Probing the mechanism of EWSB with a rho parameter defined in terms of Higgs couplings

A definition of the rho parameter based on the Higgs couplings with the gauge bosons, rho_h= g_{hWW}}/c^2_W g_{hZZ}, is proposed as a new probe into the origin of the mechanism of electroweak symmetry breaking. While $\rho_h=1$ holds in the SM, deviations from one are predicted in models with extended Higgs sector. We derive a general expresion of rho_h for a model with arbitrary Higgs multiplets, and discuss its size within the context of specific models with Higgs triplets, including the ``Little Higgs'' models recently proposed. We find the even for Higgs models that incorporate the custodial symmetry to make rho=1, one could have rho_h\neq 1, which could be tested at the level of a few percent, with the precision Higgs meassurements expected at the NLC.Comment: 12 pages, 2 figure

Microstructural white matter changes in metabolic syndrome: A diffusion tensor imaging study

BACKGROUND: Although metabolic syndrome is associated with cardiovascular disease and stroke, limited information is available on specific brain damage in patients with this syndrome. We investigated the relationship of the syndrome with white matter (WM) alteration using a voxel-based approach with diffusion tensor imaging (DTI). METHODS: We compared fractional anisotropy (FA) and apparent diffusion coefficient (ADC) measurements of DTI in 19 patients with metabolic syndrome aged between 50 and 80 years and 19 age-matched controls without any vascular risk factors for the syndrome. RESULTS: Patients with metabolic syndrome showed an anterior-posterior pattern of deterioration in WM with reduced FA and increased ADC values compared with controls. WM changes were not related to any isolated vascular risk factor. CONCLUSION: Although the mechanism of this damage is not clear, the results indicate microstructural white matter alterations in patients with metabolic syndrome, mainly involving the frontal lobe

Cargo sorting to lysosome-related organelles regulates siRNA-mediated gene silencing

The activity of siRNAs in gene silencing is regulated by protein complexes that sort cargo to lysosome-related organelles

Democracia en el Estado de México: fortalezas y debilidades

En toda interacción humana puede estar presente el poder. Por tanto, todas las formas de interacción humana son susceptibles de catalogarse como democráticas o como autoritarias (e incluso híbridas, cuando conjugan elementos democráticos y autoritarios). En la interacción democrática o bien está ausente el poder o bien éste es ejercido con tolerancia y con apego a normas preestablecidas. En la interacción autoritaria prevalece la intolerancia, la arbitrariedad y la violencia

Family-wide characterization of the DENN domain Rab GDP-GTP exchange factors

Target or substrate Rab GTPases are identified for 17 proteins with DENN domains

Iron Deficiency Increases Growth and Nitrogen-Fixation Rates of Phosphorus-Deficient Marine Cyanobacteria

Marine dinitrogen (N2)-fixing cyanobacteria have large impacts on global biogeochemistry as they fix carbon dioxide (CO2) and fertilize oligotrophic ocean waters with new nitrogen. Iron (Fe) and phosphorus (P) are the two most important limiting nutrients for marine biological N2 fixation, and their availabilities vary between major ocean basins and regions. A long-standing question concerns the ability of two globally dominant N2-fixing cyanobacteria, unicellular Crocosphaera and filamentous Trichodesmium, to maintain relatively high N2-fixation rates in these regimes where both Fe and P are typically scarce. We show that under P-deficient conditions, cultures of these two cyanobacteria are able to grow and fix N2 faster when Fe deficient than when Fe replete. In addition, growth affinities relative to P increase while minimum concentrations of P that support growth decrease at low Fe concentrations. In Crocosphaera, this effect is accompanied by a reduction in cell sizes and elemental quotas. Relatively high growth rates of these two biogeochemically critical cyanobacteria in low-P, low-Fe environments such as those that characterize much of the oligotrophic ocean challenge the common assumption that low Fe levels can have only negative effects on marine primary producers. The closely interdependent influence of Fe and P on N2-fixing cyanobacteria suggests that even subtle shifts in their supply ratio in the past, present and future oceans could have large consequences for global carbon and nitrogen cycles

Birth Weight and Adult IQ, but Not Anxious-Depressive Psychopathology, Are Associated with Cortical Surface Area: A Study in Twins

BACKGROUND: Previous research suggests that low birth weight (BW) induces reduced brain cortical surface area (SA) which would persist until at least early adulthood. Moreover, low BW has been linked to psychiatric disorders such as depression and psychological distress, and to altered neurocognitive profiles. AIMS: We present novel findings obtained by analysing high-resolution structural MRI scans of 48 twins; specifically, we aimed: i) to test the BW-SA association in a middle-aged adult sample; and ii) to assess whether either depression/anxiety disorders or intellectual quotient (IQ) influence the BW-SA link, using a monozygotic (MZ) twin design to separate environmental and genetic effects. RESULTS: Both lower BW and decreased IQ were associated with smaller total and regional cortical SA in adulthood. Within a twin pair, lower BW was related to smaller total cortical and regional SA. In contrast, MZ twin differences in SA were not related to differences in either IQ or depression/anxiety disorders. CONCLUSION: The present study supports findings indicating that i) BW has a long-lasting effect on cortical SA, where some familial and environmental influences alter both foetal growth and brain morphology; ii) uniquely environmental factors affecting BW also alter SA; iii) higher IQ correlates with larger SA; and iv) these effects are not modified by internalizing psychopathology.This work was supported by the Spanish SAF2008-05674, European Twins Study Network on Schizophrenia Research Training Network (grant number EUTwinsS; MRTN-CT-2006-035987), the Catalan 2014SGR1636 and the PIM2010-ERN- 00642 in frame of ERA-NET NEURON. A. Córdova- Palomera was funded by The National Council for Science and Technology (CONACyT, Mexico). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript