1,401 research outputs found
The White Stone Band of the Kimmeridge Clay Formation, an integrated high resolution approach to understanding environmental change
The Kimmeridge Clay is a Jurassic mudrock succession that shows Milankovitch Band climatic cyclicity. A key issue is to determine how the subtle changes that define this cyclicity result from climatic change. Using material from the Natural Environment Research Council Rapid Global Geological Events (RGGE) Kimmeridge Drilling Project boreholes, the White Stone Band was investigated at the lamination scale using backscattered electron imagery and quantitative palynofacies. Fabric analysis shows the lamination to represent successive deposition of coccolith-rich and organic-matter-rich layers. Individual laminae contain unsorted palynological debris with a consistent ratio of marine and terrestrial components. Such mixed organic matter input is interpreted as the result of storm transport. Linking water column processes to laminae deposition suggests seasonal input with a coccolith bloom followed by a more diverse assemblage including dinoflagellates and photosynthetic chlorobiacean bacteria. As the photic zone extended into the euxinic water column organic matter export to the sea bed underwent minimal cycling through oxidation and subsequently became preserved through sulphurization with greatly increased sequestration of carbon. This was significantlyincreased by late season storm-driven mixing of euxinic water into the photic zone. Increased frequency ofstorm systems would therefore dilute the coccolith input to give an oil shale. Hence climatically induced changes in storm frequency would progressively vary the organic content of the sediment and generate the climate cycle signal. Keywords: Milankovitch theory, Kimmeridge Clay, organic matter, high-resolution methods, climate change
Puromycin aminonucleoside induces oxidant-dependent DNA damage in podocytes in vitro and in vivo
A decline in podocyte number correlates with progression to glomerulosclerosis. A mechanism underlying reduced podocyte number is the podocyte's relative inability to proliferate in response to injury. Injury by the podocyte toxin puromycin aminonucleoside (PA) is mediated via reactive oxygen species (ROS). The precise role of ROS in the pathogenesis of PA-induced glomerulosclerosis remains to be determined. We sought to examine whether PA-induced ROS caused podocyte DNA damage, possibly accounting for the podocyte's inability to proliferate in response to PA. In vitro, podocytes were exposed to PA, with or without the radical scavenger 1,3-dimethyl-2-thiourea (DMTU). In vivo, male Sprague–Dawley rats were divided into experimental groups (n=6/group/time point): PA, PA with DMTU, and control, killed at days 1.5, 3, or 7. DNA damage was measured by DNA precipitation, apurinic/apyrimidinic site, Comet, and 8-hydroxydeoxyguanosine assays. Cell cycle checkpoint protein upregulation (by immunostaining and Western blotting), histopathology, and biochemical parameters were examined. DNA damage was increased in cultured podocytes that received PA, but not PA with DMTU. PA exposure activated specific cell cycle checkpoint proteins, with attenuation by DMTU. DNA repair enzymes were activated, providing evidence for attempted DNA repair. The PA-treated animals developed worse proteinuria and histopathologic disease and exhibited more DNA damage than the DMTU pretreated group. No significant apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining. A mechanism underlying the lack of podocyte proliferation following PA-induced injury in vitro and in vivo may be ROS-mediated DNA damage, with upregulation of specific cell cycle checkpoints leading to cell cycle arrest
Collection of anthropometry from older and physically impaired persons: traditional methods versus TC2 3-D body scanner
With advances in technology it is now possible to collect a wide range of anthropometric data, to a high degree of accuracy, using 3D light-based body scanners. This gives the potential to speed up the collection of anthropometric data for design purposes, to decrease processing time and data input required, and to reduce error due to inaccuracy of measurements taken using more traditional methods and equipment (anthropometer, stadiometer and sitting height table). However, when the data collection concerns older and/or physically impaired people there are serious issues for consideration when deciding on the best method to collect anthropometry. This paper discusses the issues arising when collecting data using both traditional methods of data collection and a first use by the experimental team of the TC2 3D body scanner, when faced with a ‘non-standard’ sample, during an EPSRC funded research project into issues surrounding transport usage by older and physically impaired people. Relevance to industry: Designing products, environments and services so that the increasing ageing population, as well as the physically impaired, can use them increases the potential market. To do this, up-to-date and relevant anthropometry is often needed. 3D light-based bodyscanners offer a potential fast way of obtaining this data, and this paper discusses some of the issues with using one scanner with older and disabled people
Biotic analogies for self-organising cities
Nature has inspired generations of urban designers and planners in pursuit of harmonious and functional built environments. Research regarding self-organisation has encouraged urbanists to consider the role of bottom-up approaches in generating urban order. However, the extent to which self-organisation-inspired approaches draw directly from nature is not always clear. Here, we examined the biological basis of urban research, focusing on self-organisation. We conducted a systematic literature search of self-organisation in urban design and biology, mapped the relationship between key biological terms across the two fields and assessed the quality and validity of biological comparisons in the urban design literature. Finding deep inconsistencies in the mapping of central terms between the two fields, a preponderance for cross-level analogies and comparisons that spanned molecules to ecosystems, we developed a biotic framework to visualise the analogical space and elucidate areas where new inspiration may be sought
Risk-Sensitive Diagnosis and the Role of Neural Networks
Diagnostic problem solving, whether it be fault-diagnosis in an engineering system or diagnosis of a disease in human beings, is a prime example of decision making in the face of uncertainty. Frequently, many different outcomes may correspond to an identical set of measured data or symptoms. The converse may also be true, that any given diagnosis may correspond to a number of distinct sets of diagnostic data. In addition, the data themselves may be imprecise adding to the overall uncertainty in the reasoning process, making it probablistic in nature. These factors can often be the cause of poor diagnostic accuracy and in part responsible for the difficulty in developing useful and usable diagnostic support systems. Furthermore, it would be unusual for diagnostic errors to be viewed as equally acceptable. For example, a large number of false alarms may be tolerable in the dignosis of heart attack when the decision to be made is simply admit to hospital or not. The level of acceptability changes though, when the decision to be made is whether or not to administer potentially life-threatening drugs. Evidently, the risk associated with an incorrect diagnosis is crucial to making a decision about treatment...........
Dentin tubule numerical density variations below the CEJ
Aim: To evaluate dentin tubule numerical density variations below the CEJ. Methodology: Three human non-carious permanent canines were sectioned parallel to the CEJ to obtain dentin disks 1 mm thick whose surfaces were 1 mm and 2 mm below the CEJ. Each disk was sectioned into quarters resulting in four segment locations: facial, lingual, mesial, and distal. The outer (PDL side) and inner (pulp side) surfaces of the specimens were shaped to expose dentin with SiC papers and polished. Numerical tubule density was determined from SEM images. All data were statistically analyzed using a three-way ANOVA. Results: The dentin tubule density (number/mm2) ranged from 13,700 to 32,300. Dentin tubule density was relatively uniform at 1 mm and 2 mm below the CEJ and increased by a factor of about two from the outer to the inner surface, which was significantly different (P < 0.0001). Conclusions: The tubule density variations at the cervical root did not present marked
Neural Networks, Heart Attack and Bayesian Decisions: An Application of the Boltzmann Perceptron Network
A decision aid is proposed for the diagnosis of the most commonly occurring cause of emergency admission to hospital in the developed world-acute myocardial infarction, or heart attack. The motivation for the proposal lies in the Bayesian ( minimum risk)decision theory which is briefly reviewed. The fact that many feedforward artificial neural networks are known to estimate the conditional class probabilities required for Bayesian decision theory is explored and one candidate-the Boltzmann Perceptron Network-is selected as possessing the most desirable properties. A brief account of the theory (based upon the so-called Boltzmann machine) underlying this little known network is presented.
The Boltzmann Perceptron Network is trained to diagnose the presence or absence of myocardial infarction on data gathered from a large UK teaching hospital and is found to perform as well as senior registras with specific cardiological training (diagnostic accuracy in excess of 80%). In addition, the Boltzmann Perceptron Network is found to provide greater user confidence than the multi-layer Perceptron
Identification and Characterization of a Novel Human Myeloid Inhibitory C-type Lectin-like Receptor (MICL) That Is Predominantly Expressed on Granulocytes and Monocytes
Inhibitory and activatory C-type lectin-like receptors play an important role in immunity through the regulation of leukocytes. Here, we report the identification and characterization of a novel myeloid inhibitory C-type lectin-like receptor (MICL) whose expression is primarily restricted to granulocytes and monocytes. This receptor, which contains a single C-type lectin-like domain and a cytoplasmic immunoreceptor tyrosine-based inhibitory motif, is related to LOX-1 (lectin-like receptor for oxidized low density lipoprotein-1) and the β-glucan receptor (Dectin-1) and is variably spliced and highly N-glycosylated. We demonstrate that it preferentially associates with the signaling phosphatases SHP-1 and SHP-2, but not with SHIP. Novel chimeric analyses with a construct combining MICL and the β-glucan receptor show that MICL can inhibit cellular activation through its cytoplasmic immunoreceptor tyrosine-based inhibitory motff. These data suggest that MICL is a negative regulator of granulocyte and monocyte function
Laboratory Validation of Two Wearable Sensor Systems for Measuring Head Impact Severity in Football Players
Wearable sensors can measure head impact frequency and magnitude in football players. Our goal was to quantify the impact detection rate and validity of the direction and peak kinematics of two wearable sensors: a helmet system (HITS) and a mouthguard system (X2). Using a linear impactor, modified Hybrid-III headform and one helmet model, we conducted 16 impacts for each system at 12 helmet sites and 5 speeds (3.6–11.2 m/s) (N = 896 tests). Peak linear and angular accelerations (PLA, PAA), head injury criteria (HIC) and impact directions from each device were compared to reference sensors in the headform. Both sensors detected ~96% of impacts. Median angular errors for impact directions were 34° for HITS and 16° for X2. PLA, PAA and HIC were simultaneously valid at 2 sites for HITS (side, oblique) and one site for X2 (side). At least one kinematic parameter was valid at 2 and 7 other sites for HITS and X2 respectively. Median relative errors for PLA were 7% for HITS and -7% for X2. Although sensor validity may differ for other helmets and headforms, our analyses show that data generated by these two sensors need careful interpretation
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