761 research outputs found
The impact of distance learning on high school students in Slovenia
No full textS prednostmi tehnologije moderne družbe smo se bili zmožni spopasti z izredno situacijo, ki jo je povzročila kriza koronavirusa. Prisilno zaprtje šol sredi šolskega leta je presenetilo tako učitelje kot tudi učence, ki so se morali poleg številnih drugih prilagoditev vpeljati tudi v izobraževanje na daljavo. Slednje zahteva drugačno pripravo in načrtovanje, oblike in metode, kar smo opisali v teoretičnem delu magistrske naloge. Podrobneje smo opisali tudi pomembnost učne individualizacije in motivacije ter slednji primerjali s tem, kako potekata v razredu in kako na daljavo. Ne nazadnje pa smo opisali tudi zaznavne učne stile ter usklajevanje le-teh z oblikami poučevanja in to primerjali z izobraževanjem, ki poteka v razredu ter na daljavo.
V empiričnem delu smo izvedli raziskavo s pomočjo anonimnega vprašalnika. Naš glavni namen je bil ugotoviti, kakšne so bile posledice izobraževanje na daljavo na srednješolce, katere oblike poučevanja na daljavo so izbrali profesorji ter ali so le-te vplivale na uspeh dijakov z različnimi zaznavnimi učnimi stili.
Na podlagi odgovorov smo rezultate interpretirali in ugotovili, da se vizualni in bralno-pisni zaznavni učni stil ter slušne in gibalne oblike poučevanja razlikujejo glede na letnik, ki ga obiskujejo dijaki. Ugotovili smo tudi, da je poučevanje na daljavo vplivalo na uspešnost dijakov ter da se le-ta razlikuje glede na letnik pri predmetih biologija in geografija. Spoznali smo, da vizualni, slušni in gibalni zaznavni učni stil vplivajo na uspešnost dijakov pri družboslovnih in naravoslovnih predmetih zaradi izobraževanja na daljavo, medtem ko bralni zaznavni učni stil vpliva le na uspeh pri družboslovnih predmetih. Prav tako smo ugotovili, da oblike poučevanja na daljavo ne vplivajo na uspešnost dijakov.The advantages of technology provided by contemporary society have enabled us to successfully tackle the extraordinary situation caused by the coronavirus crisis. The forced closures of schools in the middle of the school year proved a surprising development for both teachers and students who not only had to adapt to the situation at hand in various other ways but also introduce distance learning which requires different preparation and planning, forms and methods as described in the theoretical part of the Master’s thesis. In addition, the thesis contains a detailed description of the significance of learning individualisation and motivation and a comparison between them if classes are held in the classroom or online. Last but not least, the thesis also contains a description of the established learning styles and their harmonisation with teaching methods and a comparison between them if classes are held in the classroom or online.
The empirical part contains a survey conducted through an anonymous questionnaire. The main purpose was to identify the effects of distance learning on high school students, the distance learning methods chosen by their professors and whether this impacted the performance of high school students with various established learning styles.
Answers to the questionnaire were used to interpret the obtained results. It was found that the visual and reading-writing established learning styles and auditory and kinesthetic learning styles vary subject to the grade of high school students. It was also found that distance learning did impact the performance of high school students which varies subject to the grade of high school students in Biology and Geography. It was established that the visual, auditory and kinesthetic learning styles impacted the performance of high school students in arts and science as part of the distance learning process whereas the reading established learning style only impacted their performance in arts. It was also found that various teaching methods during the distance learning process did not have any impact on the performance of high school students
Promotion of the University of Maribor Botanical Garden Using Social Media
No full textV diplomskem projektu obravnavamo družbene medije kot orodje za promocijo Botaničnega vrt Univerze v Mariboru, pri čimer smo se osredotočili na uporabo obstoječih in potencilano primernih brezplačnih omrežiij. S pomočjo določanja segmentov povpraševanja smo definirali medije, s katerimi bi bilo smiselno oglaševati posamezni segment ter analizirali, v kolikšni meri je poleg oglaševanja preko družbenih medijev potrebno tudi komuniciranje s pomočjo klasičnih medijev. S SWOT analizo smo predstavili trenutno stanje oglaševanja z družbenimi mediji in z mednarodno primerjavo promocije tovrstne ponudbe ocenili, kako bi lahko v Botaničnem vrtu Univerze v Mariboru izboljšali način komuniciranja s potencialnimi obiskovalci.In the graduation thesis we are discussing social media as a promotion tool of the University of Maribor Botanical Garden. We are focusing on the existing and potentially relevant free networks. After identifying demand segments, we defined which media would suit best to reach the individual segments. We also analyzed wheather the need of using classic media existed. Using the SWOT analysis, we evaluated the state of the act of advertisingthat uses social media. By the means of an international comparison of the social media use in promotion in some chosen Botanical Gardens aboard, we formulated the conclusions on how the University of Maribor Botanical Garden can be improved
Toward a tomographic analysis of the cross-correlation between planck cmb lensing and h-atlas galaxies
No full textINAF PRIN; ASI/INAF [2014-024-R.0]; INFN-INDARK initiative; Spanish MINECOBianchini, F., Lapi, A., Calabrese, M., Bielewicz, P., Gonzalez-Nuevo, J., Baccigalupi, C., Danese, L., Zotti, G.D., Bourne, N., Cooray, A., Dunne, L., Eales, S., Valiante, E
The astrophysics of the intracluster plasma
No full textSince 1971 observations in X rays of several thousands of galaxy clusters have uncovered huge amounts of hot baryons filling up the deep gravitational potential wells provided by dark matter (DM) halos with masses of some 1015 M&sun; and sizes of millions of light-years. At temperatures T~108 K and with average densities of n~1 particle per liter, such baryons add up to some 1014 M&sun;. With the neutralizing electrons, they constitute the best proton-electron plasma in the Universe (whence the apt name Intra Cluster Plasma, ICP), one where the thermal energy per particle overwhelms the electron-proton Coulomb interaction by extralarge factors of order 1012. The ICP shines in X rays by thermal bremsstrahlung radiation, with powers up to several 1045erg s-1 equivalent to some 1011 solar luminosities. The first observations were soon confirmed in X rays by the detection of high excitation emission lines, and in the radio band by studies of streamlined radiogalaxies moving through the ICP. Later on they were nailed down by the first measurements in microwaves of the Sunyaev-Zel'dovich effect, i.e., the inverse Compton upscattering of cold cosmic background photons at T≈2.73 K off the hot ICP electrons at kBT~5 keV. A key physical feature of the ICP is constituted by its good local thermal equilibrium, and by its overall hydrostatic condition in the DM wells, modulated by entropy. The latter is set up in the cluster center by the initial halo collapse, and is progressively added at the outgrowing cluster boundary by standing shocks in the supersonic flow of intergalactic gas into the DM potential wells. Such physical conditions are amenable to detailed modeling. We review here these entropy-based models and discuss their outcomes and predictions concerning the ICP observables in X rays and in microwaves, as well as the underlying DM parameters. These quantitative outcomes highlight the tight relationship between the detailed ICP profiles and the cosmological evolution of the containing DM potential wells. The results also provide the simplest baseline for disentangling a number of additional and intriguing physical processes superposed to the general equilibrium. The present Report is focused on the ICP physics as driven by the two-stage evolution of the containing DM halos. We extensively discuss the basic entropy pattern established by the cluster formation and development, and cover: the central entropy erosion produced by radiative cooling that competes with the intermittent energy inputs due to active galactic nuclei and mergers; outer turbulent support linked with weakening shocks and decreasing inflow through the virial boundary, causing reduced entropy production during the late stage of DM halo evolution; the development from high to low entropy levels throughout a typical cluster; perturbations of the equilibrium up to outright disruption due to deep impacts of infalling galaxy groups or collisions with comparable companion clusters; relativistic energy distributions of electrons accelerated during such events, producing extended radio emission by synchrotron radiation and contributing non thermal pressure support for the ICP. We conclude with discussing selected contributions from cluster astrophysics to cosmology at large, and by addressing how the ICP features and processes will constitute enticing targets for observations with the ongoing Planck mission, for upcoming instrumentation like ALMA and other ground-based radio observatories, and for the next-generation of X-ray satellites from ASTRO-H to eROSITA
Herschel-ATLAS : deep HST/WFC3 imaging of strongly lensed submillimetre galaxies
No full textThis work is supported by STFC (grants PP/D002400/1 and ST/G002533/1)We report on deep near-infrared observations obtained with the Wide Field Camera-3 (WFC3) onboard the Hubble Space Telescope (HST) of the first five confirmed gravitational lensing events discovered by the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). We succeed in disentangling the background galaxy from the lens to gain separate photometry of the two components. The HST data allow us to significantly improve on previous constraints of the mass in stars of the lensed galaxy and to perform accurate lens modelling of these systems, as described in the accompanying paper by Dye et al. We fit the spectral energy distributions of the background sources from near-IR to millimetre wavelengths and use the magnification factors estimated by Dye et al. to derive the intrinsic properties of the lensed galaxies. We find these galaxies to have star-formations rates (SFR) ∼ 400–2000 M⊙ yr−1, with ∼(6–25) × 1010 M⊙ of their baryonic mass already turned into stars. At these rates of star formation, all remaining molecular gas will be exhausted in less than ∼100 Myr, reaching a final mass in stars of a few 1011 M⊙. These galaxies are thus proto-ellipticals caught during their major episode of star formation, and observed at the peak epoch (z ∼ 1.5–3) of the cosmic star formation history of the Universe.Peer reviewe
Structure and history of dark matter halos probed with gravitational lensing
No full textWe test with gravitational lensing (GL) data the dark matter (DM) halos embedding the luminous baryonic component of galaxy clusters; our benchmark is provided by their two-stage cosmogonical development that we compute with its variance, and by the related "α-profiles" we derive. The latter solve the Jeans equation for the self-gravitating, anisotropic DM equilibria, and yield the radial runs of the density ρ(r) and the velocity dispersion σ2 r (r) in terms of the DM "entropy" K ≡ σ2 r /ρ2/3 r α highlighted by recent N-body simulations; the former constrains the slope to the narrow range α 1.25-1.3. These physically based α-profiles meet the overall requirements from GL observations, being intrinsically flatter at the center and steeper in the outskirts relative to the empirical Navarro, Frenk, & White formula. Specifically, we project them along the line of sight and compare with a recent extensive data set from strong and weak lensing observations in and around the cluster A1689. We find an optimal fit at both small and large scales in terms of a halo constituted by an early body with α 1.25 and by recent extensive outskirts, that make up an overall mass 1015 M ☉ with a concentration parameter c 10 consistent with the variance we compute in the ΛCDM cosmogony. The resulting structure corresponds to a potential well shallow in the outskirts as that inferred from the X rays radiated from the hot electrons and baryons constituting the intracluster plasma
Supermodel Analysis of the Hard X-ray Excess in the Coma Cluster
No full textThe Supermodel (SM) provides an accurate description of the thermal contribution by the hot intracluster plasma which is crucial for the analysis of the hard excess. In this paper, the thermal emissivity in the Coma cluster is derived starting from the intracluster gas temperature and density profiles obtained by the SM analysis of X-ray observables: the XMM-Newton temperature profile and the ROSAT brightness distribution. The SM analysis of the BeppoSAX/Phoswich Detector System (PDS) hard X-ray (HXR) spectrum confirms our previous results, namely, an excess at the confidence level (c.l.) of ~4.8σ and a nonthermal (NT) flux of (1.30 ± 0.40) × 10–11 erg cm–2 erg cm–1 in the energy range 20-80 keV. A recent joint XMM-Newton/Suzaku analysis reports an upper limit of ~6 × 10–12 erg cm–2 erg cm–1 in the energy range 20-80 keV for the NT flux with an average gas temperature of 8.45 ± 0.06 keV and an excess of NT radiation at a c.l. above 4σ, without including systematic effects, for an average XMM-Newton temperature of 8.2 keV in the Suzaku/HXD-PIN FOV, in agreement with our earlier PDS analysis. Here we present a further evidence of the compatibility between the Suzaku and BeppoSAX spectra, obtained by our SM analysis of the PDS data, when the smaller size of the HXD-PIN FOV and the two different average temperatures derived by XMM-Newton and by the joint XMM-Newton/Suzaku analysis are taken into account. The consistency of the PDS and HXD-PIN spectra reaffirms the presence of an NT component in the HXR spectrum of the Coma cluster. The SM analysis of the PDS data reports an excess at c.l. above 4σ also for the higher average temperature of 8.45 keV thanks to the PDS FOV being considerably greater than the HXD-PIN FOV
Dark Matter Equilibria in Galaxies and Galaxy Systems
No full textIn the dark matter (DM) halos embedding galaxies and galaxy systems the "entropy" K ≡ σ2/ρ2/3 (a quantity that combines the radial velocity dispersion σ with the density ρ) is found from intensive N-body simulations to follow a power-law run K vprop r α throughout the halos' bulk, with α around 1.25. Taking up from phenomenology just that α≈ const. applies, we cut through the rich analytic contents of the Jeans equation describing the self-gravitating equilibria of the DM; we specifically focus on computing and discussing a set of novel physical solutions that we name α-profiles, marked by the entropy slope α itself, and by the maximal gravitational pull κcrit(α) required for a viable equilibrium to hold. We then use an advanced semianalytic description for the cosmological buildup of halos to constrain the values of α to within the narrow range 1.25-1.29 from galaxies to galaxy systems; these correspond to halos' current masses in the range 1011-1015 M sun. Our range of α applies since the transition time that—both in our semianalytic description and in state-of-the-art numerical simulations—separates two development stages: an early violent collapse that comprises a few major mergers and enforces dynamical mixing, followed by smoother mass addition through slow accretion. In our range of α we provide a close fit for the relation κcrit(α), and discuss a related physical interpretation in terms of incomplete randomization of the infall kinetic energy through dynamical mixing. We also give an accurate analytic representation of the α-profiles with parameters derived from the Jeans equation; this provides straightforward precision fits to recent detailed data from gravitational lensing in and around massive galaxy clusters, and thus replaces the empirical Navarro-Frenk-White formula relieving the related problems of high concentration and old age. We finally stress how our findings and predictions as to α and κcrit contribute to understanding hitherto unsolved issues concerning the fundamental structure of DM halos
Coordination of the Co2+and Ni2+Ions in Tf2N-Based Ionic Liquids: A Combined X-ray Absorption and Molecular Dynamics Study
No full textMolecular dynamics (MD) simulations and X-ray absorption spectroscopy (XAS) have been combined to study the coordination of the Co2+ and Ni2+ ions in ionic liquids (ILs) based on the bis(trifluoromethylsulfonyl)imide ([Tf2N]-) anion and having different organic cations, namely, 1-butyl-3-methylimidazolium ([C4mim]+), 1,8-bis(3-methylimidazolium-1-yl)octane ([C8(mim)2]2+), N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium ([choline]+), and butyltrimethylammonium ([BTMA]+). Co and Ni K-edge XAS data have been collected on 0.1 mol L-1 Co(Tf2N)2 and Ni(Tf2N)2 solutions and on the metallic salts. MD simulations have been carried out to obtain structural information on the metal ion coordination. The analysis of the extended X-ray absorption fine structure (EXAFS) spectra of the solutions has been carried out based on the atomistic description provided by MD, and the studied ILs have been found to be able to dissolve both the Co(Tf2N)2 and Ni(Tf2N)2 salts giving rise to a different structural arrangement around the metal ions as compared to the solid state. The combined EXAFS and MD results showed that the Co2+ and Ni2+ ions are surrounded by a first solvation shell formed by six [Tf2N]- anions, each coordinating in a monodentate fashion by means of the oxygen atoms. The nature of the IL organic cation has little or no influence on the overall spatial arrangement of the [Tf2N]- anions, so that stable octahedral complexes of the type [M(Tf2N)6]4- (M = Co, Ni) have been observed in all the investigated ILs
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