13,495 research outputs found
Evaluating Morphological Computation in Muscle and DC-motor Driven Models of Human Hopping
In the context of embodied artificial intelligence, morphological computation
refers to processes which are conducted by the body (and environment) that
otherwise would have to be performed by the brain. Exploiting environmental and
morphological properties is an important feature of embodied systems. The main
reason is that it allows to significantly reduce the controller complexity. An
important aspect of morphological computation is that it cannot be assigned to
an embodied system per se, but that it is, as we show, behavior- and
state-dependent. In this work, we evaluate two different measures of
morphological computation that can be applied in robotic systems and in
computer simulations of biological movement. As an example, these measures were
evaluated on muscle and DC-motor driven hopping models. We show that a
state-dependent analysis of the hopping behaviors provides additional insights
that cannot be gained from the averaged measures alone. This work includes
algorithms and computer code for the measures.Comment: 10 pages, 4 figures, 1 table, 5 algorithm
Using timescales to interpret dissolved oxygen distributions in the bottom waters of Chesapeake Bay
A simplified conceptual model based on timescales of gravitational circulation, vertical exchange, and total oxygen consumption rate of the biochemical processes is presented to provide insight into the relationships between estuarine dynamics and bottom water dissolved oxygen (DO). Two dimensionless parameters are introduced to diagnose the relationship between the vertical exchange process and the biochemical DO consumption and the influence of gravitational circulation on replenishment of bottom DO. The relative magnitudes of these timescales provide a linkage between the physical and biochemical processes. The hypoxic and anoxic conditions in deep waters of Chesapeake Bay are successfully interpreted with these three proposed timescales. Because the Bay is a long estuary, the replenishment of the bottom DO due to gravitational circulation diminishes as the bottom water travels farther upstream. The bottom DO is mainly modulated by the vertical exchange process in the middle and upper portions of the Bay. In addition to other physical processes that affect vertical exchange, wind and freshwater are the major predictors of the vertical exchange time. The model is applicable to Chesapeake Bay and other estuaries with persistent gravitational circulation if the dimensionless parameters can be appropriately estimated
Ultimate behavior of idealized composite floor elements at ambient and elevated temperature
This paper is concerned with the ultimate behavior of composite floor slabs under extreme loading situations resembling those occurring during severe building fires. The study focuses on the failure state associated with rupture of the reinforcement in idealized slab elements, which become lightly reinforced in a fire situation due to the early loss of the steel deck. The paper describes a fundamental approach for assessing the failure limit associated with reinforcement fracture in lightly reinforced beams, representing idealized slab strips. A description of the ambient-temperature tests on isolated restrained elements, carried out to assess the influence of key material parameters on the failure conditions, is firstly presented. The results of a series of material tests, undertaken mainly to examine the effect of elevated temperature on ductility, are also described. A simplified analytical model is employed, in conjunction with the experimental findings, to assess the salient material parameters and their implications on the ultimate response at both ambient and elevated temperature. © 2009 Springer Science+Business Media, LLC
On acceleration of Krylov-subspace-based Newton and Arnoldi iterations for incompressible CFD: replacing time steppers and generation of initial guess
We propose two techniques aimed at improving the convergence rate of steady
state and eigenvalue solvers preconditioned by the inverse Stokes operator and
realized via time-stepping. First, we suggest a generalization of the Stokes
operator so that the resulting preconditioner operator depends on several
parameters and whose action preserves zero divergence and boundary conditions.
The parameters can be tuned for each problem to speed up the convergence of a
Krylov-subspace-based linear algebra solver. This operator can be inverted by
the Uzawa-like algorithm, and does not need a time-stepping. Second, we propose
to generate an initial guess of steady flow, leading eigenvalue and eigenvector
using orthogonal projection on a divergence-free basis satisfying all boundary
conditions. The approach, including the two proposed techniques, is illustrated
on the solution of the linear stability problem for laterally heated square and
cubic cavities
Analisa Kinerja Keuangan pada Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri Periode 2014-2017
The research aims to find out and describe finance performance in Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri period 2014-2017. This research using quantitative descriptive research. The data used in this research is secondary data are derived from the financial statements Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri period 2014-2017. Data analysis technique used was fiancial ratio analysis. The result show that finance performance in Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri period 2014-2017 based on the ratio of earning indicate the cooperatives are in less good condition. Finance performance in Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri period 2014-2017 based on the ratio of activities shows the cooperative is in bad condition. Finance performance in Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri period 2014-2017 based on liquidity ratios indicate the cooperatives are in less good condition. Finance performance in Koperasi Pegawai Republik Indonesia Kantor Urusan Agama Kabupaten Wonogiri period 2014-2017 based on solvency ratios indicate the cooperatives are in less good condition.
Keywords: Finance Performance, Earning Ratio, Activity Ratio, Liquidity Ratio, Solvency Rati
Melatonin prevents cytosolic calcium overload, mitochondrial damage and cell death due to toxically high doses of dexamethasone-induced oxidative stress in human neuroblastoma SH-SY5Y cells
Stressor exposure activates the hypothalamic-pituitary-adrenal (HPA) axis and causes elevations in the levels of glucocorticoids (GC) from the adrenal glands. Increasing evidence has demonstrated that prolonged exposure to high GC levels can lead to oxidative stress, calcium deregulation, mitochondrial dysfunction and apoptosis in a number of cell types. However, melatonin, via its antioxidant activity, exhibits a neuroprotective effect against oxidative stress-induced cell death. Therefore, in the present study, we explored the protective effect of melatonin in GC-induced toxicity in human neuroblastoma SH-SY5Y cells. Cellular treatment with the toxically high doses of the synthetic GC receptor agonist, dexamethasone (DEX) elicited marked decreases in the levels of glutathione and increases in ROS production, lipid peroxidation and cell death. DEX toxicity also induced increases in the levels of cytosolic calcium and mitochondrial fusion proteins (Mfn1 and Opa1) but decreases in the levels of mitochondrial fission proteins (Fis1 and Drp1). Mitochondrial damage was observed in large proportions of the DEX-treated cells. Pretreatment of the cells with melatonin substantially prevented the DEX-induced toxicity. These results suggest that melatonin might exert protective effects against oxidative stress, cytosolic calcium overload and mitochondrial damage in DEX-induced neurotoxicity
Correlated decay of triplet excitations in the Shastry-Sutherland compound SrCu(BO)
The temperature dependence of the gapped triplet excitations (triplons) in
the 2D Shastry-Sutherland quantum magnet SrCu(BO) is studied by
means of inelastic neutron scattering. The excitation amplitude rapidly
decreases as a function of temperature while the integrated spectral weight can
be explained by an isolated dimer model up to 10~K. Analyzing this anomalous
spectral line-shape in terms of damped harmonic oscillators shows that the
observed damping is due to a two-component process: one component remains sharp
and resolution limited while the second broadens. We explain the underlying
mechanism through a simple yet quantitatively accurate model of correlated
decay of triplons: an excited triplon is long-lived if no thermally populated
triplons are near-by but decays quickly if there are. The phenomenon is a
direct consequence of frustration induced triplon localization in the
Shastry--Sutherland lattice.Comment: 5 pages, 4 figure
Isolation, Modification and Characterization of Tiger-Nut, Maize, Cassava and Potato Starch
Four different sources of starchy foods were used for the isolation of starch using commercially cheap and readily available chemical-hypo (3.5 % active Chlorine). The isolated starch was modified through NaIO4 oxidation under mild reaction conditions. Carbonyl functional group test was employed for confirmation of the success of oxidation. FT-IR and Scanning Electron Microscopy (SEM) were used for functional group identification and morphological examination of both modified and native samples to further confirm the success of modification. The appearance of the carbonyl band at 1747-1746 cm-1 and 1647 – 1637 cm-1 indicated the successful synthesis of oxidized starch. Proximate results showed that the isolated starches were rich in mineral content: 0.25-2.13; crude fibre: 0.85-3.31; fat: 0.23-0.28 and energy: 1331-1410. The study showed that commercial hypo could be a useful replacement for metabisulphite for starch isolation without side effects on starch properties. SEM images showed that morphological architecture of granules was not destroyed during surface functionalization. Characteristic and nutritional features of the oxidized starch showed that it could find useful applications in food and pharmaceutical industries
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