A review on the use of hormones in fish farming: analytical methods to determine their residues.

Hormones are used in fish farming to increase fish production when one sex of a species has the capacity to grow bigger and faster than the other sex. The technique to increase fish production based on sexual dimorphism mostly uses estrogens and androgens. These chemicals must be handled carefully to ensure environmental, biological and food safety, since they can contaminate the environment and promote changes in the endocrine system inducing adverse effects on the consumer health. Another important issue is the reliability of the analytical methods used to identify and/or quantify hormone residues in the meat of treated fish. Therefore, the aim of this review is to bring into view the use of hormones in fish farming, the possible impacts of this practice on humans and on the environment and to discuss the current methods of analysis for determining the hormone residues in food matrices, especially in fish

Logistics service providers and Industry 4.0: A systematic literature review

Background: Industry 4.0 is one of the topics related to manufacturing, supply chain and logistics that has received great interest from the academic community, organizations and governments in the last decade. Problem statement: Several published articles discuss and seek to conceptualize what the fourth industrial revolution is, but no research relates industry 4.0 in the context of logistics service providers (LSPs) in a clear and structured way. Objectives: This study aims to fill this research gap, proposing a conceptual framework and addressing the challenges, barriers and organizational dimensions that need adaptation to insert LSPs in the new Industry 4.0 environment. Methods: This theoretical and conceptual study uses the Systematic Literature Review (SLR) as a research method to understand the Industry 4.0 phenomenon in the context of LSPs. Contributions: The relevant constructs identified in this research will help professionals and organizations that provide logistics services to develop strategies and encourage new research in the 15 field of Industry 4.0 from the perspective of LSPs. Results: In addition, this research identified and generally consolidated six dimensions, as a result of this innovative study a conceptual framework is presented

Job security and long-term investment: an experimental analysis

We investigate an experimental labor market setting in which we introduce the novel aspect that workers have the chance of investing money in a long-term project in order to increase their income. We find a strong relationship between what happens inside the labor market (worker's performance) and what happens outside the labor market (long-term investment). Contrary to the theoretical predictions with selfish preferences, we find that the mere presence of long-term projects acts as an effort-enforcement device; this effect seems to be driven by an increase in long-term employment relationships. In the other direction, long-term labor relationships seem to provide a safer environment for undertaking successful long-term projects. This article also considers three different types of experimental labor contracts. We find that performance-based dismissal barriers, whereby firms are required to retain workers if they have satisfied the effort level required by firms, lead to more long-term employment relationships and higher overall productivity. As theory predicts, the presence of renewable dismissal barriers makes it likely that workers will provide the desired effort level. Firms appear to correctly anticipate this, leading to greater social efficiency

The hidden advantage of delegation: pareto-improvements in a gift-exchange game

This paper analyzes the effect on performance and earnings of delegating the wage choice to employees. Our results how that such delegation significantly increases effort levels. Moreover, we observe a Pareto-improvement, as the earnings of both employers and employees increase when employers delegate than when they do not. Interestingly, we also find that the employees’ performance under delegation is higher than under non-delegation, even for similar wages. While there is strong evidence that behavior reflects strategic considerations, this result also holds for one-shot interactions. A possible non-strategic motivation explaining the positive reaction to delegation is a sense of enhanced responsibility

The Classical Schrodinger's Equation

A non perturbative numerical method for determining the discrete spectra is deduced from the classical analogue of the Schrodinger's equation. The energy eigenvalues coincide with the bifurcation parameters for the classical orbits.Comment: UUEncoded Postscript, 18 pages, 4 figures inserted in tex

On the asymptotic behaviour of solutions to the fractional porous medium equation with variable density

We are concerned with the long time behaviour of solutions to the fractional porous medium equation with a variable spatial density. We prove that if the density decays slowly at infinity, then the solution approaches the Barenblatt-type solution of a proper singular fractional problem. If, on the contrary, the density decays rapidly at infinity, we show that the minimal solution multiplied by a suitable power of the time variable converges to the minimal solution of a certain fractional sublinear elliptic equation.Comment: To appear in DCDS-

Completeness of evanescent modes in layered dielectrics

In the presence of a dielectric slab, the modes of the free electromagnetic field comprise traveling modes, consisting of incoming, reflected, and transmitted parts, as well as trapped modes that are subject to repeated total internal reflection and emerge as evanescent field outside the slab. Traveling modes have a continuous range of frequencies, but trapped modes occur only at certain discrete frequencies. We solve the problem of which relative weight to use when summing over all modes, as commonly required in perturbative calculations. We demonstrate the correctness of our method by showing the completeness of electromagnetic field modes in the presence of a dielectric slab. We derive a convenient method of summing over all modes by means of a single contour integral, which is very useful in standard quantum electrodynamic calculations