Showing papers by "University of Zurich published in 2008"

The CMS experiment at the CERN LHC

Abstract: The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 10(34)cm(-2)s(-1) (10(27)cm(-2)s(-1)). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4 pi solid angle. Forward sampling calorimeters extend the pseudo-rapidity coverage to high values (vertical bar eta vertical bar <= 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.

Antiretroviral Treatment of Adult HIV Infection: 2012 Recommendations of the International Antiviral Society–USA Panel

Abstract: Context New trial data and drug regimens that have become available in the last 2 years warrant an update to guidelines for antiretroviral therapy (ART) in human immunodeficiency virus (HIV)–infected adults in resource-rich settings. Objective To provide current recommendations for the treatment of adult HIV infection with ART and use of laboratory-monitoring tools. Guidelines include when to start therapy and with what drugs, monitoring for response and toxic effects, special considerations in therapy, and managing antiretroviral failure. Data Sources, Study Selection, and Data Extraction Data that had been published or presented in abstract form at scientific conferences in the past 2 years were systematically searched and reviewed by an International Antiviral Society–USA panel. The panel reviewed available evidence and formed recommendations by full panel consensus. Data Synthesis Treatment is recommended for all adults with HIV infection; the strength of the recommendation and the quality of the evidence increase with decreasing CD4 cell count and the presence of certain concurrent conditions. Recommended initial regimens include 2 nucleoside reverse transcriptase inhibitors (tenofovir/emtricitabine or abacavir/lamivudine) plus a nonnucleoside reverse transcriptase inhibitor (efavirenz), a ritonavir-boosted protease inhibitor (atazanavir or darunavir), or an integrase strand transfer inhibitor (raltegravir). Alternatives in each class are recommended for patients with or at risk of certain concurrent conditions. CD4 cell count and HIV-1 RNA level should be monitored, as should engagement in care, ART adherence, HIV drug resistance, and quality-of-care indicators. Reasons for regimen switching include virologic, immunologic, or clinical failure and drug toxicity or intolerance. Confirmed treatment failure should be addressed promptly and multiple factors considered. Conclusion New recommendations for HIV patient care include offering ART to all patients regardless of CD4 cell count, changes in therapeutic options, and modifications in the timing and choice of ART in the setting of opportunistic illnesses such as cryptococcal disease and tuberculosis.

The LHCb detector at the LHC

Abstract: The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.

The Sixth Data Release of the Sloan Digital Sky Survey

Abstract: This paper describes the Sixth Data Release of the Sloan Digital Sky Survey. With this data release, the imaging of the northern Galactic cap is now complete. The survey contains images and parameters of roughly 287 million objects over 9583 deg(2), including scans over a large range of Galactic latitudes and longitudes. The survey also includes 1.27 million spectra of stars, galaxies, quasars, and blank sky ( for sky subtraction) selected over 7425 deg2. This release includes much more stellar spectroscopy than was available in previous data releases and also includes detailed estimates of stellar temperatures, gravities, and metallicities. The results of improved photometric calibration are now available, with uncertainties of roughly 1% in g, r, i, and z, and 2% in u, substantially better than the uncertainties in previous data releases. The spectra in this data release have improved wavelength and flux calibration, especially in the extreme blue and extreme red, leading to the qualitatively better determination of stellar types and radial velocities. The spectrophotometric fluxes are now tied to point-spread function magnitudes of stars rather than fiber magnitudes. This gives more robust results in the presence of seeing variations, but also implies a change in the spectrophotometric scale, which is now brighter by roughly 0.35 mag. Systematic errors in the velocity dispersions of galaxies have been fixed, and the results of two independent codes for determining spectral classifications and red-shifts are made available. Additional spectral outputs are made available, including calibrated spectra from individual 15 minute exposures and the sky spectrum subtracted from each exposure. We also quantify a recently recognized underestimation of the brightnesses of galaxies of large angular extent due to poor sky subtraction; the bias can exceed 0.2 mag for galaxies brighter than r = 14 mag.

Inflammatory and coagulation biomarkers and mortality in patients with HIV infection.

Abstract: Background In the Strategies for Management of Anti-Retroviral Therapy trial, all-cause mortality was higher for participants randomized to intermittent, CD4-guided antiretroviral treatment (ART) (drug conservation [DC]) than continuous ART (viral suppression [VS]). We hypothesized that increased HIV-RNA levels following ART interruption induced activation of tissue factor pathways, thrombosis, and fibrinolysis.

The genome of the model beetle and pest Tribolium castaneum.

Abstract: Tribolium castaneum is a member of the most species-rich eukaryotic order, a powerful model organism for the study of generalized insect development, and an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved the ability to interact with a diverse chemical environment, as shown by large expansions in odorant and gustatory receptors, as well as P450 and other detoxification enzymes. Development in Tribolium is more representative of other insects than is Drosophila, a fact reflected in gene content and function. For example, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, some being expressed in the growth zone crucial for axial elongation in short-germ development. Systemic RNA interference in T. castaneum functions differently from that in Caenorhabditis elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.

Egalitarianism in young children

Abstract: Human social interaction is strongly shaped by other-regarding preferences, that is, a concern for the welfare of others. These preferences are important for a unique aspect of human sociality-large scale cooperation with genetic strangers-but little is known about their developmental roots. Here we show that young children's other-regarding preferences assume a particular form, inequality aversion that develops strongly between the ages of 3 and 8. At age 3-4, the overwhelming majority of children behave selfishly, whereas most children at age 7-8 prefer resource allocations that remove advantageous or disadvantageous inequality. Moreover, inequality aversion is strongly shaped by parochialism, a preference for favouring the members of one's own social group. These results indicate that human egalitarianism and parochialism have deep developmental roots, and the simultaneous emergence of altruistic sharing and parochialism during childhood is intriguing in view of recent evolutionary theories which predict that the same evolutionary process jointly drives both human altruism and parochialism.

Electric field control of the LaAlO3/SrTiO3 interface ground state.

Abstract: Interfaces between complex oxides are emerging as one of the most interesting systems in condensed matter physics. In this special setting, in which translational symmetry is artificially broken, a variety of new and unusual electronic phases can be promoted. Theoretical studies predict complex phase diagrams and suggest the key role of the charge carrier density in determining the systems' ground states. A particularly fascinating system is the conducting interface between the band insulators LaAlO(3) and SrTiO(3) (ref. 3). Recently two possible ground states have been experimentally identified: a magnetic state and a two-dimensional superconducting condensate. Here we use the electric field effect to explore the phase diagram of the system. The electrostatic tuning of the carrier density allows an on/off switching of superconductivity and drives a quantum phase transition between a two-dimensional superconducting state and an insulating state. Analyses of the magnetotransport properties in the insulating state are consistent with weak localization and do not provide evidence for magnetism. The electric field control of superconductivity demonstrated here opens the way to the development of new mesoscopic superconducting circuits.

Concise review: isolation and characterization of cells from human term placenta: outcome of the first international Workshop on Placenta Derived Stem Cells.

Abstract: Placental tissue draws great interest as a source of cells for regenerative medicine because of the phenotypic plasticity of many of the cell types isolated from this tissue. Furthermore, placenta, which is involved in maintaining fetal tolerance, contains cells that display immunomodulatory properties. These two features could prove useful for future cell therapy-based clinical applications. Placental tissue is readily available and easily procured without invasive procedures, and its use does not elicit ethical debate. Numerous reports describing stem cells from different parts of the placenta, using nearly as numerous isolation and characterization procedures, have been published. Considering the complexity of the placenta, an urgent need exists to define, as clearly as possible, the region of origin and methods of isolation of cells derived from this tissue. On March 23-24, 2007, the first international Workshop on Placenta Derived Stem Cells was held in Brescia, Italy. Most of the research published in this area focuses on mesenchymal stromal cells isolated from various parts of the placenta or epithelial cells isolated from amniotic membrane. The aim of this review is to summarize and provide the state of the art of research in this field, addressing aspects such as cell isolation protocols and characteristics of these cells, as well as providing preliminary indications of the possibilities for use of these cells in future clinical applications.

Clumps and streams in the local dark matter distribution

Abstract: The standard cosmological model includes the presumption that cold dark matter plays a major part in large-scale mass distribution in the Universe from the Big Bang to the present. Though successful in explaining large-scale events, until now simulations of galaxy formation using the cold dark matter model have failed to resolve certain smaller-scale structures. Now Diemand et al. have simulated the assembly of the dark matter 'halo' of the Milky Way at much better resolution than has been possible previously. The model then produces thousands of clumps surviving within the inner halo, some of them in the vicinity of the Solar System. In cold dark matter cosmological models, structures form and grow by merging of smaller units, previous simulations have shown that such merging is incomplete as the inner cores of halos survive and orbit as 'subhalos' within their hosts. This paper reports a simulation that resolves such substructure in the very inner regions of the Galactic halo. Hundreds of very concentrated dark matter clumps survive near the solar circle, as well as numerous cold streams. In cold dark matter cosmological models1,2, structures form and grow through the merging of smaller units3. Numerical simulations have shown that such merging is incomplete; the inner cores of haloes survive and orbit as ‘subhaloes’ within their hosts4,5. Here we report a simulation that resolves such substructure even in the very inner regions of the Galactic halo. We find hundreds of very concentrated dark matter clumps surviving near the solar circle, as well as numerous cold streams. The simulation also reveals the fractal nature of dark matter clustering: isolated haloes and subhaloes contain the same relative amount of substructure and both have cusped inner density profiles. The inner mass and phase-space densities of subhaloes match those of recently discovered faint, dark-matter-dominated dwarf satellite galaxies6,7,8, and the overall amount of substructure can explain the anomalous flux ratios seen in strong gravitational lenses9,10. Subhaloes boost γ-ray production from dark matter annihilation by factors of 4 to 15 relative to smooth galactic models. Local cosmic ray production is also enhanced, typically by a factor of 1.4 but by a factor of more than 10 in one per cent of locations lying sufficiently close to a large subhalo. (These estimates assume that the gravitational effects of baryons on dark matter substructure are small.)

The role of exercise and PGC1α in inflammation and chronic disease

Abstract: Inadequate physical activity is linked to many chronic diseases. But the mechanisms that tie muscle activity to health are unclear. The transcriptional coactivator PGC1alpha has recently been shown to regulate several exercise-associated aspects of muscle function. We propose that this protein controls muscle plasticity, suppresses a broad inflammatory response and mediates the beneficial effects of exercise.

A systematic review of the 5-year survival and complication rates of implant-supported single crowns

Abstract: OBJECTIVES: The objective of this systematic review was to assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological and technical complications. METHODS: An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on SCs with a mean follow-up time of at least 5 years. Failure and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5-year proportions. RESULTS: Twenty-six studies from an initial yield of 3601 titles were finally selected and data were extracted. In a meta-analysis of these studies, survival of implants supporting SCs was 96.8% [95% confidence interval (CI): 95.9-97.6%] after 5 years. The survival rate of SCs supported by implants was 94.5% (95% CI: 92.5-95.9%) after 5 years of function. The survival rate of metal-ceramic crowns, 95.4% (95% CI: 93.6-96.7%), was significantly (P=0.005) higher than the survival rate, 91.2% (95% CI: 86.8-94.2%), of all-ceramic crowns. Peri-implantitis and soft tissue complications occurred adjacent to 9.7% of the SCs and 6.3% of the implants had bone loss exceeding 2 mm over the 5-year observation period. The cumulative incidence of implant fractures after 5 years was 0.14%. After 5 years, the cumulative incidence of screw or abutment loosening was 12.7% and 0.35% for screw or abutment fracture. For supra-structure-related complications, the cumulative incidence of ceramic or veneer fractures was 4.5%. CONCLUSION: It can be concluded that after an observation period of 5 years, high survival rates for implants and implant-supported SCs can be expected. However, biological and particularly technical complications are frequent.

Catapult-like release of mitochondrial DNA by eosinophils contributes to antibacterial defense

Abstract: Although eosinophils are considered useful in defense mechanisms against parasites, their exact function in innate immunity remains unclear. The aim of this study is to better understand the role of eosinophils within the gastrointestinal immune system. We show here that lipopolysaccharide from Gram-negative bacteria activates interleukin-5 (IL-5)- or interferon-gamma-primed eosinophils to release mitochondrial DNA in a reactive oxygen species-dependent manner, but independent of eosinophil death. Notably, the process of DNA release occurs rapidly in a catapult-like manner--in less than one second. In the extracellular space, the mitochondrial DNA and the granule proteins form extracellular structures able to bind and kill bacteria both in vitro and under inflammatory conditions in vivo. Moreover, after cecal ligation and puncture, Il5-transgenic but not wild-type mice show intestinal eosinophil infiltration and extracellular DNA deposition in association with protection against microbial sepsis. These data suggest a previously undescribed mechanism of eosinophil-mediated innate immune responses that might be crucial for maintaining the intestinal barrier function after inflammation-associated epithelial cell damage, preventing the host from uncontrolled invasion of bacteria.

Altered expression of MicroRNA in synovial fibroblasts and synovial tissue in rheumatoid arthritis.

Abstract: Objective MicroRNAs (miRNA) have recently emerged as a new class of modulators of gene expression. In this study we investigated the expression, regulation, and function of miR-155 and miR-146a in rheumatoid arthritis (RA) synovial fibroblasts (RASFs) and RA synovial tissue. Methods Locked nucleic acid microarray was used to screen for differentially expressed miRNA in RASFs treated with tumor necrosis factor α (TNFα). TaqMan-based real-time polymerase chain reaction was applied to measure the levels of miR-155 and miR-146a. Enforced overexpression of miR-155 was used to investigate the function of miR-155 in RASFs. Results Microarray analysis of miRNA expressed in RASFs treated with TNFα revealed a prominent up-regulation of miR-155. Constitutive expression of both miR-155 and miR-146a was higher in RASFs than in those from patients with osteoarthritis (OA), and expression of miR-155 could be further induced by TNFα, interleukin-1β, lipopolysaccharide, poly(I-C), and bacterial lipoprotein. The expression of miR-155 in RA synovial tissue was higher than in OA synovial tissue. Enforced expression of miR-155 in RASFs was found to repress the levels of matrix metalloproteinase 3 (MMP-3) and reduce the induction of MMPs 3 and 1 by Toll-like receptor ligands and cytokines. Moreover, compared with monocytes from RA peripheral blood, RA synovial fluid monocytes displayed higher levels of miR-155. Conclusion This study provides the first description of increased expression of miRNA miR-155 and miR-146a in RA. Based on these findings, we postulate that the inflammatory milieu may alter miRNA expression profiles in resident cells of the rheumatoid joints. Considering the repressive effect of miR-155 on the expression of MMPs 3 and 1 in RASFs, we hypothesize that miR-155 may be involved in modulation of the destructive properties of RASFs.

Fission-fusion dynamics: new research frameworks

Abstract: Renewed interest in fission‐fusion dynamics is due to the recognition that such dynamics may create unique challenges for social interaction and distinctive selective pressures acting on underlying communicative and cognitive abilities. New frameworks for integrating current knowledge on fission‐fusion dynamics emerge from a fundamental rethinking of the term “fission‐fusion” away from its current general use as a label for a particular modal type of social system (i.e., “fission‐fusion societies”). Specifically, because the degree of spatial and temporal cohesion of group members varies both within and across taxa, any social system can be described in terms of the extent to which it expresses fission‐fusion dynamics. This perspective has implications for socioecology, communication, cognitive demands, and human social evolution.

The Content Analysis of Media Frames: Toward Improving Reliability and Validity

Abstract: The main purpose of this study was to shed light on methodological problems in the content analysis of media frames After a review of 5 common methods, we will present an alternative procedure that aims at improving reliability and validity Based on the definition of frames advanced by R M Entman (1993), we propose that previously defined frame elements systematically group together in a specific way This pattern of frame elements can be identified across several texts by means of cluster analysis The proposed method is demonstrated with data on the coverage of the issue of biotechnology in The New York Times It is concluded that the proposed method yields better results in terms of reliability and validity compared to previous methods

Stress that Doesn't Pay: The Commuting Paradox*

Abstract: People spend a lot of time commuting and often find it a burden. According to standard economics, the burden of commuting is chosen when compensated either on the labor or on the housing market so that individuals’ utility is equalized. However, in a direct test of this strong notion of equilibrium with panel data, we find that people with longer commuting time report systematically lower subjective well-being. This result is robust with regard to a number of alternative explanations. We mention several possibilities of an extended model of human behavior able to explain this “commuting paradox”.

Being Independent is a Great Thing: Subjective Evaluations of Self-Employment and Hierarchy

Abstract: One can be independent, or one can be subject to decisions made by others. This paper argues that this difference, embodied in the institutional distinction between the decision-making procedures ‘market’ and ‘hierarchy’, affects individual wellbeing beyond outcomes. Taking self-employment as an important case of independence, it is shown that the self-employed derive higher satisfaction from work than those employed in organizations, irrespective of income gained or hours worked. This is evidence for procedural utility: people value not only outcomes, but also the processes leading to outcomes.

Hexastore: sextuple indexing for semantic web data management

Abstract: Despite the intense interest towards realizing the Semantic Web vision, most existing RDF data management schemes are constrained in terms of efficiency and scalability Still, the growing popularity of the RDF format arguably calls for an effort to offset these drawbacks Viewed from a relational-database perspective, these constraints are derived from the very nature of the RDF data model, which is based on a triple format Recent research has attempted to address these constraints using a vertical-partitioning approach, in which separate two-column tables are constructed for each property However, as we show, this approach suffers from similar scalability drawbacks on queries that are not bound by RDF property value In this paper, we propose an RDF storage scheme that uses the triple nature of RDF as an asset This scheme enhances the vertical partitioning idea and takes it to its logical conclusion RDF data is indexed in six possible ways, one for each possible ordering of the three RDF elements Each instance of an RDF element is associated with two vectors; each such vector gathers elements of one of the other types, along with lists of the third-type resources attached to each vector element Hence, a sextuple-indexing scheme emerges This format allows for quick and scalable general-purpose query processing; it confers significant advantages (up to five orders of magnitude) compared to previous approaches for RDF data management, at the price of a worst-case five-fold increase in index space We experimentally document the advantages of our approach on real-world and synthetic data sets with practical queries

Use of uterine artery Doppler ultrasonography to predict pre-eclampsia and intrauterine growth restriction: a systematic review and bivariable meta-analysis

Abstract: Background: Alterations in waveforms in the uterine artery are associated with the development of pre-eclampsia and intrauterine growth restriction. We investigated the predictive accuracy of all uterine artery Doppler indices for both conditions in the first and second trimesters. Methods: We identified relevant studies through searches of MEDLINE, EMBASE, the Cochrane Library and Medion databases (all records to April 2006) and by checking bibliographies of identified studies and consulting with experts. Four of us independently selected studies, extracted data and assessed study validity. We performed a bivariable meta-analysis of sensitivity and specificity and calculated likelihood ratios. Results: We identified 74 studies of pre-eclampsia (total 79 547 patients) and 61 studies of intrauterine growth restriction (total 41 131 patients). Uterine artery Doppler ultrasonography provided a more accurate prediction when performed in the second trimester than in the first-trimester. Most Doppler indices had poor predictive characteristics, but this varied with patient risk and outcome severity. An increased pulsatility index with notching was the best predictor of pre-eclampsia (positive likelihood ratio 21.0 among high-risk patients and 7.5 among low-risk patients). It was also the best predictor of overall (positive likelihood ratio 9.1) and severe (positive likelihood ratio 14.6) intrauterine growth restriction among low-risk patients. Interpretation: Abnormal uterine artery waveforms are a better predictor of pre-eclampsia than of intrauterine growth restriction. A pulsatility index, alone or combined with notching, is the most predictive Doppler index. These indices should be used in clinical practice. Future research should also concentrate on combining uterine artery Doppler ultrasonography with other tests.

X-ray structure of a prokaryotic pentameric ligand-gated ion channel

Abstract: Pentameric ligand-gated ion channels (pLGICs) are key players in the early events of electrical signal transduction at chemical synapses. The family codes for a structurally conserved scaffold of channel proteins that open in response to the binding of neurotransmitter molecules. All proteins share a pentameric organization of identical or related subunits that consist of an extracellular ligand-binding domain followed by a transmembrane channel domain. The nicotinic acetylcholine receptor (nAChR) is the most thoroughly studied member of the pLGIC family (for recent reviews see refs 1-3). Two sources of structural information provided an architectural framework for the family. The structure of the soluble acetylcholine-binding protein (AChBP) defined the organization of the extracellular domain and revealed the chemical basis of ligand interaction. Electron microscopy studies of the nAChR from Torpedo electric ray have yielded a picture of the full-length protein and have recently led to the interpretation of an electron density map at 4.0 A resolution. Despite the wealth of experimental information, high-resolution structures of any family member have so far not been available. Until recently, the pLGICs were believed to be only expressed in multicellular eukaryotic organisms. The abundance of prokaryotic genome sequences, however, allowed the identification of several homologous proteins in bacterial sources. Here we present the X-ray structure of a prokaryotic pLGIC from the bacterium Erwinia chrysanthemi (ELIC) at 3.3 A resolution. Our study reveals the first structure of a pLGIC at high resolution and provides an important model system for the investigation of the general mechanisms of ion permeation and gating within the family.

Geographical and taxonomic biases in invasion ecology

Abstract: Invasive alien species come from most taxonomic groups, and invasion biology is searching for robust cross-taxon generalizations and principles. An analysis of 2670 papers dealing with 892 invasive species showed that all major groups of invaders are well studied, but that most information on the mechanisms of invasion has emerged from work on a limited number of the most harmful invaders. A strong geographical bias, with Africa and Asia understudied, inhibits a balanced understanding of invasion, because we might be lacking knowledge of specific invasion mechanisms from poorly studied, regionally specific habitats. International cooperation is required to achieve a more geographically balanced picture of biological invasions. Invasive species with the greatest impact are best studied, but more studies of species that are naturalized but not (yet) invasive are needed to improve understanding of the mechanisms acting during the naturalization phase of invasions and leading to successful invasion.

West European Politics in the Age of Globalization

Abstract: Over the past three decades the effects of globalization and denationalization have created a division between ‘winners’ and ‘losers’ in Western Europe. This study examines the transformation of party political systems in six countries (Austria, France, Germany, the Netherlands, Switzerland and the UK) using opinion surveys, as well as newly collected data on election campaigns. The authors argue that, as a result of structural transformations and the strategic repositioning of political parties, Europe has observed the emergence of a tripolar configuration of political power, comprising the left, the moderate right, and the new populist right. They suggest that, through an emphasis on cultural issues such as mass immigration and resistance to European integration, the traditional focus of political debate - the economy - has been downplayed or reinterpreted in terms of this new political cleavage. This new analysis of Western European politics will interest all students of European politics and political sociology.

Prevalence, course, and comorbidity of insomnia and depression in young adults.

Abstract: EPIDEMIOLOGIC STUDIES SHOW THAT 20% TO 35% OF THE GENERAL POPULATION REPORT INSOMNIA SYMPTOMS, AND THAT 10% TO 20% HAVE A CLINICALLY significant insomnia syndrome.1–5 Fewer data are available to address 2 other important questions regarding the epidemiology of insomnia: its natural history and its relationship with psychiatric disorders. Several studies have indicated that insomnia is often a chronic condition,6–8 but many of these studies have used retrospective designs or prospective designs with limited duration or limited number of follow-up evaluations. Results of other studies9,10 have suggested that, at least for older adults, incidence and remission rates for narrowly defined insomnia are about equal. Thus, uncertainty exists regarding the course and chronicity of insomnia. The 2005 National Institutes of Health State of the Science Conference Statement on the Manifestations and Management of Chronic Insomnia in Adults identified studies addressing this issue as an important direction for insomnia-related research: “Longitudinal observational studies are needed to identify factors affecting incidence of, natural history of, and remission from chronic insomnia.11” A number of risk factors for chronic insomnia have been identified, including medical problems, female sex, and increasing age.4,5,12–16 However, depression and depressive symptoms are the largest and most consistent risk factors for insomnia.7,17 Conversely, insomnia is a frequent symptom of depression, and it is often hypothesized to be an antecedent or risk factor. To date, however, relatively few studies have examined prospective longitudinal data from representative community samples to define the relationship between insomnia and depression; these studies were recently reviewed.18 Data from the Epidemiologic Catchment Area Study showed that insomnia was associated with an increased risk of depression if it was present at 2 interviews over a 1-year follow-up interval but not if it was present only at the initial interview.3 Weissman and colleagues4 examined Epidemiologic Catchment Area data and found that insomnia not comorbid with a psychiatric disorder was associated with a significantly increased risk of developing first-episode major depression, alcohol abuse, and panic disorder within a 1-year follow-up period. Other studies have found similar relationships between insomnia and depression among older adults19 and younger adults 20 with 2- to 3-year follow-up intervals, even after controlling for prior depressive symptoms. Finally, Chang et al21 reported a prospective study of 1053 male medical students with annual follow-up questionnaires over a mean of 34 years. Insomnia and difficulty sleeping under stress predicted depression, as assessed by questionnaires and the general health questionnaire. In contrast with these studies, but consistent with the results of Ford and Kamerow, were the earlier findings of the Zurich Study,22 comprising a 2- to 7-year follow-up of young adults. Although we found strong cross-sectional associations between insomnia and depression, we did not find that insomnia predicted future depression. Although a considerable amount of data suggests an association between insomnia and subsequent depression, previous studies have been limited by the representativeness of their samples, the duration and frequency of follow-up, or the definition of insomnia. The current analyses from the Zurich Study include a representative population sample, a follow-up interval of 21 years, and the ability to examine different patterns of insomnia, including a conservative case definition based on Diagnostic and Statistical Manual (DSM)-IV criteria for primary insomnia. The aims of these analyses were (1) to describe the prevalence and prospective course of insomnia in a representative young adult sample and (2) to describe the cross-sectional and longitudinal associations between insomnia and depression, including the question of whether insomnia predicts depression or vice versa.

How relevant is recalcitrance for the stabilization of organic matter in soils

Abstract: Traditionally, the selective preservation of certain recalcitrant organic compounds and the formation of recalcitrant humic substances have been regarded as an important mechanism for soil organic matter (SOM) stabilization. Based on a critical overview of available methods and on results from a cooperative research program, this paper evaluates how relevant recalcitrance is for the long-term stabilization of SOM or its fractions. Methodologically, recalcitrance is difficult to assess, since the persistence of certain SOM fractions or specific compounds may also be caused by other stabilization mechanisms, such as physical protection or chemical interactions with mineral surfaces. If only free particulate SOM obtained from density fractionation is considered, it rarely reaches ages exceeding 50 y. Older light particles have often been identified as charred plant residues or as fossil C. The degradability of the readily bioavailable dissolved or water-extractable OM fraction is often negatively correlated with its content in aromatic compounds, which therefore has been associated with recalcitrance. But in subsoils, dissolved organic matter aromaticity and biodegradability both are very low, indicating that other factors or compounds limit its degradation. Among the investigated specific compounds, lignin, lipids, and their derivatives have mean turnover times faster or similar as that of bulk SOM. Only a small fraction of the lignin inputs seems to persist in soils and is mainly found in the fine textural size fraction ( 40–50 y, unless fossil C was present in substantial amounts, as at a site exposed to lignite inputs in the past. Here, turnover of pyrolysis products seemed to be much longer, even for those attributed to carbohydrates or proteins. Apparently, fossil C from lignite coal is also utilized by soil organisms, which is further evidenced by low 14C concentrations in microbial phospholipid fatty acids from this site. Also, black C from charred plant materials was susceptible to microbial degradation in a short-term (60 d) and a long-term (2 y) incubation experiment. This degradation was enhanced, when glucose was supplied as an easily available microbial substrate. Similarly, SOM mineralization in many soils generally increased after addition of carbohydrates, amino acids, or simple organic acids, thus indicating that stability may also be caused by substrate limitations. It is concluded that the presented results do not provide much evidence that the selective preservation of recalcitrant primary biogenic compounds is a major SOM-stabilization mechanism. Old SOM fractions with slow turnover rates were generally only found in association with soil minerals. The only not mineral-associated SOM components that may be persistent in soils appear to be black and fossil C.

Robustness and evolvability: a paradox resolved.

Abstract: Understanding the relationship between robustness and evolvability is key to understand how living things can withstand mutations, while producing ample variation that leads to evolutionary innovations. Mutational robustness and evolvability, a system's ability to produce heritable variation, harbour a paradoxical tension. On one hand, high robustness implies low production of heritable phenotypic variation. On the other hand, both experimental and computational analyses of neutral networks indicate that robustness enhances evolvability. I here resolve this tension using RNA genotypes and their secondary structure phenotypes as a study system. To resolve the tension, one must distinguish between robustness of a genotype and a phenotype. I confirm that genotype (sequence) robustness and evolvability share an antagonistic relationship. In stark contrast, phenotype (structure) robustness promotes structure evolvability. A consequence is that finite populations of sequences with a robust phenotype can access large amounts of phenotypic variation while spreading through a neutral network. Population-level processes and phenotypes rather than individual sequences are key to understand the relationship between robustness and evolvability. My observations may apply to other genetic systems where many connected genotypes produce the same phenotypes.