodesy

The Impact of Social Media Signals on Supplier Selection: Insights from Two Experiments

Purpose: Online B2B markets offer buyers a new source of information provided by social media signals about suppliers. These signals have not yet received much attention in the supplier selection literature. This study advances our understanding of how buyers respond to social media signals in the supplier selection process. Design: We develop a choice-based conjoint experimental design to isolate and manipulate two signals from social media: volume (i.e. the number of ratings) and valence (i.e. average evaluation of the ratings). We test how these signals are interpreted in the context of varying deal sizes and price points. Findings: Both volume and valence are positively correlated with supplier selection. However, (i) the signals exhibit diminishing returns and (ii) the efficacy of valence is interpreted in the context of volume. We also find that (iii) there is no influence of the deal size and that (iv) the relationships between signals and supplier selection are negatively moderated by deviations from the reference price. Implications: Social media signals should be considered in supplier selection decisions as they convey valuable information to the buyer. However, signals go through a process of interpretation which has implications for buyers, suppliers, and owners of online B2B markets. Originality: Our research opens new lines of inquiry in behavioural operations management research regarding the mechanisms by which buyers interpret social media signals and how these ultimately influence their choice