Showing papers by "University of Fribourg published in 2006"

Priming: Getting Ready for Battle

Abstract: Infection of plants by necrotizing pathogens or colonization of plant roots with certain beneficial microbes causes the induction of a unique physiological state called "priming." The primed state can also be induced by treatment of plants with various natural and synthetic compounds. Primed plants display either faster, stronger, or both activation of the various cellular defense responses that are induced following attack by either pathogens or insects or in response to abiotic stress. Although the phenomenon has been known for decades, most progress in our understanding of priming has been made over the past few years. Here, we summarize the current knowledge of priming in various induced-resistance phenomena in plants.

Rhythmic CLOCK-BMAL1 binding to multiple E-box motifs drives circadian Dbp transcription and chromatin transitions.

Abstract: Mammalian circadian rhythms are based on transcriptional and post-translational feedback loops. Essentially, the activity of the transcription factors BMAL1 (also known as MOP3) and CLOCK is rhythmically counterbalanced by Period (PER) and Cryptochrome (CRY) proteins to govern time of day-dependent gene expression. Here we show that circadian regulation of the mouse albumin D element-binding protein (Dbp) gene involves rhythmic binding of BMAL1 and CLOCK and marked daily chromatin transitions. Thus, the Dbp transcription cycle is paralleled by binding of BMAL1 and CLOCK to multiple extra- and intragenic E boxes, acetylation of Lys9 of histone H3, trimethylation of Lys4 of histone H3 and a reduction of histone density. In contrast, the antiphasic daily repression cycle is accompanied by dimethylation of Lys9 of histone H3, the binding of heterochromatin protein 1alpha and an increase in histone density. The rhythmic conversion of transcriptionally permissive chromatin to facultative heterochromatin relies on the presence of functional BMAL1-CLOCK binding sites.

Correlation between thermodynamical stabilities of metal borohydrides and cation electronegativites: First-principles calculations and experiments

Abstract: Note: Times Cited: 251 Reference EPFL-ARTICLE-206012doi:10.1103/PhysRevB.74.045126View record in Web of Science URL: ://WOS:000239426800043 Record created on 2015-03-03, modified on 2017-05-12

Critical role for the p110α phosphoinositide-3-OH kinase in growth and metabolic regulation

Abstract: The eight catalytic subunits of the mammalian phosphoinositide-3-OH kinase (PI(3)K) family form the backbone of an evolutionarily conserved signalling pathway; however, the roles of most PI(3)K isoforms in organismal physiology and disease are unknown. To delineate the role of p110alpha, a ubiquitously expressed PI(3)K involved in tyrosine kinase and Ras signalling, here we generated mice carrying a knockin mutation (D933A) that abrogates p110alpha kinase activity. Homozygosity for this kinase-dead p110alpha led to embryonic lethality. Mice heterozygous for this mutation were viable and fertile, but displayed severely blunted signalling via insulin-receptor substrate (IRS) proteins, key mediators of insulin, insulin-like growth factor-1 and leptin action. Defective responsiveness to these hormones led to reduced somatic growth, hyperinsulinaemia, glucose intolerance, hyperphagia and increased adiposity in mice heterozygous for the D933A mutation. This signalling function of p110alpha derives from its highly selective recruitment and activation to IRS signalling complexes compared to p110beta, the other broadly expressed PI(3)K isoform, which did not contribute to IRS-associated PI(3)K activity. p110alpha was the principal IRS-associated PI(3)K in cancer cell lines. These findings demonstrate a critical role for p110alpha in growth factor and metabolic signalling and also suggest an explanation for selective mutation or overexpression of p110alpha in a variety of cancers.

Predicting Homework Effort: Support for a Domain-Specific, Multilevel Homework Model.

Abstract: According to the domain-specific, multilevel homework model proposed in the present study, students' homework effort is influenced by expectancy and value beliefs, homework characteristics, parental homework behavior, and conscientiousness. The authors used structural equation modeling and hierarchical linear modeling analyses to test the model in 2 studies with 414 and 1,501 8th graders, respectively. In line with the authors' assumptions, most intercorrelations observed between corresponding homework variables across 2 school subjects were small to moderate, conscientiousness and homework motivation proved to be strong predictors of homework effort, and perceived homework quality varied considerably between classes and predicted homework motivation and behavior. Findings highlight the need to take into account the domain specificity and multilevel character of homework variables when analyzing students' homework behavior.

Identification of PAD2 as a γ‐glutamylcysteine synthetase highlights the importance of glutathione in disease resistance of Arabidopsis

Abstract: *† ‡ Summary The Arabidopsis pad2-1 mutant belongs to a series of non-allelic camalexin-deficient mutants. It was originally described as showing enhanced susceptibility to virulent strains of Pseudomonas syringae and was later shown to be hyper-susceptible to the oomycete pathogen Phytophthora brassicae (formerly P. porri). Surprisingly, in both pathosystems, the disease susceptibility of pad2-1 was not caused by the camalexin deficiency, suggesting additional roles of PAD2 in disease resistance. The susceptibility of pad2-1 to P. brassicae was used to map the mutation to the gene At4g23100, which encodes c-glutamylcysteine synthetase (c-ECS, GSH1). GSH1 catalyzes the first committed step of glutathione (GSH) biosynthesis. The pad2-1 mutation caused an S to N transition at amino acid position 298 close to the active center. The conclusion that PAD2 encodes GSH1 is supported by several lines of evidence: (i) pad2-1 mutants contained only about 22% of wild-type amounts of GSH, (ii) genetic complementation of pad2-1 with wild-type GSH1 cDNA restored GSH production, accumulation of camalexin in response to P. syringae and resistance to P. brassicae and P. syringae, (iii) another GSH1 mutant, cad2-1, showed pad2-like phenotypes, and (iv) feeding of GSH to excised leaves of pad2-1 restored camalexin production and resistance to P. brassicae. Inoculation of Col-0 with P. brassicae caused a coordinated increase in the transcript abundance of GSH1 and GSH2, the gene encoding the second enzyme in GSH biosynthesis, and resulted in enhanced foliar GSH accumulation. The pad2-1 mutant showed enhanced susceptibility to additional pathogens, suggesting an important general role of GSH in disease resistance of Arabidopsis.

Nogo-A-specific antibody treatment enhances sprouting and functional recovery after cervical lesion in adult primates.

Abstract: In rodents, after spinal lesion, neutralizing the neurite growth inhibitor Nogo-A promotes axonal sprouting and functional recovery. To evaluate this treatment in primates, 12 monkeys were subjected to cervical lesion. Recovery of manual dexterity and sprouting of corticospinal axons were enhanced in monkeys treated with Nogo-A-specific antibody as compared to monkeys treated with control antibody.

Mountain weather and climate : A general overview and a focus on climatic change in the Alps

Abstract: Meteorological and climatic processes in mountain regions play a key role in many environmental systems, in particular the quantity and quality of water that influences both aquatic ecosystems and economic systems often far beyond the boundaries of the mountains themselves. This paper will provide a general overview of some of the particular characteristics of mountain weather and climate, to highlight some of the unique atmospheric features that are associated with regions of complex topography. The second part of the paper will focus upon characteristics of climate and climatic change in the European Alps, a region with a wealth of high quality data that allows an assessment on how climate and dependent environmental systems have evolved in the course of the 20th century and how alpine climate may undergo further changes to “global warming” in the 21st century, as the atmosphere responds to increasing levels of greenhouse gases that are expected in coming decades.

Cutting edge: The phosphoinositide 3-kinase p110 delta is critical for the function of CD4(+)CD25(+)Foxp3(+) regulatory T cells

Abstract: CD4+CD25+Foxp3+ regulatory T cells (Tregs) contribute to the maintenance of peripheral tolerance by inhibiting the expansion and function of conventional T cells. Treg development and homeostasis are regulated by the Ag receptor, costimulatory receptors such as CD28 and CTLA-4, and cytokines such as IL-2, IL-10, and TGF-beta. Here we show that the proportions of Tregs in the spleen and lymph nodes of mice with inactive p110delta PI3K (p110deltaD910A/D910A) are reduced despite enhanced Treg selection in the thymus. p110deltaD910A/D910A CD4+CD25+Foxp3+ Tregs showed attenuated suppressor function in vitro and failed to secrete IL-10. In adoptive transfer experiments, p110deltaD910A/D910A T cells failed to protect against experimental colitis. The identification of p110delta as an intracellular signaling protein that regulates the activity of CD4+CD25+Foxp3+ Tregs may facilitate the further elucidation of the molecular mechanisms responsible for Treg-mediated suppression.

The Relationship Between Dyadic Coping and Marital Quality: A 2-Year Longitudinal Study

Abstract: Previous studies have revealed that the ways couples deal with stress in their lives are significantly associated with their marital quality and overall marital functioning. However, there has been little empirical evidence linking dyadic coping with marital quality over time. This study addresses the relationship between dyadic coping and marital quality among 90 couples over a period of 2 years. The results reveal that dyadic coping was significantly associated with marital quality over 2 years. For women, both their own dyadic coping and that of their partner were significant predictors, whereas for men only their own dyadic coping was predictive. The results are discussed with regard to prevention of marital distress.

Gene expression: long-term gene silencing by RNAi.

Abstract: Small RNA molecules participate in a variety of activities in the cell: in a process known as RNA interference (RNAi), double-stranded RNA triggers the degradation of messenger RNA that has a matching sequence; the small RNA intermediates of this process can also modify gene expression in the nucleus Here we show that a single episode of RNAi in the nematode Caenorhabditis elegans can induce transcriptional silencing effects that are inherited indefinitely in the absence of the original trigger Our findings may prove useful in the ongoing development of RNAi to treat disease

The Epidermis-Specific Extracellular BODYGUARD Controls Cuticle Development and Morphogenesis in Arabidopsis

Abstract: The outermost epidermal cell wall is specialized to withstand pathogens and natural stresses, and lipid-based cuticular polymers are the major barrier against incursions. The Arabidopsis thaliana mutant bodyguard (bdg), which exhibits defects characteristic of the loss of cuticle structure not attributable to a lack of typical cutin monomers, unexpectedly accumulates significantly more cell wall‐bound lipids and epicuticular waxes than wild-type plants. Pleiotropic effects of the bdg mutation on growth, viability, and cell differentiation are also observed. BDG encodes a member of the a/b-hydrolase fold protein superfamilyandisexpressedexclusivelyinepidermalcells.UsingStrep-tagepitope-taggedBDGformutantcomplementation and immunolocalization, we show that BDG is a polarly localized protein that accumulates in the outermost cell wall in the epidermis.Withregardtotheappearance andstructureofthecuticle, thephenotype conferredbybdgisreminiscent ofthatof transgenic Arabidopsis plants that express an extracellular fungal cutinase, suggesting that bdg may be incapable of completing the polymerization of carboxylic esters in the cuticular layer of the cell wall or the cuticle proper. We propose that BDGcodesforanextracellularsynthaseresponsiblefortheformationofcuticle.ThealternativehypothesisproposesthatBDG controls the proliferation/differentiation status of the epidermis via an unknown mechanism.

Climate risks and their impact on agriculture and forests in Switzerland

Abstract: There is growing evidence that, as a result of global climate change, some of the most severe weather events could become more frequent in Europe over the next 50 to 100 years. The paper aims to (i) describe observed trends and scenarios for summer heat waves, windstorms and heavy precipitation, based on results from simulations with global circulation models, regional climate models, and other downscaling procedures, and (ii) discuss potential impacts on agricultural systems and forests in Switzerland. Trends and scenarios project more frequent heavy precipitation during winter corresponding, for example, to a three-fold increase in the exceedance of today's 15-year extreme values by the end of the 21st century. This increases the risk of large-scale flooding and loss of topsoil due to erosion. In contrast, constraints in agricultural practice due to waterlogged soils may become less in a warmer climate. In summer, the most remarkable trend is a decrease in the frequency of wet days, and shorter return times of heat waves and droughts. This increases the risk of losses of crop yield and forage quality. In forests, the more frequent occurrence of dry years may accelerate the replacement of sensitive tree species and reduce carbon stocks, and the projected slight increase in the frequency of extreme storms by the end of the century could increase the risk of windthrow. Some possible measures to maintain goods and services of agricultural and forest ecosystems are mentioned, but it is suggested that more frequent extremes may have more severe consequences than progressive changes in means. In order to effectively decrease the risk for social and economic impacts, long-term adaptive strategies in agriculture and silviculture, investments for prevention, and new insurance concepts seem necessary.

Experimental studies on intermediate compound of LiBH4

Abstract: The formation condition of an intermediate compound of LiBH4 during the partial dehydriding reaction and its local atomistic structure have been experimentally investigated. LiBH4 changes into an intermediate compound accompanying the release of approximately 11mass% of hydrogen at 700–730K. The Raman spectra indicate that the B–H bending and stretching modes of the compound appear at lower and higher frequencies, respectively, as compared to those of LiBH4. These features are consistent with the theoretical calculation on the monoclinic Li2B12H12, consisting of Li+ and [B12H12]2− ions, as a possible intermediate compound of LiBH4.

The thrifty 'catch-up fat' phenotype: its impact on insulin sensitivity during growth trajectories to obesity and metabolic syndrome

Abstract: The analyses of large epidemiological databases have suggested that infants and children who show catch-up growth, or adiposity rebound at a younger age, are predisposed to the development of obesity, type 2 diabetes and cardiovascular diseases later in life. The pathophysiological mechanisms by which these growth trajectories confer increased risks for these diseases are obscure, but there is compelling evidence that the dynamic process of catch-up growth per se, which often overlaps with adiposity rebound at a younger age, is characterized by hyperinsulinemia and by a disproportionately higher rate in the recovery of body fat than lean tissue (i.e. preferential 'catch-up fat'). This paper first focuses upon the almost ubiquitous nature of this preferential 'catch-up fat' phenotype across the life cycle as a risk factor for obesity and insulin-related complications - not only in infants and children who experienced catch-up growth after earlier fetal or neonatal growth retardation, or after preterm birth, but also in adults who show weight recovery after substantial weight loss owing to famine, disease-cachexia or periodic dieting. It subsequently reviews the evidence indicating that such preferential catch-up fat is primarily driven by energy conservation (thrifty) mechanisms operating via suppressed thermogenesis, with glucose thus spared from oxidation in skeletal muscle being directed towards de novo lipogenesis and storage in white adipose tissue. A molecular-physiological framework is presented which integrates emerging insights into the mechanisms by which this thrifty 'catch-up fat' phenotype crosslinks with early development of insulin and leptin resistance. In the complex interactions between genetic constitution of the individual, programming earlier in life, and a subsequent lifestyle of energy dense foods and low physical activity, this thrifty 'catch-up fat' phenotype--which probably evolved to increase survival capacity in a hunter-gatherer lifestyle of periodic food shortages--is a central event in growth trajectories to obesity and to diseases that cluster into the insulin resistance (metabolic) syndrome.

Recent Advances in Understanding Endothelial Dysfunction in Atherosclerosis

Abstract: Over the last two decades, it has become evident that decreased bioavailability of endothelial nitric oxide (NO) produced from endothelial NO synthase (eNOS), referred to as endothelial dysfunction, plays a crucial role in the development and progression of atherosclerosis. Much progress has been made in understanding the mechanisms of decreased endothelial NO bioavailability at the levels of regulation of eNOS gene expression, eNOS enzymatic activity and NO inactivation. Initial studies suggest that increasing eNOS gene expression would improve endothelial NO release in the hope of inhibiting the progression of atherosclerosis. Recent experimental studies, however, do not always support this therapeutic concept and show some evidence that overexpression of eNOS in atherosclerosis may be even harmful for the disease progression.Thus, recent research to improve endothelial function in atherosclerosis has focused on regulation of eNOS enzymatic activity and prevention of NO inactivation by oxidative stress. Since the role of oxidative stress in endothelial NO bioavailability has been reviewed in a large number of comprehensive articles, this article focuses on the relevant regulatory mechanisms of eNOS enzymatic activity that are emerging to play a role in endothelial dysfunction in atherosclerosis.

Challenges in Managing Nonprofit Organizations: A Research Overview

Abstract: The topic of "management" and nonprofit organizations (NPOs) continues to fascinate scholars. This paper draws on varying theoretical perspectives to explore their respective contributions to our knowledge of NPOs. The two longstanding and contrasting disciplines of economics and sociology have contributed most, traditionally, to the study of NPOs. However, neither of these disciplines has resolved all the dilemmas associated with NPOs. The standard economic model does not apply well to the distinctive non-market situation of NPOs. The sociological perspectives offer interesting insight, but fail to develop plans of action for NPOs. However, both of these traditional perspectives are starting to be eclipsed by the focus on marketing research.

First-principles study on the stability of intermediate compounds of LiBH(4)

Abstract: Note: Times Cited: 110 Reference EPFL-ARTICLE-206017doi:10.1103/PhysRevB.74.075110View record in Web of Science URL: ://WOS:000240238800042 Record created on 2015-03-03, modified on 2017-05-12

Impact of fungal drug transporters on fungicide sensitivity, multidrug resistance and virulence

Abstract: Drug transporters are membrane proteins that provide protection for organisms against natural toxic products and fungicides. In plant pathogens, drug transporters function in baseline sensitivity to fungicides, multidrug resistance (MDR) and virulence on host plants. This paper describes drug transporters of the filamentous fungi Aspergillus nidulans (Eidam) Winter, Botrytis cinerea Pers and Mycosphaerella graminicola (Fuckel) Schroter that function in fungicide sensitivity and resistance. The fungi possess ATP-binding cassette (ABC) drug transporters that mediate MDR to fungicides in laboratory mutants. Similar mutants are not pronounced in field resistance to most classes of fungicide but may play a role in resistance to azoles. MDR may also explain historical cases of resistance to aromatic hydrocarbon fungicides and dodine. In clinical situations, MDR development in Candida albicans (Robin) Berkhout mediated by ABC transporters in patients suffering from candidiasis is common after prolonged treatment with azoles. Factors that can explain this striking difference between agricultural and clinical situations are discussed. Attention is also paid to the risk of MDR development in plant pathogens in the future. Finally, the paper describes the impact of fungal drug transporters on drug discovery.

Thermodynamical stability of calcium borohydride Ca(BH4)(2)

Abstract: We have prepared pure $\mathrm{Ca}{(\mathrm{B}{\mathrm{H}}_{4})}_{2}$ without any solvent adducts and determined its structural parameters by powder x-ray diffraction measurement. The crystal structure of $\mathrm{Ca}{(\mathrm{B}{\mathrm{H}}_{4})}_{2}$ is found to be orthorhombic with space group $Fddd$ (No. 70). Using this structural information, the first-principles calculations have been performed to investigate the fundamental properties of $\mathrm{Ca}{(\mathrm{B}{\mathrm{H}}_{4})}_{2}$. The interaction between Ca atoms and $\mathrm{B}{\mathrm{H}}_{4}$ complexes has an ionic character while the internal bonding of $\mathrm{B}{\mathrm{H}}_{4}$ is essentially covalent. It is confirmed that $\mathrm{Ca}{(\mathrm{B}{\mathrm{H}}_{4})}_{2}$ obeys the linear relationship between the heat of formation and the Pauling electronegativity of the cation, which has been proposed in a previous study [Nakamori et al., Phys. Rev. B 74, 045126 (2006)].

Detecting local adaptation in widespread grassland species – the importance of scale and local plant community

Abstract: 1 Adaptation of plant populations to local environments has been shown in many species but local adaptation is not always apparent and spatial scales of differentiation are not well known. In a reciprocal transplant experiment we tested whether: (i) three widespread grassland species are locally adapted at a European scale; (ii) detection of local adaptation depends on competition with the local plant community; and (iii) local differentiation between neighbouring populations from contrasting habitats can be stronger than differentiation at a European scale. 2 Seeds of Holcus lanatus, Lotus corniculatus and Plantago lanceolata from a Swiss, Czech and UK population were sown in a reciprocal transplant experiment at fields that exhibit environmental conditions similar to the source sites. Seedling emergence, survival, growth and reproduction were recorded for two consecutive years. 3 The effect of competition was tested by comparing individuals in weeded monocultures with plants sown together with species from the local grassland community. To compare large-scale vs. small-scale differentiation, a neighbouring population from a contrasting habitat (wet-dry contrast) was compared with the 'home' and 'foreign' populations. 4 In P. lanceolata and H. lanatus, a significant home-site advantage was detected in fitness-related traits, thus indicating local adaptation. In L. corniculatus, an overall superiority of one provenance was found. 5 The detection of local adaptation depended on competition with the local plant community. In the absence of competition the home-site advantage was underestimated in P. lanceolata and overestimated in H. lanatus. 6 A significant population differentiation between contrasting local habitats was found. In some traits, this small-scale was greater than large-scale differentiation between countries. 7 Our results indicate that local adaptation in real plant communities cannot necessarily be predicted from plants grown in weeded monocultures and that tests on the relationship between fitness and geographical distance have to account for habitat-dependent small-scale differentiation. Considering the strong small-scale differentiation, a local provenance from a different habitat may not be the best choice in ecological restoration if distant populations from a more similar habitat are available.

Empirical support for optimal virulence in a castrating parasite.

Abstract: The trade-off hypothesis for the evolution of virulence predicts that parasite transmission stage production and host exploitation are balanced such that lifetime transmission success (LTS) is maximised. However, the experimental evidence for this prediction is weak, mainly because LTS, which indicates parasite fitness, has been difficult to measure. For castrating parasites, this simple model has been modified to take into account that parasites convert host reproductive resources into transmission stages. Parasites that kill the host too early will hardly benefit from these resources, while postponing the killing of the host results in diminished returns. As predicted from optimality models, a parasite inducing castration should therefore castrate early, but show intermediate levels of virulence, where virulence is measured as time to host killing. We studied virulence in an experimental system where a bacterial parasite castrates its host and produces spores that are not released until after host death. This permits estimating the LTS of the parasite, which can then be related to its virulence. We exposed replicate individual Daphnia magna (Crustacea) of one host clone to the same amount of bacterial spores and followed individuals until their death. We found that the parasite shows strong variation in the time to kill its host and that transmission stage production peaks at an intermediate level of virulence. A further experiment tested for the genetic basis of variation in virulence by comparing survival curves of daphniids infected with parasite spores obtained from early killing versus late killing infections. Hosts infected with early killer spores had a significantly higher death rate as compared to those infected with late killers, indicating that variation in time to death was at least in part caused by genetic differences among parasites. We speculate that the clear peak in lifetime reproductive success at intermediate killing times may be caused by the exceptionally strong physiological trade-off between host and parasite reproduction. This is the first experimental study to demonstrate that the production of propagules is highest at intermediate levels of virulence and that parasite genetic variability is available to drive the evolution of virulence in this system.

Sgk kinases and their role in epithelial transport

Abstract: ▪ Abstract The serum/glucocorticoid-induced kinase Sgk1 plays an important role in the regulation of epithelial ion transport. This kinase is very rapidly regulated at the transcriptional level as well as via posttranslational modifications involving phosphorylation by the MAP or PI-3 kinase pathways and/or ubiquitylation. Although Sgk1 is a cell survival kinase, its primary role likely concerns the regulation of epithelial ion transport, as suggested by the phenotype of Sgk1-null mice, which display a defect in Na+ homeostasis owing to disturbed renal tubular Na+ handling. In this review we first discuss the molecular, cellular, and regulatory aspects of Sgk1 and its paralogs. We then discuss its roles in the physiology and pathophysiology of epithelial ion transport.

GUP1 of Saccharomyces cerevisiae encodes an O-acyltransferase involved in remodeling of the GPI anchor.

Abstract: The anchors of mature glycosylphosphatidylinositol (GPI)-anchored proteins of Saccharomyces cerevisiae contain either ceramide or diacylglycerol with a C26:0 fatty acid in the sn2 position. The primary GPI lipid added to newly synthesized proteins in the ER consists of diacylglycerol with conventional C16 and C18 fatty acids. Here we show that GUP1 is essential for the synthesis of the C26:0-containing diacylglycerol anchors. Gup1p is an ER membrane protein with multiple membrane-spanning domains harboring a motif that is characteristic of membrane-bound O-acyl-transferases (MBOAT). Gup1Δ cells make normal amounts of GPI proteins but most mature GPI anchors contain lyso-phosphatidylinositol, and others possess phosphatidylinositol with conventional C16 and C18 fatty acids. The incorporation of the normal ceramides into the anchors is also disturbed. As a consequence, the ER-to-Golgi transport of the GPI protein Gas1p is slow, and mature Gas1p is lost from the plasma membrane into the medium. Gup1Δ cells have fragile cell walls and a defect in bipolar bud site selection. GUP1 function depends on the active site histidine of the MBOAT motif. GUP1 is highly conserved among fungi and protozoa and the gup1Δ phenotype is partially corrected by GUP1 homologues of Aspergillus fumigatus and Trypanosoma cruzi.

Stress and Coping Among Stable-Satisfied, Stable-Distressed and Separated/Divorced Swiss Couples

Abstract: This article presents a 5-year prospective longitudinal study exploring the effects of stress and individual and dyadic coping on relationship stability among couples in Switzerland. Stress and coping variables assessed at the beginning of the study (tl) were used as predictors for the relationship status five years later (i.e., stable-satisfied; stable-distressed; separated/divorced). At the time of first measurement, all three groups differed significantly in their stress and individual and dyadic coping profiles. On average, the stable-satisfied couples were characterized by a lower level of stress, practiced less dysfunctional individual coping strategies, and relied more frequently on interpersonal (dyadic) coping when dealing with stress. At the end of the five-year period, it was possible to classify couples with 62.1% accuracy into one of three groups-stable-satisfied, stable-distressed, or separated/divorced. On the basis of the predictor variables, 73.3% of the couples could be correctl...

Cyclostratigraphy - concepts, definitions, and applications

Abstract: Cyclostratigraphy is the subdiscipline of stratigraphy that deals with the identification, characterization, correlation, and interpretation of cyclic variations in the stratigraphic record and, in particular, with their application in geochronology by improving the accuracy and resolution of time-stratigraphic frameworks. As such it uses astronomical cycles of known periodicities to date and interpret the sedimentary record. The most important of these cycles are the Earth’s orbital cycles of precession, obliquity, and eccentricity (Milankovitch cycles), which result from perturbations of the Earth’s orbit and its rotational axis. They have periods ranging from 20 to 400 kyr, and even up to millions of years. These cycles translate (via orbital-induced changes in insolation) into climatic, oceanographic, sedimentary, and biological changes that are potentially recorded in the sedimentary archives through geologic time. Many case studies have demonstrated that detailed analysis of the sedimentary record (stacking patterns of beds, disconformities, facies changes, fluctuations in biological composition, and/or changes in geochemical composition) enables identification of these cycles with high confidence. Once the relationship between the sedimentary record and the orbital forcing is established, an unprecedented high time resolution becomes available, providing a precise and accurate framework for the timing of Earth system processes. For the younger part of the geologic past, astronomical time scales have been constructed by tuning cyclic palaeoclimatic records to orbital and insolation target curves; these time scales are directly tied to the Present. In addition, the astronomical tuning has been used to calibrate the 40Ar/39Ar dating method. In the older geologic past, “floating” astronomical time scales provide a high time resolution for stratigraphic intervals, even if their radiometric age is subject to the error margins of the dating techniques. Because the term “sedimentary cycle” is used in many different ways by the geologic community and does not always imply time significance, we propose using “astrocycle” once the cycle periodicity has been demonstrated by a thorough cyclostratigraphic analysis. Authors’ addresses: André Strasser, Department of Geosciences, University of Fribourg, CH-1700 Fribourg, Switzerland, e-mail: andreas.strasser@unifr.ch; Frederik J. Hilgen, Faculty of Earth Sciences, University of Utrecht, 3584 CD Utrecht, The Netherlands, e-mail: fhilgen@geo.uu.nl; Philip H. Heckel, Department of Geoscience, University of Iowa, Iowa City, Iowa 52242, U.S.A., e-mail: philip-heckel@uiowa.edu DOI: 10.1127/0078-0421/2006/0042-0075 0078-00421/06/0042-0075 $ 10.00 © 2007 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart

A high-sensitivity laser-pumped Mx magnetometer

Abstract: We discuss the design and performance of a laser-pumped cesium vapor magnetometer in the Mx configuration. The device will be employed in the control and stabilization of fluctuating magnetic fields and gradients in a new experiment searching for a permanent electric dipole moment of the neutron. We have determined the intrinsic sensitivity of the device to be 15 fT in a 1 Hz bandwidth, limited by technical laser noise. In the shot noise limit the magnetometer can reach a sensitivity of 10 fT in a 1 Hz bandwidth. We have used the device to study the fluctuations of a stable magnetic field in a multi-layer magnetic shield for integration times in the range of 2–100 seconds. The residual fluctuations for times up to a few minutes are traced back to the instability of the power supply used to generate the field.