On the realization of periodic functions

In this article, canonical and spectrally minimal infinite-dimensional state space realizations for periodic functions are considered. It is shown that the periodic functions having ℓ₁ Fourier coefficients are precisely those realizable by a Riesz spectral system (RSS) in which the system operator generates a periodic strongly continuous semigroup and the observation operator is bounded. This realization can easily be converted to a canonical and spectrally minimal form. It is shown how the use of RSS and Cesáro sums of Fourier series allows the construction of a state space realization for a given periodic function merely integrable over its period. Simple finite-dimensional approximations with error bounds are derived for the RSS realization. Regular well-posed linear systems (WPLS) are used to construct a Fuhrmann-type realization for a given periodic function integrable over its period. It is shown that the RSS realizations and WPLS realizations are precisely equally good at coping with the possible ill behavior of a given bounded periodic function integrable over its period, but the WPLS realization is not always spectrally minimal or canonical.     

Bovine muscle glycogen concentration in relation to finishing diet, slaughter and ultimate pH

The aim of this study was to investigate the effects of a high-energy diet provided for a rather short time prior to transportation to slaughter on muscle glycogen concentration on farm, after transportation and after refrigeration of the carcasses. The experiment involved 60 Ayrshire bulls which were fed either a low energy diet of 100% grass silage or a compound feed based diet providing 10.8 and 12.9 MJ of metabolizable energy per kg of dry matter, respectively. Identical setup of 30 bulls was carried out in spring and in summer. Three muscle samples were obtained from the longissimus dorsi and gluteus medius muscles: a biopsy prior to initiation of experimental feeding (B1); another biopsy after 14 days on diet (B2); a post mortem sample at 48 h after slaughter (3) (also M. semimembranosus). Initial resting muscle glycogen concentration affected the responsiveness of glycogen to diet. The more glycogen there was initially the less glycogen increased (r=-0.678, p<0.0001). However, compared to the low energy diet the high energy diet seemed to protect cattle from potentially glycogen-depleting stressors such as high temperatures and transportation. The cattle on high energy lost 7±4.0 (se) mmol/kg and 23±3.9 mmol/kg during transportation in spring (cool weather) and in summer (hot weather), respectively, whereas the cattle on low energy diet lost 16±3.8 mmol/kg in spring and 33±4.1 mmol/kg in summer. The overall protective effect of high energy diet corresponded to 0.65 pH units. The effects of diet were reflected all the way to ultimate pH values [5.69±0.03 (high energy); 5.93±0.03 (low energy)] (p<0.0001) and residual glycogen concentrations (p<0.0001). It seems indeed that providing a diet high in energy for a couple of weeks prior to transportation to slaughter is one of the many appropriate measures to take in the fight against bovine dark-cutting.     

Some effects of residual glycogen concentration on the physical and sensory quality of normal pH beef

The aim of this study was to assess the effects of residual glycogen concentration on the physical and sensory quality of normal-pH beef. Longissimus thoracis et lumborum muscles (n=42) having ultimate pH (48 h) between 5.50 and 5.75 were excised, assayed for residual glycogen concentration and divided into three categories according to the residual glycogen concentration. The categories were ?25 mmol/kg, 25.1-49.9 mmol/kg and ? 50 mmol/kg. One half of every LTL muscle was aged for 28 days. All samples were evaluated for fresh meat colour, drip loss, shear force, thawing and frying losses and fried steak colour as well as sensory attributes of tenderness, juiciness, flavour and overall palatability. The independent significant effects of increasing residual glycogen concentration on the physical and sensory quality of normal-pH-beef were, although numerous, quite modest in magnitude. The water holding variables in the form of decreasing drip loss (p<0.061), increasing thawing loss (p<005), increasing sum of losses in thawing and frying (p<0.05), and decreasing sensory juiciness (p<0.05) were somewhat affected as were decreasing fresh meat redness (Minolta a*) (p<0.005), decreasing shear force (p<0.05) and increasing yellowness (Minolta b*) of the steak (p<0.0001). Beef of the lowest and highest glycogen category were the ones behaving slightly differently from each other, the intermediate category mostly followed the pattern of one or the other.     

Glycogen concentrations in bovine longissimus dorsi muscle

The aim of this study was to assess the effect of location within bovine longissimus dorsi (thoracis et lumborum) muscle (LTL) when determining glycogen concentration. Six locations in Angus heifers were sampled post mortem (EXP-1) and eight locations in live Charolais crossbred steers were biopsied (EXP-2). In EXP-1, there was more glycogen in the animals' left LTL (64.1±1.6 mmol/kg) versus the right LTL (57.0±1.6 mmol/kg) (P<0.05). Locations along the cranial-caudal axis within LTL did not differ in glycogen concentration. Results for EXP-2 did not confirm the sidedness effect. Instead, it showed that glycogen concentration was lower at the cranial sampling locations near the 10th rib (89±2.5 mmol/kg) than at the middle (97±2.0 mmol/kg) or caudal locations (96±1.9 mmol/kg) (P<0.005). Taking lactate accumulation into account (glycolytic potential) rendered those differences insignificant. Nevertheless, the tendency remained clear. The potential for dilution of glycogen by intramuscular fat deposits is discussed. The results indicate that one needs to be cautious in performing repeated sampling on bovine LTL.     

Capturing quality requirements of product family architecture

Software quality is one of the major issues with software intensive systems. Moreover, quality is a critical success factor in software product families exploiting shared architecture and common components in a set of products. Our contribution is the QRF (Quality Requirements of a software Family) method, which explicitly focuses on how quality requirements have to be defined, represented and transformed to architectural models. The method has been applied to two experiments; one in a laboratory environment and the other in industry. The use of the QRF method is exemplified by the Distribution Service Platform (DiSeP), the laboratory experiment. The lessons learned are also based on our experiences of applying the method in industrial settings.     

Practical output regulation for bounded linear infinite-dimensional state space systems

We develop the mathematical foundations of practical state space output regulation for bounded infinite-dimensional linear systems. By practical output regulation we mean asymptotic tracking of references and rejection of disturbances with a given accuracy. Our main results are general upper bounds for the norms perturbations to the parameters of the exosystem, the plant and a controller which achieves exact output regulation. These bounds depend explicitly on the desired tracking accuracy ε>0. In this paper, all perturbations are assumed to be bounded, additive and linear. Our results apply for both feedforward and error feedback controllers, and for arbitrary bounded uniformly continuous reference/disturbance signals.     

Survey of reliability and availability prediction methods from the viewpoint of software architecture

Many future software systems will be distributed across a network, extensively providing different kinds of services for their users. These systems must be highly reliable and provide services when required. Reliability and availability must be engineered into software from the onset of its development, and potential problems must be detected in the early stages, when it is easier and less expensive to implement modifications. The software architecture design phase is the first stage of software development in which it is possible to evaluate how well the quality requirements are being met. For this reason, a method is needed for analyzing software architecture with respect to reliability and availability. In this paper, we define a framework for comparing reliability and availability analysis methods from the viewpoint of software architecture. Our contribution is the comparison of the existing analysis methods and techniques that can be used for reliability and availability prediction at the architectural level. The objective is to discover which methods are suitable for the reliability and availability prediction of today’s complex systems, what are the shortcomings of the methods, and which research activities need to be conducted in order to overcome these identified shortcomings. The comparison reveals that none of the existing methods entirely fulfill the requirements that are defined in the framework. The comparison framework also defines the characteristics required of new reliability and availability analysis methods. Additionally, the framework is a valuable tool for selecting the best suitable method for architecture analysis. Furthermore, the framework can be extended and used for other evaluation methods as well.     

Contrast sensitivity in diabetic pregnancy

BACKGROUND: Adenosine is a potent mediator of arteriolar tone in particular during ischemia, hypoxia, and exercise. Functional disturbance of this dilatory pathway may be highly significant for the pathophysiology and pathogenesis of arterial hypertension. PATIENTS AND METHODS: Forearm blood flow (FBF) was quantified by venous occlusion plethysmography following intra-arterial infusion of adenosine at increasing doses in 13 patients with arterial hypertension (HT) and 12 age-matched normotensive controls (NT). Hyperemic peak flow was measured following 3 minutes of non-flow ischemia. RESULTS: FBF at rest was comparable in both groups and was dose-dependently increased by adenosine in both groups. In patients with HT adenosine-induced vasodilation was significantly impaired over the entire dose-response curve compared with NT (6.0 mumol/min: 14.5 +/- 1.0 versus 8.6 +/- 0.9 ml.min-1.100 ml-1 of tissue, p < 0.01). Maximum forearm blood flow during reactive hyperemia was also profoundly impaired in the hypertensive patients (-38%, p < 0.01). In the overall group of normotensive and hypertensive subjects, flow responses to adenosine were i) significantly correlated with peak flow (adenosine 2.0 mumol/min: r = 0.79, p < 0.001), and total flow during reactive hyperemia and ii) inversely related to the magnitude of arterial blood pressure. CONCLUSIONS: The study reported presents first evidence that adenosine-dependent dilation of forearm resistance arteries is impaired in patients with arterial hypertension. This vascular dysfunction is associated with the impairment of ischemia-induced reactive hyperemia which in turn may contribute to progressive end-organ damage in arterial hypertension.     

An active single-chain antibody containing a cellulase linker domain is secreted by Escherichia coli

Single-chain antibodies consist of the variable, antigen-bindingdomains of antibodies joined to a continuous polypeptide bygenetically engineered peptide linkers. We have used the flexibleinterdomain linker region of a fungal cellulase to link togetherthe variable domains of an anti-2-phenyloxazolone IgGl and showhere that the resulting single-chain antibody is efficientlysecreted and released to the culture medium of Escherichia coli.The yield of affinity-purified single-chain antibody is 1 -2mg/1 of culture medium and its affinity and stability are comparableto those of the corresponding native IgG.