957 research outputs found

    ABC Interview of Senators Muskie, Baker, and Nelson Following President Nixon\u27s State of the Union Address

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    Senators Muskie, Baker, and Nelson answer questions on the environment in an interview by ABC following Nixon\u27s State of the Union address

    Subcritical Flow at Open Channel Structures Open Channel Expansions

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    Analyzing the hydraulics of open channel constrictions has been modified to allow the analysis of energy loss in open channel expansions. The modified technique has been compared with previous methods of analysis using data collected in the laboratory on open channel expansions with vertical walls, and triangular-shaped baffles. Also, a design procedure for such baffled outlet structures has been developed

    A new dynamic module for in-situ nanomechanical testing at high strain rate

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    In-situ nanomechanical testing is commonly used to probe surface mechanical properties of bulk materials or thin films, like hardness, Young’s modulus, Yield stress
Actually most of the instruments can measure these properties only statically, i.e. a low frequency, leading to property measurement only at low strain rate (usually 10-1s-1 by nanoindentation). This is mainly caused by the low resonance frequency of the system, preventing making tests at higher speed. Performing high dynamic measurements could bring new information on materials properties like deformation mechanism at high strain rate, or high dynamic fatigue properties. A new high dynamic module usable for in-situ mechanical testing has been developed. It is composed of a small piezotube attached directly behind the tip. Because of the small dimensions of the module, his resonance frequency is very high (higher than 50kHz) in comparison to classical nanomechanical testers, permitting to perform and measure precisely the signals at very high frequency. Moreover, it can be used as a sensor and as an actuator, in x, y and z directions which gives to this module a very large range of measurements. Firstly, the characteristics, the performances and the limits of the new high dynamic module will be presented. Secondly some indentations experiments performed at high strain rate on nanocrystalline nickel with the in-situ nanomechanical tester (Alemnis Gmbh) equipped with the high dynamic will be presented and discussed (Fig. 1). Finally, some micropillar compression at high strain rate on the same material will be described and discussed

    Tube Models for Rubber-Elastic Systems

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    In the first part of the paper we show that the constraining potentials introduced to mimic entanglement effects in Edwards' tube model and Flory's constrained junction model are diagonal in the generalized Rouse modes of the corresponding phantom network. As a consequence, both models can formally be solved exactly for arbitrary connectivity using the recently introduced constrained mode model. In the second part, we solve a double tube model for the confinement of long paths in polymer networks which is partially due to crosslinking and partially due to entanglements. Our model describes a non-trivial crossover between the Warner-Edwards and the Heinrich-Straube tube models. We present results for the macroscopic elastic properties as well as for the microscopic deformations including structure factors.Comment: 15 pages, 8 figures, Macromolecules in pres

    Does Self-Compassion Protect Adolescents from Stress?

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    The aim of this study was to determine whether adolescents who were high in self-compassion self-reported different levels of emotional wellbeing than adolescents who were low in self-compassion, and to determine whether those high in self-compassion responded differently under a lab social stressor than those low in self-compassion. In a lab setting, participants (age 13–18; n = 28) completed the Trier Social Stress Test (TSST) and physiological stress was assessed via salivary cortisol, heart rate, blood pressure, and heart rate variability at baseline, during the TSST, and during recovery. After completing the lab protocol, an email was sent to participants that provided a link to an online survey which was composed of emotional wellbeing measures including perceived stress, life satisfaction, positive and negative affect. After conducting repeated measure ANOVAS to determine that the TSST induced a significant stress response, the sample was split at the median of self-compassion. T tests were conducted to determine meaningful differences (Hedges’ g > .20) between the groups. Findings indicated that those in the high self-compassion group (≄the median) self-reported greater emotional wellbeing than those in the low self-compassion group (<the median). Overall, those in the high self-compassion group also had a lower physiologic stress response when exposed to the TSST than those in the low self-compassion group. Regression analyses were also conducted; baseline self-compassion predicted self-reported emotional wellbeing, but did not predict physiological response to the TSST. Findings support the potential buffering effect that self-compassion may have in protecting adolescents from social stressors; yet more research needs to be conducted in larger samples to confirm and replicate these findings

    Massively parallel computing on an organic molecular layer

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    Current computers operate at enormous speeds of ~10^13 bits/s, but their principle of sequential logic operation has remained unchanged since the 1950s. Though our brain is much slower on a per-neuron base (~10^3 firings/s), it is capable of remarkable decision-making based on the collective operations of millions of neurons at a time in ever-evolving neural circuitry. Here we use molecular switches to build an assembly where each molecule communicates-like neurons-with many neighbors simultaneously. The assembly's ability to reconfigure itself spontaneously for a new problem allows us to realize conventional computing constructs like logic gates and Voronoi decompositions, as well as to reproduce two natural phenomena: heat diffusion and the mutation of normal cells to cancer cells. This is a shift from the current static computing paradigm of serial bit-processing to a regime in which a large number of bits are processed in parallel in dynamically changing hardware.Comment: 25 pages, 6 figure
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