On the dynamics of a class of multi-group models for vector-borne diseases

The resurgence of vector-borne diseases is an increasing public health concern, and there is a need for a better understanding of their dynamics. For a number of diseases, e.g. dengue and chikungunya, this resurgence occurs mostly in urban environments, which are naturally very heterogeneous, particularly due to population circulation. In this scenario, there is an increasing interest in both multi-patch and multi-group models for such diseases. In this work, we study the dynamics of a vector borne disease within a class of multi-group models that extends the classical Bailey-Dietz model. This class includes many of the proposed models in the literature, and it can accommodate various functional forms of the infection force. For such models, the vector-host/host-vector contact network topology gives rise to a bipartite graph which has different properties from the ones usually found in directly transmitted diseases. Under the assumption that the contact network is strongly connected, we can define the basic reproductive number $\mathcal{R}_0$ and show that this system has only two equilibria: the so called disease free equilibrium (DFE); and a unique interior equilibrium---usually termed the endemic equilibrium (EE)---that exists if, and only if, $\mathcal{R}_0>1$. We also show that, if $\mathcal{R}_0\leq1$, then the DFE equilibrium is globally asymptotically stable, while when $\mathcal{R}_0>1$, we have that the EE is globally asymptotically stable

THRESHOLD MODELS IN THEORY AND PRACTICE

Threshold models have gained much recent attention in applied economics for modeling nonlinear behavior. The appeal for these models is due in part to the observable pattern that many economic variables follow, such as asymmetric adjustment towards equilibrium. This paper reviews the literature and provides links to software programs.Research Methods/ Statistical Methods,

_Limusaurus_ and bird digit identity

_Limusaurus_ is a remarkable herbivorous ceratosaur unique among theropods in having digits II, III and IV, with only a small metacarpal vestige of digit I. This raises interesting questions regarding the controversial identity of avian wing digits. The early tetanuran ancestors of birds had tridactyl hands with digital morphologies corresponding to digits I, II & III of other dinosaurs. In bird embryos, however, the pattern of cartilage formation indicates that their digits develop from positions that become digits II, III, & IV in other amniotes. _Limusaurus_ has been argued to provide evidence that the digits of tetanurans, currently considered to be I, II and III, may actually be digits II, III, & IV, thus explaining the embryological position of bird wing digits. However, morphology and gene expression of the anterior bird wing digit specifically resemble digit I, not II, of other amniotes. We argue that digit I loss in _Limusaurus_ is derived and thus irrelevant to understanding the development of the bird wing

Photon correlations in positron annihilation

The two-photon positron annihilation density matrix is found to separate into a diagonal center of energy factor implying maximally entangled momenta, and a relative factor describing decay. For unknown positron injection time, the distribution of the difference in photon arrival times is a double exponential at the para-Ps decay rate, consistent with experiment (V. D. Irby, Meas. Sci. Technol. 15, 1799 (2004)).Comment: Accepted for publication in Phys. Rev.

Alien Registration- Gauthier, Joseph O. (Lewiston, Androscoggin County)

https://digitalmaine.com/alien_docs/29860/thumbnail.jp

Ultra-high-frequency piecewise-linear chaos using delayed feedback loops

We report on an ultra-high-frequency (> 1 GHz), piecewise-linear chaotic system designed from low-cost, commercially available electronic components. The system is composed of two electronic time-delayed feedback loops: A primary analog loop with a variable gain that produces multi-mode oscillations centered around 2 GHz and a secondary loop that switches the variable gain between two different values by means of a digital-like signal. We demonstrate experimentally and numerically that such an approach allows for the simultaneous generation of analog and digital chaos, where the digital chaos can be used to partition the system's attractor, forming the foundation for a symbolic dynamics with potential applications in noise-resilient communications and radar

La forêt méditerranéenne : un modèle de forêt multifonctionnelle

A l'occasion de la publication du n°100 de la revue Forêt Méditerranéenne, il a été demandé aux grandes institutions nationales qu'elles nous présentent leur vision des espaces forestiers méditerranéens "depuis Paris". Cet article nous donne le regard porté par le Ministère chargé de l'Ecologie sur la forêt méditerranéenne

Supersymmetric free-damped oscillators: Adaptive observer estimation of the Riccati parameter

A supersymmetric class of free damped oscillators with three parameters has been obtained in 1998 by Rosu and Reyes through the factorization of the Newton equation. The supplementary parameter is the integration constant of the general Riccati solution. The estimation of the latter parameter is performed here by employing the recent adaptive observer scheme of Besancon et al., but applied in a nonstandard form in which a time-varying quantity containing the unknown Riccati parameter is estimated first. Results of computer simulations are presented to illustrate the good feasibility of this approach for a case in which the estimation is not easily accomplished by other meansComment: 8 pages, 6 figure

Antimicrobial Effects of Compounds Used in Cleaning Wipes

The antimicrobial effectiveness and level of biofilm inhibition of three compounds from Rockline Industries were tested, along with five compounds made by the St. Norbert College Organic Chemistry Department. The Rockline compounds, ColaLipid (CL), Sodium Benzoate (NaB) and Benzoic Acid (BA), were solubilized in 10% DMSO and tested at concentrations of 0.15%, 0.10%, and 0.01%. To ensure that any growth effects were due to the compounds in question, DMSO was also tested for antimicrobial activity. The compounds were tested against safe relative of eight bacteria of clinical importance (Acinetobacter baylyi, Bacillus subtilis, Escherichia coli, Enterococcus raffinosus, Enterobacter aerogenes, Pseudomonas fluorescens, Pseudomonas putida, Staphylococcus epidermidis) and one species of fungus (Candida albicans). The antimicrobial properties of these compounds were measured by reading absorbance at 600 nm of overnight cultures. Biofilm formation inhibition was measured using a crystal violet biofilm assay. ColaLipid and Benzoic Acid were found to inhibit growth of the bacterial and fungal strains, while Sodium Benzoate did not. Of the compounds synthesized by in St. Norbert organic chemists, two showed consistent inhibition of growth and three did not. ColaLipid, Benzoic Acid, and one organic compound showed consistent inhibition of biofilm formation.https://digitalcommons.snc.edu/collaborative_presentations/1081/thumbnail.jp