Highly Magnified Stars in Lensing Clusters: New Evidence in a Galaxy Lensed by MACS J0416.1-2403

We examine a caustic-straddling arc at $z=0.9397$ in the field of the galaxy cluster MACS J0416.1-2403 ($z=0.397$) using archival multiband HST images and show that its surface brightness exhibits anomalies that can be explained by a single highly magnified star undergoing microlensing. First, we show that the surface brightness pattern is not perfectly symmetric across the cluster critical curve, which is inconsistent with a locally smooth lens model; the location of the candidate star exhibits the most significant asymmetry. Second, our analysis indicates that the asymmetric feature has $\sim 30\%$ higher flux in the 2012 visits compared to the Frontier Fields program visits in 2014. Moreover, the variable asymmetric feature shows an anomalous color between the F814W and F105W filters in 2014. These anomalies are naturally explained by microlensing induced variability of a caustic-transiting blue supergiant in a star-forming region, with a mean magnification factor around $\mu \sim 200$. We extend this study to a statistical analysis of the whole arc image and find tentative evidence of the increased mismatch of the two images in the proximity of the critical line. Robust detection of one or multiple caustic-transiting stars in this arc will enable detailed follow-up studies that can shed light on the small-scale structure of the dark matter inside the cluster halo.Comment: 12 pages, 10 figures, submitted to Ap

Evidence of amplitude modulation due to Resonant Mode Coupling in the delta Scuti star KIC5892969

A study of the star KIC5892969 observed by the Kepler satellite is presented. Its three highest amplitude modes present a strong amplitude modulation. The aim of this work is to investigate amplitude variations in this star and their possible cause. Using the 4 years-long observations available, we obtained the frequency content of the full light curve. Then, we studied the amplitude and phase variations with time using shorter time stamps. The results obtained are compared with the predicted ones for resonant mode coupling of an unstable mode with lower frequency stable modes. Our conclusion is that resonant mode coupling is consistent as an amplitude limitation mechanism in several modes of KIC5892969 and we discuss to which extent it might play an important role for other delta Scuti stars

Persuading Consumers With Social Attitudes

This paper analyzes persuasive advertising and pricing in oligopoly if firms sell differentiated products and consumers have heterogenous social attitudes towards the consumption by others. Deriving product demand from primitives, we show that the demand-enhancing effect of persuasive advertising varies across consumers and increases in the average degree of conformity. In equilibrium, both quality and cost leaders choose higher advertising intensities and charge higher prices than their competitors. In addition, we show that an increase in the average degree of conformity among consumers reinforces asymmetries between firms.Advertising, social attitude, consumption externality, quality

Uptake of inter-organizational IT systems in two Australian agricultural cooperatives: a match between business relationships and design features

In this paper we will advance a perspective that links business network analysis to interorganizational IT systems(IOS) uptake, starting with an analytic framework to characterize both different types of electronic business to business interactions (via the web) as well as the network of business relationships in which they are used. In order to see whether inter-organizational IT systems and business networks (mis)match they are compared on two dimensions: 'mode of interaction' (relational versus transactional) and 'nature of coordination' (emergent versus directive). The study analyses two Australian agricultural cooperatives 'Capgrains' and 'Bluegum'. The transactional focus and directive control of Capgrains' online ordering system did not match with the relational interaction and emergent coordination that was common in their network of business relationships, resulting in a mismatch and low level of use of the system. The Bluegum's group communication system much better matched with the business relationships in the cooperative and higher use of the IOS. Indicating a positive relation betweenmatch and uptake of the IOS