<p> An expression is obtained for the energy per particle in neutron star matter. The energy per particle is expressed as a function of, y, the ratio of protons to the total number of nucleons in the system. Minimizing the energy with respect to y gives the optimum proton ratio at a given density. Using an effective nuclear force, the results were extrapolated to a density of p = 6pNM. The proton ratio is rather sensitive to the force used, but all forces used indicated a peak in the proton concentration at p (approximately equal to) 2pNM. The expression for the energy as a function of y was also used to interpolate the energy per particle between the nuclear matter and neutron . gas limits. The form of this interpolation is important in determining the stability of neutron-rich nuclei. </p> / Thesis / Master of Science (MSc)

Human exposure to per- and poly-fluoroalkyl substances (PFAS) occurs mainly through two pathways, inhalation and ingestion. Dietary exposure to persistent organic pollutants (POPs), including PFAS, is driven mainly by the consumption of foods of marine or terrestrial animal origin. Therefore, the intake of fish from waters in populated or polluted areas may be a source of human exposure to PFAS. The overall aim of the study was to estimate human exposure to PFAS through the consumption of fish caught in Swedish waters. Analyses of extractable organofluorine (EOF) were performed to serve as an important metric alongside target analysis to better understand the total amount of PFAS in the human sera and fish samples. The serum samples represent individuals who have lived at some point about 5 km from the glass industry in Nybro and Emmaboda. For this study with the Glasbruket study population, the highest concentrations were found for PFOS followed by PFOA, PFNA and PFHxS (medians of 7.9, 1.9, 1.4 and 0.8 ng/mL). Also, the difference in this population between men/women and high/low fish consumers were also addressed. It was stated that there was a statistically significant difference in average Σ17 PFAS concentration between the male and female groups (p &lt; 0.05, two-tailed test). However, the differences between the low and high consumer groups were not statistically significant even though the PFAS levels were higher in the high consumer group. The organofluorine mass balance analysis revealed that 80.1% (ranged from 68.3−93.7%) of the EOF in female samples could not be explained, whereas 57.3% (ranged from 0−99.4%) for the male group was of unidentified origin. Two methods were evaluated for PFAS and EOF analysis of fish muscle, namely, acetonitrile extraction and ion-pair extraction. The selected method, the ion-pair extraction, was performed on fish muscle samples. The fish species included perch (Perca fluviatilis), northern pike (Esox Lucius) and zander (Sander lucioperca) that were collected from seven different lakes in the vicinity of Nyro and Emmaboda. The sum of targeted PFAS (∑14PFAS) across all fish samples analysed ranged from 0.9 to 6.2 ng/g. Mostly, perfluoroalkyl carboxylic acids (PFCAs), precursors to PFCAs and novel PFAS were found in the fish samples. A large part of the EOF content cannot be identified with the targeted PFAS compounds. The average identified EOF fraction for all fish was 2.3% (ranging from 0.8 to 7.2%). For this study, 10 PFAS were found in both sera and fish samples. Therefore, freshwater fish consumption can be identified as one of the contributors to the PFAS concentrations in the Glasbruket population. The fish samples contained precursor compounds as well, that were not found in human serum. These precursor compounds can contribute to the concentrations of PFAAs in serum through biotransformation in the human body to perfluoroalkyl acids (PFAAs). Due to the widespread use of PFAS and their persistence in the environment, it is difficult to determine the relationship between the levels found in serum and fish. The Glasbruket population could be exposed to other sources besides fish.

Per- and polyfluoroalkyl substances (PFAS) encompass a large group of manufactured compounds that have been used in various production processes such as food packaging, commercial products, workplaces, homes, water supplies, and food. PFAS are persistent, resistant to degradation, and can bioaccumulate. Although an exposure limit that predicts adverse health effects has yet to be determined, the Center for Disease Control and Prevention’s 2015-16 health survey found average blood levels of 4.72 ng/ml for PFOS and 1.56 ng/ml for PFOA. The objective of this research was to evaluate the use of laminar flow tandem mass spectrometry following solid phase extraction (SPE) using weak anion exchange (WAX) properties on the detection and quantitation of PFAS compounds. Seven-point calibration standards applied to this research were prepared using certified reference materials (Wellington Laboratories, Ontario, CA), and calibrators were run without sample extraction. The concentrations varied slightly based on the PFAS analyte of interest. All samples and quality controls were prepared by spiking certified reference material (Wellington Laboratories) into pooled human serum (BioIVT, Westbury, NY, USA). A laminar flow QSight®220 ultra-high pressure liquid chromatography-tandem mass spectrometer (LC-MS/MS, PerkinElmer, Waltham, MA, USA) was equipped with a Selectra C18 100 x 2.1mm x 3μm (UCT, Bristol, PA, USA) column with a Brownlee C18 delay column (PerkinElmer) and followed the LC-MS/MS parameters developed for the method. Extraction was accomplished using a WAX SPE column (UCT, ECWAX053) by first conditioning the columns with 1 mL of methanol (Fisher Scientific, Fair Lawn, NJ, USA) followed by 1 mL of 100 mM pH 7 phosphate buffer (Acros Organics, Geel, Belgium, EU). Samples were loaded onto the column at a rate of 1-2 mL/min. The SPE cartridges were washed with 1 mL of 100 mM pH 7 phosphate buffer and 1 mL of millipore water (Millipore Milli- Q Ultrapure Type 1 water system, Millipore Sigma, Burlington, MA, USA), then dried under full flow for 5 minutes. Elution was carried out with 2.5mL of a 98:2 methanol: OptimaTM grade ammonium hydroxide (Fisher Scientific) solution. The eluted samples were then evaporated to dryness using a MULTIVAP® Nitrogen Evaporator (Organomation,Berlin,MA,USA) at 55°C and 5psi. All samples were reconstituted in 100 μL of a 96:4 methanol:water solution. The parameters assessed followed Academy Standards Board Standard 036: Standard Practices for Method Validation in Forensic Toxicology, including matrix interferences, limit of detection (LOD), limit of quantitation (LOQ), a recovery study, and a calibration model. The results of the study were gathered from the following eleven analytes: PFBA, PFBS, PFHxA, PFHpA, PFHxS, PFOA, PFOS, PFNA, PFDA, PFUnA, and PFDoA. Depending on the analyte, a lower LOQ was established at 0.16 – 1.75ng/mL and an upper LOQ at 43.75 – 51.41 ng/mL. Based on the established linear calibration model an LOD in the range of 0.11 - 0.51 ng/mL was achieved. All eleven PFAS analytes showed an acceptable bias of ±20%. All analytes showed a between-run precision (%CV) in an acceptable range of ±20%. No matrix interferences were detected. The average recovery for SPE ranges from 77.64- 104.73% with recovery of 77.64% for PFBS, 83.89% for PFBA, and 95.64-104.73% for PFHxA, PFHpA, PFHxS, PFOA, PFOS, PFNA, PFDA, PFUnA, and PFDoA. Utilizing the UCT WAX SPE column, good recovery for the PFAS compounds was demonstrated. Further, the extraction technique was efficient for high throughput analysis with the extraction time comparable to other traditional SPE methods. The total analytical run time of 11 minutes using the QSight®220 coupled with the UCT Selectra C18 100 x 2.1mm x 3μm column allowed for adequate re-equilibration and system washes to prevent carryover and contamination of these persistent pollutants with excellent chromatography. Having the ability to efficiently and accurately quantify PFAS compounds in biological matrices will allow for better understanding of prevalence, bioaccumulation in biological matrices, and will aid in understanding how these concentrations relate to various health outcomes.

Thermally-driven slope winds are mesoscale atmospheric circulations, known as breezes, that take place because of the heating (cooling) of the air layer close to the ground during daytime (nighttime). Mostly known to occur on days with weak synoptic forcing and under clear sky conditions, the wind blows up valleys and slopes during the daytime, and in the opposite direction during nighttime. A better comprehension of slope winds can improve the understanding of the soil-atmosphere turbulent exchange processes and of the energy budget over complex terrain, in addition to the evaluation of the along-slope transport of dangerous species (pollutants, pesticides), as well as water vapor (relevant for the development of convection). This research project aims to improve the knowledge of thermally-driven slope winds, with particular attention to the differences between the diurnal and nocturnal regimes. This is done through a multiple-way approach. Field data analysis, analytical solutions with realistic forcing, and numerical models are all employed to fulfill the objective. At first, data from two stations located on slopes were analyzed. Measurements were taken in the surroundings of the Alpine city of Innsbruck, as part of the i-Box field campaign, covering a period of 7 years (2013 to 2020). Observation indicates a marked seasonality of the phenomena, with warm season months being more prone to the occurrence of slope winds. Moreover, the results highlighted the key role played by the local topographical characteristics in the development of pure slope wind days, with both slope angle and orientation playing a major role in the interplay between valley and slope winds. Previous results suggested the development of an improved analytical model which uses the available net radiation at the surface as the forcing for slope circulations, in the form of a truncated Fourier series expansion. The net radiation model accounts for both the seasonality (day of the year) and the local topographic characteristics (latitude, slope angle, orientation, elevation). Therefore, differences in the properties of slope winds occurring in different seasons and on slopes with different slope angles and orientations are highlighted and studied. The last chapter of the thesis investigates the structure of the eddy viscosity and diffusivity employing numerical models. These parameters govern the mass, momentum, and heat turbulent exchanges from slope winds. A simple one-dimensional model was developed to test different turbulence closures. In particular, the attention focused on the so-called K-l closure, meaning that the eddy viscosity and diffusivity parameters are bounded to the turbulence length scale l, representing the distance a turbulent eddy can travel “carrying” heat, momentum, and mass. In the current work, different parameterizations of the turbulence length scale l are tested and compared. Results show how simple K-l closures are compared with other non-constant K profiles proposed in the literature for the case of katabatic winds. Nevertheless, such simple parameterizations for the turbulence length scale l still fail to properly discriminate between the daytime and nighttime regimes of slope winds.

In the present work, micro-tubular solid oxide fuel cells μt-SOFCs) constituted by NiO/YSZ anode with an embedded current collector, YSZ as electrolyte, YSZ/LSM as functional cathode layer and pure LSM as cathode current collector layer were fabricated by dip-coating technique. The fuel cell was designed according to the anode-supported configuration with a metallic coil introduced within the anode during the cell fabrication. The production of the devices through wet colloidal process required the optimization of suspensions employed for the dip-coating. Then, investigation on rheological properties for the anode and electrolyte water-base slurries was carried out with particular emphasis to the solid loading and the concentration of slurry additives as well as temperature. In addition, thermal analyses elucidated the response of anode, electrolyte and cathode layers during drying, binder burn-out and sintering processes. The thermal behaviour of pyrolisable materials and oxidation of the metal components used as current collector was performed using conditions identical to cell fabrication like temperatures as high as 1400°C in oxidative atmosphere. After sintering, the complete μt-SOFCs with embedded current collector were produced with outer diameter as low as 1.0 mm and length of 30 mm with an effective active cathode length of 20 mm resulting in an active area of 0.63 cm2. The cell performance was analyzed by V-j plots in the temperature range of 700-800°C where the effect of the cell diameter and current collector characteristics on power density was pointed out. The efficiency of current collector was examined by comparing coils with different configurations (turns per unit length) as well as nature of the metal. The cell performance was demonstrated to be related to the current collector configuration. In particular, as twice the turns per unit length are as double the current density is, thus making the power density 4-fold. An additional improvement of the cell performance was found for the palladium current collector where the power density was increased by a factor more than 4 in comparison with the cell made with nickel collector due to the higher catalytic activity of palladium for electrochemical reactions. On the basis of these findings, a further development of μt-SOFCs with embedded collector was suggested with an alternative design of palladium current collector for which an estimate of power density of micro-tubular cell provided values higher than 0.7 W/cm2 at temperature of 800°C.

Biology is the science of life and living organisms. Empowered by the deployment of several automated experimental frameworks, this discipline has seen a tremendous growth during the last decades. Recently, the focus towards studying biological systems holistically, has lead to biology converging with other disciplines. In particular, computer science is playing an increasingly important role in biology, because of its ability to disentangle complex system level issues. This increasing interplay between computer science and biology has lead to great progress in both fields and to the opening of new important areas for research. In this thesis we present methods and approaches to tackle the problem of knowledge discovery in computational biology from a stochastic perspective. Major bottlenecks in adopting a stochastic representation can be overcome with the use of proper methodologies by integrating statistics and computer science. In particular we focus on parameter inference for stochastic models and efficient model analysis. We show the application of these approaches on real biological case studies aiming at inferring new knowledge even when a priori (and/or experimental) information is limited.

So far, numerous studies have been devoted to investigate the relationship between happiness and income by asking the question whether economic growth has a positive impact on happiness. However, the reversed relationship from happiness to economic output has received much less attention in the literature. This paper attempts to investigate such relationship by using data from the European Value Survey that contains subjective reported well-being (happiness, or life satisfaction) values across 47 European countries from 1981 to 2009. Gender imbalance is used as an instrument for happiness in order to disentangle the causal effect of happiness on income. Based on a derived Solow model, where labor efficiency is assumed to be positively affected by worker happiness, regression analyses suggest that the sense of happiness does have a positive and highly significant impact on GDP per worker. Robustness tests further show that the result also holds for life satisfaction. According to the results, the author recommends governments to use well-being oriented index, along with GDP to measure the overall economy.

The effect of varying the angle of incidence of a Gaussian beam from a He-Ne laser incident upon a large radius optical fiber is theoretically and experimentally investigated. The modes in a weakly-guiding, step index fiber were determined by using an analytical approximation technique to calculate the corresponding eigenvalues. An expression was developed for the fractional power per mode as a function of the angle of incidence for such a fiber. This expression was used to calculate the fractional power per mode for the lowest order 171 modes. This allowed the calculation of the fractional power per order and total power. By comparing these theoretical results to our experiment results, it is shown that the theoretical method is accurate at normal incidence and gives qualitative but not quantitative agreement at larger angles.

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