2,933 research outputs found

    Experimental Studies of the NaCs 53Π0 and a3Σ+ States

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    We report high resolution measurements of 372 NaCs 53Π0(v, J) ro-vibrational level energies in the range 0 ≤ v ≤ 22. The data have been used to construct NaCs 53Π0 potential energy curves using the Rydberg–Klein-Rees and inverted perturbation approximation methods. Bound-free 53Π0(v, J) → 1(a)3Σ+ emission has also been measured, and is used to determine the repulsive wall of the 1(a)3Σ+ state and the 53Π0 → 1(a)3Σ+ relative transition dipole moment function. Hyperfine structure in the 53Π0 state has not been observed in this experiment. This null result is explained using a simple vector coupling model

    Thoracic Injury Effects Of Linear And Angular Karate Impacts

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    Skilled karate practitioners are reputed to be able to completely disable an opponent with one blow -- when necessary. Immediate questions arise as to whether karate participants: (a) can, in fact, deliver disabling injurious blows to the thorax, (b) can have a greater ability to damage the body with some technique types over others, and (c) can wear readily available safety equipment to temper blows to below the level of medically severe injury. The viscous response criteria (VCmax), based on chest compression and compression velocity, has been devised to estimate level of injury to the thorax or chest. Accordingly, a VCmax =1.0 m/s is the level for a 25% probability of severe injury, such as liver or lung laceration. Twelve international class karate competitors of 3rd, 4th, and 5th degree or higher (master class) black belt ranks, were evaluated impacting the thorax of an instrumented anthropometric test dummy (ATD) to determine the probable injury effects of linear (thrusting) and angular (striking or snapping) types of karate blows, with and without a chest protector. Techniques evaluated were the roundhouse kick, backfist strike, side-thrust kick, and the reverse punch. Data were analyzed using a 2*3*4 ANOVA design with Tukey's Studentized Range follow-up tests to discriminate within condition differences. The adjusted viscous response (VCmax) was the variable used for evaluation. Of the three skill classes evaluated, 3rd (M =1.2096, SD =.5309) and 4th (M =1.1127, SD =.4304) degree ranks generated statistically higher VCmax levels than master class competitors (M =.8036, SD =.2797) across all conaitions, F (2, 60) =7.57, F = .0012. The chest protector was found to be effective, F 0,60) =4.28, F =.0430, in attenuating the impact effects below the serious injury level (M =1.1382, SD = .4423 and M =.9535, SD = .4575, without and with the chest protector, respectively). The roundhouse kick (M =1.3778, SD =.4674) generated higher .VCmax than all other techniques, F (3, 60) =7.17, F = .0003,: the reverse punch (M =1.0122, SD =.3923); the side-thrust kick (M =.9538, SD =.4976); or the backfist strike (M =.8189, SD =.2986). No statistical difference was detected among the technique conditions. It was concluded that the highly skilled karate competitor could deliver severe or greater levels of damage to the thorax with karate techniques, especially the roundhouse kick. The level of damage to the thorax can be reduced below the "serious" level with the use of a chest protector

    Status report on a natural laminar-flow nacelle flight experiment

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    The natural laminar flow (NLF) nacelle experiment is part of a drag reduction production program, and has the dual objectives of studying the extent of NLF on full scale nacelles in a flight environment and the effect of acoustic disturbance on the location of transition on the nacelle surface. The experiment is being conducted in two phases: (1) an NLF fairing was flown on a full scale Citation nacelle to develop the experiment technique and establish feasibility; (2) full scale, flow through, NLF nacelles located below the right wing of an experimental NASA OV-1 aircraft are evaluated. The measurements of most interest are the static pressure distribution and transition location on the nacelle surface, and the fluctuating pressure levels associated with the noise sources. Data are collected in combinations of acoustic frequencies and sound pressure levels. The results of phase 2 tests to date indicate that on shape GE2, natural laminar flow was maintained as far aft as the afterbody joint at 50 percent of the nacelle length. An aft facing step at this joint caused premature transition at this station. No change was observed in the transition pattern when the noise sources were operated

    Geospatial analysis and living urban geometry

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    This essay outlines how to incorporate morphological rules within the exigencies of our technological age. We propose using the current evolution of GIS (Geographical Information Systems) technologies beyond their original representational domain, towards predictive and dynamic spatial models that help in constructing the new discipline of "urban seeding". We condemn the high-rise tower block as an unsuitable typology for a living city, and propose to re-establish human-scale urban fabric that resembles the traditional city. Pedestrian presence, density, and movement all reveal that open space between modernist buildings is not urban at all, but neither is the open space found in today's sprawling suburbs. True urban space contains and encourages pedestrian interactions, and has to be designed and built according to specific rules. The opposition between traditional self-organized versus modernist planned cities challenges the very core of the urban planning discipline. Planning has to be re-framed from being a tool creating a fixed future to become a visionary adaptive tool of dynamic states in evolution

    Geochemical characterisation of northern Norwegian fjord surface sediments: a baseline for further paleo-environmental investigations

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    Norwegian fjord sediments are promising archives for very high resolution records of past environmental changes. Recent investigations of the modern depositional environment within fjords revealed that the accurate quantification of the inputs, sources, and sedimentary preservation of organic and inorganic material is crucial to decipher long term past climate signals in the sedimentary record of a certain fjord. Here, we investigate the elemental composition, bulk mineral assemblage and grain size distribution of forty-one surface sediment samples from a northern Norwegian fjord system. We reveal modern geochemical and sedimentological processes that occur within the Vestfjord, Ofotfjord and Tysfjord. Our results indicate a very heterogeneous sediment supply and intricate sedimentation processes. We propose that this is related to the complex fjord bathymetry, a low hydrodynamic energy environment, differences in the hinterland bedrock composition and a relatively small drainage area causing a rather diffuse freshwater inflow. Moreover, we show that marine carbonate productivity is the main calcite and Ca source in all three fjords

    Predictable arguments of knowledge

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    We initiate a formal investigation on the power of predictability for argument of knowledge systems for NP. Specifically, we consider private-coin argument systems where the answer of the prover can be predicted, given the private randomness of the verifier; we call such protocols Predictable Arguments of Knowledge (PAoK). Our study encompasses a full characterization of PAoK, showing that such arguments can be made extremely laconic, with the prover sending a single bit, and assumed to have only one round (i.e., two messages) of communication without loss of generality. We additionally explore PAoK satisfying additional properties (including zero-knowledge and the possibility of re-using the same challenge across multiple executions with the prover), present several constructions of PAoK relying on different cryptographic tools, and discuss applications to cryptography

    Fjords as Aquatic Critical Zones (ACZs)

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    In recent decades, the land-ocean aquatic continuum, commonly defined as the interface, or transition zone, between terrestrial ecosystems and the open ocean, has undergone dramatic changes. On-going work has stressed the importance of treating Aquatic Critical Zones (ACZs) as a sensitive system needing intensive investigation. Here, we discuss fjords as an ACZ in the context of sedimentological, geochemical, and climatic impacts. These diverse physical features of fjords are key in controlling the sources, transport, and burial of organic matter in the modern era and over the Holocene. High sediment accumulation rates in fjord sediments allow for high-resolution records of past climate and environmental change where multiple proxies can be applied to fjord sediments that focus on either marine or terrestrial-derived components. Humans through land-use change and climatic stressors are having an impact on the larger carbon stores in fjords. Sediment delivery whether from accelerating erosion (e.g. mining, deforestation, road building, agriculture) or from sequestration of fluvial sediment behind dams has been seriously altered in the Anthropocene. Climate change affecting rainfall and river discharge into fjords will impact the thickness and extent of the low-salinity layer in the upper reaches of the fjord, slowing the rate of the overturning circulation and deep-water renewal – thereby impacting bottom water oxygen concentrations

    All-Atomic Molecular Dynamic Studies of Human and Drosophila CDK8: Insights into Their Kinase Domains, the LXXLL Motifs, and Drug Binding Site

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    Cyclin-dependent kinase 8 (CDK8) and its regulatory partner Cyclin C (CycC) play conserved roles in modulating RNA polymerase II (Pol II)-dependent gene expression. To understand the structure and function relations of CDK8, we analyzed the structures of human and Drosophila CDK8 proteins using molecular dynamics simulations, combined with functional analyses in Drosophila. Specifically, we evaluated the structural differences between hCDK8 and dCDK8 to predict the effects of the LXXLL motif mutation (AQKAA), the P154L mutations, and drug binding on local structures of the CDK8 proteins. First, we have observed that both the LXXLL motif and the kinase activity of CDK8 are required for the normal larval-to-pupal transition in Drosophila. Second, our molecular dynamic analyses have revealed that hCDK8 has higher hydrogen bond occupation of His149-Asp151 and Asp151-Asn156 than dCDK8. Third, the substructure of Asp282, Phe283, Arg285, Thr287 and Cys291 can distinguish human and Drosophila CDK8 structures. In addition, there are two hydrogen bonds in the LXXLL motif: a lower occupation between L312 and L315, and a relatively higher occupation between L312 and L316. Human CDK8 has higher hydrogen bond occupation between L312 and L316 than dCDK8. Moreover, L312, L315 and L316 in the LXXLL motif of CDK8 have the specific pattern of hydrogen bonds and geometries, which could be crucial for the binding to nuclear receptors. Furthermore, the P154L mutation dramatically decreases the hydrogen bond between L312 and L315 in hCDK8, but not in dCDK8. The mutations of P154L and AQKAA modestly alter the local structures around residues 154. Finally, we identified the inhibitor-induced conformational changes of hCDK8, and our results suggest a structural difference in the drug-binding site between hCDK8 and dCDK8. Taken together, these results provide the structural insights into the roles of the LXXLL motif and the kinase activity of CDK8 in vivo
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