1,764 research outputs found
Pion scattering poles and chiral symmetry restoration
Using unitarized Chiral Perturbation Theory methods, we perform a detailed
analysis of the scattering poles and behaviour
when medium effects such as temperature or density drive the system towards
Chiral Symmetry Restoration. In the analysis of real poles below threshold, we
show that it is crucial to extend properly the unitarized amplitudes so that
they match the perturbative Adler zeros. Our results do not show threshold
enhancement effects at finite temperature in the channel, which
remains as a pole of broad nature. We also implement T=0 finite density effects
related to chiral symmetry restoration, by varying the pole position with the
pion decay constant. Although this approach takes into account only a limited
class of contributions, we reproduce the expected finite density restoration
behaviour, which drives the poles towards the real axis, producing threshold
enhancement and bound states. We compare our results with several
model approaches and discuss the experimental consequences, both in
Relativistic Heavy Ion Collisions and in and
reactions in nuclei.Comment: 17 pages, 9 figures, final version to appear in Phys.Rev.D, added
comments and reference
Spectral-analysis-surface-waves-method in ground characterization
The prediction of train induced vibration levels in structures close to railway tracks before track construction starts is important in order to avoid having to implement costly mitigation measures afterwards. The used models require an accurate characterization of the propagation medium i.e. the soil layers. To this end the spectral analysis of surface waves (SASW) method has been chosen among the active surface waves techniques available. As dynamic source a modal sledge hammer has been used. The generated vibrations have been measured at known offsets by means of several accelerometers. There are many parameters involved in estimating the experimental dispersion curve and, later on, thickness and propagation velocities of the different layers. Tests have been carried out at the Segovia railway station. Its main building covers some of the railway tracks and vibration problems in the building should be avoided. In the paper these tests as well as the influence of several parameters on the estimated soil profile will be detailed
Bulk viscosity of the massive Gross-Neveu model
A calculation of the bulk viscosity for the massive Gross-Neveu model at zero
fermion chemical potential is presented in the large- limit. This model
resembles QCD in many important aspects: it is asymptotically free, has a
dynamically generated mass gap, and for zero bare fermion mass it is scale
invariant at the classical level (broken through the trace anomaly at the
quantum level). For our purposes, the introduction of a bare fermion mass is
necessary to break the integrability of the model, and thus to be able to study
momentum transport. The main motivation is, by decreasing the bare mass, to
analyze whether there is a correlation between the maximum in the trace anomaly
and a possible maximum in the bulk viscosity, as recently conjectured. After
numerical analysis, I find that there is no direct correlation between these
two quantities: the bulk viscosity of the model is a monotonously decreasing
function of the temperature. I also comment on the sum rule for the spectral
density in the bulk channel, as well as on implications of this analysis for
other systems.Comment: v2: 3->3 processes included, conclusions unchanged. Comments and
references added. Typos corrected. To appear in Phys. Rev.
Dynamic factors for underpasses in high speed train lines
Los pasos inferiores son muy numerosos en las líneas de ferrocarril. Su comportamiento dinámico ha recibido mucha menos atención que el de otras estructuras como los puentes, pero su elevado número hace que su estudio sea económicamente relevante con vista a optimizar su forma, manteniendo la seguridad. El proyecto de puentes según el Eurocódigo incluye comprobaciones de estados límite de tensiones bajo carga dinámica. En el caso de pasos inferiores, las comprobaciones pueden resultar tan costosas como aquellas de puentes, pese a que su coste es mucho menor. Por tanto, se impone la búsqueda de unas reglas de cálculo simplificado que pongan en consonancia el coste de la estructura con el esfuerzo necesario para su proyecto. Este artículo propone un conjunto de reglas basadas en un estudio paramétrico.Underpasses are common in modern railway lines. Wildlife corridors and drainage conduits often fall into this category of partially buried structures. Their dynamic behavior has received far less attention than that of other structures such as bridges, but their large number makes their study an interesting challenge from the viewpoint of safety and cost savings. The bridge design rules in accordance with the Eurocode involve checks on stresses according to dynamic loading. In the case of underpasses, those checks may be as much as those for bridges. Therefore, simplified design rules may align the design effort with their cost. Such a set of rules may provide estimations of response parameters based on the key parameters influencing the result. This paper contains a proposal based on a parametric study.Peer Reviewe
Searching for Scuti-type pulsation and characterising northern pre-main-sequence field stars
A photometric variability study of a sample of northern field stars, which
previously classified as either PMS or Herbig Ae/Be objects, has been
undertaken with the purpose of detecting {\delta} Scuti-type pulsations.
Determination of physical parameters for these stars has also been carried out
to locate them on the HR diagram and check the instability strip for this type
of pulsators. Multichannel photomultiplier and CCD time series photometry in
the uvby Str\"omgren and BVI Johnson bands were obtained during four
consecutive years from 2007 to 2010. The light curves have been analysed, and a
variability criterion has been established. Among the objects classified as
variable stars, we have selected those which present periodicities above 4
d^(-1), which was established as the lowest limit for {\delta} Scuti-type
pulsations in this investigation. Finally, these variable stars have been
placed in a colour-magnitude diagram using the physical parameters derived with
the collected uvby{\beta} Str\"omgren-Crawford photometry. Five PMS {\delta}
Scuti- and three probable {\beta} Cephei-type stars have been detected. Two
additional PMS {\delta} Scuti stars are also confirmed in this work. Moreover,
three new {\delta} Scuti- and two {\gamma} Doradus-type stars have been
detected among the main-sequence objects used as comparison or check stars.Comment: Accepted for publication in Section 14. Catalogs and data of
Astronomy and Astrophysics. The official date of acceptance is 17/06/2014. 12
pages, 4 figures and 8 table
Complejo granuloma eosinofílico
El complejo granuloma eosinofílico agrupa tres entidades clínico/histológicas denominadas granuloma colagenolítico, placa eosinofílica y úlcera indolente. En el presente artículo se describe su etiología y sus aspectos clínicos y terapéuticos.The eosinophilic granuloma complex is comprised of three clinical/histological entities: collagenolytic granuloma, eosinophilic plaque and indolent ulcer. In this article, its etiology, clinical aspects and therapy are discussed
Targeted-pig trial on safety and immunogenicity of serum-derived extracellular vesicles enriched fractions obtained from Porcine Respiratory and Reproductive virus infections
The Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is the etiological agent of one of the
most important swine diseases with a significant economic burden worldwide. Unfortunately, available
vaccines are partially effective highlighting the need of novel approaches. Previously, antigenic viral
proteins were described in serum-derived extracellular vesicles (EVs) from pigs previously infected with
PRRSV. Here, a targeted-pig trial was designed to determine the safety and immunogenicity of such
extracellular vesicles enriched fractions. Our results showed that immunizations with EV-enriched
fractions from convalescence animals in combination with montanide is safe and free of virus as
immunizations with up-to two milligrams of EV-enriched fractions did not induce clinical symptoms,
adverse effects and detectable viral replication. In addition, this vaccine formulation was able to elicit
specific humoral IgG immune response in vaccinated animals, albeit variably. Noticeably, sera from
vaccinated animals was diagnosed negative when tested for PRRSV using a commercial ELISA test;
thus, indicating that this new approach differentiates vaccinated from infected animals. Lastly, after
priming animals with EV-enriched fractions from sera of convalescence animals and boosting them with
synthetic viral peptides identified by mass spectrometry, a distinctive high and specific IFN-γ response
was elicited. Altogether, our data strongly suggest the use of serum EV-enriched fractions as a novel
vaccine strategy against PRRSV.Anti-CD9, Anti-CD63 and anti-CD81 antibodies were kindly donated by Francisco Sánchez-Madrid and Maria Yañez-Mo, Hospital de la Princesa, Madrid, Spain. The authors wish to particularly thank Glòria Abella for her collaboration in conducting the field study and to Marta Alcobé, Miriam Moron Font and Paula Crego Mendez for technical assistance. This study received support from Innovex Therapeutics S.L., Pinsos del Segre SA, Granja Casanyé, Grup de Sanejament Porci (GSP, Lleida, Spain) and the FEDER project (COMRDI16-1-0035-03). Sergio Montanter-Tarbes is an industrial doctorate awarded by the Government of Catalonia, Spain (No. 2014 DI 044). ISGlobal and IGTP are members of the CERCA Programme, Generalitat de Catalunya
The influence of wildfires on aerosol size distributions in rural areas
The number of particles and their size distributions were measured in a rural area, during the summer, using a PCASP-X. The aim was to study the influence of wildfires on particle size distributions. The comparative studies carried out reveal an average increase of around ten times in the number of particles in the fine mode, especially in sizes between 0.10 and 0.14 μm, where the increase is of nearly 20 times. An analysis carried out at three different points in time--before, during, and after the passing of the smoke plume from the wildfires--shows that the mean geometric diameter of the fine mode in the measurements affected by the fire is smaller than the one obtained in the measurements carried out immediately before and after (0.14 μm) and presents average values of 0.11 μm.publishe
Síndrome uveodermatológico en el perro
Se describe un caso de síndrome uveodermatológico en un perro Mastín español, macho, de 2 años. Los signos clínicos observados eran similares al síndrome de Vogt- Koyanagi-Harada humano y se caracterizaban por una uveitis asociada a una despigmentación y erosión cutánea y mucocutánea en cara, escroto, región perianal y almohadillas plantares. El estudio histopatológico reveló una dermatitis liquenoide, en la que predominaban los macrófagos. El tratamiento se basó en la administración oral de prednisona asociada a una terapia ocular tópica a base de atropina y corticosteroides. Al cabo de 8 meses las lesiones cutáneas y mucosas remitieron completamente.A case of uveodermatologic syndrome in a male 2 year old, Spanish Mastiff is described. The clinical signs found, namely uvezitis associated with cutaneus and mucocutaneous depigmentation and erosions of the face, scrotum, perianal region and footpads, were similar to those of the human Vogt-Koyanagi-Harada syndrome. The histopathological study showed a lichenoid dermatitis with prevalence of macrophages. The treatment encompassed the administration of prednisone per os and topical ocular therapy with corticosteroids associated with atropin e. After 8 months the cutaneous and mucosal Iesions had completely remitted
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