165 research outputs found
The pulsating magnetosphere of the extremely slowly rotating magnetic beta Cep star xi(1) CMa
No full textxi(1) CMa is a monoperiodically pulsating, magnetic beta Cep star with magnetospheric X-ray emission that, uniquely amongst magnetic stars, is clearly modulated with the star's pulsation period. The rotational period P-rot has yet to be identified, with multiple competing claims in the literature. We present an analysis of a large ESPaDOnS data set with a 9 yr baseline. The longitudinal magnetic field < B-z > shows a significant annual variation, suggesting that Prot is at least of the order of decades. The possibility that the star's Ha emission originates around a classical Be companion star is explored and rejected based upon Very Large Telescope Interferometer AMBER and PIONIER interferometry, indicating that the emission must instead originate in the star's magnetosphere and should therefore also be modulated with Prot. Period analysis of Ha equivalent widths measured from ESPaDOnS and CORALIE spectra indicates P-rot > 30 yr. All evidence thus supports that xi(1) CMa is a very slowly rotating magnetic star hosting a dynamical magnetosphere. Ha also shows evidence for modulation with the pulsation period, a phenomenon that we show cannot be explained by variability of the underlying photospheric line profile, i.e. it may reflect changes in the quantity and distribution of magnetically confined plasma in the circumstellar environment. In comparison to other magnetic stars with similar stellar properties, xi(1) CMa is by far the most slowly rotating magnetic B-type star, is the only slowly rotating B-type star with a magnetosphere detectable in Ha ( and thus, the coolest star with an optically detectable dynamical magnetosphere), and is the only known early-type magnetic star with Ha emission modulated by both pulsation and rotation
B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars beta CMa and epsilon CMa
No full textpeer reviewedWithin the context of the "B fields in OB stars (BOB)" collaboration, we used the HARPSpol spectropolarimeter to observe the early B-type stars beta CMa (HD44743; B1 II/III) and epsilon CMa (HD52089; B1.5 II). For both stars, we consistently detected the signature of a weak (<30 G in absolute value) longitudinal magnetic field. We determined the physical parameters of both stars and characterise their X-ray spectrum. For beta CMa, our mode identification analysis led to determining a rotation period of 13.6+/-1.2 days and of an inclination angle of the rotation axis of 57.6+/-1.7 degrees, with respect to the line of sight. On the basis of these measurements and assuming a dipolar field geometry, we derived a best fitting obliquity of ~22 degrees and a dipolar magnetic field strength (Bd) of ~100 G (60<Bd<230 G within 1 sigma), below what is typically found for other magnetic massive stars. For epsilon CMa we could only determine a lower limit on the dipolar magnetic field strength of 13 G. For this star, we determine that the rotation period ranges between 1.3 and 24 days. Both stars are expected to have a dynamical magnetosphere. We also conclude that both stars are most likely core hydrogen burning and that they have spent more than 2/3 of their main sequence lifetime. A histogram of the distribution of the dipolar magnetic field strength for the magnetic massive stars known to date does not show the magnetic field "desert" observed instead for intermediate-mass stars. The biases involved in the detection of (weak) magnetic fields in massive stars with the currently available instrumentation and techniques imply that weak fields might be more common than currently observed. Our results show that, if present, even relatively weak magnetic fields are detectable in massive stars and that more observational effort is probably still needed to properly access the magnetic field incidence
Occupational health guidelines for the management of low back pain: an international comparison
No full textThe enormous socioeconomic burden of low back pain emphasises the need for effective management of this problem, especially in an occupational context. To address this, occupational guidelines have been issued in various countries
Il ruolo della revisione nell'internazionalizzazione delle imprese: il caso della CMA macchine agricole.
No full textThis dissertation has been written within the framework of the Language Toolkit project, a collaboration between companies in the Forlì area and the course in Specialized Translation of the University of Bologna. The project aims to bring together the students' skills in translation, localization and revision with the companies' needs for internationalization. This work concerns the revision of the international website of CMA, a company that produces and sells agricultural machinery. The site, localized in English from its Italian version, has been revised not only in terms of language, but also in terms of terminology consistency and adequacy to the genre of the website. The process was guided not only by the theoretical principles of revision, localization and internationalization, but also of writing for the web and controlled authoring. This theoretical background has been implemented in the analysis both of the communicative context, carried out in collaboration with the company, and in that of the linguistic content, which has been designed as revision of samples. The latter made it possible to highlight the shortcomings of the text and to establish the intervention methodologies in agreement with the CMA itself. The constant dialogue with the company was also fundamental in order to devise a tailored strategy to correct the errors that had not been highlighted by the analysis of the samples. The results are a more consistent use of terminology, and a website that meets the expectations and habits of web users, a feature that increases the satisfaction of potential customers and improves the image of the company. The glossary and the controlled writing rules created during the revision process can be used both to harmonize the paper materials of the company with the new website, and to revise its Italian version, as it is lacking terminological consistency. In the past, this fault has caused problems for both the employees and the customers of the CMA
Submission to the Paris Agreement Implementation and Compliance Committee Regarding its Draft Rules of Procedure
No full textThe Paris Agreement Implementation and Compliance Committee (PAICC) is one of the core mechanisms established by Parties to hold themselves accountable for their treaty implementation actions. In Decision 20/CMA.1, the Conference of the Parties serving as the meeting of the Parties to the Paris Agreement (CMA) requested the PAICC to develop its own Rules of Procedure for consideration and adoption by the CMA. The Rules of Procedure offer a unique opportunity to enhance the accountability relationships that can be established between the PAICC and Parties, in accordance with its facilitative, transparent, non-adversarial and non-punitive mandate.
The present submission comments on the draft Rules of Procedure published by the PAICC as Annex 2 to the report on its 5th meeting in August 2021. It builds on research conducted by the author on the negotiation of the Paris Agreement and of the Paris Rulebook since 2014 as well as enriching comments by Dr Joanna Depledge and Mr Miguel Saldivia, both of whom are also affiliated to the Cambridge Centre for Environment, Energy and Natural Resource Governance (C-EENRG). The author acts independently from any institution, in a spirit of constructive collaboration with the PAICC, and in light of the PAICC’s power to seek expert advice as needed. Proposed text is provided in bold and italics regarding 1) Draft Rule 22 (Significant and Persistent Inconsistencies), 2) Draft Rule 26 (Accessing Support), 3) Draft Rule 26 (Action Plans), and 4) Draft Rule 27 (Systemic Issues).
3 May 2022</p
Positivity and strong ellipticity
No full textWe consider partial differential operators H = − div(C∇) in divergence
form on Rᵈ with a positive-semidefinite, symmetric, matrix C of real
L∞-coefficients, and establish that H is strongly elliptic if and only if the associated
semigroup kernel satisfies local lower bounds, or, if and only if the
kernel satisfies Gaussian upper and lower bounds.This work was carried out while the first author was visiting the Centre for Mathematics and
its Applications at the Australian National University. He thanks the Australian Research Council
for its support and the CMA for its hospitality. The third author was an ARC Research Associate
for the duration of the collaboration
Search for Nonresonant Higgs Boson Pair Production in the Four Leptons Plus twob Jets Final State in Proton-Proton Collisions at √s = 13 TeV
No full textThe first search for nonresonant production of Higgs boson pairs (HH) with one H decaying into four leptons and the other into a pair of b quarks is presented, using proton-proton collisions recorded at a center-of-mass energy of √s = 13 TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 138 fb−1. A 95% confidence level upper limit of 32.4 is set on the signal strength modifier μ, defined as the ratio of the observed HH production rate in the HH ⟶ ZZ*bb[bar] ⟶ 4ℓb[bar] decay channel to the standard model (SM) expectation. Possible modifications of the H trilinear coupling λHHH with respect to the SM value are investigated. The coupling modifier κλ, defined as λHHH divided by its SM prediction, is constrained to be within the observed (expected) range −8.8 (−9.8) \u3c κλ \u3c 13.4 (15.0) at 95% confidence level
Mechanical and corrosion behaviour of 3D printed aluminium bronzes produced by wire+arc additive manufacturing: In collaboration with RAMLAB
No full textThe emerging field of 3D printing has expanded to the fabrication of metallic components during the last decade. Among the most prominent applications is the production of aluminium bronze marine propellers by the Wire+Arc Additive Manufacturing (WAAM) method. This method incorporates a welding system attached to a robotic arm. The final product results after sequential bead depositions. The main assets of the method are the efficient material usage and the minimization of lead time, which both have a positive environmental and economic impact. The aim of this project is to evaluate the feasibility to produce 3D printed aluminium bronze (CMA and NAB alloys) blocks with the WAAM method and compare the mechanical and corrosion properties of the blocks with the market requirements. In order to achieve that, rectangular blocks were manufactured at the facilities of Delft University of Technology and at Rotterdam Additive Manufacturing Fieldlab (RAMLAB). Cross sectional areas were extracted and used for microstructural investigation and for hardness measurement. Subsequently, the blocks were machined to produce tensile and Charpy specimens along the built height. Finally, corrosion tests were performed, including open circuit potential measurements, polarization experiments and Scanning Kelvin Probe (SKP) tests.The microstructural investigation revealed that the 3D printed CMA block consisted of a banded structure. The deposited layers consisted of two dominant phases, α and β, and a variety of precipitates. The Widmanstätten α phase nucleates at the grain boundaries mainly. The tempering promotes the growth of the α phase, making the grain boundaries more indistinguishable, while the β phase decomposes.The mechanical testing results depicted that the hardness, the tensile strength and the absorption energy of the 3D printed blocks exceeded the specifications of the cast products, according to the ASTM standards. The built height direction is weaker than the welding direction; however, the deposition height plays no significant role in the mechanical properties. Samples were also tested after a heat treatment of 675 °C for 6 hours, as recommended in the literature. The result was a 25% reduction of the tensile yield strength and a 10% reduction of the ultimate tensile strength. However, the scatter in the measured values was reduced too. Regarding the corrosion results, the built height has little effect on the corrosion susceptibility, according to the polarization curves. The material exhibits a remarkable low corrosion rate, which justifies its use in marine applications. The Scanning Kelvin Probe (SKP) tests illustrated the beneficial aspect of the tempering heat treatment, which alleviates the large potential differences of adjacent deposited areas.It can be concluded that the CMA alloys are tolerable to the oscillations of the production parameters, making them appealing to the additive manufacturing industry. The mechanical properties achieved, outmatch not only the specifications for the cast CMA products, but also the performance of similar 3D printed aluminium bronze structures, found in the literature.Materials Science and Engineerin
Minimisation strategies for the determination of parton density functions
No full textWe discuss the current minimisation strategies adopted by research projects involving the determination of parton distribution functions (PDFs) and fragmentation functions (FFs) through the training of neural networks. We present a short overview of a proton PDF determination obtained using the covariance matrix adaptation evolution strategy (CMA-ES) optimisation algorithm. We perform comparisons between the CMA-ES and the standard nodal genetic algorithm (NGA) adopted by the NNPDF collaboration
Design and Application of Algorithm Intensive Environment for CMA Big Data and Cloud Platform
No full textWith the advancement of meteorological services, various product processing systems and supporting data management systems have been developed for different business systems. However, this has led to the problem of system non-intensification. The lack of intensification in meteorological services can result in inconsistent data standards and make the operation and maintenance more challenging, which can lead to significant waste in investment due to duplicate data storage and inconsistent data caused by untimely synchronization. Moreover, the lack of information and technology hinders the integration of upstream and downstream businesses.The intensive development of meteorological business systems and the reform of "cloud+end" technology system are important measures to achieve high-quality development of meteorological business. China Meteorological Administration proposed to build a "cloud+end" technology system in 2020. CMA Big Data and Cloud Platform serves as the cloud, while the meteorological business system is the end, clarifying the positioning of CMA Big Data and Cloud Platform as a key foundational technology platform. The data processing line (DPL) is an intensive environment for meteorological algorithms. It addresses business needs such as efficient and stable processing of data products, data sharing and collaboration among business systems, and efficient and intensive business applications. To achieve this goal, algorithm libraries and task control functions are established by utilizing technologies such as integrated digital and computing, efficient task scheduling, visual process arrangement, and containers. The algorithm library facilitates the standardization, unified management and sharing of algorithms. Task control supports multiple scheduling strategies with high reliability and fault tolerance, enabling efficient and stable scheduling operations for algorithms. All functions mentioned above are in the form of interfaces for the application frontend. At the same time, based on the meteorological business comprehensive monitoring system (referred to as Tianjing) enables automatic collection of algorithm operation status and detection of abnormal alarms. Since its operation in 2021, the processing assembly line has facilitated the real-time operation of 202 business systems nationwide, resulting in a performance improvement of 1-10 times and a significant increase in efficiency. It plays an important supporting role in improving the operational efficiency of business systems, enhancing their collaboration, accelerating the process of "cloud+end" business technology system reform, and promoting the intensive development of meteorological business
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