115 research outputs found

    Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA

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    Inclusive charm and beauty cross sections are measured in e − p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q 2≤2000 GeV2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb−1. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions

    Study of Charm Fragmentation into D^{*\pm} Mesons in Deep-Inelastic Scattering at HERA

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    The process of charm quark fragmentation is studied using D±D^{*\pm} meson production in deep-inelastic scattering as measured by the H1 detector at HERA. Two different regions of phase space are investigated defined by the presence or absence of a jet containing the D±D^{*\pm} meson in the event. The parameters of fragmentation functions are extracted for QCD models based on leading order matrix elements and DGLAP or CCFM evolution of partons together with string fragmentation and particle decays. Additionally, they are determined for a next-to-leading order QCD calculation in the fixed flavour number scheme using the independent fragmentation of charm quarks to D±D^{*\pm} mesons.Comment: 33 pages, submitted to EPJ

    A mammalian cell based FACS-panning platform for the selection of HIV-1 envelopes for vaccine development

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    An increasing number of broadly neutralizing monoclonal antibodies (bnMAb) against the HIV-1 envelope (Env) protein has been discovered recently. Despite this progress, vaccination efforts with the aim to re-elicit bnMAbs that provide protective immunity have failed so far. Herein, we describe the development of a mammalian cell based FACS-panning method in which bnMAbs are used as tools to select surface-exposed envelope variants according to their binding affinity. For that purpose, an HIV-1 derived lentiviral vector was developed to infect HEK293T cells at low multiplicity of infection (MOI) in order to link Env phenotype and genotype. For proof of principle, a gp145 Env model-library was established in which the complete V3 domain was substituted by five strain specific V3 loop sequences with known binding affinities to nMAb 447-52D, respectively. Env genes were recovered from selected cells by PCR, subcloned into a lentiviral vector (i) to determine and quantify the enrichment nMAb binders and (ii) to generate a new batch of transduction competent particles. After 2 selection cycles the Env variant with highest affinity was enriched 20-fold and represented 80% of the remaining Env population. Exploiting the recently described bnMAbs, this procedure might prove useful in selecting Env proteins from large Env libraries with the potential to elicit bnMAbs when used as vaccine candidates

    Prime-boost immunization of rabbits with HIV-1 gp120 elicits potent neutralization activity against a primary viral isolate

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    <div><p>Development of a vaccine for HIV-1 requires a detailed understanding of the neutralizing antibody responses that can be experimentally elicited to difficult-to-neutralize primary isolates. Rabbits were immunized with the gp120 subunit of HIV-1 JR-CSF envelope (Env) using a DNA-prime protein-boost regimen. We analyzed five sera that showed potent autologous neutralizing activity (IC50s at ∼10<sup>3</sup> to 10<sup>4</sup> serum dilution) against pseudoviruses containing Env from the primary isolate JR-CSF but not from the related isolate JR-FL. Pseudoviruses were created by exchanging each variable and constant domain of JR-CSF gp120 with that of JR-FL or with mutations in putative N-glycosylation sites. The sera contained different neutralizing activities dependent on C3 and V5, C3 and V4, or V4 regions located on the glycan-rich outer domain of gp120. All sera showed enhanced neutralizing activity toward an Env variant that lacked a glycosylation site in V4. The JR-CSF gp120 epitopes recognized by the sera are generally distinct from those of several well characterized mAbs (targeting conserved sites on Env) or other type-specific responses (targeting V1, V2, or V3 variable regions). The activity of one serum requires specific glycans that are also important for 2G12 neutralization and this serum blocked the binding of 2G12 to gp120. Our findings show that different fine specificities can achieve potent neutralization of HIV-1, yet this strong activity does not result in improved breadth.</p> </div

    Jet production in ep collisions at high Q(2) and determination of alpha(s)

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    The production of jets is studied in deep-inelastic e(+/-) p scattering at large negative four momentum transfer squared 150 LT Q(2) LT 15000 GeV2 using HERA data taken in 1999-2007, corresponding to an integrated luminosity of 395 pb(-1). Inclusive jet, 2-jet and 3-jet cross sections, normalised to the neutral current deep-inelastic scattering cross sections, are measured as functions of Q(2), jet transverse momentum and proton momentum fraction. The measurements are well described by perturbative QCD calculations at next-to-leading order corrected for hadronisation effects. The strong coupling as determined from these measurement

    Reliability assessment and failure mode analysis of MEMS accelerometers for space applications

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    In the present work, the reliability assessment of capacitive MEMS accelerometers of 3 different suppliers (codenamed A, B, and C) for their use in space applications was performed. The developed reliability assessment testing program addressed specific severities of space missions, such as mechanical shocks and vibrations during take-off and rocket stages separation, high temperature gradients and radiation endurance during in-orbit operation. The main aim of the testing was to evaluate the robustness and reliability limits of MEMS devices by overstressing their specific properties through dedicated tests. Typical failures modes were analyzed and root-causes identified on the devices' subsystem level: MEMS structure, ASIC, interconnecting wires, and package. Overall results of the performed reliability assessment tests and failure mode analyses suggest that the most specific MEMS components, namely the microstructures, do not themselves constitute the failure causes. Following the observations, other components, e.g. interconnects, ASIC or packaging, exhibit lower reliability limits to the specific stresses of the space harsh conditions. Comparative analysis of three accelerometers from various suppliers (designs A, B, and C) suggests the design A (in a hermetic ceramic package) to exhibit the best overall reliability for space-specific application conditions. Design B also shows good robustness. However, its non-hermetic packaging makes it unsuitable for the direct use for space applications in the current state. Utilization of a hermetic package and improvement of the wire-bonding temperature resistance would significantly improve this design. Accelerometers of supplier C (in a hermetic ceramic package) have a trend of occasional “infant mortality” early failures. It is therefore very important to perform burn-in and initial pre-screening for these devices. Another strong weak point for this design is related to a low radiation endurance, which shall be significantly improved

    Oxime K033-reactivation activity of cholinesterases inhibited by various nerve agents and organophosphorus pesticides

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    Background: Oxime K033 was considered a promising drug candidate originally developed for the treatment of nerve agent poisoning. This study summarizes its potency to reactivate in vitro acetylcholinesterase inhibited by several nerve agents (tabun, sarin, cyclosarin, soman, VX, Russian VX), mimic agent (DFP) and organophosphorus pesticide (chlorpyrifos) to show whether this compound might be used in cases of nerve agent or pesticide poisoning and considered as a so-called "broad spectrum reactivator". Methods: Moreover, docking studies of tested oxime with human AChE (HssAChE) complexed with several OPs were performed in order to verify its stability, binding modes and ability to adopt favourable conformations and to perform the reactivation reaction with each OP under experimental study. Results & Conclusion: According to the obtained results, K033 could not be considered a universal antidote due to its poor reactivation activity in the case of tabun-, soman- and DFP-inhibited rat acetylcholinesterase. On the contrary, its very good in vitro potency in human-relevant doses for cyclosarin inhibition is highlighted.Web of Science15111130112

    Development of small bisquaternary cholinesterase inhibitors as drugs for pre-treatment of nerve agent poisonings

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    Kamil Kuca,1,2 Jana Zdarova Karasova,2,3 Ondrej Soukup,2 Jiri Kassa,3 Eva Novotna,2 Vendula Sepsova,2,3 Anna Horova,2 Jaroslav Pejchal,3 Martina Hrabinova,2,3 Eva Vodakova,2 Daniel Jun,2,3 Eugenie Nepovimova,1,2 Martin Valis,4 Kamil Musilek1,2 1Department of Chemistry, Faculty of Science, University of Hradec Kralove, 2Biomedical Research Center, University Hospital Hradec Kralove, 3Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, 4Department of Neurology, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic Background: Intoxication by nerve agents could be prevented by using small acetylcholinesterase inhibitors (eg, pyridostigmine) for potentially exposed personnel. However, the serious side effects of currently used drugs led to research of novel potent molecules for prophylaxis of organophosphorus intoxication. Methods: The molecular design, molecular docking, chemical synthesis, in vitro methods (enzyme inhibition, cytotoxicity, and nicotinic receptors modulation), and in vivo methods (acute toxicity and prophylactic effect) were used to study bispyridinium, bisquinolinium, bisisoquinolinium, and pyridinium-quinolinium/isoquinolinium molecules presented in this study. Results: The studied molecules showed non-competitive inhibitory ability towards human acetylcholinesterase in vitro that was further confirmed by molecular modelling studies. Several compounds were selected for further studies. First, their cytotoxicity, nicotinic receptors modulation, and acute toxicity (lethal dose for 50% of laboratory animals [LD50]; mice and rats) were tested to evaluate their safety with promising results. Furthermore, their blood levels were measured to select the appropriate time for prophylactic administration. Finally, the protective ratio of selected compounds against soman-induced toxicity was determined when selected compounds were found similarly potent or only slightly better to standard pyridostigmine. Conclusion: The presented small bisquaternary molecules did not show overall benefit in prophylaxis of soman-induced in vivo toxicity. Keywords: AChE inhibitors, prophylaxis, pre-treatment, nerve agents, toxicity, soma

    Virtue ethics and social psychology

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    Virtue ethics has emerged as an alternative to deontological and utilitarian theory in recent moral philosophy. The basic notion of virtue ethics is to reassert the importance of virtuous character in ethical judgement in contrast to the emphasis on principles and consequences. Since questions of virtue have been largely neglected in modern moral theory, there has been a return to Aristotle’s account of virtue as character. This in turn has been questioned as the basis of virtue ethics and there has been a search for alternative accounts of moral agency. One aspect of this critical reflection on virtue ethics is an engagement with social psychology as a source of criticism of the Aristotelian conception of character and as a more plausible alternative foundation for a theory of moral character with contemporary relevance. This paper aims to introduce this area of moral theory to a psychological audience and reflect on the interpretation of social psychological theory and evidence in criticisms of virtuous character, focusing on the use of Milgram’s (1974) experiments on obedience to authority as an argument for situationism. A number of questions emerge concerning the interpretation and use of social psychological theory and evidence in debates within moral philosophy

    2-Propargylamino-naphthoquinone derivatives as multipotent agents for the treatment of Alzheimer's disease

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    Alzheimer's disease is a progressive brain disorder with characteristic symptoms and several pathological hallmarks. The concept of “one drug, one target” has not generated any new drugs since 2004. The new era of drug development in the field of AD builds upon rationally designed multi-target directed ligands that can better address the complexity of AD. Herewith, we designed ten novel derivatives of 2-propargylamino-naphthoquinone. The biological evaluation of these compounds includes inhibition of monoamine oxidase A/B, inhibition of amyloid-beta aggregation, radical-scavenging, and metal-chelating properties. Some of the compounds possess low cytotoxicity profile with an anti-inflammatory ability in the lipopolysaccharide-stimulated cellular model. All these features warrant their further testing in the field of AD.This work was supported by a grant of the Ministry of Defence “Long Term Development Plan” Medical Aspects of Weapons of Mass Destruction of the Faculty of Military Health Sciences, University of Defence; by the Ministry of Education, Youth and Sports of Czech Republic (project ERDF IT4N no. CZ.02.1.01/0.0/0.0/ 18_069/0010054), by EU COST Action (CA15135: “Multi-target paradigm for innovative ligand identification in the drug discovery process (MuTaLig)"), and by MH CZ - DRO (University HospitalHradec Kralove, No. 00179906). We also thank the Scientific Grant Agency (VEGA Project 1/0482/20) and Research and Development Support Agency (APVV-15-0079 and APVV-19-0087). Marvin was used for drawing, displaying, and characterizing chemical structures, substructures and reactions, Marvin 20.15.0, ChemAxon (https://www.chemaxon.com)
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