Real-time pcr method combined with a matrix lysis procedure for the quantification of listeria monocytogenes in meat products

In this study a real-time PCR method has been developed for the specific quantification of the foodborne pathogen Listeria monocytogenes on meat products through the gene hlyA. The PCR was combined with a matrix lysis that allowed the obtaining of the microorganisms without sample dilution and the elimination the PCR inhibitors from dry-cured ham. The qPCR method calibration curve had an efficiency of 100.4%, limits of detection and quantification were 30.1 ± 6.2 CFU/g which is under the legal limit of L. monocytogenes in ready-to-eat products, and an analytical variability <0.25 log hlyA gene copies/reaction. The analysis was performed simultaneously with the reference method ISO 11290-2. The comparison of the qPCR-matrix lysis results with the reference method showed an excellent correspondence, with a relative accuracy between 95.83–105.20%. Finally, the method was applied to commercial derived meat samples and the pathogen was quantified in one of the commercial samples assayed in 69.1 ± 13.9 CFU/g while the reference method did not quantify it. The optimized qPCR showed higher precision and sensitivity than the reference method at low concentrations of the microorganism in a shorter time. Therefore, qPCR-matrix lysis shows a potential application in the meat industry for L. monocytogenes routine control. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Measuring Egyptian Farmers’ Attitude Towards Staying Organic

Organic agriculture (OA) in Egypt is well-developed and still fast growing. Improving the relation between organic farmers and the other agents in the chain can provide a positive contribution to the whole organic chain competitiveness. One possible approach to investigate the farmers’ perceived role and satisfaction within the organic system is to explore the factors influencing their decision to stay organic. In particular, the aim of the present study was to measure the farmers’ attitude towards staying organic. Organic agricultural experts and institutional stakeholders were interviewed to complete a literature review and to obtain information about the Egyptian context. The survey questionnaire was pre-tested (n = 13) and then administered to a different sample (n = 232). A split-half validation procedure was used to evaluate and then confirm the factor structure. Explorative and confirmatory factor analysis yielded a final 29-item measure consisting of 8 distinct factors showing how organic agriculture influences a broad range of farmers’ life dimensions (environmental, economic, social, psychological). The significant role played by psychological and social factors in defining the farmers’ decision to stay organic emerged as a relatively unexpected outcome. The study supports the sustainable development of small family farmers, providing a useful tool to support the growth of organic production and consumption, mostly in developing countries. By monitoring farmers’ attitudes and perception towards OA, the instrument proposed in the present study can support policy makers, farmers’ organizations, civil society organizations (NGOs) and organic chains focal companies when defining policies, advocating campaigns, and chain coordination strategies for farmers involved in the organic food system development

Measuring Egyptian Farmers’ Attitude Towards Staying Organic

Organic agriculture (OA) in Egypt is well-developed and still fast growing. Improving the relation between organic farmers and the other agents in the chain can provide a positive contribution to the whole organic chain competitiveness. One possible approach to investigate the farmers’ perceived role and satisfaction within the organic system is to explore the factors influencing their decision to stay organic. In particular, the aim of the present study was to measure the farmers’ attitude towards staying organic. Organic agricultural experts and institutional stakeholders were interviewed to complete a literature review and to obtain information about the Egyptian context. The survey questionnaire was pre-tested (n = 13) and then administered to a different sample (n = 232). A split-half validation procedure was used to evaluate and then confirm the factor structure. Explorative and confirmatory factor analysis yielded a final 29-item measure consisting of 8 distinct factors showing how organic agriculture influences a broad range of farmers’ life dimensions (environmental, economic, social, psychological). The significant role played by psychological and social factors in defining the farmers’ decision to stay organic emerged as a relatively unexpected outcome. The study supports the sustainable development of small family farmers, providing a useful tool to support the growth of organic production and consumption, mostly in developing countries. By monitoring farmers’ attitudes and perception towards OA, the instrument proposed in the present study can support policy makers, farmers’ organizations, civil society organizations (NGOs) and organic chains focal companies when defining policies, advocating campaigns, and chain coordination strategies for farmers involved in the organic food system development

Spitzer's Identity and the Algebraic Birkhoff Decomposition in pQFT

In this article we continue to explore the notion of Rota-Baxter algebras in the context of the Hopf algebraic approach to renormalization theory in perturbative quantum field theory. We show in very simple algebraic terms that the solutions of the recursively defined formulae for the Birkhoff factorization of regularized Hopf algebra characters, i.e. Feynman rules, naturally give a non-commutative generalization of the well-known Spitzer's identity. The underlying abstract algebraic structure is analyzed in terms of complete filtered Rota-Baxter algebras.Comment: 19 pages, 2 figure

Generalized shuffles related to Nijenhuis and TD-algebras

Shuffle and quasi-shuffle products are well-known in the mathematics literature. They are intimately related to Loday's dendriform algebras, and were extensively used to give explicit constructions of free commutative Rota-Baxter algebras. In the literature there exist at least two other Rota-Baxter type algebras, namely, the Nijenhuis algebra and the so-called TD-algebra. The explicit construction of the free unital commutative Nijenhuis algebra uses a modified quasi-shuffle product, called the right-shift shuffle. We show that another modification of the quasi-shuffle product, the so-called left-shift shuffle, can be used to give an explicit construction of the free unital commutative TD-algebra. We explore some basic properties of TD-operators and show that the free unital commutative Nijenhuis algebra is a TD-algebra. We relate our construction to Loday's unital commutative dendriform trialgebras, including the involutive case. The concept of Rota-Baxter, Nijenhuis and TD-bialgebras is introduced at the end and we show that any commutative bialgebra provides such objects.Comment: 20 pages, typos corrected, accepted for publication in Communications in Algebr

Mixable Shuffles, Quasi-shuffles and Hopf Algebras

The quasi-shuffle product and mixable shuffle product are both generalizations of the shuffle product and have both been studied quite extensively recently. We relate these two generalizations and realize quasi-shuffle product algebras as subalgebras of mixable shuffle product algebras. As an application, we obtain Hopf algebra structures in free Rota-Baxter algebras.Comment: 14 pages, no figure, references update

Finite-Dimensional Calculus

We discuss topics related to finite-dimensional calculus in the context of finite-dimensional quantum mechanics. The truncated Heisenberg-Weyl algebra is called a TAA algebra after Tekin, Aydin, and Arik who formulated it in terms of orthofermions. It is shown how to use a matrix approach to implement analytic representations of the Heisenberg-Weyl algebra in univariate and multivariate settings. We provide examples for the univariate case. Krawtchouk polynomials are presented in detail, including a review of Krawtchouk polynomials that illustrates some curious properties of the Heisenberg-Weyl algebra, as well as presenting an approach to computing Krawtchouk expansions. From a mathematical perspective, we are providing indications as to how to implement in finite terms Rota's "finite operator calculus".Comment: 26 pages. Added material on Krawtchouk polynomials. Additional references include

Legionnaires' disease in Italy: results of the epidemiological surveillance from 2000 to 2011

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