Showing papers by "Stockholm University published in 1997"

The value of the world's ecosystem services and natural capital

Abstract: The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earth's life-support system. They contribute to human welfare, both directly and indirectly, and therefore represent part of the total economic value of the planet. We have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations. For the entire biosphere, the value (most of which is outside the market) is estimated to be in the range of US$16-54 trillion (10^(12)) per year, with an average of US$33 trillion per year. Because of the nature of the uncertainties, this must be considered a minimum estimate. Global gross national product total is around US$18 trillion per year.

Identification of prokaryotic and eukaryotic signal peptides and prediction of their cleavage sites.

Abstract: We have developed a new method for the identification of signal peptides and their cleavage sites based on neural networks trained on separate sets of prokaryotic and eukaryotic sequence. The method performs significantly better than previous prediction schemes and can easily be applied on genome-wide data sets. Discrimination between cleaved signal peptides and uncleaved N-terminal signal-anchor sequences is also possible, though with lower precision. Predictions can be made on a publicly available WWW server.

The complete genome sequence of the gastric pathogen Helicobacter pylori

Abstract: Helicobacter pylori, strain 26695, has a circular genome of 1,667,867 base pairs and 1,590 predicted coding sequences. Sequence analysis indicates that H. pylori has well-developed systems for motility, for scavenging iron, and for DNA restriction and modification. Many putative adhesins, lipoproteins and other outer membrane proteins were identified, underscoring the potential complexity of host-pathogen interaction. Based on the large number of sequence-related genes encoding outer membrane proteins and the presence of homopolymeric tracts and dinucleotide repeats in coding sequences, H. pylori, like several other mucosal pathogens, probably uses recombination and slipped-strand mispairing within repeats as mechanisms for antigenic variation and adaptive evolution. Consistent with its restricted niche, H. pylori has a few regulatory networks, and a limited metabolic repertoire and biosynthetic capacity. Its survival in acid conditions depends, in part, on its ability to establish a positive inside-membrane potential in low pH.

Mice lacking mitochondrial uncoupling protein are cold-sensitive but not obese

Abstract: The mitochondrial uncoupling protein (UCP) in the mitochondrial inner membrane of mammalian brown adipose tissue generates heat by uncoupling oxidative phosphorylation1. This process protects against cold2 and regulates energy balance3. Manipulation of thermogenesis could be an effective strategy against obesity4–9. Here we determine the role of UCP in the regulation of body mass by targeted inactivation of the gene encoding it. We find that UCP-deficient mice consume less oxygen after treatment with a β3-adrenergic-receptor agonist and that they are sensitive to cold, indicating that their thermo-regulation is defective. However, this deficiency caused neither hyperphagia nor obesity in mice fed on either a standard or a high-fat diet. We propose that the loss of UCP may be compensated by UCP2, a newly discovered homologue of UCP; this gene is ubiquitously expressed and is induced in the brown fat of UCP-deficient mice.

Measurements* of the Cosmological Parameters Ω and Λ from the First Seven Supernovae at z ≥ 0.35

Abstract: We have developed a technique to systematically discover and study high-redshift supernovae that can be used to measure the cosmological parameters. We report here results based on the initial seven of more than 28 supernovae discovered to date in the high-redshift supernova search of the Supernova Cosmology Project. We find an observational dispersion in peak magnitudes of ? -->MB=0.27; this dispersion narrows to ?MB, corr=0.19 after correcting the magnitudes using the light-curve width-luminosity relation found for nearby (z ? 0.1) Type Ia supernovae from the Cal?n/Tololo survey (Hamuy et al.). Comparing light-curve width-corrected magnitudes as a function of redshift of our distant (z = 0.35-0.46) supernovae to those of nearby Type Ia supernovae yields a global measurement of the mass density, ?M${r M}$ -->=0.88 -->+ 0.69?0.60 for a ? = 0 cosmology. For a spatially flat universe (i.e., ?M + ?? = 1), we find ?M${r M}$ -->=0.94 -->+ 0.34?0.28 or, equivalently, a measurement of the cosmological constant, ??=0.06 -->+ 0.28?0.34 ( < 0.51 at the 95% confidence level). For the more general Friedmann-Lema?tre cosmologies with independent ?M and ??, the results are presented as a confidence region on the ?M-?? plane. This region does not correspond to a unique value of the deceleration parameter q0. We present analyses and checks for statistical and systematic errors and also show that our results do not depend on the specifics of the width-luminosity correction. The results for ??-versus-?M are inconsistent with ?-dominated, low-density, flat cosmologies that have been proposed to reconcile the ages of globular cluster stars with higher Hubble constant values.

A person-oriented approach in research on developmental psychopathology

Abstract: There is a growing acceptance of a holistic, interactionistic view in which the individual is seen as an organized whole, functioning and developing as a totality. This view emphasizes the importance of patterns of operating factors. Within this framework, a standard variable-oriented approach, focusing on the variable as the main theoretical and analytical unit, has limitations. A person-oriented approach would often be preferable, where the main theoretical and analytical unit is the specific pattern of operating factors. Such an approach is presented here, focusing on individual development and psychopathology. A brief theoretical and methodological overview is given and a classification approach is emphasized. Empirical examples concerning the longitudinal study of adjustment problems illustrate a number of issues believed to be important to development and psychopathology: problem gravitation, the significance of single variables and of patterns, the developmental study of syndromes (= typical patterns), and the detection of "white spots" in development.

Cross-language analysis of phonetic units in language addressed to infants.

Abstract: In the early months of life, infants acquire information about the phonetic properties of their native language simply by listening to adults speak. The acoustic properties of phonetic units in language input to young infants in the United States, Russia, and Sweden were examined. In all three countries, mothers addressing their infants produced acoustically more extreme vowels than they did when addressing adults, resulting in a "stretching" of vowel space. The findings show that language input to infants provides exceptionally well-specified information about the linguistic units that form the building blocks for words.

A neural network method for identification of prokaryotic and eukaryotic signal peptides and prediction of their cleavage sites.

Abstract: We have developed a new method for the identification of signal peptides and their cleavage sites based on neural networks trained on separate sets of prokaryotic and eukaryotic sequences. The method performs significantly better than previous prediction schemes, and can easily be applied to genome-wide data sets. Discrimination between cleaved signal peptides and uncleaved N-terminal signal-anchor sequences is also possible, though with lower precision. Predictions can be made on a publicly available WWW server: .

Homogenization of swedish temperature data. part i: homogeneity test for linear trends

Abstract: A new test for the detection of linear trends of arbitrary length in normally distributed time series is developed With this test it is possible to detect and estimate gradual changes of the mean value in a candidate series compared with a homogeneous reference series The test is intended for studies of artificial relative trends in climatological time series, eg an increasing urban heat island effect The basic structure of the new test is similar to that of a widely used test for abrupt changes, the standard normal homogeneity test The test for abrupt changes is found to remain unaltered after an important generalization

Illness and narrative

Abstract: The article gives a review of the last ten years' of research on illness narratives, and organises this research around certain central themes. Four aspects of illness narratives are discussed: 1. a proposed typology giving three different kinds of illness narratives - illness as narrative, narrative about illness, and narrative as illness; 2. considerations of what can be accomplished with the help of illness narratives; 3. problems connected with how illness narratives are organised; and 4. the social context of telling and its influence on the narrative. It is argued that as social scientists we can use illness narratives as a means of studying not only the world of biomedical reality, but also the illness experience and its social and cultural underpinnings.

Gender differences in episodic memory

Abstract: The relationship between gender and memory has been largely neglected by research, despite occasional studies reporting gender differences in episodic memory performance. The present study examined potential gender differences in episodic memory, semantic memory, primary memory, and priming. Five hundred thirty women and 470 men, randomly sampled from the city of Umea, Sweden, 35–80 years of age, participated in the study. There were no differences between men and women with regard to age or education, or on a measure of global intellectual functioning. As has been demonstrated previously, men outperformed women on a visuospatial task and women outperformed men on tests of verbal fluency. In addition, the results demonstrated that women consistently performed at a higher level than did men on the episodic memory tasks, although there were no differences between men and women on the tasks assessing semantic memory, primary memory, or priming. The women’s higher level of performance on the episodic memory tasks could not be fully explained by their higher verbal ability.

The betula prospective cohort study: Memory, health, and aging

Abstract: The objective of this article is to present an overview of a prospective cohort study involving a total of 3,000 subjects whose ages were 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 years when first tested. the design of the study includes three waves of data collection. the first of these waves was conducted in 1988-1990, the second in 1993-1995, and the third will be conducted in 1998-2000. One sample of 1,000 subjects in these age cohorts underwent testing in 1988-1990 (100 subjects per cohort). This sample and two additional samples were tested in 1993-1995 and will be tested again in 1998-2000. Subjects take part in extensive health and memory examinations, and interviews about social factors. the memory testing covers a wide range of memory functions. the chief objectives of the study are to (a) examine the development of health and memory in adulthood and old age; (b) determine early preclinical signs of dementia; (c) determine risk factors for dementia; and (d) assess premorbid memory func...

N2 Fixation by non-heterocystous cyanobacteria

Abstract: Many, though not all, non-heterocystous cyanobacteria can fix N2. However, very few strains can fix N2 aerobically. Nevertheless, these organisms may make a substantial contribution to the global nitrogen cycle. In this general review, N2 fixation by laboratory cultures and natural populations of non-heterocystous cyanobacteria is considered. The properties and subcellular location of nitrogenase in these organisms is described, as is the response of N2 fixation to environmental factors such as fixed nitrogen, O2 and the pattern of illumination. The integration of N2 fixation with other aspects of cell metabolism (in particular photosynthesis) is also discussed. Similarities and differences between different individual strains of non-heterocystous cyanobacteria are highlighted.

Visualization of solvation structures in liquid mixtures.

Abstract: Spatial distribution functions of atomic densities. SDFs, have been proposed as a natural starting point for analysis of local molecular structure in liquids and solutions. The local structure in these systems is often complex and this is reflected in the fact that SDFs can be difficult to visualize. Among the different methods that can be used to visualize SDFs we discuss 3D isodensity surfaces, cross-sections, and 'comic book' animations. We also discuss the possibility of a simultaneous visualization of SDFs and other 3D fields, such as the electron density. These techniques are all intended to emphasize and bring out aspects of SDFs that promote a further understanding of the local molecular structure. OpenGL-based software has been used under X-Windows to implement these techniques, and we argue that high-quality molecular graphics need not be expensive. Data from a molecular dynamics simulation of an equimolar binary mixture of water and acetonitrile have been used to illustrate the discussion.

Predictability in the large: an extension of the concept of Lyapunov exponent

Abstract: We investigate the predictability problem in dynamical systems with many degrees of freedom and a wide spectrum of temporal scales. In particular, we study the case of three-dimensional turbulence at high Reynolds numbers by introducing a finite-size Lyapunov exponent which measures the growth rate of finite-size perturbations. For sufficiently small perturbations this quantity coincides with the usual Lyapunov exponent. When the perturbation is still small compared to large-scale fluctuations, but large compared to fluctuations at the smallest dynamically active scales, the finite-size Lyapunov exponent is inversely proportional to the square of the perturbation size. Our results are supported by numerical experiments on shell models. We find that intermittency corrections do not change the scaling law of predictability. We also discuss the relation between the finite-size Lyapunov exponent and information entropy.

Glutathione transferases catalyse the detoxication of oxidized metabolites (o-quinones) of catecholamines and may serve as an antioxidant system preventing degenerative cellular processes

Abstract: o-Quinones are physiological oxidation products of catecholamines that contribute to redox cycling, toxicity and apoptosis, i.e. the neurodegenerative processes underlying Parkinson's disease and schizophrenia. The present study shows that the cyclized o-quinones aminochrome, dopachrome, adrenochrome and noradrenochrome, derived from dopamine, dopa, adrenaline and noradrenaline respectively, are efficiently conjugated with glutathione in the presence of human glutathione transferase (GST) M2-2. The oxidation product of adrenaline, adrenochrome, is less active as a substrate for GST M2-2, and more efficiently conjugated by GST M1-1. Evidence for expression of GST M2-2 in substantia nigra of human brain was obtained by identification of the corresponding PCR product in a cDNA library. Glutathione conjugation of these quinones is a detoxication reaction that prevents redox cycling, thus indicating that GSTs have a cytoprotective role involving elimination of reactive chemical species originating from the oxidative metabolism of catecholamines. In particular, GST M2-2 has the capacity to provide protection relevant to the prevention of neurodegenerative diseases.

Fennoscandian palaeoglaciology reconstructed using a glacial geological inversion model

Abstract: The evolution of ice-sheet configuration and flow pattern in Fennoscandia through the last glacial cycle was reconstructed using a glacial geological inversion model, i.e. a theoretical model that formalises the procedure of using the landform record to reconstruct ice sheets. The model uses mapped flow traces and deglacial melt-water landforms, as well as relative chronologies derived from cross-cutting striae and till lineations, as input data. Flow-trace systems were classified into four types: (i) time-transgressive wet-bed deglacial fans, (ii) time-transgressive frozen-bed deglacial fans, (iii) surge fans, and (iv) synchronous non-deglacial (event) fans. Using relative chronologies and aggregation of fans into glaciologically plausible patterns, a series of ice-sheet Configurations at different time slices was erected. A chronology was constructed through correlation with dated stratigraphical records and proxy data reflecting global ice volume. Geological evidence exists for several discrete ice-sheet configurations centred over the Scandinavian mountain range during the early Weichselian. The build-up of the main Weichselian Fennoscandian ice sheet started at approximately 70 Ka, and our results indicate that it was characterised by an ice sheet with a centre of mass located over southern Norway. This configuration had a flow pattern which is poorly reproduced by current numerical models of the Fennoscandian ice sheet. At the Last Glacial Maximum the main ice divide was located overthe Gulf of Bothnia. A major bend in the ice divide was caused by outflow of ice to the northwest over the lowest part of the Scandinavian mountain chain. Widespread areas of preserved pre-late-Weichselian landscapes indicate that the ice sheet had a frozen-bed core area, which was only partly diminished in size by inward-transgressive wet-bed zones during the decay phase.

Search for neutral heavy leptons produced in Z decays

Abstract: Weak isosinglet Neutral Heavy Leptons (m) have been searched for using data collected by the DELPHI detector corresponding to 3:3 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived m production giving monojet or acollinear jet topologies, and for long-lived m giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 ! m) of about 1:310−6 at 95% confidence level for m masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the m mass. The results are also interpreted in terms of limits for the single production of excited neutrinos.

Plastoquinol at the quinol oxidation site of reduced cytochrome bf mediates signal transduction between light and protein phosphorylation : thylakoid protein kinase deactivation by a single-turnover flash

Abstract: Redox-controlled phosphorylation of thylakoid membrane proteins represents a unique system for the regulation of light energy utilization in photosynthesis The molecular mechanisms for this process remain unknown, but current views suggest that the plastoquinone pool directly controls the activation of the kinase On the basis of enzyme activation by a pH shift in the darkness combined with flash photolysis, EPR, and optical spectroscopy we propose that activation occurs when plastoquinol occupies the quinol-oxidation (Qo) site of the cytochrome bf complex, having its high-potential path components in a reduced state A linear correlation between kinase activation and accessibility of the Qo site to plastoquinol was established by quantification of the shift in the gy EPR signal of the Rieske Fe–S center resulting from displacement of the Qo-site plastoquinol by a quinone analog Activity persists as long as one plastoquinol per cytochrome bf is still available Withdrawal of one electron from this plastoquinol after a single-turnover flash exciting photosystem I leads to deactivation of the kinase parallel with a decrease in the gz EPR signal of the reduced Rieske Fe–S center Cytochrome f, plastocyanin, and P700 are rereduced after the flash, indicating that the plastoquinol at the Qo site is limiting in maintaining the kinase activity These results give direct evidence for a functional cytochrome bf–kinase interaction, analogous to a signal transduction system where the cytochrome bf is the receptor and the ligand is the plastoquinol at the Qo site

Thermodynamics of (3+1)-dimensional black holes with toroidal or higher genus horizons

Abstract: We examine counterparts of the Reissner-Nordstr\"om\char21{}anti\char21{}de Sitter black hole spacetimes in which the two-sphere has been replaced by a surface \ensuremath{\Sigma} of constant negative or zero curvature. When horizons exist, the spacetimes are black holes with an asymptotically locally anti\char21{}de Sitter infinity, but the infinity topology differs from that in the asymptotically Minkowski case, and the horizon topology is not ${S}^{2}.$ Maximal analytic extensions of the solutions are given. The local Hawking temperature is found. When \ensuremath{\Sigma} is closed, we derive the first law of thermodynamics using a Brown-York-type quasilocal energy at a finite boundary, and we identify the entropy as one-quarter of the horizon area, independent of the horizon topology. The heat capacities with constant charge and constant electrostatic potential are shown to be positive definite. With the boundary pushed to infinity, we consider thermodynamical ensembles that fix the renormalized temperature and either the charge or the electrostatic potential at infinity. Both ensembles turn out to be thermodynamically stable, and dominated by a unique classical solution.

Relationship marketing as a paradigm shift: some conclusions from the 30R approach

Abstract: Stresses issues brought up in the first World Wide Web conference on relationship marketing. Based on research on relationship marketing going back to the early 1970s which resulted in the definition of 30 relationships in marketing ‐ the 30R approach. Brings up inconsistencies in marketing, among them the mix‐up between relationship marketing as a phenomenon and a term; values and ethics; practice versus theory and education; differences between Europe and the USA; and the ghost‐hunt for an unambiguous definition. Concludes that relationship marketing requires a dramatic change in marketing thinking and behaviour; it is a paradigm shift, not an add‐on to traditional marketing management.

The stable nitrogen isotope ratio as a marker of food‐web interactions and fish migration

Abstract: We used stable nitrogen isotopes to describe the pelagic food-web structure of three coastal Baltic Sea areas, each of which was sampled twice. Two of the areas were influenced by 15N-rich nutrient discharges from a sewage treatment plant. Analyses were made of particulate organic matter (<35 μm, mainly phytoplankton), zooplankton, mysids (Mysis mixta and M. relicta), sprat (Sprattus sprattus), smelt (Osmerus eperlanus), four size classes of herring (Clupea harengus), and pikeperch (Stizostedion lucioperca). Discharges from the sewage treatment plant significantly increased δ15N values in the whole food web, from phytoplankton to piscivorous fish. Based on nitrogen isotopic compositions, consistent trophic food-web structures were observed on both occasions and in all three areas. The results indicate that zooplankton and mysids may have more complex diets than assumed before. Apparent trophic fractionation, i.e., differences in δ15N between a consumer and its assumed food, averaged 2.4‰ with a standard e...

Thioglycosides as glycosyl donors in oligosaccharide synthesis.

Abstract: Publisher Summary This chapter analyzes the importance of thioclycosides as the glycosyl donors in oligosaccharide synthesis. The presence and biological importance of oligosaccharide structures, usually as the components of glycolipids and glycoproteins, in bacterial capsular and cell-wall polysaccharides, in mammalian cell membranes, in cytoplasm, and in extra-cellular fluids are well documented. Acylated glycosyl thiocyanates are made by the treatment of acylated glycopyranosyl halides with potassium thiocyanate. An attractive feature of thioglycosides as the glycosyl donors in oligosaccharide synthesis is that they are readily converted into all of the other glycosyl donors. The glycosyl bromide can also be converted into a 4-pentenyl glycoside, which becomes a glycosyl donor by promotion with an iodonium compound. Tris(4-bromophenyl)ammoniurnyl hexachloroantimonate (TBPA) differs from the other promoters in the context that its cation is a radical and produces radical cationic sulfonium ions such as glycosylating species from thioglycosides. In acetonitrile as solvent, and with a nonparticipating 2-substituent in the glycosyl donor, 1,2-trans glycosides are formed as a result of solvent participant. The transfer of the Armed–Disarmed concept to thioglycoside glycosylation reactions is also elaborated in the chapter.

Identification and Quantification of Polybrominated Diphenyl Ethers and Methoxy-Polybrominated Diphenyl Ethers in Baltic Biota

Abstract: Polybrominated diphenyl ethers (PBDPEs) and, for the first time, methoxy-polybrominated diphenyl ethers (MeO-PBDPEs) have been positively identified and quantified in various biotic samples including herring, salmon, seal, man (only PBDPEs), and commercial fish oils. The presence of these compounds was confirmed in the above samples by mass spectra and accurate mass determinations and verified by comparisons to gas chromatography− mass spectrometry (GC−MS) of available reference material. Concentrations were measured by GC−MS and found to vary from the low to moderate nanogram per gram of lipid range, with the highest levels in seal blubber and salmon muscle. Data for the studied samples suggest that these compounds bioconcentrate. The presence of polychlorinated diphenyl ethers and methoxy polychlorinated diphenyl ethers was indicated in a screened seal tissue. Potential environmental sources of the MeO-PBDPEs are discussed.

Hemoglobin Adducts of Acrylamide and Acrylonitrile in Laboratory Workers, Smokers and Nonsmokers

Abstract: Acrylamide is a chemical which is extensively used in research laboratories for the preparation of polyacrylamide gels for electrophoresis (PAGE). Blood samples were collected from laboratory personnel who were working with PAGE, from smokers, and from nonsmokers. Hemoglobin adducts of acrylamide, acrylonitrile, and ethylene oxide were determined using the modified Edman degradation procedure. Acrylamide adducts were detected in all persons. The PAGE workers (mean 54 pmol/g) had a significantly increased adduct level compared to nonsmoking controls (mean 31 pmol/g). The acrylamide adducts in smokers (mean 116 pmol/g) correlated with the number of cigarettes smoked per day. This confirms the presence of acrylamide in tobacco smoke and shows that it is an important source of acrylamide exposure. The increased level of acrylamide adducts in the PAGE workers corresponds to an uptake of acrylamide from about 3 cigarettes per day. It is not possible from this study to draw any conclusion as to which step in the working procedure is most critical for exposure. The PAGE workers are probably not at risk for neurotoxic damage to the peripheral nervous system. However, it needs to be investigated whether the exposure to acrylamide in PAGE workers represents a risk for genotoxic and reproductive effects. The high background of acrylamide adducts in nonsmoking controls was unexpected. The origin of this background is not known. Acrylonitrile adducts were below the detection limit (< 2 pmol/g) in nonsmoking controls. In the smokers (mean 106 pmol/g) this adduct correlated with cigarettes/day and with ethylene oxide adducts. Acrylonitrile adducts could be a better indicator of tobacco smoking than ethylene oxide adducts since the latter are showing a background of endogenous origin.

Total Volatile Organic Compounds (TVOC) in Indoor Air Quality Investigations

Abstract: The amount of volatile organic compounds (VOCs) in indoor air, usually called TVOC (total volatile organic compounds), has been measured using different definitions and techniques which yield different results. This report recommends a definition of TVOC referring to a specified range of VOCs and it proposes a method for the measurement of this TVOC entity. Within the specified range, the measured concentrations of identified VOCs (including 64 target compounds) are summed up, concentrations of non-identified compounds in toluene equivalents are added and, together with the identified VOCs, they give the TVOC value. The report reviews the TVOC concept with respect to its usefulness for exposure assessment and control and for the prediction of health or comfort effects. Although the report concludes that at present it is not possible to use TVOC as an effect predictor, it affirms the usefulness of TVOC for characterizing indoor pollution and for improving source control as required from the points of view of health, comfort, energy efficiency and sustainability.