Mathematical modeling of Zika disease in pregnant women and newborns with microcephaly in Brazil

We propose a new mathematical model for the spread of Zika virus. Special attention is paid to the transmission of microcephaly. Numerical simulations show the accuracy of the model with respect to the Zika outbreak occurred in Brazil.Comment: This is a preprint of a paper whose final and definite form is with 'Mathematical Methods in the Applied Sciences', ISSN 0170-4214. Submitted Aug 10, 2017; Revised Nov 13, 2017; accepted for publication Nov 14, 201

Ebola Model and Optimal Control with Vaccination Constraints

The Ebola virus disease is a severe viral haemorrhagic fever syndrome caused by Ebola virus. This disease is transmitted by direct contact with the body fluids of an infected person and objects contaminated with virus or infected animals, with a death rate close to 90% in humans. Recently, some mathematical models have been presented to analyse the spread of the 2014 Ebola outbreak in West Africa. In this paper, we introduce vaccination of the susceptible population with the aim of controlling the spread of the disease and analyse two optimal control problems related with the transmission of Ebola disease with vaccination. Firstly, we consider the case where the total number of available vaccines in a fixed period of time is limited. Secondly, we analyse the situation where there is a limited supply of vaccines at each instant of time for a fixed interval of time. The optimal control problems have been solved analytically. Finally, we have performed a number of numerical simulations in order to compare the models with vaccination and the model without vaccination, which has recently been shown to fit the real data. Three vaccination scenarios have been considered for our numerical simulations, namely: unlimited supply of vaccines; limited total number of vaccines; and limited supply of vaccines at each instant of time.Comment: This is a preprint of a paper whose final and definite form is with 'Journal of Industrial and Management Optimization' (JIMO), ISSN 1547-5816 (print), ISSN 1553-166X (online). Submitted February 2016; revised November 2016; accepted for publication March 201

Localized Faraday patterns under heterogeneous parametric excitation

Faraday waves are a classic example of a system in which an extended pattern emerges under spatially uniform forcing. Motivated by systems in which uniform excitation is not plausible, we study both experimentally and theoretically the effect of heterogeneous forcing on Faraday waves. Our experiments show that vibrations restricted to finite regions lead to the formation of localized subharmonic wave patterns and change the onset of the instability. The prototype model used for the theoretical calculations is the parametrically driven and damped nonlinear Schr\"odinger equation, which is known to describe well Faraday-instability regimes. For an energy injection with a Gaussian spatial profile, we show that the evolution of the envelope of the wave pattern can be reduced to a Weber-equation eigenvalue problem. Our theoretical results provide very good predictions of our experimental observations provided that the decay length scale of the Gaussian profile is much larger than the pattern wavelength.Comment: 10 pages, 9 figures, Accepte

Dynamics of Serial Manipulators using Dual Quaternion Algebra

This paper presents two approaches to obtain the dynamical equations of serial manipulators using dual quaternion algebra. The first one is based on the recursive Newton-Euler formulation and uses twists and wrenches instead of 3D vectors, which simplifies the classic procedure by removing the necessity of exhaustive geometrical analyses since wrenches and twists are propagated through high-level algebraic operations. Furthermore, the proposed formulation works for arbitrary types of joints and does not impose any particular convention for the propagation of twists. The second approach, based on Gauss's Principle of Least Constraint (GPLC), takes into account elements of the dual quaternion algebra and provides a linear relationship between twists derivatives and joint accelerations, which can be particularly useful in robot control. Differently from other approaches based on the GPLC, which have representational singularities or require constraints, our method does not have those drawbacks. We present a thorough methodology to obtain the computational cost of both algorithms and compared them with their classic counterparts. Although our current formulations are more computationally expensive, they are more general than their counterparts in the state of the art. Simulation results showed that both methods are as accurate as the classic recursive Newton-Euler algorithm.Comment: Submitted for publication (currently under review

Exploring endolysin-loaded liposomes for a transtympanic treatment of S. pneumoniae otitis media

Otitis media, the main reason for which antibiotics are prescribed in childhood, is often caused by Streptococcus pneumoniae. The exogenous use of recombinantly produced endolysins, peptidoglycan hydrolases encoded by bacteriophages at the end of their lytic cycle, have been shown to be very effective against this pathogen. To increase bioavailability, and consequently reduce the probability of a recurrent or chronic infection, endolysins could be applied topically in the ear. However, delivery systems with permeation enhancing characteristics are needed to surpass the barrier provided by the tympanic membrane, which separates the ear canal from the middle ear. Therefore, this work aimed to develop a novel delivery system for a transtympanic treatment of pneumococcal otitis media using endolysins. The MSlys endolysin was encapsulated into deformable liposomes composed of L-alpha-lecithin and sodium cholate (L:SC:MSlys) or PEG2000 PE (L:PEG:MSlys) with a efficiency of approximately 35% in average, being released in a controlled manner. Liposomes loaded with MSlys showed no cytotoxicity against keratinocyte and fibroblast cell lines. Moreover, MSlys-loaded liposomes interacted with S. pneumoniae cells, being able to significantly reduce planktonic and biofilm cells. Transtympanic permeation studies demonstrated that PEGylated liposomes significantly enhanced the transport of MSlys through human tympanic membranes in an ex vivo model, showing antipneumococcal effect after 2 hours. Nevertheless, degradation of MSlys occurred during extended incubation at 37 ºC, which affected its effectiveness. In conclusion, endolysin-loaded liposomes are a promising approach for transtympanic treatment of otitis media caused by S. pneumoniae. Nevertheless, further optimization is required in order to increase effectiveness.info:eu-repo/semantics/publishedVersio

Liposomes loaded with the pneumococcal endolysin MSlys: From in vitro characterization to ex vivo permeation across the tympanic membrane

Introduction: The increasing antibiotic resistance triggered interest in novel antimicrobials as well as delivery systems that allow a topical and targeted delivery. However, biological barriers, such as the skin or the tympanic membrane (TM), may hinder the success of the therapy. Drug permeation has been extensively studied in the context of transdermal delivery, but only recently started to be explored for transtympanic applications. Ex vivo Franz diffusion cell permeation tests have been used and validated for the permeation of compounds through the skin prior to in vivo studies, but their exploitation for transtympanic delivery is limited. Endolysins, peptidoglycan hydrolases derived from bacterial viruses, are attractive antimicrobials, with promising action against the otitis media pathogen Streptococcus pneumoniae. Liposomal systems, such as transfersomes or PEGylated liposomes, have been shown to enhance drug permeation across the TM. Here, we describe the in vitro characterization of the endolysin-loaded liposomal carriers as well as their ex vivo permeation through TMs. Objectives: The main objective was to develop a delivery system containing an endolysin for a targeted transtympanic treatment of otitis media. To achieve this, it was necessary: i) to encapsulate the endolysin into liposomes for a controlled delivery; and ii) to evaluate the transtympanic permeation ability of the formulations. Materials and Methods: Liposomes composed of 4 mM of L-alpha-lecithin and sodium cholate (5:1) (L:SC) or L-alpha-lecithin and PEG2000 PE (10:1) (L:PEG) loaded with the MSlys endolysin were prepared. The size, polydispersity index (PDI), zeta potential, stability, deformability, encapsulation efficiency, and in vitro MSlys release were determined. The cytotoxicity against fibroblasts and keratinocytes and the efficacy against pneumococcal planktonic and biofilm cells were also evaluated in vitro. Permeation studies were performed in Franz diffusion cells using porcine skin, sheep TMs, and cadaveric human TMs. The amount of MSlys permeated and its antipneumococcal activity were evaluated, and the protein integrity was analyzed by SDS-PAGE. Results and Discussion: The MSlys endolysin was encapsulated into liposomes, with an average efficiency of about 35%. Liposomes with ca. 100 nm and relatively low PDI were produced, with L:PEG formulations being smaller and less polydisperse than L:SC. Both characteristics remained stable for one year at 4 C. Liposomes were shown to be deformable and to provide a controlled release of MSlys over time following a first-order kinetics. No cytotoxicity was observed. Endolysin-loaded liposomes interacted with S. pneumoniae cells, reducing both planktonic and biofilm cultures. The potential of L:PEG over L:SC formulations to transport MSlys was demonstrated in preliminary transdermal assays. The permeation of MSlys across the TMs was enhanced when loaded in PEGylated liposomes. Samples were shown to significantly reduce pneumococcal cells after 2 h of permeation through the human TM. Nonetheless, loss of antipneumococcal activity after 4 h of permeation and protein hydrolysis at 48 and 72 h were observed. Conclusions: This work reports the delivery of an endolysin through an intact TM using liposomes. However, further optimization is needed to expand the overall therapeutic efficacy of this strategy for use in otitis media.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit, the Wyss Institute for Biologically Inspired Engineering and from NIH NIDCD K08-DC018575 grant. MDS acknowledges the FCT grants SFRH/BD/128825/2017 and COVID/BD/152363/2022, and SS acknowledges funding by FCT through the individual scientific employment program contract (2020.03171.CEECIND).info:eu-repo/semantics/publishedVersio

Fiddler crabs and their above-ground sedimentary structures: a review

Fiddler crabs are abundant, semi-terrestrial crustaceans inhabiting tropical, subtropical and warm temperate coasts worldwide. Some species build above-ground sedimentary structures at or near the opening to their burrows. The functions and shapes of these constructions vary interspecifically and according to the sex of the builder. Here, we compile the dispersed reports on these structures, suggest uniform naming for different shapes, review explanations for their functions and explore associations between the attributes of builders and their structures. We found that 47 fiddler crab species build at least one type (or subtype) of structure, including chimneys, hoods, pillars, semidomes, mudballs, and rims. Sedimentary structures show a strong association with sediment type as well as builder front type, genus and sex, but not with fiddler crab clade. Experimental studies have revealed distinct, sometimes multiple functions for some of these structures (e.g., female attraction, reduction of aggressive behavior and/or landmark orientation); however, most studies have been observational leaving the proposed functions of these structures for many species untested. Both field and laboratory experiments as well as observational studies can help us to better understand these sedimentary structures and their role in fiddler crab behavior and ecology.publishedVersio

Filosofía realista de la educación argentina

Fil: Pró, Diego F.. Universidad Nacional de TucumánFil: Silva, Juan Carlos. Universidad Nacional de Cuy