Minimum variance control of difference equations systems with time-varying stochastic parameters are studied. The optimal control law is derived under the assumption that all previous, but not the current parameter values are known. This is used to give performance limits for dual control. In particular, it is shown that too much parameter uncertainty may cause the system to be unstable in the sen

The flux of an ion in an ionic solution is due to a concentration gradient and an electrical potential gradient. The latter is a result of differences in the diffusion constants of the diffusing ions. Even though it is possible to express the electrical potential gradient in terms of concentrations and concentration gradients, it results in a complicated system to solve if more than two species di

Pigmentation in the freshwater isopod Asellus aquaticus (Crustacea) differed between habitats in two Swedish lakes. In both lakes, isopods had lighter pigmentation in stands of submerged vegetation, consisting of stoneworts (Chara spp.), than in nearby stands of reed (Phragmites australis). Experimental crossings of light and dark isopods in a common environment showed that pigmentation had a gene

The appropriate secretion of insulin from pancreatic beta-cells is critically important to the maintenance of energy homeostasis. The beta-cells must sense and respond suitably to postprandial increases of blood glucose, and perturbation of glucose-sensing in these cells can lead to hypoglycaemia or hyperglycaemias and ultimately diabetes. Here, we review beta-cell glucose-sensing with a particula

Background: The human genome comprises numerous human endogenous retroviruses ( HERVs) that formed millions of years ago in ancestral species. A number of loci of the HERV-K(HML-2) family are evolutionarily much younger. A recent study suggested an infectious HERV-K(HML-2) variant in humans and other primates. Isolating such a varian t from human individuals would be a significant finding for huma

The diastereoselectivity of the carbonyl reduction of bicyclo[2.2.2]octane-2,6-dione, catalysed by the purified yeast cytosolic short-chain dehydrogenase Ymr226cp, was shown to be substrate concentration dependent. The changing selectivity was attributed to two distinct binding configurations of the substrate in the active site, each yielding a distinct hydroxy ketone diastereomer. By applying ind

We study two-terminal hole spin transport in a p-type, light-hole-heavy-hole coupled, quantum-well system under the influence of Rashba spin-orbit interaction. An expression for the spin polarization of the outgoing hole flux is derived. It is shown that the in-plane spin polarization vanishes identically whenever the outgoing lead supports only heavy-hole channels. This result is independent of t

A variational formulation is used to calculate the sound absorption in order to incorporate the interaction between several absorbing patches of arbitrary shape. In particular, this formulation is applied to small periodic patches. The absorption characteristics are governed by the radiation impedance, Z(r), which is a function of the absorber's geometry and the incidence angle, together with the

In this study, we introduce the architecture and style of sedimentation of two outwash fans in front of the Myrdalsjokull ice cap, central south Iceland, that broaden different types of ice-marginal sedimentation. At Kotlujokull, a southeastern outlet of the ice cap, fan formation was monitored from the late 1970s to 2002; thus, the style of sedimentation is well understood and the relationship to

Emerging knowledge of cartilage metabolism and structure has stimulated efforts to develop new cartilage-monitoring techniques in health and disease. This article gives an overview of cartilage matrix structure, cartilage metabolism, and significant exogenous factor's to show how such knowledge can guide the development of new means to monitor cartilage. Delayed contrast enhanced MRI of cartilage

Histological slides from the lungs of 89 dead asbestos cement workers have been examined with respect to ferruginous bodies and fibrosis. The results have been compared with individually matched controls with no known exposure to asbestos, and related to asbestos exposure, expressed as duration of exposure and cumulative asbestos dose, and smoking habits. The asbestos cement workers studied had be

A systematic study of the population probabilities of nanosecond and microsecond isomers produced following the projectile fragmentation of U-238 at 750 MeV/nucleon has been undertaken at the SIS/FRS facility at GSI. Approximately 15 isomeric states in neutron-deficient nuclei around A similar to 190 were identified and the corresponding. isomeric ratios determined. The results are compared with a

Single-particle kinetic energy spectra and two-particle small angle correlations of protons (p), deuterons (d) and tritons (t) have been measured simultaneously in 61 A MeV Ar-36 + Al-27, Sn-112 and Sn-124 collisions. Characteristics of the emission sources have been derived from a "source identification plot" (beta(source)-E-CM plot), constructed from the single-particle invariant spectra, and co

A new deglaciation chronology for the ice-free parts of Greenland, the continental shelf and eastern Ellesmere Island (Canada) is proposed. The chronology is based on a new compilation of all published radiocarbon dates from Greenland, and includes crucial new material from southern, northeastern and northwestern Greenland. Although each date provides only a minimum age for the local deglaciation,