170,845 research outputs found
Zappa-Szep products of semigroups and their C*-algebras
No full textZappa-Szep products of semigroups provide a rich class of examples of semigroups that include the self-similar group actions of Nekrashevych. We use Li's construction of semigroups C*-algebras to associate a C*-algebra to Zappa-Szep products and give an explicit presentation of the algebra. We then define a quotient C*-algebra that generalises the Cuntz-Pimsner algebras for self-similar actions. We indicate how knowne examples, previously viewed as distinct classes, fit into our unifying framework. We specifically discuss the Baumslag-Solitar groups, the binary adding machine, the semigroup NXNx, and the ax+b semigroup ZXZx
Zappa-Szép product groupoids and C*-blends
No full textWe study the external and internal Zappa–Szép product of topological groupoids. We show that under natural continuity assumptions the Zappa–Szép product groupoid is étale if and only if the individual groupoids are étale. In our main result we show that the C∗C∗-algebra of a locally compact Hausdorff étale Zappa–Szép product groupoid is a C∗C∗-blend, in the sense of Exel, of the individual groupoid C∗C∗-algebras. We finish with some examples, including groupoids built from ∗∗-commuting endomorphisms, and skew product groupoids
Zappa-Szép product groupoids and C*-blends
No full textWe study the external and internal Zappa-Szép product of topological groupoids.We show that under natural continuity assumptions the Zappa-Szép product groupoid is étale if and only if the individual groupoids are étale. In our main result we show that the C*-algebra of a locally compact Hausdorff étale Zappa-Szép product groupoid is a C*-blend, in the sense of Exel, of the individual groupoid C*-algebras. We finish with some examples, including groupoids built from ⁎-commuting endomorphisms, and skew product groupoids
Zappa–Szép products of semigroups and their C*-algebras
No full textZappa–Szép products of semigroups provide a rich class of examples of semigroups that include the self-similar group actions of Nekrashevych. We use Li's construction of semigroup C*-algebras to associate a C*-algebra to Zappa–Szép products and give an explicit presentation of the algebra. We then define a quotient C*-algebra that generalises the Cuntz–Pimsner algebras for self-similar actions. We indicate how known examples, previously viewed as distinct classes, fit into our unifying framework. We specifically discuss the Baumslag–Solitar groups, the binary adding machine, the semigroup N⋊N×, and the ax+b-semigroup Z⋊Z×
Zappa-Szep products of semigroups and their C*-algebras
No full textZappa-Szep products of semigroups provide a rich class of examples of semigroups that include the self-similar group actions of Nekrashevych. We use Li's construction of semigroup C*-algebras to associate a C*-algebra to Zappa-Szep products and give an explicit presentation of the algebra. We then define a quotient C*-algebra that generalises the Cuntz-Pimsner algebras for self-similar actions. We indicate how known examples, previously viewed as distinct classes, fit into our unifying framework. We specifically discuss the Baumslag-Solitar groups, the binary adding machine, the semigroup N x N×, and the ax + b-semigroup Z x Z×
Development and delivery of a pilot service for the physical infrastructure of metrofood-RI
No full textThe importance of Metrofood Ri for/in the development of the agrofood sector in the South Eastern European (SEE) partner countries
No full textMETROFOOD-RI is a European Research Infrastructure (RI) aiming at promoting metrology in food and nutrition. In the present work, a mapping of existing RIs and networks of the South Eastern European (SEE) METROFOOD partner countries (i.e. FYROM, Greece, Hungary, Republic of Moldova, Romania, Slovenia), related directly or indirectly to the Agrifood sector, is presented and discussed. As reference METROFOOD partner country, The Netherlands is considered. Copyright� (2017) by the International Measurement Confederation (IMEKO). All rights reserved
Reference materials in support to food traceability
No full textTraceability represents the ability to trace and follow a food and any ingredient through all the stages from production, up to the distribution and the end use. Thanks to the progress of knowledge, technologies and data processing systems, it is possible to identify markers and develop systems and analytical methods for demonstrating the origin and authenticity of raw materials and products. The application of the metrological rules to chemical and biological measurements requires more and more a wide availability of Reference Materials (RMs), which constitute very often the only way for establishing metrological traceability of the measurement results and for quantifying measurement uncertainty. In this work, an examination of the current availability of RMs for traceability of food products is reported, and the ENEA activities on the development of new RMs for food traceability are described
Feasibility studies for new food matrix-Reference Materials
No full textThis paper reports about the feasibility studies for the development of new food matrix-Reference Materials (RMs) aimed to evaluate quality, safety and traceability of selected food products, performed during the "Early Phase" (H2020 INFRADEV-02-2016 PRO-METROFOOD, G.A. 739568) of METROFOOD-RI "Infrastructure for Promoting Metrology in Food and Nutrition" (ESFRI Domain "Health & Food"), in the frame of the development of pilot services. With this purpose, batches of oyster tissue, rice grains and rice flour were prepared in lyophilized form (oyster tissue) or in their raw form (rice), homogenised, partitioned and then characterised for a very wide set of parameters, such as: contaminants, biomarkers, stable isotopes, markers of origin/authenticity. Such a wide characterisation was aimed to involve as many laboratories as possible and to go forward the development of "Multipurpose-RMs", meaning new RMs having certified, reference or information values for several different parameters. Homogeneity studies and stability studies under thermal and luminous stress are underway. © 2018 Institute of Physics Publishing. All rights reserved
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