1,721,757 research outputs found
Magnetic helicity and eruptivity in active region 12673
Get PDFInternational audienceContext. In September 2017, the largest X-class flare of solar cycle 24 occurred from the most active region (AR) of this cycle, AR 12673. This AR attracted much interest because of its unique morphological and evolution characteristics. Among the parameters that were examined in the AR was magnetic helicity, but either only approximately, or intermittently, or both.Aims. We here study the evolution of the relative magnetic helicity and of the two components of its decomposition, the non-potential, and the volume-threading one, in the time interval around the highest activity of AR 12673. We especially focus on the ratio of the non-potential to total helicity, which has recently been proposed as an indicator of AR eruptivity.Methods. We first approximated the coronal magnetic field of the AR with two different optimization-based extrapolation procedures, and chose the method that produced the most reliable helicity value at each instant. Moreover, in one of these methods, we weighted the optimization by the uncertainty estimates derived from the Helioseismic and Magnetic Imager (HMI) instrument for the first time. We then followed an accurate method to compute all quantities of interest.Results. The first observational determination of the evolution of the non-potential to total helicity ratio seems to confirm the quality it has in indicating eruptivity. This ratio increased before the major flares of AR 12673 and afterwards relaxed to lower values. Additionally, we discuss the evolution patterns of the various helicity and energy budgets of AR 12673 and compare them with results from other works
SPIE. DIGITAL LIBRARY
No full textThis work focuses on the description of face reconstruction by using several image techniques. The main purpose is to explore many opto-electronic configurations for camera capture in order to obtain an accurate reconstruction. In this work, we used different camera technologies and lenses for face reconstruction. We compared the analyzed techniques and applied objective measures to evaluate the best camera configuration for reconstruction accuracy. Computer simulation results are obtained in order to evaluate the performance of the proposed system in terms of reconstruction performance, and computational efficiency.SPIE. DIGITAL LIBRARYhttps://www.spiedigitallibrary.org/conference-proceedings-of-spie/12673/2678712/Exploring-opto-electronic-approaches-for-an-accurate-face-reconstruction/10.1117/12.2678712.shor
Lane detection and tracking algorithm implementation for an Ackermann-steering mobile robot
No full textThis paper presents the implementation of a lane detection and tracking algorithm for the autonomous navigation of an Ackermann-steering mobile robot. The proposed implementation employs an RGB camera mounted on the robot, the image information is processed through the lane detection and tracking algorithm to define the robot’s present and future position within the lane. This information is used to determine the orientation of the wheels required to steer the robot within the lane. The implementation employs a Raspberry Pi as the primary logic controller to process the image received from the RGB camera. The Ackermann-steering mobile robot performs steering and navigation with a proportional-integral-derivative controller that manages the orientation of the steering. Experimental results are presented to validate the implementation considering a physical implementation of the Ackermann-steering mobile robot.https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12673/2677791/Lane-detection-and-tracking-algorithm-implementation-for-an-Ackermann-steering/10.1117/12.2677791.shor
A parakeet specimen held at National Museums Scotland is a unique skin of the extinct Réunion Parakeet Psittacula eques eques: a reply to Cheke and Jansen
Get PDFCheke and Jansen (2016) questioned the identity
of a parakeet specimen at National Museums
Scotland (NMS), Edinburgh, which is considered
in a paper by Jackson et al. (2015) to be a specimen
of the extinct R eunion Parakeet Psittacula
eques eques (Boddaert, 1783). They suggest that
with the available information, its provenance cannot
be ascribed with any certainty and it is most
likely, on the basis of probability, to be from Mauritius,
although they do not exclude the possibility
that the parakeet comes from R eunion, the neighbouring
island of Mauritius. The provenance and
identity of this specimen has previously been questioned
(Jones 1987, Hume 2007, Hume & Walters
2012), with the possibility that it may be a Mauritius
Parakeet Psittacula eques echo. Since these
accounts were written, more work conducted
on Psittacula parakeets of the Indian Ocean Islands
indicates that the Edinburgh specimen is a
R eunion Parakeet, and Cheke and Jansen (2016)
would have been unaware of some of this work.This is the peer reviewed version of the following article: Jones, C. G., Jackson, H. A., McGowan, R. Y., Hume, J. P., Forshaw, J. M., Tatayah, V. , Winters, R. and Groombridge, J. J. (2019), A parakeet specimen held at National Museums Scotland is a unique skin of the extinct Réunion Parakeet Psittacula eques eques: a reply to Cheke and Jansen (). Ibis, 161: 230-238. doi:10.1111/ibi.12673, which has been published in final form at doi:10.1111/ibi.12673. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.NHM Repositor
Specific detection of Campylobacter jejuni using the bacteriophage NCTC 12673 receptor binding protein as a probe
Get PDFCampylobacter jejuni is found in the intestines of poultry, cattle, swine, wild birds and pet animals and is the major cause of foodborne gastroenteritis in developed countries. We report the use of the receptor binding protein (RBP) of Campylobacter bacteriophage NCTC 12673 for the specific capture of Campylobacter jejuni bacteria using RBP-derivatized capturing surfaces. The Gp48 RBP was expressed as a glutathione S-transferase-Gp48 (GST-Gp48) fusion protein and immobilized onto surface plasmon resonance (SPR) surfaces using glutathione self-assembled monolayers (GSH SAM). Bovine serum albumin (BSA) was used to block any non-specific binding. Glutathione SAM leads to an oriented attachment of the protein, resulting in a two- to three-fold improvement of bacterial capture when compared to dithiobis(succinimidyl propionate) (DTSP) SAM-based unoriented attachment. The specificity of recognition was confirmed using Salmonella enterica subsp. enterica serovar Typhimurium as a negative control, which indeed showed negligible binding. The detection limit of the RBPderivatized SPR surfaces was found to be 102 cfu/ml. Finally, GST-Gp48 was also immobilized onto magnetic beads that were successfully used to capture and pre-concentrate the host pathogen from suspension
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Genome and proteome of Campylobacter jejuni bacteriophage NCTC 12673
No full textCampylobacter jejuni continues to be the leading cause of bacterial food-borne illness worldwide, so improvements to current methods used for bacterial detection and disease prevention are needed. We describe here the genome and proteome of C. jejuni bacteriophage NCTC 12673 and the exploitation of its receptor-binding protein for specific bacterial detection. Remarkably, the 135-kb Myoviridae genome of NCTC 12673 differs greatly from any other proteobacterial phage genome described (including C. jejuni phages CP220 and CPt10) and instead shows closest homology to the cyanobacterial T4-related myophages. The phage genome contains 172 putative open reading frames, including 12 homing endonucleases, no visible means of packaging, and a putative trans-splicing intein. The phage DNA appears to be strongly associated with a protein that interfered with PCR amplification and estimation of the phage genome mass by pulsed-field gel electrophoresis. Identification and analyses of the receptor-binding protein (Gp48) revealed features common to the Salmonella enterica P22 phage tailspike protein, including the ability to specifically recognize a host organism. Bacteriophage receptor-binding proteins may offer promising alternatives for use in pathogen detection platforms.Peer reviewed: YesNRC publication: Ye
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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