Location Choice, Product Choice, and the Human Resource Practices of Firms

This thesis is comprised of three chapters. The first investigates the implications of industrial clustering for labor mobility and earnings dynamics. Motivated by a theoretical model in which geographically clustered firms compete for workers, I exploit establishment-level variation in agglomeration to explore the impact of clustering in the software publishing industry on labor market outcomes. The results show that clustering makes it easier for workers to job hop among establishments within the sector. Further, workers in clusters have relatively steep earnings-tenure profiles, accepting lower wages early in their careers in exchange for stronger earnings growth and higher wages later. These findings underscore the importance of geography in understanding labor market dynamics within industries. While the first chapter reveals striking relationships between the human resource practices and location decisions of high-technology establishments, the second chapter (joint with F. Andersson, J. Haltiwanger, J. Lane, and K. Shaw) draws key connections between the hiring and compensation policies of innovative firms and the nature of their product markets. We show that software firms that operate in product markets with highly skewed returns to innovation pay a premium to attract talented workers. Yet these same firms also reward loyalty; that is, highly skilled workers faithful to their employers enjoy higher earnings in firms with a greater variance in potential payoffs from innovation. These results not only contribute to our knowledge of firm human resource practices and product market strategies, but also shed light on patterns of income inequality within and between industries. Building on this final idea, the last chapter (joint with F. Andersson, E. Davis, J. Lane, B. McCall, and L. Sandusky) examines the contribution of worker and firm reallocation to within-industry changes in earnings inequality. We find that the entry and exit of firms and the sorting of workers and firms based on worker skills are key determinants of changes in industry earnings distributions over time. However, the importance of these and other factors in driving observed dynamics in earnings inequality varies across sectors, with aggregate shifts often disguising fundamental differences in the underlying forces effecting change

Decomposing the Sources of Earnings Inequality: Assessing the Role of Reallocation

This paper exploits longitudinal employer-employee matched data from the U.S. Census Bureau to investigate the contribution of worker and firm reallocation to changes in earnings inequality within and across industries between 1992 and 2003. We find that factors that cannot be measured using standard cross-sectional data, including the entry and exit of firms and the sorting of workers across firms, are important sources of changes in earnings distributions over time. Our results also suggest that the dynamics driving changes in earnings inequality are heterogeneous across industries.inequality, linked employer-employee data, sorting

Decomposing the Sources of Earnings Inequality Assessing the Role of Reallocation

This paper uses matched employer-employee data from the Longitudinal Employer Household Dynamics database to investigate the contribution of worker and firm reallocation to within industry changes in wage inequality between 1992 and 2003. We find that the entry and exit of firms and the sorting of workers and firms based on underlying worker "skills" are important determinants of changes in industry earnings distributions over time. Our results suggest that the underlying dynamics of earnings inequality are complex and are due to factors that cannot be measured in standard crosssectional data.

Frenetic: A High-Level Language for OpenFlow Networks

Network administrators must configure network devices to simultaneously provide several interrelated services such as routing, load balancing, traffic monitoring, and access control. Unfortunately, most interfaces for programming networks are defined at the low level of abstraction supported by the underlying hardware, leading to complicated programs with subtle bugs. We present Frenetic, a high-level language for OpenFlow networks that enables writing programs in a declarative and compositional style, with a simple "program like you see every packet" abstraction. Building on ideas from functional programming, Frenetic offers a rich pattern algebra for classifying packets into traffic streams and a suite of operators for transforming streams. The run-time system efficiently manages the low-level details of (un)installing packet-processing rules in the switches. We describe the design of Frenetic, an implementation on top of OpenFlow, and experiments and example programs that validate our design choices.Office of Naval Research grant N00014-09-1-0770 "Networks Opposing Botnets

Non-Abelian statistics and topological quantum information processing in 1D wire networks

Topological quantum computation provides an elegant way around decoherence, as one encodes quantum information in a non-local fashion that the environment finds difficult to corrupt. Here we establish that one of the key operations---braiding of non-Abelian anyons---can be implemented in one-dimensional semiconductor wire networks. Previous work [Lutchyn et al., arXiv:1002.4033 and Oreg et al., arXiv:1003.1145] provided a recipe for driving semiconducting wires into a topological phase supporting long-sought particles known as Majorana fermions that can store topologically protected quantum information. Majorana fermions in this setting can be transported, created, and fused by applying locally tunable gates to the wire. More importantly, we show that networks of such wires allow braiding of Majorana fermions and that they exhibit non-Abelian statistics like vortices in a p+ip superconductor. We propose experimental setups that enable the Majorana fusion rules to be probed, along with networks that allow for efficient exchange of arbitrary numbers of Majorana fermions. This work paves a new path forward in topological quantum computation that benefits from physical transparency and experimental realism.Comment: 6 pages + 17 pages of Supp. Mat.; 10 figures. Supp. Mat. has doubled in size to establish results more rigorously; many other improvements as wel

Principles for the post-GWAS functional characterisation of risk loci

Several challenges lie ahead in assigning functionality to susceptibility SNPs. For example, most effect sizes are small relative to effects seen in monogenic diseases, with per allele odds ratios usually ranging from 1.15 to 1.3. It is unclear whether current molecular biology methods have enough resolution to differentiate such small effects. Our objective here is therefore to provide a set of recommendations to optimize the allocation of effort and resources in order maximize the chances of elucidating the functional contribution of specific loci to the disease phenotype. It has been estimated that 88% of currently identified disease-associated SNP are intronic or intergenic. Thus, in this paper we will focus our attention on the analysis of non-coding variants and outline a hierarchical approach for post-GWAS functional studies

Toward a Systematic Holographic QCD: A Braneless Approach

Recently a holographic model of hadrons motivated by AdS/CFT has been proposed to fit the low energy data of mesons. We point out that the infrared physics can be developed in a more systematic manner by exploiting backreaction of the nonperturbative condensates. We show that these condensates can naturally provide the IR cutoff corresponding to confinement, thus removing some of the ambiguities from the original formulation of the model. We also show how asymptotic freedom can be incorporated into the theory, and the substantial effect it has on the glueball spectrum and gluon condensate of the theory. A simple reinterpretation of the holographic scale results in a non-perturbative running for alpha_s which remains finite for all energies. We also find the leading effects of adding the higher condensate into the theory. The difficulties for such models to reproduce the proper Regge physics lead us to speculate about extensions of our model incorporating tachyon condensation.Comment: 27 pages, LaTe

A national survey of services for the prevention and management of falls in the UK

Background: The National Health Service (NHS) was tasked in 2001 with developing service provision to prevent falls in older people. We carried out a national survey to provide a description of health and social care funded UK fallers services, and to benchmark progress against current practice guidelines. Methods: Cascade approach to sampling, followed by telephone survey with senior member of the fall service. Characteristics of the service were assessed using an internationally agreed taxonomy. Reported service provision was compared against benchmarks set by the National Institute for Health and Clinical Excellence (NICE). Results: We identified 303 clinics across the UK. 231 (76%) were willing to participate. The majority of services were based in acute or community hospitals, with only a few in primary care or emergency departments. Access to services was, in the majority of cases, by health professional referral. Most services undertook a multi-factorial assessment. The content and quality of these assessments varied substantially. Services varied extensively in the way that interventions were delivered, and particular concern is raised about interventions for vision, home hazard modification, medication review and bone health. Conclusion: The most common type of service provision was a multi-factorial assessment and intervention. There were a wide range of service models, but for a substantial number of services, delivery appears to fall below recommended NICE guidance