399 research outputs found
Lepton mass generation and family number violation mechanism in the model
Lepton family number violation processes arise in the model due to the presence of an extra neutral gauge boson, Z, with
family changing couplings, and due to the fact that this model demands the
existence of heavy exotic leptons. The mixing of the standard Z with Z and
the mixing of ordinary leptons with exotic ones induce together family changing
couplings on the Z and therefore nonvanishing rates for lepton family number
violation processes, such as , and . Additional contributions to the processes and
are induced from the mass generation mechanism. This last
type of contributions may compete with the above one, depending on the masses
of the scalars which participate in the diagrams which generate radiatively the
masses of the charged leptons. Using the experimental data we compute some
bounds for the mixings parameters and for the masses of the scalars.Comment: 12 pages, Latex, 7 figures. Accepted for publication in Int. Journ.
of Mod. Phys.
Quantum Interference and Contact Effects in the Thermoelectric Performance of Anthracene-Based Molecules
We report on the single-molecule electronic and thermoelectric properties of strategically chosen anthracene-based molecules with anchor groups capable of binding to noble metal substrates, such as gold and platinum. Specifically, we study the effect of different anchor groups, as well as quantum interference, on the electric conductance and the thermopower of gold/single-molecule/gold junctions and generally find good agreement between theory and experiments. All molecular junctions display transport characteristics consistent with coherent transport and a Fermi alignment approximately in the middle of the highest occupied molecular orbital/lowest unoccupied molecular orbital gap. Single-molecule results are in agreement with previously reported thin-film data, further supporting the notion that molecular design considerations may be translated from the single- to many-molecule devices. For combinations of anchor groups where one binds significantly more strongly to the electrodes than the other, the stronger anchor group appears to dominate the thermoelectric behavior of the molecular junction. For other combinations, the choice of electrode material can determine the sign and magnitude of the thermopower. This finding has important implications for the design of thermoelectric generator devices, where both n- and p-type conductors are required for thermoelectric current generation
Protease-activated receptor-2 (PAR2) in cardiovascular system.
Vascular system is constituted by a complex and articulate network, e.g. arteries, arterioles, venules and veins, that requires a high degree of coordination between different elemental cell types. Proteinase-activated receptors (PARs) constitute a recent described family of 7-transmembrane G protein-coupled receptors that are activated by proteolysis. In recent years several evidence have been accumulated for an involvement of this receptor in the response to endothelial injury in vitro and in vivo experimental settings suggesting a role for PAR2 in the pathophysiology of cardiovascular system. This review will deal with the role of PAR2 receptor in the cardiovascular system analyzing both in vivo and in vitro published data. In particular this review will deal with the role of this receptor in vascular reactivity, ischemia/reperfusion injury, coronary atherosclerotic lesions and angiogenesis
Cerebral cavernous malformations proteins inhibit Rho kinase to stabilize vascular integrity
Endothelial cellâcell junctions regulate vascular permeability, vasculogenesis, and angiogenesis. Familial cerebral cavernous malformations (CCMs) in humans result from mutations of CCM2 (malcavernin, OSM, MGC4607), PDCD10 (CCM3), or KRIT1 (CCM1), a Rap1 effector which stabilizes endothelial cellâcell junctions. Homozygous loss of KRIT1 or CCM2 produces lethal vascular phenotypes in mice and zebrafish. We report that the physical interaction of KRIT1 and CCM2 proteins is required for endothelial cellâcell junctional localization, and lack of either protein destabilizes barrier function by sustaining activity of RhoA and its effector Rho kinase (ROCK). Protein haploinsufficient Krit1+/â or Ccm2+/â mouse endothelial cells manifested increased monolayer permeability in vitro, and both Krit1+/â and Ccm2+/â mice exhibited increased vascular leak in vivo, reversible by fasudil, a ROCK inhibitor. Furthermore, we show that ROCK hyperactivity occurs in sporadic and familial human CCM endothelium as judged by increased phosphorylation of myosin light chain. These data establish that KRIT1âCCM2 interaction regulates vascular barrier function by suppressing Rho/ROCK signaling and that this pathway is dysregulated in human CCM endothelium, and they suggest that fasudil could ameliorate both CCM disease and vascular leak
Association of temporal factors and suicides in the United States, 2000â2004
The purpose of the study was to examine the association of temporal factors, in particular days of the week and seasons of the year and death from suicide in the United States.
Data were pooled from the Multiple Cause of Death Files. Hierarchical logistic regression models were fitted to all deaths occurring in 2000 through 2004 by suicide.
The incidence of suicide was significantly higher on Wednesdays, compared to Sunday. Specifically, individuals were 99% more likely to kill themselves on Wednesday than on Sunday. Suicides were more prevalent in the summer months, and they were less likely to occur in winter. The state suicide rate significantly elevated individual suicide risk. The results held even after controlling for the potentially confounding effects of socio-economic and demographic variables at both the individual and state levels.
It was concluded that the observed association between seasonality and suicide cannot be discounted as a mere coincidence. Future research ought to focus on integrating individual level data and contextual variables when testing for seasonality effects
Predictors of low cervical cancer screening among immigrant women in Ontario, Canada
<p>Abstract</p> <p>Background</p> <p>Disparities in cervical cancer screening are known to exist in Ontario, Canada for foreign-born women. The relative importance of various barriers to screening may vary across ethnic groups. This study aimed to determine how predictors of low cervical cancer screening, reflective of sociodemographics, the health care system, and migration, varied by region of origin for Ontario's immigrant women.</p> <p>Methods</p> <p>Using a validated billing code algorithm, we determined the proportion of women who were not screened during the three-year period of 2006-2008 among 455 864 identified immigrant women living in Ontario's urban centres. We created eight identical multivariate Poisson models, stratified by eight regions of origin for immigrant women. In these models, we adjusted for various sociodemographic, health care-related and migration-related variables. We then used the resulting adjusted relative risks to calculate population-attributable fractions for each variable by region of origin.</p> <p>Results</p> <p>Region of origin was not a significant source of effect modification for lack of recent cervical cancer screening. Certain variables were significantly associated with lack of screening across all or nearly all world regions. These consisted of not being in the 35-49 year age group, residence in the lowest-income neighbourhoods, not being in a primary care patient enrolment model, a provider from the same region, and not having a female provider. For all women, the highest population-attributable risk was seen for not having a female provider, with values ranging from 16.8% [95% CI 14.6-19.1%] among women from the Middle East and North Africa to 27.4% [95% CI 26.2-28.6%] for women from East Asia and the Pacific.</p> <p>Conclusions</p> <p>To increase screening rates across immigrant groups, efforts should be made to ensure that women have access to a regular source of primary care, and ideally access to a female health professional. Efforts should also be made to increase the enrolment of immigrant women in new primary care patient enrolment models.</p
Recommended from our members
Measuring Unethical Consumer Behavior Across Four Countries
The huge amounts spent on store security and crime prevention worldwide, not only costs international businesses, but also amounts to a hidden tax on those law-binding consumers who bear higher prices. Most previous research has focused on shoplifting and ignored many other ways in which consumers cheat businesses. Using a hybrid of both qualitative research and survey approaches in four countries, an index of 37 activities was developed to examine consumersâ unethical activities across UK, US, France, and Austria. The findings indicate that around three quarters of consumers in all four countries can be classified as heavy offenders for these minor cheats. The paper argues that government agencies, marketers, and retailers should adopt more pro-active preventative approaches, rather than reactive loss limitation measures to combat unethical behavior
- âŚ