The Social Multiplier

In many cases, aggregate data is used to make inferences about individual level behavior. If there are social interactions in which one person’s actions influence his neighbor’s incentives or information, then these inferences are inappropriate. The presence of positive social interactions, or strategic complementarities, implies the existence of a social multiplier where aggregate relationships will overstate individual elasticities. We present a brief model and then estimate the size of the social multiplier in three areas: the impact of education on wages, the impact of demographics on crime and group membership among Dartmouth roommates. In all three areas there appears to be a significant social multiplier.

The Role of Risk Attitude in Preference Rankings of Vaccine Use for Foot and Mouth Disease Eradication in the U.S.

Food Security and Poverty,

IRAS 16293-2422: A very young binary system?

We present 4".5 x 2".5 resolution millimeter wavelength observations of the young far-infrared source IRAS 16293-2422 which resolve the continuum emission into two sources, MM 1 and MM 2. These sources coincide with known radio continuum sources and may constitute a very young binary system with a projected separation of 840 AU. Flux measurements from 18 cm to 25 μm show that the majority of the millimeter wavelength emission arises from dust within 300 AU of the individual central objects. The total dynamical mass of 1.1-1.3 M_⊙, coupled with our mass estimates for MM 1 and MM 2, suggests that the mass in circumstellar material is comparable to that of the central stellar cores. Since the stellar masses are constrained to be ≤ 0.5 M_⊙ each, it is likely that the bolometric luminosity of 30-40 L_⊙ is derived mainly from accretion of the observed circumstellar material. Maps of the J = 2, 3-1, 2 transition of SO obtained simultaneously show that this emission is centered on MM 1, with weaker emission in a clumpy distribution to the east and west. No SO emission is detected toward MM 2, indicating an upper limit to the fractional abundance which is a factor of 10 below that toward MM 1. We propose that the SO emission toward MM 1 is a result of the outflow activity associated with this source and that the outlying emission clumps trace regions of mild interaction between the outflow and the ambient cloud

The Social Multiplier

In many cases, aggregate data is used to make inferences about individual level behavior. If there are social interactions in which one person's actions influence his neighbor's incentives or information, then these inferences are inappropriate. The presence of positive social interactions, or strategic complementarities, implies the existence of a social multiplier where aggregate relationships will overstate individual elasticities. We present a brief model and then estimate the size of the social multiplier in three areas: the impact of education on wages, the impact of demographics on crime and group membership among Dartmouth roommates. In all three areas there appears to be a significant social multiplier.

Real-time simulation model of the HL-20 lifting body

A proposed manned spacecraft design, designated the HL-20, has been under investigation at Langley Research Center. Included in that investigation are flight control design and flying qualities studies utilizing a man-in-the-loop real-time simulator. This report documents the current real-time simulation model of the HL-20 lifting body vehicle, known as version 2.0, presently in use at NASA Langley Research Center. Included are data on vehicle aerodynamics, inertias, geometries, guidance and control laws, and cockpit displays and controllers. In addition, trim case and dynamic check case data is provided. The intent of this document is to provide the reader with sufficient information to develop and validate an equivalent simulation of the HL-20 for use in real-time or analytical studies

Linking Cellular and Mechanical Processes in Articular Cartilage Lesion Formation: A Mathematical Model

A severe application of stress on articular cartilage can initiate a cascade of biochemical reactions that can lead to the development of osteoarthritis. We constructed a multiscale mathematical model of the process with three components: cellular, chemical, and mechanical. The cellular component describes the different chondrocyte states according to the chemicals these cells release. The chemical component models the change in concentrations of those chemicals. The mechanical component contains a simulation of pressure application onto a cartilage explant and the resulting strains that initiate the biochemical processes. The model creates a framework for incorporating explicit mechanics, simulated by finite element analysis, into a theoretical biology framework

Goldstone-Mode Phonon Dynamics in the Pyrochlore Cd2Re2O7

We have measured the polarized Raman scattering spectra of Cd2Re2O7, the first superconducting pyrochlore, as a function of temperature. For temperatures below the cubic-to-tetragonal structural phase transition (SPT) at 200K, a peak with B1 symmetry develops at zero frequency with divergent intensity. We identify this peak as the first observation of the Goldstone phonon in a crystalline solid. The Goldstone phonon is a collective excitation that exists due to the breaking of the continuous symmetry with the SPT. Its emergence coincides with that of a Raman-active soft mode. The order parameter for both features derives from an unstable doubly-degenerate vibration (with Eu symmetry) of the O1 atoms which drives the SPT.Comment: 4+ pages, 4 figures. Updated figures and text. Accepted to PR

STUDIES ON THE LEUKOCYTOSIS AND LYMPHOCYTOSIS INDUCED BY BORDETELLA PERTUSSIS : III. THE DISTRIBUTION OF TRANSFUSED LYMPHOCYTES IN PERTUSSIS-TREATED AND NORMAL MICE

Peripheral blood lymphocytes were isolated from normal mice and mice undergoing pertussis-induced lymphocytosis. After labeling in vitro with tritiated uridine the cells were transfused into normal or pertussis-treated mice. It was found that the lymphocytes from pertussis-treated mice entered the lymph nodes of both normal mice and pertussis-treated mice to a significantly lesser extent than did normal lymphocytes which had been transfused into either class of recipient. In addition, an interdependence of changes in the various body compartments examined was found when normal lymphocytes were injected into either type of recipient. However, when pertussis lymphocytes were injected into normal mice there was no interrelationship between the changes in the node with those in the blood, liver, lung, or spleen. In the case of pertussis lymphocytes transfused into pertussis-treated mice no interrelationship between any two compartments was observed. It was concluded that in pertussis-treated mice there is an inhibition of lymphocyte emigration which is primarily the consequence of an effect on the cell

Supersymmetry, quark confinement and the harmonic oscillator

We study some quantum systems described by noncanonical commutation relations formally expressed as [q,p]=ihbar(I + chi H), where H is the associated (harmonic oscillator-like) Hamiltonian of the system, and chi is a Hermitian (constant) operator, i.e. [H,chi]=0 . In passing, we also consider a simple (chi=0 canonical) model, in the framework of a relativistic Klein-Gordon-like wave equation.Comment: To be published in Journal of Physics A: Mathematical and Theoretical (2007