On the mechanism of iodine oxide particle formation

The formation of atmospherically relevant iodine oxides IxO y (x = 1,...,3, y = 1,...,7) has been studied experimentally using time-of-flight mass spectrometry combined with a soft ionisation source, complemented with ab initio electronic structure calculations of ionisation potentials and bond energies at a high level of theory presented in detail in the accompanying paper (Galvez et al., 2013). For the first time, direct experimental evidence of the I2Oy (y = 1,...,5) molecules in the gas phase has been obtained. These chemical species are observed alongside their precursors (IO and OIO) in experiments where large amounts of aerosol are also generated. The measured relative concentrations of the I xOy molecules and their dependence on ozone concentration have been investigated by using chemical modelling and rate theory calculations. It is concluded that I2O4 is the most plausible candidate to initiate nucleation, while the contribution of I2O5 in the initial steps is likely to be marginal. The absence of large I 3Oy (y = 3,...,6) peaks in the mass spectra and the high stability of the I2O4-I2O4 dimer indicate that dimerisation of I2O4 is the key step in iodine oxide particle nucleation

A gas-to-particle conversion mechanism helps to explain atmospheric particle formation through clustering of iodine oxides

Emitted from the oceans, iodine-bearing molecules are ubiquitous in the atmosphere and a source of new atmospheric aerosol particles of potentially global significance. However, its inclusion in atmospheric models is hindered by a lack of understanding of the first steps of the photochemical gas-to-particle conversion mechanism. Our laboratory results show that under a high humidity and low HOx regime, the recently proposed nucleating molecule (iodic acid, HOIO2) does not form rapidly enough, and gas-to-particle conversion proceeds by clustering of iodine oxides (IxOy), albeit at slower rates than under dryer conditions. Moreover, we show experimentally that gas-phase HOIO2 is not necessary for the formation of HOIO2-containing particles. These insights help to explain new particle formation in the relatively dry polar regions and, more generally, provide for the first time a thermochemically feasible molecular mechanism from ocean iodine emissions to atmospheric particles that is currently missing in model calculations of aerosol radiative forcing

Traveling waves for a model of the Belousov-Zhabotinsky reaction

Following J.D. Murray, we consider a system of two differential equations that models traveling fronts in the Noyes-Field theory of the Belousov-Zhabotinsky (BZ) chemical reaction. We are also interested in the situation when the system incorporates a delay $h\geq 0$. As we show, the BZ system has a dual character: it is monostable when its key parameter $r \in (0,1]$ and it is bistable when $r >1$. For $h=0, r\not=1$, and for each admissible wave speed, we prove the uniqueness of monotone wavefronts. Next, a concept of regular super-solutions is introduced as a main tool for generating new comparison solutions for the BZ system. This allows to improve all previously known upper estimations for the minimal speed of propagation in the BZ system, independently whether it is monostable, bistable, delayed or not. Special attention is given to the critical case $r=1$ which to some extent resembles to the Zeldovich equation.Comment: 23 pages, to appear in the Journal of Differential Equation

Relaxing b\to s\gamma Constraints on the Supersymmetric Particle Mass Spectrum

We consider the radiative decay b \to s \gamma in a supersymmetric extension of the standard model of particle interactions, where the $b$-quark mass is entirely radiative in origin. This is accomplished by the presence of nonholomorphic soft supersymmetry breaking terms in the Lagrangian. As a result, the contributions to the b \to s \gamma amplitude from the charged Higgs boson and the charginos/neutralinos are suppressed by 1/\tan^2\beta and {\cal O}(\alpha/\alpha_s) respectively, allowing these particles to be lighter than in the usual supersymmetric model. Their radiatively generated couplings differ from the usual tree-level ones and change the collider phenomenology drastically. We also study how this scenario may be embedded into a larger framework, such as supersymmetric SU(5) grand unification.Comment: references added, version to be published in PL

Independent genomic polymorphisms in the PknH serine threonine kinase locus during evolution of the Mycobacterium tuberculosis Complex affect virulence and host preference

Species belonging to the Mycobacterium tuberculosis Complex (MTBC) show more than 99% genetic identity but exhibit distinct host preference and virulence. The molecular genetic changes that underly host specificity and infection phenotype within MTBC members have not been fully elucidated. Here, we analysed RD900 genomic region across MTBC members using whole genome sequences from 60 different MTBC strains so as to determine its role in the context of MTBC evolutionary history. The RD900 region comprises two homologous genes, pknH1 and pknH2, encoding a serine/threonine protein kinase PknH flanking the tbd2 gene. Our analysis revealed that RD900 has been independently lost in different MTBC lineages and different strains, resulting in the generation of a single pknH gene. Importantly, all the analysed M. bovis and M. caprae strains carry a conserved deletion within a proline rich-region of pknH, independent of the presence or absence of RD900. We hypothesized that deletion of pknH proline rich-region in M. bovis may affect PknH function, having a potential role in its virulence and evolutionary adaptation. To explore this hypothesis, we constructed two M. bovis ‘knock-in’ strains containing the M. tuberculosis pknH gene. Evaluation of their virulence phenotype in mice revealed a reduced virulence of both M. bovis knock-in strains compared to the wild type, suggesting that PknH plays an important role in the differential virulence phenotype of M. bovis vs M. tuberculosis

Natural R-Parity, \mu-term, and Fermion Mass Hierarchy From Discrete Gauge Symmetries

In the minimal supersymmetric Standard Model with seesaw neutrino masses we show how R-parity can emerge naturally as a discrete gauge symmetry. The same discrete symmetry explains the smallness of the \mu-term (the Higgsino mass parameter) via the Giudice--Masiero mechanism. The discrete gauge anomalies are cancelled by a discrete version of the Green--Schwarz mechanism. The simplest symmetry group is found to be Z_4 with a charge assignment that is compatible with grand unification. Several other Z_N gauge symmetries are found for N=10,12,18,36 etc, with some models employing discrete anomaly cancellation at higher Kac-Moody levels. Allowing for a flavor structure in Z_N, we show that the same gauge symmetry can also explain the observed hierarchy in the fermion masses and mixings.Comment: 22 pages, LaTe

Clinical factors associated with high glycemic variability defined by coefficient of variation in patients with type 2 diabetes

Antecedentes: La Variabilidad Glucémica Alta (VHG) ha convertirse en un predictor más fuerte de hipoglucemia. Sin embargo, aún se desconocen los factores clínicos asociados con el VHG. Objetivo:Determinar las variables clínicas que se asociaron con un coeficiente de variación (CV) superior al 36% evaluado mediante monitorización continua de glucosa (MCG) en un grupo de pacientes con diabetes mellitus. Métodos: Se evaluó una cohorte de pacientes con diabetes tipo 2 (T2D). Se evaluaron variables demográficas, HbA1c, tasa de filtración glomerular (TFG) y régimen de tratamiento. Se realizó un análisis bivariado, para evaluar la asociación entre la variable resultado (CV > 36%) y cada una de las variables independientes. Se construyó un modelo multivariado para evaluar las asociaciones después de controlar las variables de confusión. Resultados:Se analizaron los datos de MCG de 274 pacientes. CV> 36% estuvo presente en 56 pacientes (20,4%). En el análisis bivariado se incluyeron variables demográficas y clínicas, como tiempo desde el diagnóstico, antecedente de hipoglucemia, A1c, FG y tratamiento instaurado. En el análisis multivariante, FG 9% (OR 2,81; IC 1,05,7,51; p:0,04) y antecedentes de hipoglucemia (OR 2,09; IC 1,02, 4,32; p: 0,04) se asociaron con VHG. El tratamiento con iDPP4 (OR 0,39; IC 0,19, 0,82; p: 0,01) y AGLP1 (OR 0,08; IC 0,01, 0,68; p: 0,02) se asoció inversamente con la VG. Conclusión:Variables clínicas como FG 9% y antecedentes de hipoglucemia se asocian a un VG alto. Nuestros datos sugieren que el uso de tecnología y tratamientos capaces de reducir la variabilidad glucémica podría ser útil en esta población para reducir el riesgo de hipoglucemia y mejorar el control glucémico.Q3Background: High glycemic Variability (HGV) has become a stronger predictor of hypoglycemia. However, clinical factors associate with HGV still are unknown. Objective: To determine clinical variables that were associated with a coefficient of variation (CV) above 36% evaluated by continuous glucose monitoring (CGM) in a group of patients with diabetes mellitus. Methods: A cohort of patients with type 2 diabetes (T2D) was evaluated. Demographic variables, HbA1c, glomerular filtration rate (GFR) and treatment regimen were assessed. A bivariate analysis was performed, to evaluate the association between the outcome variable (CV> 36%) and each of the independent variables. A multivariate model was constructed to evaluate associations after controlling for confounding variables. Results: CGM data from 274 patients were analyzed. CV> 36% was present in 56 patients (20.4%). In the bivariate analysis, demographic and clinical variables were included, such as time since diagnosis, hypoglycemia history, A1c, GFR and treatment established. In the multivariate analysis, GFR 9% (OR 2.81; CI 1.05,7.51; p:0.04) and hypoglycemia history (OR 2.09; CI 1.02,4.32; p:0.04) were associated with HGV. Treatment with iDPP4 (OR 0.39; CI 0.19,0.82; p:0.01) and AGLP1 (OR 0.08; CI 0.01,0.68; p:0.02) was inversely associated with GV. Conclusion: Clinical variables such as GFR 9% and a history of hypoglycemia are associated with a high GV. Our data suggest that the use of technology and treatments able to reduce glycemic variability could be useful in this population to reduce the risk of hypoglycemia and to improve glycemic control.Revista Internacional - Indexad

Community-acquired pneumonia in hospitalised patients: changes in aetiology, clinical presentation, and severity outcomes in a 10-year period

Staphylococcus aureus; Mortality; VirologyStaphylococcus aureus; Mortalidad; VirologíaStaphylococcus aureus; Mortalitat; VirologiaBackground and objective Community-acquired pneumonia (CAP) is a frequent cause of hospitalisation. Several factors, such as pandemics, vaccines and globalisation may lead to changes in epidemiology, clinical presentation, and outcomes of CAP, which oblige to a constant actualisation. We performed this study to analyse how these factors have evolved over a 10-year period. Materials and methods Patients diagnosed with CAP for two 1-year periods that were 10 years apart (2007–2008 and 2017–2018) were included. We compared microbiological information, clinical data and evolutive outcomes in the two periods. A mortality analysis was performed. Results 1043 patients were included: 452 during the first period (2007- 2008), and 591 during the second period (2017–2018). Bacterial aetiology did not change during the 10-year period, besides a slight increase in Staphylococcus aureus (0.9% vs 2.9%, p = 0.026). There was a decline in the proportion of bacteraemia in the second period (14.8% vs 9.6%, p = 0.012). The incidence of complicated pleural effusion and septic shock declined too (6.4% vs 3.6%, p = 0.04 and 15.5% vs 6.3%, p < 0.001). Respiratory failure and Intensive care unit (ICU) admission were similar in both periods. Variables independently associated with mortality were age and septic shock. Influenza vaccine was a protective factor against mortality in the second period. Conclusions We have not found relevant differences in the bacterial aetiology of CAP over this 10-year period. There has been a decline in septic complications of CAP such as septic shock, bacteraemia, and complicated pleural effusion. Influenza vaccination is an important tool to reduce mortality

Testing Yukawa-unified SUSY during year 1 of LHC: the role of multiple b-jets, dileptons and missing E_T

We examine the prospects for testing SO(10) Yukawa-unified supersymmetric models during the first year of LHC running at \sqrt{s}= 7 TeV, assuming integrated luminosity values of 0.1 to 1 fb^-1. We consider two cases: the Higgs splitting (HS) and the D-term splitting (DR3) models. Each generically predicts light gluinos and heavy squarks, with an inverted scalar mass hierarchy. We hence expect large rates for gluino pair production followed by decays to final states with large b-jet multiplicity. For 0.2 fb^-1 of integrated luminosity, we find a 5 sigma discovery reach of m(gluino) ~ 400 GeV even if missing transverse energy, E_T^miss, is not a viable cut variable, by examining the multi-b-jet final state. A corroborating signal should stand out in the opposite-sign (OS) dimuon channel in the case of the HS model; the DR3 model will require higher integrated luminosity to yield a signal in the OS dimuon channel. This region may also be probed by the Tevatron with 5-10 fb^-1 of data, if a corresponding search in the multi-b+ E_T^miss channel is performed. With higher integrated luminosities of ~1 fb^-1, using E_T^miss plus a large multiplicity of b-jets, LHC should be able to discover Yukawa-unified SUSY with m(gluino) up to about 630 GeV. Thus, the year 1 LHC reach for Yukawa-unified SUSY should be enough to either claim a discovery of the gluino, or to very nearly rule out this class of models, since higher values of m(gluino) lead to rather poor Yukawa unification.Comment: 32 pages including 31 EPS figure