scholarly journals Applications of Machine Learning Algorithms in Processing Terahertz Spectroscopic Data

2020 ◽  
Vol 09 (03) ◽  
pp. 2050011
Author(s):  
Young Min Seo ◽  
Paul F. Goldsmith ◽  
Volker Tolls ◽  
Russell Shipman ◽  
Craig Kulesa ◽  
...  
Keyword(s):  
Data Reduction ◽  
Galactic Plane ◽  
Machine Learning Algorithms ◽  
Least Square ◽  
Gaussian Kernel ◽  
Science Data ◽  
Star Forming ◽  
Star Forming Regions ◽  
Level 1 ◽  
Level 2

We present the data reduction software and the distribution of Level 1 and Level 2 products of the Stratospheric Terahertz Observatory 2 (STO2). STO2, a balloon-borne Terahertz telescope, surveyed star-forming regions and the Galactic plane and produced approximately 300,000 spectra. The data are largely similar to spectra typically produced by single-dish radio telescopes. However, a fraction of the data contained rapidly varying fringe/baseline features and drift noise, which could not be adequately corrected using conventional data reduction software. To process the entire science data of the STO2 mission, we have adopted a new method to find proper off-source spectra to reduce large amplitude fringes and new algorithms including Asymmetric Least Square (ALS), Independent Component Analysis (ICA), and Density-based spatial clustering of applications with noise (DBSCAN). The STO2 data reduction software efficiently reduced the amplitude of fringes from a few hundred to 10[Formula: see text]K and resulted in baselines of amplitude down to a few K. The Level 1 products typically have noise of a few K in [CII] spectra and [Formula: see text]1[Formula: see text]K in [NII] spectra. Using a regridding algorithm, we made spectral maps of star-forming regions and the Galactic plane survey using an algorithm employing a Bessel–Gaussian kernel. The level 1 and level 2 products are available to the astronomical community through the STO2 data server and the DataVerse. The software is also accessible to the public through Github. The detailed addresses are given in Sec.  4 of this paper on data distribution.

Deep Level Analysis of Legitimacy in Bengali News Sentences

2022 ◽  
Vol 21 (1) ◽  
pp. 1-18
Author(s):  
Soma Das ◽  
Pooja Rai ◽  
Sanjay Chatterji
Keyword(s):  
Deep Level ◽  
Research Direction ◽  
Machine Learning Algorithms ◽  
Supervised Machine Learning ◽  
News Article ◽  
Support Vector ◽  
Potential Threat ◽  
Annotation Guideline ◽  
Level 1 ◽  
Level 2

The tremendous increase in the growth of misinformation in news articles has the potential threat for the adverse effects on society. Hence, the detection of misinformation in news data has become an appealing research area. The task of annotating and detecting distorted news article sentences is the immediate need in this research direction. Therefore, an attempt has been made to formulate the legitimacy annotation guideline followed by annotation and detection of the legitimacy in Bengali e-papers. The sentence-level manual annotation of Bengali news has been carried out in two levels, namely “Level-1 Shallow Level Classification” and “Level-2 Deep Level Classification” based on semantic properties of Bengali sentences. The tagging of 1,300 anonymous Bengali e-paper sentences has been done using the formulated guideline-based tags for both levels. The validation of the annotation guideline has been done by applying benchmark supervised machine learning algorithms using the lexical feature, syntactic feature, domain-specific feature, and Level-2 specific feature in both levels. Performance evaluation of these classifiers is done in terms of Accuracy, Precision, Recall, and F-Measure. In both levels, Support Vector Machine outperforms other benchmark classifiers with an accuracy of 72% and 65% in Level-1 and Level-2, respectively.

scholarly journals A Study of Low density Ionized Gas in the Galactic Plane

2002 ◽  
Vol 199 ◽  
pp. 335-338
Author(s):  
D. Anish Roshi ◽  
K. R. Anantharamaiah
Keyword(s):  
Radio Telescope ◽  
Radial Distribution ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Hii Regions ◽  
Low Density ◽  
Ionized Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Complete Survey

A complete survey of radio recombination lines (RRLs) near 327 MHz from the galactic plane (l = 330° − 0°-89°, b = 0°) was carried out using a section of the Ooty Radio Telescope (ORT) with an angular resolution of 2° × 2°. A subset of regions in the same area was observed using the whole telescope which has a beam of 2° × 6'. Hydrogen RRLs were detected in most of the positions that were observed. The lv diagram and radial distribution computed from the observed spectra and their comparison with other species in the galactic plane indicate that the low density gas detected in the survey is distributed similar to the star forming regions. For an assumed temperature of 7000 K, we estimate that the densities and sizes of the regions are in the range 1 — 10 cm−3 and 20 — 200 pc respectively. Our data suggests that the low density ionized gas is in the form of outer envelopes of normal HII regions.

scholarly journals Image Digitisation of Outflows and the AAO/UKST Hα Survey

1998 ◽  
Vol 15 (1) ◽  
pp. 165-166
Author(s):  
W. J. Zealey ◽  
S. L. Mader
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Galactic Plane ◽  
Star Forming ◽  
Star Forming Regions ◽  
Sky Survey ◽  
High Resolution Images ◽  
Line Survey

AbstractThe Hα emission-line survey of the Southern Sky to be carried out by the AAO/UKST will provide deep, high resolution images of Galactic Plane sources allowing the detection of new and existing filamentary sources such as Herbig–Haro objects. Used in conjunction with the existing ESO/SERC Southern Sky Survey Plates, the Hα plates will provide us with the opportunity to study the morphology and environment of new and existing star forming regions.

scholarly journals 22 GHz Water Maser Survey of the Xinjiang Astronomical Observatory

2012 ◽  
Vol 8 (S287) ◽  
pp. 296-297
Author(s):  
Jian-jun Zhou ◽  
Jarken Esimbek ◽  
Gang Wu
Keyword(s):  
Galactic Plane ◽  
Astronomical Observatory ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Gas Kinematics ◽  
Star Forming Regions ◽  
Water Masers ◽  
Maser Sources ◽  
Water Maser

AbstractWater masers are good tracers of high-mass star-forming regions. Water maser VLBI observations provide a good probe for studying high-mass star formation and galactic structure. We plan to make a blind survey toward the northern Galactic plane in future years using the 25 m radio telescope of the Xinjiang Astronomical Observatory. We will select some water maser sources discovered in the survey and perform high resolution observations to study the gas kinematics close to high-mass protostars.

scholarly journals First Results from ATCA at Millimetre Wavelengths

2004 ◽  
Vol 221 ◽  
pp. 275-282
Author(s):  
Vincent Minier
Keyword(s):  
Star Formation ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Dust Emission ◽  
Protoplanetary Disks ◽  
High Angular Resolution ◽  
Star Forming ◽  
Star Forming Regions ◽  
First Results ◽  
Excellent Tool

The newly upgraded Australia Telescope Compact Array (ATCA) at millimetre wavelengths is the first millimetre interferometer to be built in the Southern Hemisphere. The full array will be operational in 2004-2005 and will provide arcsec angular resolution at 3 mm and 12 mm. This will be a unique instrument to study at high angular resolution the interstellar chemistry and more generally the star formation process, especially in the bulk of the galactic plane and in the Magellanic Clouds. The upgraded ATCA will also be an excellent tool to detect dust emission from nearby protoplanetary disks. In this paper I will present the first results from the upgraded ATCA at 3 mm and 12 mm. The result review will cover the topics of massive star formation and hot molecular cores dust emission from star-forming regions and detection of protoplanetary disks.

scholarly journals The spiral potential of the Milky Way

2018 ◽  
Vol 619 ◽  
pp. A50 ◽  
Author(s):  
P. Grosbøl ◽  
G. Carraro
Keyword(s):  
Radial Velocity ◽  
Galactic Center ◽  
Galactic Plane ◽  
Small Mass ◽  
The Sun ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Best Fit ◽  
Armed Spiral

Context. The location of young sources in the Galaxy suggests a four-armed spiral structure, whereas tangential points of spiral arms observed in the integrated light at infrared and radio wavelengths indicate that only two arms are massive. Aims. Variable extinction in the Galactic plane and high light-to-mass ratios of young sources make it difficult to judge the total mass associated with the arms outlined by such tracers. The current objective is to estimate the mass associated with the Sagittarius arm by means of the kinematics of the stars across it. Methods. Spectra of 1726 candidate B- and A-type stars within 3◦ of the Galactic center (GC) were obtained with the FLAMES instrument at the VLT with a resolution of ≈6000 in the spectral range of 396–457 nm. Radial velocities were derived by least-squares fits of the spectra to synthetic ones. The final sample was limited to 1507 stars with either Gaia DR2 parallaxes or main-sequence B-type stars having reliable spectroscopic distances. Results. The solar peculiar motion in the direction of the GC relative to the local standard of rest (LSR) was estimated to U⊙ = 10.7 ± 1.3kms−1. The variation in the median radial velocity relative to the LSR as a function of distance from the sun shows a gradual increase from slightly negative values near the sun to almost 5 km s−1 at a distance of around 4 kpc. A sinusoidal function with an amplitude of 3.4 ± 1.3kms−1 and a maximum at 4.0 ± 0.6 kpc inside the sun is the best fit to the data. A positive median radial velocity relative to the LSR around 1.8 kpc, the expected distance to the Sagittarius arm, can be excluded at a 99% level of confidence. A marginal peak detected at this distance may be associated with stellar streams in the star-forming regions, but it is too narrow to be associated with a major arm feature. Conclusions. A comparison with test-particle simulations in a fixed galactic potential with an imposed spiral pattern shows the best agreement with a two-armed spiral potential having the Scutum–Crux arm as the next major inner arm. A relative radial forcing dFr ≈ 1.5% and a pattern speed in the range of 20–30 km s−1 kpc−1 yield the best fit. The lack of a positive velocity perturbation in the region around the Sagittarius arm excludes it from being a major arm. Thus, the main spiral potential of the Galaxy is two-armed, while the Sagittarius arm is an inter-arm feature with only a small mass perturbation associated with it.

scholarly journals Micro-arcsecond astrometry with the VLBA

2007 ◽  
Vol 3 (S248) ◽  
pp. 141-147 ◽  
Author(s):  
M. J. Reid
Keyword(s):  
Galactic Center ◽  
Galactic Plane ◽  
Proper Motions ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Trigonometric Parallaxes ◽  
Sgr A ◽  
Definition Of ◽  
Almost All

AbstractThe VLBA is now achieving parallaxes and proper motions with accuracies approaching the micro-arcsecond domain. The apparent proper motion of Sgr A*, which reflects the orbit of the Sun around the Galactic center, has been measured with high accuracy. This measurement strongly constrains Θ0/R0 and offers a dynamical definition of the Galactic plane with Sgr A*at its origin. The intrinsic motion of Sgr A*is very small and comparable to that expected for a supermassive black hole. Trigonometric parallaxes and proper motions for a number of massive star forming regions (MSFRs) have now been measured. For almost all cases, kinematic distances exceed the true distances, suggesting that the Galactic parameters, R0 and Θ0, are inaccurate. Solutions for the Solar Motion are in general agreement with those obtained from Hipparcos data, except that MSFRs appear to be rotating slower than the Galaxy. Finally, the VLBA has been used to measure extragalactic proper motions and to map masers in distant AGN accretion disks, which will yield direct estimates of H0.

scholarly journals Gaussian kernel in quantum learning

2020 ◽  
Vol 18 (03) ◽  
pp. 2050006
Author(s):  
Arit Kumar Bishwas ◽  
Ashish Mani ◽  
Vasile Palade
Keyword(s):  
Random Access ◽  
Nonlinear Problems ◽  
Machine Learning Algorithms ◽  
Least Square ◽  
Gaussian Kernel ◽  
Support Vector ◽  
Classical Counterpart ◽  
Quantum Version ◽  
Quantum Polynomial ◽  
Polynomial Kernels

The Gaussian kernel is a very popular kernel function used in many machine learning algorithms, especially in support vector machines (SVMs). It is more often used than polynomial kernels when learning from nonlinear datasets and is usually employed in formulating the classical SVM for nonlinear problems. Rebentrost et al. discussed an elegant quantum version of a least square support vector machine using quantum polynomial kernels, which is exponentially faster than the classical counterpart. This paper demonstrates a quantum version of the Gaussian kernel and analyzes its runtime complexity using the quantum random access memory (QRAM) in the context of quantum SVM. Our analysis shows that the runtime computational complexity of the quantum Gaussian kernel is approximated to [Formula: see text] and even [Formula: see text] when [Formula: see text] and the error [Formula: see text] are small enough to be ignored, where [Formula: see text] is the dimension of the training instances, [Formula: see text] is the accuracy, [Formula: see text] is the dot product of the two quantum states, and [Formula: see text] is the Taylor remainder error term. Therefore, the run time complexity of the quantum version of the Gaussian kernel seems to be significantly faster when compared with its classical version.

scholarly journals THE BOLOCAM GALACTIC PLANE SURVEY. VII. CHARACTERIZING THE PROPERTIES OF MASSIVE STAR-FORMING REGIONS

2011 ◽  
Vol 741 (2) ◽  
pp. 110 ◽  
Author(s):  
Miranda K. Dunham ◽  
Erik Rosolowsky ◽  
Neal J. Evans II ◽  
Claudia Cyganowski ◽  
James S. Urquhart
Keyword(s):  
Massive Star ◽  
Galactic Plane ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals Water Masers Toward Star-Forming Regions in the Bolocam Galactic Plane Survey

2012 ◽  
Vol 8 (S287) ◽  
pp. 286-287 ◽  
Author(s):  
Miranda K. Dunham ◽  
Keyword(s):  
Physical Properties ◽  
Galactic Plane ◽  
Dust Emission ◽  
High Mass ◽  
Evolutionary Stage ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Water Masers ◽  
Green Bank Telescope

AbstractWe present preliminary results of a search for 22 GHz water masers toward 1400 star-forming regions seen in the Bolocam Galactic Plane Survey (BGPS) using the Green Bank Telescope (GBT). The BGPS is a blind survey of the Northern Galactic plane in 1.1 mm thermal dust emission that has cataloged star-forming regions at all evolutionary stages. Further information is required to determine the stage of each BGPS source. Since water masers are produced by outflows from low and high-mass star forming regions, their presence is a key component of determining whether the BGPS sources are forming stars and which evolutionary stage they are in. We present preliminary detection statistics, basic properties of the water masers, and correlations with physical properties determined from the 1.1 mm emission and ammonia observations obtained concurrently with the water masers on the GBT.

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