1,175 research outputs found
Analysis and identification of possible automation approaches for embedded systems design flows
Sophisticated and high performance embedded systems are present in an increasing number of application domains. In this context, formal-based design methods have been studied to make the development process robust and scalable. Models of computation (MoC) allows the modeling of an application at a high abstraction level by using a formal base. This enables analysis before the application moves to the implementation phase. Different tools and frameworks supporting MoCs have been developed. Some of them can simulate the models and also verify their functionality and feasibility before the next design steps. In view of this, we present a novel method for analysis and identification of possible automation approaches applicable to embedded systems design flow supported by formal models of computation. A comprehensive case study shows the potential and applicability of our method11212
Oxygen and hydrogen isotope fractionation in serpentine–water and talc–water systems from 250 to 450°C, 50 MPa
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 73 (2009): 6789-6804, doi:10.1016/j.gca.2009.07.036.Oxygen and hydrogen isotope fractionation factors in the talc-water and serpentine-water systems
have been determined by laboratory experiment from 250 to 450°C at 50 MPa using the partial
exchange technique. Talc was synthesized from brucite + quartz, resulting in nearly 100%
exchange during reaction at 350 and 450°C. For serpentine, D-H exchange was much more rapid
than 18O-16O exchange when natural chrysotile fibers were employed in the initial charge. In
experiments with lizardite as the starting charge, recrystallization to chrysotile enhanced the rate
of 18O-16O exchange with the coexisting aqueous phase.This work was supported by NSF Grants OCE-9313980 to the Woods Hole Oceanographic Institution and OCE-9820287 to Bridgewater State College (BSC)
Influence of severe plastic deformation on the precipitation hardening of a FeSiTi steel
The combined strengthening effects of grain refinement and high precipitated
volume fraction (~6at.%) on the mechanical properties of FeSiTi alloy subjected
to SPD processing prior to aging treatment were investigated by atom probe
tomography and scanning transmission electron microscopy. It was shown that the
refinement of the microstructure affects the precipitation kinetics and the
spatial distribution of the secondary hardening intermetallic phase, which was
observed to nucleate heterogeneously on dislocations and sub-grain boundaries.
It was revealed that alloys successively subjected to these two strengthening
mechanisms exhibit a lower increase in mechanical strength than a simple
estimation based on the summation of the two individual strengthening
mechanisms
Revealing power dynamics and staging conflicts in agricultural system transitions : Case studies of innovation platforms in New Zealand
Innovation platforms (IPs) that support agricultural innovation to enable transition processes towards more sustainable agriculture provide a space where conflicts of interest among actors in the existing agricultural system (the so called incumbent regime) may play out. Sometimes these conflicts over how actors will benefit from an action are not revealed until actors are brought together. However, a barrier to change occurs when IP actors use their existing power to mobilise resources to influence if and how individual and collective interests are aligned. In the context of agricultural innovation and transitions, this paper uses the power in transitions framework (Avelino and Wittmayer, 2016), along with analytical perspectives on conflicts and role perceptions, to understand how consciously staging or revealing conflicts of interest among IP actors changed role perceptions and power relations among these actors. The paper explores this topic in two IPs addressing agricultural production and sustainability challenges in New Zealand's agricultural sector. Conflicts were staged in IPs when one group of actors mobilised resources that enabled them to move existing power relations from one-sided, to synergistic or a mutual dependency. This enabled conflicts to be acknowledged and solved. In contrast, conflicts were not staged when actors mobilised resources to maintain antagonostic power relations. Our cases demontrate that staging conflicts to change actors' role perceptions is an important intermediary step to forming new power relations in the agricultural system. Our findings highlight the need for IP theory to conceptualise power relations in IPs as context specific, dynamic and a force shaping outcomes, rather than solely a force exerted by actors in the incumbent regime over IP actors.</p
Effects of acute fatigue on the volitional and magnetically-evoked electromechanical delay of the knee flexors in males and females
Neuromuscular performance capabilities, including those measured by evoked responses, may be adversely affected by fatigue; however, the capability of the neuromuscular system to initiate muscle force rapidly under these circumstances is yet to be established. Sex-differences in the acute responses of neuromuscular performance to exercise stress may be linked to evidence that females are much more vulnerable to ACL injury than males. Optimal functioning of the knee flexors is paramount to the dynamic stabilisation of the knee joint, therefore the aim of this investigation was to examine the effects of acute maximal intensity fatiguing exercise on the voluntary and magnetically-evoked electromechanical delay in the knee flexors of males and females. Knee flexor volitional and magnetically-evoked neuromuscular performance was assessed in seven male and nine females prior to and immediately after: (i) an intervention condition comprising a fatigue trial of 30-seconds maximal static exercise of the knee flexors, (ii) a control condition consisting of no exercise. The results showed that the fatigue intervention was associated with a substantive reduction in volitional peak force (PFV) that was greater in males compared to females (15.0%, 10.2%, respectively, p < 0.01) and impairment to volitional electromechanical delay (EMDV) in females exclusively (19.3%, p < 0.05). Similar improvements in magnetically-evoked electromechanical delay in males and females following fatigue (21%, p < 0.001), however, may suggest a vital facilitatory mechanism to overcome the effects of impaired voluntary capabilities, and a faster neuromuscular response that can be deployed during critical times to protect the joint system
Two methods for assessment of choline status in a randomized crossover study with varying dietary choline intake in people: Isotope dilution MS of plasma and in vivo single-voxel magnetic resonance spectroscopy of liver
Background: Choline deficiency has numerous negative health consequences; although the preponderance of the US population consumes less than the recommended Adequate Intake (AI), clinical assessment of choline status is difficult. Further, several pathways involved in primary metabolism of choline are estrogen-sensitive and the AI for premenopausal women is lower than that for men. Objectives: We sought to determine whether in vivo magnetic resonance spectroscopy (MRS) of liver and/or isotope-dilution MS of plasma could identify biomarkers reflective of choline intake (preregistered primary outcomes 1 and 2, secondary outcome 1). Determination of whether biomarker concentrations showed sex dependence was a post hoc outcome. This substudy is a component of a larger project to identify a clinically useful biomarker panel for assessment of choline status. Methods: In a double-blind, randomized, crossover trial, people consumed 3 diets, representative of ∼100%, ∼50%, and ∼25% of the choline AI, for 2-wk periods. We measured the concentrations of choline and several metabolites using 1H single-voxel MRS of liver in vivo and using 2H-labeled isotope dilution MS of several choline metabolites in extracted plasma. Results: Plasma concentrations of 2H9-choline, unlabeled betaine, and 2H9-betaine, and the isotopic enrichment ratio (IER) of betaine showed highly significant between-diet effects (q < 0.0001), with unlabeled betaine concentration decreasing 32% from highest to lowest choline intake. Phosphatidylcholine IER was marginally significant (q = 0.03). Unlabeled phosphatidylcholine plasma concentrations did not show between-diet effects (q = 0.34). 2H9 (trimethyl)-phosphatidylcholine plasma concentrations (q = 0.07) and MRS-measured total soluble choline species liver concentrations (q = 0.07) showed evidence of between-diet effects but this was not statistically significant. Conclusions: Although MRS is a more direct measure of choline status, variable spectral quality limited interpretation. MS analysis of plasma showed clear correlation of plasma betaine concentration, but not plasma phosphatidylcholine concentration, with dietary choline intake. Plasma betaine concentrations also correlate with sex status (premenopausal women, postmenopausal women, men)
Nonconcave entropies in multifractals and the thermodynamic formalism
We discuss a subtlety involved in the calculation of multifractal spectra
when these are expressed as Legendre-Fenchel transforms of functions analogous
to free energy functions. We show that the Legendre-Fenchel transform of a free
energy function yields the correct multifractal spectrum only when the latter
is wholly concave. If the spectrum has no definite concavity, then the
transform yields the concave envelope of the spectrum rather than the spectrum
itself. Some mathematical and physical examples are given to illustrate this
result, which lies at the root of the nonequivalence of the microcanonical and
canonical ensembles. On a more positive note, we also show that the
impossibility of expressing nonconcave multifractal spectra through
Legendre-Fenchel transforms of free energies can be circumvented with the help
of a generalized free energy function, which relates to a recently introduced
generalized canonical ensemble. Analogies with the calculation of rate
functions in large deviation theory are finally discussed.Comment: 9 pages, revtex4, 3 figures. Changes in v2: sections added on
applications plus many new references; contains an addendum not contained in
published versio
L\'{e}vy scaling: the Diffusion Entropy Analysis applied to DNA sequences
We address the problem of the statistical analysis of a time series generated
by complex dynamics with a new method: the Diffusion Entropy Analysis (DEA)
(Fractals, {\bf 9}, 193 (2001)). This method is based on the evaluation of the
Shannon entropy of the diffusion process generated by the time series imagined
as a physical source of fluctuations, rather than on the measurement of the
variance of this diffusion process, as done with the traditional methods. We
compare the DEA to the traditional methods of scaling detection and we prove
that the DEA is the only method that always yields the correct scaling value,
if the scaling condition applies. Furthermore, DEA detects the real scaling of
a time series without requiring any form of de-trending. We show that the joint
use of DEA and variance method allows to assess whether a time series is
characterized by L\'{e}vy or Gauss statistics. We apply the DEA to the study of
DNA sequences, and we prove that their large-time scales are characterized by
L\'{e}vy statistics, regardless of whether they are coding or non-coding
sequences. We show that the DEA is a reliable technique and, at the same time,
we use it to confirm the validity of the dynamic approach to the DNA sequences,
proposed in earlier work.Comment: 24 pages, 9 figure
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