A combined SAXS/WAXS investigation of the phase behaviour of di-polyenoic membrane lipids

AbstractReal-time measurements of the SAXS/WAXS diffraction patterns of aqueous dispersions (1:1 wt/wt) of the di-polyenoic lipids di-18:2 PC, di-18:3 PC, di-18:2 PE and di-18:3 PE were made over the temperature range 10° to about −80°C. The results of these measurements were compared to similar measurements performed on the corresponding di-18:0 and di-18:1 derivatives. SAXS measurements of the temperature dependence of lamellar repeat distances show that the di-polyenoic lipids undergo broad second-order transitions between their gel and liquid-crystal lamellar phases spanning 30–40°C. The di-18:1 and di-18:0 derivatives, in contrast, undergo abrupt first-order transitions. The gel phases of the di-18:0 derivatives are characterised by two-component WAXS patterns with a sharp component close to 0.42 nm and a broader component at narrower spacings. On cooling, these lipids appear to undergo an initial transition to an Lβ, phase followed by a conversion to an Lc phase. The gel phases of the di-18:1 derivatives also show two-component patterns but with the sharp component centred closer to 0.44 nm. The di-polyenoic lipids, in contrast, are characterised by a single broad peak centred at a spacing of about 0.42 nm, close to that of conventional Lβ, phases. The changes in lamellar repeat distance accompanying the transitions in the di-monoenoic and di-polyenoic lipids, all of which occur in the frozen state, are very similar, indicating that the acyl chains of the polyenoic lipids are close to their maximum extension in the gel state. The WAXS patterns of the polyenoic lipids suggest that the saturated upper parts of the acyl chains are packed on a regular hexagonal lattice while their polyunsaturated termini remain relatively disordered

A probabilistic model for gene content evolution with duplication, loss, and horizontal transfer

We introduce a Markov model for the evolution of a gene family along a phylogeny. The model includes parameters for the rates of horizontal gene transfer, gene duplication, and gene loss, in addition to branch lengths in the phylogeny. The likelihood for the changes in the size of a gene family across different organisms can be calculated in O(N+hM^2) time and O(N+M^2) space, where N is the number of organisms, $h$ is the height of the phylogeny, and M is the sum of family sizes. We apply the model to the evolution of gene content in Preoteobacteria using the gene families in the COG (Clusters of Orthologous Groups) database

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

Simulating the Allocation of Organs for Transplantation

The demand for donated organs greatly exceeds supply and many candidates die awaiting transplantation. Policies for allocating deceased donor organs may address equity of access and medical efficacy, but typically must be implemented with incomplete information. Simulation-based analysis can inform the policy process by predicting the likely effects of alternative policies on a wide variety of outcomes of interest. This paper describes a family of simulations developed by the US Scientific Registry of Transplant Recipients and initial experience in the application of one member of this family, the Liver Simulated Allocation Model (LSAM).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45816/1/10729_2004_Article_5277541.pd

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Freqüência de infecção por Toxocara em crianças atendidas em serviço público de Maringá, sul do Brasil

The lack of specific laboratorial diagnosis methods and precise symptoms makes the toxocariasis a neglected disease in Public Health Services. This study aims to determine the frequency of Toxocara spp. infection in children attended by the Health Public Service of Hospital Municipal de Maringá, South Brazil. To evaluate the association of epidemiological and clinical data, an observational and cross-section study was carried out. From 14,690 attended children/year aged from seven month to 12 years old, 450 serum samples were randomly collected from September/2004 to September/2005. A questionnaire was used to evaluate epidemiological, clinical and hematological data. An ELISA using Toxocara canis larval excretory-secretory products as antigen detected 130 (28.8%) positive sera, mainly between children from seven month to five years old (p = 0.0016). Significant correlation was observed between positive serology for Toxocara, and frequent playing in sandbox at school or daycare center (p = 0.011) and the presence of a cat at home (p = 0.056). From the families, 50% were dog owners which exposed soil backyards. Eosinophilia (p = 0.776), and signs and symptoms analyzed (fever p = 0.992, pneumonia p = 0.289, cold-like symptoms p = 0.277, cough p = 0.783, gastrointestinal problems p = 0.877, migraine p = 0.979, abdominal pain p = 0.965, joint pain p = 0.686 and skin rash p = 0.105) could not be related to the presence of anti-Toxocara antibodies. Therefore, two asthmatics children showed titles of 1:10,240 and accentuated eosinophilia (p = 0.0001). The authors emphasize the needs of prevention activities.A falta de métodos de diagnóstico laboratorial específico e sintomas específicos fazem da toxocaríase uma doença negligenciada nos serviços públicos de saúde. Este estudo teve por objetivo determinar a freqüência de infecção por Toxocara spp. em crianças atendidas no serviço público do Hospital Municipal de Maringá, sul do Brasil, e avaliar a associação com dados epidemiológicos e clínicos, em estudo observacional e transversal. De 14.690 crianças/ano atendidas, com idade entre sete meses a 12 anos, foram coletados 450 soros de setembro/2004 a setembro/2005. Um questionário foi utilizado para avaliar dados epidemiológicos, clínicos e hematológicos. Pelo teste ELISA, com antígeno de excreção/secreção de larvas de Toxocara canis, detectou-se 130 (28,8%) soros positivos, principalmente em crianças entre sete meses e cinco anos (p = 0,0016). Houve significante correlação entre sorologia positiva para Toxocara e freqüente recreação das crianças em caixas de areia da escola ou pré escola (p = 0,011) e presença do gato no domicilio (p = 0,056). Das famílias dessas crianças, 50% possuíam cachorros e o quintal com solo exposto. Eosinofilia (p = 0,776), sinais e sintomas (febre p = 0,992, pneumonia p = 0,289, resfriado p = 0,277, tosse p = 0,783, problema gastrointestinal p = 0877, dor de cabeça p = 0,979, dor abdominal p = 0,965, dores articulares p = 0,686, urticária p = 0,105) não se correlacionaram com a soropositividade. Todavia, duas crianças asmáticas apresentaram títulos de 1:10.240 (>; 1:320) e acentuada eosinofilia (p = 0.0001). Os autores enfatizam a necessidade de atividades preventivas