Controlling the anisotropic self-assembly of polybutadiene-grafted silica nanoparticles by tuning three-body interaction forces

Recently, the significant improvements in polymer composites properties have been mainly attributed to the ability of filler nanoparticles (NPs) to self-assemble into highly anisotropic self-assembled structures. In this work, we investigate the self-assembly of core–shell NPs composed of a silica core grafted with polybutadiene (PB) chains, generating the so-called ‘‘hairy’’ NPs (HNPs), immersed in tetrahydrofuran solvent. While uncoated silica beads aggregate forming uniform compact structures, the presence of a PB shell affects the silica NPs organization to the point that by increasing the polymer density at the corona, they tend to self-assemble into linear chain-like structures. To reproduce the experimental observations, we propose a theoretical model for the two-body that considers the van der Waals attractive energy together with the polymer-induced repulsive steric contribution and includes an additional three-body interaction term. This term arises due to the anisotropic distribution of PB, which increases their concentration near the NPs contact region. The resulting steric repulsion experienced by a third NP approaching the dimer prevents its binding close to the dimer bond and favors the growth of chain-like structures. We find good agreement between the simulated and experimental self-assembled superstructures, confirming that this three-body steric repulsion plays a key role in determining the cluster morphology of these core–shell NPs. The model also shows that further increasing the grafting density leads to low-density gel-like open structures.PirelliMilano Bicocca UniversityJunta de Andalucia European Regional Development Fund -Consejeria de Conocimiento, Investigacion y Universidad, Junta de Andalucia PY20-00241 A-FQM90-UGR20Consejo Nacional de Ciencia y Tecnologia (CONACyT) A1-S-919

Some Interesting Results About Behaviour of Granular Media

This study represents an attempt to clarify some anomalous behaviour found in alluvional terrains when subjected to an earthquake. Our approach to the study of granular media has been bibliographic and experimental. Despite many studies carried on this topic, this behaviour is still little understood because of the complex nature of granular media. The goal to the experimental research was at least to confirm the „anomalous“ behaviour reported in previous studies (e.g., chain of force, not-uniform distribution of pressure, etc.). In particular, this study is focused on pressure distributions and their quantification with respect to the pure granular media, and especially refers to the behaviour of natural deposits, which are intermediate between granular and cohesive media

Streamlined Variational Inference for Linear Mixed Models with Crossed Random Effects

We derive streamlined mean field variational Bayes algorithms for fitting linear mixed models with crossed random effects. In the most general situation, where the dimensions of the crossed groups are arbitrarily large, streamlining is hindered by lack of sparseness in the underlying least squares system. Because of this fact we also consider a hierarchy of relaxations of the mean field product restriction. The least stringent product restriction delivers a high degree of inferential accuracy. However, this accuracy must be mitigated against its higher storage and computing demands. Faster sparse storage and computing alternatives are also provided, but come with the price of diminished inferential accuracy. This article provides full algorithmic details of three variational inference strategies, presents detailed empirical results on their pros and cons and, thus, guides the users on their choice of variational inference approach depending on the problem size and computing resources

Alcohol drinking and head and neck cancer risk: The joint effect of intensity and duration

BACKGROUND: Alcohol is a well-established risk factor for head and neck cancer (HNC). This study aims to explore the effect of alcohol intensity and duration, as joint continuous exposures, on HNC risk. METHODS: Data from 26 case-control studies in the INHANCE Consortium were used, including never and current drinkers who drunk ≤10 drinks/day for ≤54 years (24234 controls, 4085 oral cavity, 3359 oropharyngeal, 983 hypopharyngeal and 3340 laryngeal cancers). The dose-response relationship between the risk and the joint exposure to drinking intensity and duration was investigated through bivariate regression spline models, adjusting for potential confounders, including tobacco smoking. RESULTS: For all subsites, cancer risk steeply increased with increasing drinks/day, with no appreciable threshold effect at lower intensities. For each intensity level, the risk of oral cavity, hypopharyngeal and laryngeal cancers did not vary according to years of drinking, suggesting no effect of duration. For oropharyngeal cancer, the risk increased with durations up to 28 years, flattening thereafter. The risk peaked at the higher levels of intensity and duration for all subsites (odds ratio = 7.95 for oral cavity, 12.86 for oropharynx, 24.96 for hypopharynx and 6.60 for larynx). CONCLUSIONS: Present results further encourage the reduction of alcohol intensity to mitigate HNC risk

Some developments in semiparametric and cross-classified multilevel models

Our work has developed from a real epidemiological problem. The carcinogenic effect of cigarette smoking on head and neck cancer has been extensively studied in the literature highlighting a non linear dose-response relationship. Recently, the use of linear regression splines, within semiparametric models framework, has allowed an improvement in the evaluation of the association between smoking habits and head and neck cancer. Our work focuses on the development of a methodology able to improve several aspects of the estimation of the aforementioned relationship. In particular, the approximation of the spline function, represented by truncated linear basis, has been refined by addressing the problem of estimating two key quantities for the definition of a spline function: the number and position of the knots. The proposed methodology uses a Bayesian approach. We then focused on developing a streamlined methodology applicable to generalised linear models for cross-classified data. In particular, the steps necessary to calculate the covariance matrix are optimised with respect to one of the two random effects, allowing a computational gain both in terms of time and memory usage. The proposed algorithms are applied in the context of the inferential variational methods in detail to the mean field variational Bayes

Effect of Physical Exercise on the Release of Microparticles with Angiogenic Potential

Cellular communication has a fundamental role in both human physiological and pathological states and various mechanisms are involved in the crosstalk between organs. Among these, microparticles (MPs) have an important involvement. MPs are a subtype of extracellular vesicles produced by a variety of cells following activation or apoptosis. They are normally present in physiological conditions, but their concentration varies in pathological states such as cardiovascular disease, diabetes mellitus, or cancer. Acute and chronic physical exercise are able to modify MPs amounts as well. Among various actions, exercise-responsive MPs affect angiogenesis, the process through which new blood vessels grow from pre-existing vessels. Usually, the neo vascular growth has functional role; but an aberrant neovascularization accompanies several oncogenic, ischemic, or inflammatory diseases. In addition, angiogenesis is one of the key adaptations to physical exercise and training. In the present review, we report evidence regarding the effect of various typologies of exercise on circulating MPs that are able to affect angiogenesis

A responsabilidade civil e administrativa pelo fornecimento de água : a crise hídrica paulista sob a ótica do Tribunal de Justiça de São Paulo

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Direito, 2019.O presente trabalho tem como objetivo analisar as decisões prolatadas pelo Tribunal de Justiça do Estado de São Paulo durante a crise hídrica vivida pelo estado entre os anos de 2014 e 2016, buscando compreender de que maneira os julgadores abordaram a questão da responsabilidade civil e administrativa pelos danos sofridos pela população. Assim, por meio de pesquisa bibliográfica e jurisprudencial, será realizada uma abordagem expositiva e conceitual acerca da prestação de serviços públicos de fornecimento de água por meio de concessão, identificando como a responsabilidade se aplica a eles. Em seguida serão feitas críticas às decisões estudadas, apontando, também, omissões de elementos imprescindíveis em um julgado inserido no contexto de uma crise hídrica. Por fim, será apresentada uma interpretação jurídica alternativa levando em consideração as críticas apontadas até então, com o objetivo de promover uma melhor gestão dos recursos hídricos através da responsabilização da cadeia de agentes envolvidos. A relevância do tema tem ligação direta com o papel social do Poder Judiciário na prevenção de novas situações de crise hídrica como as vividas pela Região Metropolitana de São Paulo.The present study aims to analyze the decisions rendered by the Court of Justice of the State of São Paulo during the water crisis experienced by the state between 2014 and 2016, seeking to understand how the judges addressed the issue of civil and administrative liability by damage suffered by the population. Through a bibliographical and jurisprudential research will be carried out a simple and conceptual approach about the provision of public water supply services through concession, identifying how the responsibility applies to them. Next, criticisms will be made on the decisions studied, pointing out also omissions of essential elements in a judgment inserted in the context of a water crisis. Finally, an alternative legal interpretation will be presented, taking into account the criticisms pointed out so far, in order to promote a better management of water resources through the accountability of the chain of agents involved. The relevance of this issue has a direct link with the social role of the Judiciary in the prevention of new situations of water crisis such as those experienced by the Metropolitan Region of São Paulo

Gravitational wave burst vetoes in the LIGO S2 and S3 data analyses

The LIGO detectors collected about 4 months of data in 2003-2004 during two science runs, S2 and S3. Several environmental and auxiliary channels that monitor the instruments' physical environment and overall interferometric operation were analyzed in order to establish the quality of the data as well as the presence of transients of non-astrophysical origin. This analysis allowed better understanding of the noise character of the instruments and the establishment of correlations between transients in these channels and the one recording the gravitational wave strain. In this way vetoes for spurious burst were identified. We present the methodology we followed in this analysis and the results from the S2 and S3 veto analysis within the context of the search for gravitational wave bursts.Comment: 9 pages, 4 figures, submitted to Classical and Quantum Gravity for the special issue of the GWDAW9 Proceeding

Signal Alignment Problems on Multi-element X-Ray Fluorescence Detectors

X-ray fluorescence (XRF) is a spectroscopic technique with applications in several fields, such as biology, food science and forensics. Often setups have multi-element detectors in order to improve the signal-to-noise ratio. The relative set of produced spectra have to be aligned to a reference spectrum, in a procedure that is referred to as energy calibration, which is necessary for the fitting. Automated methods fail and a manual procedure is typically employed instead. In this paper, we discuss the signal alignment problem of such systems and we illustrate the preliminary results of a new automated method for linear XRF spectra alignment, which potentially can be used also for other time-series like data