Expectations, Network Effects and Timing of Technology Adoption: Some Empirical Evidence from a Sample of SMEs in Italy

We provide evidence on the influence of expectations and network effects on the timing of technological adoption. By considering a sample of SMEs operating in Italy we focus on the determinants of their decision to adopt Fast Ethernet, a communication standard for Local Area Networks (LANs). We find that both expectations and network effects significantly affect the timing of adoption. In particular, price expectations generally tend to delay adoption and (indirect) network effects in the form of backward compatibility as well as informational spillovers tend to foster adoption. Firm size also matters.diffusion, network effects, expectations, LAN equipment, SMEs

Kinetically constrained spin models

We analyze the density and size dependence of the relaxation time for kinetically constrained spin models (KCSM) intensively studied in the physical literature as simple models sharing some of the features of a glass transition. KCSM are interacting particle systems on $\Z^d$ with Glauber-like dynamics, reversible w.r.t. a simple product i.i.d Bernoulli($p$) measure. The essential feature of a KCSM is that the creation/destruction of a particle at a given site can occur only if the current configuration of empty sites around it satisfies certain constraints which completely define each specific model. No other interaction is present in the model. From the mathematical point of view, the basic issues concerning positivity of the spectral gap inside the ergodicity region and its scaling with the particle density $p$ remained open for most KCSM (with the notably exception of the East model in $d=1$ \cite{Aldous-Diaconis}). Here for the first time we: i) identify the ergodicity region by establishing a connection with an associated bootstrap percolation model; ii) develop a novel multi-scale approach which proves positivity of the spectral gap in the whole ergodic region; iii) establish, sometimes optimal, bounds on the behavior of the spectral gap near the boundary of the ergodicity region and iv) establish pure exponential decay for the persistence function. Our techniques are flexible enough to allow a variety of constraints and our findings disprove certain conjectures which appeared in the physical literature on the basis of numerical simulations

Multidimensional Stationary Probability Distribution for Interacting Active Particles

We derive the stationary probability distribution for a non-equilibrium system composed by an arbitrary number of degrees of freedom that are subject to Gaussian colored noise and a conservative potential. This is based on a multidimensional version of the Unified Colored Noise Approximation. By comparing theory with numerical simulations we demonstrate that the theoretical probability density quantitatively describes the accumulation of active particles around repulsive obstacles. In particular, for two particles with repulsive interactions, the probability of close contact decreases when one of the two particle is pinned. Moreover, in the case of isotropic confining potentials, the radial density profile shows a non trivial scaling with radius. Finally we show that the theory well approximates the "pressure" generated by the active particles allowing to derive an equation of state for a system of non-interacting colored noise-driven particles.Comment: 5 pages, 2 figure

Season and altitude effects on milk fatty acid profile in Sarda dairy sheep flocks

Diet plays a major role in modulating the fatty acid composition of ruminant milk. It is also well known that the intake of fresh forages has a positive influence on polyunsaturated fatty acid (PUFA), particularly CLA and omega- 3, compared with diets based on dry forage and concentrates. Altitude influences, directly, grass availability and botanical composition of the pasture, and, indirectly, the amount of concentrate supplemented to the diet. Therefore, the altitude where farms are located at may give indirect information about the type of feeding system trough analysis of milk fat. The objective of this survey was to investigate variations in the milk fatty acid profile, focusing on the content of vaccenic acid (VA), conjugated linoleic acid (CLA) and n-3 fatty acid (FA), of Sarda dairy ewes flocks located at different altitudes throughout Sardinia. Bulk milk samples were collected in spring (April) and in summer (July) from 36 flocks located at different altitudes: 3 flocks in the lowlands (Low), 3 flocks in the hills (Hill) and 3 in the highlands (High) in 4 provinces (Sassari, Nuoro, Oristano and Cagliari) of Sardinia (Italy). Milk fatty acid profile was analyzed by gas-chromatography. Data were analyzed with a linear model with altitude (A), season (S), province (P) and altitude x season as fixed factors. The interaction was never significant. The season influenced significantly almost all fatty acids analyzed. The proportion of short chain FA (C4-C10) decrease (10.0 vs 7.0 mg/100 mg FA; P<0.01) and that of medium chain FA increase (43.2 vs 45.5 mg/100 mg FA; P<0.10) from spring to summer. The long chain FA did not vary between spring and summer but the concentration of oleic acid (C18:1 cis9) increased significantly from spring to summer (22.3 vs 25.1 mg/100 mg FA; P<0.01). The proportion of n-3 FA was higher in spring than summer (1.2 vs 0.7 for n- 3 FA; P<0.01). The variation in n-3 FA in milk fat was mainly due to the variation in a-linolenic acid (ALA; 18:3n- 3) which decrease from 1.0 to 0.5 mg/100 mg FA from spring to summer. The same pattern was showed by vaccenic acid (VA; trans-11 18:1) that decrease from 1.6 vs 0.8 mg/100 mg FA. No variation in cis9, trans11 CLA has been observed between spring and summer (1.0 vs 0.8 mg/100 mg FA). A reduction of PUFA (5.64 vs 5.10; P<0.10), n3/n6 ratio (0.38 vs 0.21) and content of C20:5 n-3 (0.13 vs 0.07 mg/100 mg FA) from spring to summer has been observed. Unexpectedly, the milk FA profile was not affected by altitude, except for C18:1 c9, probably because of the low number of samples analyzed

Introduction to astronomy didactics for basic education teachers using the Diary of the Sky as a methodological strategy

This study we are presenting, is part of the subproject titled The Sky of North and The Sky of South: A cooperative experience between Brazil and Italy, of the CAPES/PrInt Project for the internationalization of scientific research, of the Graduate Program in Science Education, School of Sciences, UNESP, Campus de Bauru, São Paulo, Brazil, in academic partnership with the Università “La Sapienza” di Roma and the Movimento di Cooperazione Educativa (MCE) di Roma, Italy. This is a study within the scope of teacher training for the teaching of Astronomy, especially for the didactics of Astronomy, for students in the early years of Basic Education (Langhi & Nardi, 2012). The initial proposal came from one of the stages of a broader research (Fernandes, 2018), with the translation and adaptation of the didactic material Il Diario del Cielo (Lanciano, 2013), of Italian origin, for use in the tropical belt of the Southern Hemisphere, especially for the geographic coordinates of the region of Bauru, Sao Paulo, Brazil (Lanciano et al., 2019a). Il Diario del Cielo is the result of the experience of Professor Nicoletta Lanciano (Università “La Sapienza” di Roma, Italy) in teaching higher education and is organized based on the results of the research and teaching activities of Astronomy, developed within the scope of the Gruppo de Ricerca sulla Pedagogia del Cielo, from MCE, in Italy. It consists of material in the format of an astronomical school diary, to work with astronomical phenomena concepts, starting from a sequence of activities developed according to the bases of Observational Astronomy. Students and teachers are challenged to record daily, during the school year, data from direct observation of astronomical phenomena, such as hypotheses, inferences, comments, impressions and reflections, questions, suggestions for similar content to be researched, information for further checking, images, among other class and extra class annotations. The implementation of the didactic resource The Diary of the Sky seeks to provide educational situations that involve elements of direct and continuous observation of the sky and surroundings, activities with explanatory didactic models, work in a natural and outdoor environment, and the use of low-cost material resources (Fernandes, 2018), allowing students to continue to gain familiarity with astronomical phenomena. This subproject has provided, in the last six years, in its different annual editions of the course, called The Diary of the Sky - Introduction to Astronomy Didactics for Basic Education Teachers, the upskilling of dozens of teachers working in Basic Education, linked to the Bauru Municipal and State Education Departments, in basic astronomy notions and, by extension, to hundreds of elementary school students. Using the Diary of the Sky every day, students follow and note the positions of the stars in relation to the horizon, the position of the shadow itself, or the shadows of objects projected on the ground, for example. Students complete, in three-dimensional space and in real time, daily recordings of their own discoveries, giving greater meaning to concepts that involve, for example, day and night phenomena, seasons or phases of the moon. In this sense, the work with The Diary of the Sky helps to put in dialogue what is observed daily in the here and now with the conceptual, cognitive and historical-cultural aspects linked to Astronomy and its teaching (Lanciano, 2019b). REFERENCES Fernandes, T. C. D. (2018). Um estudo sobre a formação continuada de professores da Educação Básica para o ensino de Astronomia utilizando o “Diário do Céu” como estratégia de ensino. Doctoral’s Thesis in Science Education (Bauru: São Paulo State University – Unesp) p 269. Lanciano, N., Nardi, R., Langhi, R., & Fernandes, T. C. D. (2019a). O Diário do Céu: Ano Escolar 2019, Editora Livraria da Física, São Paulo, 372p. Lanciano, N. (2019b). Strumenti per i Giardini del Cielo. (3rd ed.). (Parma, Italia: Asterios Editore-Abiblio, Quaderni di Cooperazione Educativa, MCE). Lanciano, N. (2013). Il Diario del Cielo: Anno Scolastico 2013-2014 (Rome: New Press Edizioni). Langhi, R. &  Nardi, R. (2012). Educação em Astronomia: repensando a formação de professores. (São Paulo: Escrituras)