Plant-level Productivity and Imputation of Missing Data in U.S. Census Manufacturing Data

Within-industry differences in measured plant-level productivity are large. A large literature has been devoted to explaining the causes and consequences of these differences. In the U.S. Census Bureau's manufacturing data, the Bureau imputes for missing values using methods known to result in underestimation of variability and potential bias in multivariate inferences. We present an alternative strategy for handling the missing data based on multiple imputation via sequences of classification and regression trees. We use our imputations and the Bureau's imputations to estimate within-industry productivity dispersions. The results suggest that there is more within-industry productivity dispersion than previous research has indicated. We also estimate relationships between productivity and market structure and between output prices, capital, and the probability of plant exit (controlling for productivity) based on the improved imputations. For some estimands, we find substantially different results than those based on the Census Bureau's imputations.

Before-Commit Client State Management Services for AJAX Applications

Heavily script-based browser applications change the manner in which users interact with Web browsers. Instead of downloading a succession of HTML pages, users download a single application and use that application for a long period of time. The application is not a set of HTML pages, but rather a single page that can possible modify its own presentation based on data exchanged with a server. In such an environment, it is necessary to provide some means for the client to manage its own state. We describe the initial results of our work in providing client-side state management services for these script-based applications. We focus on browser-based services that can help the user before any data is committed on the server. Our services include state checkpointing, property binding, operation logging, operational replay, ATOM/RSS data updates, and application-controlled persistence

A New Reality for US-China Trade? (with transcript)

In this episode of the Case in Point podcasts, Penn Law’s William Burke-White and Bloomberg Law’s Jerome Ashton discuss President-Elect Trump, trade, and the future of the Trans-Pacific Partnership (TPP). Produced by Penn Law in collaboration with Bloomberg Law

Unscreened Coulomb repulsion in the one dimensional electron gas

A tight binding model of electrons interacting via bare Coulomb repulsion is numerically investigated by use of the Density Matrix Renormalization Group method which we prove applicable also to very long range potentials. From the analysis of the elementary excitations, of the spin and charge correlation functions and of the momentum distribution, a picture consistent with the formation of a one dimensional "Wigner crystal" emerges, in quantitative agreement with a previous bosonization study. At finite doping, Umklapp scattering is shown to be ineffective in the presence of long range forces.Comment: RevTex, 5 pages with 8 eps figures. To be published on Phys. Rev.

The effect of estradiol on the fatty acid metabolism of the rat

Female Sprague-Dawley rats (220-240 g) were ovariectomized and seven days later were either treated as controls or received a single injection of either 0.1 μg, 100 μg, or 2 mg of estradiol-17β dissolved in 0.1 cc propylene glycol. These rats were autopsied either 1, 3, 6, 24, 48, or 72 hours after injection. Some of the ovariectomized animals were also hypophysectomized on either the fifth or sixth day after castration. Of these, some were injected with a single dose of either 2 mg estradiol, or 10 or 20 IU of ACTH. Plasma samples of all of the treatments included in this study were analyzed by gas-liquid chromatography for the percent composition of fatty acids present. The percent composition of fatty acids present in adipose tissue for some control and 100 μg and 2 mg ovariectomized estradiol treated animals are included. Identification of fatty acids was based on relative retention times and separation by thin layer chromatography. Free fatty acid levels were determined for ovariectomized animals which received 2 mg estradiol. Both whole body and dorso-lumbar fat pad weights were recorded. It was determined that estradiol at all levels tested brings about a change in the composition of the plasma fatty acids 24 hours after injection. As dosage increased the change becomes more pronounced. At the lowest dose (0.1 μg) only slight changes appear at 24 hours after injection. With 100 μg the fatty acid composition starts to change by 12 hours after injection, is complete by 24 hours and then returns to the control levels by 72 hours. With 2 mg the fatty acid composition remains altered for the duration of time (72 hours) studied. The changes in fatty acid levels at 24 hours after injection of 2 mg estradiol are as follows: palmitic acid changes from 16.61 ± 0.56% in the non-injected controls to 23.69 ± 0.74% in the treated animals, stearic acid changes from 16.44 ± 0.43% to 12.81 ± 0.54%, oleic acid changes from 13.66 ± 0.39% to 20.58 ± 0.76%, linoleic acid changes from 19.48 ± 0.51% to 26.01 ± 0.56% and arachidonic acid changes from 33.30 ± 0.92% to 16.91 ± 1.08%. No change was noted in the fatty acid composition of adipose tissue, nor were the dorso-lumbar fat pad weights affected by estradiol treatment. Plasma free fatty acids showed no significant changes. A slight decrease was observed in the body weights of those animals treated with 2 mg estradiol. Plasma fatty acid composition in hypophysectomized plus estradiol or ACTH treated animals was similar to that of ovariectomized estradiol treated animals. Mechanisms are presented for the altered plasma fatty acid compositions brought about by estradiol and hypophysectomy treatment. Their significance is discussed