An investigation of the strength of aluminum wire used in integrated circuits

Microloop pull test is developed to stress wire loops in situ until failure. The applied loads, the nature of the fracture, and its location are recorded. This test also stresses the wire bonds

Mechanical switching of ferro-electric rubber

At the A to C transition, smectic elastomers have recently been observed to undergo $\sim$35% spontaneous shear strains. We first explicitly describe how strains of up to twice this value could be mechanically or electrically induced in Sm-$C$ elastomers by rotation of the director on a cone around the layer normal at various elastic costs depending on constraints. Secondly, for typical sample geometries, we give the various microstructures in Sm-$C$ akin to those seen in nematic elastomers under distortions with constraints. It is possible to give explicit results for the nature of the textures. Chiral Sm-$C$ elastomers are ferro-electric. We calculate how the polarization could be mechanically reversed by large, hard or soft strains of the rubber, depending upon sample geometry.Comment: 15 pages, 12 figure

SOME IMPLICATIONS OF LABOR ADJUSTMENTS IN A DUAL ECONOMY FRAMEWORK: WYOMING'S ENERGY-AGRICULTURE INTERFACE

Labor and Human Capital,

Distributions of Long-Lived Radioactive Nuclei Provided by Star Forming Environments

Radioactive nuclei play an important role in planetary evolution by providing an internal heat source, which affects planetary structure and helps facilitate plate tectonics. A minimum level of nuclear activity is thought to be necessary --- but not sufficient --- for planets to be habitable. Extending previous work that focused on short-lived nuclei, this paper considers the delivery of long-lived radioactive nuclei to circumstellar disks in star forming regions. Although the long-lived nuclear species are always present, their abundances can be enhanced through multiple mechanisms. Most stars form in embedded cluster environments, so that disks can be enriched directly by intercepting ejecta from supernovae within the birth clusters. In addition, molecular clouds often provide multiple episodes of star formation, so that nuclear abundances can accumulate within the cloud; subsequent generations of stars can thus receive elevated levels of radioactive nuclei through this distributed enrichment scenario. This paper calculates the distribution of additional enrichment for $^{40}$K, the most abundant of the long-lived radioactive nuclei. We find that distributed enrichment is more effective than direct enrichment. For the latter mechanism, ideal conditions lead to about 1 in 200 solar systems being directly enriched in $^{40}$K at the level inferred for the early solar nebula (thereby doubling the abundance). For distributed enrichment from adjacent clusters, about 1 in 80 solar systems are enriched at the same level. Distributed enrichment over the entire molecular cloud is more uncertain, but can be even more effective.Comment: 24 pages, 8 figures, accepted for publication in Ap

Transient shear banding in the nematic dumbbell model of liquid crystalline polymers

In the shear flow of liquid crystalline polymers (LCPs) the nematic director orientation can align with the flow direction for some materials, but continuously tumble in others. The nematic dumbbell (ND) model was originally developed to describe the rheology of flow-aligning semi-flexible LCPs, and flow-aligning LCPs are the focus in this paper. In the shear flow of monodomain LCPs it is usually assumed that the spatial distribution of the velocity is uniform. This is in contrast to polymer solutions, where highly non-uniform spatial velocity profiles have been observed in experiments. We analyse the ND model, with an additional gradient term in the constitutive model, using a linear stability analysis. We investigate the separate cases of constant applied shear stress, and constant applied shear rate. We find that the ND model has a transient flow instability to the formation of a spatially inhomogeneous flow velocity for certain starting orientations of the director. We calculate the spatially resolved flow profile in both constant applied stress and constant applied shear rate in start up from rest, using a model with one spatial dimension to illustrate the flow behaviour of the fluid. For low shear rates flow reversal can be seen as the director realigns with the flow direction, whereas for high shear rates the director reorientation occurs simultaneously across the gap. Experimentally, this inhomogeneous flow is predicted to be observed in flow reversal experiments in LCPs.Comment: 16 pages, 15 figure

The Economic impact of Florida's recreational boating industry in 1985

The recreational boating industry is an important component of Florida's economy. Previous Florida Sea Grant College supported research has documented this economic importance to the state's economy in 1980 (see Milon and Riddle, 1983, and Milon et al. 1983). Since that initial research, the manufacturing, retailing, and service sectors comprising the industry have continued to grow and prosper as the state's resident and tourist populations increased. This report is an update on the economic significance of the recreational boating industry in Florida since 1980 based on economic indicators of change within the industry. (21pp.

A non-monotonic constitutive model is not necessary to obtain shear banding phenomena in entangled polymer solutions

In 1975 Doi and Edwards predicted that entangled polymer melts and solutions can have a constitutive instability, signified by a decreasing stress for shear rates greater than the inverse of the reptation time. Experiments did not support this, and more sophisticated theories incorporated Marrucci's idea (1996) of removing constraints by advection; this produced a monotonically increasing stress and thus stable constitutive behavior. Recent experiments have suggested that entangled polymer solutions may possess a constitutive instability after all, and have led some workers to question the validity of existing constitutive models. In this Letter we use a simple modern constitutive model for entangled polymers, the non-stretching Rolie-Poly model with an added solvent viscosity, and show that (1) instability and shear banding is captured within this simple class of models; (2) shear banding phenomena is observable for weakly stable fluids in flow geometries that impose a sufficiently inhomogeneous total shear stress; (3) transient phenomena can possess inhomogeneities that resemble shear banding, even for weakly stable fluids. Many of these results are model-independent.Comment: 5 figure

Relationships between Time Management, Control, Work–family Conflict, and Strain

This article incorporates recent research regarding time management into a model of work–family conflict. The authors hypothesized that 3 types of time management behavior would have both direct and indirect (through perceived control of time) relationships, with work interfering with family and family interfering with work. It was also hypothesized that both of these types of work-family conflict would be related to the strain outcomes of job dissatisfaction and health complaints. This model was tested with a sample of 522 workers. In general, the hypothesized relationships were supported