Controlled Microfabrication of High-Aspect-Ratio Structures in Silicon at the Highest Etching Rates: The Role of H2O2 in the Anodic Dissolution of Silicon in Acidic Electrolytes

In this work the authors report on the controlled electrochemical etching of high-aspect-ratio (from 5 to 100) structures in silicon at the highest etching rates (from 3 to 10 µm min−1) at room temperature. This allows silicon microfabrication entering a previously unattainable region where etching of high-aspect-ratio structures (beyond 10) at high etching rate (over 3 µm min−1) was prohibited for both commercial and research technologies. Addition of an oxidant, namely H2O2, to a standard aqueous hydrofluoric (HF) acid electrolyte is used to dramatically change the stoichiometry of the silicon dissolution process under anodic biasing without loss of etching control accuracy at the higher depths (up to 200 µm). The authors show that the presence of H2O2 reduces the valence of the dissolution process to 1, thus rendering the electrochemical etching more effective, and catalyzes the etching rate by opening a more efficient path for silicon dissolution with respect to the well-known Gerischer mechanism, thus increasing the etching speed at both shorter and higher depths

Desenvolvimento de revestimentos poliméricos para liberação controlada de ureia.

Entrada padronizada: RIBEIRO, C

A New Derivation of the CPT and Spin-Statistics Theorems in Non-Commutative Field Theories

We propose an alternative axiomatic description for non-commutative field theories (NCFT) based on some ideas by Soloviev to nonlocal quantum fields. The local commutativity axiom is replaced by the weaker condition that the fields commute at sufficiently large spatial separations, called asymptotic commutativity, formulated in terms of the theory of analytic functionals. The question of a possible violation of the CPT and Spin-Statistics theorems caused by nonlocality of the commutation relations $[\hat{x}_\mu,\hat{x}_\nu]=i\theta_{\mu\nu}$ is investigated. In spite of this inherent nonlocality, we show that the modification aforementioned is sufficient to ensure the validity of these theorems for NCFT. We restrict ourselves to the simplest model of a scalar field in the case of only space-space non-commutativity.Comment: The title is new, and the analysis in the manuscript has been made more precise. This revised version is to be published in J.Math.Phy

Methods and application in experimental pharmacology and drug discovery: 2021

Searching for new drugs is an expensive and time-consuming process, but it remains vital for the treatment of many old and new diseases. The availability of current advanced technologies has led to an acceleration of the drug discovery process, facilitating further development of personalized therapies. Sometimes, to obtain the desired therapeutic goals, the drug administration strategy can be of primary importance. Equally important, however, is the understanding of the complex mechanisms of action of new drugs on different cellular and molecular targets, both when the drugs are used alone and when they are administered in combination with other molecules

Carbon and nitrogen isotope fractionation of amino acids in an avian marine predator, the gentoo penguin (Pygoscelis papua)

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecology and Evolution 5 (2015): 1278–1290, doi:10.1002/ece3.1437.Compound-specific stable isotope analysis (CSIA) of amino acids (AA) has rapidly become a powerful tool in studies of food web architecture, resource use, and biogeochemical cycling. However, applications to avian ecology have been limited because no controlled studies have examined the patterns in AA isotope fractionation in birds. We conducted a controlled CSIA feeding experiment on an avian species, the gentoo penguin (Pygoscelis papua), to examine patterns in individual AA carbon and nitrogen stable isotope fractionation between diet (D) and consumer (C) (Δ13CC-D and Δ15NC-D, respectively). We found that essential AA δ13C values and source AA δ15N values in feathers showed minimal trophic fractionation between diet and consumer, providing independent but complimentary archival proxies for primary producers and nitrogen sources respectively, at the base of food webs supporting penguins. Variations in nonessential AA Δ13CC-D values reflected differences in macromolecule sources used for biosynthesis (e.g., protein vs. lipids) and provided a metric to assess resource utilization. The avian-specific nitrogen trophic discrimination factor (TDFGlu-Phe = 3.5 ± 0.4‰) that we calculated from the difference in trophic fractionation (Δ15NC-D) of glutamic acid and phenylalanine was significantly lower than the conventional literature value of 7.6‰. Trophic positions of five species of wild penguins calculated using a multi-TDFGlu-Phe equation with the avian-specific TDFGlu-Phe value from our experiment provided estimates that were more ecologically realistic than estimates using a single TDFGlu-Phe of 7.6‰ from the previous literature. Our results provide a quantitative, mechanistic framework for the use of CSIA in nonlethal, archival feathers to study the movement and foraging ecology of avian consumers.This research was funded by National Science Foundation Office of Polar Programs [grants ANT-0125098, ANT-0739575] and the 2013 Antarctic Science Bursaries

Fractional diffusions with time-varying coefficients

This paper is concerned with the fractionalized diffusion equations governing the law of the fractional Brownian motion $B_H(t)$. We obtain solutions of these equations which are probability laws extending that of $B_H(t)$. Our analysis is based on McBride fractional operators generalizing the hyper-Bessel operators $L$ and converting their fractional power $L^{\alpha}$ into Erd\'elyi--Kober fractional integrals. We study also probabilistic properties of the r.v.'s whose distributions satisfy space-time fractional equations involving Caputo and Riesz fractional derivatives. Some results emerging from the analysis of fractional equations with time-varying coefficients have the form of distributions of time-changed r.v.'s

Revisiting the link between body and agency: visual movement congruency enhances intentional binding but is not body-specific.

Embodiment and agency are key aspects of how we perceive ourselves that have typically been associated with independent mechanisms. Recent work, however, has suggested that these mechanisms are related. The sense of agency arises from recognising a causal influence on the external world. This influence is typically realised through bodily movements and thus the perception of the bodily self could also be crucial for agency. We investigated whether a key index of agency - intentional binding - was modulated by body-specific information. Participants judged the interval between pressing a button and a subsequent tone. We used virtual reality to manipulate two aspects of movement feedback. First, form: participants viewed a virtual hand or sphere. Second, movement congruency: the viewed object moved congruently or incongruently with the participant's hidden hand. Both factors, form and movement congruency, significantly influenced embodiment. However, only movement congruency influenced intentional binding. Binding was increased for congruent compared to incongruent movement feedback irrespective of form. This shows that the comparison between viewed and performed movements provides an important cue for agency, whereas body-specific visual form does not. We suggest that embodiment and agency mechanisms both depend on comparisons across sensorimotor signals but that they are influenced by distinct factors

Google haul out : Earth observation imagery and digital aerial surveys in coastal wildlife management and abundance estimation

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bioscience 67 (2017): 760–768, doi:10.1093/biosci/bix059.As the sampling frequency and resolution of Earth observation imagery increase, there are growing opportunities for novel applications in population monitoring. New methods are required to apply established analytical approaches to data collected from new observation platforms (e.g., satellites and unmanned aerial vehicles). Here, we present a method that estimates regional seasonal abundances for an understudied and growing population of gray seals (Halichoerus grypus) in southeastern Massachusetts, using opportunistic observations in Google Earth imagery. Abundance estimates are derived from digital aerial survey counts by adapting established correction-based analyses with telemetry behavioral observation to quantify survey biases. The result is a first regional understanding of gray seal abundance in the northeast US through opportunistic Earth observation imagery and repurposed animal telemetry data. As species observation data from Earth observation imagery become more ubiquitous, such methods provide a robust, adaptable, and cost-effective solution to monitoring animal colonies and understanding species abundances.We would like to thank generous support from International Fund for Animal Welfare, the Bureau of Ocean Energy, and the Oak Foundation for funding support for the telemetry devices