Nonapproximability Results for Partially Observable Markov Decision Processes

We show that for several variations of partially observable Markov decision processes, polynomial-time algorithms for finding control policies are unlikely to or simply don't have guarantees of finding policies within a constant factor or a constant summand of optimal. Here "unlikely" means "unless some complexity classes collapse," where the collapses considered are P=NP, P=PSPACE, or P=EXP. Until or unless these collapses are shown to hold, any control-policy designer must choose between such performance guarantees and efficient computation

Fractionation of the Lipoproteins of the Fat Globule Membrane from Cream

Summary The membrane material obtained by freezing washed cream has been fractionated from suspensions in 2% sodium desoxycholate into five sedimentable fractions representing 75% of the total material and one soluble fraction (25%). These fractions were clearly differentiated by their appearance and sedimentation behavior. Fractions A and D contained most of the xanthine oxidase activity and were about 32% lipid. Fraction B contained most of the alkaline phosphatase activity and was about 65% lipid. The other fractions were over 70% lipid. In Fractions A, B, and D, the lipid was 15% phospholipid; in Fractions C and E, it was 5–6% phospholipid; and in the supernatant, it was 50% phospholipid

Finite Memory Policies for Partially Observable Markov Decision Proesses

This dissertation makes contributions to areas of research on planning with POMDPs: complexity theoretic results and heuristic techniques. The most important contributions are probably the complexity of approximating the optimal history-dependent finite-horizon policy for a POMDP, and the idea of heuristic search over the space of FFTs

Om sambandet mellan logopedens röstkvalitet, språkförståelse och kognitiv förmåga hos barnet

Övergripande syfte med föreliggande studie var att undersöka hur en talares röstkvalitet påverkar språkförståelsen hos barn i åldern åtta år samt vilken roll barnets kognitiva förmågor spelar för språkförståelsen vid varierande röstvillkor. Det saknas idag svenska studier om i vilken utsträckning en talares röstkvalitet påverkar barns förståelse och lärande. Inte heller har man tidigare studerat hur arbetsminneskapacitet och exekutiva funktioner inverkar på språkförståelsen hos barnet vid olika röstvillkor hos talaren. Kunskap inom detta område är av stor vikt för såväl logopediskt arbete som för insatser i skolvärlden. Totalt 85 barn i årskurs 2 deltog i studien. Barnen medverkade i tre deltest; ett test avsett att mäta arbetsminneskapacitet, ett test avsett att mäta exekutiva funktioner samt ett digitaliserat språkförståelsetest, där testmeningarna var inspelade med två olika röstkvaliteter. Barnen delades in i två grupper, där den ena gruppen av barn fick lyssna på en typisk röst och den andra gruppen av barn fick lyssna på en dysfonisk röst. Resultatet på språkförståelsetestet visade ingen signifikant skillnad mellan de olika grupperna. Däremot noterades ett ökat antal självkorrigeringar i den grupp som fick lyssna på dysfonisk röstkvalitet. Även kognitiva funktioner visade sig ha större betydelse för språkförståelsen i den grupp som presenterades för en talare med dysfonisk röstkvalitet

LABOUR MARKET TRENDS AND OCCUPATIONAL INTERESTS OF YOUTH IN LATVIA

The 21st century has witnessed significant changes in the labour market and production structure. It is important to forecast these changes on an on-going basis in order to ensure a balance between the demand in the labour market for workers with adequate qualifications and their supply. The aim of the paper is to study the labour market forecasts for Latvia and on their basis to find out whether the present structure of the education system will meet the labour market demands for professionals with appropriate qualifications, to detect problems and to propose possible solutions. To achieve the purpose of this study, the paper describes the present situation in the labour market; the development trends of the labour market in Latvia were analysed up to 2030 and broken down by sectors of national economy and occupational groups, as well as by changes in educational levels and academic disciplines. The finding of the study is that the present structure of higher education does not match the forecasts for the development of the labour market, concerning the demand for specialists with the highest qualifications in particular. The occupational interests of the young people who were interviewed are not harmonised with the demand in the economy. This proves that, in order to coordinate further directions for action between the employment, education and structural policy makers, social partners and scientists, it is important to take into consideration labour market forecasts and their analysis so that a balanced development would be facilitated in accordance with the demands of today\u27s labour market

Maintenance of respiratory control in mitochondria after rate zonal centrifugation

The respiratory control of rat liver mitochondria is lost when they are subjected to rate zonal centrifugation in a sucrose gradient (8.0% to 46.6%, w/w) at values for ω 2 t necessary for resolution. High sucrose concentration and high ω 2 t are both responsible. Respiratory control can be maintained in iso-osmotic Ficoll + 8.3% sucrose media, and after zonal centrifugation in such media at values of ω 2 t sufficient for resolution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44800/1/10863_2005_Article_BF01539061.pd

Notice nécrologique sur le professeur Umberto Ricci

Lusena Alberto. Notice nécrologique sur le professeur Umberto Ricci. In: Bulletin de l'Institut d'Egypte, tome 28, 1945. pp. 215-252