482 research outputs found

    Effects of weight, temperature and behaviour on the circadian rhythm of salivary cortisol in growing pigs

    Get PDF
    In farm animals, salivary cortisol has become a widely used parameter for measuring stress responses. However, only few studies have dealt with basal levels of concentration of cortisol in pigs and its circadian rhythm. The aim of this study was to examine the effects of ambient temperature and thermoregulatory behaviour on the circadian rhythm of salivary cortisol levels in fattening pigs. Subjects were 30 fattening pigs of different weight (60 to 100 kg), kept in six groups in an uninsulated building in pens with partly slatted floors. Saliva samples were taken every 2 h over periods of 24 h at different ambient temperatures at two times in winter and four times in summer. Thermoregulatory behaviour was recorded in the same 24-h time periods. The effect of time of day, body weight, ambient temperature and behaviour on the cortisol level was analysed using a mixed-effects model. Two peaks of cortisol levels per day were found. This circadian pattern became more pronounced with increasing weight and on days where thermoregulatory behaviour was shown. Mean cortisol levels per day were affected by weight but not by thermoregulatory behaviour. From our data, we conclude that long-term variations in cortisol concentration may be influenced by increasing age and weight more than by the respective experimental situation. In assessing animal welfare, it seems more reliable to consider the circadian pattern of cortisol concentration instead of only one value per da

    A Traffic Merging and Generation Framework for Realistic Synthesis of Network Traffic

    Get PDF
    The Internet is steadily growing and is of increasing importance for our economy and society. Due to this increased importance it is also in the focus of attacks, e.g. distributed denial of service (DDoS) attacks. As attackers dynamically change their attack behaviour, novel detection approaches that are able to automatically adjust to these dynamic attacks are needed. To train and test such network anomaly detection systems, it is necessary to provide realistic data. As of today, this area of research suffers from the lack of publicly available datasets that can be used to train and test anomaly detection systems and are exchangeable to allow reproducible research. Therefore, we propose a novel framework that enables researchers and developers to generate customizable synthetic datasets. It not only allows to generate fully-synthetic network traffic, but also to generate semi-synthetic network traffic by merging of multiple network captures from reallive environments. Further, it allows the mapping of IP addresses as well as the modi﬿cation of other header ﬿elds, if desired. This enables researchers and developers to exchange network traces from sensitive environments without revealing any sensitive end-user related information, while perceiving the relevant characteristics of the network(s) and attack(s). In the following, we provide a description of, the problem, our concept and the features of our solution, the architecture and functional model and ﬿nally provide a short summary together with an outlook for future work

    Crystallization studies of Pictet-Spenglerases

    Get PDF
    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.Vita.Includes bibliographical references.Natural products are a rich source of medicinally important molecules. Monoterpene indole alkaloids from plants are an especially important source of therapeutic molecules. Due to the complexity of these molecules, biosynthesis of derivatives is an attractive way of obtaining molecules with potentially new or improved functionality. The rational design of mutants with altered/expanded substrate scope is an important step in engineering organisms to produce such compounds. In monoterpene indole alkaloid biosynthesis, the enzyme strictosidine synthase catalyzes the first committed reaction. This reaction is a Pictet-Spengler coupling between tryptamine and secologanin and produces the biosynthetic intermediate strictosidine, common to all monoterpene indole alkaloids. To better understand the structural features that impart binding selectivity, crystallization studies of this enzyme were performed. The native enzyme and several interesting mutants were studied; co-crystallization experiments with inhibitors and substrates were also performed. Diffraction quality crystals of the native enzyme were obtained following optimization by grid screening, additive screens, and macroseeding. Data on the optimized crystals was collected at the Argonne National Labs synchrotron radiation source. In addition to monoterpene indole alkaloids, the benzylisoquinoline alkaloids are another class of medicinally important plant derived natural products. In a reaction analogous to that catalyzed by strictosidine synthase, the first committed step of benzylisoquinoline biosynthesis is a Pictet-Spengler reaction between 4-hydroxyphenylactetaldehyde and dopamine, catalyzed by the enzyme norcoclaurine synthase. Two different forms of this enzyme have been identified, neither of which shows any homology to strictosidine synthase.(cont.) Structural information for these enzymes could provide general structural features required for enzymatic Pictet-Spengler reactions. Before crystallization, the enzymes were expressed and tested for activity. Once active preparations of protein were available, crystallization studies were performed and crystals were obtained.by William C. Hillmann.S.M

    E7(7) invariant Lagrangian of d=4 N=8 supergravity

    Get PDF
    We present an E7(7) invariant Lagrangian that leads to the equations of motion of d=4 N=8 supergravity without using Lagrange multipliers. The superinvariance of this new action and the closure of the supersymmetry algebra are proved explicitly for the terms that differ from the Cremmer--Julia formulation. Since the diffeomorphism symmetry is not realized in the standard way on the vector fields, we switch to the Hamiltonian formulation in order to prove the invariance of the E7(7) invariant action under general coordinate transformations. We also construct the conserved E7(7)-Noether current of maximal supergravity and we conclude with comments on the implications of this manifest off-shell E7(7)-symmetry for quantizing d=4 N=8 supergravity, in particular on the E7(7)-action on phase space.Comment: 45 pages, references adde

    The SASSCAL contribution to climate observation, climate data management and data rescue in Southern Africa

    Get PDF
    A major task of the newly established "Southern African Science Service Centre for Climate Change and Adaptive Land Management" (SASSCAL; www.sasscal.org) and its partners is to provide science-based environmental information and knowledge which includes the provision of consistent and reliable climate data for Southern Africa. Hence, SASSCAL, in close cooperation with the national weather authorities of Angola, Botswana, Germany and Zambia as well as partner institutions in Namibia and South Africa, supports the extension of the regional meteorological observation network and the improvement of the climate archives at national level. With the ongoing rehabilitation of existing weather stations and the new installation of fully automated weather stations (AWS), altogether 105 AWS currently provide a set of climate variables at 15, 30 and 60 min intervals respectively. These records are made available through the SASSCAL WeatherNet, an online platform providing near-real time data as well as various statistics and graphics, all in open access. This effort is complemented by the harmonization and improvement of climate data management concepts at the national weather authorities, capacity building activities and an extension of the data bases with historical climate data which are still available from different sources. These activities are performed through cooperation between regional and German institutions and will provide important information for climate service related activities

    Counterterms vs. Dualities

    Get PDF
    We investigate and clarify the mutual compatibility of the higher order corrections arising in supergravity and string theory effective actions and the non-linear duality symmetries of these theories. Starting from a conventional tree level action leading to duality invariant equations of motion, we show how to accommodate duality invariant counterterms given as functionals of both electric and magnetic fields in a perturbative expansion, and to deduce from them a non-polynomial bona fide action satisfying the Gaillard-Zumino constraint. There exists a corresponding consistency constraint in the non-covariant Henneaux-Teitelboim formalism which ensures that one can always restore diffeomorphism invariance by perturbatively solving this functional identity. We illustrate how this procedure works for the R^2 \nabla F \nabla F and F^4 counterterms in Maxwell theory.Comment: 15 page

    Resilience Factors in Women with Severe Early-Life Maltreatment

    Get PDF
    INTRODUCTION: Early-life maltreatment (ELM) has long-lasting negative consequences and is the most important general risk factor for mental disorders. Nevertheless, a number of maltreated children grow up to become healthy adults and have therefore been called ‘resilient’. The aim of the current study is to investigate ‘resilience factors’ in the context of severe ELM. METHOD: The study was part of the large multicenter project Understanding and Breaking the Intergenerational Cycle of Abuse (UBICA). A total of 89 women were examined, 33 with ELM and at least one lifetime mental disorder (nonresilient), 19 with ELM but without lifetime mental disorders (resilient), and 37 without ELM and without lifetime mental disorders (controls). ELM and other circumstances before the age of 18 years were assessed with the Childhood Experience of Care and Abuse (CECA) Interview. Additional relevant person and situation factors were measured with the Structured Clinical Interview for Mental Disorders (SCID-I), International Personality Disorder Exam-ination (IPDE), Difficulties in Emotion Regulation Scale (DERS), Vulnerable Attachment Style Questionnaire (VASQ), Barratt Impulsiveness Scale (BIS), NEO Five-Factor Inventory (NEO-FFI), and Multiple-Choice Vocabulary Intelligence Test (MWT-B). Factor analyses and paired t tests were performed to identify those variables which differentiate best between the three groups. In addition, a discriminant analysis was conducted to detect the accuracy of assigning women to their specific group. RESULTS: The factor analyses revealed 10 resilience factors based on which we could correctly assign 80% of the women to their group in the discriminant analysis. t tests of factor scores showed that resilient and nonresilient maltreated women mainly differed in current individual attributes (e.g. impulsivity, attachment style), while resilient and nonresilient maltreated women differed from controls in both their current individual attributes and their view of their situation as a child. CONCLUSION: The 4 variables neuroticism, extraversion, vulnerable attachment, and perceived loneliness during childhood were identified as most important in differentiating all three examined groups. Therefore, prevention and intervention programs focusing on the individual’s development of secure attachment and social competence may be of particular importance in the context of ELM

    Duality Invariant M-theory: Gauged supergravities and Scherk-Schwarz reductions

    Full text link
    We consider the reduction of the duality invariant approach to M-theory by a U-duality group valued Scherk-Schwarz twist. The result is to produce potentials for gauged supergravities that are normally associated with non-geometric compactifications. The local symmetry reduces to gauge transformations with the gaugings exactly matching those of the embedding tensor approach to gauged supergravity. Importantly, this approach now includes a nontrivial dependence of the fields on the extra coordinates of the extended space.Comment: 22 pages Latex; v2: typos corrected and references adde

    Generalized E(7(7)) coset dynamics and D=11 supergravity

    Full text link
    The hidden on-shell E(7(7)) symmetry of maximal supergravity is usually discussed in a truncation from D=11 to four dimensions. In this article, we reverse the logic and start from a theory with manifest off-shell E(7(7)) symmetry inspired by West's coset construction. Following de Wit's and Nicolai's idea that a 4+56 dimensional "exceptional geometry" underlies maximal supergravity, we construct the corresponding Lagrangian and the supersymmetry variations for the 56 dimensional subsector. We prove that both the dynamics and the supersymmetry coincide with D=11 supergravity in a truncation to d=7 in the expected way.Comment: 42 pages, v2: references adde

    Effects of mesenchymal stromal cells versus serum on tendon healing in a controlled experimental trial in an equine model

    Get PDF
    Abstract Background Mesenchymal stromal cells (MSC) have shown promising results in the treatment of tendinopathy in equine medicine, making this therapeutic approach seem favorable for translation to human medicine. Having demonstrated that MSC engraft within the tendon lesions after local injection in an equine model, we hypothesized that they would improve tendon healing superior to serum injection alone. Methods Quadrilateral tendon lesions were induced in six horses by mechanical tissue disruption combined with collagenase application 3 weeks before treatment. Adipose-derived MSC suspended in serum or serum alone were then injected intralesionally. Clinical examinations, ultrasound and magnetic resonance imaging were performed over 24 weeks. Tendon biopsies for histological assessment were taken from the hindlimbs 3 weeks after treatment. Horses were sacrificed after 24 weeks and forelimb tendons were subjected to macroscopic and histological examination as well as analysis of musculoskeletal marker expression. Results Tendons injected with MSC showed a transient increase in inflammation and lesion size, as indicated by clinical and imaging parameters between week 3 and 6 (p < 0.05). Thereafter, symptoms decreased in both groups and, except that in MSC-treated tendons, mean lesion signal intensity as seen in T2w magnetic resonance imaging and cellularity as seen in the histology (p < 0.05) were lower, no major differences could be found at week 24. Conclusions These data suggest that MSC have influenced the inflammatory reaction in a way not described in tendinopathy studies before. However, at the endpoint of the current study, 24 weeks after treatment, no distinct improvement was observed in MSC-treated tendons compared to the serum-injected controls. Future studies are necessary to elucidate whether and under which conditions MSC are beneficial for tendon healing before translation into human medicine
    corecore