scholarly journals Analysis of modern observations of meteor showers based on PTM methods

2021 ◽  
Vol 2103 (1) ◽  
pp. 012024
Author(s):  
A A Sharafutdinova ◽  
A O Andreev ◽  
Y A Nefedyev ◽  
R Hudec ◽  
N Y Demina
Keyword(s):  
Distribution Density ◽  
Data Bank ◽  
Meteor Shower ◽  
New Method ◽  
Radar Observations ◽  
Tomography Method ◽  
Celestial Sphere ◽  
First Time ◽  
Sporadic Meteors ◽  
Meteor Particle

Abstract The work is focused on the analysis of modern observations of meteoroids included in the data bank formed by both professional researchers and amateur astronomers. Based on the modern physical theory of meteoroids (PTM), a new method for analyzing measurements developed, which provides the accuracy comparable with the results of radar observations. Due to the fact that the accuracy of the new method for analyzing meteoroids observations has increased significantly, it became possible to process observations of the Perseid and Leonid showers over a period of 120 years. The use of PTM made it possible for the first time to explain the distribution of meteor echo signals observed at an altitude of 2 MHz, at which the upper part of this distribution refers to an altitude of 140 km. In the process of work, a database of orbital characteristics of meteoroids was created. A method has been developed for modeling the probability of hitting a certain area of a meteor particle with a mass greater than a certain specified value and determining the density of a meteor shower from radio observations as well as a new “tomography” method for calculating the density distribution of sporadic meteors in the sky using radar observations of meteors at the same station with a goniometer. The method allows calculating the density of a meteor shower on the celestial sphere with an angular resolution of 2°. The use of these methods served as a proof that the distribution density of meteoroid showers on the celestial sphere has two planes of symmetry: the first coincides with the plane of the ecliptic, passing through the poles of the Earth, the other one is perpendicular to the plane of the ecliptic.

Application of an Improved Colored Petri Net Modeling Method in Certain Missile Training System

2015 ◽  
Vol 742 ◽  
pp. 330-334
Author(s):  
Chun Jian Wang ◽  
Wei Yue ◽  
Hai Yan Ji
Keyword(s):  
Complex System ◽  
Petri Net ◽  
Time Use ◽  
Training System ◽  
New Method ◽  
Mathematics Model ◽  
Research Approach ◽  
Complex Environments ◽  
Training Simulator ◽  
First Time

In allusion to the need of analyzing complex system, we have proposed a method named multi-grade color Petri net. We for the first time use this new method to analyze a missile training simulator system. This model can accurately reflect the complex environments of the system and avoid the difficulty occurring often in developing accurate mathematics model by using classical research approach.

Attitudes and Choice of Contraceptive

1979 ◽  
Vol 44 (3_suppl) ◽  
pp. 1243-1246 ◽  
Author(s):  
A. E. Reading ◽  
C. Harris ◽  
J. R. Newton
Keyword(s):  
Comparison Group ◽  
Termination Of Pregnancy ◽  
New Method ◽  
Contraceptive Methods ◽  
High Concordance ◽  
First Time

Attitudes towards contraceptive methods were sampled among 117 women, in their mid-20's, selecting a new method (Pill, IUD, Injectable) and a comparison group of women undergoing termination of pregnancy for the first time. High concordance was found, suggesting women were applying essentially the same standards in making their selection.

scholarly journals AlphaFold at CASP13

2019 ◽  
Vol 35 (22) ◽  
pp. 4862-4865 ◽  
Author(s):  
Mohammed AlQuraishi
Keyword(s):  
Protein Structure ◽  
Protein Sequence ◽  
Structure Prediction ◽  
Computational Prediction ◽  
Data Bank ◽  
Academic Community ◽  
Physical Contact ◽  
Evolutionary Analysis ◽  
History Of ◽  
First Time

Abstract Summary: Computational prediction of protein structure from sequence is broadly viewed as a foundational problem of biochemistry and one of the most difficult challenges in bioinformatics. Once every two years the Critical Assessment of protein Structure Prediction (CASP) experiments are held to assess the state of the art in the field in a blind fashion, by presenting predictor groups with protein sequences whose structures have been solved but have not yet been made publicly available. The first CASP was organized in 1994, and the latest, CASP13, took place last December, when for the first time the industrial laboratory DeepMind entered the competition. DeepMind's entry, AlphaFold, placed first in the Free Modeling (FM) category, which assesses methods on their ability to predict novel protein folds (the Zhang group placed first in the Template-Based Modeling (TBM) category, which assess methods on predicting proteins whose folds are related to ones already in the Protein Data Bank.) DeepMind's success generated significant public interest. Their approach builds on two ideas developed in the academic community during the preceding decade: (i) the use of co-evolutionary analysis to map residue co-variation in protein sequence to physical contact in protein structure, and (ii) the application of deep neural networks to robustly identify patterns in protein sequence and co-evolutionary couplings and convert them into contact maps. In this Letter, we contextualize the significance of DeepMind's entry within the broader history of CASP, relate AlphaFold's methodological advances to prior work, and speculate on the future of this important problem.

scholarly journals MOF Decomposition and Introduction of Repairable Defects Using a Photodegradable Strut

2018 ◽  
Author(s):  
Jingjing Yan ◽  
John MacDonald ◽  
Shawn Burdette
Keyword(s):  
Drug Delivery ◽  
Porous Materials ◽  
New Method ◽  
Innovative Approach ◽  
Partial Decomposition ◽  
Multiple Defects ◽  
Potential Applications ◽  
Defect Repair ◽  
First Time ◽  
Interesting Area

Utilizing a photolabile ligand as MOF strut can make a framework undergo full or partial decomposition upon irradiation. For the first time, a nitrophenylacetate derivative has been incorporated into MOF as a backbone linker via PLSE method. The photo-induced decarboxylation of the NPDAC-MOF represents a novel way of degrading a MOF, which provides an innovative approach to formulating photoresponsive porous materials with potential applications in molecular release and drug delivery. When photoactive linker is mixed with non-photolabile linker via partial PLSE, the MOF structure can be retained after irradiation, but with the introduction of multiple defects, offering a new method to create vacancies in MOFs. Defect repair can be achieved by treatment with replacement ligands, the scope of which is an interesting area for developing customizable MOF contents.<br>

scholarly journals New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+) as a Green Solid Catalyst

2016 ◽  
Vol 11 (2) ◽  
pp. 151 ◽  
Author(s):  
Lahouaria Medjdoub ◽  
Belbachir Mohammed
Keyword(s):  
Nucleophilic Substitution ◽  
Room Temperature ◽  
Montmorillonite Clay ◽  
New Method ◽  
Solid Catalyst ◽  
H Nmr ◽  
Flight Mass Spectrometry ◽  
Crystalline Product ◽  
First Time ◽  
C Nmr

<p>Nucleophilic substitution on hexachlorocyclotriphosphazene (HCCTP) with allylamine in order to give hexa(allylamino)cyclotriphosphazene (HACTP)  is performed for the first time under mild conditions by using diethylether as solvent to replace benzene which is very toxic. The reaction time is reduced to half and also performed at room temperature but especially in the presence of an eco-catalyst called Maghnite-H<sup>+</sup>. This catalyst has a significant role in the industrial scale. In fact, the use of Maghnite is preferred for its many advantages: a very low purchase price compared to other catalysts, the easy removal of the reaction mixture. Then, Maghnite-H<sup>+</sup> is became an excellent catalyst for many chemical reactions. The structure of HACTP synthesized in the presence of Maghnite-H<sup>+</sup> to 5% by weight is confirmed by <sup>1</sup>H-NMR, <sup>13</sup>C-NMR, <sup>31</sup>P-NMR (Nuclear magnetic resonance) and FTIR (Fourier Transform Infrared spectroscopy). MALDI-TOF (Matrix-Assisted Laser Desorption/Ionisation-time-of-flight mass spectrometry) is used to establish the molecular weight of HACTP which is 471 g/mol. DSC (Differential Scanning Calorimetery) and TGA (Thermogravimetric Analysis) show that HACTP is a crystalline product with a melting point of 88 °C. It is reactive after melting but is degraded from 230 °C. Copyright © 2016 BCREC GROUP. All rights reserved</p><p><em>Received: 28<sup>th</sup> September 2015; Revised: 5<sup>th</sup> December 2015; Accepted: 4<sup>th</sup> January 2016</em></p><p><strong>How to Cite</strong>: Medjdoub, L., Mohammed, B. (2016). New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+) as a Green Solid Catalyst. <em>Bulletin of Chemical Reaction Engineering &amp; Catalysis</em>, 11 (2): 151-160 (doi:10.9767/bcrec.11.2.541.151-160)</p><p><strong>Permalink/DOI:</strong> http://dx.doi.org/10.9767/bcrec.11.2.541.151-160</p>

scholarly journals A new method to derive middle atmospheric temperature profiles using a combination of Rayleigh lidar and O<sub>2</sub> airglow temperatures measurements

2012 ◽  
Vol 30 (1) ◽  
pp. 27-32 ◽  
Author(s):  
A. Taori ◽  
A. Jayaraman ◽  
K. Raghunath ◽  
V. Kamalakar
Keyword(s):  
Temperature Profile ◽  
Atmospheric Temperature ◽  
New Method ◽  
Temperature Profiles ◽  
Vertical Temperature ◽  
Lidar System ◽  
Mesospheric Temperature ◽  
Simultaneous Measurements ◽  
Rayleigh Lidar ◽  
First Time

Abstract. The vertical temperature profiles in a typical Rayleigh lidar system depends on the backscatter photon counts and the CIRA-86 model inputs. For the first time, we show that, by making simultaneous measurements of Rayleigh lidar and upper mesospheric O2 temperatures, the lidar capability can be enhanced to obtain mesospheric temperature profile up to about 95 km altitudes. The obtained results are compared with instantaneous space-borne SABER measurements for a validation.

scholarly journals 4D Bragg Edge Tomography of Directional Ice Templated Graphite Electrodes

2020 ◽  
Vol 6 (12) ◽  
pp. 136
Author(s):  
Ralf F. Ziesche ◽  
Anton S. Tremsin ◽  
Chun Huang ◽  
Chun Tan ◽  
Patrick S. Grant ◽  
...  
Keyword(s):  
Li Ion Battery ◽  
Graphite Electrodes ◽  
Neutron Spallation Source ◽  
Spallation Source ◽  
Li Ion ◽  
Tomography Method ◽  
First Time ◽  
Pulsed Neutron ◽  
Tomography Data ◽  
Insight Into

Bragg edge tomography was carried out on novel, ultra-thick, directional ice templated graphite electrodes for Li-ion battery cells to visualise the distribution of graphite and stable lithiation phases, namely LiC12 and LiC6. The four-dimensional Bragg edge, wavelength-resolved neutron tomography technique allowed the investigation of the crystallographic lithiation states and comparison with the electrode state of charge. The tomographic imaging technique provided insight into the crystallographic changes during de-/lithiation over the electrode thickness by mapping the attenuation curves and Bragg edge parameters with a spatial resolution of approximately 300 µm. This feasibility study was performed on the IMAT beamline at the ISIS pulsed neutron spallation source, UK, and was the first time the 4D Bragg edge tomography method was applied to Li-ion battery electrodes. The utility of the technique was further enhanced by correlation with corresponding X-ray tomography data obtained at the Diamond Light Source, UK.

Observations of Meteors using an over-the-horizon Radar

1989 ◽  
Vol 8 (1) ◽  
pp. 88-93 ◽  
Author(s):  
R. M. Thomas ◽  
D. J. Netherway
Keyword(s):  
Signal Processing ◽  
High Frequency ◽  
Meteor Shower ◽  
Upper Atmosphere ◽  
High Frequency Band ◽  
Meteor Detection ◽  
Signal Environment ◽  
Frequency Management ◽  
Sporadic Meteors ◽  
Selection Of

AbstractWhen metre wavelength radars were first operated in the 1940s, echoes were obtained which could be attributed to backscatter from ionised trains produced by the ablation of meteroids in the upper atmosphere at altitudes near 100 km. Modern over-the-horizon skywave radars operating in the HF (High Frequency) band employ digital techniques for both radar control and signal processing and are aided by frequency management subsystems for the selection of appropriate frequencies for meteor detection based on real-time monitoring of the HF signal environment.This paper describes the results of using such a radar for meteor observations. We report the detection of the Eta Aquarid meteor shower and demonstrate that a large increase in the echo rate due to sporadic meteors is obtained as frequencies are reduced below 15 MHz and the underdense echo ceiling rises in altitude. Finally, we present preliminary observations of highly Doppler shifted echoes which travel at meteoric velocities and which we identify as meteor ‘head echoes’.

scholarly journals Deep-water decapod crustaceans studied with a remotely operated vehicle (ROV) in the Marquesas Islands, French Polynesia (Crustacea: Decapoda)

Zootaxa ◽  
2012 ◽  
Vol 3550 (1) ◽  
pp. 43 ◽  
Author(s):  
JOSEPH POUPIN ◽  
LAURE CORBARI ◽  
THIERRY PÉREZ ◽  
PIERRE CHEVALDONNÉ
Keyword(s):  
Distribution Density ◽  
French Polynesia ◽  
Careful Examination ◽  
Decapod Crustaceans ◽  
Remotely Operated Vehicle ◽  
Marquesas Islands ◽  
And Behavior ◽  
First Time ◽  
Made In

Decapod crustaceans were studied in the Marquesas Islands, French Polynesia, between 50–550 m by using a remotelyoperated vehicle (ROV) equipped with high resolution cameras and an articulated arm. Careful examination of videos andphotographs combined with previous inventories made in the area with conventional gears allowed the identification of30 species, including 20 species-level determinations. Species identified belong to shrimps (Penaeoidea, Stenopodidea,and Caridea), lobsters (Astacidea and Achelata), anomurans (Galatheoidea and Paguroidea), and brachyuran crabs(Dromioidea, Homolodromioidea, Raninoidea, Leucosioidea, Majoidea, Parthenopoidea, Portunoidea, and Trapezioidea).Most of these species were observed and photographed in situ for the first time. A discussion is given on the geographic distribution, density, ecology, and behavior.

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