Designing and Deploying Online Field Experiments

Online experiments are widely used to compare specific design alternatives, but they can also be used to produce generalizable knowledge and inform strategic decision making. Doing so often requires sophisticated experimental designs, iterative refinement, and careful logging and analysis. Few tools exist that support these needs. We thus introduce a language for online field experiments called PlanOut. PlanOut separates experimental design from application code, allowing the experimenter to concisely describe experimental designs, whether common "A/B tests" and factorial designs, or more complex designs involving conditional logic or multiple experimental units. These latter designs are often useful for understanding causal mechanisms involved in user behaviors. We demonstrate how experiments from the literature can be implemented in PlanOut, and describe two large field experiments conducted on Facebook with PlanOut. For common scenarios in which experiments are run iteratively and in parallel, we introduce a namespaced management system that encourages sound experimental practice.Comment: Proceedings of the 23rd international conference on World wide web, 283-29

Renormalization group flow of entanglement entropy on spheres

We explore entanglement entropy of a cap-like region for a generic quantum field theory residing in the Bunch-Davies vacuum on de Sitter space. Entanglement entropy in our setup is identical with the thermal entropy in the static patch of de Sitter, and we derive a simple relation between the vacuum expectation value of the energy-momentum tensor trace and the RG flow of entanglement entropy. In particular, renormalization of the cosmological constant and logarithmic divergence of the entanglement entropy are interrelated in our setup. We confirm our findings by recovering known universal contributions for a free field theory deformed by a mass operator as well as obtain correct universal behaviour at the fixed points. Simple examples of entanglement entropy flows are elaborated in $d=2,3,4$. In three dimensions we find that while the renormalized entanglement entropy is stationary at the fixed points, it is not monotonic. We provide a computational evidence that the universal `area law' for a conformally coupled scalar is different from the known result in the literature, and argue that this difference survives in the limit of flat space. Finally, we carry out the spectral decomposition of entanglement entropy flow and discuss its application to the F-theorem.Comment: 38 pages, 2 figures; v2: references added, version accepted to JHE

Density Dependence of the Mass Function of Globular Star Clusters in the Sombrero Galaxy and its Dynamical Implications

We have constructed the mass function of globular star clusters in the Sombrero galaxy in bins of different internal half-mass density rho_h and projected galactocentric distance R. This is based on the published measurements of the magnitudes and effective radii of the clusters by Spitler et al. (2006) in BVR images taken with the ACS on HST. We find that the peak of the mass function M_p increases with rho_h by a factor of about 4 but remains nearly constant with R. Our results are almost identical to those presented recently by McLaughlin & Fall (2007) for globular clusters in the Milky Way. The mass functions in both galaxies agree with a simple, approximate model in which the clusters form with a Schechter initial mass function and evolve subsequently by stellar escape driven by internal two-body relaxation. These findings therefore undermine recent claims that the present peak of the mass function of globular clusters must have been built into the initial conditions.Comment: Astrophysical Journal Letters, in press. 4 page

Nationwide Study of Breast Cancer Risk Factors in Latinas

Breast cancer is the most common cancer among American women. Any woman can be affected by breast cancer, with risk for the disease increasing with age. Risk for breast cancer is also exacerbated in women who have certain genetic alterations. Mutations in the BRCA1 and BRCA2 genes predispose women to breast and ovarian cancer, and are increasingly recognized in prostate and pancreatic cancers (1-3). In Caucasian and Asian ethnicities BRCA mutations are associated with basal-type/triple-negative disease. However this association between BRCA gene mutations and basal/triple-negative disease has been understudied in other ethnicities (4-6). The incidence and mortality of breast cancer of Hispanics and Native Americans are lower than other ethnicities; however they are underrepresented in epidemiological and clinical studies. Further, it is known that common recurrent mutations in BRCA1 and BRCA2 genes exist in Hispanic/Latino communities which account for 35-45% of mutation carriers (7, 8). The objective of our study is thus to investigate triple negative disease and BRCA gene mutations in Hispanic women

Nationwide Study of Breast Cancer Risk Factors in Latinas

Breast cancer is the most common cancer among American women. Any woman can be affected by breast cancer, with risk for the disease increasing with age. Risk for breast cancer is also exacerbated in women who have certain genetic alterations. Mutations in the BRCA1 and BRCA2 genes predispose women to breast and ovarian cancer, and are increasingly recognized in prostate and pancreatic cancers (1-3). In Caucasian and Asian ethnicities BRCA mutations are associated with basal-type/triple-negative disease. However this association between BRCA gene mutations and basal/triple-negative disease has been understudied in other ethnicities (4-6). The incidence and mortality of breast cancer of Hispanics and Native Americans are lower than other ethnicities; however they are underrepresented in epidemiological and clinical studies. Further, it is known that common recurrent mutations in BRCA1 and BRCA2 genes exist in Hispanic/Latino communities which account for 35-45% of mutation carriers (7, 8). The objective of our study is thus to investigate triple-negative disease and BRCA gene mutations in Hispanic women

Propaganda and documentary filmmaking

Thesis (M.S.V.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCHIncludes bibliographical references (leaves 25-26).This thesis consists of a text and a videotape, entitled A Call For Survival: Personal Responses to the Nuclear Threat. The written thesis is an analysis of documentary filmmaking as a form of discourse. Drawing on the work of Michel Foucault, a French historian and philosopher, the two basic approaches to documentary filmmaking are explored: the observational documentary and the propagandistic documentary. The techniques of each approach are evaluated in terms of their effects as mechanisms of power and knowledge. The two approaches are then examined in terms of how each has been incorporated into mass media. The videotape that accompanies this thesis is 3/4-inch U-Matic, 28 minutes long, color, sound, and in the English language.by Michael Roper.M.S.V.S