scholarly journals Grand, A Giant Radio Array For Neutrino Detection: Objectives, Design And Current Status

2019 ◽  
Vol 216 ◽  
pp. 01006
Author(s):  
Matias Tueros
Keyword(s):  
Angular Resolution ◽  
Point Sources ◽  
Current Status ◽  
Air Shower ◽  
Neutrino Detection ◽  
Open Questions ◽  
Large Numbers ◽  
Radio Transients ◽  
Construction Plans ◽  
Do So

The Giant Radio Array for Neutrino Detection (GRAND) aims to answer one of the most pressing open questions in astrophysics: what is the origin of ultra-highenergy cosmic rays (UHECRs)?. It will do so indirectly: UHECRs make secondary UHE neutrinos which encode information about the properties of UHECRs and their sources. GRAND is designed to discover UHE neutrinos even under pessimistic predictions of their flux, reaching a sensitivity of 6x10−9GeV.cm−2.s−1.sr−1 around 109GeV. It will do so by using 20 sub-arrays of 10 000 radio antennas forming a total detector area of 200 000 km2, making it the largest air-shower detector ever built. With this sensitivity, GRAND will discover cosmogenic neutrinos in 3 years of operation, even in disfavorable scenarios. Because of its subdegree angular resolution, GRAND will also search for point sources of UHE neutrinos, both steady and transient. Moreover, GRAND will be a valuable instrument for astronomy and cosmology, allowing for the discovery and followup of large numbers of radio transients - fast radio bursts, giant radio pulses - and studies of the epoch of reionization. In this contribution we will present briefly some of the science goals, detection strategy, construction plans and current status of the GRAND project.

The current status of the GRAPES-3 extensive air shower experiment

2009 ◽  
Vol 196 ◽  
pp. 153-158 ◽  
Author(s):  
S.K. Gupta ◽  
H.M. Antia ◽  
S.R. Dugad ◽  
U.D. Goswami ◽  
Y. Hayashi ◽  
...  
Keyword(s):  
Current Status ◽  
Extensive Air Shower ◽  
Air Shower

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A18 ◽  
Author(s):  
C. H. A. Logan ◽  
B. J. Maughan ◽  
M. N. Bremer ◽  
P. Giles ◽  
M. Birkinshaw ◽  
...  
Keyword(s):  
Angular Resolution ◽  
False Positive Rate ◽  
High Sensitivity ◽  
Point Sources ◽  
Selection Function ◽  
X Rays ◽  
Cluster Emission ◽  
X Ray ◽  
Wide Range ◽  
Function Modelling

Context. The XMM-XXL survey has used observations from the XMM-Newton observatory to detect clusters of galaxies over a wide range in mass and redshift. The moderate PSF (FWHM ~ 6″ on-axis) of XMM-Newton means that point sources within or projected onto a cluster may not be separated from the cluster emission, leading to enhanced luminosities and affecting the selection function of the cluster survey. Aims. We present the results of short Chandra observations of 21 galaxy clusters and cluster candidates at redshifts z > 1 detected in the XMM-XXL survey in X-rays or selected in the optical and infra-red. Methods. With the superior angular resolution of Chandra, we investigate whether there are any point sources within the cluster region that were not detected by the XMM-XXL analysis pipeline, and whether any point sources were misclassified as distant clusters. Results. Of the 14 X-ray selected clusters, 9 are free from significant point source contamination, either having no previously unresolved sources detected by Chandra or with less than about 10% of the reported XXL cluster flux being resolved into point sources. Of the other five sources, one is significantly contaminated by previously unresolved AGN, and four appear to be AGN misclassified as clusters. All but one of these cases are in the subset of less secure X-ray selected cluster detections and the false positive rate is consistent with that expected from the XXL selection function modelling. We also considered a further seven optically selected cluster candidates associated with faint XXL sources that were not classed as clusters. Of these, three were shown to be AGN by Chandra, one is a cluster whose XXL survey flux was highly contaminated by unresolved AGN, while three appear to be uncontaminated clusters. By decontaminating and vetting these distant clusters, we provide a pure sample of clusters at redshift z > 1 for deeper follow-up observations, and demonstrate the utility of using Chandra snapshots to test for AGN in surveys with high sensitivity but poor angular resolution.

Historical Contingencies in the Evolution of States and Their Militaries

2018 ◽  
Vol 71 (1) ◽  
pp. 126-161
Author(s):  
Jonathan Bendor ◽  
Jacob N. Shapiro
Keyword(s):  
International Relations ◽  
Law Of Large Numbers ◽  
International System ◽  
Critical Role ◽  
Selection Environment ◽  
Large Numbers ◽  
Key Players ◽  
Chance Events ◽  
The Impact ◽  
Do So

AbstractHistorians and some scholars of international relations have long argued that historical contingencies play a critical role in the evolution of the international system, but have not explained whether they do so to a greater extent than in other domains or why such differences may exist. The authors address these lacunae by identifying stable differences between war and other policy domains that render the evolution of the international system more subject to chance events than those other domains. The selection environment of international politics has produced tightly integrated organizations (militaries) as the domain’s key players to a much greater degree than other policy domains. Because there are few players, no law of large numbers holds, and because militaries are tightly integrated, microshocks can reverberate up to macro-organizational levels. The anarchic character of the international system amplifies the impact of these shocks. The authors explore these phenomena in a range of historical examples.

scholarly journals Habitat Protection Indexes - new monitoring measures for the conservation of coastal and marine habitats

2021 ◽  
Author(s):  
Joy A Kumagai ◽  
Fabio Favoretto ◽  
Sara Pruckner ◽  
Alex David Rogers ◽  
Lauren V Weatherdon ◽  
...  
Keyword(s):  
Biodiversity Loss ◽  
Current Status ◽  
Sustainable Development Goal ◽  
Development Goal ◽  
Habitat Protection ◽  
Marine Habitats ◽  
Freshwater Habitats ◽  
National Jurisdiction ◽  
Global Biodiversity ◽  
Do So

A worldwide call to implement habitat protection aims to halt biodiversity loss. To monitor the extent of coastal and marine habitats within protected areas (PAs) in a standardized, open source, and reproducible way, we constructed the Local and the Global Habitat Protection Indexes (LHPI and GHPI, respectively). The LHPI pinpoints the jurisdictions with the greatest opportunity to expand their own PAs, while the GHPI showcases which jurisdictions contribute the most in area to the protection of these habitats globally. Jurisdictions were evaluated to understand which have the highest opportunity to contribute globally to the protection of habitats by meeting a target of 30% coverage of PAs with Areas Beyond National Jurisdiction (ABNJ) having the greatest opportunity to do so. While we focus on marine and coastal habitats, our workflow can be extended to terrestrial and freshwater habitats. These indexes are useful to monitor aspects of Sustainable Development Goal 14 and the emerging post-2020 Global Biodiversity Framework, to understand the current status of international cooperation on coastal and marine habitats conservation.

Key Concepts and Definitions of Open Source Communities

2010 ◽  
pp. 753-760
Author(s):  
Ruben van Wendel de Joode ◽  
Sebastian Spaeth
Keyword(s):  
Software Development ◽  
Open Source ◽  
Open Source Software ◽  
Online Communities ◽  
Source Code ◽  
Professional Organizations ◽  
Large Numbers ◽  
Key Concepts ◽  
Open Source Communities ◽  
Do So

Most open source software is developed in online communities. These communities are typically referred to as “open source software communities” or “OSS communities.” In OSS communities, the source code, which is the human-readable part of software, is treated as something that is open and that should be downloadable and modifiable to anyone who wishes to do so. The availability of the source code has enabled a practice of decentralized software development in which large numbers of people contribute time and effort. Communities like Linux and Apache, for instance, have been able to connect thousands of individual programmers and professional organizations (although most project communities remain relatively small). These people and organizations are not confined to certain geographical places; on the contrary, they come from literally all continents and they interact and collaborate virtually.

scholarly journals Search for point sources of ultra-high-energy photons with the Telescope Array surface detector

2020 ◽  
Vol 492 (3) ◽  
pp. 3984-3993 ◽  
Author(s):  
R U Abbasi ◽  
M Abe ◽  
T Abu-Zayyad ◽  
M Allen ◽  
R Azuma ◽  
...  
Keyword(s):  
Point Source ◽  
Cosmic Ray ◽  
High Energy ◽  
Point Sources ◽  
Ultra High Energy ◽  
Telescope Array ◽  
Air Shower ◽  
Upper Limits ◽  
Surface Detector ◽  
Blind Search

ABSTRACT The surface detector (SD) of the Telescope Array (TA) experiment allows us to detect indirectly photons with energies of the order of 1018 eV and higher, and to separate photons from the cosmic ray background. In this paper, we present the results of a blind search for point sources of ultra-high-energy (UHE) photons in the Northern sky using the TA SD data. The photon-induced extensive air showers are separated from the hadron-induced extensive air shower background by means of a multivariate classifier based upon 16 parameters that characterize the air shower events. No significant evidence for the photon point sources is found. The upper limits are set on the flux of photons from each particular direction in the sky within the TA field of view, according to the experiment’s angular resolution for photons. The average 95 per cent confidence level upper-limits for the point-source flux of photons with energies greater than 1018, 1018.5, 1019, 1019.5 and 1020 eV are 0.094, 0.029, 0.010, 0.0073 and 0.0058 km−2yr−1, respectively. For energies higher than 1018.5 eV, the photon point-source limits are set for the first time. Numerical results for each given direction in each energy range are provided as a supplement to this paper.

scholarly journals Telescope Array Experiment

2019 ◽  
Vol 208 ◽  
pp. 08002
Author(s):  
Shoichi Ogio
Keyword(s):  
Cosmic Ray ◽  
Low Energy ◽  
Current Status ◽  
Future Prospects ◽  
Fluorescence Detector ◽  
Telescope Array ◽  
Air Shower ◽  
Primary Particles ◽  
Shower Array ◽  
Air Shower Array

The Telescope Array is the largest hybrid cosmic ray detector in the Northern hemisphere designed to measure primary particles in 4 PeV to 100 EeV range. The main TA detector consists of an air shower array of 507 plastic scintillation counters on a 1.2 km square grid and fluorescence detectors at three stations overlooking the sky above the air shower array. The experiment and its recent measurements - spectrum, composition, and anisotropy - is reviewed. Recently the construction of the TA Low energy Extension (TALE) detector, which consists of an additional fluorescence detector and an infill array, was finished. TALE lowers the energy threshold of TA down to 4 PeV. We are also constructing the TAx4 detector to increase statistics in particular at the highest energies. The current status and the future prospects of these new TAx4 experiments is reported.

scholarly journals The Nature of Unconscious Attention to Subliminal Cues

Vision ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 38 ◽  
Author(s):  
Prasad ◽  
Mishra
Keyword(s):  
Attentional Capture ◽  
Response Times ◽  
Attentional Selection ◽  
Current Status ◽  
Future Directions ◽  
Open Questions ◽  
Selection History ◽  
Spatial Cuing ◽  
Attentional System ◽  
The Individual

Attentional selection in humans is mostly determined by what is important to them or by the saliency of the objects around them. How our visual and attentional system manage these various sources of attentional capture is one of the most intensely debated issues in cognitive psychology. Along with the traditional dichotomy of goal-driven and stimulus-driven theories, newer frameworks such as reward learning and selection history have been proposed as well to understand how a stimulus captures attention. However, surprisingly little is known about the different forms of attentional control by information that is not consciously accessible to us. In this article, we will review several studies that have examined attentional capture by subliminal cues. We will specifically focus on spatial cuing studies that have shown through response times and eye movements that subliminal cues can affect attentional selection. A majority of these studies have argued that attentional capture by subliminal cues is entirely automatic and stimulus-driven. We will evaluate their claims of automaticity and contrast them with a few other studies that have suggested that orienting to unconscious cues proceeds in a manner that is contingent with the top-down goals of the individual. Resolving this debate has consequences for understanding the depths and the limits of unconscious processing. It has implications for general theories of attentional selection as well. In this review, we aim to provide the current status of research in this domain and point out open questions and future directions.

scholarly journals MSX Sources in the LMC: Dust-Enshrouded AGB Stars, Post-AGB Stars and PN

2003 ◽  
Vol 209 ◽  
pp. 52-52
Author(s):  
P. R. Wood ◽  
M. Cohen
Keyword(s):  
Near Infrared ◽  
Point Sources ◽  
Agb Stars ◽  
Large Numbers ◽  
Red Supergiants ◽  
Selection Of

The Midcourse Space (MSX) Experiment (Price 1995) detected large numbers of point sources in the LMC at 8.28 μm (Egan et al. 2001). Near-infrared J H K L imaging and monitoring of the 504 MSX sources in a region of size 3° x 3.5° covering most of the LMC bar has been carried out. Spectra have been taken for most of the post-AGB stars and a selection of the AGB stars and red supergiants.

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