A fast algorithm for computing distance spectrum of convolutional codes

New rate-compatible convolutional (RCC) codes with high constraint lengths and a wide range of code rates are presented. These new codes originate from rate 1/4 optimum distance spectrum (ODS) convolutional parent encoders with constraint lengths 7-10. Low rate encoders (rates 115 down to 1/10) are found by a nested search, and high rate encoders (rates above 1/4) are found by rate-compatible puncturing. The new codes form rate-compatible code families more powerful and flexible than those previously presented. It is shown that these codes are almost as good as the existing optimum convolutional codes of the same fates. The effects of varying the design parameters of the rate-compatible punctured convolutional (RCPC) codes, i.e., the parent encoder rate, the puncturing period, and the constraint length, are also examined. The new codes are then applied to a multicode direct-sequence code-division multiple-access (DS-CDMA) system and are shown to provide good performance and rate-matching capabilities. The results, which are evaluated in terms of the efficiency for Gaussian and Rayleigh fading channels, show that the system efficiency increases with decreasing code rat

Metabolomics-based analysis in Daphnia magna after exposure to low environmental concentrations of polystyrene nanoparticles

Larger plastic pieces break down into micro- and eventually nano-sized plastics. This makes nanoplastics ubiquitous in the environment, giving rise to great concern for its effect on biota. Many studies use polystyrene nanoparticles (PS-NPs) as a model for nanoplastics, showing a negative impact on various organisms, but the molecular effects are yet not fully explored. Here we applied 1H nuclear magnetic resonance (NMR) metabolomics to characterize the metabolic changes in Daphnia magna during long-term (37 days) exposure to low concentrations of positively and negatively charged (aminated and carboxylated) PS-NPs. We show that exposure to PS-NPs at concentrations down to 3.2 μg L−1 affected amino acid metabolism and the bacterial metabolite isopropanol in D. magna. These effects were largely independent of particle concentration and surface charge. The results highlight the importance of (1) performing chronic exposures under low concentrations and (2) further investigation of particles with different surface charges

Magnetic and mechanical effects of Mn substitutions in AlFe2B2

The mechanical and magnetic properties of the newly discovered MAB-phase class of materials based upon AlFe2B2 were investigated. The samples were synthesised from stoichiometric amounts of all constituent elements. X-ray diffraction shows that the main phase is orthorhombic with an elongated b-axis, similar to AlFe2B2. The low hardness and visual inspection of the samples after deformation indicate that these compounds are deformed via a delamination process. When substituting iron in AlFe2B2 with manganese, the magnetism in the system goes from being ferro- to antiferromagnetic via a disordered ferrimagnetic phase exhibited by AlFeMnB2. Density functional theory calculations indicate a weakening of the magnetic interactions among the transitions metal ions as iron is substituted by manganese in AlFe2B2. The Mn-Mn exchange interactions in AlMn2 B2 are found to be very small

En rättvis fördelning? - En studie av debatten om det kommunalekonomiska skatteutjämningssystemet

Some rural parts of Sweden are facing problems with providing the citizens with welfare benefits due to a decreasing number of inhabitants as well as an older population. A system of tax equalization aims to create equal conditions of welfare between municipalities and between counties throughout the country by allocating and equalizing income tax and structural costs. The system is highly debated and raises the question of what constitutes a fair distribution of economic resources. The aim of this essay is to identify which ideas of distributive justice that can be found it the public debate regarding the system. This is examined through a descriptive text analysis while using several theories of distributive justice amongst the main theories utilitarianism, egalitarianism, desert theory and libertarianism. The conclusion made is that several ideas of distributive justice are expressed through the debate. Furthermore, while the system enjoys a great deal of support some opponents are arguing for a system financed by the state government

Factors and improvments for success in crop production : a survey conducted in the County of Södermanland

I det här arbetet har det gjorts en övergripande undersökning om vilka framgångsfaktorer och förbättringsåtgärder, som har störst betydelse för lantbrukare i Södermanland. Studien grundar sig på fyra frågeställningar som berör olika åtgärder inom växtodling och ifrågasätter deras betydelse i växtodlingsproduktion. Målet med studien är att presentera förbättringsåtgärder som leder till framgång inom växtodling som går att styrka genom litteraturstudien samt svar från en enkätundersökning. Studien är avgränsad till faktorer som enbart berör högre skörd och geografiskt enbart till Södermanland. Litteraturstudien innehåller fakta om några vanligt förekommande faktorer, som behövs för att ge hög avkastning. De faktorer som beskrivs är organisk gödsel, dränering och kalkning och vad dessa har för effekt i marken och växtodlingen. Till enkätundersökningen valdes 20 lantbrukare ut som över telefon blev tillfrågade om att få delta i undersökningen. Nitton lantbrukare tackade ja och fick enkäten utskickad på mail för att fylla i svar och sedan returnera. Tretton enkätsvar kom in som sammanställts och presenteras i resultatdelen. Diskussionen jämför fakta från litteraturstudien med svaren från lantbrukarna. I diskussionen har följande frågor behandlats: • Är tillförsel av organiska gödselmedel en viktig framgångsfaktor för att nå högre avkastning? • Är markförbättrande åtgärder i form av kalkning viktigt för att kunna skapa bra odlingsförhållanden och bygga upp högre skörd från grunden? • Kan markavvattning ses som en grundläggande faktor för att nå framgång inom växtodling? • Vilka framgångsfaktorer anser lantbrukare i Södermanland vara viktigast? Resultatet från enkätundersökningen i jämförelse med de åtgärder som presenteras i litteraturstudien visar på stor betydelse av struktur- och markförbättrande åtgärder i växtodlingen. Lantbrukare i Södermanland bör tillföra organisk gödsel i större utsträckning för att bibehålla mullhalt och bördighet i jorden. Kalkning bör genomföras regelbundet för att upprätthålla rätt pH-värde. Dränering i form av täckdikning bör läggas för att värna om markstrukturen i de styva lerjordarna. Slutsatsen blir därför att struktur- och markförbättrande förbättringsåtgärder är de absolut viktigaste faktorerna för att nå framgång inom växtodling i Södermanland.In this project, an overall survey has been made focusing on which success factors and improvement measures that are important in Södermanland. The study is based on four questions concerning different crop cultivation measures and questioning their importance in crop production. The aim of the study is to present improvement measures that lead to success in crop production that can be strengthened through the literature study as well as answers from a survey. The study is limited to factors that concern increased yield and geographically only to Södermanland.. The study describes what effect organic fertilizers, drainage and liming have in soil and plant cultivation. For the survey, 20 farmers were selected and asked over the phone to participate in the survey. Nineteen farmers said yes and received the questionnaire on mail to fill in replies and then return. Thirteen questionnaire replies came in as compiled and presented in the result section. The discussion compares the facts from the literature study with the answers from the farmers. In the discussion the following issues have been addressed: • Is the supply of organic fertilizers an important success factor in achieving higher harvest? • Are soil enhancing measures in the form of liming important in order to create good cultivation conditions and improve yields? • Can land drainage be seen as a fundamental factor in achieving success in plant breeding? • What success factors do farmers in Södermanland consider to be most important? The results of the survey as compared to the measures presented in the literature study show great importance for structural and soil enhancement measures in plant cultivation. Farmers in Södermanland should supply organic fertilizers to a greater extent to maintain the organic content and fertility in the soil. Liming should be carried out regularly to maintain the correct pH. Drainage in the form of a subsoil drainage should be added to protect the soil structure of the heavy clay soils. The conclusion therefore is that structural and soil improvement measures are the most important factors for achieving success in plant cultivation in Södermanland