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Limit cycles with chattering in relay feedback systems

Relay feedback has a large variety of applications in control engineering. Several interesting phenomena occur in simple relay systems. In the paper, scalar linear systems with relay feedback are analyzed. It is shown that a limit cycle where part of the limit cycle consists of fast relay switchings can occur. This chattering is analyzed in detail and conditions for approximating it by a sliding m

GaAs : Mn nanowires grown by molecular beam epitaxy of (Ga,Mn)As at MnAs segregation conditions

GaAs:Mn nanowires were obtained on GaAs(001) and GaAs(111)B substrates by molecular beam epitaxial growth of (Ga,Mn)As at conditions leading to MnAs phase separation. Their density is proportional to the density of catalyzing MnAs nanoislands, which can be controlled by the Mn flux and/or the substrate temperature. After deposition corresponding to a 200 nm thick (Ga,Mn)As layer the nanowires are

Photocurrent spectroscopy on self-assembled InAs quantum dots embedded in InP

In this work, we report on an overview of recent results from Fourier transform photocurrent (FTPC) measurements in the infrared spectral region on ensembles of self-assembled InAs quantum dots embedded in a matrix of InP. In interband PC, clear signals related to the dots are observed. Comparing the PC- and PL spectra, we observe that the fundamental transition is absent in the PC spectra, which

Desmopressin in the treatment of nocturia: A double-blind, placebo-controlled study

Objectives: To investigate efficacy, safety, and impact on quality of sleep of desmopressin in the treatment of nocturia. Methods: Adults aged >= 18 yr with nocturia (>= 2 voids/night) received desmopressin tablets (0.1, 0.2, or 0.4 mg) during a 3-wk dose-titration period. Patients should show sufficient response during the dose-titration period (>= 20% reduction in nocturnal diuresis) and a retur

The REAL process - a process for recycling sludge from water works

In order to produce drinking water, coagulants - such as aluminium salts - are widely used for precipitation and separation of impurities from raw water. The residual from the process is sludge, which presents a disposal problem. The REAL process is a method for recycling the aluminium from the sludge. In a first step, the aluminium hydroxide is dissolved in sulphuric acid. In a second step, an ul

Alla lika - alla olika: skolsituationen för elever med båda föräldrarna födda utomlands

Popular Abstract in Swedish I denna avhandling studeras skolsituationen för elever med båda föräldrarna födda utomlands. Samband mellan elevernas bakgrund, övriga faktorer som i tidigare forskning visat sig betydelsefulla och skolresultat identifieras och analyseras. Studien utgår från de data som insamlades inom ramen för "Det nationella programmet för utvärdering", som genomfördes 1992. UtvärderThe overall purpose of this study was to provide knowledge about the school situation of pupils in Sweden whose parents were both born abroad. The connections between the pupils’ background, other factors shown to be significant in earlier studies, and school results have been identified and analysed. The study was based on the data compiled as part of the National Programme of Evaluation, which w

Critical involvement of cAMP/DARPP-32 and extracellular signal-regulated protein kinase signaling in L-DOPA-induced dyskinesia

The molecular basis of L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID), one of the major hindrances in the current therapy for Parkinson's disease, is still unclear. We show that attenuation of cAMP signaling in the medium spiny neurons of the striatum, achieved by genetic inactivation of the dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32), reduces LID. We also show

PCB in soils and estimated soil-air exchange fluxes of selected PCB congeners in the south of Sweden

PCB concentrations were studied in different soils to determine the spatial variation over a region of approximately 11000 km(2). PCB congener pattern was used to illustrate the spatial differences, as shown by principal component analysis (PCA). The relationship to different soil parameters was studied. PCB concentrations in soil showed a large variation between sampling-areas with median concent

Starch hydrolysing Bacillus halodurans isolates from a Kenyan soda lake

Fourteen obligate alkaliphilic and halotolerant bacterial isolates, exhibiting extracellular amylase activity at 55degreesC and pH 10, were isolated from hot springs around Lake Bogoria, Kenya. From 16S rDNA sequence analysis, nine isolates shared 100% identity with Bacillus halodurans strain DSM 497(T), while the rest shared 99% identity with alkaliphilic Bacillus species A-59. PCR of the interge

Growth and characterization of defect free GaAs nanowires

Most III-V compound semiconductor nanowires seeded by metal particles grow preferentially in a (over bar 1 over bar 1 over bar 1)B direction (B wires) and most commonly with many stacking faults perpendicular to the growth direction. If growth proceeds in an alternate direction, defect-free growth has been observed. We present experimental results for the growth of GaAs nanowires in a previously u

The water dimer in a too tight matrix cage

When an argon matrix containing hydrogen peroxide dimer is irradiated with 266 nm radiation from a YAG laser, water forms. Some of it is formed as monomer but the main part is formed as dimer. The photogenerated water dimer is formed together with an oxygen molecule in the cage of the parent hydrogen peroxide dimer and the dimer bands are shifted from their normal positions indicating that the cag