Uniaxial compression and creep behavior of a porous state change material

A reconfigurable tooling system (RTS) has been developed for use in manufacturing composite parts and molding liquid polymers. The RTS utilizes a state-change material that may also be useful as a water-soluble tooling material. The state-change material transitions from a liquid state to a solid state and then back to a liquid state. The material in its liquid state consists of glass microspheres in a solution of water-based binder and water. Through the application of heat and vacuum, the material can be hardened. When the material is in its solid state, the glass microspheres are glued together by small amounts of binder remaining in capillarity. Previous studies have been conducted to determine certain mechanical properties of the material in its hardened state. The focus of this study is to characterize variations of the state-change material in uniaxial compression at both ambient and elevated temperatures. Additionally, the room temperature uniaxial compression data is applied to a uniaxial compression creep study. The results show that material variation and test temperature significantly affect the compression and creep properties

Copy number variation in African Americans

<p>Abstract</p> <p>Background</p> <p>Copy number variants (CNVs) have been identified in several studies to be associated with complex diseases. It is important, therefore, to understand the distribution of CNVs within and among populations. This study is the first report of a CNV map in African Americans.</p> <p>Results</p> <p>Employing a SNP platform with greater than 500,000 SNPs, a first-generation CNV map of the African American genome was generated using DNA from 385 healthy African American individuals, and compared to a sample of 435 healthy White individuals. A total of 1362 CNVs were identified within African Americans, which included two CNV regions that were significantly different in frequency between African Americans and Whites (17q21 and 15q11). In addition, a duplication was identified in 74% of DNAs derived from cell lines that was not present in any of the whole blood derived DNAs.</p> <p>Conclusion</p> <p>The Affymetrix 500 K array provides reliable CNV mapping information. However, using cell lines as a source of DNA may introduce artifacts. The duplication identified in high frequency in Whites and low frequency in African Americans on chromosome 17q21 reflects haplotype specific frequency differences between ancestral groups. The generation of the CNV map will be a valuable tool for identifying disease associated CNVs in African Americans.</p

Addressing the food security and conservation challenges: Can be aligned instead of apposed?

This perspective article provides an overview of the interaction between food security and conservation as two of the most important challenges of our time. To provide a better understanding of the topic, a conceptual framework for the possible pathways of positive and negative impacts of protected areas (PAs) on four dimensions of food security is proposed. Considering the importance of hunting and shifting agriculture in food security and the challenges caused by them in conservation, the cases of hunting and shifting agriculture were explored. Finally, the rights-based approaches in conservation and food security, as a new approach with the potential to protect people and the planet as a synergistic approach is discussed

Spread of common native and invasive grasses and ruderal trees following anthropogenic disturbances in a tropical dry forest

Introduction A fundamental challenge to the integrity of tropical dry forest ecosystems is the invasion of non-native grass species. These grasses compete for resources and fuel anthropogenic wildfires. In 2012, a bulldozer from the Puerto Rico Electric Power Authority cleared a 570-m trail from a state road into a mature dry forest section of Guánica Forest to control a wildfire. We monitored colonization by a non-native invasive grass (Megathyrsus maximus), a highly invasive tree (Leucaena leucocephala), and a native grass (Uniola virgata), as well as natural regeneration, along the bulldozer trail. We determined whether bulldozing facilitated colonization by these species into the forest and the extent of spread. Results Distance from propagule source and temporal variations strongly influenced colonization by our three focal species. Megathyrsus maximus invaded along the trail from source populations by the state road. The establishment of new colonies of M. maximus seedlings went as far as 570 m inside the forest (i.e., at the end of the bulldozer trail), but we found most new colonies within 270 m of the road. Leucaena leucocephala exhibited a similar spreading pattern. Before disturbance, Uniola virgata was distributed widely across the forest, but the highest densities were found in areas near the latter portion (\u3e 401 m) of the bulldozer trail. Subsequently, the species formed new clumps along more than half of the trail (250 to 570 m), apparently colonizing from undisturbed patches nearby. Conclusions Bulldozing facilitated the invasion of non-native vegetation. The projected community assemblage will be more fire-prone than before since M. maximus carries fire across the landscape better than U. virgata, emphasizing the capacity of invasive plant colonization to alter local ecological processes after only a single wildfire and bulldoze event. Our results provide a valuable baseline for short-term vegetation response to anthropogenic disturbances in tropical semi-deciduous dry forests

Skunk River Review 2015-2016

https://openspace.dmacc.edu/skunkriver/1024/thumbnail.jp

A Quasi-Conforming Embedded Reproducing Kernel Particle Method for Heterogeneous Materials

We present a quasi-conforming embedded reproducing kernel particle method (QCE-RKPM) for modeling heterogeneous materials that makes use of techniques not available to mesh-based methods such as the finite element method (FEM) and avoids many of the drawbacks in current embedded and immersed formulations which are based on meshed methods. The different material domains are discretized independently thus avoiding time-consuming, conformal meshing. In this approach, the superposition of foreground (inclusion) and background (matrix) domain integration smoothing cells are corrected by a quasi-conforming quadtree subdivision on the background integration smoothing cells. Due to the non-conforming nature of the background integration smoothing cells near the material interfaces, a variationally consistent (VC) correction for domain integration is introduced to restore integration constraints and thus optimal convergence rates at a minor computational cost. Additional interface integration smoothing cells with area (volume) correction, while non-conforming, can be easily introduced to further enhance the accuracy and stability of the Galerkin solution using VC integration on non-conforming cells. To properly approximate the weak discontinuity across the material interface by a penalty-free Nitsche's method with enhanced coercivity, the interface nodes on the surface of the foreground discretization are also shared with the background discretization. As such, there are no tunable parameters, such as those involved in the penalty type method, to enforce interface compatibility in this approach. The advantage of this meshfree formulation is that it avoids many of the instabilities in mesh-based immersed and embedded methods. The effectiveness of QCE-RKPM is illustrated with several examples

Hematology, plasma biochemistry, and hormonal analysis of captive Louisiana pine snakes (Pituophis ruthveni): effects of intrinsic factors and analytical methodology

Blood analyte data are useful in health assessments and management of reptiles. There is a knowledge gap for blood analyte data of the endangered Louisiana pine snake (LPS; Pituophis ruthveni). The objectives of this study were to provide baseline hematology, plasma biochemical, and hormone data of captive LPS, to compare the data in juvenile and adult snakes and in adult snakes by sex, and to investigate methodological differences in hormone (serum vs. plasma) and protein analyses (total solids versus total protein). Blood samples from apparently healthy captive LPS were analyzed for hematology and plasma biochemistry (n = 11) and plasma and serum hormone analyses (n = 9). Packed cell volume (PCV) and absolute heterophils were significantly higher in adult compared with juvenile LPS, while PCV, white blood cell count, and absolute lymphocytes were higher in adult males compared with adult females. Significantly higher plasma concentrations were found in adults compared with juveniles for calcium, total protein, total solids, albumin, globulins, and bile acids. No significant differences were observed in 17β-estradiol measured in serum and plasma when comparing adults and juveniles and for 17β-estradiol in adult males and females. Plasma concentrations of 17β-estradiol were significantly lower than in serum. Serum testosterone in two adult males was 8.33 and 35.53 nmol/L, respectively, while it was undetectable in females and juveniles (n = 5). This study is the first to provide baseline information on blood analytes in endangered LPS, which will be useful for individual animals in managed care and as baseline for future population-level assessments

\u27Most men drink... especially like when they play sports\u27 - alcohol advertising during sporting broadcasts and the potential impact on child audiences

Alcohol advertising during sporting broadcasts, as well as the sponsorship of sporting events by the alcohol industry, is common practice in Australia, as in many other countries. The strength of the association between alcohol and sports prompts consideration of the potential for children who watch televised sport to be exposed to a considerable amount of alcohol advertising, and to learn to associate alcohol with sport and sporting success. This paper reviews the current alcohol advertising regulations in Australia, particularly in reference to the protection of children. It then details a pair of studies designed to examine the extent and nature of alcohol advertising during sporting telecasts, and the potential effects on young people. The first, a frequency and content analysis of advertising during two popular Australian sports final series, found that alcohol advertising (particularly during a sporting competition with alcohol company sponsors) is extensive and contains both features known to be appealing to children and messages which could be interpreted as associating alcohol consumption with social and sporting success. The second, a qualitative study with grade 5 and 6 primary school students, found that young people have a high awareness of the alcohol sponsors and alcohol brands advertised during these sporting telecasts, and associate these products with sport and with positive personal characteristics and outcomes