1. Performance analysis of high-spectral-resolution lidar with/without laser seeding technique for measuring aerosol optical propertiesFengjia Gao, Fei Gao, Gaipan Li, Fan Yang, Li Wang, Song Yuehui, Dengxin Hua, Samo Stanič, 2024, izvirni znanstveni članek Opis: 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.
Ključne besede: aerosol optical properties, high-spectral-resolution lidar, single-longitudinal-mode, multi-longitudinal-mode, spectral discrimination ratio
Objavljeno v RUNG: 28.02.2024; Ogledov: 328; Prenosov: 2
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2. Recent measurement of the Telescope Array energy spectrum and observation of the shoulder feature in the Northern HemisphereD. Ivanov, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: 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.
Ključne besede: Telescope Array, High Resolution Fly's Eye, HiRes, indirect detection, hybrid detection, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, GZK
Objavljeno v RUNG: 02.10.2023; Ogledov: 504; Prenosov: 6
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3. Performance of the Cherenkov Telescope Array in the presence of cloudsMario Pecimotika, Saptashwa Bhattacharyya, Barbara MARČUN, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, objavljeni znanstveni prispevek na konferenci Opis: 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.
Ključne besede: Cherenkov Telescope Array, very-high energy gamma rays, MODerate resolution atmospheric TRANsmission code, MAGIC Analysis and Reconstruction Software
Objavljeno v RUNG: 18.09.2023; Ogledov: 617; Prenosov: 4
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4. Investigation of the effective transmittance of Mach-Zehnder interferometer in the multi-longitudinal-mode high-spectral-resolution lidarFei Gao, Fengjia Gao, Xiao Yang, Gaipan Li, Li Wang, Meng Wang, Dengxin Hua, Griša Močnik, Samo Stanič, 2022, izvirni znanstveni članek Opis: 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.
Ključne besede: effective transmittance, Mach-Zehnder interferometer, Multi-logitudinal-mode laser, High-spectral-resolution lidar
Objavljeno v RUNG: 20.09.2022; Ogledov: 1436; Prenosov: 0
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5. 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 SCREENINGAlice Avian, 2020, doktorska disertacija Opis: 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.
Ključne besede: Human Papillomavirus, HPV test, cervical cancer screening, prevention, diagnostic test, High resolution melting, HRM, genotyping, PCR, Self-sampling, clinical validation.
Objavljeno v RUNG: 17.06.2020; Ogledov: 3486; Prenosov: 106
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6. Uranium bearing dissolved organic matter in the porewaters of uranium contaminated lake sedimentsBreda Novotnik, Wei Chen, R. Douglas Evans, 2018, izvirni znanstveni članek Opis: Uranium (U) mobility in the environment strongly depends on its oxidation state and the presence of complexing
agents such as inorganic carbon, phosphates, and dissolved organic matter (DOM). Despite the importance of
DOM in U mobility, the exact mechanism is still poorly understood. Therefore, the aim of our investigation was
to characterise sediment porewater DOM in two lakes in Ontario, Canada (Bow and Bentley Lakes) that were
historically contaminated with U and propose possible composition of UO2-bearing DOM. Depth profiles of U
concentrations in porewaters and total sediment digests reveal U levels of up to 1.3 mg L−1 in porewater and up
to 0.8 mg−1 g in sediment. Depth profiles of U did not correlate with Fe, Mn, SO4
2−, or Eh profiles. Therefore,
porewater DOM was analysed and taken into consideration as the primary source of U mobility. Porewater DOM
in each sediment section (1 cm sections, 20 cm core length) was analysed by high-resolution electrospray ionisation
mass spectrometry. PCA analyses of porewater DOM mass spectra showed grouping and clear separation
of DOM in sediment sections with elevated U concentrations in comparison to sections with background U
concentrations. Several criteria were set to characterise UO2-bearing DOM and more than 70 different molecules
were found. The vast majority of these UO2-DOM compounds fell in the category of carboxyl-containing aliphatic
molecules (H/C between 0.85 and 1.2 and O/C≤0.4) and had a mean value of m/z about 720.
Ključne besede: Uranium
Lake sediments
Porewater
Disolved organic matter
High resolution mass spectrometry
Objavljeno v RUNG: 09.10.2019; Ogledov: 3185; Prenosov: 0
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