103 research outputs found
Charged-Higgs phenomenology in the Aligned two-Higgs-doublet model
The alignment in flavour space of the Yukawa matrices of a general
two-Higgs-doublet model results in the absence of tree-level flavour-changing
neutral currents. In addition to the usual fermion masses and mixings, the
aligned Yukawa structure only contains three complex parameters, which are
potential new sources of CP violation. For particular values of these three
parameters all known specific implementations of the model based on discrete
Z_2 symmetries are recovered. One of the most distinctive features of the
two-Higgs-doublet model is the presence of a charged scalar. In this work, we
discuss its main phenomenological consequences in flavour-changing processes at
low energies and derive the corresponding constraints on the parameters of the
aligned two-Higgs-doublet model.Comment: 46 pages, 19 figures. Version accepted for publication in JHEP.
References added. Discussion slightly extended. Conclusions unchange
The mu - e Conversion in Nuclei, mu --> e gamma, mu --> 3e Decays and TeV Scale See-Saw Scenarios of Neutrino Mass Generation
We perform a detailed analysis of lepton flavour violation (LFV) within
minimal see-saw type extensions of the Standard Model (SM), which give a viable
mechanism of neutrino mass generation and provide new particle content at the
electroweak scale. We focus, mainly, on predictions and constraints set on each
scenario from mu --> e gamma, mu --> 3e and mu - e conversion in the nuclei. In
this class of models, the flavour structure of the Yukawa couplings between the
additional scalar and fermion representations and the SM leptons is highly
constrained by neutrino oscillation measurements. In particular, we show that
in some regions of the parameters space of type I and type II see-saw models,
the Dirac and Majorana phases of the neutrino mixing matrix, the ordering and
hierarchy of the active neutrino mass spectrum as well as the value of the
reactor mixing angle theta_{13} may considerably affect the size of the LFV
observables. The interplay of the latter clearly allows to discriminate among
the different low energy see-saw possibilities.Comment: Expressions for the factors |C_{me}|^2 and |C_{mu3e}|^2 in the mu-e
conversion and mu-->3e decay rates, eqs. (36) and (49), respectively,
corrected; results in subsections 2.2 and 2.3 quantitatively changed,
qualitatively remain the same; figures 2, 3, 4 and 5 replace
Two-Higgs Leptonic Minimal Flavour Violation
We construct extensions of the Standard Model with two Higgs doublets, where
there are flavour changing neutral currents both in the quark and leptonic
sectors, with their strength fixed by the fermion mixing matrices and
. These models are an extension to the leptonic sector of the class
of models previously considered by Branco, Grimus and Lavoura, for the quark
sector. We consider both the cases of Dirac and Majorana neutrinos and identify
the minimal discrete symmetry required in order to implement the models in a
natural way.Comment: 25 pages. No figure
New insights into the neolithisation process in southwest Europe according to spatial density analysis from calibrated radiocarbon dates
The agricultural way of life spreads throughout Europe via two main routes: the Danube corridor and the Mediterranean basin. Current archaeological literature describes the arrival to the Western Mediterranean as a rapid process which involves both demic and cultural models, and in this regard, the dispersal movement has been investigated using mathematical models, where the key factors are time and space. In this work, we have created a compilation of all available radiocarbon dates for the whole of Iberia, in order to draw a chronological series of maps to illustrate temporal and spatial patterns in the neolithisation process. The maps were prepared by calculating the calibrated 14C date probability density curves, as a proxy to show the spatial dynamics of the last hunter-gatherers and first farmers. Several scholars have pointed out problems linked with the variability of samples, such as the overrepresentation of some sites, the degree of regional research, the nature of the dated samples and above all the archaeological context, but we are confident that the selected dates, after applying some filters and statistical protocols, constitute a good way to approach settlement spatial patterns in Iberia at the time of the neolithisation process
Prevalence and factors associated with poor performance in the 5âchair stand test: findings from the Cognitive Function and Ageing Study II and proposed Newcastle protocol for use in the assessment of sarcopenia
Background Poor performance in the 5âchair stand test (5âCST) indicates reduced lower limb muscle strength. The 5âCST has been recommended for use in the initial assessment of sarcopenia, the accelerated loss of muscle strength and mass. In order to facilitate the use of the 5âCST in sarcopenia assessment, our aims were to (i) describe the prevalence and factors associated with poor performance in the 5âCST, (ii) examine the relationship between the 5âCST and gait speed, and (iii) propose a protocol for using the 5âCST. Methods The populationâbased study Cognitive Function and Ageing Study II recruited people aged 65 years and over from defined geographical localities in Cambridgeshire, Newcastle, and Nottingham. The study collected data for assessment of functional ability during home visits, including the 5âCST and gait speed. We used multinomial logistic regression to assess the associations between factors including the SARCâF questionnaire and the category of 5âCST performance: fast (15 s), or unable, with slow/unable classed as poor performance. We reviewed previous studies on the protocol used to carry out the 5âCST. Results A total of 7190 participants aged 65+ from the three diverse localities of Cognitive Function and Ageing Study II were included (54.1% female). The proportion of those with poor performance in the 5âCST increased with age, from 34.3% at age 65â69 to 89.7% at age 90+. Factors independently associated with poor performance included positive responses to the SARCâF questionnaire, physical inactivity, depression, impaired cognition, and multimorbidity (all P < 0.005). Most people with poor performance also had slow gait speed (57.8%) or were unable to complete the gait speed test (18.4%). We found variation in the 5âCST protocol used, for example, timing until a participant stood up for the fifth time or until they sat down afterwards. Conclusions Poor performance in the 5âCST is increasingly common with age and is associated with a cluster of other factors that characterize risk for poor ageing such as physical inactivity, impaired cognition, and multimorbidity. We recommend a low threshold for performing the 5âCST in clinical settings and provide a protocol for its use
Enhanced Higgs Mediated Lepton Flavour Violating Processes in the Supersymmetric Inverse Seesaw Model
We study the impact of the inverse seesaw mechanism on several low-energy
flavour violating observables such as tau decaying to three muons in the
context of the Minimal Supersymmetric Standard Model. As a consequence of the
inverse seesaw, the contributions of the right-handed sneutrinos significantly
enhance the Higgs-mediated penguin diagrams. We find that different flavour
violating branching ratios can be enhanced by as much as two orders of
magnitude. We also comment on the impact of the Higgs-mediated processes on the
leptonic B-meson decays and on the Higgs flavour violating decays.Comment: 16 pages, 6 figures, version to appear in JHE
Relationships between heavy metal concentrations in three different body fluids and male reproductive parameters: a pilot study
<p>Abstract</p> <p>Background</p> <p>Animal studies have shown the reproductive toxicity of a number of heavy metals. Very few human observational studies have analyzed the relationship between male reproductive function and heavy metal concentrations in diverse biological fluids.</p> <p>Methods</p> <p>The current study assessed the associations between seminal and hormonal parameters and the concentration of the 3 most frequent heavy metal toxicants (lead, cadmium and mercury) in three different body fluids. Sixty one men attending infertility clinics that participated in a case-control study to explore the role of environmental toxins and lifestyles on male infertility were analyzed. Concentration of lead, cadmium and mercury were measured in blood and seminal plasma and whole blood using anodic stripping voltammetry and atomic absorption spectrophotometry. Serum samples were analyzed for follicle-stimulating hormone, luteinizing hormone and testosterone. Semen analyses were performed according to World Health Organization criteria. Mann-Whitney test and Spearman's rank correlations were used for unadjusted analyses. Multiple linear regression models were performed controlling for age, body mass index and number of cigarettes per day.</p> <p>Results</p> <p>There were no significant differences between cases and controls in the concentrations of heavy metals in any of the three body fluids. In multivariate analyses using all subjects no significant associations were found between serum hormone levels and metal concentrations. However there was a significant positive association between the percentage of immotile sperms and seminal plasma levels of lead and cadmium.</p> <p>Conclusions</p> <p>Our results suggest that the presence of lead and cadmium in the reproductive tract of men may be related to a moderate alteration of their seminal parameters.</p
Mice lacking endoglin in macrophages show an impaired immune response
24 p.-9 fig.-1 tab. Ojeda Fernåndez, Luisa et al.Endoglin is an auxiliary receptor for members of the TGF-β superfamily and plays an important role in the homeostasis of the vessel wall. Mutations in endoglin gene (ENG) or in the closely related TGF-β receptor type I ACVRL1/ALK1 are responsible for a rare dominant vascular dysplasia, the Hereditary Hemorrhagic Telangiectasia (HHT), or Rendu-OslerWeber syndrome. Endoglin is also expressed in human macrophages, but its role in macrophage function remains unknown. In this work, we show that endoglin expression is triggered during the monocyte-macrophage differentiation process, both in vitro and during the in vivo differentiation of blood monocytes recruited to foci of inflammation in wild-type C57BL/6 mice. To analyze the role of endoglin in macrophages in vivo, an endoglin myeloid lineage specific knock-out mouse line (Engfl/flLysMCre) was generated. These mice show a predisposition to develop spontaneous infections by opportunistic bacteria. Engfl/flLysMCre mice also display increased survival following LPS-induced peritonitis, suggesting a delayed immune response. Phagocytic activity is impaired in peritoneal macrophages, altering one of the main functions of macrophages which contributes to the initiation of the immune response. We also observed altered expression of TGF-β1 target genes in endoglin
deficient peritoneal macrophages. Overall, the altered immune activity of endoglin deficient macrophages could help to explain the higher rate of infectious diseases seen in HHT1 patients.This work was funded by: Ministerio de EconomĂa y Competitividad of Spain (SAF2011-23475 to LMB; SAF2013-43421-R and SAF2010-
19222 to CB.Peer reviewe
- âŚ