About phase transitions in Bose gases at constant density and constant pressure

The phase transitions in Bose gases at constant volume and constant pressure are considered. New results for the chemical potential, the effective Landau-Ginzburg free energy and the equation of state of the Bose condensate in ideal Bose gases with a general form of the energy spectrum are presented. Unresolved problems are discussed.Comment: 9 pages, no figs. AIP Proc. of Leiden Workshop (2004) on Realistic Models of Astrophysical Matte

Faktorer som påverkar jordbruksskador från klövviltsbete : en experimentell studie med uthägnader i havre- och vallfält

Ungulates foraging on and damaging agricultural crops are a common phenomenon worldwide, which create conflicts between stakeholders with different economic interests. Further, the spatiotemporal distribution of food and the quality of food is often referred to as the “foodscape”. The purpose with this study was to gain knowledge about which factors determine the level of damage in crops created by foraging ungulates and investigate if drones can be used to estimate crop damage in a more efficient way. To estimate proportion biomass loss in both grass- and oat fields, I used exclosures that prevented ungulate foraging and compared the crop weight inside these exclosures with adjacent control plots that allowed foraging. Within each field, three exclosures were established, two near field edges and one in the center. Aiming to explain the variation in biomass loss, I used several different explanatory variables and conducted a linear mixed model with a backwards elimination approach, to determine the factors with the greatest impact. I also monitored all grass fields with a drone that captured multispectral images, which were used to create NDVI-maps over the fields. Further, I used the NDVI-maps and a linear mixed model to investigate if NDVI was correlated with biomass weight in grass fields. I found that proportion of arable land surrounding a field had the greatest impact on the variation in biomass loss. Proportion of arable land had a negative correlation with biomass loss for both oat- and grass fields. For grass fields, there were also a positive correlation between biomass weight in non-foraged plots and biomass loss. Furthermore, NDVI showed a strong positive correlation with biomass weight in grass fields, which suggests that drones could be used to streamline estimates of biomass loss in grass fields. In conclusion, the foodscape is an important factor determining agricultural damage by foraging ungulates. Therefore, instead of decreasing ungulate populations, more focus needs to be placed on improving the foodscape for ungulates

HISTORICAL PERIODIZATION OF ADVERTISING – PROBLEMS AND INTENTIONS

The article focuses on certain discrepancies in the historical periodization of advertising artefacts and practices, found out when studying the development of advertising in literary sources intended for educational purposes, as well as on the problematic semantics of some of the terms used

Spectroscopic investigation of palladium catalysts during wet methane oxidation

Abatement of the strong greenhouse gas methane in vehicle applications by use of catalytic end-of-pipe technologies is challenging due to the prevailing reaction conditions with low temperatures and high water content. In this thesis, the mechanisms behind low-temperature water inhibition of lean methane oxidation over palladium-based catalysts have been studied using an integrated experimental approach including wet-chemical preparation of model catalysts with systematic variation of key performance parameters, transient measurements of reaction kinetics in chemical flow reactor, and operando infrared and X-ray absorption spectroscopic characterisation. For Pd/γ-Al2O3 catalysts, well developed PdO particles is the most active phase and the apparent activation energy for methane oxidation is significantly higher in presence of water.\ua0 It increases with decreasing palladium particle size in the presence of water as opposed to dry conditions where it decreases slightly. Linear and bridge-bonded hydroxyl surface species on alumina evolve during dry methane oxidation by spill-over of hydrogen species to the Pd/γ-Al2O3 rim, which correlates with a declining catalytic activity.\ua0 Addition of water causes severe hydroxylation of the Pd/γ-Al2O3 catalysts that significantly hamper the methane turnover frequency.\ua0 On the contrary, for Pd/ZSM-5 catalysts, hydroxyl formation on the Pd-ZSM-5 rim can not be detected in dry conditions, and is minor upon water addition. A high but not too high palladium dispersion, with palladium particle size not smaller than about 2 nm, is suggested for Pd/γ-Al2O3 catalysts as to balance water tolerance against palladium utilization. Lastly, ZSM-5 supported Pd-based catalysts show outstanding long-term performance for methane oxidation in the presence of water vapor compared to catalysts supported by γ-Al2O3. This finding stimulates the use of hydrophobic support materials given that palladium particles are sufficiently stabilized

An Analysis of a Recursive and an Iterative Algorithm for Generating Permutations Modified for Travelling Salesman Problem

This paper presents the results of a comparative analysis between a recursive and an iterative algorithm when generating permutation. A number of studies discussing the problem and some methods dealing with its solution are analyzed. Recursion and iteration are approaches used in computer programs to implement different algorithms. An iterative approach is the repeated execution of the same source code until a certain end condition is met. On the other hand, a recursive approach uses a recursive function that repeatedly calls itself. This function contains a source code that must be executed repeatedly. Both algorithms presented in this paper can be used to generate permutations of an n element set. The algorithms are modified so that they can be used to solve the Travelling Salesman Problem (TSP) with a small number of vertices. Several publications that discuss the TSP and some approaches to its solution are also presented. The methodology and the conditions for conducting the experiments are described in details. The obtained results have been analyzed; they show that for the same conditions the iterative algorithm works from of 8 to 16 times faster than the recursive algorithm in all the tested input data. Several approaches to optimize the two algorithms in terms of the number of permutations tested when searching a minimal Hamiltonian cycle are presented