4,609 research outputs found
Studying the Effect of Adding Aleppo Pylon to the Properties of Insulating and Accumulation of Polyvinyl Chloride Films
This research presents a study of the effect of adding natural and modified Aleppo Pylon (Syrian clay) in different proportions to the properties of polymeric films prepared from poly vinyl chlorid (PVC) polymer and dried at three different drying degrees (60oC, 100oC, 150oC). The clay surface was changed from hydrophilic to hydrophobic by treating the surface with quaternary alkyl ammonium salts. Both types of Aleppo Pylone were added to the polymer by weight (0%, 2.5%, 5%, 7.5%, 10%), and the polymeric films were prepared by way of mixing well of PVC polymer and clay. The mixing technique used hexanol as a solvent. The clay was mixed with the polymer at 150 Co temperature using a magnetic stirrer. The effect of adding natural and modified Aleppo Pylon to the properties of water absorption ratio, moisture content, migration of components in moderate, acidic and alkaline aqueous solutions, thermal stability and air permeability of polymeric films prepared from PVC polymer and clay with different drying degrees was studied and compared with them, in order to reach an improved PVC that can be used in the field of packaging
Impact of biochar and arbuscular mycorrhizal inoculation on root colonization and selected soil chemical properties in south western Nigeria
The use of biochar and arbuscular mycorrhizal fungi (AMF) provide many opportunities for soil improvement, it is, therefore, important to understand their impact on soil and plant development so as to optimally exploit their potentials. Screenhouse experiment was conducted to evaluate the impact of biochar application and arbuscular mycorrhizal (AM) inoculation on root colonization and selected soil chemical properties. The experiment was laid out in a 2×5×2 factorial, fitted into a completely randomized design with three replications. The factors included tomato genotypes (Ex-Lafia and Ex-Lokoja), biochar application rates (0, 5, 10, 15, and 20 t ha-1) and AMF (with and without AMF). Data were subjected to analysis of variance and significant means were separated using Duncan’s Multiple Range Test (p<0.05). The results showed that AM inoculation significantly (p<0.05) increased root colonization (51.33%) when compared with non mycorrhizal plants (10.17%). However, no significant differences were observed in soil pH, organic carbon and available P between mycorrhizal and non mycorrhizal plants. On the other hand, amendment with the 20t ha-1 of biochar recorded significantly (p<0.05) higher values of AM root colonization (46.25%), soil pH (7.05) and available P (13.93 mg kg-1) when compared to other biochar rates though comparable with 15 t ha-1 in soil pH (7.05) and available P (12.26 mg kg-1). It is therefore concluded that AM inoculation in biochar-amended soil improved root colonization while biochar application enhances root colonization, soil pH and available P.Keywords: Biochar, AM inoculation, soil chemical properties
Korelasi antara Gula Darah 2 Jam Postprandial Danhba1c di Laboratorium Klinik Graha Spesialis RSMH Palembang
Pemeriksaan gula darah merupakan pemeriksaan yang dilakukan untuk menegakkan diagnosis diabetes melitus. Hasil pemeriksaan gula darah pasien tidak cukup menggambarkan kondisi gula darah pasien, sehingga diperlukan pemeriksaan lain dengan menilai kadar HbA1c. Tujuan penelitian ini adalah untuk menganalisis korelasi antara kadar gula darah 2 jam postprandial dan nilai HbA1c.Jenis penelitian yang dilakukan adalah observasional analitik dengan desain cross sectional. Populasi penelitian adalah pasien yang melakukan pemeriksaan gula darah di Laboratorium Klinik Graha Spesialis RSMH Palembang. Dengan metode purposive sampling, diperoleh 121 orang sampel penelitian. Diperoleh kadar gula darah 2 jam postprandial tidak normal sebanyak 65,3% dan normal sebanyak 34,7%. Usia terbanyak subjek penelitian dengan kadar gula darah 2 jam postprandial tidak normal adalah 15-64 tahun (52,3%). Jenis kelamin terbanyak subjek penelitian dengan kadar gula darah 2 jam postprandial tidak normal adalah laki-laki (34,7%). HbA1c subjek penelitian tidak normal sebanyak 61,2% dan normal 38,8%. Usia terbanyak subjek penelitian dengan nilai HbA1c tidak normal adalah 15-64 tahun (31,5%). Jenis kelamin terbanyak subjek penelitian dengan nilai HbA1c tidak normal adalah laki-laki (31,4%).Perbandingan antara laki-laki dengan perempuan adalah 1,02:1. Rerata simpangan baku kadar gula darah 2 jam postprandial dan nilai HbA1c berturut-turut adalah 191,1 89,3 mg/dl dan7,0 1,98 %. Hasil tabulasi silang antara kadar gula darah 2 jam postprandialdan nilai HbA1c menunjukkan bahwa pada subjek penelitianyang memiliki kadar gula 2 jam postprandial tidak normal, diperoleh sebanyak 15 (12,4%) orang memiliki nilai HbA1c normal dan 64 (52,9%) orang memiliki nilai HbA1c tidak normal. Terdapat korelasi yang kuat antara kadar gula darah 2 jam postprandialdan nilai HbA1c (r=0,638; p=0,0005)
Chaos and Noise in a Truncated Toda Potential
Results are reported from a numerical investigation of orbits in a truncated
Toda potential which is perturbed by weak friction and noise. Two significant
conclusions are shown to emerge: (1) Despite other nontrivial behaviour,
configuration, velocity, and energy space moments associated with these
perturbations exhibit a simple scaling in the amplitude of the friction and
noise. (2) Even very weak friction and noise can induce an extrinsic diffusion
through cantori on a time scale much shorter than that associated with
intrinsic diffusion in the unperturbed system.Comment: 10 pages uuencoded PostScript (figures included), (A trivial
mathematical error leading to an erroneous conclusion is corrected
Observation of Individual Josephson Vortices in YBCO Bicrystal Grain-boundary Junctions
The response of YBCO bicrystal grain-boundary junctions to small dc magnetic
fields (0 - 10 Oe) has been probed with a low-power microwave (rf) signal of
4.4 GHz in a microwave-resonator setup. Peaks in the microwave loss at certain
dc magnetic fields are observed that result from individual Josephson vortices
penetrating into the grain-boundary junctions under study. The system is
modeled as a long Josephson junction described by the sine-Gordon equation with
the appropriate boundary conditions. Excellent quantitative agreement between
the experimental data and the model has been obtained. Hysteresis effect of dc
magnetic field is also studied and the results of measurement and calculation
are compared.Comment: 11 pages, 4 figure
Image Signal Processor parameter tuning with surrogate-assisted Particle Swarm Optimization
International audienceEvolutionary algorithms (EA) are developed and compared based on well defined benchmark problems, but their application to real-world problems is still challenging. In image processing, EA have been used to tune a particular image filter or in the design of filters themselves. But nowadays in digital cameras, the image sensor captures a raw image that is then processed by an Image Signal Processor (ISP) where several transformations or filters are sequentially applied in order to enhance the final picture. Each of these steps have several parameters and their tuning require lot of resources that are usually performed by human experts based on metrics to assess the quality of the final image. This can be considered as an expensive black-box optimization problem with many parameters and many quality metrics. In this paper, we investigate the use of EA in the context of ISP parameter tuning with the aim of raw image enhancement
Robustness of Cosmological Simulations I: Large Scale Structure
The gravitationally-driven evolution of cold dark matter dominates the
formation of structure in the Universe over a wide range of length scales.
While the longest scales can be treated by perturbation theory, a fully
quantitative understanding of nonlinear effects requires the application of
large-scale particle simulation methods. Additionally, precision predictions
for next-generation observations, such as weak gravitational lensing, can only
be obtained from numerical simulations. In this paper, we compare results from
several N-body codes using test problems and a diverse set of diagnostics,
focusing on a medium resolution regime appropriate for studying many
observationally relevant aspects of structure formation. Our conclusions are
that -- despite the use of different algorithms and error-control methodologies
-- overall, the codes yield consistent results. The agreement over a wide range
of scales for the cosmological tests is test-dependent. In the best cases, it
is at the 5% level or better, however, for other cases it can be significantly
larger than 10%. These include the halo mass function at low masses and the
mass power spectrum at small scales. While there exist explanations for most of
the discrepancies, our results point to the need for significant improvement in
N-body errors and their understanding to match the precision of near-future
observations. The simulation results, including halo catalogs, and initial
conditions used, are publicly available.Comment: 32 pages, 53 figures, data from the simulations is available at
http://t8web.lanl.gov/people/heitmann/arxiv, accepted for publication in
ApJS, several minor revisions, reference added, main conclusions unchange
The Halo Mass Function: High-Redshift Evolution and Universality
We study the formation of dark matter halos in the concordance LCDM model
over a wide range of redshifts, from z=20 to the present. Our primary focus is
the halo mass function, a key probe of cosmology. By performing a large suite
of nested-box N-body simulations with careful convergence and error controls
(60 simulations with box sizes from 4 to 256 Mpc/h, we determine the mass
function and its evolution with excellent statistical and systematic errors,
reaching a few percent over most of the considered redshift and mass range.
Across the studied redshifts, the halo mass is probed over 6 orders of
magnitude (10^7 - 10^13.5 M_sun/h). Historically, there has been considerable
variation in the high redshift mass function as obtained by different groups.
We have made a concerted effort to identify and correct possible systematic
errors in computing the mass function at high redshift and to explain the
discrepancies between some of the previous results. We discuss convergence
criteria for the required force resolution, simulation box size, halo mass
range, initial and final redshift, and time stepping. Because of conservative
cuts on the mass range probed by individual boxes, our results are relatively
insensitive to simulation volume, the remaining sensitivity being consistent
with extended Press-Schechter theory. Previously obtained mass function fits
near z=0, when scaled by linear theory, are in good agreement with our results
at all redshifts, although a mild redshift dependence consistent with that
found by Reed and collaborators exists at low redshifts.Comment: 20 pages, 15 figures. Minor changes to the text and figures; results
and conclusions unchange
Chaos in Time Dependent Variational Approximations to Quantum Dynamics
Dynamical chaos has recently been shown to exist in the Gaussian
approximation in quantum mechanics and in the self-consistent mean field
approach to studying the dynamics of quantum fields. In this study, we first
show that any variational approximation to the dynamics of a quantum system
based on the Dirac action principle leads to a classical Hamiltonian dynamics
for the variational parameters. Since this Hamiltonian is generically nonlinear
and nonintegrable, the dynamics thus generated can be chaotic, in distinction
to the exact quantum evolution. We then restrict attention to a system of two
biquadratically coupled quantum oscillators and study two variational schemes,
the leading order large N (four canonical variables) and Hartree (six canonical
variables) approximations. The chaos seen in the approximate dynamics is an
artifact of the approximations: this is demonstrated by the fact that its onset
occurs on the same characteristic time scale as the breakdown of the
approximations when compared to numerical solutions of the time-dependent
Schrodinger equation.Comment: 10 pages (12 figures), RevTeX (plus macro), uses epsf, minor typos
correcte
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