Isolation and partial characterization of two porcine spleen ferritin fractions with different electrophoretic mobility

Ferritin isolated from porcine spleen could routinely be separated in two fractions on nondenaturating gradient gels. Both fractions could be isolated with a purity of 96% when applied to two serially linked columns, each 200 cm in length, packed respectively with Sepharose 4B and Sepharose 6B. Both fractions were similar as judged by electron microscopy. Assessed biochemically fractions were equal with respect to subunit composition, iron and phosphorus content, as well as amino acid composition (with the exception of N-acetylglucosamine). Carbohydrate analysis showed that the fraction with an apparent mass of 440 kDa (=FFL) contained 1.8% (w/w) glycans, whereas the fraction with an apparent mass of 670 kDa (=FFH) contained nearly five times as much (neutral) sugar residues (8.9%, w/w) and 10 times as much sialic acid. This difference in amount of carbohydrate side chains might explain the dissimilarity in electrophoretic mobility of the two fractions

Churn, Baby, Churn: Strategic Dynamics Among Dominant and Fringe Firms in a Segmented Industry

This paper integrates and extends the literatures on industry evolution and dominant firms to develop a dynamic theory of dominant and fringe competitive interaction in a segmented industry. It argues that a dominant firm, seeing contraction of growth in its current segment(s), enters new segments in which it can exploit its technological strengths, but that are sufficiently distant to avoid cannibalization. The dominant firm acts as a low-cost Stackelberg leader, driving down prices and triggering a sales takeoff in the new segment. We identify a “churn” effect associated with dominant firm entry: fringe firms that precede the dominant firm into the segment tend to exit the segment, while new fringe firms enter, causing a net increase in the number of firms in the segment. As the segment matures and sales decline in the segment, the process repeats itself. We examine the predictions of the theory with a study of price, quantity, entry, and exit across 24 product classes in the desktop laser printer industry from 1984 to 1996. Using descriptive statistics, hazard rate models, and panel data methods, we find empirical support for the theoretical predictions

Further Evidence of Neuroprotective Effects of Recombinant Human Erythropoietin and Growth Hormone in Hypoxic Brain Injury in Neonatal Mice

Experimental in vivo data have recently shown complementary neuroprotective actions of rhEPO and growth hormone (rhGH) in a neonatal murine model of hypoxic brain injury. Here, we hypothesized that rhGH and rhEPO mediate stabilization of the blood–brain barrier (BBB) and regenerative vascular effects in hypoxic injury to the developing brain. Using an established model of neonatal hypoxia, neonatal mice (P7) were treated i.p. with rhGH (4000 µg/kg) or rhEPO (5000 IU/kg) 0/12/24 h after hypoxic exposure. After a regeneration period of 48 h or 7 d, cerebral mRNA expression of Vegf-A, its receptors and co-receptors, and selected tight junction proteins were determined using qRT-PCR and ELISA. Vessel structures were assessed by Pecam-1 and occludin (Ocln) IHC. While Vegf-A expression increased significantly with rhGH treatment (p < 0.01), expression of the Vegfr and TEK receptor tyrosine kinase (Tie-2) system remained unchanged. RhEPO increased Vegf-A (p < 0.05) and Angpt-2 (p < 0.05) expression. While hypoxia reduced the mean vessel area in the parietal cortex compared to controls (p < 0.05), rhGH and rhEPO prevented this reduction after 48 h of regeneration. Hypoxia significantly reduced the Ocln+ fraction of cortical vascular endothelial cells. Ocln signal intensity increased in the cortex in response to rhGH (p < 0.05) and in the cortex and hippocampus in response to rhEPO (p < 0.05). Our data indicate that rhGH and rhEPO have protective effects on hypoxia-induced BBB disruption and regenerative vascular effects during the post-hypoxic period in the developing brain

Industry dynamics, technological regimes and the role of demand

In this paper, we propose an industrial dynamics model to analyze the interactions between the price-performance sensitivity of demand, the sources of innovation in a sector, and certain features of the corresponding pattern of industrial transformation. More precisely, we study market concentration in different technological regimes and demand conditions. The computational analysis of our model shows that market demand plays a key role in industrial dynamics. Thus, although for intermediate values of the price-performance sensitivity, our results show the well-known relationships in the literature between technological regimes and industry transformation, we find surprising outcomes when demand is strongly biased either towards price or performance. Hence, for different technological regimes, a high performance sensitivity of demand tends to concentrate the market. On the other hand, under conditions of high price sensitivity, the industry generally tends to atomize. That is to say, for extreme values of the price-performance sensitivity of demand, we find concentrated or atomized market structures no matter the technological regime we are in. These results highlight the importance of considering the role of demand in the analysis of industrial dynamics

Hydrogen minority ion cyclotron resonance heating in presence of the iter-like wall in jet

The most recent JET campaign has focused on characterizing operation with the "ITER-like" wall. One of the questions that needed to be answered is whether the auxiliary heating methods do not lead to unacceptably high levels of impurity influx, preventing fusion-relevant operation. In view of its high single pass absorption, hydrogen minority fundamental cyclotron heating in a deuterium plasma was chosen as the reference wave heating scheme in the ion cyclotron domain of frequencies. The present paper discusses the plasma behavior as a function of the minority concentration X[H] in L-mode with up to 4MW of RF power. It was found that the tungsten concentration decreases by a factor of 4 when the minority concentration is increased from X[H] ≈ 5% to X[H] % 20% and that it remains at a similar level when X[H] is further increased to 30%; a monotonic decrease in Beryllium emission is simultaneously observed. The radiated power drops by a factor of 2 and reaches a minimum at X[H] ≈ 20%. It is discussed that poor single pass absorption at too high minority concentrations ultimately tailors the avoidance of the RF induced impurity influx. The edge density being different for different minority concentrations, it is argued that the impact ICRH has on the fate of heavy ions is not only a result of core (wave and transport) physics but also of edge dynamics and fueling

Electrical cardioversion during pregnancy: safe or not?

Two pregnant patients with a sustained symptomatic maternal supraventricular arrhythmia are presented. Both patients were treated with direct-current cardioversion. Electrical cardioversion during pregnancy is a rarely applied but highly effective procedure in the treatment of maternal cardiac arrhythmias and is assumed safe for both mother and child. However, once foetal viability is reached, monitoring of the foetal heart rate is advised and facilities for immediate caesarean section should be available

Product innovation and population dynamics in the German insurance market

Empirical research in organizational ecology has mainly focused on analyzing founding and mortality rates using life history data of the organizations. We try to extend this approach in our study in a number of ways. In contrast to most empirical studies in organizational ecology, we chose a population of service organizations, in particular the German insurance companies, the development dynamics of which are rather obvious in the innovative activities of existing organizations than in founding activities. We further discuss the points of contact between the organizational ecology approach and the theory of industry life cycles and extend the analysis to the relationship between innovative activities and population dynamics. The study examines the effects of population density, former events, and organizational size and age structure in the population of property & casualty insurance companies on the number of product innovations generated. We will further develop a concept for an insurance specific industry life cycle with a non-typical maturation and degeneration phase