Static testing of large scale ground support panels

The Western Australian School of Mines (WASM) developed a large area static test facility to enable the evaluation of three forms of surface support; namely, mesh, shotcrete and membranes. The purpose of this thesis is to document the test conditions and procedures under which these tests were conducted and to document the outcomes from testing.A review of previous mesh testing established that the most common method used for the evaluation of mesh types was two-dimensional linear elastic analyses, often using catenary principles. These analysis techniques have been used to estimate the tension in the wires of mesh and the strength characteristics of the mesh. These methods assume that forces are only transferred along directly loaded wires and that failure of the mesh is only related to the tensile strength of the wire.The force – displacement response from fully restrained mesh tests conducted at the WASM test facility have been characterised into distinct phases, clearly demonstrating the non-linear behaviour of mesh. The initial force response to displacement is slow; however the force response increases dramatically with further displacement. This behaviour has been shown to follow a cubic relationship.The force – displacement results have also been used to develop load transfer concepts for both weld mesh and chain link mesh. These concepts suggest that forces are transferred away from the directly loaded wires through adjoining wires, distributing forces over a greater area of the mesh. The force capacity of the weld mesh is not only dependent on the tensile strength of the wire but also the quality of the welding process. Likewise, the force capacity of chain link mesh is not only dependent on the tensile strength of the wire but also diamond configuration which allows load to be shared across a greater area of mesh.Several other test conditions were evaluated as part of the test program, including mesh sheet overlaps and wire orientation. The results have demonstrated that the boundary conditions and mesh orientation alters the force – displacement response of mesh.Most current shotcrete testing techniques focus on quality assurance and quality control. Shotcrete support mechanism and failure mechanisms are complex and not well understood. The WASM punch test method was developed to evaluate shotcrete using realistic shotcrete failure mechanisms such as shear and flexural failure and adhesion loss.The behaviour of shotcrete is characterised by an initial stiff reaction followed by rupture of the cement matrix. Rupture generally occurs at displacements of less than 5mm. The rupture force of fibre reinforced shotcrete is dependent only on the cement content of the shotcrete mix and the thickness of the layer, and not on the fibre type. The post rupture reaction of shotcrete is dependent on the reinforcing material; namely fibres or mesh. Mesh reinforced shotcrete had much greater force and displacement capacity compared with fibre reinforced shotcrete.Membranes have two theoretical support models (Norcroft, 2006); namely, the membrane support model and the beam support model. A total of 6 tests were undertaken to investigate the behaviour of a particular membrane product under the two theoretical support models. These tests were aimed at determining a suitable test method that could determine the capacity of the membrane and the behaviour of the membrane under realistic loading conditions.The results from both test programs demonstrated that the membrane has limited force and displacement capacity and cannot be compared with conventional mesh and shotcrete as suggested in the product data sheet. The failure mechanism was shear failure with minimal adhesion loss observed.The development of the WASM test facility has enabled the evaluation and comparison of various surface support elements. The results of this testing have provide a valuable insight into the performance of each of the individual products

DETERMINATION OF ENERGY ABSORPTION CAPABILITIES OF LARGE SCALE SHOTCRETE PANELS

The Western Australian School of Mines (WASM) has developed a facility for the static testing of full scale ground support elements. The test facility consists of several stiff steel frames used to support the sample and a screw feed jack is used to load the sample. A large scale punch test method has been developed to evaluate various shotcrete mix designs at different curing times. The shotcrete is sprayed on to a sandstone substrate containing an isolated disc that is centrally located. The test sample is placed on to the sample frame and restrained on all sides. The disc is displaced at a constant rate by the screw feed jack which in turn loads the sample. Instruments measure the displacement and the load being applied to the sample through the loading disc. The test method has been used to compare the force – displacement properties of different mix designs and reinforcing materials including plastic fibres, steel fibres and mesh. The force – displacement properties have been used to determine the energy absorbing capability of fibrecrete systems

The impact of over 80 years of land cover changes on bee and wasp pollinator communities in England

Change in land cover is thought to be one of the key drivers of pollinator declines, and yet there is a dearth of studies exploring the relationships between historical changes in land cover and shifts in pollinator communities. Here, we explore, for the first time, land cover changes in England over more than 80 years, and relate them to concurrent shifts in bee and wasp species richness and community composition. Using historical data from 14 sites across four counties, we quantify the key land cover changes within and around these sites and estimate the changes in richness and composition of pollinators. Land cover changes within sites, as well as changes within a 1 km radius outside the sites, have significant effects on richness and composition of bee and wasp species, with changes in edge habitats between major land classes also having a key influence. Our results highlight not just the land cover changes that may be detrimental to pollinator communities, but also provide an insight into how increases in habitat diversity may benefit species diversity, and could thus help inform policy and practice for future land management

Colouration in amphibians as a reflection of nutritional status : the case of tree frogs in Costa Rica

Colouration has been considered a cue for mating success in many species; ornaments in males often are related to carotenoid mobilization towards feathers and/or skin and can signal general health and nutrition status. However, there are several factors that can also link with status, such as physiological blood parameters and body condition, but there is not substantial evidence which supports the existence of these relationships and interactions in anurans. This study evaluated how body score and blood values interact with colouration in free-range Agalychnis callidryas and Agalychnis annae males. We found significant associations between body condition and plasmatic proteins and haematocrit, as well as between body condition and colour values from the chromaticity diagram. We also demonstrated that there is a significant relation between the glucose and plasmatic protein values that were reflected in the ventral colours of the animals, and haematocrit inversely affected most of those colour values. Significant differences were found between species as well as between populations of A. callidryas, suggesting that despite colour variation, there are also biochemical differences within animals from the same species located in different regions. These data provide information on underlying factors for colouration of male tree frogs in nature, provide insights about the dynamics of several nutrients in the amphibian model and how this could affect the reproductive output of the animals

A multi-center population-based case–control study of ovarian cancer in African-American women: the African American Cancer Epidemiology Study (AACES)

Abstract: Background: Ovarian cancer (OVCA) is the leading cause of death from gynecological cancer, with poorer survival for African American (AA) women compared to whites. However, little is known about risk factors for OVCA in AA. To study the epidemiology of OVCA in this population, we started a collaborative effort in 10 sites in the US. Here we describe the study and highlight the challenges of conducting a study of a lethal disease in a minority population. Methods: The African American Cancer Epidemiology Study (AACES) is an ongoing, population-based case–control study of OVCA in AA in 10 geographic locations, aiming to recruit 850 women with invasive epithelial OVCA and 850 controls age- and geographically-matched to cases. Rapid case ascertainment and random-digit-dialing systems are in place to ascertain cases and controls, respectively. A telephone survey focuses on risk factors as well as factors of particular relevance for AAs. Food-frequency questionnaires, follow-up surveys, biospecimens and medical records are also obtained. Results: Current accrual of 403 AA OVCA cases and 639 controls exceeds that of any existing study to date. We observed a high proportion (15%) of deceased non-responders among the cases that in part is explained by advanced stage at diagnosis. A logistic regression model did not support that socio-economic status was a factor in advanced stage at diagnosis. Most risk factor associations were in the expected direction and magnitude. High BMI was associated with ovarian cancer risk, with multivariable adjusted ORs and 95% CIs of 1.50 (0.99-2.27) for obese and 1.27 (0.85- 1.91) for morbidly obese women compared to normal/underweight women. Conclusions: AACES targets a rare tumor in AAs and addresses issues most relevant to this population. The importance of the study is accentuated by the high proportion of OVCA cases ascertained as deceased. Our analyses indicated that obesity, highly prevalent in this population (>60% of the cases), was associated with increased OVCA risk. While these findings need to be replicated, they suggest the potential for an effective intervention on the risk in AAs. Upon completion of enrollment, AACES will be the largest epidemiologic study of OVCA in AA women

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN