735 research outputs found
Multifractal properties of elementary cellular automata in a discrete wavelet approach of MF-DFA
In 2005, Nagler and Claussen (Phys. Rev. E 71 (2005) 067103) investigated the
time series of the elementary cellular automata (ECA) for possible
(multi)fractal behavior. They eliminated the polynomial background at^b through
the direct fitting of the polynomial coefficients a and b. We here reconsider
their work eliminating the polynomial trend by means of the multifractal-based
detrended fluctuation analysis (MF-DFA) in which the wavelet multiresolution
property is employed to filter out the trend in a more speedy way than the
direct polynomial fitting and also with respect to the wavelet transform
modulus maxima (WTMM) procedure. In the algorithm, the discrete fast wavelet
transform is used to calculate the trend as a local feature that enters the
so-called details signal. We illustrate our result for three representative ECA
rules: 90, 105, and 150. We confirm their multifractal behavior and provide our
results for the scaling parametersComment: 8 pages, 5 figures, 21 reference
Multifractal properties of elementary cellular automata in a discrete wavelet approach of MF-DFA
In 2005, Nagler and Claussen (Phys. Rev. E 71 (2005) 067103) investigated the
time series of the elementary cellular automata (ECA) for possible
(multi)fractal behavior. They eliminated the polynomial background at^b through
the direct fitting of the polynomial coefficients a and b. We here reconsider
their work eliminating the polynomial trend by means of the multifractal-based
detrended fluctuation analysis (MF-DFA) in which the wavelet multiresolution
property is employed to filter out the trend in a more speedy way than the
direct polynomial fitting and also with respect to the wavelet transform
modulus maxima (WTMM) procedure. In the algorithm, the discrete fast wavelet
transform is used to calculate the trend as a local feature that enters the
so-called details signal. We illustrate our result for three representative ECA
rules: 90, 105, and 150. We confirm their multifractal behavior and provide our
results for the scaling parametersComment: 8 pages, 5 figures, 21 reference
Towards the Design of Heuristics by Means of Self-Assembly
The current investigations on hyper-heuristics design have sprung up in two
different flavours: heuristics that choose heuristics and heuristics that
generate heuristics. In the latter, the goal is to develop a problem-domain
independent strategy to automatically generate a good performing heuristic for
the problem at hand. This can be done, for example, by automatically selecting
and combining different low-level heuristics into a problem specific and
effective strategy. Hyper-heuristics raise the level of generality on automated
problem solving by attempting to select and/or generate tailored heuristics for
the problem at hand. Some approaches like genetic programming have been
proposed for this. In this paper, we explore an elegant nature-inspired
alternative based on self-assembly construction processes, in which structures
emerge out of local interactions between autonomous components. This idea
arises from previous works in which computational models of self-assembly were
subject to evolutionary design in order to perform the automatic construction
of user-defined structures. Then, the aim of this paper is to present a novel
methodology for the automated design of heuristics by means of self-assembly
Bulk Enthalpy Calculations in the Arc Jet Facility at NASA ARC
The Arc Jet Facilities at NASA Ames Research Center generate test streams with enthalpies ranging from 5 MJ/kg to 25 MJ/kg. The present work describes a rigorous method, based on equilibrium thermodynamics, for calculating the bulk enthalpy of the flow produced in two of these facilities. The motivation for this work is to determine a dimensionally-correct formula for calculating the bulk enthalpy that is at least as accurate as the conventional formulas that are currently used. Unlike previous methods, the new method accounts for the amount of argon that is present in the flow. Comparisons are made with bulk enthalpies computed from an energy balance method. An analysis of primary facility operating parameters and their associated uncertainties is presented in order to further validate the enthalpy calculations reported herein
Emission Spectroscopic Measurements in the Plenum Region of the NASA IHF Arc Jet Facility
A newly designed segment with optical access was installed in the plenum chamber of the 60 MW Interaction Heating arcjet Facility at NASA Ames Research Center. This special segment has ports located off axis, and the optical fibers can be inserted into these ports. The special segment allows for optical examination of the arc-heated flow as it enters the plenum, and thus assists in determining estimates of the thermodynamic state of the inflow to the convergent section of the nozzle. In the present work, optical emission measurements have been made in VIS-NIR region (wavelengths between 500 nm to 900 nm) for two settings of the arc heater - a 6000 A condition (high condition) with the minimum amount of radial injection of cold air in the plenum, and a 3300 A condition (low condition) with significant amount of cold air injection to reduce the enthalpy of the arc-heated stream. The results presented here were obtained using an Acton SP300i spectrometer coupled to a Princeton Instruments PI-max intensified camera. In addition to the optical emission measurements, computations were performed for the flow in the plenum and radiation along lines of sight corresponding to the optical ports. Along the centerline, i.e., the longest line of sight across the plenum cross-section, there is good agreement between computations and measurements for the high enthalpy condition, although the off-axis radial profiles show some differences. For the low enthalpy condition, there are significant differences between computations and measurements. The current working hypothesis is that the computational model does not capture details of the mixing process in the plenum
Mycobacteriosis in a Bull Trout from Hungry Horse Reservoir, Montana
An angler-caught bull trout (Salvelinus confluentus) from Hungry Horse Reservoir, MT with noticeably poor condition was examined to reveal liver nodules. Further investigation discovered acid-fast bacteria present in these granulomas making this a unique finding requiring further diagnostics. Molecular diagnostics revealed the infectious agent to be Mycobacterium fortuitum. This is a range and species expansion for this pathogen in fish. Further examination of additional fish from this water body did not reveal cases similar to this one, allowing for the possibility of this being a lone occurrence
A declining major merger fraction with redshift in the local Universe from the largest-yet catalog of major and minor mergers in SDSS
It is difficult to accurately identify galaxy mergers and it is an even
larger challenge to classify them by their mass ratio or merger stage. In
previous work we used a suite of simulated mergers to create a classification
technique that uses linear discriminant analysis (LDA) to identify major and
minor mergers. Here, we apply this technique to 1.3 million galaxies from the
SDSS DR16 photometric catalog and present the probability that each galaxy is a
major or minor merger, splitting the classifications by merger stages (early,
late, post-coalescence). We present publicly-available imaging predictor values
and all of the above classifications for one of the largest-yet samples of
galaxies. We measure the major and minor merger fraction ()
and build a mass-complete sample of galaxies, which we bin as a function of
stellar mass and redshift. For the major mergers, we find a positive slope of
with stellar mass and negative slope of
with redshift between stellar masses of
and redshifts of . We are able to reproduce an artificial
positive slope of the major merger fraction with redshift when we do not bin
for mass or craft a complete sample, demonstrating the importance of mass
completeness and mass binning. We determine that the positive trend of the
major merger fraction with stellar mass is consistent with a hierarchical
assembly scenario. The negative trend with redshift requires that an additional
assembly mechanism, such as baryonic feedback, dominates in the local Universe.Comment: 29 pages, 22 figures, see figures 16 and 17 for a summary of the
findings, accepted to MNRA
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Digital manufacturing on a shoestring: Low cost digital solutions for SMEs
One of the key findings in a number of recent studies has been that small and medium sized manufacturers (SMEs) have been slow in adopting digital solutions within their organisations. Cost is understood to be one of the key barriers to adoption. Digital Manufacturing on a Shoestring is an approach to increasing the digital capabilities of SMEs via a series of low cost solutions. The programme proposes using off-the-shelf, (possibly non-industrial) components and software to address a company’s (digital) solution needs, adding capabilities one step at a time with minimal a priori infrastructure required. This paper will introduce the Digital Manufacturing on a Shoestring programme as a whole and demonstrate the way in which it addresses the need for low cost digital solutions for SME Manufacturers. It will discuss challenges associated with integrating low cost technologies into industrial solutions and the style of IT architectures best suited for integrating such solutions into industrial environments
Dibenzothiophene hydrodesulfurization over P-CoMo on sol-gel alumina modified by La addition. Effect of rare-earth content
articuloAlumina-lanthana (La at 1, 3, or 5 wt%) supports were prepared by sol-gel from Al alkoxide sol where La(NO 3 ) 3 was added. Annealed (550 °C) xerogels were characterized by N 2 physisorption, thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy- energy dispersive spectroscopy (SEM-EDS), CO 2 -adsorption studied in IR region, Raman and ultraviolet-vis (UV-vis) spectroscopies. The texture of amorphous binary matrices of high La dispersion was adequate to applications in catalysts for middle distillates hydrodesulfurization (HDS). Generally, the amount and strength of surface basic sites increased with La content in solids. Mo (at 2.8 at. nm −2 ) and Co (at Co/(Co+Mo) = 0.3) were deposited over carriers by one-pot simultaneous impregnation in the presence of PO 4 3− (P 2 O 5 /(NiO+MoO 3 ) = 0.2 mass ratio). Calcined (400 °C) Co-Mo-P impregnated precursors had decreased basicity as to that of corresponding carriers, suggesting strong La-deposited species interaction. As La content in carriers increased Mo=O Raman stretching vibrations shifted to lower wave-numbers (949 to 935 cm −1 ) suggesting octahedral molybdates coordination change to tetrahedral. Although La at the lowest concentration (1 wt%) enhanced dibenzothiophene, HDS (~38% higher as to the Al 2 O 3 -supported formulation) desulfurization was significantly diminished at augmented content. Presence of hardly sulfidable tetrahedral Mo originated during impregnation at basic conditions in pores of La-modified carriers seemed to dictate observed behavior. Rare earth content in formulations enhanced selectivity to biphenyl.: J. Escobar acknowledges financial support from IMP (Y.00105) and SENER-CONACYTHidrocarburos (115086) fund
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Characterization of Intact Proviruses in Blood and Lymph Node from HIV-Infected Individuals Undergoing Analytical Treatment Interruption.
The role of lymphoid tissue as a potential source of HIV-1 rebound following interruption of antiretroviral therapy (ART) is uncertain. To address this issue, we compared the latent viruses obtained from CD4+ T cells in peripheral blood and lymph nodes to viruses emerging during treatment interruption. Latent viruses were characterized by sequencing near-full-length (NFL) proviral DNA and env from viral outgrowth assays (VOAs). Five HIV-1-infected individuals on ART were studied, four of whom participated in a clinical trial of a TLR9 agonist that included an analytical treatment interruption. We found that 98% of intact or replication-competent clonal sequences overlapped between blood and lymph node. In contrast, there was no overlap between 205 latent reservoir and 125 rebound sequences in the four individuals who underwent treatment interruption. However, rebound viruses could be accounted for by recombination. The data suggest that CD4+ T cells carrying latent viruses circulate between blood and lymphoid tissues in individuals on ART and support the idea that recombination may play a role in the emergence of rebound viremia.IMPORTANCE HIV-1 persists as a latent infection in CD4+ T cells that can be found in lymphoid tissues in infected individuals during ART. However, the importance of this tissue reservoir and its contribution to viral rebound upon ART interruption are not clear. In this study, we sought to compare latent HIV-1 from blood and lymph node CD4+ T cells from five HIV-1-infected individuals. Further, we analyzed the contribution of lymph node viruses to viral rebound. We observed that the frequencies of intact proviruses were the same in blood and lymph node. Moreover, expanded clones of T cells bearing identical proviruses were found in blood and lymph node. These latent reservoir sequences did not appear to be the direct origin of rebound virus. Instead, latent proviruses were found to contribute to the rebound compartment by recombination
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