Experimental Sand-Asphalt Surface

Wearing surfaces of Kentucky rock asphalt applied in thin layers were used extensively in Kentucky for many years. Sand asphalts, which generically include rock asphalt, are now a reemergent generation of surfacings to be investigated (1,2,3). An interim report (4) related the construction and interim performance of trial surfacings in Logan County. Two bridge deck sand-asphalt surfacings have been reported (5). This report covers sand-asphalt construction and performance since 1966. Pertinent project data and comments are contained in Appendix A. The several Special Provisions are included in Appendix B. Interest in sand-asphalt wearing surfaces issues from the skid-resistant qualities which are inherent in angular (unpolished) quartz sands. Blends of quartz sands together with crushed limestone sands have been employed experimentally to obtain strength and durability--and to evaluate the effect of limestone or carbonate sands on skid-resistance. Quartz concentrations in the order of 50 percent of the combined sand have not provided the desired assurances of persistent skid resistance; therefore, recourse to mixtures richer in quartz has become imperative. Experimental work is continuing in that direction

Slurry Seal Maintenance Applications

A slurry seal mixture consists of graded fine aggregate (normally minus 3/8-inch material), mixing grade emulsified asphalt (SS-1 or SS-lH), and water. The water is added to aid in mixing and to provide a free-flowing consistency so that the mixture can be spread in thin layers on the surface of an existing pavement. After the mixture is spread, the water evaporates and the remaining material, aggregate and base asphalt, forms a thin seal on the pavement surface which resembles a fine-grained asphaltic-concrete surface. As a result of the free-flowing consistency and the fineness of the aggregate, a slurry mixture readily fills cracks, voids, small depressions, and will form a thin seal over the entire pavement surface

Potential profitability of pearl culture in coastal communities in Tanzania

Artisanal half-pearl culture has been shown to provide livelihood and economic opportunities for coastal communities in Tanzania that depend directly on exploitation of marine resources. However, these pilot research studies have been supported by donor organisations and the economic feasibility of such development has not yet been assessed. Furthermore, there is little understanding of the costs required to establish pearl farms and the relative impacts of farm size on production, running costs, profitability and risks involved in production. The aim of this study was to develop economic models for subsistence level half-pearl culture in Tanzania. Models were generated for various scenarios relating to farm size and products (i.e. half-pearls and juvenile oyster or ‘spat’ collection) and they give detail on infrastructure costs, operational costs and income generated for various levels of operation. We concluded that the most profitable model for community-based pearl farming is to culture at least 600 oysters for half-pearl production. However, for communities to be able to run a sustainable and profitable enterprise, development of a sustainable source of oysters is crucial. Farmers can also generate income from collection of juvenile oysters and their subsequent sale to pearl farmers, but this is less profitable than half-pearl farming and requires a longer operational period before profits are made. Like pearl farming, there were major benefits or economies of scale with the largest farms tested providing greatest profit and/or a shorter time required to reach profitability. Our results provide a valuable source of information for prospective pearl farmers, donors, funding bodies and other stakeholders, and valuable extension information supporting further development of pearl culture in Tanzania

Comparison of Contained Rock Asphalt Mat (CRAM) with Conventional Asphaltic Concrete Pavements

A brochure proposing the use of Contained Rock Asphalt Mat (CRAM) provided a comparison of stress distributions throughout a CRAM structure (Figure 1) as compared to a conventional pavement (Figure 2). Experience has indicated that stress distributions do not always present the most sensitive or appropriate analysis of a pavement structure. Distributions of strains, and more particularly work , are better indicators of load distributions throughout a pavement structure and subsequent performance

Rat Urinary Bladder Carcinogenesis by Dual-Acting PPARα + γ Agonists

Despite clinical promise, dual-acting activators of PPARα and γ (here termed PPARα+γ agonists) have experienced high attrition rates in preclinical and early clinical development, due to toxicity. In some cases, discontinuation was due to carcinogenic effect in the rat urothelium, the epithelial layer lining the urinary bladder, ureters, and kidney pelvis. Chronic pharmacological activation of PPARα is invariably associated with cancer in rats and mice. Chronic pharmacological activation of PPARγ can in some cases also cause cancer in rats and mice. Urothelial cells coexpress PPARα as well as PPARγ, making it plausible that the urothelial carcinogenicity of PPARα+γ agonists may be caused by receptor-mediated effects (exaggerated pharmacology). Based on previously published mode of action data for the PPARα+γ agonist ragaglitazar, and the available literature about the role of PPARα and γ in rodent carcinogenesis, we propose a mode of action hypothesis for the carcinogenic effect of PPARα+γ agonists in the rat urothelium, which combines receptor-mediated and off-target cytotoxic effects. The proposed mode of action hypothesis is being explored in our laboratories, towards understanding the human relevance of the rat cancer findings, and developing rapid in vitro or short-term in vivo screening approaches to faciliate development of new dual-acting PPAR agonist compounds

Molecular genetics of pulmonary hypertension in children

Until recently, the molecular aetiology of paediatric pulmonary hypertension (PH) was relatively poorly understood. While the TGF-β/BMP pathway was recognised as central to disease progression, genetic analyses in children were largely confined to targeted screening of risk genes in small cohorts, with clinical management extrapolated from adult data. In recent years, next-generation sequencing has highlighted notable differences in the genetic architecture underlying childhood-onset cases, with a higher genetic burden in children partly explained by comorbidities such as congenital heart disease. Here, we review recent genetic advances in paediatric PH and highlight important risk factors such as dysregulation of the transcription factors SOX17 and TBX4. Given the poorer prognosis in paediatric cases, molecular diagnosis offers a vital tool to enhance clinical care of children with PH