scholarly journals The Lockman Hole Project: A Multi-frequency Study of the Faint Radio Population down to LOFAR bands

2013 ◽  
Vol 9 (S304) ◽  
pp. 108-109
Author(s):  
G. Guglielmino ◽  
I. Prandoni ◽  
R. Morganti ◽  
G. Heald ◽  
E. Mahony ◽  
...  
Keyword(s):  
Source Population ◽  
Low Frequencies ◽  
Radio Data ◽  
Preliminary Results ◽  
First Time ◽  
Lockman Hole

AbstractWe are performing a multi-frequency radio analysis of a well-known deep field: the Lockman Hole, which is one of the best studied sky regions in different wavebands. This will provide us with important complementary data (for example redshifts) to the radio data, allowing us to characterize the physical and evolutionary properties of the various classes of sources composing the faint radio population. LOFAR imaging of the Lockman Hole can play an important role in this project, allowing, for the very first time, to observe the sub-mJy source population at very low frequencies (30-200 MHz), where self-absorption phenomena are expected to be very important. Here we present some preliminary results.

scholarly journals HST-WFPC2 observations of Galactic Wolf-Rayet stars, preliminary results

1999 ◽  
Vol 193 ◽  
pp. 112-113 ◽  
Author(s):  
Debra J. Wallace ◽  
Michael M. Shara ◽  
Anthony F.J. Moffat ◽  
Virpi S. Niemela
Keyword(s):  
Radio Emission ◽  
Radio Data ◽  
Preliminary Results ◽  
Thermal Radio ◽  
New Information ◽  
Thermal Radio Emission ◽  
First Time

We present preliminary results of our HST-WFPC2 pc-survey of Wolf-Rayet stars. Initiated in 1996, the goal was to discover new companions to, and cluster/association memberships of, known Galactic WR stars. From these results, Niemela et al. (1998) have already established a firm link between non-thermal radio emission and the location of binary wind-collision zones for WR 146 (confirming radio data of Dougherty et al. 1996) and WR 147 (confirming radio and IR data of Williams et al. 1997; see also Williams, these Proceedings), and confirmed the presence of a binary companion for WR 86 (listed by Jeffers et al. 1963). Here, for the first time, we present new information on WR38, WR38a, and WR 104.

Spider diversity in the Bukit Timah Nature Reserve, Singapore

2019 ◽  
Vol 71 ((suppl.1)) ◽  
pp. 209-243
Author(s):  
J.K.H. Koh ◽  
D.J. Court
Keyword(s):  
Nature Reserve ◽  
New Records ◽  
Secondary Forest ◽  
Distinct Species ◽  
Primary Forest ◽  
Preliminary Results ◽  
Vegetation Zones ◽  
Comprehensive Survey ◽  
Quantitative Analyses ◽  
First Time

This paper discusses the preliminary results of the first comprehensive survey of the spiders of the Bukit Timah Nature Reserve (BTNR) in Singapore. Two plots were established in each of the three zones of vegetation, viz., primary forest, old secondary forest, and maturing secondary forest. They were repeatedly sampled over an 18-month period. Sorting of the collection so far suggests that the three vegetation zones harbour rather different spider assemblages. Only ~9% of the total spider fauna recovered was shared by all three zones. The results have also yielded a preliminary picture of dominance, abundance and rarity. Although first intended to obtain a baseline for future quantitative analyses, the survey became a testing ground to modify and refine methodology so as to conduct future quantitative surveys with greater scientific rigour. Taxonomic work on the samples so far shows that the spiders in the BTNR span over 43 families, of which six families are listed for the first time in Singapore. The tally is summarised in an interim checklist of BTNR spiders. The checklist, with a total of 317 entries, shows that there are 158 described species of spiders in BTNR, of which 25 species are new records for Singapore. Another 159 morphospecies are provisionally recognised as distinct species, some of which may be new to science. Our observations during the survey have allowed us to provide a narrative of BTNR spider diversity against a backdrop of their microhabitat specialisation.

TRANSMISSION ELECTRON MICROSCOPY OF SURFACE AND INTERFACIAL STEPS

1997 ◽  
Vol 04 (03) ◽  
pp. 559-566 ◽  
Author(s):  
J. M. GIBSON ◽  
X. CHEN ◽  
O. POHLAND
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Free Surface ◽  
Significant Loss ◽  
Stress Fields ◽  
Preliminary Results ◽  
Surface Steps ◽  
Transmission Electron ◽  
First Time

Transmission electron microscopy is uniquely able to extend techniques for imaging free surface steps to the buried interface regime, without significant loss of detail. Two mechanisms for imaging surface and interfacial steps by transmission electron microscopy are described. They are thickness contrast and strain contrast. The former reveals the position and approximate height of steps, whereas the latter detects stress fields which are commonly associated with steps. The basis for each of these methods is elaborated, and preliminary results are shown for step images at Si/SiO2 interfaces, where measurable stress fields have been directly detected for the first time.

Synthesis of α-Fluoro-β-lactones and Their Thermal Conversion to 1-Fluoroalkenes

2002 ◽  
Vol 67 (9) ◽  
pp. 1325-1334 ◽  
Author(s):  
Rogelio Ocampo ◽  
William R. Dolbier ◽  
Fabio Zuluaga
Keyword(s):  
Spectroscopic Properties ◽  
Thermal Conversion ◽  
Hydroxy Acids ◽  
Preliminary Results ◽  
First Time

α-Fluoro-β-lactones have been synthesized and isolated for the first time from α-fluoro-β-hydroxy acids by using the couple TsCl/DMAP as lactonization agent. A detailed description of the synthesis and spectroscopic properties of α-fluoro-β-lactones is presented. Preliminary results indicate that thermolysis of these new β-lactones produces 1-fluoroalkenes.

scholarly journals The sanctuary of Punta Stilo at Kaulonia-Monasterace (Rc, Italy): preliminary results of the close range photogrammetric surveys 2012-2013

2014 ◽  
Vol XL-5 ◽  
pp. 559-563
Author(s):  
E. Taccola ◽  
M. C. Parra ◽  
C. Ampolo
Keyword(s):  
Preliminary Results ◽  
3D Data ◽  
Close Range ◽  
The University ◽  
First Time

During the 2012–2013 excavations at the Sanctuary of Punta Stilo at Kaulonia, carried out by the University of Pisa and the Scuola Normale Superiore of Pisa, close range aerial and terrestrial photogrammetric surveys were tested for the first time. The aim of the test was to verify the accuracy of the site planimetry currently used, dating back also to a century ago. The 3D data obtained have allowed new data to be acquired for correcting and updating the mapping of the site.

Ebatronics: A New Paradigm for Experimental Laboratory in Applied Science and Technology

2021 ◽  
Vol 03 (04) ◽  
Author(s):  
Maide Bucolo ◽  
Arturo Buscarino ◽  
Luigi Fortuna ◽  
Salvina Gagliano
Keyword(s):  
Science And Technology ◽  
Applied Science ◽  
New Paradigm ◽  
Recycled Materials ◽  
New Approach ◽  
The Real ◽  
Preliminary Results ◽  
Experimental Laboratory ◽  
Laboratory Experiences ◽  
First Time

In this paper, the main concepts and the preliminary results related to a new approach for creating innovative green laboratory experiences in applied science and technology will be discussed. The term ebatronics is here introduced for the first time in the literature to indicate a kind of experimental laboratory based on the conjunction of wooden recycled materials and microcontroller based devices. In particular, tensegrity based systems are presented. A gallery of prototypes developed by the authors is shown. An intense set of photos will illustrate the real effectiveness of the proposed laboratory project.

scholarly journals A census of the pulsar population observed with the international LOFAR station FR606 at low frequencies (25–80 MHz)

2020 ◽  
Vol 635 ◽  
pp. A76 ◽  
Author(s):  
L. Bondonneau ◽  
J.-M. Grießmeier ◽  
G. Theureau ◽  
A. V. Bilous ◽  
V. I. Kondratiev ◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Range ◽  
Radio Pulsars ◽  
Low Frequencies ◽  
Radio Observatory ◽  
Future Studies ◽  
New Information ◽  
Upper Limits ◽  
Widespread Phenomenon ◽  
First Time

Context. To date, only 69 pulsars have been identified with a detected pulsed radio emission below 100 MHz. A LOFAR-core LBA census and a dedicated campaign with the Nançay LOFAR station in stand-alone mode were carried out in the years 2014–2017 in order to extend the known population in this frequency range. Aims. In this paper, we aim to extend the sample of known radio pulsars at low frequencies and to produce a catalogue in the frequency range of 25–80 MHz. This will allow future studies to probe the local Galactic pulsar population, in addition to helping explain their emission mechanism, better characterising the low-frequency turnover in their spectra, and obtaining new information about the interstellar medium through the study of dispersion, scattering, and scintillation. Methods. We observed 102 pulsars that are known to emit radio pulses below 200 MHz and with declination above −30°. We used the Low Band Antennas (LBA) of the LOw Frequency ARray (LOFAR) international station FR606 at the Nançay Radio Observatory in stand-alone mode, recording data between 25 and 80 MHz. Results. Out of our sample of 102 pulsars, we detected 64. We confirmed the existence of ten pulsars detected below 100 MHz by the LOFAR LBA census for the first time (Bilous et al. 2020, A&A, 635, A75) and we added two more pulsars that had never before been detected in this frequency range. We provided average pulse profiles, DM values, and mean flux densities (or upper limits in the case of non-detections). The comparison with previously published results allows us to identify a hitherto unknown spectral turnover for five pulsars, confirming the expectation that spectral turnovers are a widespread phenomenon.

scholarly journals Systematic effects in LOFAR data: A unified calibration strategy

2019 ◽  
Vol 622 ◽  
pp. A5 ◽  
Author(s):  
F. de Gasperin ◽  
T. J. Dijkema ◽  
A. Drabent ◽  
M. Mevius ◽  
D. Rafferty ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Low Frequency ◽  
Reduction Process ◽  
Spectral Energy ◽  
Ionospheric Scintillation ◽  
Source Population ◽  
Full Data ◽  
Low Frequencies ◽  
Beam Shape ◽  
Systematic Effects

Context. New generation low-frequency telescopes are exploring a new parameter space in terms of depth and resolution. The data taken with these interferometers, for example with the LOw Frequency ARray (LOFAR), are often calibrated in a low signal-to-noise ratio regime and the removal of critical systematic effects is challenging. The process requires an understanding of their origin and properties. Aim. In this paper we describe the major systematic effects inherent to next generation low-frequency telescopes, such as LOFAR. With this knowledge, we introduce a data processing pipeline that is able to isolate and correct these systematic effects. The pipeline will be used to calibrate calibrator observations as the first step of a full data reduction process. Methods. We processed two LOFAR observations of the calibrator 3C 196: the first using the Low Band Antenna (LBA) system at 42–66 MHz and the second using the High Band Antenna (HBA) system at 115–189 MHz. Results. We were able to isolate and correct for the effects of clock drift, polarisation misalignment, ionospheric delay, Faraday rotation, ionospheric scintillation, beam shape, and bandpass. The designed calibration strategy produced the deepest image to date at 54 MHz. The image has been used to confirm that the spectral energy distribution of the average radio source population tends to flatten at low frequencies. Conclusions. We prove that LOFAR systematic effects can be described by a relatively small number of parameters. Furthermore, the identification of these parameters is fundamental to reducing the degrees of freedom when the calibration is carried out on fields that are not dominated by a strong calibrator.

Measuring Radon and Thoron Levels in Sri Lanka

2013 ◽  
Vol 718-720 ◽  
pp. 721-724
Author(s):  
Deepal Subasinghe Nalaka ◽  
Mahakumara Prasad ◽  
Thusitha B. Nimalsiri ◽  
Nuwan B. Suriyaarchchi ◽  
Takeshi Iimoto ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Environmental Conditions ◽  
In Situ Measurements ◽  
Physical Factors ◽  
Preliminary Results ◽  
Radon Measurements ◽  
First Time

For the first time in Sri Lanka, an attempt was made to measure the outdoor radon levels using CR 39 type passive radon detectors. Preliminary results indicate that in Sri Lanka, 220Rn isotope is more abundance than 222Rn isotope. These results were also confirmed by in-situ measurements. Sri Lanka has one of the highest 220Rn values in the region. It was also noted that environmental conditions and other physical factors have a significant effect on the outdoor radon measurements using passive discriminative detectors.

scholarly journals A Magnetohydrodynamic Model of Galaxy Formation

1997 ◽  
Vol 163 ◽  
pp. 797-798
Author(s):  
J. P. Sleath ◽  
A. H. Nelson
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Formation ◽  
3D Model ◽  
Galactic Nuclei ◽  
Preliminary Results ◽  
Magnetohydrodynamic Model ◽  
The Creation ◽  
First Time

AbstractWe present a full 3D model of galaxy formation, incorporating for the first time magnetohydrodynamical effects. By this means we hope to simulate the creation of active galactic nuclei, including jets. Preliminary results are encouraging.

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