Competition, Bargaining Power, and the Cattle Cycle

Cattle production follows a dynamic cycle that has often been analyzed, and cattle markets receive much scrutiny because of the potential for buyer market power. The relationship between the two has been little studied, however. This paper provides a simple conceptual framework to study how the cattle cycle and market concentration jointly affect the bargaining power of producers and packers yielding the following main results. Not surprisingly, a larger cattle stock reduces producers' bargaining position, which results in a lower fed cattle price. More importantly, however, the cattle stock's negative effect on price is magnified by the market concentration in beef packing. Thus, the cycle itself is very importantly related to a posited cycle of bargaining power between cattle producers and beef packers. Secondly, the model also shows how beef packers may use the special feature of cattle as both consumption and capital goods to lower the cattle price by influencing cattle inventories.Livestock Production/Industries,

Defect Engineering: Graphene Gets Designer Defects

An extended one-dimensional defect that has the potential to act as a conducting wire has been embedded in another perfect graphene sheet.Comment: 2 pages, 1 figur

First-Order Logic Definability of Free Languages

Operator Precedence Grammars (OPGs) define a deterministic class of context-free languages, which extend input-driven languages and still enjoy many properties: they are closed w.r.t. Boolean operations, concatenation and Kleene star; the emptiness problem is decidable; they are recognized by a suitable model of pushdown automaton; they can be characterized in terms of a monadic second-order logic. Also, they admit efficient parallel parsing. In this paper we introduce a subclass of OPGs, namely Free Grammars (FrGs); we prove some of its basic properties, and that, for each such grammar G, a first-order logic formula ψ can effectively be built so that L(G) is the set of all and only strings satisfying ψ. FrGs were originally introduced for grammatical inference of programming languages. Our result can naturally boost their applicability; to this end, a tool is made freely available for the semiautomatic construction of FrGs

Logic Characterization of Invisibly Structured Languages: The Case of Floyd Languages

Operator precedence grammars define a classical Boolean and deterministic context-free language family (called Floyd languages or FLs). FLs have been shown to strictly include the well-known Visibly Pushdown Languages, and enjoy the same nice closure properties. In this paper we provide a complete characterization of FLs in terms of a suitable Monadic Second-Order Logic. Traditional approaches to logic characterization of formal languages refer explicitly to the structures over which they are interpreted - e.g, trees or graphs - or to strings that are isomorphic to the structure, as in parenthesis languages. In the case of FLs, instead, the syntactic structure of input strings is “invisible” and must be reconstructed through parsing. This requires that logic formulae encode some typical context-free parsing actions, such as shift-reduce ones

Social Cloud-based Cognitive Reasoning for Task-oriented Recommendation

The Social Internet of Things (SIoT) is recently being promoted in literature for enabling the integration of devices into users’ daily life. This integration can be achieved by taking advantage of the inter-connectivity and the user-friendliness offered by Social Network Services (SNS). The novel SIoT paradigm opens the door for studying the intelligence mechanisms required to enhance services adaptability. We study the integration of cognitive reasoning into SIoT for providing recommendation of quotidian tasks in smart homes. In order to achieve situation characterization, reasoning about physical as well as social aspects of context is required. Thus, as a service built on top of Social Cloud (SoC), we propose an intelligent recommendation (InRe) framework. This framework applies the reasoning mechanism on context elements which are represented using ontologies. ThigsChat is provided as a proof-of-concept prototype. Initial experiments indicate a considerable improvement in adaptability of recommendation results to users’ situations

Discrete transverse superconducting modes in nano-cylinders

Spatial variation in the superconducting order parameter becomes significant when the system is confined at dimensions well below the typical superconducting coherence length. Motivated by recent experimental success in growing single-crystal metallic nanorods, we study quantum confinement effects on superconductivity in a cylindrical nanowire in the clean limit. For large diameters, where the transverse level spacing is smaller than superconducting order parameter, the usual approximations of Ginzburg-Landau theory are recovered. However, under external magnetic field the order parameter develops a spatial variation much stronger than that predicted by Ginzburg-Landau theory, and gapless superconductivity is obtained above a certain field strength. At small diameters, the discrete nature of the transverse modes produces significant spatial variations in the order parameter with increased average magnitude and multiple shoulders in the magnetic response.Comment: 10 pages, 8 figure