536 research outputs found
A comparison between methods of analytical continuation for bosonic functions
In this article we perform a critical assessment of different known methods
for the analytical continuation of bosonic functions, namely the maximum
entropy method, the non-negative least-square method, the non-negative Tikhonov
method, the Pad\'e approximant method, and a stochastic sampling method. Three
functions of different shape are investigated, corresponding to three
physically relevant scenarios. They include a simple two-pole model function
and two flavours of the non-interacting Hubbard model on a square lattice, i.e.
a single-orbital metallic system and a two-orbitals insulating system. The
effect of numerical noise in the input data on the analytical continuation is
discussed in detail. Overall, the stochastic method by Mishchenko et al. [Phys.
Rev. B \textbf{62}, 6317 (2000)] is shown to be the most reliable tool for
input data whose numerical precision is not known. For high precision input
data, this approach is slightly outperformed by the Pad\'e approximant method,
which combines a good resolution power with a good numerical stability.
Although none of the methods retrieves all features in the spectra in the
presence of noise, our analysis provides a useful guideline for obtaining
reliable information of the spectral function in cases of practical interest.Comment: 13 pages, 9 figure
Standard model of the rare-earths, analyzed from the Hubbard I approximation
In this work we examine critically the electronic structure of the rare-earth
elements by use of the so-called Hubbard I approximation. From the theoretical
side all measured features of both occupied and unoccupied states are
reproduced, without significant deviations between observations and theory. We
also examine cohesive properties like the equilibrium volume and bulk modulus,
where we find, in general, a good agreement between theory and measurements. In
addition we have reproduced the spin and orbital moments of these elements, as
they are reflected from measurements of the saturation moment. We have also
employed the Hubbard I approximation to extract the interatomic exchange
parameters of an effective spin Hamiltonian for the heavy rare earths. We show
that the Hubbard I approximation gives results which are consistent with
calculations where electrons are treated as core states for Gd. The latter
approach was also used to address the series of the heavy/late rare-earths. Via
Monte Carlo simulations we obtained ordering temperatures which reproduce
measurements within about . We have further illustrated the accuracy of
these exchange parameters by comparing measured and calculated magnetic
configurations for the heavy rare earths and the magnon dispersion for Gd. The
Hubbard I approximation is compared to other theories of the electronic
structure, and we argue that it is superior. We discuss the relevance of our
results in general, and how this makes it possible to treat the electronic
structure of materials containing rare-earth elements, such as permanent
magnets, magnetostrictive compounds, photovoltaics, optical fibers, topological
insulators, and molecular magnets.Comment: 21 pages, 14 figures, 2 tables, 4 appendice
IL-18 Does not Increase Allergic Airway Disease in Mice When Produced by BCG
Whilst BCG inhibits allergic airway responses in murine models, IL-18 has adversary effects depending on its environment. We therefore constructed a BCG strain producing murine IL-18 (BCG-IL-18) and evaluated its efficiency to prevent an asthma-like reaction in mice. BALB/cByJ mice were sensitized (day (D) 1 and D10) by intraperitoneal injection of ovalbumin (OVA)-alum and primary (D20–22) and secondary (D62, 63) challenged with OVA aerosols. BCG or BCG-IL-18 were intraperitonealy administered 1 hour before each immunization (D1 and D10). BCG-IL-18 and BCG were shown to similarly inhibit the development of AHR, mucus production, eosinophil influx, and local Th2 cytokine production in BAL, both after the primary and secondary challenge.
These data show that IL-18 did not increase allergic airway responses in the context of the mycobacterial infection, and suggest that BCG-IL-18 and BCG are able to prevent the development of local Th2 responses and therefore inhibit allergen-induced airway responses even after restimulation
Unconventional, adenosine-producing suppressor T cells induced by dendritic cells exposed to BPZE1 pertussis vaccine
Vaccine responses in newborns.
Immunisation of the newborn represents a key global strategy in overcoming morbidity and mortality due to infection in early life. Potential limitations, however, include poor immunogenicity, safety concerns and the development of tolerogenicity or hypo-responsiveness to either the same antigen and/or concomitant antigens administered at birth or in the subsequent months. Furthermore, the neonatal immunological milieu is polarised towards Th2-type immunity with dampening of Th1-type responses and impaired humoral immunity, resulting in qualitatively and quantitatively poorer antibody responses compared to older infants. Innate immunity also shows functional deficiency in antigen-presenting cells: the expression and signalling of Toll-like receptors undergo maturational changes associated with distinct functional responses. Nevertheless, the effectiveness of BCG, hepatitis B and oral polio vaccines, the only immunisations currently in use in the neonatal period, is proof of concept that vaccines can be successfully administered to the newborn via different routes of delivery to induce a range of protective mechanisms for three different diseases. In this review paper, we discuss the rationale for and challenges to neonatal immunisation, summarising progress made in the field, including lessons learnt from newborn vaccines in the pipeline. Furthermore, we explore important maternal, infant and environmental co-factors that may impede the success of current and future neonatal immunisation strategies. A variety of approaches have been proposed to overcome the inherent regulatory constraints of the newborn innate and adaptive immune system, including alternative routes of delivery, novel vaccine configurations, improved innate receptor agonists and optimised antigen-adjuvant combinations. Crucially, a dual strategy may be employed whereby immunisation at birth is used to prime the immune system in order to improve immunogenicity to subsequent homologous or heterologous boosters in later infancy. Similarly, potent non-specific immunomodulatory effects may be elicited when challenged with unrelated antigens, with the potential to reduce the overall risk of infection and allergic disease in early life
Surface-Initiated Polymer Brushes in the Biomedical Field: Applications in Membrane Science, Biosensing, Cell Culture, Regenerative Medicine and Antibacterial Coatings
A Deep Insight into the Sialome of Rhodnius neglectus, a vector of chagas disease
Background Triatomines are hematophagous insects that act as vectors of Chagas disease. Rhodnius neglectus is one of these kissing bugs found, contributing to the transmission of this American trypanosomiasis. The saliva of hematophagous arthropods contains bioactive molecules responsible for counteracting host haemostatic, inflammatory, and immuneresponses. Methods/Principal Findings Next generation sequencing and mass spectrometry-based protein identification were performed to investigate the content of triatomine R. neglectus saliva.We deposited 4,230 coding DNA sequences (CDS) in GenBank. A set of 636 CDS of proteins of putative secretory nature was extracted from the assembled reads, 73 of them confirmed by proteomic analysis. The sialome of R. neglectus was characterized and serine protease transcripts detected. The presence of ubiquitous protein families was revealed, including lipocalins, serine protease inhibitors, and antigen-5. Metalloproteases, disintegrins, and odorant binding protein families were less abundant. Conclusions/Significance The data presented improve our understanding of hematophagous arthropod sialomes, and aid in understanding hematophagy and the complex interplay among vectors and their vertebrate hosts
Highlights of the 11th International Bordetella Symposium: From basic biology to vaccine development
Pertussis is a severe respiratory disease caused by infection with the bacterial pathogen Bordetella pertussis. The disease affects individuals of all ages but is particularly severe and sometimes fatal in unvaccinated young infants. Other Bordetella species cause diseases in humans, animals, and birds. Scientific, clinical, public health, vaccine company, and regulatory agency experts on these pathogens and diseases gathered in Buenos Aires, Argentina from 5 to 8 April 2016 for the 11th International Bordetella Symposium to discuss recent advances in our understanding of the biology of these organisms, the diseases they cause, and the development of new vaccines and other strategies to prevent these diseases. Highlights of the meeting included pertussis epidemiology in developing nations, genomic analysis of Bordetella biology and evolution, regulation of virulence factor expression, new model systems to study Bordetella biology and disease, effects of different vaccines on immune responses, maternal immunization as a strategy to prevent newborn disease, and novel vaccine development for pertussis. In addition, the group approved the formation of an International Bordetella Society to promote research and information exchange on bordetellae and to organize future meetings. A new Bordetella.org website will also be developed to facilitate these goals.Instituto de Biotecnologia y Biologia Molecula
Highlights of the 11th International Bordetella Symposium: From basic biology to vaccine development
Pertussis is a severe respiratory disease caused by infection with the bacterial pathogen Bordetella pertussis. The disease affects individuals of all ages but is particularly severe and sometimes fatal in unvaccinated young infants. Other Bordetella species cause diseases in humans, animals, and birds. Scientific, clinical, public health, vaccine company, and regulatory agency experts on these pathogens and diseases gathered in Buenos Aires, Argentina from 5 to 8 April 2016 for the 11th International Bordetella Symposium to discuss recent advances in our understanding of the biology of these organisms, the diseases they cause, and the development of new vaccines and other strategies to prevent these diseases. Highlights of the meeting included pertussis epidemiology in developing nations, genomic analysis of Bordetella biology and evolution, regulation of virulence factor expression, new model systems to study Bordetella biology and disease, effects of different vaccines on immune responses, maternal immunization as a strategy to prevent newborn disease, and novel vaccine development for pertussis. In addition, the group approved the formation of an International Bordetella Society to promote research and information exchange on bordetellae and to organize future meetings. A new Bordetella.org website will also be developed to facilitate these goals.Instituto de Biotecnologia y Biologia Molecula
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