14 research outputs found
Holographic Jet Shapes and their Evolution in Strongly Coupled Plasma
No full text© 2017 The Author(s) Recently our group analyzed how the probability distribution for the jet opening angle is modified in an ensemble of jets that has propagated through an expanding cooling droplet of plasma [K. Rajagopal, A. V. Sadofyev, W. van der Schee, Phys. Rev. Lett. 116 (2016) 211603]. Each jet in the ensemble is represented holographically by a string in the dual 4+1- dimensional gravitational theory with the distribution of initial energies and opening angles in the ensemble given by perturbative QCD. In [K. Rajagopal, A. V. Sadofyev, W. van der Schee, Phys. Rev. Lett. 116 (2016) 211603], the full string dynamics were approximated by assuming that the string moves at the speed of light. We are now able to analyze the full string dynamics for a range of possible initial conditions, giving us access to the dynamics of holographic jets just after their creation. The nullification timescale and the features of the string when it has nullified are all results of the string evolution. This emboldens us to analyze the full jet shape modification, rather than just the opening angle modification of each jet in the ensemble as in [K. Rajagopal, A. V. Sadofyev, W. van der Schee, Phys. Rev. Lett. 116 (2016) 211603]. We find the result that the jet shape scales with the opening angle at any particular energy. We construct an ensemble of dijets with energies and energy asymmetry distributions taken from events in proton-proton collisions, opening angle distribution as in [K. Rajagopal, A. V. Sadofyev, W. van der Schee, Phys. Rev. Lett. 116 (2016) 211603], and jet shape taken from proton-proton collisions and scaled according to our result. We study how these observables are modified after we send the ensemble of dijets through the strongly-coupled plasma
Astrofyzikální procesy v blízkosti kompaktních objektů
No full textTitle: Astrophysical processes near compact objects: studying extremal en- ergy shifts from accretion rings Author: Vjačeslav Sochora Department: Academy of Sciences of the Czech Republic, Astronomical In- stitute Supervisor: doc. RNDr. Vladimír Karas, DrSc.; Academy of Sciences of the Czech Republic, Astronomical Institute Abstract: The X-ray emission from inner regions of an accretion disk around black holes provides wealth of information about matter in extreme con- ditions. A spectral profile of radiation from a narrow circular ring has a characteristic double-horn profile. Red and blue peaks of the profile are close to the extremal values of the energy shift. We describe a useful approach to calculate the extremal energy shifts in the regime of strong gravity. We dis- cuss if the radial structure of the disk emission could be reconstructed using extremal energy shifts of the individual rings. For this purpose, we simulate artificial data from a bright active galactic nucleus and show that the re- quired sensitivity and energy resolution can be reached with the proposed LOFT mission. Keywords: black hole physics, accretion disks, galactic nucle
Astrofyzikální procesy v blízkosti kompaktních objektů: studium extremálních posuvů energie z akrečních prstenců
No full textNázev práce: Astrofyzikální procesy v blízkosti kompaktních objektů: studium extremálních posuvů energie z akrečních prstenců Autor: Vjačeslav Sochora Pracoviště: Astronomický ústav AV ČR Vedoucí disertační práce: doc. RNDr. Vladimír Karas, DrSc., Astronomický ústav AV ČR Abstrakt: Rentgenové záření z vnitřních oblastí akrečního disku okolo černých děr poskytuje velké množství informací o hmotě v extrémních podmínkách. Spektrální profil záření z úzkého, kruhového prstence má charakteristický tvar s dvěma maximy. Červený a modrý vrchol profilu leží blízko extremálních hodnot energetického posuvu čáry. Popisujeme užitečný postup výpočtu ex- tremálních energetických posuvů v režimu silné gravitace. Diskutujeme, zda radiální struktura emise disku může být rekonstruována užitím extrémních energetických posuvů jednotlivých prstenců. Za tímto účelem simulujeme umělá data z jasného galaktického jádra a ukazujeme, že požadované citlivosti a energetického rozlišení může být dosaženo s navrženou misí LOFT. Klíčová slova: fyzika černých děr, akreční disky, galaktická jádraTitle: Astrophysical processes near compact objects: studying extremal en- ergy shifts from accretion rings Author: Vjačeslav Sochora Department: Academy of Sciences of the Czech Republic, Astronomical In- stitute Supervisor: doc. RNDr. Vladimír Karas, DrSc.; Academy of Sciences of the Czech Republic, Astronomical Institute Abstract: The X-ray emission from inner regions of an accretion disk around black holes provides wealth of information about matter in extreme con- ditions. A spectral profile of radiation from a narrow circular ring has a characteristic double-horn profile. Red and blue peaks of the profile are close to the extremal values of the energy shift. We describe a useful approach to calculate the extremal energy shifts in the regime of strong gravity. We dis- cuss if the radial structure of the disk emission could be reconstructed using extremal energy shifts of the individual rings. For this purpose, we simulate artificial data from a bright active galactic nucleus and show that the re- quired sensitivity and energy resolution can be reached with the proposed LOFT mission. Keywords: black hole physics, accretion disks, galactic nucleiMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Development of a general education course on quantum information science
No full textGeneral education plays a vital role in the mission of higher education to cultivate responsible and engaged citizens with a global awareness (CUHK, 2013; Benander, Denton, Page, & Skinner, 2000). Besides humanities and social science, the category of nature, science and technology is a critical part of general education (CUHK(SZ), 2021; Vander Schee, 2011) as it will help students to appraise the physical world with a scientific attitude, evaluate humans’ role in being part of nature and assess the impact of science and technology on modern life (CUHK(SZ), 2021) by introducing various principles, discoveries, and methods of natural sciences as well as modern technology. Quantum physics has been revolutionizing modern life since its appearance in 20th century. The rapid development of quantum information science is bringing a new age. The education of quantum information science for the younger generation, in particular for those who are not specialized in physics, is becoming increasingly demanded. Therefore, a course on quantum information science is becoming an indispensable part of general education.
The author developed a general education course on quantum information science at the Chinese University of Hong Kong, Shenzhen in China for non-physics major undergraduates in 2015. Three themes including how quantum mechanics was developed, what quantum mechanics is about and how quantum mechanics relates to modern life, are addressed. In this work, challenges of teaching quantum information science as a general education course and possible solutions will be presented based on the seven-year teaching experience of the author.
REFERENCES
Benander, R., Denton, J., Page, D., & Skinner, C. (2000). Primary trait analysis: Anchoring assessment in the classroom. Journal of General Education, 49(4), 279-302.
CUHK Misson of University General Education (2013), Retrieved August 20, 2022, from https://www.oge.cuhk.edu.hk/index.php/en/overview/mission,
CUHKS(SZ) General Education Study Scheme, 2021, Retrieved August 20, 2022, from https://registry.cuhk.edu.cn/en/page/21
Vander Schee, B. A. (2011), Changing General Education Perceptions through Perspectives and the Interdisciplinary First-Year Seminar, International Journal of Teaching and Learning in Higher Education, 23(3), 382-387
The development of understanding of evidence in pre-university biology education in the Netherlands
No full textEnsuring the quality of investigations requires the understanding of procedures by which empirical evidence is obtained. This can be interpreted as becoming aware of and using criteria for evidence in one's mental structure. The question is whether this process can be observed in practice. In two schools for pre-university education where 11th grade students were working in small groups on open investigations in biology, all conversations in class -with or without the teacher participating- of eight groups (17 students) were audio-taped and transcribed. All utterances concerning the quality of investigations (3943 in total) were analyzed using five categories: problematization, description, explanation, generalization and application. Half of the students received written feedback twice, the other half paused their own investigations to carry out four specially designed reflection tasks. Talking about the reflection tasks as well as having the teacher present in conversations about investigations have shown to stimulate the spiral of description, explanation and generalization. Students who did the reflection tasks explained and generalized significantly more than students who did not. Still, the majority of the explanations and generalizations came from the teacher. Implications for the role of reflection and the role of the teacher in developing procedural understanding are discussed. © 2011 The Author(s)
Measurements of azimuthal anisotropies of jet production in Pb+ Pb collisions at sNN =5.02 TeV with the ATLAS detector
No full textIndexación: Scopus.The azimuthal variation of jet yields in heavy-ion collisions provides information about the path-length dependence of the energy loss experienced by partons passing through the hot, dense nuclear matter known as the quark-gluon plasma. This paper presents the azimuthal anisotropy coefficients v2, v3, and v4 measured for jets in Pb+Pb collisions at sNN=5.02 TeV using the ATLAS detector at the LHC. The measurement uses data collected in 2015 and 2018, corresponding to an integrated luminosity of 2.2 nb-1. The vn values are measured as a function of the transverse momentum of the jets between 71 and 398 GeV and the event centrality. A nonzero value of v2 is observed in all but the most central collisions. The value of v2 is largest for jets with lower transverse momentum, with values up to 0.05 in mid-central collisions. A smaller, nonzero value of v3 of approximately 0.01 is measured with no significant dependence on jet pT or centrality, suggesting that fluctuations in the initial state play a small but distinct role in jet energy loss. No significant deviation of v4 from zero is observed in the measured kinematic region. © 2022 CERN. for the ATLAS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.https://journals-aps-org.recursosbiblioteca.unab.cl/prc/abstract/10.1103/PhysRevC.105.064903We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; Minciencias, Colombia; MEYS CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3- CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRI, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MEiN, Poland; FCT, Portugal; MNE/IFA, Romania; JINR; MES of Russia and NRC KI, Russian Federation; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DSI/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, USA. In addition, individual groups and members have received support from BCKDF, CANARIE, Compute Canada and CRC, Canada; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d’Avenir Labex, Investissements d’Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and GIF, Israel; Norwegian Financial Mechanism 2014-2021, Norway; NCN and NAWA, Poland; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in Ref. [49]. [1] W. Busza, K. Rajagopal, and W. van der Schee, Heavy ion collisions: The big picture, and the big questions, Annu. Rev. Nucl. Part. Sci. 68, 339 (2018). [2] ATLAS Collaboration, Measurement of the nuclear modification factor for inclusive jets in Pb+Pb collisions at √sNN = 5.02 TeV with the ATLAS detector, Phys. Lett. B 790, 108 (2019). [3] CMS Collaboration, First measurement of large area jet transverse momentum spectra in heavy-ion collisions, J. High Energy Phys. 05 (2021) 284. [4] X.-N. Wang, Jet quenching and azimuthal anisotropy of large pT spectra in noncentral high-energy heavy-ion collisions, Phys. Rev. C 63, 054902 (2001). [5] M. Gyulassy, I. Vitev, and X.-N. Wang, High pT Azimuthal Asymmetry in Noncentral A + A at RHIC, Phys. Rev. Lett. 86, 2537 (2001). [6] E. V. Shuryak, Azimuthal asymmetry at large pt seem to be too large for a pure “jet quenching,” Phys. Rev. C 66, 027902 (2002). [7] U. Heinz and R. Snellings, Collective flow and viscosity in relativistic heavy-ion collisions, Annu. Rev. Nucl. Part. Sci. 63, 123 (2013). [8] PHENIX Collaboration, Azimuthal anisotropy of π0 and η mesons in Au + Au collisions at √sNN = 200 GeV, Phys. Rev. C 88, 064910 (2013). [9] STAR Collaboration, AzimuthalS
1-year results after PCI with the COMBO stent in all-comers in Asia versus Europe: Geographical insights from the COMBO collaboration
No full textBackground: The COMBO drug-eluting stent combines sirolimus-elution from a biodegradable polymer with an anti-CD34+ antibody coating for early endothelialization. Objective: We investigated for geographical differences in outcomes after percutaneous coronary intervention (PCI) with the COMBO stent among Asians and Europeans. Methods: The COMBO Collaboration is a pooled patient-level analysis of the MASCOT and REMEDEE registries of all-comers undergoing attempted COMBO stent PCI. The primary outcome was 1-year target lesion failure (TLF), composite of cardiac death, target vessel myocardial infarction (TV-MI) and target lesion revascularization (TLR). Results: This study included 604 Asians (17.9%) and 2775 Europeans (82.1%). Asians were younger and included fewer females, with a higher prevalence of diabetes mellitus but lower prevalence of other comorbidities than Europeans. Asians had a higher prevalence of ACC/AHA C type lesions and received longer stent lengths. More Asians than Europeans were discharged on clopidogrel (86.5% vs 62.8%) rather than potent P2Y12 inhibitors. One-year TLF occurred in 4.0% Asians and 4.1% of Europeans, p = 0.93. The incidence of cardiac death was higher in Asians (2.8% vs. 1.3%, p = 0.007) with similar rates of TV-MI (1.5% vs. 1.2%, p = 0.54) and definite stent thrombosis (0.3% vs. 0.5%, p = 0.84) and lower incidence of TLR than Europeans (1.0% vs. 2.5%, p = 0.025). After adjustment, differences for cardiac death and TLR were no longer significant. Conclusions: In the COMBO collaboration, although 1-year TLF was similar regardless of geography, Asians experienced higher rates of cardiac death and lower TLR than Europeans, while incidence of TV-MI and ST was similar in both regions. Adjusted differences did not reach statistical significance. Clinicaltrial.gov identifier-numbers: NCT01874002 (REMEDEE Registry), NCT02183454 (MASCOT registry)
An analysis of the Concept of Freedom and its Implications for Educational Theory and Practice in Egypt, 1805-2000
No full textThe current study attempts to analyse the learners' right to freedom in education in order to determine the nature and content of their education. This analysis will be in relation to the philosophy of education in Egypt to improve the efficiency of the educational system. In this sense the aims of the study can be determined as follows: first to propose a theoretical framework of freedom in education in relation to its meaning, conditions, restrictions and
value, secondly, to develop this theoretical framework of education based on freedom so that it suits Egyptian society, can improve the efficiency of the educational system through the idea of freedom, and thirdly, to identify the difficulties and challenges that might
confront the claim to freedom in education in Egypt.
To achieve these aims the study contains seven chapters, an introduction, a conclusion and appendix that are necessary to achieve its aims and answer its questions. The introduction discusses the general outline of the study and the major issues, questions, aims, methodology and plan of the study. The main aim of chapter one is to analyse the concept of freedom in western and Islamic thought to build a theoretical framework of the meaning of freedom, its conditions and value, which is necessary and important to construct a theoretical framework of the meaning, conditions and value of freedom in education for
learners at school level. Chapter two aims to construct a theoretical framework of freedom in education that will depend on the analysis of the concept of freedom made in chapter one. This analysis will deal with the implications of freedom in education with respect to its conditions, restrictions and value in education. Through this analysis, chapter two aims also to analyse and examine the learners' rights to be free regarding their education. To have a
complete theoretical framework of freedom in education, chapter three discusses other implications with respect to restrictions which might limit learners' freedom by being
subject to state authority.
Chapter four investigates and analyses freedom in educational theory and practice in the history of Egypt from 1805 to 1991, whereas chapter five focuses on the period from 1992 to 2000. Following the analysis of the concept of freedom and its implications in education that will be made in the first five chapters, it would be sensible to construct a framework of educational theory based on freedom that, on one hand, should suite the Egyptian context in chapter six, on the other hand, that guarantees a range of freedom that allows learners and
society derive benefit from its value in education. Having proposed a framework of a theory of education based on freedom that suits the Egyptian context to improve the
efficiency of its educational system chapter seven will discover and examine the conditions and difficulties which need to be considered for the successful implementation of freedom in education. Also, the study will attempt to give some suggestions that might help to reduce the gap between the educational situation, its circumstances and the conditions that must be satisfied for the successful implementation of freedom in education
