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1.
Performance analysis of high-spectral-resolution lidar with/without laser seeding technique for measuring aerosol optical properties
Fengjia Gao, Fei Gao, Gaipan Li, Fan Yang, Li Wang, Song Yuehui, Dengxin Hua, Samo Stanič, 2024, original scientific article

Abstract: High-spectral-resolution lidar (HSRL) is a powerful tool for aerosol measurements. With/without laser seeding technique in the transmitted laser, the HSRL can be distinguished as the single-longitudinal-mode (SLM) HSRL or the multi-longitudinal-mode (MLM) HSRL, and the Mach-Zehnder interferometer (MZI) with periodic transmittance function can be used as the spectral discriminator in both the SLM HSRL and MLM HSRL. To in-depth knowledge of the respective advantages of the SLM HSRL and MLM HSRL for measuring aerosol optical properties, the working principle, optimal parameter setting, and detection performance of the SLM HSRL and MLM HSRL are analyzed and discussed in detail, respectively. The working principle of the SLM HSRL and MLM HSRL indicate that the effective transmittance of MZI is the important parameter of data retrieval, the main source of retrieval uncertainties, and the key factor of MZI optical path difference (OPD) settings. To ensure that the MZI can achieve the preferable separation for aerosol Mie scattering signals and molecular Rayleigh scattering signals, the optimal OPDs of MZI are set at 165 mm and 1000 mm in the SLM HSRL and MLM HSRL from the aspects of the effective transmittance of MZI and the spectral discrimination ratio (SDR). Besides, to analyze the influence of frequency difference and divergence angle for the detection performance of HSRL, the effective transmittance of MZI and SDR are simulated and the results show that the MLM HSRL has higher requirements for the environmental parameters and the echo beam collimation than the SLM HSRL. Moreover, the HSRLs with SLM and MLM transmitted lasers are constructed in Xi'an for measuring aerosol optical properties. The preliminary measurement results show that the range square corrected signal (RSCS) of Rayleigh channel is smaller than that of Mie channel in both the SLM HSRL and MLM HSRL, while the difference between RSCS of Rayleigh channel and RSCS of Mie channel in the SLM HSRL is larger than that in the MLM HSRL, and the detection range of the SLM HSRL is lower than that of the MLM HSRL.
Keywords: aerosol optical properties, high-spectral-resolution lidar, single-longitudinal-mode, multi-longitudinal-mode, spectral discrimination ratio
Published in RUNG: 28.02.2024; Views: 68; Downloads: 0
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3.
Recent measurement of the Telescope Array energy spectrum and observation of the shoulder feature in the Northern Hemisphere
D. Ivanov, Jon Paul Lundquist, 2022, published scientific conference contribution

Abstract: The Telescope Array (TA) is a hybrid cosmic ray detector deployed in 2007 in Millard County, Utah, USA, which consists of a surface detector of 507 plastic scintillation counters spanning a 700 km^2 area on the ground that is overlooked by three fluorescence detector stations. The High Resolution Fly's Eye (HiRes) experiment is a predecessor of TA, which consisted of two fluorescence detector stations operating from 1997 until 2006 from Dugway Proving Ground, Utah, USA, and which was the the first cosmic ray experiment with sufficient resolution and exposure to successfully observe the Greisen–Zatsepin–Kuzmin (GZK) suppression at 10^19.75 eV. In this work, we present an updated TA energy spectrum result and a joint fit of independent spectrum measurements by the TA surface detector, TA fluorescence detector, and HiRes fluorescence detector to a broken power law function, which exhibits the ankle, GZK suppression, and the new shoulder feature initially seen by the Pierre Auger Observatory in the Southern Hemisphere. HiRes and TA observe the shoulder feature in the Northern Hemisphere at 10^19.25 eV, with a statistical significance of 5.3 standard deviations.
Keywords: Telescope Array, High Resolution Fly's Eye, HiRes, indirect detection, hybrid detection, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, GZK
Published in RUNG: 02.10.2023; Views: 393; Downloads: 6
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4.
Performance of the Cherenkov Telescope Array in the presence of clouds
Mario Pecimotika, Saptashwa Bhattacharyya, Barbara MARČUN, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, published scientific conference contribution

Abstract: The Cherenkov Telescope Array (CTA) is the future ground-based observatory for gamma-ray astronomy at very high energies. The atmosphere is an integral part of every Cherenkov telescope. Di˙erent atmospheric conditions, such as clouds, can reduce the fraction of Cherenkov photons produced in air showers that reach ground-based telescopes, which may a˙ect the performance. Decreased sensitivity of the telescopes may lead to misconstructed energies and spectra. This study presents the impact of various atmospheric conditions on CTA performance. The atmospheric transmission in a cloudy atmosphere in the wavelength range from 203 nm to 1000 nm was simulated for di˙erent cloud bases and di˙erent optical depths using the MODerate resolution atmospheric TRANsmission (MODTRAN) code. MODTRAN output files were used as inputs for generic Monte Carlo simulations. The analysis was performed using the MAGIC Analysis and Reconstruction Software (MARS) adapted for CTA. As expected, the e˙ects of clouds are most evident at low energies, near the energy threshold. Even in the presence of dense clouds, high-energy gamma rays may still trigger the telescopes if the first interaction occurs lower in the atmosphere, below the cloud base. A method to analyze very high-energy data obtained in the presence of clouds is presented. The systematic uncertainties of the method are evaluated. These studies help to gain more precise knowledge about the CTA response to cloudy conditions and give insights on how to proceed with data obtained in such conditions. This may prove crucial for alert-based observations and time-critical studies of transient phenomena.
Keywords: Cherenkov Telescope Array, very-high energy gamma rays, MODerate resolution atmospheric TRANsmission code, MAGIC Analysis and Reconstruction Software
Published in RUNG: 18.09.2023; Views: 492; Downloads: 4
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Investigation of the effective transmittance of Mach-Zehnder interferometer in the multi-longitudinal-mode high-spectral-resolution lidar
Fei Gao, Fengjia Gao, Xiao Yang, Gaipan Li, Li Wang, Meng Wang, Dengxin Hua, Griša Močnik, Samo Stanič, 2022, original scientific article

Abstract: Effective transmittance is an important parameter of Mach-Zehnder interferometer in the retrieval of aerosol optical properties using the multi-longitudinal-mode high-spectral-resolution lidar, which is a function of the complex degree of coherence. In this paper, we retrieve the parameter of the complex degree of coherence for the multi-longitudinal-mode laser from the theoretical analysis, optical simulation and experimental measurements, which are 0.726, 0.678 and 0.453 using the Mach-Zehnder interferometer with the optimal optical path difference of two times of laser optical cavity length (∼1000 mm) and under the light illumination of the high power Nd:YAG laser with the mode number of 101 and mode interval of 300 MHz under the condition of laser linewidth of 1 cm−1 (30 GHz). The preliminary measurement results of aerosol optical properties using the constructing multi-longitudinal-mode high-spectral-resolution lidar show that the difference of the complex degree of coherence retrieved from the presented methods results in the relative error of 40% in the aerosol backscattering coefficient with thin cloud layer and 90% with the presence of dense aerosol layer.
Keywords: effective transmittance, Mach-Zehnder interferometer, Multi-logitudinal-mode laser, High-spectral-resolution lidar
Published in RUNG: 20.09.2022; Views: 1303; Downloads: 0
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7.
Gender agreement with exclusive disjunction in Slovenian
Franc Marušič, Zheng Shen, 2021, original scientific article

Abstract: This paper addresses two issues: 1. Empirically, we report novel experimental data on agreement with exclusively disjoined subjects in Slovenian; 2. Theoretically, we look into the nature of attested agreement strategies with coordinated NPs. In particular, we investigate how these strategies behave under coordinators with different semantics, i.e. exclusive disjunction and conjunction. Based on the elicitation results, we argue that closest conjunct agreement, resolved agreement, and highest conjunct agreement are all present under exclusive disjunction to different extents, which suggests a uniform set of agreement strategies under disjunction and conjunction despite the semantic difference. Further, we argue against the presence of default agreement under both disjunction and conjunction in Slovenian, and argue for a particular set of gender resolution rules.
Keywords: Slovenian, conjunct agreement, exclisuve disjunction, resolution, default agreement
Published in RUNG: 15.11.2021; Views: 1470; Downloads: 0
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8.
Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory : a case study with a long-range transported biomass burning plume
Katja Džepina, Claudio Mazzoleni, Paulo Fialho, Swarup China, Bo Zhang, R. Chris Owen, D. Helmig, J. Hueber, Sumit Kumar, J. A. Perlinger, 2015, original scientific article

Abstract: Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m above mean sea level on Pico Island of the Azores archipelago in the North Atlantic. The observatory is located ∼ 3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 µg m−3 . On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51 %), followed by sulfate (23 ± 28 %), nitrate (13 ± 10 %), chloride (2 ± 3 %), and elemental carbon (2 ± 2 %). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100–1000. The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled air masses were very aged (average plume age > 12 days). These aged aerosol WSOM compounds had an average O /C ratio of ∼ 0.45, which is relatively low compared to O /C ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were more aged and influenced by marine emissions, as indicated by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for the two samples was corroborated by the changes in ethane, propane, and ozone, morphology of particles, as well as by the FLEXPART retroplume simulations. This paper presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere remote location and provides evidence of low oxygenation after long-range transport. We hypothesize this is a result of the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and fragmentation (e.g., photolysis) of components.
Keywords: organic aerosol, ultrahigh-resolution FT-ICR MS, electron microscopy, remote marine atmosphere, Pico Mountain Observatory
Published in RUNG: 11.04.2021; Views: 2152; Downloads: 0
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9.
Molecular and physical characteristics of aerosol at a remote free troposphere site : implications for atmospheric aging
Simeon K. Schum, Bo Zhang, Katja Džepina, Paulo Fialho, Claudio Mazzoleni, Lynn R. Mazzoleni, 2018, original scientific article

Abstract: Aerosol properties are transformed by atmospheric processes during long-range transport and play a key role in the Earth’s radiative balance. To understand the molecular and physical characteristics of free tropospheric aerosol, we studied samples collected at the Pico Mountain Observatory in the North Atlantic. The observatory is located in the marine free troposphere at 2225m above sea level, on Pico Island in the Azores archipelago. The site is ideal for the study of long-range-transported free tropospheric aerosol with minimal local influence. Three aerosol samples with elevated organic carbon concentrations were selected for detailed analysis. FLEXPART retroplumes indicated that two of the samples were influenced by North American wildfire emissions transported in the free troposphere and one by North American outflow mainly transported within the marine boundary layer. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry was used to determine the detailed molecular composition of the samples. Thousands of molecular formulas were assigned to each of the individual samples. On average ~60% of the molecular formulas contained only carbon, hydrogen, and oxygen atoms (CHO), ~ 30% contained nitrogen (CHNO), and ~ 10% contained sulfur (CHOS). The molecular formula compositions of the two wildfire-influenced aerosol samples transported mainly in the free troposphere had relatively low average O=C ratios (0:48 ± 0:13 and 0:45 ± 0:11) despite the 7–10 days of transport time according to FLEXPART. In contrast, the molecular composition of the North American outflow transported mainly in the boundary layer had a higher average O=C ratio (0:57 ± 0:17) with 3 days of transport time. To better understand the difference between free tropospheric transport and boundary layer transport, the meteorological conditions along the FLEXPART simulated transport pathways were extracted from the Global Forecast System analysis for the model grids. We used the extracted meteorological conditions and the observed molecular chemistry to predict the relative-humidity-dependent glass transition temperatures (Tg) of the aerosol components. Comparisons of the Tg to the ambient temperature indicated that a majority of the organic aerosol components transported in the free troposphere were more viscous and therefore less susceptible to oxidation than the organic aerosol components transported in the boundary layer. Although the number of observations is limited, the results suggest that biomass burning organic aerosol injected into the free troposphere is more persistent than organic aerosol in the boundary layer having broader implications for aerosol aging.
Keywords: secondary organic aerosols, brown carbon, particle dispersion model, ultrahigh-resolution FT-ICR MS, Pico Mountain Observatory
Published in RUNG: 10.04.2021; Views: 2182; Downloads: 0
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10.
DEVELOPMENT OF A NOVEL PCR-BASED ASSAY FOR HIGH-RISK HUMAN PAPILLOMAVIRUS DETECTION AND GENOTYPING IN SELF COLLECTED CERVICOVAGINAL SAMPLES: A NEW POSSIBILITY FOR THE CERVICAL CANCER SCREENING
Alice Avian, 2020, doctoral dissertation

Abstract: Human Papillomavirus (HPV) infection is the causative agent for the invasive cervical cancer and its precancerous lesions, furthermore, there are growing evidences of HPV being a relevant factor in other anogenital cancers as well as head and neck cancers. Most sexually active women become infected with HPV at least once in their lifetime, but less than 10% of women becomes persistently infected, and it is precisely the persistent infection that contributes to the development of cervical cancer. The preventive effect of cervical cancer screening largely depends in the high women participation and coverage; indeed, a large number of cervical cancers diagnoses normally arise among under-screened and unscreened women. Increase in the screening coverage is essential to improve the effectiveness of cervical screening programmes. The main purpose of this PhD project was to solve some of the most relevant problems in the cervical cancer screening programmes, as the increase of cost-effectiveness and the amelioration of the screening coverage. My work was focused on the development and validation of the first Ulisse BioMed S.p.A. product, the HPV Selfy™ test, an innovative PCR-based kit for the direct detection and genotyping of 12 high-risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58 and 59) and 2 possible/probable high-risk (66 and 68), specifically optimized for the analysis of self-collected vaginal specimens. The core of this innovative test is based on high-resolution melting (HRM) analysis, a recently developed technique for fast, high-throughput post-PCR analysis of variance in nucleic acid sequences, that characterizes the amplicons by studying thermal denaturation of double-stranded DNA. Based on this approach and through the design of different HPV type-specific primer pairs and the development of a specific master mix, unique melting peaks in a single fluorescence channel were obtained, allowing the multiple detection and genotyping of 14 HPV types in a single PCR well. Three different clinical studies have been carried out to validate the assay on the vaginal self-collected samples with truly amazing results regarding the assay’s performance, but also for self-sampling acceptability by women. Moreover, data collected in these studies suggest a future possible use of this test for the hard-to-reach women, as an alternative of the conventional clinician-collected sample, in order to increase the cervical cancer screening coverage.
Keywords: Human Papillomavirus, HPV test, cervical cancer screening, prevention, diagnostic test, High resolution melting, HRM, genotyping, PCR, Self-sampling, clinical validation.
Published in RUNG: 17.06.2020; Views: 3258; Downloads: 104
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