Entanglement, Superselection Rules and Supersymmetric Quantum Mechanics

In this paper we show that the energy eigenstates of supersymmetric quantum mechanics (SUSYQM) with non definite "fermion" number are entangled states. They are "physical states" of the model provided that observables with odd number of spin variables are allowed in the theory like it happens in the Jaynes-Cummings model. Those states generalize the so called "spin spring" states of the Jaynes-Cummings model which have played an important role in the study of entanglement.Comment: 2 words added in the title, a section (IV) added in the text, a new author joined the projec

The impact of ocean acidification on the skeletal ossification in herring larvae (Clupea harengus, L.)

In the era of pervasive mobile computing, human encounters can be leveraged to enable new forms of social interactions mediated by the personal devices of individuals. In this framework, emerging needs, such as content dissemination, social discovery and question&answering, advocate the raising of novel communication paradigms where the binding content-recipients is not provided by the sender (in the classical IP addressing style), but directly executed by specific recipients with interest on it. This allows tagged contents to be freely advertised on the network according to a content-driven approach; human encounters drive the information towards potential recipients that extract it from the stream when content type and personal interest match. This very active research area has recently produced a few preliminary solutions to this networking problem; they inherently confine message delivery inside a specific location and/or community. This covers only a part of users needs, as emerging from everyday life experience and recent studies in human sciences. This paper proposes a novel communication protocol, named InterestCast, or I Cast, solving the problem for a wide range of social scenarios and applying to a delay tolerant ad hoc network whose nodes are the personal device of moving individuals, possibly interacting with fixed road-side devices. The protocol is able to chase users interests decoupling content tags from locations and social communities. The main advantages the proposal achieves are: it ensures remarkable performance results; it is simple and, thus, it is feasible and keeps computational and networking costs low; it preserves users privacy.erant ad hoc network whose nodes are the personal device of moving individuals, possibly interacting with fixed road-side devices. The protocol is able to chase users interests decoupling content tags from locations and social communities. The main advantages the proposal achieves are: it ensures remarkable performance results; it is simple and, thus, it is feasible and keeps computational and networking costs low; it preserves users privacy

Coupling three-dimensional peridynamics and high-order one-dimensional finite elements based on local elasticity for the linear static analysis of solid beams and thin-walled reinforced structures

Peridynamics is a nonlocal theory which has been successfully applied to solid mechanics and crack propagation problems over the last decade. This methodology, however, may lead to large computational calculations which can soon become intractable for many problems of practical interest. In this context, a technique to couple—in a global/local sense–three-dimensional peridynamics with one-dimensional high-order finite elements based on classical elasticity is proposed. The refined finite elements employed in this work are based on the well-established Carrera Unified Formulation, which the previous literature has demonstrated to provide structural formulations with unprecedented accuracy and optimized computational efficiency. The coupling is realized by using Lagrange multipliers that guarantee versatility and physical consistency as shown by the numerical results, including the linear static analyses of solid and thin-walled beams as well as of a reinforced panel of aeronautic interest

Component-Wise Method Applied to Static and Dynamic Analysis of Reinforced Structures with Applications to Aerospace, Civil Engineering and Marine Constructions

In this work, an advanced formulation for the analysis of multi-component structures is presented. By employing the Carrera Unified Formulation (CUF), one-dimensional theories of structures are unified and written in a compact form by using fundamental nuclei. The principle of virtual displacement is then used to write the governing equations and the related finite element arrays. Classical one-dimensional shape functions are utilized to discretize the problem along the beam axis and to deal with complex geometries and loadings. Thanks to CUF, various one-dimensional beam theories are included within the same hierarchical finite element. Particular attention is paid to the Component-Wise (CW) approach. CW models are generated by developing beam theories based on Lagrange polynomial expansions of the generalized displacements. The enhanced capabilities of the present CW models when applied to the analysis of short beams, thin-walled structures and multi-component constructions are widely discussed

Detection of interstellar H_2D^+ emission

We report the detection of the 1_{10}-1_{11} ground state transition of ortho-H_2D^+ at 372.421 GHz in emission from the young stellar object NGC 1333 IRAS 4A. Detailed excitation models with a power-law temperature and density structure yield a beam-averaged H_2D^+ abundance of 3 x 10^{-12} with an uncertainty of a factor of two. The line was not detected toward W 33A, GL 2591, and NGC 2264 IRS, in the latter source at a level which is 3-8 times lower than previous observations. The H_2D^+ data provide direct evidence in support of low-temperature chemical models in which H_2D^+ is enhanced by the reaction of H_3^+ and HD. The H_2D^+ enhancement toward NGC 1333 IRAS 4A is also reflected in the high DCO^+/HCO^+ abundance ratio. Simultaneous observations of the N_2H^+ 4-3 line show that its abundance is about 50-100 times lower in NGC 1333 IRAS 4A than in the other sources, suggesting significant depletion of N_2. The N_2H^+ data provide independent lower limits on the H_3^+ abundance which are consistent with the abundances derived from H_2D^+. The corresponding limits on the H_3^+$ column density agree with recent near-infrared absorption measurements of H_3^+ toward W 33A and GL 2591.Comment: Standard AAS LaTeX format (15 pages + 2 figures

Large-deflection and post-buckling analyses of laminated composite beams by Carrera Unified Formulation

The Carrera Unified Formulation (CUF) was recently extended to deal with the geometric nonlinear analysis of solid cross-section and thin-walled metallic beams (Pagani and Carrera, 2017). The promising results provided enough confidence for exploring the capabilities of that methodology when dealing with large displacements and post-buckling response of composite laminated beams, which is the subject of the present work. Accordingly, by employing CUF, governing nonlinear equations of low- to higher-order beam theories for laminated beams are expressed in this paper as degenerated cases of the three-dimensional elasticity equilibrium via an appropriate index notation. In detail, although the provided equations are valid for any one-dimensional structural theory in a unified sense, layer-wise kinematics are employed in this paper through the use of Lagrange polynomial expansions of the primary mechanical variables. The principle of virtual work and a finite element approximation are used to formulate the governing equations in a total Lagrangian manner, whereas a Newton–Raphson linearization scheme along with a path-following method based on the arc-length constraint is employed to solve the geometrically nonlinear problem. Several numerical assessments are proposed, including post-buckling of symmetric cross-ply beams and large displacement analysis of asymmetric laminates under flexural and compression loadings