International Diversification: A Copula Approach

.Diversification; Copula; Correlation Complexity; Downside Risk; Systemic Risk

International Diversification: An Extreme Value Approach

.Diversification; Downside Risk; Correlation Complexity; Extreme Value; Systemic Risk

Self-normalized processes: exponential inequalities, moment bounds and iterated logarithm laws

Self-normalized processes arise naturally in statistical applications. Being unit free, they are not affected by scale changes. Moreover, self-normalization often eliminates or weakens moment assumptions. In this paper we present several exponential and moment inequalities, particularly those related to laws of the iterated logarithm, for self-normalized random variables including martingales. Tail probability bounds are also derived. For random variables B_t>0 and A_t, let Y_t(\lambda)=\exp{\lambda A_t-\lambda ^2B_t^2/2}. We develop inequalities for the moments of A_t/B_{t} or sup_{t\geq 0}A_t/{B_t(\log \log B_{t})^{1/2}} and variants thereof, when EY_t(\lambda )\leq 1 or when Y_t(\lambda) is a supermartingale, for all \lambda belonging to some interval. Our results are valid for a wide class of random processes including continuous martingales with A_t=M_t and B_t=\sqrt _t, and sums of conditionally symmetric variables d_i with A_t=\sum_{i=1}^td_i and B_t=\sqrt\sum_{i=1}^td_i^2. A sharp maximal inequality for conditionally symmetric random variables and for continuous local martingales with values in R^m, m\ge 1, is also established. Another development in this paper is a bounded law of the iterated logarithm for general adapted sequences that are centered at certain truncated conditional expectations and self-normalized by the square root of the sum of squares. The key ingredient in this development is a new exponential supermartingale involving \sum_{i=1}^td_i and \sum_{i=1}^td_i^2.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Probability (http://www.imstat.org/aop/) at http://dx.doi.org/10.1214/00911790400000039

Sharp Concentration Results for Heavy-Tailed Distributions

We obtain concentration and large deviation for the sums of independent and identically distributed random variables with heavy-tailed distributions. Our concentration results are concerned with random variables whose distributions satisfy $P(X>t) \leq {\rm e}^{- I(t)}$, where $I: \mathbb{R} \rightarrow \mathbb{R}$ is an increasing function and $I(t)/t \rightarrow \alpha \in [0, \infty)$ as $t \rightarrow \infty$. Our main theorem can not only recover some of the existing results, such as the concentration of the sum of subWeibull random variables, but it can also produce new results for the sum of random variables with heavier tails. We show that the concentration inequalities we obtain are sharp enough to offer large deviation results for the sums of independent random variables as well. Our analyses which are based on standard truncation arguments simplify, unify and generalize the existing results on the concentration and large deviation of heavy-tailed random variables.Comment: 16 page

Proposta de intervenção para melhoria do controle da pressão arterial em idosos hipertensos no território da equipe de saúde da família do Vila Betel em Teófilo Otoni - Minas Gerais

A Hipertensão Arterial está entre as doenças de maior prevalência e o não controle leva a um aumento do risco de eventos cardiovasculares fatais e não-fatais. Vários são os motivos que dificultam o controle e o tratamento da HAS, entre eles, a não adesão ao tratamento medicamentoso, o sedentarismo e alimentação inadequada são os mais expressivos. O objetivo do presente estudo é realizar uma proposta de intervenção para aumentar o controle da pressão arterial em idosos hipertensos, o âmbito de abrangência da Estratégia Saúde da Família (ESF) Vila Betel, no município de Teófilo Otoni - MG. A análise situacional da referida área, realizada através do método de estimativa rápida em banco de dados eletrônicos e entrevistas com atores chaves (profissionais de saúde e usuários), possibilitou a identificação do alto número de hipertensos sem controle da doença, como o principal problema de saúde da população adstrita, que foi priorizado, para a elaboração da proposta de intervenção, segundo o método de Planejamento Estratégico Situacional (PES). Após revisão bibliográfica nas principais bases de dados eletrônicas, chegou-se à elaboração de 3 projetos: "Hora Certa", "Pense, coma e mexa-se" e "Hipercontrole" que tem como finalidade a melhoria dos níveis pressóricos da população hipertensa. Este trabalho, se justifica pela viabilidade, facilidade e baixo custo para implantação, utilizando recursos humanos e materiais já existentes no atual contexto. Pode-se dizer que este é o início do um longo caminho a ser trilhado para a melhoria da qualidade de vida dessa populaçã

Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes

This is the peer reviewed version of the following article: Neumeier, M., Chakraborty, U., Schaarschmidt, D., de la Pena O'Shea, V., Perez¿Ruiz, R., & Jacobi von Wangelin, A. (2020). Combined photoredox and iron catalysis for the cyclotrimerization of alkynes. Angewandte Chemie International Edition, 59(32), 13473-13478, which has been published in final form at https://doi.org/10.1002/anie.202000907. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] Successful combinations of visible-light photocatalysis with metal catalysis have recently enabled the development of hitherto unknown chemical reactions. Dual mechanisms from merging metal-free photocatalysts and earth-abundant metal catalysts are still in their infancy. We report a photo-organo-iron-catalyzed cyclotrimerization of alkynes by photoredox activation of a ligand-free Fe catalyst. The reaction operates under very mild conditions (visible light, 20 degrees C, 1 h) with 1-2 mol % loading of the three catalysts (dye, amine, FeCl2).This work was supported by the Fonds der Chemischen Industrie (to M.N.) and the European Research Council (CoG 683150). We thank Luana Cardinale for technical support.Neumeier, M.; Chakraborty, U.; Schaarschmidt, D.; De La Pena O'shea, V.; Pérez-Ruiz, R.; Jacobi Von Wangelin, A. (2020). Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes. Angewandte Chemie International Edition. 59(32):13473-13478. https://doi.org/10.1002/anie.2020009071347313478593

Bringing Earth-Abundant Plasmonic Catalysis to Light : Gram-Scale Mechanochemical Synthesis and Tuning of Activity by Dual Excitation of Antenna and Reactor Sites

The localized surface plasmon resonance (LSPR) excitation in plasmonic nanoparticles (NPs) in the visible and near-infrared ranges is currently at the forefront of improving photocatalytic performances via plasmonic photocatalysis. One bottleneck of this field is that the NPs that often display the best optical properties in the visible and near-infrared ranges are based on expensive noble metals such as silver (Ag) and gold (Au). While earth-abundant plasmonic materials have been proposed together with catalytic metals in antenna-reactor systems, their performances remain limited by their optical properties. Importantly, the synthesis of plasmonic photocatalysts remains challenging in terms of scalability while often requiring several steps, high temperatures, and special conditions. Herein, we address these challenges by developing a one-pot, gram-scale, room-temperature synthesis of earth-abundant plasmonic photocatalysts while improving their activities beyond what has been dictated by the LSPR excitation of the plasmonic component. We describe the mechanochemical synthesis of earth-abundant plasmonic photocatalysts by using MoO3 (antenna) and Au (reactor) NPs as a proof-of-concept example and demonstrate that the dual plasmonic excitation of antenna and reactor sites enables the tuning of plasmonic photocatalytic performances toward the reductive coupling of nitrobenzene to azobenzene as a model reaction. In addition to providing a pathway to the facile and gramscale synthesis of plasmonic photocatalysts, the results reported herein may open pathways to improved activities in plasmonic catalysis.Peer reviewe