151. Mass composition of ultra-high energy cosmic rays at the Pierre Auger ObservatoryGašper Kukec Mezek, 2019, doctoral dissertation Abstract: Cosmic rays with energies above 10^18 eV, usually referred to as ultra-high energy cosmic rays (UHECR), have been a mystery from the moment they have been discovered. Although we have now more information on their extragalactic origin, their direct sources still remain hidden due to deviations caused by galactic magnetic fields. Another mystery, apart from their production sites, is their nature. Their mass composition, still uncertain at these energies, would give us a better understanding on their production, acceleration, propagation and capacity to produce extensive air showers in the Earth's atmosphere. Mass composition studies of UHECR try to determine their nature from the difference in development of their extensive air showers.
In this work, observational parameters from the hybrid detection system of the Pierre Auger Observatory are used in a multivariate analysis to obtain the mass composition of UHECR. The multivariate analysis (MVA) approach combines a number of mass composition sensitive variables and tries to improve the separation between different UHECR particle masses. Simulated distributions of different primary particles are fitted to measured observable distributions in order to determine individual elemental fractions of the composition. When including observables from the surface detector, we find a discrepancy in the estimated mass composition between a mixed simulation sample and the Pierre Auger data. Our analysis results from the Pierre Auger data are to a great degree independent on hadronic interaction models. Although they differ at higher primary masses, the different models are more consistent, when combining fractions of oxygen and iron. Compared to previously published results, the systematic uncertainty from hadronic interaction models is roughly four times smaller. Our analysis reports a predominantly heavy composition of UHECR, with more than a 50% fraction of oxygen and iron at low energies. The composition is then becoming heavier with increasing energy, with a fraction of oxygen and iron above 80% at the highest energies. Keywords: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, machine learning, multivariate analysis Published in RUNG: 03.04.2019; Views: 5001; Downloads: 187 Full text (17,53 MB) |
152. |
153. Določevanje aktivnosti AChE encima v človeškem serumu z uporabo FIA-TLS metode : Magistrsko deloAndrej Jerkič, 2018, master's thesis Abstract: Acetilholinesteraza (AChE) in butirilholinesteraza (BChE) sta encima, odgovorna za razgradnjo nevrotransmitorja acetilholina oziroma butirilholina. Encima spadata v skupino holinesteraz in imata poleg razgradnje nevrotransmiterjev pomembno vlogo v telesu kot indikatorja za različne bolezni ter zastrupitve z organofosfati in drugimi kemikalijami.
Cilji magistrskega dela so razviti občutljivo metodo za določevanje aktivnosti AChE encima v človeškem serumu, določiti celokupno aktivnost AChE ter BChE encimov v vzorcih človeškega seruma neznanih pacientov z uporabo FIA-TLS tehnike ter izmeriti aktivnost AChE v človeškem serumu z uporabo inhibitorja BChE. Opravili smo meritve kinetike pretvorbe acetiltioholina v 5-tio-2-nitrobenzoat (TNB), na podlagi katerih smo izračunali specifično aktivnost AChE encima in aktivnosti različnih njegovih redčitev ter izvedli spektralno karakterizacijo proučevanih vzorcev. Vzorce AChE encima smo pripravili v raztopini 5,5'DITIO-bis (2-nitrobenzoični) kislini (reagent) in raztopini acetiltioholin jodida (substrat). Ugotovili smo, da je absorpcijski vrh za raztopine AChE pri valovni dolžini približno 412 nm. Z meritvami absorpcijskega spektra različnih redčitev AChE smo ugotovili, da absorbanca hitreje narašča v vzorcih z višjo koncentracijo AChE, ker se je povečevala aktivnost encima. Ugotovili smo tudi, da z nižanjem molarnosti DTNB iz 0,50 mM na 0,05 mM lahko znižamo LOD metode zaradi znižanja vrednosti signala slepega vzorca. Tega ne moremo trditi pri znižanju koncentracije DTNB iz 0,05 mM na 0,025 mM zaradi nepopolne reakcije med acetilholinom (ACh), 5-tio-2-nitrobenzoatom (TNB) in acetilholinesterazo (AChE). Metodo FIA-TLS smo optimizirali z uporabo daljše mešalne zanke ter s povečanjem moči vzbujevalnega žarka. Z optimizacijo FIA-TLS sistema nam je uspelo izmeriti vrednosti TLS signala vzorcev z nižjo koncentracijo AChE encima (70 μV) v primerjavi z neoptimiziranim TLS sistemom (110 μV). Izračunana vrednost LOD UV-Vis metode znaša 3,6 mU/ml, medtem ko za FIA-TLS metodo znaša 0,6 mU/ml. V prvem sklopu meritev smo izmerili 14 vzorcev krvnega seruma. Aktivnosti celotne ChE v teh vzorcih znašajo med 2118 mU/ml in 15172 mU/ml, povprečna aktivnost BChE in AChE v vzorcih znaša 4561 mU/ml, mediana meritev pa znaša 2964 mU/ml. V drugem sklopu meritev smo merili 19 vzorcev krvnega seruma z in brez dodatka BChE inhibitorja. Aktivnosti vzorcev brez BChE inhibitorja (celotne ChE) znašajo med 1642 mU/ml in 5958 mU/ml s povprečno vrednostjo 2910 mU/ml in mediano 2228 mU/ml, medtem ko aktivnosti istih vzorcev z dodanim inhibitorjem (samo AChE) znašajo od 519 mU/ml do 1118 mU/ml s povprečno vrednostjo 822 mU/ml in mediano 816 mU/ml. Po dodatku BChE se je aktivnost ChE v vzorcih v povprečju zmanjšala za 3,5-krat oziroma od 55 % do 85 %. Keywords: Acetilholinesteraza, butirilholinesteraza, FIA-TLS, aktivnost AChE encima, inhibicija BChE encima Published in RUNG: 30.11.2018; Views: 4771; Downloads: 174 Full text (2,51 MB) |
154. Efficient traffic regulation based on urban Black Carbon measurements and prediction modelAsta Gregorič, Luka Drinovec, Griša Močnik, Anja Barle, Matija Marolt, Jernej Henigman, Borut Šuštar, Mitja Ferlan, Andrej Pangeršič, 2018, published scientific conference contribution abstract Keywords: air quality, black carbon Published in RUNG: 29.10.2018; Views: 3666; Downloads: 0 This document has many files! More... |
155. Rapid and Sensitive Determination of ChE Activity in Blood PlasmaAndrej Jerkič, Tjaša Birsa, Mojca Žorž, Dorota Korte, Martina Bergant Marušič, Mladen Franko, 2018, published scientific conference contribution abstract Keywords: flow injection analysis, thermal lens spectrometric detection, acetylcholinesterase, butyrylcholinesterase, enzyme activity Published in RUNG: 16.07.2018; Views: 4369; Downloads: 0 This document has many files! More... |
156. Esej na maturi 2019Zoran Božič, Adrijana Špacapan, Andrej Adam, professional monograph Abstract: Didaktična predstavitev romanov Francoski testament in Angel pozabe (tematski sklop za pisanje eseja iz slovenščine na splošni maturi 2019). Keywords: didaktika, francoska književnost, Andrei Makine, roman, slovenska književnost, avstrijska književnost, Maja Haderlap, Zoran Božič, Adrijana Špacapan, druga svetovna vojna, prva svetovna vojna, nemška taborišča, ruski gulagi, partizanski odpor, posledice vojne, narodna manjšina, nacizem, stalinizem, diktatura, Pariz Published in RUNG: 04.06.2018; Views: 5695; Downloads: 0 This document has many files! More... |
157. Speciation and Determination of Ionic and Trace-Level Colloidal Silver in Selected Personal Care Products by Thermal Lens SpectrometryDorota Korte, Ales Grahovac, Andrej Jerkic, Olga Vajdle, Jasmina Anojčić, Valeria Guzsvány, Bojan Budič, Mladen Franko, 2018, original scientific article Keywords: Silver nanoparticles, Colloidal silver, Personal care
products, Thermal lens spectrometric determination, Flow injection
analysis Published in RUNG: 26.02.2018; Views: 4268; Downloads: 0 This document has many files! More... |
158. All-sky search for correlations in the arrival directions of astrophysical neutrino candidates and ultrahigh-energy cosmic raysI. Al Samarai, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: correlations, astrophysical neutrino, ultrahigh-energy cosmic rays Published in RUNG: 19.02.2018; Views: 3509; Downloads: 166 Full text (3,07 MB) |
159. Testing the agreement between the Xmax distributions measured by the Pierre Auger and Telescope Array ObservatoriesV. De Souza, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: Xmax distributions, Pierre Auger Observatory, Telescope Array Published in RUNG: 19.02.2018; Views: 3802; Downloads: 179 Full text (266,09 KB) |
160. Report of the Telescope Array - Pierre Auger Observatory Working Group on Energy SpectrumDmitri Ivanov, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Darko Veberič, Serguei Vorobiov, Marta Trini, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: Telescope Array, Pierre Auger Observatory, Energy Spectrum Published in RUNG: 19.02.2018; Views: 3434; Downloads: 172 Full text (398,98 KB) |