Sepiolinae (Mollusca: Cephalopoda) from the Strait of Sicily

Nine species belonging to three genera of the subfamily Sepiolinae (Leach, 1817) were collected in the Strait of Sicily by two series of bottom trawl surveys carried out during the years 1985-87 and 1992: Sepiola rondeletii, Sepiola intermedia, Sepiola ligulata, Sepiola robusta, Sepiola affinis, Sepietta oweniana, Sepietta neglecta, Sepietta obscura and Rondeletiola minor. For each species, abundance, distribution, sex ratio and maturity condition were analysed. S. oweniana was the most abundant species, followed by R. minor, while the single record of S. ligulata indicates that the species is rare in the area. The bathymetric distributions observed generally agree with what is known for the species from the literature, but present data support the extension of the bathymetric range inhabited by S. robusta (down to 498 m). Mature specimens represented 81.8% of the examined sample, and no substantial differences in the percentages of mature individuals with season was noticeable; this supports the existence of an extended reproductive period in the Sepiolines

Collaboration experience in the supply chain of knowledge and patent development

In this paper we aim at understanding the role of collaboration experience in supply chains of knowledge (SCoK). The SCoK of a company is its supply chain not related to the flow of physical goods but to the flow of R&D commodities. R&D commodities are for example patents, technologies, research services, studies, and projects, and, in high-tech industries, their development and commercialization is considered as important as real products. To accomplish our aim in this paper we fulfil the following research objectives: 1) investigate the relationship between the collaboration experience in SCoK and the propensity of the firm to develop new patents; 2) examine how the structural embeddedness of the firm within its SCoK mediates this relationship. We ground our conceptual model on the supply chain, open innovation and social capital literatures and empirically test our hypotheses on a cross-sectional dataset of 208 biotech companies that have signed 612 SCoK agreements in the years 2006–2010. The key findings of this study are: first, accumulating experience in SCoK collaborations facilitates the development of new patents; second, being central and bridging structural holes within the SCoK are two means by which the experience in SCoK collaborations is translated into new patents

Sudden death and sudden birth of entanglement in common structured reservoirs

We study the exact entanglement dynamics of two qubits in a common structured reservoir. We demonstrate that, for certain classes of entangled states, entanglement sudden death occurs, while for certain initially factorized states, entanglement sudden birth takes place. The backaction of the non-Markovian reservoir is responsible for revivals of entanglement after sudden death has occurred, and also for periods of disentanglement following entanglement sudden birth.Comment: 4 pages, 2 figure

A Novel Logic and Approach to Speed up Simulation and Analysis of Production Systems

The paper describes a novel logic to model, simulate and analyze production systems using Discrete Event Simulation tools. An adaptable and flexible DES model has been developed to represent different manufacturing environments. The goal of the proposed DES-based parametric model is to offer to industrial analysts a compact, fast and easy way to configure and use decision support tools. The logic is based on elementary structures with a vertical multilayer architecture that permits entities to access and loop in multiple times. Since it has been assumed manufacturing systems are combination of elementary parts, the architecture of the model becomes quite simple since representing few structures only, and the simulation of heterogeneous systems is the result of as many iterations as needed by a user. This approach is adaptable both to SMEs and large companies, permitting to avoid the use of dedicated SW and allocated skilled person

Phenomenological memory-kernel master equations and time-dependent Markovian processes

Do phenomenological master equations with memory kernel always describe a non-Markovian quantum dynamics characterized by reverse flow of information? Is the integration over the past states of the system an unmistakable signature of non-Markovianity? We show by a counterexample that this is not always the case. We consider two commonly used phenomenological integro-differential master equations describing the dynamics of a spin 1/2 in a thermal bath. By using a recently introduced measure to quantify non-Markovianity [H.-P. Breuer, E.-M. Laine, and J. Piilo, Phys. Rev. Lett. 103, 210401 (2009)] we demonstrate that as far as the equations retain their physical sense, the key feature of non-Markovian behavior does not appear in the considered memory kernel master equations. Namely, there is no reverse flow of information from the environment to the open system. Therefore, the assumption that the integration over a memory kernel always leads to a non-Markovian dynamics turns out to be vulnerable to phenomenological approximations. Instead, the considered phenomenological equations are able to describe time-dependent and uni-directional information flow from the system to the reservoir associated to time-dependent Markovian processes.Comment: 5 pages, no figure

A simple trapped-ion architecture for high-fidelity Toffoli gates

We discuss a simple architecture for a quantum Toffoli gate implemented using three trapped ions. The gate, which in principle can be implemented with a single laser-induced operation, is effective under rather general conditions and is strikingly robust (within any experimentally realistic range of values) against dephasing, heating and random fluctuations of the Hamiltonian parameters. We provide a full characterization of the unitary and noise-affected gate using three-qubit quantum process tomography

Critical assessment of two-qubit post-Markovian master equations

A post-Markovian master equation has been recently proposed as a tool to describe the evolution of a system coupled to a memory-keeping environment [A. Shabani and D. A. Lidar, Phys. Rev. A 71, 020101 (R) (2005)]. For a single qubit affected by appropriately chosen environmental conditions, the corresponding dynamics is always legitimate and physical. Here we extend such situation to the case of two qubits, only one of which experiences the environmental effects. We show how, despite the innocence of such an extension, the introduction of the second qubit should be done cum grano salis to avoid consequences such as the breaking of the positivity of the associated dynamical map. This hints at the necessity of using care when adopting phenomenologically derived models for evolutions occurring outside the Markovian framework.Comment: 7 pages, 1 figure, RevTeX4. Close to published versio

Contractions of low-dimensional nilpotent Jordan algebras

In this paper we classify the laws of three-dimensional and four-dimensional nilpotent Jordan algebras over the field of complex numbers. We describe the irreducible components of their algebraic varieties and extend contractions and deformations among them. In particular, we prove that J2 and J3 are irreducible and that J4 is the union of the Zariski closures of two rigid Jordan algebras.Comment: 12 pages, 3 figure