4,584 research outputs found
Michael Davittâs wartime visit to South Africa (MarchâMay 1900) and its consequences
In view of renewed interest in the radical Irish nationalist leader and land reform agitator Michael Davitt and his ideas, this article reconsiders his much publicised fact-finding visit to the war-torn Boer republics in South Africa and its context. Davitt resigned as an Irish nationalist member of parliament (MP) from the British House of Commons over the Anglo-Boer War, rather than any Irish issue. He was in South Africa from late March to early May 1900, where he met the leaders of the republics and senior generals. On his return to Ireland, Davitt wrote a 600-page partisan book on the Anglo-Boer War. The South African experience remained special to him. After his return to Europe, Davitt became closely associated with the Kruger-exile coterie, drifting away from mainline Irish nationalism. This article traces Davittâs visit and discusses the effect it had on him, on Irish nationalism and on the Boer republics he visited.Keywords: Michael Davitt, Ireland, South Africa, Anglo-Boer Wa
Review of test methods used for the measurement of hermeticity in packages containing small cavities
An Invisible Quantum Tripwire
We present here a quantum tripwire, which is a quantum optical interrogation
technique capable of detecting an intrusion with very low probability of the
tripwire being revealed to the intruder. Our scheme combines interaction-free
measurement with the quantum Zeno effect in order to interrogate the presence
of the intruder without interaction. The tripwire exploits a curious nonlinear
behaviour of the quantum Zeno effect we discovered, which occurs in a lossy
system. We also employ a statistical hypothesis testing protocol, allowing us
to calculate a confidence level of interaction-free measurement after a given
number of trials. As a result, our quantum intruder alert system is robust
against photon loss and dephasing under realistic atmospheric conditions and
its design minimizes the probabilities of false positives and false negatives
as well as the probability of becoming visible to the intruder.Comment: Improved based on reviewers comments; 5 figure
The clustering properties of radio-selected AGN and star-forming galaxies up to redshifts z~3
We present the clustering properties of a complete sample of 968 radio
sources detected at 1.4 GHz by the VLA-COSMOS survey with radio fluxes brighter
than 0.15 mJy. 92% have redshift determinations from the Laigle et al. (2016)
catalogue. Based on their radio-luminosity, these objects have been divided
into two populations of 644 AGN and 247 star-forming galaxies. By fixing the
slope of the auto-correlation function to gamma=2, we find
r_0=11.7^{+1.0}_{-1.1} Mpc for the clustering length of the whole sample, while
r_0=11.2^{+2.5}_{-3.3} Mpc and r_0=7.8^{+1.6}_{-2.1} Mpc (r_0=6.8^{+1.4}_{-1.8}
Mpc if we restrict our analysis to z<0.9) are respectively obtained for AGN and
star-forming galaxies. These values correspond to minimum masses for dark
matter haloes of M_min=10^[13.6^{+0.3}_{-0.6}] M_sun for radio-selected AGN and
M_min=10^[13.1^{+0.4}_{-1.6}] M_sun for radio-emitting star-forming galaxies
(M_min=10^[12.7^{+0.7}_{-2.2}] M_sun for z<0.9). Comparisons with previous
works imply an independence of the clustering properties of the AGN population
with respect to both radio luminosity and redshift. We also investigate the
relationship between dark and luminous matter in both populations. We obtain
/M_halo/M_halo<~10^{-2.4} in the case of
star-forming galaxies. Furthermore, if we restrict to z<~0.9 star-forming
galaxies, we derive /M_halo<~10^{-2.1}, result which clearly indicates the
cosmic process of stellar build-up as one moves towards the more local
universe. Comparisons between the observed space density of radio-selected AGN
and that of dark matter haloes shows that about one in two haloes is associated
with a black hole in its radio-active phase. This suggests that the
radio-active phase is a recurrent phenomenon.Comment: 11 pages, 7 figures, minor changes to match published version on
MNRA
Evolution of hierarchical clustering in the CFHTLS-Wide since z~1
We present measurements of higher order clustering of galaxies from the
latest release of the Canada-France-Hawaii-Telescope Legacy Survey (CFHTLS)
Wide. We construct a volume-limited sample of galaxies that contains more than
one million galaxies in the redshift range 0.2<z<1 distributed over the four
independent fields of the CFHTLS. We use a counts in cells technique to measure
the variance and the hierarchical moments S_n = /^(n-1)
(3<n<5) as a function of redshift and angular scale.The robustness of our
measurements if thoroughly tested, and the field-to-field scatter is in very
good agreement with analytical predictions. At small scales, corresponding to
the highly non-linear regime, we find a suggestion that the hierarchical
moments increase with redshift. At large scales, corresponding to the weakly
non-linear regime, measurements are fully consistent with perturbation theory
predictions for standard LambdaCDM cosmology with a simple linear bias.Comment: 17 pages, 11 figures, submitted to MNRA
Understanding Durban University of Technology Studentsâ Perceptions of Biodiversity Loss
Biodiversity loss has been recognised as a global and local problem of increasing magnitude. As future leaders, university students may play an influential role in alleviating this serious and multifaceted problem. This particular research focuses on a relatively new area of study not yet covered in the literature, that of South African university studentsâ perceptions and understandings of biodiversity. This paper seeks to describe the knowledge, attitudes and perceptions of students at Durban University of Technology towards biodiversity and to consider some of the socio-cultural causal factors. Student opinions were sampled using an appropriate survey modelled after European biodiversity surveys and adapted to meet the unique challenges of South African conditions and rich biodiversity found in Durbanâs urban green spaces. The quantitative data were then merged with qualitative data drawn from four focus groups sampled across selected faculties at the institution. The focus groups involved guided discussion on the relevance of biodiversity, viewing of video clips and local field visits to Pigeon Valley Nature Reserve and the Durban Botanic Gardens. The results indicated high levels of concern for biodiversity loss and strong cultural connections with traditional African medicinal plants
Ruddy Shelduck Tadorna ferruginea home range and habitat use during the non-breeding season in Assam, India
India is an important non-breeding ground for migratory waterfowl in the Central Asian Flyway. Millions of birds visit wedands across the country, yet information on their distribution, abundance, and use of resources is rudimentary at best. Limited information suggests that populations of several species of migratory ducks are declining due to encroachment of wedand habitats largely by agriculture and industry. The development of conservation strategies is stymied by a lack of ecological information on these species. We conducted a preliminary assessment of the home range and habitat use of Ruddy Shelduck Tadornaferruginea in the northeast Indian state of Assam. Seven Ruddy Shelducks were fitted with solar-powered Global Positioning System (GPS) satellite transmitters, and were tracked on a daily basis during the winter of 2009-2010. Locations from all seven were used to describe habitat use, while locations from four were used to quantify their home range, as the other three had too few locations (<30) for home range estimation. A Brownian Bridge Movement Model (BBMM), used to estimate home ranges, found that the Ruddy Shelduck had an average core use area (i.e. the contour defining 50% of positions) of 40 km 2 (range = 22-87 km2) and an average home range (95% contour) of 610 km2 (range = 222-1,550 km2). Resource Selection Functions (RSF), used to describe habitat use, showed that the birds frequented riverine wetlands more than expected, occurred on grasslands and shrublands in proportion to their availability, and avoided woods and cropland habitats. The core use areas for three individuals (75%) were on the Brahmaputra River, indicating their preference for riverine habitats. Management and protection of riverine habitats and nearby grasslands may benefit conservation efforts for the Ruddy Shelduck and waterfowl species that share these habitats during the non-breeding seaso
Differential Cross Section and Recoil Polarization Measurements for the \u3ci\u3eÎłp\u3c/i\u3eâ\u3ci\u3eK\u3c/i\u3e\u3csup\u3e+\u3c/sup\u3eÎ Reaction Using CLAS at Jefferson Lab
We present measurements of the differential cross section and \u27B; recoil polarization for the Îłp â K+Î reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles. Independent analyses were performed using the K+pÏâ and K+p (missing Ïâ) final-state topologies; results from these analyses were found to exhibit good agreement. These differential-cross-section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300-MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500-MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of nonresonant K+\u27B; photoproduction mechanisms at all production angles
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