343 research outputs found
Automated Detection of Coronal Loops using a Wavelet Transform Modulus Maxima Method
We propose and test a wavelet transform modulus maxima method for the au-
tomated detection and extraction of coronal loops in extreme ultraviolet images
of the solar corona. This method decomposes an image into a number of size
scales and tracks enhanced power along each ridge corresponding to a coronal
loop at each scale. We compare the results across scales and suggest the
optimum set of parameters to maximise completeness while minimising detection
of noise. For a test coronal image, we compare the global statistics (e.g.,
number of loops at each length) to previous automated coronal-loop detection
algorithms
Prevalence of impairments, disabilities, handicaps and quality of life in the general population: a review of recent literature
International audienc
Discipline in Education
This book addresses a perennial challenge to the success of the South African education system, namely, discipline. This volume steers the interrogation of discipline in a new direction, reflecting on ways in which recent research can benefit South African schools. This includes the need for alternative discipline that will enhance education. The scholarly contribution lies in its in-depth exploration of the relevance of research findings to South African schools and to the twenty-first-century socio-political environment. For the first time, scholarly interrogation of the issue of learner discipline in South African schools draws on indigenous knowledge systems. Its post-colonial and decolonial perspectives offer an ethical and moral compass for behaviour that could contribute to the well-being of South African society (and other societies similarly afflicted by anti-social behaviour). The book offers a range of perspectives on the debates on discipline and associated issues, and should stimulate future discussions on discipline and indiscipline at a time when South Africa and many other societies engage with the effects of social and political transformation. This scholarly book is aimed at academics and researchers. The contributors include philosophers, moralists, corporativists, education law specialists, curriculum specialists, specialists in education and culture, advocates of ubuntu, and people using meta-syntheses of approaches and practices and religious practices such as a Christian ethical/moral approach to parental and school discipline. They draw on their insights into postcolonialism, the impact of indigenous knowledge, theories of agency, dysfunctionality and school underperformance. The book offers an intriguing depiction of opposing views on discipline
Constraining models of the large scale Galactic magnetic field with WMAP5 polarization data and extragalactic Rotation Measure sources
We introduce a method to quantify the quality-of-fit between data and
observables depending on the large scale Galactic magnetic field. We combine
WMAP5 polarized synchrotron data and Rotation Measures of extragalactic sources
in a joint analysis to obtain best fit parameters and confidence levels for GMF
models common in the literature. None of the existing models provide a good fit
in both the disk and halo regions, and in many instances best-fit parameters
are quite different than the original values. We note that probing a very large
parameter space is necessary to avoid false likelihood maxima. The thermal and
relativistic electron densities are critical for determining the GMF from the
observables but they are not well constrained. We show that some
characteristics of the electron densities can already be constrained using our
method and with future data it may be possible to carry out a self-consistent
analysis in which models of the GMF and electron densities are simultaneously
optimized.Comment: 27 pages, 13 figures. Accepted for publication in JCAP; arXiv version
updated to include minor revision
Discipline in Education
This book addresses a perennial challenge to the success of the South African education system, namely, discipline. This volume steers the interrogation of discipline in a new direction, reflecting on ways in which recent research can benefit South African schools. This includes the need for alternative discipline that will enhance education. The scholarly contribution lies in its in-depth exploration of the relevance of research findings to South African schools and to the twenty-first-century socio-political environment. For the first time, scholarly interrogation of the issue of learner discipline in South African schools draws on indigenous knowledge systems. Its post-colonial and decolonial perspectives offer an ethical and moral compass for behaviour that could contribute to the well-being of South African society (and other societies similarly afflicted by anti-social behaviour). The book offers a range of perspectives on the debates on discipline and associated issues, and should stimulate future discussions on discipline and indiscipline at a time when South Africa and many other societies engage with the effects of social and political transformation. This scholarly book is aimed at academics and researchers. The contributors include philosophers, moralists, corporativists, education law specialists, curriculum specialists, specialists in education and culture, advocates of ubuntu, and people using meta-syntheses of approaches and practices and religious practices such as a Christian ethical/moral approach to parental and school discipline. They draw on their insights into postcolonialism, the impact of indigenous knowledge, theories of agency, dysfunctionality and school underperformance. The book offers an intriguing depiction of opposing views on discipline
The <i>Castalia</i> mission to Main Belt Comet 133P/Elst-Pizarro
We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC’s activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA’s highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these
Ar plasma induced deep levels in epitaxial n-GaAs
Ar plasma etching of n-type (Si doped) GaAs introduces several electron traps (Ec - 0.04 eV,
Ec - 0.07 eV, Ec - 0.19 eV, Ec - 0.31 eV, Ec - 0.53 eV, and Ec - 0.61 eV). The trap, Ec - 0.04 eV,
labelled E10 and having a trap signature similar to irradiation induced defect E1, appears to be
metastable. Ec - 0.31 eV and Ec - 0.61 eV are metastable too and they are similar to the M3/M4
defect configuration present in hydrogen plasma exposed n-GaAs.South African National Research Foundationhttp://jap.aip.org/nf201
Second-generation colon capsule endoscopy compared with colonoscopy
Colon capsule endoscopy (CCE) represents a noninvasive technology
that allows visualization of the colon without requiring sedation and air
insufflation. A second-generation colon capsule endoscopy system (PillCam Colon
2) (CCE-2) was developed to increase sensitivity for colorectal polyp detection
compared with the first-generation system. OBJECTIVE: To assess the feasibility,
accuracy, and safety of CCE-2 in a head-to-head comparison with colonoscopy.
DESIGN AND SETTING: Prospective, multicenter trial including 8 European sites.
PATIENTS: This study involved 117 patients (mean age 60 years). Data from 109
patients were analyzed. INTERVENTION: CCE-2 was prospectively compared with
conventional colonoscopy as the criterion standard for the detection of
colorectal polyps that are >/=6 mm or masses in a cohort of patients at average
or increased risk of colorectal neoplasia. Colonoscopy was independently
performed within 10 hours after capsule ingestion or on the next day. MAIN
OUTCOME MEASUREMENTS: CCE-2 sensitivity and specificity for detecting patients
with polyps >/=6 mm and >/=10 mm were assessed. Capsule-positive but
colonoscopy-negative cases were counted as false positive. Capsule excretion
rate, level of bowel preparation, and rate of adverse events also were assessed.
RESULTS: Per-patient CCE-2 sensitivity for polyps >/=6 mm and >/=10 mm was 84%
and 88%, with specificities of 64% and 95%, respectively. All 3 invasive
carcinomas were detected by CCE-2. The capsule excretion rate was 88% within 10
hours. Overall colon cleanliness for CCE-2 was adequate in 81% of patients.
LIMITATIONS: Not unblinding the CCE-2 results at colonoscopy; heterogenous
patient population; nonconsecutive patients. CONCLUSION: In this European,
multicenter study, CCE-2 appeared to have a high sensitivity for the detection of
clinically relevant polypoid lesions, and it might be considered an adequate tool
for colorectal imaging
Time calibration of the ANTARES neutrino telescope
The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of similar to 1 ns. The methods developed to attain this level of precision are described
The positioning system of the ANTARES Neutrino Telescope
The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning system is described. It consists of an acoustic positioning system, for distance triangulation, and a compass-tiltmeter system, for the measurement of the orientation and inclination of the storeys. Necessary corrections are discussed and the results of the detector alignment procedure are described
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