Experimental and Computational Failure Analysis of Graphite/Bismaleimide Laminated Composite and Carbon Foam in Sandwich Construction

Sandwich beams consisting of a carbon foam core and graphite/bismaleimide face sheets were constructed and tested. Nine specimens were fabricated using three distinct cross-ply symmetric face sheet layups with a constant core thickness. Four-point bend testing controlled by a constant rate of midspan vertical displacement was used to load the specimens to failure. Displacements and strains from the experiment were compared to analytical sandwich beam theory and displacements and failure loads were compared to a layerwise finite element solution. A phenomenological failure criterion was developed that compares favorably with experimental failure data. The finite element solution gives failure within an average of 7.58% of experiment and a stiffness within an average of 11.16%. The analytical sandwich beam theory predicts stiffness within 4.83% of experiment and strain within 5.27% of experiment. This research shows that the finite element theory has the ability to predict failure onset and location in a sandwich structure and that the face sheet layups within higher stiffness delay the onset of shear failure in the core

An application of the requirement vs capability analysis to estimating design reliability of solid rocket motors

Design reliability parameters for solid propellant rocket engine

Synchronized single electron emission from dynamical quantum dots

We study synchronized quantized charge pumping through several dynamical quantum dots (QDs) driven by a single time modulated gate signal. We show that the main obstacle for synchronization being the lack of uniformity can be overcome by operating the QDs in the decay cascade regime. We discuss the mechanism responsible for lifting the stringent uniformity requirements. This enhanced functionality of dynamical QDs might find applications in nanoelectronics and quantum metrology.Comment: 4 pages, 3 figures, submitted to AP

Integrated quantized electronics: a semiconductor quantized voltage source

The Josephson effect in superconductors links a quantized output voltage Vout = f \cdot(h/2e) to the natural constants of the electron's charge e, Planck's constant h, and to an excitation frequency f with important applications in electrical quantum metrology. Also semiconductors are routinely applied in electrical quantum metrology making use of the quantum Hall effect. However, despite their broad range of further applications e.g. in integrated circuits, quantized voltage generation by a semiconductor device has never been obtained. Here we report a semiconductor quantized voltage source generating quantized voltages Vout = f\cdot(h/e). It is based on an integrated quantized circuit of a single electron pump operated at pumping frequency f and a quantum Hall device monolithically integrated in series. The output voltages of several \muV are expected to be scalable by orders of magnitude using present technology. The device might open a new route towards the closure of the quantum metrological triangle. Furthermore it represents a universal electrical quantum reference allowing to generate quantized values of the three most relevant electrical units of voltage, current, and resistance based on fundamental constants using a single device.Comment: 15 pages, 3 figure

Diurnal inhibition of NMDA-EPSCs at rat hippocampal mossy fibre synapses through orexin-2 receptors.

Diurnal release of the orexin neuropeptides orexin-A (Ox-A, hypocretin-1) and orexin-B (Ox-B, hypocretin-2) stabilises arousal, regulates energy homeostasis and contributes to cognition and learning. However, whether cellular correlates of brain plasticity are regulated through orexins, and whether they do so in a time-of-day-dependent manner, has never been assessed. Immunohistochemically we found sparse but widespread innervation of hippocampal subfields through Ox-A- and Ox-B-containing fibres in young adult rats. The actions of Ox-A were studied on NMDA receptor (NMDAR)-mediated excitatory synaptic transmission in acute hippocampal slices prepared around the trough (Zeitgeber time (ZT) 4-8, corresponding to 4-8 h into the resting phase) and peak (ZT 23) of intracerebroventricular orexin levels. At ZT 4-8, exogenous Ox-A (100 nm in bath) inhibited NMDA receptor-mediated excitatory postsynaptic currents (NMDA-EPSCs) at mossy fibre (MF)-CA3 (to 55.6 ± 6.8% of control, P = 0.0003) and at Schaffer collateral-CA1 synapses (70.8 ± 6.3%, P = 0.013), whereas it remained ineffective at non-MF excitatory synapses in CA3. Ox-A actions were mediated postsynaptically and blocked by the orexin-2 receptor (OX2R) antagonist JNJ10397049 (1 μm), but not by orexin-1 receptor inhibition (SB334867, 1 μm) or by adrenergic and cholinergic antagonists. At ZT 23, inhibitory effects of exogenous Ox-A were absent (97.6 ± 2.9%, P = 0.42), but reinstated (87.2 ± 3.3%, P = 0.002) when endogenous orexin signalling was attenuated for 5 h through i.p. injections of almorexant (100 mg kg(-1)), a dual orexin receptor antagonist. In conclusion, endogenous orexins modulate hippocampal NMDAR function in a time-of-day-dependent manner, suggesting that they may influence cellular plasticity and consequent variations in memory performance across the sleep-wake cycle

High abundances of neurotrophin 3 in atopic dermatitis mast cell

<p>Abstract</p> <p>Background</p> <p>Neurotrophin 3 (NT-3) is a member of the neurotrophin family, a group of related proteins that are known to regulate neuro-immune interactions in allergic diseases. Their cellular sources and role in the recruitment of mast cell precursors in atopic dermatitis have not been characterized in detail so far.</p> <p>Objective</p> <p>Characterize NT-3 on a transcriptional and translational level in individuals with atopic dermatitis with special focus on mast cells.</p> <p>Methods</p> <p>To meet this objective NT-3 levels in the serum of AD patients were measured, the effect of NT-3 on keratinocytes was evaluated and the gene expression and regulation assessed using ELISA, immunohistochemistry and RNA quantification.</p> <p>Results</p> <p>Systemic levels of NT-3 were found to be higher in individuals with AD as compared to healthy controls. A distinct genetic expression was found in the various cells of the skin. In lesional mast cells of individuals with atopic dermatitis an increased amount of NT-3 was apparent. Functional <it>in vitro </it>experiments demonstrated that NT-3 stimulation led to a suppression of IL-8 secretion by HaCat cells.</p> <p>Conclusion</p> <p>These findings could imply a role for NT-3 in the pathogenesis of allergic skin diseases.</p

Carbon Stable Isotope Analysis of Bison Dentition

Understanding how bison behaved in the past can provide key insights for today\u27s managers, ecologists, and anthropologists. However, the direct application of both historic documentation and modern field observations may not provide the necessary insights for understanding bison behaviors in archeological and paleontological contexts. In order to develop a better understanding of possible behavior within these contexts, we have developed individual foraging histories for 22 Bison bison from the Glenrock Buffalo Jump assemblage of the Plains Late Prehistoric period in Wyoming and four Pleistocene B. priscus from the Ukraine. Incremental stable carbon isotopic values of dental enamel were used to determine foraging histories. The progressive development of enamel allows for samples to be selected that represent distinct periods of an individual\u27s life. Comparison of these dietary patterns among members of a herd can demonstrate foraging behaviors of cohorts and, in turn, the entire assemblage. Application of this high resolution paleodietary technique provides new information on bison behaviors in a paleontological and archaeological context

The Missing Angle: Ecosystem Consequences of Phenological Mismatch

Climate change leads to unequal shifts in the phenology of interacting species, such as consumers and their resources, leading to potential phenological mismatches. While studies have investigated how phenological mismatch affects wild populations, we still lack studies and a framework for investigating how phenological mismatch affects ecosystems, particularly nutrient cycling

Galaxy merger histories and the role of merging in driving star formation at z>1

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We use Horizon-AGN, a hydrodynamical cosmological simulation, to explore the role of mergers in the evolution of massive (M > 10^10 MSun) galaxies around the epoch of peak cosmic star formation (1zR(4:1 3 are 'blue' (i.e. have significant associated star formation), the proportion of 'red' mergers increases rapidly at ztodays stellar mass was formed.Peer reviewe