A System of Interaction and Structure

This paper introduces a logical system, called BV, which extends multiplicative linear logic by a non-commutative self-dual logical operator. This extension is particularly challenging for the sequent calculus, and so far it is not achieved therein. It becomes very natural in a new formalism, called the calculus of structures, which is the main contribution of this work. Structures are formulae submitted to certain equational laws typical of sequents. The calculus of structures is obtained by generalising the sequent calculus in such a way that a new top-down symmetry of derivations is observed, and it employs inference rules that rewrite inside structures at any depth. These properties, in addition to allow the design of BV, yield a modular proof of cut elimination.Comment: This is the authoritative version of the article, with readable pictures, in colour, also available at . (The published version contains errors introduced by the editorial processing.) Web site for Deep Inference and the Calculus of Structures at <http://alessio.guglielmi.name/res/cos

Jet propulsion without inertia

A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies, and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented, and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e. jetting) surfaces are considered, and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate, and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria

The determinants of Teachers’ Wellbeing: the mediating role of Mental Fatigue

In recent years, many studies have focused on the determinants and consequences of teacher stress. One of the most recent theoretical models concerning stress is the Job Demands-Resources (JD-R) model. This study examines one process – namely the energetic process – which supposes that high job demands exhaust employees’ mental and physical resources and therefore cause ill health. Particularly, this study examines the mediating role of mental fatigue between three job demands of teachers (workload, inequity and work/family confl ict) and three consequences of stress: psychological and physical symptoms and work satisfaction. An Italian version of the selfreport Questionnaire for Psychosocial Work Environment and Stress (PWSQ) was administered to 697 teachers belonging to a random sample of 17 school organizations. The results showed that mental fatigue has a mediating role in the relationship between work/family confl ict and the three outcomes considered, namely psychological and physical symptoms, and work satisfaction. This study has an important implication for intervention strategy because mental fatigue is a pre-strain condition which arises before more intense outcomes, such as stress-related diseases occur. Identifi cation of this condition allows prevention of the consequences of stress

A new search for anomalous neutrino oscillations at the CERN-PS

The LSND experiment has observed a 3.8 sigma excess of anti-nu_e events from an anti-nu_mu beam coming from pions at rest. If confirmed, the LSND anomaly would imply new physics beyond the standard model, presumably in the form of some additional sterile neutrinos. The MiniBooNE experiment at FNAL-Booster has further searched for the LSND anomaly. Above 475 MeV, the nu_e result is excluding the LSND anomaly to about 1.6 sigma but it introduces an unexplained, new 3.0 sigma anomaly at lower energies, down to 200 MeV. The nu_e data have so far an insufficient statistics to be conclusive with LSND's anti-nu_e. The present proposal at the CERN-PS is based on two strictly identical LAr-TPC detectors in the near and far positions, respectively at 127 and 850 m from the neutrino (or antineutrino) target and focussing horn, observing the electron-neutrino signal. This project will benefit from the already developed technology of ICARUS T600, well tested on surface in Pavia, without the need of any major R&D activity and without the added problems of an underground experiment (CNGS-2). The superior quality of the Liquid Argon imaging TPC and its unique electron - pi-zero discrimination allow full rejection of the NC background, without efficiency loss for electron neutrino detection. In two years of exposure, the far detector mass of 600 tons and a reasonable utilization of the CERN-PS with the refurbished previous TT7 beam line will allow to collect about 10^6 charged current events, largely adequate to settle definitely the LSND anomaly.Comment: 23 pages, 17 figures, added watermark, better referencin

Operation of a LAr-TPC equipped with a multilayer LEM charge readout

A novel detector for the ionization signal in a single phase LAr-TPC, based on the adoption of a multilayer Large Electron Multiplier (LEM) replacing the traditional anodic wire arrays, has been experimented in the ICARINO test facility at the INFN Laboratories in Legnaro. Cosmic muon tracks were detected allowing the measurement of energy deposition and a first determination of the signal to noise ratio. The analysis of the recorded events demonstrated the 3D reconstruction capability of ionizing events in this device in liquid Argon, collecting a fraction of about 90% of the ionization signal with signal to noise ratio similar to that measured with more traditional wire chambersComment: 9 pages, 7 Figure

Coping with negative stereotypes toward older workers: Organizational and work-related outcomes

The current study aims to test a moderated-mediation model in which occupational selfefficacy determines the indirect effect of negative stereotypes about older workers in the organization both on psychological engagement in the work domain and on attitudes toward development opportunities through identification with the company. The survey involved 1,501 Italian subjects aged over 50 who were employed by a major large-scale retailer. Consistently with the Social Identity Theory and the Social Exchange Theory, results showed that the perception of negative stereotypes about older workers in the organization is associated with low identification with the company and, subsequently, with poor psychological engagement in the work domain and with attitudes indicating very little interest in development opportunities. In addition, this association was found to be stronger in older workers with higher and medium levels of occupational selfefficacy. These findings suggest that organizations should discourage the dissemination of negative stereotypes about older workers in the workplace because they may lead to older workers' disengagement from the work domain and their loss of interest in development opportunities

Analysis of the micro to macro response of clays to compression

An investigation of clay microstructure and its evolution under 1D and isotropic compression is presented for different clays. Data from the literature are compared to original results on two Italian clays, obtained using SEM, image processing, MIP and on-purpose swelling tests. The effects of composition and loading history on clay microstructure, as well as its changes along the compression path (pre- and post-gross-yielding) are analysed and a conceptual model of microstructure evolution is proposed for the clays under study. NC clays at early virgin compression, either natural or reconstituted, are found to possess an open fabric of random-low orientation, complying with a prevailing inter-aggregate and a smaller intra-aggregate porosity, whose size and distribution depend on composition. Under 1D compression, either in the field or in the laboratory, the inter-aggregate porosity is lost, at a rate dependent on composition and loading history, and the dominant intra-aggregate micro-pore is progressively reduced. Accordingly, perfectly oriented stacks of domains are recognised which, though, embed preserved random particle arrangements even at large pressures, resulting in an increase of average orientation up to the reach of a steady orientation degree. Isotropic compression causes faster microstructure evolution, although large pressures are required to change 1D-induced fabric orientation.Peer ReviewedPostprint (author's final draft

Characterisation of the multi-scale fabric features of high plasticity clays

An investigation of the microstructural features of a high-plasticity clay, in both its natural conditions and reconstituted in the laboratory, is described. Scanning electron microscopy is used here to characterise the fabric at different magnifications, while image processing of the micrographs delivers a quantitative assessment of the fabric orientation. The results of energy-dispersive X-ray spectroscopy and swelling tests, as reported in a previous study by the authors, are used to characterise the bonding nature and strength, as well as mercury intrusion porosimetry to investigate clay porosimetry. Despite their identical composition, the natural and the reconstituted clay have experienced different deposition and loading history, generating different microstructural features that are shown to underlie their differences in state. For both clays, one-dimensional (1D) compression to medium–high pressures is seen to determine a well-oriented medium magnification fabric. However, larger-scale observations and the corresponding image processing results reveal non-uniform local fabric features, hence making fabric characterisation dependent on the scale of analysis and bringing about the issue of identifying the clay micro-scale representative element volume relating to the clay macro-behaviour. The micro-REV is identified for the clays under study and its connection with the macro-behaviour characterised. The microstructural evolution induced by 1D compression to very high pressures is shown to concern mainly the clay porosity and porosimetry, the fabric orientation being steady, thus explaining the isotropic hardening observed in laboratory tests.Peer ReviewedPostprint (author's final draft

On the excitation of magnetic signals by Love waves

The polarization method for recognition of seismomagnetic waves against a noise background is presented. The method is applied to detection of magnetic oscillations accompanying the propagation of surface Love wave after a strong earthquake. A specific property of the Love waves is that theoretically the Tolman-Stewart effect is alone responsible for the magnetic field that penetrates into the Earth's surface. Data from the Mondy Magnetic Observatory and the Talaya Seismic Station suggest that the arrival time, duration, period,and polarization of magnetic signals conform with the idea of generation of alternating electric currents due to fluid vibrations in pores and fractures of rocks under the action of the inertial force associated with the Love wave propagation