scholarly journals The Thousand-Pulsar-Array programme on MeerKAT – I. Science objectives and first results

2020 ◽  
Vol 493 (3) ◽  
pp. 3608-3615 ◽  
Author(s):  
Simon Johnston ◽  
A Karastergiou ◽  
M J Keith ◽  
X Song ◽  
P Weltevrede ◽  
...  
Keyword(s):  
Radio Emission ◽  
Single Pulse ◽  
Wide Band ◽  
Radio Pulsars ◽  
Pulse Trains ◽  
First Results ◽  
Dispersion Measures ◽  
Large Survey ◽  
First Time

ABSTRACT We report here on initial results from the Thousand-Pulsar-Array (TPA) programme, part of the Large Survey Project ‘MeerTime’ on the MeerKAT telescope. The interferometer is used in the tied-array mode in the band from 856 to 1712 MHz, and the wide band coupled with the large collecting area and low receiver temperature make it an excellent telescope for the study of radio pulsars. The TPA is a 5 year project, which aims at to observing (a) more than 1000 pulsars to obtain high-fidelity pulse profiles, (b) some 500 of these pulsars over multiple epochs, and (c) long sequences of single-pulse trains from several hundred pulsars. The scientific outcomes from the programme will include the determination of pulsar geometries, the location of the radio emission within the pulsar magnetosphere, the connection between the magnetosphere and the crust and core of the star, tighter constraints on the nature of the radio emission itself, as well as interstellar medium studies. First, results presented here include updated dispersion measures, 26 pulsars with Faraday rotation measures derived for the first time, and a description of interesting emission phenomena observed thus far.

scholarly journals Organised polarisation variability in radio pulsars and consequences for emission theory

2017 ◽  
Vol 13 (S337) ◽  
pp. 79-82
Author(s):  
Cristina-Diana Ilie ◽  
Patrick Weltevrede
Keyword(s):  
Radio Emission ◽  
Single Pulse ◽  
Position Angle ◽  
Emission Mechanism ◽  
Radio Pulsars ◽  
High Quality ◽  
Special Cases ◽  
High Quality Sample ◽  
Linear Polarisation ◽  
Periodic Switching

AbstractThe aim of this work is to explore the connection between variability in single pulse intensity and periodic switching of the position angle (PA) of the linear polarisation and how this relates to the radio emission mechanism. There are five pulsars reported in the literature for which the PA is seen to periodically change in tandem with the variability in their pulse shapes. This behaviour is seemingly incompatible with two well established models of the radio emission mechanism. The purpose of this study is to investigate in a systematic way whether this phenomenon is common or if only happens in special cases, using a high-quality sample of pulsar data observed with the Parkes telescope. We show that the connection between polarisation variability and intensity variability is more common than previously expected.

First Determination of the Proton's Weak Charge

2015 ◽  
Vol 8 (3) ◽  
Author(s):  
Shelley A. Page
Keyword(s):  
Standard Model ◽  
High Precision ◽  
Standard Model Prediction ◽  
Data Set ◽  
Weak Charge ◽  
Newport News ◽  
The Standard Model ◽  
First Results ◽  
First Time

The weak charge of the proton has been determined for the first time via a high precision electron-proton scattering experiment, Qweak, carried out at Jefferson Laboratory (JLab) in Newport News, USA. The weak charge is a basic property in subatomic physics, analogous to electric charge. The Standard Model makes a prediction for the weak charges of protons and other particles. First results described here are based on an initial 4% of the data set reported in 20131, with the ultimate goal of the experiment being a high precision Standard Model test conducted with the full Qweak data set. These initial results are consistent with the Standard Model prediction; they serve as an important first determination of the proton’s weak charge and a proof of principle that the ultimate goals are within reach.

scholarly journals Wide band simultaneous multi-frequency single pulse study of PSR J1822–2256 with upgraded GMRT

2017 ◽  
Vol 13 (S337) ◽  
pp. 348-349
Author(s):  
Bhal Chandra Joshi ◽  
Arun Naidu ◽  
Vishal Gajjar ◽  
Geoffrey A. E. Wright
Keyword(s):  
Radio Telescope ◽  
Drift Rate ◽  
Single Pulse ◽  
Wide Band ◽  
No Emission ◽  
Beam Geometry ◽  
Polar Gap ◽  
First Time

AbstractWe present simultaneous multi-frequency observations of PSR J1822–2256 for the first time, utilizing the unique capabilities of upgraded Giant Meterwave Radio Telescope (uGMRT). No emission is detected in about 10 % of pulses. At least two drift modes and a possibly third rare mode, occur for 66, 21 and 2 % pulses respectively (P3 ~ 17, 7.5 and 5 P0 respectively). The three drift modes and the nulls occur concurrently from 250 to 1500 MHz. Modal average profiles are distinct with their widths increasing with drift rate. These sub-pulse drift related profile mode-changes can provide independent probes of beam geometry and polar gap physics.

scholarly journals Superluminal Behaviour of the Double-Lobed Radio Galaxy 3C111

1988 ◽  
Vol 129 ◽  
pp. 105-106
Author(s):  
Eugen Preuss ◽  
Walter Alef ◽  
Kenneth I. Kellermann
Keyword(s):  
Radio Emission ◽  
Time Dependence ◽  
Radio Galaxy ◽  
Monitoring Program ◽  
Radio Galaxies ◽  
Scale Structure ◽  
Small Scale ◽  
Broad Line ◽  
First Results ◽  
First Time

Due to sensitivity problems only about a dozen of the powerful double-lobed radio galaxies have so far been mapped with VLBI. Even less is known about the time dependence of the small scale structure in these objects (Preuss and Alef, 1987). We have recently reported the first results of our monitoring program of classical double sources. We observed strong changes of the pc-scale structure in 3C111 (Götz et al., 1987) and 3C390.3 (Alef et al., 1987) implying “superluminal behaviour” in both sources. This is the first time that such a phenomenon has been found in lobe-dominated radio galaxies. Both objects are Broad Line Radio Galaxies of type N, and their radio emission from m to cm wavelengths is dominated by their outer lobes which are ∼300 kpc apart (H0 = 50 km/s/Mpc).

scholarly journals A GPU based single-pulse search pipeline (GSP) with database and its application to the Commensal Radio Astronomy FAST Survey (CRAFTS)

2022 ◽  
Vol 21 (12) ◽  
pp. 314
Author(s):  
Shan-Ping You ◽  
Pei Wang ◽  
Xu-Hong Yu ◽  
Xiao-Yao Xie ◽  
Di Li ◽  
...  
Keyword(s):  
Radio Astronomy ◽  
Data Streams ◽  
Single Pulse ◽  
Wide Band ◽  
Radio Bursts ◽  
Learning Tools ◽  
Radio Pulsars ◽  
Real Time Processing ◽  
Radio Transients ◽  
Rotating Radio Transients

Abstract We developed a GPU based single-pulse search pipeline (GSP) with a candidate-archiving database. Largely based upon the infrastructure of the open source PulsaR Exploration and Search Toolkit (PRESTO), GSP implements GPU acceleration of the de-dispersion and integrates a candidate-archiving database. We applied GSP to the data streams from the Commensal Radio Astronomy FAST Survey (CRAFTS), which resulted in quasi-real-time processing. The integrated candidate database facilitates synergistic usage of multiple machine-learning tools and thus improves efficient identification of radio pulsars such as rotating radio transients (RRATs) and fast radio bursts (FRBs). We first tested GSP on pilot CRAFTS observations with the FAST Ultra-Wide Band (UWB) receiver. GSP detected all pulsars known from the the Parkes multibeam pulsar survey in the corresponding sky area covered by the FAST-UWB. GSP also discovered 13 new pulsars. We measured the computational efficiency of GSP to be ∼120 times faster than the original PRESTO and ∼60 times faster than an MPI-parallelized version of PRESTO.

scholarly journals A pulsar census of the Local Group

2012 ◽  
Vol 8 (S291) ◽  
pp. 431-431 ◽  
Author(s):  
Vladislav Kondratiev ◽  
Duncan Lorimer ◽  
Maura McLaughlin ◽  
Scott Ransom
Keyword(s):  
Massive Star ◽  
Local Group ◽  
Single Pulse ◽  
Magellanic Clouds ◽  
Radio Telescopes ◽  
Radio Pulsars ◽  
Giant Pulses ◽  
History Of ◽  
Nearby Galaxies ◽  
Dispersion Measures

AbstractWe carried out a search for pulsars in nearby galaxies with the GBT and Arecibo radio telescopes at 820 and 327 MHz, correspondingly. Currently, the Magellanic Clouds are the only galaxies except for Milky Way known to harbor radio pulsars, with a total of 20 pulsars being discovered there to date. Discovery of pulsars in other galaxies can be used to trace the history of massive star formation and would allow to probe the intermediate intergalactic medium. We selected 22 galaxies of the Local Group at high galactic latitudes, |b| > 26 deg, with most of them being dwarf spheroidals with old star population. This makes them promising targets to search for giant pulses from recycled millisecond pulsars. Both single-pulse and periodicity searches were performed for trial dispersion measures up to 1000. No extragalactic pulsars are found in half of the selected targets processed so far. I will give the overview of our targetted searches, present potential candidates and discuss the obtained results.

scholarly journals FIRST DETERMINATION OF THE PROTON’S WEAK CHARGE

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Shelley A. Page
Keyword(s):  
Standard Model ◽  
High Precision ◽  
Standard Model Prediction ◽  
Data Set ◽  
Weak Charge ◽  
Newport News ◽  
The Standard Model ◽  
First Results ◽  
First Time

The weak charge of the proton has been determined for the first time via a high precision electron-proton scattering experiment, Qweak, carried out at Jefferson Laboratory (JLab) in Newport News, USA. The weak charge is a basic property in subatomic physics, analogous to electric charge. The Standard Model makes a prediction for the weak charges of protons and other particles. First results described here are based on an initial 4% of the data set reported in 20131 , with the ultimate goal of the experiment being a high precision Standard Model test conducted with the full Qweak data set. These initial results are consistent with the Standard Model prediction; they serve as an important first determination of the proton’s weak charge and a proof of principle that the ultimate goals are within reach.

Determination of the Recent Tectonic Movements Using GPS and Insar Methods; The First Results From the Eastern Part of the Gediz Graben

2015 ◽  
Author(s):  
Fatih POYRAZ ◽  
Orhan TATAR ◽  
Kemal Özgür HASTAOĞLU ◽  
İbrahim TİRYAKİOĞLU ◽  
Önder GÜRSOY ◽  
...  
Keyword(s):  
First Results ◽  
Tectonic Movements

Disability as a social phenomenon

2020 ◽  
pp. 22-38
Author(s):  
Natalia Guseva ◽  
Vitaliy Berdutin
Keyword(s):  
Social Protection ◽  
Russian Society ◽  
Stage Model ◽  
High Quality ◽  
Rehabilitation Programs ◽  
Current State ◽  
The Social ◽  
Consistent Solution ◽  
First Time

At present, the problem of establishing disability is a point at issue in Russia. Despite the fact that medical criteria for disability are being developed very actively, high-quality methods for assessing social hallmarks are still lacking. Since disability is a phenomenon inherent in any society, each state forms a social and economic policy for people with disabilities in accordance with its level of development, priorities and opportunities. We have proposed a three-stage model, which includes a system for the consistent solution of the main tasks aimed at studying the causes and consequences of the problems encountered today in the social protection of citizens with health problems. The article shows why the existing approaches to the determination of disability and rehabilitation programs do not correspond to the current state of Russian society and why a decrease in the rate of persons recognized as disabled for the first time does not indicate an improvement in the health of the population. The authors proposed a number of measures with a view to correcting the situation according to the results of the study.

Phytochemical Constituents of Annona reticulata and their Cytotoxic Activity

2020 ◽  
Vol 17 (3) ◽  
pp. 206-210
Author(s):  
Ty Viet Pham ◽  
Thang Quoc Le ◽  
Anh Tuan Le ◽  
Hung Quoc Vo ◽  
Duc Viet Ho
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Structural Determination ◽  
Phytochemical Investigation ◽  
Ic50 Values ◽  
Phytochemical Constituents ◽  
First Time ◽  
Annona Reticulata

A phytochemical investigation of the leaves of Annona reticulata led to the isolation and structural determination of β-sitosterol (1), ent-pimara-8(14),15-dien-19-oic acid (2), ent-pimara- 8(14),15-dien-19-ol (3), quercetin (4), quercetin 3-O-α-L-arabinopyranoside (5), and a mixture of quercetin 3-O-β-D-galactopyranoside (6a) and quercetin 3-O-β-D-glucopyranoside (6b). Of these, compounds 2 and 3 were isolated from the genus Annona for the first time. Compound 3 showed strong cytotoxicity against SK-LU-1 and SW626 cell lines with IC50 values of 17.64 ± 1.07 and 19.79 ± 1.41 μg mL-1, respectively.

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