345 research outputs found
Extent of the Ross Orogen in Antarctica: new data from DSDP 270 and Iselin Bank
The Ross Sea is bordered by the Late Precambrian–Cambrian Ross–Delamerian Orogen of East Antarctica and the more Pacific-ward Ordovician–Silurian Lachlan–Tuhua–Robertson Bay–Swanson Orogen. A calcsilicate gneiss from Deep Sea Drilling Project 270 drill hole in the central Ross Sea, Antarctica, gives a U-Pb titanite age of 437 ± 6 Ma (2σ). This age of high-grade metamorphism is too young for typical Ross Orogen. Based on this age, and on lithology, we propose a provisional correlation with the Early Palaeozoic Lachlan–Tuhua–Robertson Bay–Swanson Orogen, and possibly the Bowers Terrane of northern Victoria Land. A metamorphosed porphyritic rhyolite dredged from the Iselin Bank, northern Ross Sea, gives a U-Pb zircon age of 545 ± 32 Ma (2σ). The U-Pb age, petrochemistry, Ar-Ar K-feldspar dating, and Sr and Nd isotopic ratios indicate a correlation with Late Proterozoic–Cambrian igneous protoliths of the Ross Orogen. If the Iselin Bank rhyolite is not ice-rafted debris, then it represents a further intriguing occurrence of Ross basement found outside the main Ross–Delamerian Orogen
Elastomer and resin replicas for sem observation of metallic materials
The replica technique is often used to study damage evolution at the surface of specimens or industrial components and understand the physicial phenomena responsible for fatigue crack initiation before failure. Replicas are usually made from acetate cellulose film. This paper presents an alternative technique generally used by archaeologists to study lithic use-wear and bone modification. A mold is made from a dental elastomer (silicon based impression material) and a positive replica is made by casting epoxy resin in the mold. Comparative SEM analysis of damaged metallic specimens and their resin replicas show that this technique provides a good resolution and preserves details up to 0.5 micrometer. This easy and low cost method allows a systematic study of micro-crack growth
Battery draining attacks against edge computing nodes in IoT networks
Many IoT devices, especially those deployed at the network edge have limited power resources. In this work, we study the effects of a variety of battery draining attacks against edge nodes. Specifically, we implemented hello flooding, packet flooding, selective forwarding, rank attack, and versioning attack in ContikiOS and simulated them in the Cooja simulator. We consider a number of relevant metrics, such as CPU time, low power mode time, TX/RX time, and battery consumption. Besides, we test the stretch attack with three different batteries as an extreme scenario. Our results show that versioning attack is the most severe in terms of draining the power resources of the network, followed by packet flooding and hello flooding attacks. Furthermore, we find that selective forwarding and rank attacks are not able to considerably increase the power resource usage in our scenarios. By quantifying the effects of these attacks, we demonstrate that under specific scenarios, versioning attack can be three to four times as effective as packet flooding and hello flooding attacks in wasting network resources. At the same time, packet flooding is generally comparable to hello flooding in CPU and TX time usage increase but twice as powerful in draining device batteries
What have we learnt from EUPORIAS climate service prototypes?
The international effort toward climate services, epitomised by the development of the Global Framework for Climate Services and, more recently the launch of Copernicus Climate Change Service has renewed interest in the users and the role they can play in shaping the services they will eventually use. Here we critically analyse the results of the five climate service prototypes that were developed as part of the EU funded project EUPORIAS.
Starting from the experience acquired in each of the projects we attempt to distil a few key lessons which, we believe, will be relevant to the wider community of climate service developers
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Genome-wide analysis of ETS-family DNA-binding in vitro and in vivo
Peer reviewe
An Automated Method to Quantify Microglia Morphology and Application to Monitor Activation State Longitudinally In Vivo
Microglia are specialized immune cells of the brain. Upon insult, microglia initiate a cascade of cellular responses including a characteristic change in cell morphology. To study the dynamics of microglia immune response in situ, we developed an automated image analysis method that enables the quantitative assessment of microglia activation state within tissue based solely on cell morphology. Per cell morphometric analysis of fluorescently labeled microglia is achieved through local iterative threshold segmentation, which reduces errors caused by signal-to-noise variation across large volumes. We demonstrate, utilizing systemic application of lipopolysaccharide as a model of immune challenge, that several morphological parameters, including cell perimeter length, cell roundness and soma size, quantitatively distinguish resting versus activated populations of microglia within tissue comparable to traditional immunohistochemistry methods. Furthermore, we provide proof-of-concept data that monitoring soma size enables the longitudinal assessment of microglia activation in the mouse neocortex imaged via 2-photon in vivo microscopy. The ability to quantify microglia activation automatically by shape alone allows unbiased and rapid analysis of both fixed and in vivo central nervous system tissue
Charting two centuries of transformation in a coastal social-ecological system: a mixed methods approach
This is the final version. Available on open access from Elsevier via the DOI in this recordOyster reef ecosystems used to form significant components of many temperate and subtropical inshore coastal systems but have suffered declines globally, with a concurrent loss of services. The early timing of many of these changes makes it difficult to determine restoration targets which consider interdecadal timeframes, community values and shifted baselines. On the Australian continent, however, the transition from Indigenous (Aboriginal) to Westernized resource use and management occurred relatively recently, allowing us to map social-ecological changes in detail. In this study, we reconstruct the transformations in the Sydney rock oyster (Saccostrea glomerata) wild commercial industry of southeast Queensland, and by extension its reef ecosystems, as well as the changing societal and cultural values related to the presence and use of the rock oyster through time. By integrating data from the archaeological, anthropological and fisheries literature, government and media accounts, we explore these transformations over the last two centuries. Before the 1870s, there was a relative equilibrium. Aboriginal peoples featured as sole traders to Europeans, supplying oysters and becoming a substantial component of the industry’s labour pool. Effectively, Australia’s commercial oyster industry arose from Aboriginal-European trade. During this initial phase, there was still a relative abundance of wild oyster, with subtidal oyster reef structures present in regions where oysters are today absent or scarce. By contrast, these reefs declined by the late 19th 23 century, despite production of oysters increasing due to continued large-scale oyster recruitment and the expansion of oyster cultivation in intertidal areas. Production peaked in 1891, with successive peaks observed in regions further north. During the 1890s, flood events coupled with land-use changes introduced large quantities of silt into the system, which likely facilitated an increase in oyster pests and diseases, ultimately decreasing the carrying capacity of the system. Today oyster production in this region is less than one-tenth of historical peak production. Many cultural heritage components have also been lost. Indigenous management is now very minor due to the massive decimation of Aboriginal populations and their respective practices. Yet, we found strong cultural attachment to midden remains and oyster production continues within Indigenous communities, with considerable broader community support. This study highlights the value of conducting thorough analysis of early media accounts as a means for reconstructing historical resource decline and management. It further demonstrates the application of historical information and context for contemporary management, protection and restoration of much-altered coastal social-ecological systems
Inactivation of promoter 1B of APC causes partial gene silencing: evidence for a significant role of the promoter in regulation and causative of familial adenomatous polyposis
Familial adenomatous polyposis (FAP) is caused by germline mutations in the adenomatous polyposis coli (APC) gene. Two promoters, 1A and 1B, have been recognized in APC, and 1B is thought to have a minor role in the regulation of the gene. We have identified a novel deletion encompassing half of this promoter in the largest family (Family 1) of the Swedish Polyposis Registry. The mutation leads to an imbalance in allele-specific expression of APC, and transcription from promoter 1B was highly impaired in both normal colorectal mucosa and blood from mutation carriers. To establish the significance of promoter 1B in normal colorectal mucosa (from controls), expression levels of specific transcripts from each of the promoters, 1A and 1B, were examined, and the expression from 1B was significantly higher compared with 1A. Significant amounts of transcripts generated from promoter 1B were also determined in a panel of 20 various normal tissues examined. In FAP-related tumors, the APC germline mutation is proposed to dictate the second hit. Mutations leaving two or three out of seven 20-amino-acid repeats in the central domain of APC intact seem to be required for tumorigenesis. We examined adenomas from mutation carriers in Family 1 for second hits in the entire gene without any findings, however, loss of the residual expression of the deleterious allele was observed. Three major conclusions of significant importance in relation to the function of APC can be drawn from this study; (i) germline inactivation of promoter 1B is disease causing in FAP; (ii) expression of transcripts from promoter 1B is generated at considerable higher levels compared with 1A, demonstrating a hitherto unknown importance of 1B; (iii) adenoma formation in FAP, caused by impaired function of promoter 1B, does not require homozygous inactivation of APC allowing for alternative genetic models as basis for adenoma formation
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