Showing papers by "Uppsala University published in 1999"

Localised Learning and Industrial Competitiveness

Abstract: Introduction: Towards the knowledge-based economy Knowledge creation Limits to learning Regional capabilities, institutions and localised learning. Enhanced knowledge creation: industrial districts

Poleward shifts in geographical ranges of butterfly species associated with regional warming

Abstract: Mean global temperatures have risen this century, and further warming is predicted to continue for the next 50-100 years(1-3) Some migratory species can respond rapidly to yearly climate variation ...

A simple and universal method for molecular sexing of non-ratite birds

Abstract: Molecular sexing is an attractive means to determine the sex of sexually monomorphic birds, e.g. chicks of most species. A universal approach for molecular sexing of birds would require that a conserved W chromosome-linked sequence could be analysed, but no single gene has previously been known from any avian W chromosome. The recent discovery of the CHD1W gene, apparently W-linked in all non-ratite birds, has opened new possibilities in this direction, although there is a problem in that the gene also exists in a very similar copy on the Z chromosome (CHD1Z). Here we describe a universal method for molecular sexing of non-ratite birds which is based on the detection of a constant size difference between CHD1W and CHD1Z introns. Using highly conserved primers flanking the intron, PCR amplification and agarose electrophoresis, females are characterised by displaying one (CHD1W) or two fragments (CHD1W and CHD1Z), while males only show one fragment (CHD1Z) clearly different in size from the female-specific CHD1W fragment. With one particular pair of primers (2550F and 2718R) we applied this test to 50 bird species from 11 orders throughout the avian phylogeny, successfully sexing 47 of the species. Using an alternative pair of primers, the three failing species could be reliably sexed. This means that a simple, rapid and cheap universal system for molecular sexing of non-ratite birds is now available.

Silver-based crystalline nanoparticles, microbially fabricated

Abstract: One mechanism of silver resistance in microorganisms is accumulation of the metal ions in the cell. Here, we report on the phenomenon of biosynthesis of silver-based single crystals with well-defined compositions and shapes, such as equilateral triangles and hexagons, in Pseudomonas stutzeri AG259. The crystals were up to 200 nm in size and were often located at the cell poles. Transmission electron microscopy, quantitative energy-dispersive x-ray analysis, and electron diffraction established that the crystals comprise at least three different types, found both in whole cells and thin sections. These Ag-containing crystals are embedded in the organic matrix of the bacteria. Their possible potential as organic-metal composites in thin film and surface coating technology is discussed.

The gene encoding ribosomal protein S19 is mutated in Diamond-Blackfan anaemia

Abstract: Diamond-Blackfan anaemia (DBA) is a constitutional erythroblastopenia characterized by absent or decreased erythroid precursors. The disease, previously mapped to human chromosome 19q13, is frequently associated with a variety of malformations. To identify the gene involved in DBA, we cloned the chromosome 19q13 breakpoint in a patient with a reciprocal X;19 chromosome translocation. The breakpoint occurred in the gene encoding ribosomal protein S19. Furthermore, we identified mutations in RPS19 in 10 of 40 unrelated DBA patients, including nonsense, frameshift, splice site and missense mutations, as well as two intragenic deletions. These mutations are associated with clinical features that suggest a function for RPS19 in erythropoiesis and embryogenesis.

Heritable variation and evolution under favourable and unfavourable conditions.

Abstract: Genetic variability in quantitative traits can change as a direct response to the environmental conditions in which they are expressed. Consequently, similar selection in different environments might not be equally effective in leading to adaptation. Several hypotheses, including recent ones that focus on the historical impact of selection on populations, predict that the expression of genetic variation will increase in unfavourable conditions. However, other hypotheses lead to the opposite prediction. Although a consensus is unlikely, recent Drosophila and bird studies suggest consistent trends for morphological traits under particular conditions.

The Lorenz attractor exists

Abstract: We prove that the Lorenz equations support a strange attractor, as conjectured by Edward Lorenz in 1963. We also prove that the attractor is robust, i.e., it persists under small perturbations of the coefficients in the underlying differential equations. The proof is based on a combination of normal form theory and rigorous numerical computations.

Creating value through mutual commitment to business network relationships

Abstract: A structural model of business relationship development in a business network context is formulated and tested on delta from the European International Marketing and Purchasing (IMP) project. The e ...

The Competitiveness of Firms and Regions: ‘Ubiquitification’ and the Importance of Localized Learning

Abstract: In traditional location theory there is a distinction between factors of production for which the costs differ significantly between locations, on the one hand, and production inputs which are in practice available everywhere at more or less the same cost (i.e. so-called ubiquities) on the other.In this article, we discuss the process whereby some previously important location factors are actively converted into ubiquities. With an admittedly rather horrendous term, we label this process ‘ubi-quitification’. It is argued that ubiquitification is the outcome of the ongoing globalization process as well as of a process whereby former tacit knowledge gradually becomes codified.Ubiquitification tends to undermine the competitiveness of firms in the high-cost areas of the world. When international markets are opened up and when knowledge of the latest production technologies and organizational designs become globally available, firms in low-cost areas become more competitive. In a knowledge-based economy, as a...

Dye-Sensitized Nanostructured p-Type Nickel Oxide Film as a Photocathode for a Solar Cell

Abstract: Nanostructured NiO film was prepared by depositing nickel hydroxide slurry on conducting glass and sintering at 500 °C to a thickness of about 1 μm. The photocurrent−voltage (IV) characteristics of the plain nanostructured NiO electrode recorded potentiostatically in a standard three-electrode setup upon UV illumination demonstrate p-type behavior, while the IV characteristics of a dye-sensitized nanostructured NiO electrode coated with erythrosin B show cathodic photocurrent under visible light illumination. The highest incident photon-to-current conversion efficiencies of tetrakis(4-carboxyphenyl)porphyrin (TPPC) and erythrosin B-coated NiO films were 0.24% and 3.44%, respectively. In sandwich solar cells with a platinized conducting glass as counter electrode exposed to light from a sun simulator (light intensity: 68 mW/cm2), a short-circuit cathodic photocurrent density (ISC) of 0.079 mA/cm2 and an open-circuit voltage (VOC) of 98.5 mV for TPPC-coated NiO electrode were achieved. Similarly, ISC = 0.2...

Abnormal mast cells in mice deficient in a heparin-synthesizing enzyme

Abstract: Heparin is a sulphated polysaccharide, synthesized exclusively by connective-tissue-type mast cells1 and stored in the secretory granules in complex with histamine and various mast-cell proteases2. Although heparin has long been used as an antithrombotic drug, endogenous heparin is not present in the blood, so it cannot have a physiological role in regulating blood coagulation. The biosynthesis of heparin involves a series of enzymatic reactions, including sulphation at various positions1,3. The initial modification step, catalysed by the enzyme glucosaminyl N -deacetylase/N -sulphotransferase-2, NDST-2 (4–7), is essential for the subsequent reactions. Here we report that mice carrying a targeted disruption of the gene encoding NDST-2 are unable to synthesize sulphated heparin. These NDST-2-deficient mice are viable and fertile but have fewer connective-tissue-type mast cells; these cells have an altered morphology and contain severely reduced amounts of histamine and mast-cell proteases. Our results indicate that one site of physiological action for heparin could be inside connective-tissue-type mast cells, where its absence results in severe defects in the secretory granules.

Improved glycemic control and lipid profile and normalized fibrinolytic activity on a low-glycemic index diet in type 2 diabetic patients.

Abstract: OBJECTIVE: To evaluate the effects of varying the glycemic index (GI) of carbohydrate-rich foods on metabolic control in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: In a randomized crossover study, 20 patients, 5 women and 15 men, were given preweighed diets with different GIs during two consecutive 24-day periods. Both diets were composed in accordance with dietary recommendations for people with diabetes. The macronutrient composition and type and amount of dietary fiber were identical. Differences in GI were achieved mainly by altering the structure of the starchy foods. RESULTS: Peripheral insulin sensitivity increased significantly and fasting plasma glucose decreased during both treatment periods. There was a significant difference in the changes of serum fructosamine concentrations between the diets (P

From GCMs to river flow: a review of downscaling methods and hydrologic modelling approaches

Abstract: The scientific literature of the past decade contains a large number of reports detailing the development of downscaling methods and the use of hydrologic models to assess the potential effects of climate change on a variety of water resource issues. This article reviews the current state of methodologies for simulating hydrological responses to global climate change. Emphasis is given to recent advances in climatic downscaling and the problems related to the practical application of appropriate models in impact studies. Following a discussion of the advantages and deficiencies of the various approaches, challenges for the future study of the hydrological impacts of climate change are identified.

Origin of the Invar effect in iron–nickel alloys

Abstract: In 1897 Guillaume1 discovered that face-centred cubic alloys of iron and nickel with a nickel concentration of around 35 atomic per cent exhibit anomalously low (almost zero) thermal expansion over a wide temperature range. This effect, known as the Invar effect, has since been found in various ordered and random alloys and even in amorphous materials2. Other physical properties of Invar systems, such as atomic volume, elastic modulus, heat capacity, magnetization and Curie (or Neel) temperature, also show anomalous behaviour. Invar alloys are used in instrumentation, for example as hair springs in watches. It has long been realized that the effect is related to magnetism2,3; but a full understanding is still lacking. Here we present ab initio calculations of the volume dependences of magnetic and thermodynamic properties for the most typical Invar system, a random face-centred cubic iron–nickel alloy, in which we allow for non-collinear spin alignments—that is, spins that may be canted with respect to the average magnetization direction. We find that the magnetic structure is characterized, even at zero temperature, by a continuous transition from the ferromagnetic state at high volumes to a disordered non-collinear configuration at low volumes. There is an additional, comparable contribution to the net magnetization from the changes in the amplitudes of the local magnetic moments. The non-collinearity gives rise to an anomalous volume dependence of the binding energy, and explains other peculiarities of Invar systems.

Signal transduction by fibroblast growth factor receptors.

Abstract: The fibroblast growth factor family, with its prototype members acidic FGF (FGF-1) and basic FGF (FGF-2), binds to four related receptor tyrosine kinases, expressed on most types of cells in tissue culture. In many respects, the FGF receptors appear similar to other growth factor receptors. Thus, dimerization of receptor monomers upon ligand binding is likely to be a requisite for activation of the kinase domains, leading to receptor trans phosphorylation. FGF receptor-1 (FGFR-1), which shows the broadest expression pattern of the four FGF receptors contains at least seven tyrosine phosphorylation sites. A number of signal transduction molecules are affected by binding with different affinities to these phosphorylation sites. The potential roles of these signal transduction molecules in FGF-induced biological responses and in pathological processes are discussed.

Breast-cancer risk following long-term oestrogen- and oestrogen-progestin-replacement therapy.

Abstract: While use of hormone-replacement therapy (HRT) effectively alleviates menopausal symptoms and prevents osteoporosis and possibly cardiovascular disease, there is concern of a detrimental impact on breast-cancer risk. There is a particular lack of data regarding the effect of long-term use of oestrogen-progestin combinations on breast-cancer risk. We conducted a large epidemiological study in Sweden, where combined oestrogen-progestin treatment has been predominant, to examine the influence of different regimens of menopausal hormone therapy on breast-cancer risk. In this population-based case-control study, 3,345 women aged 50 to 74 years with invasive breast cancer (84% of all eligible) and 3,454 controls of similar age (82% of all selected) were included. Mailed questionnaires and telephone interviews were used to collect detailed information on use of hormone replacement and on potential confounding factors. Odds ratios (OR) and 95% confidence intervals (CI) were estimated through multiple logistic regression. There was a trend of increasing breast-cancer risk with duration of oestrogen/oestrogen-progestin use (OR for women treated at least 10 years, 2.43; 95% CI, 1.79-3.30, as compared to never-users), with statistically significant estimates only for women with BMI<27 kg/m2. Excess risks were observed to current use and use that ceased more than 10 years ago (OR for women treated at least 5 years, OR was 2.68, 95% CI, 2.09-3.42, and OR 2.57, 95% CI, 1.28-5.15, as compared with never-users, respectively). A positive association which was noted for use of oestrogen combined with testosterone-derived progestins appeared especially pronounced with continuously combined regimens. Long-term use of replacement oestrogens with or without progestins may substantially increase the incidence of post-menopausal breast cancer, particularly among non-obese women.

Genetic architecture of fitness and nonfitness traits: empirical patterns and development of ideas.

Abstract: Comparative studies of the genetic architecture of different types of traits were initially prompted by the expectation that traits under strong directional selection (fitness traits) should have lower levels of genetic variability than those mainly under weak stabilizing selection (nonfitness traits). Hence, early comparative studies revealing lower heritabilities of fitness than nonfitness traits were first framed in terms of giving empirical support for this prediction, but subsequent treatments have effectively reversed this view. Fitness traits seem to have higher levels of additive genetic variance than nonfitness traits — an observation that has been explained in terms of the larger number loci influencing fitness as compared to nonfitness traits. This hypothesis about the larger functional architecture of fitness than nonfitness traits is supported by their higher mutational variability, which is hard to reconcile without evoking capture of mutational variability over many loci. The lower heritabilities of fitness than nonfitness traits, despite the higher additive genetic variance of the former, occur because of their higher residual variances. Recent comparative studies of dominance contributions for different types of traits, together with theoretical predictions and a large body of indirect evidence, suggest an important role of dominance variance in determining levels of residual variance for fitness-traits. The role of epistasis should not be discounted either, since a large number of loci increases the potential for epistatic interactions, and epistasis is strongly implicated in hybrid breakdown.

Ultraviolet colour variation influences blue tit sex ratios

Abstract: Brilliant blue and violet structural colours are common plumage ornaments in birds, but their signalling functions are poorly understood1. This may be because birds also communicate in ultraviolet (UV-A) wavelengths (320–400 nm)2,3,4,5, invisible to humans, but a strong spectral component of many structural colours6. From a wild population of blue tits—Parus caeruleus, sexually dimorphic primarily in the ultraviolet7,8—we report experimental evidence that females skew the sex ratio of their offspring in response to the ultraviolet plumage ornamentation of their mates. Masking male ultraviolet reflectance reversed a positive correlation between reflectance and brood sex ratio observed in control pairs, demonstrating a causal effect of male ultraviolet ornamentation on offspring sex ratio. Ultraviolet reflectance also predicted male survival to the following breeding season, suggesting that it serves as a viability indicator. When taken together with ecological effects (laying date, nesting area), our experiments reveal that an unexpected amount of control exists over the primary sex ratio in birds, suggesting that chromosomal sex determination may not constrain the sex ratios of multiparous vertebrates.

From Dyadic Change to Changing Business Networks: An Analytical Framework

Abstract: This paper investigates the dynamics of business networks. We distinguish between confined dyadic change and network change and show how change itself may be incremental or radical, using the punctuated equilibrium model of change. The concept of the critical event is introduced to highlight radical change. We propose an analytical framework where the ideas of mechanism, nature and forces of change are integrated. Two circles of network change (incremental and radical) are presented and transfers from one circle to the other are discussed. We believe this conceptual elaboration may have significant implications for future network dynamic research

Short-Term Effects of Fights for Social Dominance and the Establishment of Dominant-Subordinate Relationships on Brain Monoamines and Cortisol in Rainbow Trout

Abstract: We report changes in brain serotonergic, noradrenergic and dopaminergic activity, along with plasma cortisol concentrations, occurring during the initial 24-h period following the establishment of dominant-subordinate relationships in pairs of rainbow trout. Immediately (within 5 min) after the termination of staged fights for social dominance, a large increase in blood plasma cortisol was observed in both fight losers (future subordinate fish) and winners (future dominant fish). In dominant fish, cortisol decreased rapidly (within 3 h) to the level of unstressed controls, while continuing to increase in subordinate fish. At 3 h following fights, the brain serotonergic system was activated in both dominant fish and subordinate fish, at least in some brain regions (telencephalon). This effect was reversed in dominant individuals within 24 h of social interaction, whereas in subordinate fish a substantial activation of the serotonergic system was manifest in all brain regions by 24 h. Similarly, a strong increase in brain catecholaminergic activation was indicated after 24 h of social interaction in subordinate fish, but not in dominant fish. Relationships between plasma cortisol and brain serotonergic and noradrenergic activity in the various experimental groups suggest that these systems influence cortisol secretion under normal conditions and during moderate or short-term stress.

Exercise Intolerance Due to Mutations in the Cytochrome b Gene of Mitochondrial DNA

Abstract: Background The mitochondrial myopathies typically affect many organ systems and are associated with mutations in mitochondrial DNA (mtDNA) that are maternally inherited. However, there is also a sporadic form of mitochondrial myopathy in which exercise intolerance is the predominant symptom. We studied the biochemical and molecular characteristics of this sporadic myopathy.Methods We sequenced the mtDNA cytochrome b gene in blood and muscle specimens from five patients with severe exercise intolerance, lactic acidosis in the resting state (in four patients), and biochemical evidence of complex III deficiency. We compared the clinical and molecular features of these patients with those previously described in four other patients with mutations in the cytochrome b gene.Results We found a total of three different nonsense mutations (G15084A, G15168A, and G15723A), one missense mutation (G14846A), and a 24-bp deletion (nucleotides 15498 to 15521) in the cytochrome b gene in the five patients. Each of these mutations impairs the enzymatic function of the cytochrome b protein. In these patients and those previously described, the clinical manifestations included progressive exercise intolerance, proximal limb weakness, and in some cases, attacks of myoglobinuria. There was no maternal inheritance and there were no mutations in tissues other than muscle. The absence of these findings suggests that the disorder is due to somatic mutations in myogenic stem cells after germ-layer differentiation. All the point mutations involved the substitution of adenine for guanine, but all were in different locations.Conclusions The sporadic form of mitochondrial myopathy is associated with somatic mutations in the cytochrome b gene of mtDNA. This myopathy is one cause of the common and often elusive syndrome of exercise intolerance. (N Engl J Med 1999; 341:1037-44.) (C)1999, Massachusetts Medical Society.

On the Benefits From Rigid Labour Markets: Norms, Market Failures, and Social Insurance

Abstract: The common view that far-reaching labour market deregulation is the only remedy for high European unemployment is too simplistic. First, the evidence suggests that deeply rooted social customs are ...