Investigation of the Role of Elastic Unitarity in High-Energy Scattering: Gribov's Theorem and the Froissart Bound

We re-examine V. Gribov's theorem of 1960 according to which the total cross-section cannot approach a finite non-zero limit with, at the same time, a diffraction peak having a finite slope. We are very close to proving by an explicit counter-example that elastic unitarity in the elastic region is an essential ingredient of the proof. By analogy, we raise the question of the saturation of the Froissart-Martin bound, for which no examples incorporating elastic unitarity exist at the present time.Comment: 11 pages, 1 figures, latex with sproc.st

On the Stability Domain of Systems of Three Arbitrary Charges

We present results on the stability of quantum systems consisting of a negative charge $-q_1$ with mass $m_{1}$ and two positive charges $q_2$ and $q_3$, with masses $m_{2}$ and $m_{3}$, respectively. We show that, for given masses $m_{i}$, each instability domain is convex in the plane of the variables $(q_{1}/q_{2}, q_{1}/q_{3})$. A new proof is given of the instability of muonic ions $(\alpha, p, \mu^-)$. We then study stability in some critical regimes where $q_3\ll q_2$: stability is sometimes restricted to large values of some mass ratios; the behaviour of the stability frontier is established to leading order in $q_3/q_2$. Finally we present some conjectures about the shape of the stability domain, both for given masses and varying charges, and for given charges and varying masses.Comment: Latex, 24 pages, 14 figures (some in latex, some in .eps

The role of the state and the community in community participation: A case study

This study analyzes the principles and the practice of the concept of community participation. The purpose of research is to address the degree and manner of autonomy that can be exercised at the local community level and also what kind of participation should come from the state when communities are engaged with the state in a community participation process. The methodology of qualitative nature, is a case study of the Sudbury Better Beginnings, Better Futures Associations. An analysis of the public documents comparing the state and the Sudbury Association’s position on community participation principles is portrayed before performing an analysis on the implementation strategies used by the Sudbury Better Beginnings, Better Futures Association. The conceptual framework provides an argument for more direct democracy and addresses six concepts: community, community development, community organization, social development, adult education, and community economic development; which are used to delimit the concept of community participation. Two models of citizen participation (Arnstein, 1969; Bregha, 1973) are then used to gauge the level of true participation achieved by the Sudbury Better Beginnings, Better Futures model. In the discussion, the concept of “social relations” (Ng et al., 1990) is introduced to further complement the findings achieved with the conceptual framework of the study. The concept of social relations accentuates the importance of everyday work and life activities of community members as contributing factors important to the larger social, political and economic context of our society. Finally, arguments are presented in favour of the concept of communitarianism as a means to achieve more direct democracy in a partnership with the state

Structure development during polymer processing. Morphological and crystallographic textures in polyethylene blown films

La publication originale est disponible sur le site http://www.revue-metallurgie.orgInternational audienceThe crystallographic texture of a great number of polyethylene films manufactured by the film blowing process has been investigated by X-ray diffraction. Some films present a classical texture (c-axis in the machine direction), which can be interpreted using existing morphological models. Other exhibit an original texture (c-axis in the film thickness) and no satisfactory morphological model has been proposed until now

SCD: A 3 States Startle Copying Display to Manage Deleterious Effects of Extreme Emergency Situation.

The management of cognitive resources are central in the case of a decision-making process by pilots. We undertake a study involving Airbus 400M pilots and allowing to understand these mechanisms and to propose recommendations for the design of a tool to assist in the management of their cognitive resources. We find that in the most critical cases and under strong temporal pressure, the maintenance of control of the situation corresponds to a survival type behavior which alone can allow a return to the metarules (back to basics). Our display management proposal allows the pilot to maintain control of the situation regardless of his capabilities. It allows a phase of stabilization by a reduction of the stress, then a phase of soft recovery of the control and the management of the mission on larger spatiotemporal dimensions. Three modes of entry in the HMI are envisaged: spontaneous, proposed and on demand

Exhaust emissions of regulated and unregulated pollutants of passenger cars

Exhaust emissions of VOC speciation, aldehydes and other carbonyl compounds, polyaromatics and regulated pollutants are measured using a vehicle bench on a sample of passenger cars. 30 diesel and gasoline cars are tested, complying with ECE 1504 to Euro 3 emission standards, according to 10 real-world driving cycles based on European driving behaviour, with some of them adapted to vehicle size. The emission results of this large-scale measurement campaign show the influence of vehicle technology and driving behaviour on the emission of 100 individual pollutants. In addition, the results are discussed per VOC group and compared with other studies. The influence of the successive emission standards on the emission factors is very positive in most of cases. However, whereas hot CO2 is almost stable, diesel hot NOx, diesel hot and cold VOC, and the 6 most carcinogenic gasoline PAH have increased with standards. Diesel vehicles are less pollutant for CO, HC, CO2, VOC, but more pollutant for NOx and PAH. The distribution of VOC species per molecular family highlights the fact that monoaromatics make up the biggest share (~88 and 62 % resp. for gasoline and diesel vehicles). The second family is the alkanes which contribute resp. 8 and 9% of the total mass of measured VOC. The majority of volatile PAH is observed in the gaseous phase, but the least volatile and the carcinogenic PAH are adsorbed more in particulate phase

Multi-locus barcoding confirms the occurrence of Elegant Tern in Western Europe

We are very grateful to the following people who helped in various ways with sample collection: Jérome Fuchs and Eric Pasquet (National Museum of Natural History, Paris), Sharon M. Birks (Burke Museum of Naturel History of Seattle), Charlotte Francesiaz, Benjamin Vollot and Gilles Balança (Sandwich Tern, France), Charles Collins (Elegant Tern, USA), Arnaud Lenoble (Royal Tern, Guadeloupe), Lorien Pichegru (Crested Tern, South Africa), Abdulmaula Hamza (Lesser Crested Tern, Libya) and Clive Barlow (The Gambia). Marcio Efe and Eli Bridge helped with genotyping and shared unpublished sequences. We thank Juan Antonio Gómez for advice and Miguel Chardí and Francisco Javier García-Gans for field assistance in Valencia (Spain). Mathias Grandpierre (Société pour l’Etude et l’Aménagement de la Nature dans le Sud-Ouest) helped with fieldwork at the Banc d’Arguin (France). All the experiments comply with the current laws of the country in which they were performed.Peer reviewedPostprin

Low-energy potential scattering in two and three dimensions

Conditions are established for the existence of a scattering length and an effective range in the low-energy expansion of the S-wave phase-shift of a central potential in two and three dimensions. The behavior of the phase-shift as a function of the momentum is also derived for longer-range power-law potentials which do not fulfill these conditions.Comment: 19 pages, pdflatex, 3 figures, refs. added, typos corrected, to appear in JM

BRAIN-COMPUTER INTERFACE: COMPARISON OF TWO CONTROL MODES TO DRIVE A VIRTUAL ROBOT

A Brain-Computer Interface (BCI) is a system that enables communication and control that is not based on muscular movements, but on brain activity. Some of these systems are based on discrimination of different mental tasks; usually they match the number of mental tasks to the number of control commands. Previous research at the University of Málaga (UMABCI) have proposed a BCI system to freely control an external device, letting the subjects choose among several navigation commands using only one active mental task (versus any other mental activity). Although the navigation paradigm proposed in this system has been proved useful for continuous movements, if the user wants to move medium or large distances, he/she needs to keep the effort of the MI task in order to keep the command. In this way, the aim of this work was to test a navigation paradigm based on the brain-switch mode for ‘forward’ command. In this mode, the subjects used the mental task to switch their state on /off: they stopped if they were moving forward and vice versa. Initially, twelve healthy and untrained subjects participated in this study, but due to a lack of control in previous session, only four subjects participated in the experiment, in which they had to control a virtual robot using two paradigms: one based on continuous mode and another based on switch mode. Preliminary results show that both paradigms can be used to navigate through virtual environments, although with the first one the times needed to complete a path were notably lower