Stability and change in embedded relationships: Broken ties in Japanese automotive keiretsu

This study examines how destabilizing pressures interact with embedded exchange relationships in an analysis of broken ties between Japanese auto manufacturers and their suppliers. While functional, political and social pressures all led to broken ties, their effect differed depending on the nature of the tie. We define two types of embeddedness, relational and normative, and argue that while political and social pressures lead to breakage of normatively embedded ties, relationally embedded ties are robust to these pressures. In contrast, functional pressures, specifically, performance, lead to breakage of relationally embedded ties. Our theory and empirical findings have implications for the study of networks and embeddedness and for research on institutional change in business systems

Strain Hardening in Polymer Glasses: Limitations of Network Models

Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While traditional entropic network models can be fit to the total stress, their underlying assumptions are inconsistent with simulation results. There is a substantial energetic contribution to the stress that rises rapidly as segments between entanglements are pulled taut. The thermal component of stress is less sensitive to entanglements, mostly irreversible, and directly related to the rate of local plastic arrangements. Entangled and unentangled chains show the same strain hardening when plotted against the microscopic chain orientation rather than the macroscopic strain.Comment: 4 pages, 3 figure

Decomposition, Condensation Defects, and Fusion

In this paper we outline the application of decomposition to condensation defects and their fusion rules. Briefly, a condensation defect is obtained by gauging a higher-form symmetry along a submanifold, and so there is a natural interplay with notions of decomposition, the statement that d-dimensional quantum field theories with global (Formula presented.) -form symmetries are equivalent to disjoint unions of other quantum field theories. We will also construct new (sometimes non-invertible) defects, and compute their fusion products, again utilizing decomposition. An important role will be played in all these analyses by theta angles for gauged higher-form symmetries, which can be used to select individual universes in a decomposition

Executive function in first-episode schizophrenia

BACKGROUND: We tested the hypothesis that schizophrenia is primarily a frontostriatal disorder by examining executive function in first-episode patients. Previous studies have shown either equal decrements in many cognitive domains or specific deficits in memory. Such studies have grouped test results or have used few executive measures, thus, possibly losing information. We, therefore, measured a range of executive ability with tests known to be sensitive to frontal lobe function. METHODS: Thirty first-episode schizophrenic patients and 30 normal volunteers, matched for age and NART IQ, were tested on computerized test of planning, spatial working memory and attentional set shifting from the Cambridge Automated Neuropsychological Test Battery. Computerized and traditional tests of memory were also administered for comparison. RESULTS: Patients were worse on all tests but the profile was non-uniform. A componential analysis indicated that the patients were characterized by a poor ability to think ahead and organize responses but an intact ability to switch attention and inhibit prepotent responses. Patients also demonstrated poor memory, especially for free recall of a story and associate learning of unrelated word pairs. CONCLUSIONS: In contradistinction to previous studies, schizophrenic patients do have profound executive impairments at the beginning of the illness. However, these concern planning and strategy use rather than attentional set shifting, which is generally unimpaired. Previous findings in more chronic patients, of severe attentional set shifting impairment, suggest that executive cognitive deficits are progressive during the course of schizophrenia. The finding of severe mnemonic impairment at first episode suggests that cognitive deficits are not restricted to one cognitive domain

Jamming under tension in polymer crazes

Molecular dynamics simulations are used to study a unique expanded jammed state. Tension transforms many glassy polymers from a dense glass to a network of fibrils and voids called a craze. Entanglements between polymers and interchain friction jam the system after a fixed increase in volume. As in dense jammed systems, the distribution of forces is exponential, but they are tensile rather than compressive. The broad distribution of forces has important implications for fibril breakdown and the ultimate strength of crazes.Comment: 4 pages, 4 figure

Poverty in the Aftermath of Katrina: Reimagining Citizen Leadership in t he Context of Federalism

It is a cruel irony that a lead singer with the name Katrina and a back-up band called the Waves performed a pop song in the 1980s with bright lyrics and happy beat. Many years later, a natural disaster bearing the same name, backed by a surge of seawater, consumed the city of New Orleans and the Gulf Coast. In the wake of Hurricane Katrina, America and the rest of the world witnessed the desperate side of the world\u27s wealthiest nation. Many people, who had neither time nor resources to escape the storm\u27s surge, and the destruction that followed, became first-hand witnesses to America\u27s failure to adequately address its poverty problem. The world was shocked to see Americans displaced and immobilized. Chilling reports of the disintegration of the community with rampant plundering and lawlessness punctuated media broadcasts. The ravages of death and deprivation were graphically depicted even as relief providers scrambled to address the massive needs of the displaced and injured. The failed infrastructure and lack of services to help the unfortunates who remained behind to weather the storm resurrected the national debate on poverty-who is responsible for giving willing Americans the tools to remove themselves from poverty to become contributing members of society