The matrix Riccati equation appears in many optimal control and filtering problems. In this paper the Riccati equation is studied from an algebraic point of view, and the results are applied on optimal control of linear time invariant systems with quadratic loss.

Popular Abstract in Swedish Åderförkalkning i benens artärer ger upphov till "fönstertittarsjuka" och, i svåra fall, kritisk ischemi med vilosmärtor och sår eller kallbrand. I dessa sistnämnda fall är risken för en amputation stor. Kärlkirurgiska metoder med s.k. bypassoperationer användes för att söka rädda benen. För detta ändamål används helst patientens egna vener, men i vissa fall måste man aThe expression of surface adhesion molecules on white blood cells (WBC) and platelets, and the release of tumor necrosis factor-alpha (TNF-a) and interleukin-6 (IL-6) after incubation with expanded-polytetrafluoroethylene (ePTFE)- or woven Dacron grafts was determined. Both graft-materials induced alteration of the WBC adhesion molecule receptor and caused release of TNF-a and IL-6, higher for wov

Abstract not available

Semen quality has been reported to vary markedly between different regions. To properly assess the differences among countries a minimization of the variation among centres in the assessments of sperm quality is essential. We here report on the training and two subsequent follow-up workshops on assessments of sperm concentration and motility. A total of 26 fresh ejaculates were analysed by four pe

The material in Swedish herbaria previously identified as Hieracium sublividum (Dahlst.) Johanss. was revised using both the traditional taxonomical approach and PCA analysis based on 44 morphological characters. Only about half of the specimens did belong to H. sublividum s. stricto (known from the provinces Småland, Öland and Östergötland). Three new species were revealed and are described anew

This paper addresses variations in the wind climate in relation to changes in the impact of wind erosion on agricultural lands with Scania, the southernmost province of Sweden, as an example. The literature concerning wind erosion in the region is reviewed and the conclusions are linked to recent analyses of the regional wind climate. Presently, wind erosion occasionally induces problems in light

The role of islet constitutive nitric oxide synthase (cNOS) in insulin-releasing mechanisms is controversial. By measuring enzyme activities and protein expression of NOS isoforms [i.e., cNOS and inducible NOS (iNOS)] in islets of Langerhans cells in relation to insulin secretion, we show that glucose dose-dependently stimulates islet activities of both cNOS and iNOS, that cNOS-derived nitric oxid

Structural biology has transformed a number of fields of biochemistry and biology. A few examples are the following. The allosteric uptake and release of oxygen from haemoglobin obtained an elegant description from the work of Perutz [ Perutz ( 1970), Nature ( London), 227, 726 - 739; Perutz et al. ( 1998), Annu. Rev. Biophys. Biomol. Struct. 27, 1 - 34]. The structure of tRNA highlighted the fact

High-resolution capacitance measurements were used to explore the effects of the gut hormones GLP-I(7-36) amide [glucagon-like peptide I(7-36) amide] and GIP (glucose-dependent insulinotropic polypeptide) on Ca2+-dependent exocytosis in glucagon-secreting rat pancreatic alpha-cells. Both peptides produced a greater than threefold potentiation of secretion evoked by voltage-clamp depolarizations, a

Aim: To identify early predictors of outcome in infants born at 25 gestational weeks. Material and Methods: Data from a regional perinatal database (time-period 1995-2001, total n = 108 000 births) were used. Apgar scores were available in 92 preterm infants, born at 25 + 0 to 25 + 6 gestational weeks, and analyzed in relation to short-term outcome (180-day survival with, or without, severe brain

Dynorphin B (dyn B) in trigeminal ganglion cells and in perivascular nerve fibers in pial arteries was demonstrated in rat, guinea-pig, and monkey by immunohistochemistry. The pathway from the trigeminal ganglion, which runs via the nasociliary nerve and ethmoidal foramen to the pial arteries, was shown in rat by retrograde tracer technique and nerve section. In the guinea-pig the peptide was demo

This prospective observational data collection study assessed the cost and quality of life related to hip, vertebral and wrist fracture 1 year after the fracture, based on a patient sample consisting of 635 male and female patients surviving a year after fracture. Data regarding resource use and quality of life related to fractures was collected by questionnaires at baseline, 4 months and 12 month

Recently, the structure of protein ions in vacuo has received a lot of interest. Experimentally, such structures can only be characterized by global, low-resolution descriptors like the orientationally-averaged collision cross section (σ) over bar. An alternative descriptor of chain entanglement, the mean overcrossing number (N) over bar, is a very useful tool because it can distinguish sensitivel

Abstract in French Cette étude a été réalisée pour déterminer si les papillomatoses virales du col sont associées à l'utilisation des contraceptifs et aux antécédents de reproduction. Après avoir enregistré les antécédents de contraception et de reproduction de 972 femmes ayant demandé des conseils en matière de contraception, des examens ont été conduits pour dépister toute infection de papillomaThe study was conducted to investigate whether cervical human papillomavirus infections (CHPI) are associated with contraceptive use and reproductive history. The contraceptive and reproductive histories in 972 women seeking contraceptive advice were noted and screening conducted for human papillomavirus infection. The interview included number of pregnancies and childbirths, legal and spontaneous