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11 - 19 / 19
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11.
Diurnal cycling of urban aerosols under different weather regimes
Janja Vaupotič, Maja Remškar, Griša Močnik, Luka Drinovec, Asta Gregorič, Samo Stanič, 2016, published scientific conference contribution abstract

Found in: osebi
Keywords: kakovost zraka, črn ogljik, aerosoli
Published: 03.05.2016; Views: 2047; Downloads: 141
.pdf Fulltext (33,73 KB)

12.
THE ROLE OF SPECT/CT SCINTIGRAPHY IN LOCALIZATION OF PARATHYROID ADENOMAS
Sebastijan Rep, 2016, master's thesis

Abstract: Parathyroid scintigraphy is based on the different accumulation and distribution of radiopharmaceutical 99mTc-MIBI (MIBI) in parathyroid and adjacent tissues. Different scintigraphic techniques can be used: subtraction scintigraphy is a combination of MIBI and 99mTc-pertehnetate (pertehnetate) scintigraphy; SPECT can be performed after intravenous injection of MIBI or in the combination with low-dose computerized tomography (SPECT/CT) which allows precise anatomical localization of enlarged parathyroid glands (EPG). The objectives of our study were: to assess diagnostic performance of preoperative localization of EPG (adenomas and hyperplasia) of the early, delayed and combined SPECT/CT and of subtraction scintigraphy in patients with biochemically proven primary hyperparathyroidism (PHP); to determine whether size of EPG, serum parathyroid hormone (PTH), calcium (Ca) and phosphate (P) correlate with successful localization; to assess radiation exposure of patients with early and late SPECT/CT and subtraction scintigraphy The study included 41 patients in whom early, delay SPECT/CT and subtraction scintigraphy were performed. For all scintigraphic methods sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated. Receiver Operating Characteristic analysis was used to express relationship between scintigraphy results and size of the EPG and serum Ca, P and PTH levels. ImPACT CT Patient Dosimetry Calculator and weighting factors for radiopharmaceuticals (MIBI and pertechnetate) were used for calculating patient expose dose. Sensitivity and specificity were 51.1% and 98.3 for subtraction scintigraphy, 65.1% and 97.5% for early SPECT/CT and 65.1% and 95.5% for delay SPECT/CT. In combined early and delay SPECT/CT sensitivity and specificity were 74.4% and 95.1%.Only size of the EPG correlated with successful localization in our study (AUC of 0.791-0.810). The highest average ED per patient had subtraction scintigraphy (7.37±0.40 mSv), which was statistically significant higher in comparison to combined early and delayed SPECT/CT (6.81±0.44 mSv). The most sensitive and most accurate method of preoperative localization of EPG in patients with PHP is combined early and delayed SPECT/CT. Only size of the EPG correlates with successful localization. The highest radiation exposure is after subtraction scintigraphy.
Found in: osebi
Keywords: Enlarged parathyroid glands, early SPECT/CT, delayed SPECT/CT, combined SPECT/CT, subtraction scintigraphy, 99mTc-MIBI, 99mTc-pertechnetate, effective dose, serum parathyroid hormone, calcium, phosphate
Published: 03.10.2016; Views: 3061; Downloads: 150
.pdf Fulltext (1,03 MB)

13.
ASSESSMENT OF EFFECTIVE DOSES BASED ON VARIOUS RADON MEASURING TECHNIQUES
Nataša Smrekar, 2016, master's thesis

Abstract: In my master's thesis, I have focused on radon gas in 43 buildings used for different purposes (23 schools, 3 kindergartens, 16 offices and a residential house) in which preliminary measurements had shown higher concentrations of radon gas. I carried out measurements of radon and short-lived radon products whilst simultaneously employing different measurement techniques. In all 43 buildings, I measured the instantaneous concentration of radon by using scintillation cells; in 18 buildings, I additionally measured the average concentration of radon by using solid state nuclear track detectors and in 10 buildings, I measured concentration retrospectively with solid state nuclear track detectors. In four selected buildings (a school, a kindergarten, an office and a residential house), I carried out the measurements by using all of the available equipment. I monitored the daily fluctuations of concentration of radon and short-lived radon products by using continuous monitors in 14 buildings. This is how I obtained the factor of radioactive equilibrium between radon and its short-lived products. Based on the results obtained, I calculated the effective doses. As the basis for calculating the doses, I used the instantaneous and average concentrations of radon and the equilibrium factor taken from literature (0.40) or own measurements. I compared the doses and critically evaluated them. In contrast to the previous research, I researched radon exclusively in areas with increased risk for radon. I studied the influence of the working regime on the concentration of radon in different working environments (i.e. a school, a kindergarten and an office).
Found in: osebi
Keywords: Radon, short-lived radon products, measurement technique, scintillation cell, solid-state nuclear track detector, retrospective detector, equilibrium factor, effective dose, comparison.
Published: 28.09.2016; Views: 2540; Downloads: 188
.pdf Fulltext (1,86 MB)

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Retrieval of Vertical Mass Concentration Distributions—Vipava Valley Case Study
Miloš Miler, Janja Vaupotič, Luka Drinovec, Griša Močnik, William Eichinger, Klemen Bergant, Samo Stanič, Longlong Wang, Mateja Gosar, Asta Gregorič, 2019, original scientific article

Abstract: Aerosol vertical profiles are valuable inputs for the evaluation of aerosol transport models, in order to improve the understanding of aerosol pollution ventilation processes which drive the dispersion of pollutants in mountainous regions. With the aim of providing high-accuracy vertical distributions of particle mass concentration for the study of aerosol dispersion in small-scale valleys, vertical profiles of aerosol mass concentration for aerosols from different sources (including Saharan dust and local biomass burning events) were investigated over the Vipava valley, Slovenia, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. The analysis was based on datasets taken between 1–30 April 2016. In-situ measurements of aerosol size, absorption, and mass concentration were combined with lidar remote sensing, where vertical profiles of aerosol concentration were retrieved. Aerosol samples were characterized by SEM-EDX, to obtain aerosol morphology and chemical composition. Two cases with expected dominant presence of different specific aerosol types (mineral dust and biomass-burning aerosols) show significantly different aerosol properties and distributions within the valley. In the mineral dust case, we observed a decrease of the elevated aerosol layer height and subsequent spreading of mineral dust within the valley, while in the biomass-burning case we observed the lifting of aerosols above the planetary boundary layer (PBL). All uncertainties of size and assumed optical properties, combined, amount to the total uncertainty of aerosol mass concentrations below 30% within the valley. We have also identified the most indicative in-situ parameters for identification of aerosol type.
Found in: osebi
Keywords: valley air pollution, aerosol vertical distributions, lidar remote sensing, in-situ measurements, aerosol identification
Published: 09.01.2019; Views: 990; Downloads: 31
.pdf Fulltext (7,43 MB)

17.
Determination of source specific black carbon and CO2 emission rates by means of 222Rn tracer
Asta Gregorič, Luka Drinovec, Irena Ježek, Janja Vaupotič, Griša Močnik, 2019, published scientific conference contribution abstract

Found in: osebi
Keywords: black carbon emission, radon
Published: 17.07.2019; Views: 428; Downloads: 0
.pdf Fulltext (13,70 MB)

18.
Odvisnost koncentracije nanodelcev v zunanjem zraku od stabilnosti atmosfere
Anja Petra Bencek, 2019, master's thesis

Abstract: Nanodelci v zraku škodljivo vplivajo na okolje in na človeka. Še posebej smo jim izpostavljeni v večjih mestih, kjer je njihov glavni izvor promet. Zato smo v zunanjem zraku v Ljubljani merili številčne koncentracije delcev (CN) velikosti 10 – 1083 nm z merilnikom 'Scanning Mobility Particle Sizer' proizvajalca Grimm Aerosol Technik, Nemčija, v vseh letnih časih v letu 2018. Delce smo razvrstili v dve skupini, PM0,1 in PM1,1, in spremljali njihovo odvisnost od stabilnosti atmosfere, ki smo jo določili na osnovi koncentracije radona (222Rn) v zraku. Pozimi in jeseni smo določili šest razredov stabilnosti (R1 – R6), spomladi in poleti pa pet (R1 – R5). Koncentracije delcev smo merili na Institutu "Jožef Stefan", podatke o gostoti prometa pa smo pridobili za Tržaško cesto, ki je oddaljena približno 200 m. Obdobja meritev so bila: (i) 30.12.2017 – 2.1.2018; 20. – 26.1.2018 pozimi, (ii) 12. – 18.4.2018 spomladi, (iii) 9. – 27.7.2018 poleti, in (iv) 5.9. – 6.11.2018 jeseni. Številčne koncentracije delcev so se običajno gibale v naslednjih območjih (v cm–3): (i) 2000 – 20000 PM0,1 in 1000 – 5000 PM1,1 pozimi, (ii) 5000 – 20000 PM0,1 in 1000 – 4000 PM1,1 spomladi, (iii) 1500 – 15000 PM0,1 in 1000 – 3000 PM1,1 poleti, in (iv) 5000 – 20000 PM0,1 in 3000 – 8000 PM1,1 jeseni. V splošnem je koncentracija PM0,1 višja za faktor 2 – 3 od koncentracije delcev PM1,1. Koncentracije delcev PM0,1 so odvisne predvsem od gostote prometa, med delovniki imamo dve izraziti konici, vezani na začetek in zaključek službe, med vikendi so koncentracije približno za polovico nižje. Skozi vse leto so njihove koncentracije v zunanjem zraku podobne, ker pa imajo krajši čas zadrževanja v ozračju, čez dan veliko bolj nihajo kot koncentracije PM1,1. Na koncentracije delcev PM1,1 vpliva promet v manjši meri, nekoliko višje koncentracije so pozimi, spomladi in jeseni, verjetno odraz kurilne sezone. Koncentracije delcev sledijo spremembam v stabilnosti atmosfere, praviloma se višajo z večanjem razreda stabilnosti. Najvišje koncentracije delcev PM1,1 so v razredu R6, to je v času dolgotrajne temperaturne inverzije. Koncentracije delcev PM0,1 se manj ujemajo z razredi stabilnosti.
Found in: osebi
Keywords: Nanodelec, PM1, 1 in PM0, 1, radon, stabilnost atmosfere, kontinuirna meritev, letni čas, Ljubljana
Published: 14.10.2019; Views: 537; Downloads: 33
.pdf Fulltext (4,92 MB)

19.
Vpliv bivalnih navad na dinamiko radona v domovih
Monika Ferfolja, 2019, master's thesis

Abstract: Radioaktiven žlahtni plin radon (222Rn) je eden izmed največjih onesnaževalcev zraka v zaprtih prostorih, saj lahko vsakodnevna izpostavljenost radonu vodi do nastanka pljučnega raka. Cilj magistrske naloge je bil ugotoviti, kako bivalne navade stanovalcev (predvsem prezračevanje) vplivajo na koncentracije aktivnosti radona v prostorih in na prejete efektivne doze. V mestu Idrija smo si izbrali dve hiši (H1 in H2), ki stojita v bližini Idrijske prelomnice, kjer smo primerjali dinamiko radona v povezavi z bivalnimi navadami. Najprej smo v obeh hišah izmerili trenutne koncentracije radona v več prostorih. Nato smo na osnovi trenutne koncentracije radona izbrali prostor z enako namembnostjo in čim bolj podobno koncentracijo radona za nadaljnje kontinuirne meritve. Izkazalo se je, da sta to spalnici obeh hiš, kjer so se trenutne koncentracije radona razlikovale le za 1 %. Kontinuirne meritve radona smo v obeh spalnicah izvedli v obdobju od 1.1. do 18.11.2018. Iz urnih koncentracij radona smo izračunali različna povprečja koncentracij: letno, dnevno, zimsko, spomladansko, poletno in jesensko, in jih uporabili za izračun efektivnih doz, ki jih prejmejo stanovalci v času spanja (8 od 24 ur za vse leto). Povprečne koncentracije radona samo poleti niso presegle mejne vrednosti 300 Bq m─3. Po pričakovanju so bile v obeh spalnicah koncentracije radona najvišje pozimi in najnižje poleti, spomladi in jeseni pa so bile precej podobne. Koncentracije so bile višje ponoči kot podnevi, v vseh letnih časih pa najvišje zjutraj, pred začetkom zračenja spalnic. V spalnici H1 je bila povprečna letna koncentracija radona 797754 Bq m─3, v spalnici H2 pa 854785 Bq m─3. Efektivne doze smo izračunali na osnovi koncentracije aktivnosti radona za (i) ves dan (0─24h) in (ii) samo nočni čas (22─6h). Povprečna letna celodnevna (0─24h) efektivna doza je bila v spalnici H1 8,83 mSv in v spalnici H2 9,52 mSv. Povprečna letna nočna (22─6h) efektivna doza pa je bila v spalnici H1 višja za faktor 1,03 in v spalnici H2 za faktor 1,07 od celodnevne. Efektivne doze so v obeh spalnicah močno povezane s prezračevanjem, saj se z večjo intenzivnostjo zračenja znižajo. Tako je efektivna doza na osnovi nočne koncentracije radona v spalnici H1 poleti za faktor 4,7 nižja od zimske, v spalnici H2 pa za faktor 5,1.
Found in: osebi
Keywords: Radon, kontinuirne meritve, bivalno okolje, prezračevanje, efektivna doza, tektonski prelom
Published: 15.04.2019; Views: 1015; Downloads: 68
.pdf Fulltext (3,52 MB)

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