1,027 research outputs found
Far from home....the first documented capture of the genus Elops (Actinopterygii, Elopidae) from the Mediterranean
The tenpounder fish genus Elops Linnaeus, 1766 was recorded for the first time from the Mediterranean in October 2019, as a single individual was caught in Maltese waters. The genus has a disparate global distribution consisting of west Atlantic and west Pacific tropical and sub-tropical areas. A single individual was caught, but not retained, during artificial lighting-assisted purse seining, and the identification of the genus was determined based upon photographs submitted by the fisherman. The mechanisms of range expansion of the genus from the Atlantic into the Mediterranean are discussed.peer-reviewe
Estimating Vertical Foreclosure in U.S. Gasoline Supply
We examine the competitive effects of the vertical integration of gasoline refineries and retailers in the U.S. Adapting the first-order condition approach of static oligopoly games to the analysis of vertically related oligopolies, we develop a novel framework for directly evaluating the strategic foreclosure effect and the efficiencies associated with vertical integration. We find significant evidence for both vertical foreclosure and efficiency benefits. The foreclosure effect dominates the efficiency benefits for more than half of the refining firms in the sample. Vertical foreclosure is found to increase the wholesale price of refined gasoline by 0.2 to 0.6 cents per gallon.vertical integration, separation, foreclosure, market conduct, petroleum industry
Estimating Vertical Foreclosure in U.S. Gasoline Supply
We examine the competitive effects of the vertical integration of gasoline refineries and retailers in the U.S. Adapting the first-order condition approach of static oligopoly games to the analysis of vertically related oligopolies, we develop a novel framework for directly evaluating the strategic foreclosure effect and the effciency benefits associated with vertical integration. Applying this framework, we find significant evidence for both vertical foreclosure and effciency benefits. The foreclosure effect dominates the effciency benefits for more than half of the refining firms in the sample. Vertical foreclosure is found to increase the wholesale price of refined gasoline by 0.2 to 0.6 cents per gallon.vertical integration, separation, foreclosure, market conduct, petroleum industry
Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis
Japanese iodine intake from edible seaweeds is amongst the highest in the world. Predicting the type and amount of seaweed the Japanese consume is difficult due to day-to-day meal variation and dietary differences between generations and regions. In addition, iodine content varies considerably between seaweed species, with cooking and/or processing having an influence on iodine content. Due to all these factors, researchers frequently overestimate, or underestimate, Japanese iodine intake from seaweeds, which results in misleading and potentially dangerous diet and supplementation recommendations for people aiming to achieve the same health benefits seen by the Japanese. By combining information from dietary records, food surveys, urine iodine analysis (both spot and 24-hour samples) and seaweed iodine content, we estimate that the Japanese iodine intake--largely from seaweeds--averages 1,000-3,000 μg/day (1-3 mg/day)
Exploring 1H NMR relaxometry for wine traceability and authenticity assessment
Mestrado em Engenharia de Viticultura e Enologia (Double degree) / Instituto Superior de Agronomia. Universidade de Lisboa / Faculdade de Ciências. Universidade do PortoThe development of analytical methodologies for wine authenticity assessment is one of the most challenging issues for the scientific community. In this study, the potential analytical applications of 1H NMR relaxometry, in view to wine authenticity investigation, were explored. For that, proton longitudinal relaxation rate dispersions in the range 0.04-300 MHz were investigated in three white and three red varietal wines from Tapada da Ajuda (Lisbon), obtained from Vitis vinifera L. grape varieties, namely Alvarinho, Arinto, Cabernet Sauvignon, Moscatel Graúdo, Touriga Nacional and Trincadeira, from vintages 2008 and 2017 for a total of twelve bottles. To evaluate rain as an environmental source of variability pluviometric data were considered. Dispersions associable to the presence of paramagnetic ions were observed at low frequencies but the results for wine iron content cannot explain the effect. Correlations between the wine characters and the areas drawn by the most representative relaxometry models show an effect of alcoholic strength by volume, glycerol and total dry matter suggesting wine viscosity to modulate relaxivity. To the best of our knowledge, for the first time wine physical-chemical characteristics and glycerol content have been compared to NMR relaxation rate profiles. To investigate the paramagnetic relaxation and evaluate the relaxation associated to wine hydro-alcoholic matrix, water-ethanol mixtures were tested, and linear regressions were obtained. Comparing the results with bibliographic sources, the paramagnetic enhancement on relaxation profiles was associated to the presence of manganese(II), but no parameters have been fitted from the models. The dispersions highlighted possible cross relaxations in the 1.5-6 MHz frequency range. The presence of nitrogen diluted into the wine could explain this behaviour. To inspect how each physical-chemical parameter impacts on wine relaxation profiles the knowledge of manganese content is crucialN/
On a notion of entropy in coarse geometry
AbstractThe notion of entropy appears in many branches of mathematics. In each setting (e.g., probability spaces, sets, topological spaces) entropy is a non-negative real-valued function measuring the randomness and disorder that a self-morphism creates. In this paper we propose a notion of entropy, called coarse entropy, in coarse geometry, which is the study of large-scale properties of spaces. Coarse entropy is defined on every bornologous self-map of a locally finite quasi-coarse space (a recent generalisation of the notion of coarse space, introduced by Roe). In this paper we describe this new concept, providing basic properties, examples and comparisons with other entropies, in particular with the algebraic entropy of endomorphisms of monoids
Coarse geometry: a foundational and categorical approach with applications to groups and hyperspaces
The topic of the manuscript is coarse geometry, also known as large-scale geometry, which is the study of large-scale properties of spaces. It found applications in geometric group theory after the work of Gromov, and in Novikov and coarse Baum-Connes conjectures.
The thesis is divided into three parts. In the first one, we provide a foundational and categorical approach to coarse geometry. Large-scale geometry was originally developed for metric spaces and then Roe introduced coarse structures as a large-scale counterpart of uniformities. However, coarse spaces are innerly symmetric objects, and thus are not suitable to parametrise asymmetric objects such as monoids and quasi-metric spaces. In order to fill the gap, we introduce quasi-coarse spaces. Moreover, we consider also semi-coarse spaces and entourage spaces. These objects induce para-bornologies, quasi-bornologies, semi-bornologies, pre-bornologies (also known as bounded structures) and bornologies, and this process is similar to the definition of uniform topology from a (quasi-)uniform space. We study all the notions introduced and recalled to find extensions of classical results proved for metric or coarse spaces, and similarities with notions and properties for general topology. Furthermore, we study the categories of those objects and the relations among them. In particular, since all of them are topological categories, we have a complete understanding of their epimorphisms and monomorphisms, and the description of many categorical constructions. Among them, of particular interest are quotients. We then focus our attention on Coarse, the category of coarse spaces and bornologous maps, discussing its closure operators and the cowellpoweredness of its epireflective subcategories, and its quotient category Coarse/~, which turns out to be balanced and cowellpowered.
The second part is dedicated to study the large-scale geometry of algebraic objects, such as unitary magmas, monoids, loops and groups. In particular, we focus on coarse groups (groups endowed with suitable coarse structures) and we investigate their category. We study different choices, underlining advantages and drawbacks. With some restrictions on the coarse groups that we are considering, if we enlarge the class of morphisms to contain bornologous quasi-homomorphisms (and not just bornologous homomorphisms), every coarse inverse of a homomorphism which is a coarse equivalence is a quasi-homomorphism. This observation is connected to the notion of localisation of a category and could provide a categorical justification to the notion of quasi-homomorphism. Once the categories of coarse groups are fixed, inspired by the notion of functorial topologies, we can introduce functorial coarse structures on Grp, the category of groups and homomorphisms, and on TopGrp, the category of topological groups and continuous homomorphisms. Among them, we pay attention to the ones induced by cardinal invariants, and to those associated to the family of relatively compact subsets. As for the latter functorial coarse structure, we study the transformation of large-scale properties along Pontryagin and Bohr functors.
The third part is devoted to coarse hyperspaces, which are suitable coarse structures on power sets of coarse spaces. This construction was introduced following the work of Protasov and Protasova and miming the classical notion of uniform hyperspace. We see how properties of the initial coarse space are reflected on the hyperspace. Since the coarse hyperspace is highly disconnected, it is convenient to consider some special subspaces of it. For example, if the base space is a coarse group, it is natural to consider the subspace structure induced on the lattice of subgroups, called subgroup exponential hyperballean. We show that both the subgroup exponential hyperballean and the subgroup logarithmic hyperballean, another coarse structure on the subgroup lattice, capture many properties of the group
Algebraic entropy of endomorphisms of M-sets
Abstract
The usual notion of algebraic entropy associates to every group (monoid) endomorphism a value estimating the chaos created by the self-map. In this paper, we study the extension of this notion to arbitrary sets endowed with monoid actions, providing properties and relating it with other entropy notions. In particular, we focus our attention on the relationship with the coarse entropy of bornologous self-maps of quasi-coarse spaces. While studying the connection, an extension of a classification result due to Protasov is provided
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