Studying and Modeling the Connection between People's Preferences and Content Sharing

People regularly share items using online social media. However, people's decisions around sharing---who shares what to whom and why---are not well understood. We present a user study involving 87 pairs of Facebook users to understand how people make their sharing decisions. We find that even when sharing to a specific individual, people's own preference for an item (individuation) dominates over the recipient's preferences (altruism). People's open-ended responses about how they share, however, indicate that they do try to personalize shares based on the recipient. To explain these contrasting results, we propose a novel process model of sharing that takes into account people's preferences and the salience of an item. We also present encouraging results for a sharing prediction model that incorporates both the senders' and the recipients' preferences. These results suggest improvements to both algorithms that support sharing in social media and to information diffusion models.Comment: CSCW 201

The power spectrum of galaxies in the 2dF 100k redshift survey

We compute the real-space power spectrum and the redshift-space distortions of galaxies in the 2dF 100k galaxy redshift survey using pseudo-Karhunen-Loeve eigenmodes and the stochastic bias formalism. Our results agree well with those published by the 2dFGRS team, and have the added advantage of producing easy-to-interpret uncorrelated minimum-variance measurements of the galaxy-galaxy, galaxy-velocity and velocity-velocity power spectra in 27 k-bands, with narrow and well-behaved window functions in the range 0.01h/Mpc < k < 0.8h/Mpc. We find no significant detection of baryonic wiggles, although our results are consistent with a standard flat Omega_Lambda=0.7 ``concordance'' model and previous tantalizing hints of baryonic oscillations. We measure the galaxy-matter correlation coefficient r > 0.4 and the redshift-distortion parameter beta=0.49+/-0.16 for r=1 (beta=0.47+/- 0.16 without finger-of-god compression). Since this is an apparent-magnitude limited sample, luminosity-dependent bias may cause a slight red-tilt in the power spectum. A battery of systematic error tests indicate that the survey is not only impressive in size, but also unusually clean, free of systematic errors at the level to which our tests are sensitive. Our measurements and window functions are available at http://www.hep.upenn.edu/~max/2df.html together with the survey mask, radial selection function and uniform subsample of the survey that we have constructed.Comment: Replaced to match accepted MNRAS version, with new radial/angular systematics plot and sigma8 typo corrected. High-res figures, power spectra, windows and our uniform galaxy subsample with mask at http://www.hep.upenn.edu/~max/2df.html or from [email protected]. 26 journal pages, 28 fig

Current cosmological constraints from a 10 parameter CMB analysis

We compute the constraints on a ``standard'' 10 parameter cold dark matter (CDM) model from the most recent CMB and data and other observations, exploring 30 million discrete models and two continuous parameters. Our parameters are the densities of CDM, baryons, neutrinos, vacuum energy and curvature, the reionization optical depth, and the normalization and tilt for both scalar and tensor fluctuations. Our strongest constraints are on spatial curvature, -0.24 < Omega_k < 0.38, and CDM density, h^2 Omega_cdm <0.3, both at 95%. Including SN 1a constraints gives a positive cosmological constant at high significance. We explore the robustness of our results to various assumptions. We find that three different data subsets give qualitatively consistent constraints. Some of the technical issues that have the largest impact are the inclusion of calibration errors, closed models, gravity waves, reionization, nucleosynthesis constraints and 10-dimensional likelihood interpolation.Comment: Replaced to match published ApJ version. More details added. 13 ApJ pages. CMB movies and color figs at http://www.hep.upenn.edu/~max/10par_frames.html or from [email protected]

Smoking and intention to quit in deprived areas of Glasgow: is it related to housing improvements and neighbourhood regeneration because of improved mental health?

Background: People living in areas of multiple deprivation are more likely to smoke and less likely to quit smoking. This study examines the effect on smoking and intention to quit smoking for those who have experienced housing improvements (HI) in deprived areas of Glasgow, UK, and investigates whether such effects can be explained by improved mental health. Methods: Quasi-experimental, 2-year longitudinal study, comparing residents’ smoking and intention to quit smoking for HI group (n=545) with non-HI group (n=517), adjusting for baseline (2006) sociodemographic factors and smoking status. SF-12 mental health scores were used to assess mental health, along with self-reported experience of, and General Practitioner (GP) consultations for, anxiety and depression in the last 12 months. Results: There was no relationship between smoking and HI, adjusting for baseline rates (OR=0.97, 95% CI 0.57 to 1.67, p=0.918). We found an association between intention to quit and HI, which remained significant after adjusting for sociodemographics and previous intention to quit (OR 2.16, 95% CI 1.12 to 4.16, p=0.022). We found no consistent evidence that this association was attenuated by improvement in our three mental health measures. Conclusions: Providing residents in disadvantaged areas with better housing may prompt them to consider quitting smoking. However, few people actually quit, indicating that residential improvements or changes to the physical environment may not be sufficient drivers of personal behavioural change. It would make sense to link health services to housing regeneration projects to support changes in health behaviours at a time when environmental change appears to make behavioural change more likely

Mixed tenure orthodoxy: practitioner reflections on policy effects

This article examines mixed tenure as a policy orthodoxy. It first sets out how mixed tenure may be considered to constitute an orthodoxy within planning, being generally accepted as a theory and practice even in the absence of supporting evidence. Five elements of this orthodoxy are identified, relating to (1) housing and the environment, (2) social change, (3) economic impacts, (4) sustainable communities, (5) and sociospatial integration. Interviews with practitioners involved with three social housing estates that have experienced mixed-tenure policy interventions are reported to consider why the implementation and effects of mixed tenure might not correspond with the orthodox understanding. It is argued that policy ambiguity and weaknesses in policy theory and specification, alongside practical constraints, lie behind incomplete and counterproductive policy implementation, but a belief in pursuing the policy orthodoxy persists nevertheless

Inhomogeneous reionization and the polarization of the cosmic microwave background

In a universe with inhomogeneous reionization, the ionized patches create a second order signal in the cosmic microwave background polarization anisotropy. This signal originates in the coupling of the free electron fluctuation to the quadruple moment of the temperature anisotropy. We examine the contribution from a simple inhomogeneous reionization model and find that the signal from such a process is below the detectable limits of the Planck Surveyor mission. However t he signal is above the fundamental uncertainty limit from cosmic variance, so th at a future detection with a high accuracy experiment on sub-arcminute scales is possible.Comment: 10 pages, 2 eps figures, final version accepted for publication in ApJ Letter

TEMPORAL PAYMENT ISSUES IN CONTINGENT VALUATION ANALYSIS

We analyze agent response to disparate payment schedules for protection of critical habitat units for the Seller sea lion in Alaska. The model allows for identification of implicit and explicit discount rates using information from a system of maximum likelihood equations. Testing is done using data for one, five, and fifteen year payment treatments.Research Methods/ Statistical Methods,