Showing papers by "Stockholm University published in 1996"

Regional nitrogen budgets and riverine N & P fluxes for the drainages to the North Atlantic Ocean: Natural and human influences

Abstract: We present estimates of total nitrogen and total phosphorus fluxes in rivers to the North Atlantic Ocean from 14 regions in North America, South America, Europe, and Africa which collectively comprise the drainage basins to the North Atlantic. The Amazon basin dominates the overall phosphorus flux and has the highest phosphorus flux per area. The total nitrogen flux from the Amazon is also large, contributing 3.3 Tg yr-1 out of a total for the entire North Atlantic region of 13.1 Tg yr-1. On a per area basis, however, the largest nitrogen fluxes are found in the highly disturbed watersheds around the North Sea, in northwestern Europe, and in the northeastern U.S., all of which have riverine nitrogen fluxes greater than 1,000 kg N km-2 yr-1.

The fate of nitrogen and phosphorus at the land-sea margin of the North Atlantic Ocean

Abstract: Five large rivers that discharge on the western North Atlantic continental shelf carry about 45% of the nitrogen (N) and 70% of the phosphorus (P) that others estimate to be the total flux of these elements from the entire North Atlantic watershed, including North, Central and South America, Europe, and Northwest Africa. We estimate that 61 · 109 moles y-1 of N and 20 · 109 moles y-1 of P from the large rivers are buried with sediments in their deltas, and that an equal amount of N and P from the large rivers is lost to the shelf through burial of river sediments that are deposited directly on the continental slope. The effective transport of active N and P from land to the shelf through the very large rivers is thus reduced to 292 · 109 moles y-1 of N and 13 · 109 moles y-1 of P.

Gender, equality, and welfare states

Abstract: What differences do welfare state variations make for women? How do women and men fare in different welfare states? Diane Sainsbury answers these questions by analysing the situation in countries whose welfare state policies differ in significant ways: the United States, the United Kingdom, Sweden, and the Netherlands. Building on feminist criticisms of mainstream research, Professor Sainsbury reconceptualises the crucial dimensions of variation, notably those relevant to gender. She determines the extent to which legislation reflects and perpetuates the gendered division of labour in the family and society, as well as what types of policy alter gender relations in social provision. She thereby increases our understanding of how policy mechanisms, especially the bases of entitlement, exclude or incorporate women and offers constructive proposals for securing greater equality between women and men.

Barbero's Hamiltonian derived from a generalized Hilbert-Palatini action

Abstract: Barbero recently suggested a modification of Ashtekar's choice of canonical variables for general relativity. Although leading to a more complicated Hamiltonian constraint this modified version, in which the configuration variable still is a connection, has the advantage of being real. In this article we derive Barbero's Hamiltonian formulation from an action, which can be considered as a generalization of the ordinary Hilbert-Palatini action.

A new intermolecular interaction: unconventional hydrogen bonds with element-hydride bonds as proton acceptor.

Abstract: This Account describes a new type of intermolecular interaction, the H‚‚‚H or dihydrogen bond, which operates between a conventional hydrogen bond donor such as an NH or OH bond as the weak acid component and an element-hydride bond as the weak base component, where the element in question can be a transition metal or boron. The interaction, which involves a close approach of protonic and hydridic hydrogens, has been characterized by crystallography, including neutron diffraction, and by physical and theoretical methods. These interactions occur in the so-called second or outer coordination sphere of a metal complex, as distinct from the first or inner sphere of the ligands directly bound to the metal. Taube1 has drawn attention to the importance of the outer solvent sphere in certain electron transfer processes, but otherwise very little is known about the structure and energetics of the outer sphere, and little attention2 has been given to the possibility of its control and organization. By selectively stabilizing the transition state, such interactions might be capable of accelerating specific reactions and so provide a general strategy with useful applications in catalysis. Conventional hydrogen bonds are formed between a proton donor, such as an OH or NH group, and a proton acceptor, such as an oxygen or nitrogen lone pair,3 but in all such cases a nonbonding electron pair acts as the weak base component. In rare cases, π-bonds4 and even metal atoms in metal complexes5 have also been shown to act as weak proton acceptors. A wide variety of element-hydrogen σ bonds, such as B-H and M-H (M ) transition metal), act as unexpectedly efficient hydrogen bond acceptors toward conventional proton donors, such as O-H and N-H groups. The resulting E-H‚‚‚H-X systems have close H‚‚‚H contacts (1.75-1.9 Å) and they have therefore been termed “H‚‚‚H or dihydrogen bonds”.6 Their heats of interaction are substantial (3-7 kcal mol-1) and lie in the range found for conventional H-bonds. Both interand intramolecular versions have been identified, and a number of reactions involving these new H-bonds have also been found. A significant feature of the work has been the close cooperation among synthetic, physical, crystallographic, and theoretical approaches.

The human gene FALL39 and processing of the cathelin precursor to the antibacterial peptide LL-37 in granulocytes

Abstract: The peptide FA-LL-37, previously termed FALL-39, was originally predicted from on ORF of a cDNA clone isolated from a human bone marrow library. This peptide was synthesized and found to have antibacterial activity. We have now characterized and sequenced the complete gene for FA-LL-37, termed FALL39. It is a compact gene of 1963 bp with four exons. Exons 1-3 code for a signal sequence and the cathelin region. Exon 4 contains the information for the mature antibacterial peptide. Our results indicate that FALL39 is the only member of the cathelin gene family present in the human genome. Potential binding sites for acute-phase-response factors are identified in the promoter and in intron 2. A possible role for the cytokine interleukin-6 in the regulation of FALL 39 is discussed. Anti-(FA-LL-37) IgG located the peptide in granulocytes and we isolated the mature peptide from these cells after degranulation. Structural analysis determined the mature peptide to be LL-37. To obtain LL-37 for antibacterial assays, synthetic FA-LL-37 was degraded with dipeptidyl-peptidase I. This analysis showed that mature LL-37 is a potent antibacterial peptide.

Assessing reliability of a measure of self-rated health

Abstract: The test-retest reliability of self-rated health is analysed and compared with the reliability of health questions phrased more as well as less precisely. Differences in reliability between men and women and between age groups are also assessed. The study is based on 204 and 409 re-interviews from the 1991 Swedish Level of Living Survey and the 1989 Survey of Living Conditions respectively. The results show that the reliability of self-rated health is as good as or even better than that of most of the more specific questions. Only an indicator of high blood pressure showed significantly higher reliability. The reliability of self-rated health is good in all subgroups studied, and is even excellent among older men. It is concluded that the good overall reliability of self-rated health found in this study is in line with previous results concerning the validity of people's assessments of their general health as well as results concerning the basis upon which they make these judgements.

The comet assay: mechanisms and technical considerations.

Abstract: The comet assay is frequently used to measure DNA damage in individual cells. In order to better understand the mechanisms behind the technique, we have studied the behaviour of DNA under different electrophoresis conditions in mammalian cells exposed to gamma irradiation. The comet tails obtained after neutral electrophoresis seem to consist of DNA loops which are attached to structures in the nucleus, since the DNA cannot move in the second direction after two-dimensional electrophoresis. When the DNA is labelled by a short pulse, microautoradiography reveals that all label appear in the head of the comets when neutral electrophoresis is applied. After chase incubation, the label moves out into the tails. This gives further support to the view that the DNA loops are fixed to some structure in the nucleus where also the DNA synthesis takes place. Under alkaline electrophoresis conditions, however, the entire comet tails move in the new electrophoresis direction. Thus, it appears that the alkaline comet tails consist of free DNA fragments. Further, the effects of alkaline concentration and sodium chloride during unwinding and electrophoresis are discussed. Throughout the study, a protocol for drying and fixation of the comets has been used.

Economic Growth, Carrying Capacity, and the Environment

Abstract: Nat iona l and international economic policy has usually ignored the environment. In areas where the environment is beginning to impinge on policy, as in the General Agreement on Tariffs and Trade (GATT) and the North American Free Trade Agreement (NAFTA), it remains a tangential concern, and the presumption is often made that economic growth and economic liberalization (including the liberalization of intemational trade) are, in some sense, good for the environment. This notion has meant that economy-wide policy reforms designed to promote growth and liberalization have been encouraged with little regard to their environmental consequences, presumably on the assumption that these consequences would either take care of themselves or could be dealt with separately. In this article we discuss the relation between economic growth and environmental quality, and the link between economic activity and the carrying capacity and resilience of the environment (1).

Functional morphology and homology in the odontocete nasal complex: implications for sound generation

Abstract: The site and physiologic mechanism(s) responsible for the generation of odontocete biosonar signals have eluded investigators for decades. To address these issues we subjected postmortem toothed whale heads to interrogation using medical imaging techniques. Most of the 40 specimens (from 19 species) were examined using x-ray computed tomography (CT) and/or magnetic resonance imaging (MR). Interpretation of scan images was aided by subsequent dissection of the specimens or, in one case, by cryosectioning. In all specimens we described a similar tissue complex and identified it as the hypothetical biosonar signal generator. This complex includes a small pair of fatty bursae embedded in a pair of connective tissue lips, a cartilaginous blade, a stout ligament, and an array of soft tissue air sacs. Comparing and contrasting the morphologic patterns of nasal structures across species representing every extant odontocete superfamily reveals probable homologous relationships, which suggests that all toothed whales may be making their biosonar signals by a similar mechanism.

The customer as co‐producer

Abstract: Buyer‐seller interaction in industrial markets is a widely applied work logic, which has been thoroughly researched both empirically and theoretically. Addresses, in contrast,the interactive way of working in consumer markets, which is referred to increasingly under the heading of “customer co‐production”. Results indicate that company‐consumer interaction is becoming more frequent in a wide range of consumer industries, but in contrast to such interaction in industrial markets it generally encompasses only one or two of the value‐creating activities of design, production or consumption, and the benefits are mostly short‐term: a better fit for the consumers and the advantage of more differentiated offerings for the companies. However, the strategic benefits of learning that enhance the innovative capability of the producers and add to the competence of the users, still seem limited. One reason for this may be lack of channels for feedback, since it is the front‐line staff who interact with the consumers. Also, they lack the authority and competence for undertaking the feedback role. A growing population of advanced consumers, flexible production modes and the widespread application of information technology all help to create a potential for this logic, but in order to exploit its benefits to the full, more knowledge is needed about how to organize the interaction with a view to learning.

Biological Diversity, Ecosystems, and the Human Scale

Abstract: This paper considers the significance of biological diversity in relation to large-scale processes in complex and dynamic ecological-economic systems. It focuses on functional diversity, and its relation to production and maintenance of ecological services that underpin human societies. Within functional groups of organisms two important cat- egories of species are identified: keystone process species and those essential for ecosystem resilience. The latter group represents "natural insurance capital." In addition to basic research on the interplay among biological diversity, functional performance, and resilience in complex self-organizing systems, we suggest that a functional approach has two main implications for a strategy for biodiversity conservation: (1) Biodiversity conservation to assure the resilience of ecosystems is required for all systems, no matter how heavily impacted they are. It should not be limited to protected areas. (2) The social, cultural, and economic driving forces in society that cause biodiversity loss need to be addressed directly. Specifically, (a) differences between the value of biological diversity to the private indi- vidual and its fundamental value to society as a whole need to be removed; (b) social and economic policies that encourage biodiversity loss should be reformed, especially where there is a risk of irreversible damage to ecosystems and diversity; and (c) institutions that are adaptive and work in synergy with ecosystem processes and functions are critical and should be created at all levels.

Activation of medial temporal structures during episodic memory retrieval.

Abstract: Medial temporal lobe structures have been implicated in human episodic memory. Patients with medial temporal lesions show memory deficits, and functional neuroimaging studies have revealed activation in this region during episodic encoding and retrieval when data are averaged over a sample of subjects. The relevance of such observations for memory performance has remained unclear, however. Here we have used positron emission tomography (PET) to examine cerebral blood flow related to verbal episodic retrieval. We observed strong positive correlations between retrieval and blood flow in left medial temporal structures in individual normal human subjects. In addition, multivariate analysis showed that regions in the left medial temporal lobe were dominant components of a pattern of brain regions that distinguished a high-retrieval condition from conditions of lower retrieval. These results suggest that medial temporal activity is related to retrieval success rather than retrieval attempt, possibly by reflecting reactivation of stored patterns.

Origins of immunity: Relish, a compound Rel-like gene in the antibacterial defense of Drosophila.

Abstract: NF-kappa B/Rel transcription factors are central regulators of mammalian immunity and are also implicated in the induction of cecropins and other antibacterial peptides in insects. We identified the gene for Relish, a compound Drosophila protein that, like mammalian p105 and p100, contains both a Rel homology domain and an I kappa B-like domain. Relish is strongly induced in infected flies, and it can activate transcription from the Cecropin A1 promoter. A Relish transcript is also detected in early embryos, suggesting that it acts in both immunity and embryogenesis. The presence of a compound Rel protein in Drosophila indicates that similar proteins were likely present in primordial immune systems and may serve unique signaling functions.

Interleukin (IL)-6 gene expression in the central nervous system is necessary for fever response to lipopolysaccharide or IL-1 beta: a study on IL-6-deficient mice.

Abstract: Interleukin (IL)-6, IL-1 beta, and tumor necrosis factor alpha (TNF-alpha) are considered to act as endogenous pyrogens. Because of the complex pattern of cross-inductions between these cytokines, the relative role of the central and peripheral production of these cytokines in eliciting the fever response has not yet been clarified. The purpose of this study was to determine the role of IL-6 in the fever response by making use of mice carrying a null mutation in the IL-6 gene. The intraperitoneal injections of lipopolysaccharide (LPS) (50 micrograms/kg) and recombinant murine (rm) IL-1 beta (10 micrograms/kg), respectively, failed to evoke fever response in IL-6-deficient mice, whereas the same doses of LPS and rmIL-1 beta caused fever response in wild-type mice. The fever response could be induced in the IL-6-deficient mice by intracerebroventricular injection of recombinant human (rh) IL-6 (500 ng/mouse), whereas intracerebroventricular injection of rmIL-1 beta (100 ng/mouse) failed to produce fever response in the IL-6-deficient mice. These results suggest that central IL-6 is a necessary component of the fever response to both endogenous (IL-1 beta) and exogenous (LPS) pyrogens in mice and that IL-6 acts downstream from both peripheral and central IL-1 beta.

Price Level Targeting vs. Inflation Targeting: A Free Lunch?

Abstract: Price level targeting (without base drift) and inflation targeting (with base drift) are compared under commitment and discretion, with persistence in unemployment. Price level targeting is often said to imply more short-run inflation variability and thereby more employment variability than inflation targeting. Counter to this conventional wisdom, under discretion a price level target results in lower inflation variability than an inflation target (if unemployment is at least moderately persistent). A price level target also eliminates the inflation bias under discretion and, as is well known, reduces long-term price variability. Society may be better off assigning a price level target to the central bank even if its preferences correspond to inflation targeting. A price level target thus appears to have more advantages than commonly acknowledged.

Relationship marketing and imaginary organizations: a synthesis

Abstract: Explores the dependency between relationship marketing (RM) and new developments in organization theory. In RM, relationships, networks and interaction are in focus. The primary role of marketing is to connect suppliers and customers but RM also includes relationships with other stakeholders, both inside and outside the organization. Presents a theoretical discourse based on two recent developments in Nordic research. One is RM and its emergence from traditional marketing, services marketing, the network approach of industrial marketing, and quality management. The other is research concerning imaginary organizations, in which the organization consists of a network of relationships between suppliers, customers, subcontractors, competitors, authorities and others, rather than being a structure with clear boundaries. The synthesis of RM and imaginary organizations leads to the concept of complete marketing equilibrium, where not only the market but also the organization and society are included in a network of interactive relationships.

Performance of the DELPHI detector

Abstract: DELPHI (DEtector with Lepton, Photon and Hadron Identification) is a detector for e^+e^- physics, designed to provide high granularity over a 4\pi solid angle, allowing an effective particle identification. It has been operating at the LEP (Large Electron-Positron) collider at CERN since 1989. This article reviews its performance.

Value creation by company‐consumer interaction

Abstract: Company‐customer interaction is becoming increasingly widespread in industrial markets, bringing benefits that are both productive and strategic. This paper looks at the prerequisites for applying the same logic in consumer markets. The conclusion is that due to new technology and the emergence of more qualified and demanding consumers, the logic is already appearing in a wider range of industries, with interaction in one or more activities in the value‐creating process; in design, production and marketing as well as in the consumption and later destruction of products. But, up to now, the benefits are mainly on the consumer side. There seems to be some potential for considerable strategic advantages for companies, however, provided that their organizational structure is modified, new communication channels are built, the competence of the front‐line staff is developed, and the company culture becomes more consumer‐oriented.

Impaired Predator Evasion in Fat Blackcaps (Sylvia atricapilla)

Abstract: When birds are attacked by predators, take-off ability is crucial for the chance of survival. Recently, theoretical studies have predicted that predation risk in terms of reduced flight performance increases with body mass. However, empirical data are scarce. Because migratory birds sometimes double their body mass, mass dependent predation risk may be especially important during migratory fattening. Here we present the first study of take-off ability in relation to migratory fat load. Alarmed take-off flights of caged blackcaps (Sylvia atricapilla) induced by a simulated predator attack were analysed in terms of velocity and angle of ascent. Fat loads (percentage of fat-free body mass) of the birds ranged from 1% to 59%. An increase in fat load was found to influence both velocity and angle of ascent. From our results we calculated that blackcaps carrying 60% fat loads would have 32% lower angle of ascent and 17% lower velocity than blackcaps carrying no fat load. Even though the effect of fat load on the blackcaps was less than indicated in previous experimental studies of other species, our results suggest that the large fat loads needed for migration probably place them at increased risk of predation.

Concentration Effects in Aqueous NaCl Solutions. A Molecular Dynamics Simulation

Abstract: A series of constant-temperature/constant-pressure molecular dynamics simulations of aqueous NaCl solutions at different salt concentrations is carried out to investigate the structure and the dynamical properties. The simulations were performed with the number of molecules ranging from 256 to 2000. The simulations cover several nanoseconds to ensure the convergence of the results and to enable a proper determination of ion−ion radial distribution functions. The flexible SPC water model is used as the solvent, while the ions are treated as charged Lennard-Jones particles. Only a weak influence of the salt concentration is found on the ion−ion pair correlation functions. The structures of the hydrated shells around ion pairs are studied using three-body correlation functions. The self-diffusion and interdiffusion coefficients are found to decrease with an increase of salt concentration. Molar conductivities are calculated at different salt concentrations. The residence times of water molecules in the hydra...

Tree-ring variables as proxy-climate indicators: Problems with low-frequency signals

Abstract: In recent years there has been a notable increase in the number of research projects engaged in building supra-long (multi-millennial) tree-ring chronologies. Together with a growing awareness of the potential for anthropogenic climate change, this work is shifting the focus of dendroclimatology. Instead of a more traditional interpretation of tree-ring data in terms of annual-to-decadal timescale climate variability the emphasis is increasingly placed on century timescale changes. We review a number of problems with the interpretation of low-frequency climate change in tree-ring derived data. Perhaps the most significant is the high-pass filtering effect of “standardization” techniques commonly used in chronology construction to remove age-related sample bias in the original tree growth measurement data. These techniques effectively remove low-frequency variability and with it the evidence of long-term climate change. Other forcings may also be ‘corrupting’ the climate signal in the recent period (that used for calibrating the climate signal). Differences in the origin of the samples or changes in site ecology may also impart an inhomogeneity in the response of tree growth through time, hence violating the fundamental assumption of uniformitarianism that underpins proxy climate research.