Central station applications planning activities and supporting studies

The application of photovoltaic technology in central station (utility) power generation plants is considered. A program of data collection and analysis designed to provide additional information about the subset of the utility market that was identified as the initial target for photovoltaic penetration, the oil-dependent utilities (especially muncipals) of the U.S. Sunbelt, is described along with a series of interviews designed to ascertain utility industry opinions about the National Photovoltaic Program as it relates to central station applications

Assessing the Effects of Mergers and Acquisitions on Firm Performance, Plant Productivity, and Workers: New Evidence from Matched Employer-Employee Data

Studies of the effects of mergers and acquisitions focus on a single unit of analysis: firms, plants, or workers. In contrast, we model these events as transactions that simultaneously have cross-levels effects. Based on the theory of human capital, we generate a set of predictions regarding the antecedents and consequences of firm, plant, and worker turnover. Our empirical analysis is based on longitudinal, linked employer-employee data for virtually the entire population of Swedish manufacturing firms and employees for the period 1985-1998. These data allow us to assess the effects of mergers and acquisitions on firm performance, plant productivity, levels of employment, and compensation. Consistent with human capital theory, we find that mergers and acquisitions lead to improvements in firm performance and plant productivity, although they also result in the downsizing of establishments and firms. These transactions also appear to enhance the careers of workers because they provide a mechanism for improving the sorting and matching or workers and managers to firms and industries that best suit their skills.

Ownership Change, Productivity, and Human Capital: New Evidence from Matched Employer-Employee Data in Swedish Manufacturing

Empirical studies of the impact of changes in ownership of manufacturing plants on productivity (e.g., Lichtenberg and Siegel (1987, 1990a, 1990b), McGuckin and Nguyen (1995, 2001), and Maksimovic and Phillips (2001)) have provided limited evidence on how such transactions affect investment in human capital and have been based strictly on U.S. and U.K. data. We attempt to fill these gaps, based on an analysis of matched employer-employee data from over 19,000 Swedish manufacturing plants for the years 1985-1998. The sample covers virtually the entire population of manufacturing plants with 20 or more employees and a probability-based sample of smaller plants. We assess whether there are differential effects on productivity and human capital for different types of ownership changes, such as partial and full acquisitions and divestitures, and related and unrelated acquisitions. Our results suggest that ownership change results in an increase in relative productivity. We also find that plants involved in these transactions experience increases in average employee age, experience, and the percentage of employees with a college education. Ownership change also leads to an increase in wages and a reduction in the percentage of female workers. All of these patterns emerge most strongly for full acquisitions and divestitures and unrelated acquisitions.

Assessing the Effects of Ownership Change on Women and Minority Employees: Evidence from Matched Employer-Employee Data

While there have been numerous papers on the employment and wage effects of mergers and acquisitions, there has been no direct analysis of the impact of such ownership changes on minority and female workers. This is an unexplored "equity" dimension of these transactions. We fill this gap by analyzing linked employer-employee data for the entire population of Swedish workers and approximately 16,000 manufacturing plants for the period 1985-1998. For each worker employed in these establishments (as well as the entire population of workers), we have data on gender, age, national origin, level of education, type of education, location, industrial sector, annual earnings, as well as each employee's complete work history during the period. We also have data on numerous plant and firm-level characteristics, which allows us to control for additional factors that might result in changes in labor composition and relative compensation. Our findings suggest that ownership change does not significantly alter the relative earnings and employment status of minority and female workers.

Behavioural clusters and predictors of performance during recovery from stroke

We examined the patterns and variability of recovery post-stroke in multiple behavioral domains. A large cohort of first time stroke patients with heterogeneous lesions was studied prospectively and longitudinally at 1-2 weeks, 3 months and one year post-injury with structural MRI to measure lesion anatomy and in-depth neuropsychological assessment. Impairment was described at all timepoints by a few clusters of correlated deficits. The time course and magnitude of recovery was similar across domains, with change scores largely proportional to the initial deficit and most recovery occurring within the first three months. Damage to specific white matter tracts produced poorer recovery over several domains: attention and superior longitudinal fasciculus II/III, language and posterior arcuate fasciculus, motor and corticospinal tract. Finally, after accounting for the severity of the initial deficit, language and visual memory recovery/outcome was worse with lower education, while the occurrence of multiple deficits negatively impacted attention recovery

The effects of hemodynamic lag on functional connectivity and behavior after stroke

Stroke disrupts the brain's vascular supply, not only within but also outside areas of infarction. We investigated temporal delays (lag) in resting state functional magnetic resonance imaging signals in 130 stroke patients scanned two weeks, three months and 12 months post stroke onset. Thirty controls were scanned twice at an interval of three months. Hemodynamic lag was determined using cross-correlation with the global gray matter signal. Behavioral performance in multiple domains was assessed in all patients. Regional cerebral blood flow and carotid patency were assessed in subsets of the cohort using arterial spin labeling and carotid Doppler ultrasonography. Significant hemodynamic lag was observed in 30% of stroke patients sub-acutely. Approximately 10% of patients showed lag at one-year post-stroke. Hemodynamic lag corresponded to gross aberrancy in functional connectivity measures, performance deficits in multiple domains and local and global perfusion deficits. Correcting for lag partially normalized abnormalities in measured functional connectivity. Yet post-stroke FC-behavior relationships in the motor and attention systems persisted even after hemodynamic delays were corrected. Resting state fMRI can reliably identify areas of hemodynamic delay following stroke. Our data reveal that hemodynamic delay is common sub-acutely, alters functional connectivity, and may be of clinical importance

A Computational Procedure to Detect a New Type of High Dimensional Chaotic Saddle and its Application to the 3-D Hill's Problem

A computational procedure that allows the detection of a new type of high-dimensional chaotic saddle in Hamiltonian systems with three degrees of freedom is presented. The chaotic saddle is associated with a so-called normally hyperbolic invariant manifold (NHIM). The procedure allows to compute appropriate homoclinic orbits to the NHIM from which we can infer the existence a chaotic saddle. NHIMs control the phase space transport across an equilibrium point of saddle-centre-...-centre stability type, which is a fundamental mechanism for chemical reactions, capture and escape, scattering, and, more generally, ``transformation'' in many different areas of physics. Consequently, the presented methods and results are of broad interest. The procedure is illustrated for the spatial Hill's problem which is a well known model in celestial mechanics and which gained much interest e.g. in the study of the formation of binaries in the Kuiper belt.Comment: 12 pages, 6 figures, pdflatex, submitted to JPhys

Configurations of Handles and the Classification of Divergences in the String Partition Function

The divergences that arise in the regularized partition function for closed bosonic string theory in flat space lead to three types of perturbation series expansions, distinguished by their genus dependence. This classification of infinities can be traced to geometrical characteristics of the string worldsheet. Some categories of divergences may be eliminated in string theories formulated on compact manifolds.Comment: 24 pages, DAMTP-R/94/1