Labor Unions and Voter Turnout in the American States: Direct Versus Indirect Mobilization

I examine the relationship between labor unions and voter turnout in the American states. Though it is well known that unions increase turnout directly, we know less about their indirect effects. Moreover, the indirect effects may consist of nonmember mobilization and aggregate strength. To examine the direct and indirect mechanisms, I analyze both state-level panel data and individual-level data with a multilevel approach. First, my panel analysis shows that unions are positively associated with turnout as expected. Yet, the association is observed only in midterm elections, but not in presidential elections. Second, more importantly, my individual-level analysis suggests that indirect nonmember mobilization and indirect aggregate strength are positively related to turnout, while direct member mobilization is not. The findings imply that the direct effects are limited and, thus, that decreasing levels of voter turnout due to recently declining union membership come primarily from indirect mobilization rather than direct mobilization.

Impact of Multiple Recycling on the Strength of Coarse Aggregate

Concrete structures are integral parts of modern civilization. Every year a huge amount of concrete waste is generated due to demolition of old concrete structures for replacing them with new high-rise buildings or other structures, which consequently, increasing the environmental loads. Recycling of demolished concrete is found to be an effective way for sustainable development which can also minimize the disposal problem associated with concrete waste. Recycling of demolished concrete to produce usable aggregate, therefore, has drawn attention of researchers in the field of concrete technology. However, most of the studies in this field are focused on 1st generation recycled aggregate. Effect of multiple recycling on the properties of aggregate is merely studied. In this study, the effect of multiple times recycling on aggregate strength is observed. Strength of aggregate is evaluated in laboratory by Aggregate Crushing Value (ACV) test and Aggregate Impact Value (AIV) test after each generation of recycling. The ACV and AIV values of 1st generation, 2nd generation and 3rd generation recycled aggregates are compared with the natural source aggregate. Strength degradation after each stage of recycling is recorded. In addition, the test results of 1st generation, 2nd generation and 3rd generation recycled aggregates are interpreted, investigated and compared with standard requirement to outline their corresponding applications. ACV value for natural aggregate is found to increase by 2.5% after 1st stage of recycling and it increased by 4.64% and 6.79% after 2nd and 3rd stage of recycling respectively. On the other hand, AIV value for natural aggregate is found to increase by 7.04% after 1st stage of recycling and it increased by 10.35% and 12.47% after 2nd and 3rd stage of recycling respectively. The study reveals that the strength of 1st generation recycled aggregates is quite similar to that of natural aggregate and can be used for concreting in general purposes. 2nd generation recycled aggregate cannot be used in the production of concrete in heavy duty floor but can successfully be used in concrete for wearing surface and 3rd generation recycled aggregates are too weak for road surfacing.

Experimental Evaluation of the Influence of Aggregate Strength on the Flexural Cracking Behavior of Epoxy Asphalt Mixtures

The flexural cracking resistance of an asphalt concrete mixture used in a steel bridge deck pavement needs to be higher than that of one used in ordinary pavement. In this study, mechanical experimental tests were used to evaluate the influence of the aggregate strength on the flexural cracking behavior of epoxy asphalt concrete (EAC). The aggregate fracture area of beam cross sections was quantitatively analyzed by digital image processing, and crack propagation in the mixture was analyzed using fracture mechanics theory. The bending test results showed that the EAC containing high-strength aggregates exhibited the highest flexural cracking resistance among all of the aggregate mixtures under the same conditions. The use of high-strength aggregates led to a reduction in the aggregate fracture area, thereby improving the flexural cracking resistance of the mixture. The aggregate strength had a significant influence on the flexural cracking propagation behavior of the mixture. Fatigue test results at strain-controlled levels of 600–1200 με and 15 °C showed that the aggregate strength had no evident influence on the fatigue properties of the EAC. It is recommended that high-strength aggregates are used to increase the fracture resistance of aggregates and the flexural crack resistance of EACs.

Soaking Effects on Strength Characteristics of Crushed Gravel and Limestone Unbound Aggregates

Strength characteristics of unbound aggregate materials critically affect base and sub-base thickness designs of construction working platforms and flexible pavements. Unsoaked California Bearing Ratio (CBR) is commonly used by state transportation agencies for quality control and design. However, depending on the amount of fines content (i.e., passing No. 200 sieve), the strength characteristics of unbound aggregate layers may severely be affected after soaking. This study investigates any correlations that may exist between soaked and unsoaked strengths of crushed gravel and limestone aggregates commonly used in the State of Illinois. A test matrix was established to consider the effects of varying fines content at 5% and 12%, plasticity index (PI) at 5% and 9%, and dust ratio (DR) at 0.4, 0.6, and 1.0 on aggregate strength. DR is the ratio of percent passing No. 200 sieve to percent passing No. 40 sieve. Most of the aggregate strength characterizations with 5% fines content were not sensitive to soaking in terms of CBR index. However, significant reductions in soaked and unsoaked CBR values were observed when fines content increased from 5% to 12%. The crushed limestone aggregate strengths were more affected by soaking than the crushed gravel aggregates. A prediction model was developed to predict soaked CBR values from unsoaked CBR tests considering material type, fines content, PI and DR.

Erythrocyte Aggregation and Blood Viscosity is Similar in Homozygous Sickle Cell Disease Patients with and without Leg Ulcers

Background There is no consensus regarding the role of red blood cell (RBC) aggregation in the pathogenesis of leg ulcers (LUs) in sickle cell disease (SCD). Objectives We sought to evaluate whether the cross-sectional determination of RBC aggregation and hematological indices were associated with the presence of LU in homozygous SCD. Methods Twenty-seven patients with LU and 23 with no history of ulceration were recruited into the study. A laser-assisted rotational red cell analyzer (LoRRca) was used in the determination of the aggregation index (AI), aggregation half-time (t 1/2), and the RBC aggregate strength (AMP). Hematological indices were determined using a CELL-DYN Ruby analyzer. Whole blood viscosity (WBV) and plasma viscosity (PV) were measured using a Vilastic bioprofiler. The data were presented as means ± standard deviation or median, interquartile range. Two-sample t-test was used to test for associations between the AIs, WBV, and PV in patients with and without LU. Statistical significance was taken as p < 0.05. All analyses were conducted using Stata/SE v. 12.1 (StataCorp, College Station, TX). Results The AI was comparable in the group with and without ulcers (68.6, 16.7 versus 67.7, 16.9; p = 0.74); t 1/2 (1.7, 1.3 versus 1.8, 1.3; p = 0.71); AMP (18.8, 14.5 versus 19.1, 13.3; p = 0.84), WBV (3.8, 1.2 versus 3.8, 0.7; p = 0.77); and the PV (1.3, 0.08 versus 1.4, 0.1; p = 0.31) and were also not statistically different between the groups of participants. Conclusion RBC aggregation and aggregate strength are not associated with leg ulceration in SCD.