Bimetallic (Ni<sub>x</sub>Mg<sub>1−x</sub>)-MOF-74 stabilizes Ni<sup>2+</sup> open metal site relative to Ni-MOF-74, resulting in a highly active and selective alcohol dehydrogenation catalyst.
This chapter examines the military applications of nuclear power plants. It examines their historical dimension, their present status and likely future applications. The US armed forces are looking at reducing power supply vulnerabilities and operating costs, and also reducing petroleum dependence. During their operations in Iraq and Afghanistan, the US armed forces had difficulty in getting huge quantities of fuel for the power needs of remote operating bases. The National Aeronautical and Space Administration (NASA) reportedly uses some of these to power satellites and other spacecraft. The nuclear reactors and/or fissile material will also have to be safeguarded from possible theft or capture by terrorist groups. Nuclear-powered submarines have small reactors that provide propulsion. Their advantage over conventional diesel-electric submarines is based on the fact that they are independent of air and do not need to surface off and on to run the diesel generator to charge the batteries.
This paper provides a rigorous mathematical proof that the double scroll is indeed chaotic. Our approach is to derive a linearly equivalent class of piecewise-linear differential equations which includes the double scroll as a special case. A necessary and sufficient condition for two such piecewise-linear vector fields to be linearly equivalent is that their respective eigenvalues be a scaled version of each other. In the special case where they are identical, we have exact equivalence in the sense of linear conjugacy. An explicit normalform equation in the context of global bifurcation is derived and parametrized by their eigenvalues. Analytical expressions for various Poincaré maps are then derived and used to characterize the birth and the death of the double scroll, as well as to derive an approximate one-dimensional map in analytic form which is useful for further bifurcation analysis. In particular, the analytical expressions characterizing various half-return maps associated with the Poincaré map are used in a crucial way to prove the existence of a Shilnikov-type homoclinic orbit, thereby establishing rigorously the chaotic nature of the double scroll. These analytical expressions are also fundamental in our in-depth analysis of the birth (onset of the double scroll) and death (extinction of chaos) of the double scroll. The unifying theme throughout this paper is to analyze the double scroll system as an unfolding of a large family of piecewise-linear vector fields in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R^3</tex> . Using this approach, we were able to prove that the chaotic dynamics of the double scroll is quite common, and is robust because the associated horseshoes predicted from Shilnikov's theorem are structurally stable. In fact, it is exhibited by a large family (in fact, infinitely many linearlyequivalent circuits) of vector fields whose associated piecewise-linear differential equations bear no resemblance to each other. It is therefore remarkable that the normalized eigenvalues, which is a local concept, completely determine the system's global qualitative behavior.
In this paper, we present an object recognition technique using scanline information. Objects are scanned using a small number of on/off light sensors. The times when the beams break and unbreak constrain the object's identity, position, and orientation. We study this type of sensor because they are inexpensive, compact, very precise, and insensitive to ambient light, and so well-adapted to manufacturing environments. The information provided by the sensor is very sparse however, consisting of isolated points on the object boundary without normal information. Conventional model-based matching techniques, such as the alignment method, take O(n<SUP>3</SUP>) time for this problem. We describe an O(A + n) correspondence algorithm for objects with convex polygonal silhouettes, where n is the silhouette's complexity, and A is the total number of consistent edge pair matches for pairs of scanline points, which is O(n<SUP>2</SUP>) in the worst case, but typically O(n). Our algorithm works also for non-convex objects, but the quantity A has a somewhat larger typical value, and a worst case value of O(n<SUP>3</SUP>). The object's position and orientation can be easily computed given the correspondence information.
Protected by the chiral symmetry, three dimensional chiral topological insulators are characterized by an integer-valued topological invariant. How this invariant could emerge in physical observables is an important question. Here we show that the magneto-electric polarization can identify the integer-valued invariant if we gap the system without coating a quantum Hall layer on the surface. The quantized response is demonstrated to be robust against weak perturbations. We also study the topological properties by adiabatically coupling two nontrivial phases, and find that gapless states appear and are localized at the boundary region. Finally, an experimental scheme is proposed to realize the Hamiltonian and measure the quantized response with ultracold atoms in optical lattices.
Abstract Background The combination of sarcopenia and obesity has been associated with physical impairment in older people. However, previous research has relied on assessments of lean mass as a surrogate for muscle mass. We postulate that inaccurate measures of muscle mass may have obscured the role of obesity in sarcopenia and related outcomes. Our aim was to clarify the interactions of muscle and fat with physical performance and adverse outcomes using an accurate measure of muscle mass. Methods In a longitudinal study of &gt;1,300 older men (mean age 84 years), we compared a direct measurement of muscle mass (D3 creatine dilution; D3Cr) with an approximation of muscle mass (appendicular lean mass [ALM] by dual-energy x-ray absorptiometry [DXA]) and their associations with measures of physical performance (gait speed, chair stand time) and adverse outcomes (incident injurious falls and mobility problems). We measured percent fat mass by DXA. Results Low D3Cr muscle mass was strongly associated with decreased performance and increased risk of adverse outcomes. Increased fat mass had little association after accounting for D3Cr muscle mass. In contrast, DXA ALM was minimally associated with performance or adverse outcomes, and fatness remained associated with both outcomes after accounting for DXA ALM. Conclusions When an accurate assessment of muscle mass (rather than lean mass) is used, reduced muscle mass is highly associated with important outcomes and the negative effects of adiposity are minimal, suggesting that obesity has little relevance for the understanding of important adverse health outcomes of sarcopenia in older men.
Organic electronics are broadly anticipated to impact the development of flexible thin-film device technologies. Among these, solution-processable π-conjugated polymers and small molecules are proving particularly promising in field-effect transistors and bulk heterojunction solar cells. This Perspective analyzes some of the most exciting strategies recently suggested in the design and structural organization of π-functional materials for transistor and solar cell applications. Emphasis is placed on the interplay between molecular structure, self-assembling properties, nanoscale and mesoscale ordering, and device efficiency parameters. A critical look at the various approaches used to optimize both materials and device performance is provided to assist in the identification of new directions and further advances.
Distinctive, massive to stratified, pale blue volcaniclastics, initially referred to as the "blue tuff," were encountered at all four sites drilled during ODP Leg 127 in the Japan Sea. Detailed vertical sequence analysis, plagioclase chemistry, plagioclase 87Sr/86Sr isotopic composition, and 40Ar/39Ar age dating indicate that thick sequences of the blue tuff are not genetically related.Blue tuffs at Hole 794B were apparently deposited by density flows at ambient temperature. Deposition was penecontemporaneous with a large submarine phreatomagmatic eruption at 14.9 Ma in bathyal or deeper water depths. The blue tuffs at this location comprise mostly reworked hydroclastic glass shards and lesser amounts of plagioclase crystals. Pyrogenic plagioclase has an average An mole% of 18±3. Comparison of blue tuff plagioclase compositions with the composition of plagioclase from acoustic basement at Site 794 suggests that these rocks are not genetically related. As such, the extrapolation of sediment accumulation rate data in conjunction with this more precise age for the blue tuff corroborates previous minimum age estimates of 16.2 Ma for acoustic basement at Site 794.Blue tuffs at Hole 796B were probably deposited at ambient temperatures by downslope slumping and density flow of reworked pyrogenic debris. This debris includes abundant bubble wall glass shards and plagioclase crystals, with variable admixture of volcanic lithic and intrabasinal fragments. Pyrogenic fragments were produced by subaerial or shallow submarine, magmatic eruptions dated at 7.6 Ma. Blue tuffs contain a heterogeneous mixture of unrelated fragments including a mixed population of plagioclase crystals. The average An mole% of the predominant, probable comagmatic, plagioclase population is 30±4.The two sequences of blue tuff studied are distinct in age, mineral composition, and the eruptive origin of pyroclastic fragments. Preliminary 87Sr/86Sr isotopic compositions of plagioclase, however, indicates that blue tuffs at both locations are the product of typical, subduction-related island arc magmatism. Based on the results of this study, there is no justification for stratigraphic correlation of widespread, Miocene, blue to blue-gray bentonitic tuff and tuffaceous sandstones nor the interpretation that these strata are indicative of regional, explosive submarine volcanism genetically related to rifting and formation of the Japan Sea. Rather, these reworked pyroclastic strata of intermediate composition were deposited over a protracted 6-8 m.y. period in association with widespread, subduction-related submarine to subaerial volcanism in the Japan Sea backarc basin.
Abstract Introduction An abundance of cross-sectional research links inadequate sleep with poor emotional health, but experimental studies in children are rare. Further, the impact of sleep loss is not uniform across individuals, and pre-existing anxiety might potentiate the effects of poor sleep on children’s emotional functioning. Methods N=53 children (mean age 9.0 years; 56% female) completed multi-modal, emotional assessments in the lab when rested and after two nights of sleep restriction (7h and 6h in bed, respectively). Sleep was monitored with polysomnography and actigraphy. Subjective reports of affect and arousal, psychophysiological reactivity, and objective emotional expression were examined during two emotional processing tasks, including one where children were asked to suppress their emotional responses. Results After sleep restriction, deleterious alterations were observed in children’s affect and their emotional reactivity, expression, and regulation. These effects were primarily limited to positive emotional stimuli. The presence of anxiety symptoms moderated most of the alterations in emotional processing observed after sleep restriction. Conclusion Results suggest inadequate sleep preferentially impacts positive compared to negative emotion in pre-pubertal children and that pre-existing anxiety symptoms amplify these effects. Implications for children’s everyday socio-emotional lives and long-term affective risk are highlighted. Support NIMH grant #R21MH099351
Systematic methods for synthesising nonlinear networks having a prescribed scalar or multidimensional piecewise-linear function are described. In the scalar case, precision active-circuit building blocks using operational amplifiers, transistors, diodes, and resistors are given for realising piecewise-linear drivingpoint and transfer characteristic plots. In the multidimensional case, methods are given for realising a multiterminal nonlinear network having a multidimensional piecewise-linear transfer function. Finally, these methods are generalised for synthesising nonlinear n-ports having a prescribed multidimensional piecewiselinear driving-point function. Although most of the basic building blocks are grounded active networks, convertor networks are developed for transforming such grounded networks into floating networks having the same properties. By slight modifications of these convertor networks, other useful conversion properties are also presented
