2,360 research outputs found

    Sensitive rhyolitic pyroclastic deposits in the Tauranga region: mineralogy, geomechanics and microstructure of peak and remoulded states

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    Soil sensitivity has previously been recognised as a significant contributor to soil failures both internationally and within New Zealand, particularly in the Tauranga region. Sensitive soils are characterised by initial high peak shear strength, yet very low remoulded shear strength. While international sensitive soils have been well characterised, the nature of sensitivity in rhyolitic deposits in New Zealand is poorly understood. This study characterises both sensitive and non-sensitive rhyolitic tephra derived soil samples from the Tauranga region in order to identify the fundamental differences in the materials between states of peak and remoulded strength. Field and laboratory investigations were undertaken to analyse sensitivity. Field investigations included shear vane testing for the quantification of sensitivity, and stratigraphic profiling. Laboratory testing comprised geotechnical testing (particularly shear strength and Atterberg limits), petrographic observations through scanning electron microscopy (SEM) and X-ray diffraction (XRD), and measurement of the rheology of remoulded sensitive materials. Five localities were used in this study. Three sites were considered sensitive (Omokoroa, Te Puna and Pahoia Peninsula), while the remaining two (Rangataua Bay and Tauriko) were considered non-sensitive on the basis of the Milne et al. (Milne, J.D.G.; Clayden, B.; Singleton, P.L.; Wilson, A.D. 1995: Soil description handbook. Manaaki Whenua Press, Lincoln, Canterbury) sensitivity test. Field observations showed sensitive material is of tephric origin, likely associated with the Te Puna Ignimbrite (~ 0.93 Ma). The deposits considered generally classify as sensitive to extra sensitive (7-15) with no samples being identified as quick. The non-sensitive material has characteristically different field behaviour where the material does not release moisture, or flow, upon remoulding. The non-sensitive material is associated with the Te Ranga Ignimbrite (~ 0.27 Ma). Moisture contents are typically high for the sensitive materials, always exceeding their respective liquid limits (liquidity indices > 1), while the opposite is true for the non-sensitive samples. Porosity is also high for the sensitive materials (> 61 %), whereas non-sensitive materials return lower porosity values of < 60 %. Characterising the peak strength state of the sensitive materials, triaxial testing show consistent effective cohesion and friction angles ranging between 8–16 kPa and 28–41 ⁰, respectively. Viscometric flow characteristics indicate that pH adjustment has a critical impact on remoulded sensitive material: typically as the pH becomes more alkaline, clay particle association is reduced and the soil weakens further, while with increased acidity there is a small increase in yield stress. XRD indicates that all materials are dominated by halloysite. The wet to saturated rhyolitic materials promote a silica-rich environment that is slow draining, leading to favourable conditions for halloysite formation over other clay minerals. Most commonly, halloysite was observed in sphere, tube and to a lesser extent, plate morphologies. SEM, XRD and EDX analyses revealed previously undocumented, large (~ 60 µm–~ 1.5 mm) halloysite books in selected sensitive materials. The books are hypothesised to have formed from the incorporation of iron into the halloysite unit cell to form plate morphologies, followed by Ostwald ripening under conditions of low iron in the soil solution, and coalescence during a relatively dry period to form the large books. The soil microstructure of the sensitive materials in comparison with the non-sensitive soils appears to provide the critical distinction in determining the variation between the peak to remoulded strength characteristics for the sensitive material. The sensitive material is comprised of similar sized small spheres and short, stubby tubular halloysite morphologies. These pack inefficiently, producing a low density of packing. Such an arrangement produces many small micropores which facilitate the development of high moisture contents, producing liquidity indices > 1. The primary microstructure is matrix-skeletal for sensitive samples. The non-sensitive samples are comprised of large spheres and long, thin tubular halloysite morphologies. These particles pack much more efficiently, where the tubes fill the voids produced between large spherical formations. The result is a much tighter structural arrangement in the clay fraction, with reduced potential for high moisture contents to build up, leading to liquidity indices < 1. The non-sensitive material typically displays a matrix microstructure. Upon remoulding, the structure of the sensitive material was broken down and appeared continuous. Connectors were typically destroyed, while tubes, plates and books were broken into smaller remnants. The similar sized spherical and tubular particles appeared to be easily mobilised following disturbance where they would fail in a fluidised manner from the high moisture held within the sample. The non-sensitive material, however, indicated very little change upon remoulding. The clay particle interactions were still arranged in a tight structure, which did not breakdown sufficiently to become entrained within the available moisture. The sensitivity of rhyolitic tephra, therefore, is primarily attributed to the relative size and packing of the halloysite particle morphologies. The low density of packing produced an open structure, allowing for high moisture contents to develop, which following remoulding, leads to irreversible structural breakdown and release of stored water, promoting flow characteristics of the soil and thus high sensitivity

    Assessing housing quality and its impact on health, safety and sustainability

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    Background The adverse health and environmental effects of poor housing quality are well established. A central requirement for evidence-based policies and programmes to improve housing standards is a valid, reliable and practical way of measuring housing quality that is supported by policy agencies, the housing sector, researchers and the public. Methods This paper provides guidance on the development of housing quality-assessment tools that link practical measures of housing conditions to their effects on health, safety and sustainability, with particular reference to tools developed in New Zealand and England. Results The authors describe how information on housing quality can support individuals, agencies and the private sector to make worthwhile improvements to the health, safety and sustainability of housing. The information gathered and the resultant tools developed should be guided by the multiple purposes and end users of this information. Other important issues outlined include deciding on the scope, detailed content, practical administration issues and how the information will be analysed and summarised for its intended end users. There are likely to be considerable benefits from increased international collaboration and standardisation of approaches to measuring housing hazards. At the same time, these assessment approaches need to consider local factors such as climate, geography, culture, predominating building practices, important housing-related health issues and existing building codes. Conclusions An effective housing quality-assessment tool has a central role in supporting improvements to housing. The issues discussed in this paper are designed to motivate and assist the development of such tools

    Landslides in sensitive soils, Tauranga, New Zealand.

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    In the Tauranga region sensitive soil failures commonly occur after heavy rainfall events, causing considerable infrastructure damage. Several notable landslides include a large failure at Bramley Drive, Omokoroa in 1979, the Ruahihi Canal collapse in 1981, and numerous landslides in May 2005; recently the Bramley Drive scarp was reactivated in 2011. These failures are associated with materials loosely classified as the Pahoia Tephras - a mixture of rhyolitic pyroclastic deposits of approximately 1 Ma. The common link with extreme rainfall events suggests a pore water pressure control on the initiation of these failures. Recent research on the structure of the soils shows a dominance of halloysite clay minerals packed loosely in arrangements with high porosity (51 – 77 %), but with almost entirely micropores. This leads us to conclude that the permeability is very low, and the materials remain continuously wet. The formation of halloysite is encouraged by a wet environment with no episodes of drying, supporting this assumption. A high-resolution CPT trace at Bramley Drive indicates induced pore water pressures rising steadily to a peak at approximately 25 m depth; this depth coincides with the base of the landslide scarp. We infer that elevated pore water pressures develop within this single, thick aquifer, triggering failure through reduced effective stresses. The inactive halloysite clay mineral results in low plasticity indices (13 – 44 %) and hence high liquidity indices (1.2 – 2.4) due to the saturated pore space; remoulding following failure is sudden and dramatic and results in large debris runout distances

    The Stat3-Fam3a axis promotes muscle stem cell myogenic lineage progression by inducing mitochondrial respiration.

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    Metabolic reprogramming is an active regulator of stem cell fate choices, and successful stem cell differentiation in different compartments requires the induction of oxidative phosphorylation. However, the mechanisms that promote mitochondrial respiration during stem cell differentiation are poorly understood. Here we demonstrate that Stat3 promotes muscle stem cell myogenic lineage progression by stimulating mitochondrial respiration in mice. We identify Fam3a, a cytokine-like protein, as a major Stat3 downstream effector in muscle stem cells. We demonstrate that Fam3a is required for muscle stem cell commitment and skeletal muscle development. We show that myogenic cells secrete Fam3a, and exposure of Stat3-ablated muscle stem cells to recombinant Fam3a in vitro and in vivo rescues their defects in mitochondrial respiration and myogenic commitment. Together, these findings indicate that Fam3a is a Stat3-regulated secreted factor that promotes muscle stem cell oxidative metabolism and differentiation, and suggests that Fam3a is a potential tool to modulate cell fate choices

    Population diversity and relatedness in Sugarbirds (Promeropidae: Promerops spp.)

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    Copyright 2018 Haworth et al. Distributed under Creative Commons CC-BY 4.0Sugarbirds are a family of two socially-monogamous passerine species endemic to southern Africa. Cape and Gurney’s Sugarbird (Promerops cafer and P. gurneyi) differ in abundance, dispersion across their range and in the degree of sexual dimorphism in tail length, factors that affect breeding systems and potentially genetic diversity. According to recent data, P. gurneyi are in decline and revision of the species’ IUCN conservation status to a threatened category may be warranted. It is therefore necessary to understand genetic diversity and risk of inbreeding in this species. We used six polymorphic microsatellite markers and one mitochondrial gene (ND2) to compare genetic diversity in P. cafer from Helderberg Nature Reserve and P. gurneyi from Golden Gate Highlands National Park, sites at the core of each species distribution. We describe novel universal avian primers which amplify the entire ND2 coding sequence across a broad range of bird orders. We observed high mitochondrial and microsatellite diversity in both sugarbird populations, with no detectable inbreeding and large effective population sizes.publishedVersio

    Unmanned Aircraft System Assessments of Landslide Safety for Transportation Corridors

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    An assessment of unmanned aircraft systems (UAS) concluded that current, off-the-shelf UAS aircraft and cameras can be effective for creating the digital surface models used to evaluate rock-slope stability and landslide risk along transportation corridors. The imagery collected with UAS can be processed using a photogrammetry technique called Structure-from-Motion (SfM) which generates a point cloud and surface model, similar to terrestrial laser scanning (TLS). We treated the TLS data as our control, or “truth,” because it is a mature and well-proven technology. The comparisons of the TLS surfaces and the SFM surfaces were impressive – if not comparable is many cases. Thus, the SfM surface models would be suitable for deriving slope morphology to generate rockfall activity indices (RAI) for landslide assessment provided the slopes. This research also revealed that UAS are a safer alternative to the deployment and operation of TLS operating on a road shoulder because UAS can be launched and recovered from a remote location and capable of imaging without flying directly over the road. However both the UAS and TLS approaches still require traditional survey control and photo targets to accurately geo-reference their respective DSM.List of Figures ...................................................................................................... vi List of Abbreviations ......................................................................................... vii Acknowledgments ................................................................................................ x Executive Summary ............................................................................................. xi CHAPTER 1 INTRODUCTION .......................................................................... 1 CHAPTER 2 LITERATURE REVIEW ................................................................ 4 2.1 Landslide Hazards .................................................................................... 4 2.2 Unmanned Aircraft Systems Remote Sensing.......................................... 6 2.3 Structure From Motion (SfM) .................................................................. 7 2.4 Lidar terrain mapping ............................................................................... 8 CHAPTER 3 STUDY SITE/DATA .................................................................. 11 CHAPTER 4 METHODS ................................................................................ 13 4.1 Data Collection ............................................................................................. 13 4.1.1 Survey Control ..................................................................................... 14 4.1.2 TLS Surveys ........................................................................................ 16 4.1.3 UAS Imagery ....................................................................................... 17 4.1.4 Terrestrial Imagery Acquisition ........................................................... 19 4.2 Data Processing ............................................................................................ 20 4.2.1 Survey Control ..................................................................................... 20 4.2.2 TLS Processing .................................................................................... 20 4.2.3 SfM Processing .................................................................................... 21 4.2.4 Surface Generation .............................................................................. 22 4.3 Quality Evaluation ........................................................................................ 23 4.3.1 Completeness ....................................................................................... 23 4.3.2 Data Density/Resolution ...................................................................... 23 4.3.3 Accuracy Assessment .......................................................................... 23 4.3.2 Surface Morphology Analysis ............................................................. 24 4.2.6 Data Visualization ............................................................................... 25 CHAPTER 5 RESULTS ................................................................................. 27 v 5.1 UTIC DSM evaluation.................................................................................. 27 5.1.1 Completeness evaluation ..................................................................... 28 5.1.2 Data Density Evaluation ...................................................................... 29 5.1.3 Accuracy Evaluation............................................................................ 30 5.2 Geomorphological Evaluation ...................................................................... 32 CHAPTER 6 DISCUSSION ............................................................................ 35 6.1 Evaluation of UAS efficiencies .................................................................... 35 6.2 DSM quality and completeness .................................................................... 37 6.3 Safety and operational considerations .......................................................... 37 CHAPTER 7 CONCLUSIONS AND RECOMMENDATIONS ................................ 40 7.1 Technology Transfer..................................................................................... 41 7.1.1 Publications ......................................................................................... 41 7.1.2 Presentations ........................................................................................ 42 7.1.3 Multi-media outreach .......................................................................... 43 6.4 Integration of UAS and TLS data ................................................................. 44 REFERENCES .............................................................................................. 4

    Characterization of a Novel Small Molecule Subtype Specific Estrogen-Related Receptor α Antagonist in MCF-7 Breast Cancer Cells

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    The orphan nuclear receptor estrogen-related receptor alpha (ERRalpha) is a member of the nuclear receptor superfamily. It was identified through a search for genes encoding proteins related to estrogen receptor alpha (ERalpha). An endogenous ligand has not been found. Novel ERRalpha antagonists that are highly specific for binding to the ligand binding domain (LBD) of ERRalpha have been recently reported. Research suggests that ERRalpha may be a novel drug target to treat breast cancer and/or metabolic disorders and this has led to an effort to characterize the mechanisms of action of N-[(2Z)-3-(4,5-dihydro-1,3-thiazol-2-yl)-1,3-thiazolidin-2-yl idene]-5H dibenzo[a,d][7]annulen-5-amine, a novel ERRalpha specific antagonist.We demonstrate this ERRalpha ligand inhibits ERRalpha transcriptional activity in MCF-7 cells by luciferase assay but does not affect mRNA levels measured by real-time RT-PCR. Also, ERalpha (ESR1) mRNA levels were not affected upon treatment with the ERRalpha antagonist, but other ERRalpha (ESRRA) target genes such as pS2 (TFF1), osteopontin (SPP1), and aromatase (CYP19A1) mRNA levels decreased. In vitro, the ERRalpha antagonist prevents the constitutive interaction between ERRalpha and nuclear receptor coactivators. Furthermore, we use Western blots to demonstrate ERRalpha protein degradation via the ubiquitin proteasome pathway is increased by the ERRalpha-subtype specific antagonist. We demonstrate by chromatin immunoprecipitation (ChIP) that the interaction between ACADM, ESRRA, and TFF1 endogenous gene promoters and ERRalpha protein is decreased when cells are treated with the ligand. Knocking-down ERRalpha (shRNA) led to similar genomic effects seen when MCF-7 cells were treated with our ERRalpha antagonist.We report the mechanism of action of a novel ERRalpha specific antagonist that inhibits transcriptional activity of ERRalpha, disrupts the constitutive interaction between ERRalpha and nuclear coactivators, and induces proteasome-dependent ERRalpha protein degradation. Additionally, we confirmed that knocking-down ERRalpha lead to similar genomic effects demonstrated in vitro when treated with the ERRalpha specific antagonist
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