Maximum Coverage in the Data Stream Model: Parameterized and Generalized

We present algorithms for the Max-Cover and Max-Unique-Cover problems in the data stream model. The input to both problems are $m$ subsets of a universe of size $n$ and a value $k\in [m]$. In Max-Cover, the problem is to find a collection of at most $k$ sets such that the number of elements covered by at least one set is maximized. In Max-Unique-Cover, the problem is to find a collection of at most $k$ sets such that the number of elements covered by exactly one set is maximized. Our goal is to design single-pass algorithms that use space that is sublinear in the input size. Our main algorithmic results are: If the sets have size at most $d$, there exist single-pass algorithms using $\tilde{O}(d^{d+1} k^d)$ space that solve both problems exactly. This is optimal up to polylogarithmic factors for constant $d$. If each element appears in at most $r$ sets, we present single pass algorithms using $\tilde{O}(k^2 r/\epsilon^3)$ space that return a $1+\epsilon$ approximation in the case of Max-Cover. We also present a single-pass algorithm using slightly more memory, i.e., $\tilde{O}(k^3 r/\epsilon^{4})$ space, that $1+\epsilon$ approximates Max-Unique-Cover. In contrast to the above results, when $d$ and $r$ are arbitrary, any constant pass $1+\epsilon$ approximation algorithm for either problem requires $\Omega(\epsilon^{-2}m)$ space but a single pass $O(\epsilon^{-2}mk)$ space algorithm exists. In fact any constant-pass algorithm with an approximation better than $e/(e-1)$ and $e^{1-1/k}$ for Max-Cover and Max-Unique-Cover respectively requires $\Omega(m/k^2)$ space when $d$ and $r$ are unrestricted. En route, we also obtain an algorithm for a parameterized version of the streaming Set-Cover problem.Comment: Conference version to appear at ICDT 202

Experimental constraints on a dark matter origin for the DAMA annual modulation effect

A claim for evidence of dark matter interactions in the DAMA experiment has been recently reinforced. We employ a new type of germanium detector to conclusively rule out a standard isothermal galactic halo of Weakly Interacting Massive Particles (WIMPs) as the explanation for the annual modulation effect leading to the claim. Bounds are similarly imposed on a suggestion that dark pseudoscalars mightlead to the effect. We describe the sensitivity to light dark matter particles achievable with our device, in particular to Next-to-Minimal Supersymmetric Model candidates.Comment: v4: introduces recent results from arXiv:0807.3279 and arXiv:0807.2926. Sensitivity to pseudoscalars is revised in light of the first. Discussion on the subject adde

Sceptical Employees as CSR Ambassadors in Times of Financial Uncertainty

This chapter offers new insights into the understanding of internal (employee) perceptions of organizational corporate social responsibility (CSR) policies and strategies. This study explores the significance of employees’ involvement and scepticism upon CSR initiatives and focuses on the effects it may have upon word of mouth (WOM) and the development of employee–organisation relationships. Desk research introduces the research questions. Data for the research questions were gathered through a self-completion questionnaire distributed in a hardcopy form to the sample. An individual’s level of scepticism and involvement appears to affect the development of a positive effect on employees’ WOM. Involvement with the domain of the investment may be a central factor affecting relationship building within the organization, and upon generation of positive WOM. The chapter offers a conceptual framework to public relations (PR) and corporate communications practitioners, which may enrich their views and understanding of the use and value of CSR for communication strategies and practices. For-profit organisations are major institutions in today’s society. CSR is proffered as presenting advantages for (at macro level) society and (micro level) the organization and its employees. Concepts, such as involvement and scepticism, which have not been rigorously examined in PR and corporate communication literature, are addressed. By examining employee perceptions, managers and academic researchers gain insights into the acceptance, appreciation and effectiveness of CSR policies and activities upon the employee stakeholder group. This will affect current and future CSR communication strategies. The knowledge acquired from this chapter may be transferable outside the for-profit sector

Results from a Search for Light-Mass Dark Matter with a P-type Point Contact Germanium Detector

We report on several features present in the energy spectrum from an ultra low-noise germanium detector operated at 2,100 m.w.e. By implementing a new technique able to reject surface events, a number of cosmogenic peaks can be observed for the first time. We discuss several possible causes for an irreducible excess of bulk-like events below 3 keVee, including a dark matter candidate common to the DAMA/LIBRA annual modulation effect, the hint of a signal in CDMS, and phenomenological predictions. Improved constraints are placed on a cosmological origin for the DAMA/LIBRA effect.Comment: 4 pages, 4 figures. v2: submitted version. Minimal changes in wording, one reference adde

The association between human endogenous retroviruses and multiple sclerosis: a systematic review and meta-analysis

Background: The interaction between genetic and environmental factors is crucial to multiple sclerosis (MS) pathogenesis. Human Endogenous Retroviruses (HERVs) are endogenous viral elements of the human genome whose expression is associated with MS. Objective: To perform a systematic review and meta-analysis and to assess qualitative and quantitative evidence on the expression of HERV families in MS patients. Methods: Medline, Embase and the Cochrane Library were searched for published studies on the association of HERVs and MS. Meta-analysis was performed on the HERV-W family. Odds Ratio (OR) and 95% confidence interval (CI) were calculated for association. Results: 43 reports were extracted (25 related to HERV-W, 13 to HERV-H, 9 to HERV-K, 5 to HRES-1 and 1 to HER-15 family). The analysis showed an association between expression of all HERV families and MS. For HERV-W, adequate data was available for meta-analysis. Results from meta-analyses of HERV-W were OR = 22.66 (95%CI 6.32 to 81.20) from 4 studies investigating MSRV/HERV-W(MS-associated retrovirus) envelope mRNA in peripheral blood mononuclear cells, OR = 44.11 (95%CI 12.95 to 150.30) from 6 studies of MSRV/ HERV-W polymerase mRNA in serum/plasma and OR = 6.00 (95%CI 3.35 to 10.74) from 4 studies of MSRV/HERV-W polymerase mRNA in CSF

How does Brazil measure up? Comparing rankings through the lenses of nation brand indexes

A considerable amount of literature has been published on nation brand and yet not much regarding measurement. The purpose of this paper is to examine nation brand indexes and explore the unbalanced outcomes of a country’s position in these recognized instruments. Although research has been carried out on nation brand, no single study exists comparing a country in four diverse nation brand indexes, which are the reputable ones by Anholt (2007), Fetscherin (2010), Fombrun (2014) and Anholt and Govers (2014). This paper also reflects on the critical studies perspective of the place branding research domain, discussed by Lucarelli and Berg (2011). After a qualitative approach applied to Brazil, it is believed that these indexes mutually support and complement each other - even though they use different approaches, methodologies, samples, and data. Moreover, each of them has their own strengths and weaknesses in terms of accuracy and rationality. Findings from this paper’s evaluation may guide nation brand managers, governments, and researchers to recognize that indexes should be taken into account when analysing a nation brand and its complex image. Therefore, this paper contributes to existing knowledge on the critical studies perspective of the contemporary theoretical structure of the place branding research domain by providing a comparative study based on real data-based rankings of nation brand indexes

Reconceptualizing CSR in the media industry as relational accountability

In this paper, we reconceptualize CSR in the media industries by combining empirical data with theoretical perspectives emerging from the communication studies and business ethics literature. We develop a new conception of what corporate responsibility in media organizations may mean in real terms by bringing Bardoel and d’Haenens’ (European Journal of Communication 19 165–194 2004) discussion of the different dimensions of media accountability into conversation with the empirical results from three international focus group studies, conducted in France, the USA and South Africa. To enable a critical perspective on our findings, we perform a philosophical analysis of its implications for professional, public, market, and political accountability in the media, drawing on the insights of Paul Virilio. We come to the conclusion that though some serious challenges to media accountability exist, the battle for responsible media industries is not lost. In fact, the speed characterizing the contemporary media environment may hold some promise for fostering the kind of relational accountability that could underpin a new understanding of CSR in the media