Technology Transfer through Imports

While there is general agreement that technology differences must figure prominently in any successful account of the cross-country income variation, not much is known on the source of these technology differences. This paper examines cross-country income differences in terms of factor accumulation, domestic R&D, and foreign technological spillovers. The empirical analysis encompasses seventeen industrialized countries in four continents over three decades, at a level disaggregated enough to identify innovations in a number of key high-tech sectors. International technology transfer is found to play a crucial part in accounting for income differences. We also relate technology transfer to imports, showing that imports are often a major channel. At the same time, our analysis highlights that international technology transfer varies importantly across industries and countries.

An experimental documentation of pressure gradient and Reynolds number effects on compressible turbulent boundary layers

Attached supersonic turbulent boundary layers, with a wide range of adverse pressure gradient strengths, are investigated for Reynolds numbers from 11.7 x 1 million to 314 x 1 million. Surface pressure and surface shear measurements were obtained for six flow fields over the entire Reynolds number range. In addition, two flow fields - one with a moderate pressure gradient and the other with a severe pressure gradient - are thoroughly documented at a single Reynolds number. This experimental documentation includes both mean and fluctuating profiles throughout the flow field, and is sufficient to define the complete flow field, including the upstream undisturbed flow region

Freund-Rubin Revisited

We utilise the duality between M theory and Type IIA string theory to show the existence of Freund-Rubin compactifications of M theory on 7-manifolds with singularities supporting chiral fermions. This leads to a concrete way to study phenomenologically interesting quantum gravity vacua using a holographically dual three dimensional field theory.Comment: reference adde

Analysing International Trade Patterns: Comparative Advantage for the World’s Major Economies

Using disaggregate product data classified by the Harmonized System code, this paper computes the revealed comparative advantage (RCA) for seven major economies that, when combined, contributed more than 80% of global manufacturing exports in 1996-97 and 2006-07. Results show that in the last decade, Canada, the US, and Japan have lost their share of global exports, while China has increased its share three-fold. These losses occurred mainly for low-tech products for the US, but medium and high-tech (MHT) products for Canada and Japan. However, MHT products comprise the highest share of Japanese exports (70%) compared to Canada (which has the lowest share, approximately half of Japan’s). Canada is the only economy whose contribution to global MHT exports is lower than that of global total exports. Japan also has the highest share of RCA-based MHT exports of other East Asian countries (OEACs) and the US. China has the highest share of non-RCA- based MHT exports. Finally, the trade patterns for OEACs and Mexico did not change greatly in any dimension in the last decade. However, products with RCA have changed substantially in all economies, with the highest in Mexico

Dynamic Poisson Factorization

Models for recommender systems use latent factors to explain the preferences and behaviors of users with respect to a set of items (e.g., movies, books, academic papers). Typically, the latent factors are assumed to be static and, given these factors, the observed preferences and behaviors of users are assumed to be generated without order. These assumptions limit the explorative and predictive capabilities of such models, since users' interests and item popularity may evolve over time. To address this, we propose dPF, a dynamic matrix factorization model based on the recent Poisson factorization model for recommendations. dPF models the time evolving latent factors with a Kalman filter and the actions with Poisson distributions. We derive a scalable variational inference algorithm to infer the latent factors. Finally, we demonstrate dPF on 10 years of user click data from arXiv.org, one of the largest repository of scientific papers and a formidable source of information about the behavior of scientists. Empirically we show performance improvement over both static and, more recently proposed, dynamic recommendation models. We also provide a thorough exploration of the inferred posteriors over the latent variables.Comment: RecSys 201

Type IIA Orientifold Limit of M-Theory on Compact Joyce 8-Manifold of Spin(7)-Holonomy

We show that M-theory compactified on a compact Joyce 8-manifold of $Spin(7)$-holonomy, which yields an effective theory in $D = 3$ with $\N$ = 1 supersymmetry, admits at some special points in it moduli space a description in terms of type IIA theory on an orientifold of compact Joyce 7-manifold of $G_2$-holonomy. We find the evidence in favour of this duality by computing the massless spectra on both M-thory side and type IIA side. For the latter, we compute the massless spectra by going to the orbifold limit of the Joyce 7-manifold.Comment: 26 pages, 2 eps figures, Latex file, two references and one footnote added, corrected some typo

Kahler Independence of the G2-MSSM

The G2-MSSM is a model of particle physics coupled to moduli fields with interesting phenomenology both for colliders and astrophysical experiments. In this paper we consider a more general model - whose moduli Kahler potential is a completely arbitrary G2-holonomy Kahler potential and whose matter Kahler potential is also more general. We prove that the vacuum structure and spectrum of BSM particles is largely unchanged in this much more general class of theories. In particular, gaugino masses are still supressed relative to the gravitino mass and moduli masses. We also consider the effects of higher order corrections to the matter Kahler potential and find a connection between the nature of the LSP and flavor effects.Comment: Final version, matches the version published in JHE