Rising Disability Payments: Are Cuts to Workers' Compensation Part of the Story?

There has been a large increase in the number of workers receiving Social Security Disability Insurance (DI) over the last quarter century. While most of this increase is explained by well-known demographic factors, such as the growing number of women in the workforce and the aging of the baby boomers, there is considerable concern that workers are increasingly choosing to collect DI benefits as an alternative to working. This concern has figured prominently in the debate over plans to maintain full funding for the DI program beyond the projected DI trust fund depletion date in late 2016.This paper examines the extent to which cuts in state workers' compensation (WC) benefits may have contributed to the rise in DI awards. To some extent, these programs may be seen as alternative sources of support for workers with job-related injuries. Insofar as injured workers are less able to receive WC benefits, they may be more likely to turn to the DI program. At the national level, there is a clear correlation between the sharp decline in WC benefits over the last quarter century and the rise in DI benefits. This paper examines whether there could be a causal relationship between the reduction in WC benefits and the rise in DI benefits by examining state-level data

Characterisation of novel Claudin gene expression during Petromyzon marinus embryo development

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2015.Claudins are a family of proteins that are conserved amongst all vertebrates, they are integral in the formation and maintenance of the tight junctions between epithelial cells. Claudins are implicated in embryo morphogenesis, vertebrate evolution, solute movement, cell-cell adhesion, designation of cellular and tissue identity, and several diseases when mutated. Petromyzon marinus (the sea lamprey) is the most basal extant vertebrate and is a model organism in both developmental and evolutionary biology for this reason. In this study, the expression patterns and functions of novel claudin genes in P. marinus were examined with the aim of discovering more about the role of claudins in vertebrate evolution. Presumptive claudin genes in P. marinus were compared to all known claudins in the NCBI database. Primers were designed against all known P. marinus claudin genes and RT-PCR was performed in order to determine their expression levels at embryonic stages E8 to E18, as well as in adult eye, gill, heart, liver and skin tissues. Probes were designed against Claudin 1a, Claudin 9, Claudin 10 and Claudin 19b and RNA in situ hybridisation was performed on embryos at developmental stages E4 to E31 in order to determine their spatial expression patterns. Areas of common claudin gene expression appear to include the pharyngeal arches, otic placode, neural tube, notochord and ectoderm. Claudin 1a is uniquely expressed in the lamprey migrating neural crest. Morpholino-mediated gene knockouts were performed on P. marinus embryos and the loss of Claudin 19b appears to result in abnormal somite morphogenesis

Foraging under conditions of short-term exploitative competition: The case of stock traders

Theory purports that animal foraging choices evolve to maximize returns, such as net energy intake. Empirical research in both human and nonhuman animals reveals that individuals often attend to the foraging choices of their competitors while making their own foraging choices. Due to the complications of gathering field data or constructing experiments, however, broad facts relating theoretically optimal and empirically realized foraging choices are only now emerging. Here, we analyze foraging choices of a cohort of professional day traders who must choose between trading the same stock multiple times in a row---patch exploitation---or switching to a different stock---patch exploration---with potentially higher returns. We measure the difference between a trader's resource intake and the competitors' expected intake within a short period of time---a difference we call short-term comparative returns. We find that traders' choices can be explained by foraging heuristics that maximize their daily short-term comparative returns. However, we find no one-best relationship between different trading choices and net income intake. This suggests that traders' choices can be short-term win oriented and, paradoxically, maybe maladaptive for absolute market returns

The empirical status of General Strain Theory: Racial differences in response to strain.

Agnew (1992) argued that interpersonal strain predisposes the individual toward corrective action, which may include involvement in delinquency/crime or drug use. He also states that it may be the case that different types of strain are relevant to different subgroups in this process (Agnew, 1992). This research examined this supposition where subgroups were defined by race. The results of this study are consistent with the view offered by strain theory (Agnew, 1992). General Strain Theory predicts that interpersonal strain will affect individual adaptations to the social environment (Agnew, 1992). The adaptation chosen is said to be conditioned by such variables as personal resources and emotional response. The current research examined these predictions when the data were disaggregated by race, and the findings tend to support the theory across groups. Interestingly, there were significant differences between groups on selected theoretical variables indicating that different types of strain and the role of the personal resources significantly differ in their association with negative affective states, delinquency/crime, and drug use for the groups

An Age, Size, and Climate Response Study of Old Growth Shortleaf Pine in the McCurtain County Wilderness Area, Oklahoma

Increment cores were extracted from 483 trees distributed over 21 semi-randomly sampled 0.1-hectare plots on three distinct landscape positions in the McCurtain County Wilderness Area (MCWA), a 57 square kilometer tract of uncut shortleaf pine in southeastern Oklahoma. Forty additional cores were taken off plot from older-appearing trees. All sampled trees were shortleaf pine (Pinus echinata) with a diameter at breast height (DBH) of at least 10 cm. Hardwoods were not included in the size and age analyses. The study site chosen for the sampling was made up of four parallel east-west trending ridges near North Linson Creek, making up about 1.3 square kilometers in area. The cores and diameter measurements were used to examine the age, size, basal area, density, and growth rate of the sampled pine stands. All core samples were dated dendrochronologically using the Douglass method of cross dating (Douglass, 1941) and measured for the development of earlywood (EW), latewood (LW), and total ring width (RW) chronologies. The average diameter for all randomly sampled trees at Linson Creek was 31.3 cm at breast height, and the average age was 100.3 years (i.e., the minimum age, based on core sampling at breast height). The size-age correlation was found to be stronger for the pines with a diameter of over 40 cm. A major pulse of shortleaf pine recruitment to breast height was detected from 1920-1940, when a sizable group of sampled trees reached ~1.4 m. Cumulative radial growth curves showed a wide variety of growth rates. When the effect of topographic position was tested, south-facing plots were found to have both the oldest and slowest-growing trees on average, and the youngest and smallest were found on the north-facing plots. Ridgetop plots had both the largest and fastest growing pines. The final chronology for Linson Creek dates from 1743 to 2020, and includes some individual trees cored outside of the randomly sampled plots due to their old appearance. These off-plot samples were not used for the dendroecological analyses, which were based only on the randomly sampled trees. Data from Stahle et al. (1985) were subsequently added to the Linson Creek samples to construct final, fully replicated chronologies of EW, LW, and RW, which extend from 1688 to 2020. The measured EW, LW, and RW chronologies were correlated with gridded instrumental Palmer Drought Severity Indices (PDSI) for the United States from 1895-2005. Results showed a significant positive correlation between latewood width and August PDSI in the same year as ring formation, not just in McCurtain County but also the surrounding states. Earlywood growth, by contrast, was only weakly correlated with June-July PDSI in the summer one year prior to EW formation

Development of Specifications for Modified Engineered Cementitious Composites (MECC) for use as Bridge Deck Overlays in Nevada

Engineered cementitious composite (ECC) material is a high-strength, fiber-reinforced, ductile mortar mixture that can exhibit tensile strains of up to 5%. The durability and mechanical properties of ECC make it a desirable construction material. This study presents an extensive evaluation of modified engineered cementitious composite (MECC) using locally sourced raw materials for use as a bridge-deck-overlay material. MECC is a mixture of cement, fly ash, water, concrete sand, and poly-vinyl alcohol fibers. The concrete sand used in this study was used in lieu of the typically used silica sand to reduce the high material cost, which makes MECC a modified ECC mix. Currently, the Nevada Department of Transportation (NDOT) uses a polymer concrete for bridge-deck-overlays in Nevada. While NDOT has had good performance with the polymer concrete overlays, the polymer concrete material is an expensive proprietary material. NDOT believes that MECC may be a viable alternative to the polymer concrete as a bridge-deck-overlay material.In this study, three different representative aggregates from throughout Nevada were selected to understand how the local aggregates would perform in MECC mixes. In total, eighteen different MECC mixes were evaluated using a total of thirteen different tests to determine the fresh and hardened properties of the MECC material. These tests included compressive strength, freeze-thaw durability, resistance to chloride ion penetration, and drying shrinkage. Additionally, a uniaxial tensile test was developed to test the tensile strengths and tensile strains of these different MECC mixes. In addition to evaluating MECC, samples of the polymer concrete and of a traditional Portland cement concrete mix were also tested. These results were used to determine how the performance of the MECC material compares with polymer concrete and traditional concrete. The laboratory test results were then analyzed using several different statistical analyses. First, all of the MECC mixes were compared with each other, and the polymer concrete and traditional concrete mixes. This showed how many mixes had statistically significantly higher/lower performance that both the polymer concrete and traditional concrete. Second, linear regressions were used to determine the standardized regression coefficients (or beta coefficients) which were used to determine which variables (mix proportions, aggregate source, fiber type) influenced the MECC’s properties. Third, additional MECC mixes were batched to determine which aggregate properties would influence the MECC’s properties. From this analysis, several predictive models were developed to predict the properties of an MECC mix that used a specific fine aggregate stockpile. After the completion of the laboratory phase, three different field trials were conducted to determine the feasibility of batching large amounts of MECC at commercial concrete batch plants. In these trials, approximately 6 cubic yards of MECC was mixed using different plant configurations to determine if any special measures would be needed to mix MECC on a large-scale. Additionally, a trial slab of MECC was placed at each of these field trials to determine how easy the MECC material would be to place, consolidate, and finish.The findings of this study are that MECC has many desirable qualities of a bridge-deck-overlay material. MECC has higher compressive strengths, higher tensile strengths and strains, high resistance to chloride ion penetration, and higher abrasion resistance than traditional concrete. Additionally, MECC has similar performance to the polymer concrete, meaning there is not a significant drop in performance between the materials. The large-scale trial batches showed that MECC could be mixed on a large-scale without any special measures. While MECC is harder to place than traditional concrete, it is not expected to require any specialty equipment for placement. The findings of this study were used to draft a specification for NDOT for the use of MECC as a bridge-deck-overlay material. This specification will be used in an upcoming field project by NDOT where a bridge-deck-overlay measuring approximately 28 feet by 140 feet by 4 inches thick will be placed in the spring of 2016 in Northern Nevada

An Age, Size, and Climate Response Study of Old Growth Shortleaf Pine in the McCurtain County Wilderness Area, Oklahoma

Increment cores were extracted from 483 trees distributed over 21 semi-randomly sampled 0.1-hectare plots on three distinct landscape positions in the McCurtain County Wilderness Area (MCWA), a 57 square kilometer tract of uncut shortleaf pine in southeastern Oklahoma. Forty additional cores were taken off plot from older-appearing trees. All sampled trees were shortleaf pine (Pinus echinata) with a diameter at breast height (DBH) of at least 10 cm. Hardwoods were not included in the size and age analyses. The study site chosen for the sampling was made up of four parallel east-west trending ridges near North Linson Creek, making up about 1.3 square kilometers in area. The cores and diameter measurements were used to examine the age, size, basal area, density, and growth rate of the sampled pine stands. All core samples were dated dendrochronologically using the Douglass method of cross dating (Douglass, 1941) and measured for the development of earlywood (EW), latewood (LW), and total ring width (RW) chronologies. The average diameter for all randomly sampled trees at Linson Creek was 31.3 cm at breast height, and the average age was 100.3 years (i.e., the minimum age, based on core sampling at breast height). The size-age correlation was found to be stronger for the pines with a diameter of over 40 cm. A major pulse of shortleaf pine recruitment to breast height was detected from 1920-1940, when a sizable group of sampled trees reached ~1.4 m. Cumulative radial growth curves showed a wide variety of growth rates. When the effect of topographic position was tested, south-facing plots were found to have both the oldest and slowest-growing trees on average, and the youngest and smallest were found on the north-facing plots. Ridgetop plots had both the largest and fastest growing pines. The final chronology for Linson Creek dates from 1743 to 2020, and includes some individual trees cored outside of the randomly sampled plots due to their old appearance. These off-plot samples were not used for the dendroecological analyses, which were based only on the randomly sampled trees. Data from Stahle et al. (1985) were subsequently added to the Linson Creek samples to construct final, fully replicated chronologies of EW, LW, and RW, which extend from 1688 to 2020. The measured EW, LW, and RW chronologies were correlated with gridded instrumental Palmer Drought Severity Indices (PDSI) for the United States from 1895-2005. Results showed a significant positive correlation between latewood width and August PDSI in the same year as ring formation, not just in McCurtain County but also the surrounding states. Earlywood growth, by contrast, was only weakly correlated with June-July PDSI in the summer one year prior to EW formation

Renewable Energy Electricity Generation in Arizona: What, Why, and Maybe How: Working Paper Series--02-35

Traditional fossil fuel production of electricity has serious externality issues that influence air quality, public health and viewscapes. In order to limit these influences, public policy aims at increasing the production of electricity using renewable fuels. For a variety of reasons, including market cost barriers, antiquated government policy and the overall lack of knowledge by energy consumers, renewable energy has had a tough time finding a niche in the energy marketplace in Arizona. In this paper we explain the problems with fossil fuel and nuclear energy sources, discuss the possibilities for renewable energy sources, digress on the theoretical question of treating air quality as a private externality or a public good, and propose various policy implements that will allow the state of Arizona to become a leader in the production of electricity from renewable sources