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Showing papers by "University of Konstanz published in 2008"


Journal ArticleDOI
02 Oct 2008-Nature
TL;DR: This work shows how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions, and demonstrates the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations.
Abstract: Magnetic resonance imaging and optical microscopy are key technologies in the life sciences. For microbiological studies, especially of the inner workings of single cells, optical microscopy is normally used because it easily achieves resolution close to the optical wavelength. But in conventional microscopy, diffraction limits the resolution to about half the wavelength. Recently, it was shown that this limit can be partly overcome by nonlinear imaging techniques, but there is still a barrier to reaching the molecular scale. In contrast, in magnetic resonance imaging the spatial resolution is not determined by diffraction; rather, it is limited by magnetic field sensitivity, and so can in principle go well below the optical wavelength. The sensitivity of magnetic resonance imaging has recently been improved enough to image single cells, and magnetic resonance force microscopy has succeeded in detecting single electrons and small nuclear spin ensembles. However, this technique currently requires cryogenic temperatures, which limit most potential biological applications. Alternatively, single-electron spin states can be detected optically, even at room temperature in some systems. Here we show how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions. By placing these nitrogen-vacancy spins in functionalized diamond nanocrystals, biologically specific magnetofluorescent spin markers can be produced. Significantly, we show that this nanometre-scale resolution can be achieved without any probes located closer than typical cell dimensions. Furthermore, we demonstrate the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations. The potential impact of single-spin imaging at room temperature is far-reaching. It could lead to the capability to probe biologically relevant spins in living cells.

1,814 citations


Journal ArticleDOI
13 Nov 2008-Nature
TL;DR: Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms, and documents the presence of hundreds of genes from bacteria, likely to provide novel possibilities for metabolite management and for perception of environmental signals.
Abstract: Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one- fifth of the primary productivity on Earth(1,2). The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology(3-5). Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes (similar to 40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans.

1,500 citations


Journal ArticleDOI
TL;DR: The conjectured hardness of maximizing modularity both in the general case and with the restriction to cuts is proved and an Integer Linear Programming formulation is given.
Abstract: Modularity is a recently introduced quality measure for graph clusterings. It has immediately received considerable attention in several disciplines, particularly in the complex systems literature, although its properties are not well understood. We study the problem of finding clusterings with maximum modularity, thus providing theoretical foundations for past and present work based on this measure. More precisely, we prove the conjectured hardness of maximizing modularity both in the general case and with the restriction to cuts and give an Integer Linear Programming formulation. This is complemented by first insights into the behavior and performance of the commonly applied greedy agglomerative approach.

1,201 citations


Book ChapterDOI
TL;DR: The possibilities to collect and store data increase at a faster rate than the ability to use it for making decisions, and in most applications, raw data has no value in itself; instead the authors want to extract the information contained in it.
Abstract: We are living in a world which faces a rapidly increasing amount of data to be dealt with on a daily basis. In the last decade, the steady improvement of data storage devices and means to create and collect data along the way influenced our way of dealing with information: Most of the time, data is stored without filtering and refinement for later use. Virtually every branch of industry or business, and any political or personal activity nowadays generate vast amounts of data. Making matters worse, the possibilities to collect and store data increase at a faster rate than our ability to use it for making decisions. However, in most applications, raw data has no value in itself; instead we want to extract the information contained in it.

1,047 citations


Book ChapterDOI
01 Jan 2008
TL;DR: The Konstanz Information Miner as mentioned in this paper is a modular environment that enables easy visual assembly and interactive execution of a data pipeline, which is designed as a teaching, research and collaboration platform.
Abstract: The Konstanz Information Miner is a modular environment, which enables easy visual assembly and interactive execution of a data pipeline. It is designed as a teaching, research and collaboration platform, which enables simple integration of new algorithms and tools as well as data manipulation or visualization methods in the form of new modules or nodes. In this paper we describe some of the design aspects of the underlying architecture and briefly sketch how new nodes can be incorporated.

1,024 citations


Journal ArticleDOI
TL;DR: In this paper, a number of variants are reviewed, placed into context, and shown to be computable with simple variants of the algorithm commonly used for the standard case.

820 citations


Journal ArticleDOI
01 Dec 2008
TL;DR: The results show that augmenting photographs with already available 3D models of the world supports a wide variety of new ways for us to experience and interact with the authors' everyday snapshots.
Abstract: In this paper, we introduce a novel system for browsing, enhancing, and manipulating casual outdoor photographs by combining them with already existing georeferenced digital terrain and urban models. A simple interactive registration process is used to align a photograph with such a model. Once the photograph and the model have been registered, an abundance of information, such as depth, texture, and GIS data, becomes immediately available to our system. This information, in turn, enables a variety of operations, ranging from dehazing and relighting the photograph, to novel view synthesis, and overlaying with geographic information. We describe the implementation of a number of these applications and discuss possible extensions. Our results show that augmenting photographs with already available 3D models of the world supports a wide variety of new ways for us to experience and interact with our everyday snapshots.

745 citations


Journal ArticleDOI
TL;DR: This study adds to research on job-stress recovery and affect regulation by showing which specific experiences from the nonwork domain may improve affect before the start of the next working day.
Abstract: In this study, the authors used a within-person design to examine the relation between recovery experiences (psychological detachment, relaxation, mastery experiences) during leisure time, sleep, and affect in the next morning. Daily survey data gathered over the course of 1 work week from 166 public administration employees analyzed with a hierarchical linear modeling approach showed that low psychological detachment from work during the evening predicted negative activation and fatigue, whereas mastery experiences during the evening predicted positive activation and relaxation predicted serenity. Sleep quality showed relations with all affective states variables. This study adds to research on job-stress recovery and affect regulation by showing which specific experiences from the nonwork domain may improve affect before the start of the next working day.

625 citations


Journal ArticleDOI
01 May 2008-Kyklos
TL;DR: This article provided a measure of equality of educational opportunity in 54 countries, estimated as the effect of family background on student performance in two international TIMSS tests, and showed how organizational features of the education system affect equality.
Abstract: We provide a measure of equality of educational opportunity in 54 countries, estimated as the effect of family background on student performance in two international TIMSS tests. We then show how organizational features of the education system affect equality of educational opportunity. Our model predicts that late tracking and a long pre-school cycle are beneficial for equality, while pre-school enrollment is detrimental at low levels of enrollment and beneficial at higher levels. Using cross-country variations in education policies and their interaction with family background at the student level, we provide empirical evidence supportive of these predictions.

570 citations


Journal ArticleDOI
TL;DR: Results from a study of 33 research and development teams confirmed that transformational leadership works through support for innovation, which in turn interacts with climate for excellence such that support for innovations enhances team innovation only when climate for Excellence is high.
Abstract: Fostering team innovation is increasingly an important leadership function. However, the empirical evidence for the role of transformational leadership in engendering team innovation is scarce and mixed. To address this issue, the authors link transformational leadership theory to principles of M. A. West's (1990) team climate theory and propose an integrated model for the relationship between transformational leadership and team innovation. This model involves support for innovation as a mediating process and climate for excellence as a moderator. Results from a study of 33 research and development teams confirmed that transformational leadership works through support for innovation, which in turn interacts with climate for excellence such that support for innovation enhances team innovation only when climate for excellence is high.

558 citations


Journal ArticleDOI
TL;DR: It is shown that the Mycobacterium tuberculosis complex consists of two independent clades, one composed exclusively of M. tuberculosis lineages from humans and the other composed of both animal and human isolates, supporting the hypothesis of an original human host.
Abstract: The evolutionary timing and spread of the Mycobacterium tuberculosis complex (MTBC), one of the most successful groups of bacterial pathogens, remains largely unknown. Here, using mycobacterial tandem repeat sequences as genetic markers, we show that the MTBC consists of two independent clades, one composed exclusively of M. tuberculosis lineages from humans and the other composed of both animal and human isolates. The latter also likely derived from a human pathogenic lineage, supporting the hypothesis of an original human host. Using Bayesian statistics and experimental data on the variability of the mycobacterial markers in infected patients, we estimated the age of the MTBC at 40,000 years, coinciding with the expansion of "modern" human populations out of Africa. Furthermore, coalescence analysis revealed a strong and recent demographic expansion in almost all M. tuberculosis lineages, which coincides with the human population explosion over the last two centuries. These findings thus unveil the dynamic dimension of the association between human host and pathogen populations.

Journal ArticleDOI
TL;DR: Phase-locked terahertz transients with peak electric fields of 108 MV/cm and center frequencies continuously tunable from 10 to 72 THz are generated via difference-frequency mixing of two parametrically amplified pulse trains from a single white-light seed.
Abstract: Phase-locked terahertz transients with peak electric fields of 108 MV/cm and center frequencies continuously tunable from 10 to 72 THz are generated via difference-frequency mixing of two parametrically amplified pulse trains from a single white-light seed. Free space electro-optic sampling with 8 fs gating pulses from a two-branch Er:fiber laser allows us to monitor all transients directly in the time domain. We identify extreme terahertz nonlinearities in the detector crystal with subcycle resolution.

Journal ArticleDOI
TL;DR: The findings show that an electron spin in the graphene layer can be manipulated in a controlled way and have important implications for graphene-based spintronic devices.
Abstract: We report on angle-resolved photoemission studies of the electronic $\ensuremath{\pi}$ states of high-quality epitaxial graphene layers on a Ni(111) surface. In this system the electron binding energy of the $\ensuremath{\pi}$ states shows a strong dependence on the magnetization reversal of the Ni film. The observed extraordinarily large energy shift up to 225 meV of the graphene-derived $\ensuremath{\pi}$ band peak position for opposite magnetization directions is attributed to a manifestation of the Rashba interaction between spin-polarized electrons in the $\ensuremath{\pi}$ band and the large effective electric field at the graphene/Ni interface. Our findings show that an electron spin in the graphene layer can be manipulated in a controlled way and have important implications for graphene-based spintronic devices.

Journal ArticleDOI
09 Jan 2008-PLOS ONE
TL;DR: A detailed synthesis of carbohydrate metabolism in diatoms based on the genome sequences of Thalassiosira pseudonana and Phaeodactylum tricornutum is presented, which provides novel insights into acquisition of dissolved inorganic carbon and primary metabolic pathways of carbon in two different diats, which is of significance for an improved understanding of global carbon cycles.
Abstract: Background Diatoms are unicellular algae responsible for approximately 20% of global carbon fixation. Their evolution by secondary endocytobiosis resulted in a complex cellular structure and metabolism compared to algae with primary plastids.

Journal ArticleDOI
TL;DR: Emotionally relevant adjectives are processed spontaneously and selectively and healthy subjects may have a natural bias toward pleasant information facilitating late ERPs to pleasant adjectives as well as their superior recall.
Abstract: We investigated to what extent emotional connotation influences cortical potentials during reading. To this end, event-related potentials (ERPs) were recorded during reading of high arousal pleasant and unpleasant and low arousal neutral adjectives that were presented at rates of 1 Hz and 3 Hz. Enhanced processing of both pleasant and unpleasant emotional compared to neutral adjectives was first reflected in an amplified early posterior negativity (EPN) starting from 200 ms after word onset. Later potentials (>300 ms), as analyzed in the slower 1 Hz condition, revealed facilitated processing selectively for pleasant adjectives that were associated with a reduced N400 and an enhanced late positive potential (LPP). Pleasant adjectives were also better remembered in an incidental memory test. Thus, emotionally relevant adjectives are processed spontaneously and selectively. Initially, emotional arousal drives attention capture (EPN). Healthy subjects may have a natural bias toward pleasant information facilitating late ERPs (N400, LPP) to pleasant adjectives as well as their superior recall.

Journal ArticleDOI
TL;DR: The availability of the first complete genome sequences for four model microorganisms capable of syntrophic metabolism provides the genetic framework to begin dissecting the biochemistry of the marginal energy economies and interspecies interactions that are characteristic of the syntrophic lifestyle.
Abstract: Syntrophic metabolism is diverse in two respects: phylogenetically with microorganisms capable of syntrophic metabolism found in the Deltaproteobacteria and in the low G+C gram-positive bacteria, and metabolically given the wide variety of compounds that can be syntrophically metabolized. The latter includes saturated fatty acids, unsaturated fatty acids, alcohols, and hydrocarbons. Besides residing in freshwater and marine anoxic sediments and soils, microbes capable of syntrophic metabolism also have been observed in more extreme habitats, including acidic soils, alkaline soils, thermal springs, and permanently cold soils, demonstrating that syntrophy is a widely distributed metabolic process in nature. Recent ecological and physiological studies show that syntrophy plays a far larger role in carbon cycling than was previously thought. The availability of the first complete genome sequences for four model microorganisms capable of syntrophic metabolism provides the genetic framework to begin dissecting the biochemistry of the marginal energy economies and interspecies interactions that are characteristic of the syntrophic lifestyle.

Journal ArticleDOI
TL;DR: Strictly manualized narrative exposure therapy was compared with more flexible trauma counseling and both active treatment groups were statistically and clinically superior to MG on PTSD symptoms and physical health but did not differ from each other.
Abstract: Traumatic stress due to conflict and war causes major mental health problems in many resource-poor countries. The objective of this study was to examine whether trained lay counselors can carry out effective treatment of posttraumatic stress disorder (PTSD) in a refugee settlement. In a randomized controlled dissemination trial in Uganda with 277 Rwandan and Somalian refugees who were diagnosed with PTSD the authors investigated the effectiveness of psychotherapy administered by lay counselors. Strictly manualized narrative exposure therapy (NET) was compared with more flexible trauma counseling (TC) and a no-treatment monitoring group (MG). Fewer participants (4%) dropped out of NET treatment than TC (21%). Both active treatment groups were statistically and clinically superior to MG on PTSD symptoms and physical health but did not differ from each other. At follow-up, a PTSD diagnosis could not be established anymore in 70% of NET and 65% TC participants, whereas only 37% in MG did not meet PTSD criteria anymore. Short-term psychotherapy carried out by lay counselors with limited training can be effective to treat war-related PTSD in a refugee settlement.

Journal ArticleDOI
TL;DR: Data argue for a relationship between war violence and violent behavior inflicted on children in their families and the recent Tsunami experience resulted as significant predictors of PTSD in children, thus highlighting the detrimental effect that the experience of cumulative stress can have on children's mental health.
Abstract: The consequences of war violence and natural disasters on the mental health of children as well as on family dynamics remain poorly understood. Aim of the present investigation was to establish the prevalence and predictors of traumatic stress related to war, family violence and the recent Tsunami experience in children living in a region affected by a long-lasting violent conflict. In addition, the study looked at whether higher levels of war violence would be related to higher levels of violence within the family and whether this would result in higher rates of psychological problems in the affected children. 296 Tamil school children in Sri Lanka's North-Eastern provinces were randomly selected for the survey. Diagnostic interviews were carried out by extensively trained local Master level counselors. PTSD symptoms were established by means of a validated Tamil version of the UCLA PTSD Index. Additionally, participants completed a detailed checklist of event types related to organized and family violence. 82.4% of the children had experienced at least one war-related event. 95.6% reported at least one aversive experience out of the family violence spectrum. The consequences are reflected in a 30.4% PTSD and a 19.6% Major Depression prevalence. Linear regression analyses showed that fathers' alcohol intake and previous exposure to war were significantly linked to the amount of maltreatment reported by the child. A clear dose-effect relationship between exposure to various stressful experiences and PTSD was found in the examined children. Data argue for a relationship between war violence and violent behavior inflicted on children in their families. Both of these factors, together with the experience of the recent Tsunami, resulted as significant predictors of PTSD in children, thus highlighting the detrimental effect that the experience of cumulative stress can have on children's mental health.

Journal ArticleDOI
TL;DR: Using x-ray absorption spectroscopy, it is shown that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS) and is the first to be described in a living system.
Abstract: Brown algae of the Laminariales (kelps) are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine and, in particular, the major source of iodocarbons in the coastal atmosphere. Nevertheless, the chemical state and biological significance of accumulated iodine have remained unknown to this date. Using x-ray absorption spectroscopy, we show that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS). We propose here that its biological role is that of an inorganic antioxidant, the first to be described in a living system. Upon oxidative stress, iodide is effluxed. On the thallus surface and in the apoplast, iodide detoxifies both aqueous oxidants and ozone, the latter resulting in the release of high levels of molecular iodine and the consequent formation of hygroscopic iodine oxides leading to particles, which are precursors to cloud condensation nuclei. In a complementary set of experiments using a heterologous system, iodide was found to effectively scavenge ROS in human blood cells.

Journal ArticleDOI
TL;DR: Goal shielding was supported by implementation intentions geared at controlling potentially interfering inner states and forming if-then plans enhanced the rate of goal attainment in two field experiments concerned with dieting and athletic goals.
Abstract: Forming an implementation intention or "if-then plan" promotes the attainment of different types of goals (Gollwitzer, 1999; Gollwitzer & Sheeran, 2006). So far, research on implementation intentions has focused on the initiation of goal striving, whereas the issue of shielding of ongoing goal striving has been largely neglected. In two field experiments concerned with dieting (Study 1) and athletic goals (Study 2), goal shielding was supported by implementation intentions geared at controlling potentially interfering inner states (i.e., cravings for junk food in Study 1, and disruptive thoughts, feelings, and physiological states in Study 2). In both experiments, forming if-then plans enhanced the rate of goal attainment. Thus, implementation intention formation can be used to promote the realization of desired outcomes not only by facilitating getting started with goal striving but also by preventing goal striving from straying off course.

Journal ArticleDOI
TL;DR: It is suggested that values affirmation reduces defensiveness via self-transcendence, rather than self-integrity (i.e., self-worth or self-images).
Abstract: Previous research has repeatedly shown that writing about an important value, compared with writing about an unimportant value, reduces defensiveness in response to self-threatening information, but has not identified why. Study 1 showed that participants who wrote about an important value reported more positive other-directed feelings, such as love and connection, than participants who wrote about an unimportant value. Study 2 replicated this effect, and showed that loving and connected feelings, but not positive or negative self-directed feelings, completely accounted for the effect of a values-affirmation manipulation on smokers' acceptance of information indicating that smoking harms health. These studies, in concert with previous research, suggest that values affirmation reduces defensiveness via self-transcendence, rather than self-integrity (i.e., self-worth or self-images).

Journal ArticleDOI
TL;DR: It is proposed that the redundancy in gene repertoires possessed by all vertebrates, including hagfishes and lampreys, was introduced primarily by genome duplications, which might serve generally to distinguish vertebrates from invertebrates at the genomic level.
Abstract: Two rounds of whole-genome duplications are thought to have played an important role in the establishment of gene repertoires in vertebrates. These events occurred during chordate evolution after the split of the urochordate and cephalochordate lineages but before the radiation of extant gnathostomes (jawed vertebrates). During this interval, diverse agnathans (jawless fishes), including cyclostomes (hagfishes and lampreys), diverged. However, there is no solid evidence for the timing of these genome duplications in relation to the divergence of cyclostomes from the gnathostome lineage. We conducted cDNA sequencing in diverse early vertebrates for members of homeobox-containing (Dlx and ParaHox) and other gene families that would serve as landmarks for genome duplications. Including these new sequences, we performed a molecular phylogenetic census using the maximum likelihood method for 55 gene families. In most of these gene families, we detected many more gene duplications before the cyclostome-gnathostome split, than after. Many of these gene families (e.g., visual opsins, RAR, Notch) have multiple paralogs in conserved, syntenic genomic regions that must have been generated by large-scale duplication events. Taken together, this indicates that the genome duplications occurred before the cyclostome-gnathostome split. We propose that the redundancy in gene repertoires possessed by all vertebrates, including hagfishes and lampreys, was introduced primarily by genome duplications. Apart from subsequent lineage-specific modifications, these ancient genome duplication events might serve generally to distinguish vertebrates from invertebrates at the genomic level.

Journal ArticleDOI
TL;DR: In this article, the authors found that both engagement when being at work and disengagement when being away from work are most beneficial for employees' affective states and that psychological detachment is particularly important when work engagement is high.
Abstract: Although earlier research has shown that work engagement is associated with positive outcomes for the employee and the organization, this paper suggests that employees also need time periods for temporarily disengaging (i.e., psychological detaching) from work. We hypothesized that work engagement and psychological detachment from work during off-job time predict high positive affect and low negative affect and that psychological detachment is particularly important when work engagement is high. Over the course of four working weeks, 159 employees from five German organizations from various industries completed surveys twice a week, at the beginning and the end of four consecutive working weeks. Hierarchical linear modelling showed that a person's general level of work engagement and the week-specific level of psychological detachment from work during off-job time jointly predicted affect at the end of the working week. As expected, work engagement moderated the relationship between psychological detachment and positive affect. These findings suggest that both engagement when being at work and disengagement when being away from work are most beneficial for employees' affective states.

Journal ArticleDOI
TL;DR: This work strongly proposes allelopathy as an important mechanism in the interaction between submerged macrophytes and phytoplankton in shallow lakes based on the frequent occurrence of active species and the knowledge of potential target species.

Journal ArticleDOI
TL;DR: Water-level fluctuations affect the ecological processes and patterns of lakes in several ways as discussed by the authors, such as losing or losing aquatic habitats and feeding or breeding grounds, as light, climate and wave impacts change to mention only a few phenomena.
Abstract: Water-level fluctuations (WLF) affect the ecological processes and patterns of lakes in several ways. Aquatic habitats and feeding or breeding grounds are gained or lost, as light, climate and wave impacts change to mention only a few phenomena. While the phenomenon of WLF has been studied in many rivers (better known as flood pulse, Junk & Wantzen, 2004) and environmental flows (Coops et al., 2003), so far it has not received due attention in lakes (Coops et al., 2003). A potential reason for why WLF in lakes have been overlooked for such a long time may be that central Europe and North America—the cradles of limnological research—are situated in landscapes which have been shaped by man for long time. Most central European lakes have been regulated since the middle ages; therefore, naturally fluctuating lakes such as Lake Constance (Fig. 1) are rare today.

Journal ArticleDOI
TL;DR: In this article, the explanatory power of three factors, namely international harmonization, transnational communication, and regulatory competition, has been investigated for cross-national policy convergence in twenty-four industrialized countries between 1970 and 2000.
Abstract: In recent years, there is growing interest in the study of cross-national policy convergence. Yet we still have a limited understanding of the phenomenon: Do we observe convergence of policies at all? Under which conditions can we expect that domestic policies converge or rather develop further apart? In this article, we address this research deficit. From a theoretical perspective, we concentrate on the explanatory power of three factors, namely international harmonization, transnational communication, and regulatory competition. In empirical terms, we analyze if and to what extent we can observe convergence of environmental policies across twenty-four industrialized countries between 1970 and 2000. We find an impressive degree of environmental policy convergence between the countries under investigation. This development is mainly caused by international harmonization and, to a considerable degree, also by transnational communication, whereas regulatory competition does not seem to play a role.

Posted Content
TL;DR: In this article, a methodology for modeling time series of realized covariance matrices in order to forecast multivariate risks is proposed, which allows for flexible dynamic dependence patterns and guarantees positive definiteness of the resulting forecasts without imposing parameter restrictions.
Abstract: This paper proposes a methodology for modelling time series of realized covariance matrices in order to forecast multivariate risks. The approach allows for flexible dynamic dependence patterns and guarantees positive definiteness of the resulting forecasts without imposing parameter restrictions. We provide an empirical application of the model, in which we show by means of stochastic dominance tests that the returns from an optimal portfolio based on the model’s forecasts second-order dominate returns of portfolios optimized on the basis of traditional MGARCH models. This result implies that any risk-averse investor, regardless of the type of utility function, would be better-off using our model.

Journal ArticleDOI
TL;DR: The results prove that impaired binding of TLR-ligands from the pathogenic S. aureus strain are not the cause for the inadequate mammary immune response elicited by this pathogen, and the pathogen causing subclinical mastitis impairs NF-kappaB activation in MEC thereby severely weakening the immune response in the udder.

Journal ArticleDOI
TL;DR: In this paper, gender differences in 181 gifted and 181 average-ability sixth graders in achievement, academic self-concept, interest, and motivation in mathematics were investigated, and they found that giftedness was correlated with academic selfconcept and self-esteem.
Abstract: This article investigates gender differences in 181 gifted and 181 average-ability sixth graders in achievement, academic self-concept, interest, and motivation in mathematics. Giftedness was conce...

Journal ArticleDOI
TL;DR: In this article, the relative impact of age and income on individual attitudes towards welfare state policies in advanced industrial democracies has been investigated, i.e. the extent to which the intergenerational conflict supersedes or complements intragenerational conflicts.
Abstract: This article is about the relative impact of age and income on individual attitudes towards welfare state policies in advanced industrial democracies, i.e. the extent to which the intergenerational conflict supersedes or complements intragenerational conflicts. On the basis of a multivariate statistical analysis of the 1996 ISSP Role of Government Data Set for 14 OECD countries, we find considerable age-related differences in welfare state preferences. In particular for the case of education spending, but also for other policy areas, we see that one's position in the life-cycle is a more important predictor of preferences than income. Second, some countries, such as the United States, show a higher salience of the age cleavage across all policy fields, that is, age is a more important line of political preference formation in these countries than in others. Third, country characteristics matter. Although the relative salience of age varies across policy areas, we see - within one policy area - a large variance across countries.