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Abstract: Fascinating packing patterns of identical spherical and discotic objects on curved surfaces occur readily in nature and science. Examples include C60 fullerenes,(1, 2)13-atom cuboctahedral metal clusters,(3) and S-layer proteins on outer cell membranes.(4) Numerous situations with surface-arranged objects of variable size also exist, such as the lenses on insect eyes, biomineralized shells on coccolithophorids,(5) and solid-stabilized emulsion droplets(6) and bubbles.(7) The influence of size variations on these packing patterns, however, is studied sparsely. Here we investigate the packing of nanosized silica particles on the surface of polystyrene latex particles fabricated by Pickering miniemulsion polymerization of submicrometer-sized armored monomer droplets. We are able to rationalize the experimental morphology and the nearest-neighbor distribution with the help of Monte Carlo simulations. We show that broadening of the nanoparticle size distribution has pronounced effects on the self-assembled equilibrium packing structures, with original 12-point dislocations or grain-boundary scars gradually fading out.
Found in: ključnih besedah
Keywords: packing patterns, silica, simulation, Monte Carlo, order, disorder, transition, armored particles, nanoparticles, Pickering emulsion
Published: 10.10.2016; Views: 3881; Downloads: 0
Fulltext (3,85 MB)

Found in: ključnih besedah
Summary of found: ...of particle physics models of dark matter particles. In particular, experiments such as Fermi -LAT,...
Keywords: We live in a golden age for astro-particle physics, with a significant number of experiments actively monitoring high-energy Universe. Many of these probes provide excellent tests of particle physics models of dark matter particles. In particular, experiments such as Fermi -LAT, AMS-02, Ice Cube, ... are significantly cutting into the parameter space of one of the most popular candidates, the WIMPs. In this talk I will describe some of the strategies and methods used to search for dark matter with astrophysical data. Special attention will be given to the latest indications of an unaccounted gamma-ray excess at few GeV in the Fermi-LAT data in the region around the Galactic Centre, which steered lots of attention as it was shown to be consistent with putative signals of WIMP dark matter particles and complementary constraints provided by other experiments. Finally I will discuss projections of the expected sensitivities with upcoming experiments and continued data taking with current ones.
Published: 17.07.2017; Views: 3974; Downloads: 0
Fulltext (50,35 MB)

Abstract: In spite of the successes of observational astro- and particle physics and cosmology very much of the universe remains unknown. The Standard Model of particle physics is a theory describing the electromagnetic, weak, and strong nuclear interactions, as well as classifying all the subatomic particles known. But there is overwhelming evidence, that all the known particles, the ordinary (baryonic) matter, the building blocks of planets, stars and ourselves, only make up about 4.9% of the energy content of the universe. The standard model of cosmology (CDM) indicates that the total mass-energy of the universe contains beside the 4.9% ordinary matter two other components: 26.8% dark matter and 68.3% dark energy. The accelerating expansion of the Universe is the result of the effect of the dark energy with its most simple form given by a cosmological constant in Einstein's Equation. Dark matter is an unidentified type of matter that is not accounted for by dark energy and neutrinos and is generally believed to be a non-relativistic, charge neutral and non-baryonic new form of matter. Although dark matter has not been directly observed yet, its existence and properties are inferred from its gravitational effects such as the motions of visible matter, gravitational lensing, its influence on the universe's large-scale structure, and its effects in the cosmic microwave background. Thus the search for Dark Matter is the search for physics beyond the standard model. Although the nature of dark matter is yet unknown, its presence is crucial to understanding the future of the universe. The CRESST experiment is searching for direct evidence in the form of a nuclear recoil induced on a scintillating CaWO4 crystal by a dark matter particle, and is installed and taking data underground at Laboratory Nazionali del Gran Sasso (LNGS) in Italy. While both, dark energy and dark matter, have not been detected directly, a class of dark matter particles that interact only via gravity and the weak force, referred to asWeakly Interacting Massive Particles (WIMPs), has been established as the leading candidate among the dark matter community. For this thesis a special model of dark matter was studied, namely the dark photon. This thesis provides a detailed description of the calculation of the 90% upper limit on the dark photon kinetic mixing based on data from the second phase of the CRESST experiment. The analysis was carried out in a frequentist approach based on the (unbinned) maximum-likelihood method and likelihood ratios. To make a statement about the calculated result and its quality, the used algorithm had to be tested, what was done with Monte Carlo simulations (pseudo data).
Found in: ključnih besedah
Summary of found: ...as well as classifying all the subatomic particles known. But there is overwhelming evidence, that...
Keywords: astro physics, particle physics, cosmology, universe, Standard Model of particle physics, standard model of cosmology, matter, ordinary matter, dark matter, dark energy, accelerating expansion of the Universe, non-baryonic, new form of matter, gravitational lensing, cosmic microwave background, search for physics beyond the standard model, CRESST experiment, direct detection, CaWO4 crystal, underground laboratory, Laboratory Nazionali del Gran Sasso, Weakly Interacting Massive Particles, WIMP, dark photon, 90% upper limit, upper limit, kinetic mixing, frequentist approach, unbinned, maximum likelihood
Published: 13.10.2017; Views: 3625; Downloads: 0
Fulltext (10,71 MB)

Found in: ključnih besedah
Summary of found: ...Nano particles anisotropic particles magnetic nanocompoistes topological insulator...
Keywords: Nanoparticles anisotropic particles magnetic nanocompoistes topological insulator
Published: 05.11.2018; Views: 2607; Downloads: 0
Fulltext (97,20 KB)

Abstract: In this paper, we discuss examples of sluicing in Slovenian in which, in addition to a wh-phrase (or wh-phrases in instances of multiple sluicing) discourse particles appear. This is unexpected given Merchant’s (2001) Sluicing-COMP generalization, as already observed in Marušič et al. (2015), even though there are several languages in which similar cases exist, e.g. German. In this paper we focus on discourse particles pa and že in (multiple) wh-questions and sluicing. These examples are not only important for our understanding of sluicing but are also crucial for analyzing discourse particles in Slovenian. Based on examples with sluicing and discourse particles in Slovenian, we argue against positioning these particles within the whphrase, clitic cluster or the IP.
Found in: ključnih besedah
Summary of found: ...wh-phrases in instances of multiple sluicing) discourse particles appear. This is unexpected given Merchant’s (2001)...
Keywords: Slovenian, sluicing, particles, sluicing-COMP generalization
Published: 01.02.2019; Views: 2799; Downloads: 0
Fulltext (164,52 KB)