Gravity Models of Trade: Unobserved Heterogeneity and Endogeneity

We consider the estimation of the usual Gravity model of trade, which involves flows of trade, say exports, from country i to country j in time period t. We suggest an easy-to-implement generalised method of moments estimator that avoids the issues associated with the usual fixed effects treatment of the unobserved heterogeneity in this type of models and at the same time provides consistent parameter estimates in the face of potentially endogenous covariates

A Bivariate Latent Class Correlated Generalized Ordered Probit Model with an Application to Modeling Observed Obesity Levels

Obesity is a major risk factor for several diseases including diabetes, heart disease and stroke. Increasing rates of obesity internationally are set to cost health systems increasing resources. In the US a conservative estimate puts resources already spent on obesity at $120 billion annually. Given scarce health care resources it is important that categorisation of the overweight and obese is accurate, such that health promotion and public health targeting can be as e§ective as possible. To test the accuracy of current categorisation within the overweight and obese we extend the discrete data latent class literature by explicitly deÖning a latent variable for class membership as a function of both observables and unobservables, thereby allowing the equations deÖning class membership and observed outcomes to be correlated. The procedure is then applied to modeling observed obesity outcomes, based upon an underlying ordered probit equation. We Önd the standard boundaries for converting

Multi-level mapping: Real-time dense monocular SLAM

We present a method for Simultaneous Localization and Mapping (SLAM) using a monocular camera that is capable of reconstructing dense 3D geometry online without the aid of a graphics processing unit (GPU). Our key contribution is a multi-resolution depth estimation and spatial smoothing process that exploits the correlation between low-texture image regions and simple planar structure to adaptively scale the complexity of the generated keyframe depthmaps to the texture of the input imagery. High-texture image regions are represented at higher resolutions to capture fine detail, while low-texture regions are represented at coarser resolutions for smooth surfaces. The computational savings enabled by this approach allow for significantly increased reconstruction density and quality when compared to the state-of-the-art. The increased depthmap density also improves tracking performance as more constraints can contribute to the pose estimation. A video of experimental results is available at http://groups.csail.mit.edu/rrg/multi_level_mapping.Charles Stark Draper Laboratory (Research Fellowship

The Sloan Digital Sky Survey Reverberation Mapping Project: Post-Starburst Signatures in Quasar Host Galaxies at z < 1

Quasar host galaxies are key for understanding the relation between galaxies and the supermassive black holes (SMBHs) at their centers. We present a study of 191 broad-line quasars and their host galaxies at z < 1, using high signal-to-noise ratio (SNR) spectra produced by the Sloan Digital Sky Survey Reverberation Mapping project. Clear detection of stellar absorption lines allows a reliable decomposition of the observed spectra into nuclear and host components, using spectral models of quasar and stellar radiations as well as emission lines from the interstellar medium. We estimate age, mass (M*), and velocity dispersion (sigma*) of the host stars, the star formation rate (SFR), quasar luminosity, and SMBH mass (Mbh), for each object. The quasars are preferentially hosted by massive galaxies with M* ~ 10^{11} Msun characterized by stellar ages around a billion years, which coincides with the transition phase of normal galaxies from the blue cloud to the red sequence. The host galaxies have relatively low SFRs and fall below the main sequence of star-forming galaxies at similar redshifts. These facts suggest that the hosts have experienced an episode of major star formation sometime in the past billion years, which was subsequently quenched or suppressed. The derived Mbh - sigma* and Mbh - M* relations agree with our past measurements and are consistent with no evolution from the local Universe. The present analysis demonstrates that reliable measurements of stellar properties of quasar host galaxies are possible with high-SNR fiber spectra, which will be acquired in large numbers with future powerful instruments such as the Subaru Prime Focus Spectrograph.Comment: ApJ in pres

A Bivariate Latent Class Correlated Generalized Ordered Probit Model with an Application to Modeling Observed Obesity Levels

Obesity is a major risk factor for several diseases including diabetes, heart disease and stroke. Increasing rates of obesity internationally are set to cost health systems increasing resources. In the US a conservative estimate puts resources already spent on obesity at $120 billion annually. Given scarce health care resources it is important that categorisation of the overweight and obese is accurate, such that health promotion and public health targeting can be as e§ective as possible. To test the accuracy of current categorisation within the overweight and obese we extend the discrete data latent class literature by explicitly deÖning a latent variable for class membership as a function of both observables and unobservables, thereby allowing the equations deÖning class membership and observed outcomes to be correlated. The procedure is then applied to modeling observed obesity outcomes, based upon an underlying ordered probit equation. We Önd the standard boundaries for converting

Gravity Models of Trade: Unobserved Heterogeneity and Endogeneity

We consider the estimation of the usual Gravity model of trade, which involves flows of trade, say exports, from country i to country j in time period t. We suggest an easy-to-implement generalised method of moments estimator that avoids the issues associated with the usual fixed effects treatment of the unobserved heterogeneity in this type of models and at the same time provides consistent parameter estimates in the face of potentially endogenous covariates

Air Traffic Management Technology Demonstration-1 Concept of Operations (ATD-1 ConOps), Version 2.0

This document is an update to the operations and procedures envisioned for NASA s Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1). The ATD-1 Concept of Operations (ConOps) integrates three NASA technologies to achieve high throughput, fuel-efficient arrival operations into busy terminal airspace. They are Traffic Management Advisor with Terminal Metering (TMA-TM) for precise time-based schedules to the runway and points within the terminal area, Controller-Managed Spacing (CMS) decision support tools for terminal controllers to better manage aircraft delay using speed control, and Flight deck Interval Management (FIM) avionics and flight crew procedures to conduct airborne spacing operations. The ATD-1 concept provides de-conflicted and efficient operations of multiple arrival streams of aircraft, passing through multiple merge points, from top-of-descent (TOD) to the Final Approach Fix. These arrival streams are Optimized Profile Descents (OPDs) from en route altitude to the runway, using primarily speed control to maintain separation and schedule. The ATD-1 project is currently addressing the challenges of integrating the three technologies, and their implantation into an operational environment. The ATD-1 goals include increasing the throughput of high-density airports, reducing controller workload, increasing efficiency of arrival operations and the frequency of trajectory-based operations, and promoting aircraft ADS-B equipage

Imprints of Short Distance Physics On Inflationary Cosmology

We analyze the impact of certain modifications to short distance physics on the inflationary perturbation spectrum. For the specific case of power-law inflation, we find distinctive -- and possibly observable -- effects on the spectrum of density perturbations.Comment: Revtex 4, 3 eps figs, 4 page

Therapeutic alliance in telephone-administered cognitive–behavioral therapy for hematopoietic stem cell transplant survivors.

A strong therapeutic alliance has been found to predict psychotherapeutic treatment success across a variety of therapeutic modalities and patient populations. However, only a few studies have examined therapeutic alliance as a predictor of psychotherapy outcome among cancer survivors, and none have examined this relation in telephone administered cognitive behavioral therapy (T-CBT). This study evaluated the extent to which therapeutic alliance affected psychotherapy outcomes in survivors of hematopoietic stem cell transplantation (HSCT), a treatment for some cancers