A phenomenological analysis of antiproton interactions at low energies

We present an optical potential analysis of the antiproton-proton interactions at low energies. Our optical potential is purely phenomenological, and has been parametrized on data recently obtained by the Obelix Collaboration at momenta below 180 MeV/c. It reasonably fits annihilation and elastic data below 600 MeV/c, and allows us for an evaluation of the elastic cross section and rho-parameter down to zero kinetic energy. Moreover we show that the mechanism that depresses antiproton-nucleus annihilation cross sections at low energies is present in antiproton-proton interactions too.Comment: 10 pages, 4 figure

Antiproton annihilation on light nuclei at very low energies

The recent experimental data obtained by the OBELIX group on $\bar{p}$D and $\bar{p}^4$He total annihilation cross sections are analyzed. The combined analysis of these data with existing antiprotonic atom data allows, for the first time, the imaginary parts of the S-wave scattering lengths for the two nuclei to be extracted. The obtained values are: $Im a^{sc}_0 = [- 0.62 \pm 0.02 ({stat}) \pm 0.04 ({sys})] fm$ for $\bar{p}$D and $Im a^{sc}_0 = [- 0.36\pm 0.03({stat})^{+0.19}_{-0.11}({sys})] fm$ for $\bar{p}^4$He. This analysis indicates an unexpected behaviour of the imaginary part of the $\bar{p}$-nucleus S-wave scattering length as a function of the atomic weight A: $|Im a^{sc}_0|$ ($\bar{p}$p) > $|Im a^{sc}_0|$ ($\bar{p}$D) > $|Im a^{sc}_0|$ ($\bar{p}^4$He).Comment: 13 pages, 5 figure

Coulomb corrections to low energy antiproton annihilation cross sections on protons and nuclei

We calculate, in a systematic way, the enhancement effect on antiproton-proton and antiproton-nucleus annihilation cross sections at low energy due to the initial state electrostatic interaction between the projectile and the target nucleus. This calculation is aimed at future comparisons between antineutron and antiproton annihilation rates on different targets, for the extraction of pure isospin channels.Comment: 18 pages, 4 figures (latex format

Historical building stability monitoring by means of a cosmic ray tracking system

Cosmic ray radiation is mostly composed, at sea level, by high energy muons, which are highly penetrating particles capable of crossing kilometers of rock. The ubiquitous and steady presence at the Earth's surface and the high penetration capability have motivated the use of cosmic ray radiation also in fields beyond particle physics, from geology, archeology, speleology to industrial applications and homeland security. In particular, in recent years, the novel technique of muon tomography has been proposed, with the aim of performing non invasive inspection of large non accessible volumes, material atomic number Z and density discrimination, and three dimension image reconstruction of the inspected volume. In the present paper, after a short recall of the physical principles and mathematical formalism on which muon tomography is based, a number of examples of application of the novel technique in industry and homeland security issues is given. Moreover, a new application of cosmic rays detection techniques in the field of civil engineering is proposed. The aim is the monitoring of the stability of large structures, in particular the static monitoring of historical buildings, where conservation constraints are more severe and the time evolution of the deformation phenomena under study may be of the order of months or years. The new technique may be seen, in some way, as the reverse problem of muon tomography. As a significant case study, the monitoring of the wooden vaulted roof of the Palazzo della Loggia in the town of Brescia, in Italy, has been considered. The feasibility as well as the performances and limitations of a monitoring system based on cosmic ray tracking have been studied by Monte Carlo simulation and discussed in comparison with more traditional monitoring systems

Evaluating a co-creation model for social businesses: The case of ‘Linhas sobre rodas’

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and EconomicsThe following research is a critical evaluation of „Linhas sobre Rodas‟ co-creation process, since during my internship, from August to November 2012, I had the opportunity of directly and daily collaborate with the entities involved on the operationalization and implementation of this social business. The research analyses the key success factors of the „Linhas sobre Rodas‟ model during its initial stage, focusing on the stakeholders‟ relations and on the strategic alliance between the two co-creators. Through the evaluation of both strengths and weaknesses of this case study, the research provides recommendations and findings for similar cases

“A Leap of Faith”: Student to Professional

This qualitative, phenomenological study sought to answer the question: How do new graduates view their baccalaureate educational experiences in relation to their transition to professional practice? Eight new graduate nurses from a private nursing school in the western United States participated in this study. Participants wrote reflections describing their transition from student role to professional nurse and reviewed these reflections with the researcher at the end of face-to-face interviews. In-depth interviews using open-ended questions were conducted, recorded, and transcribed by the researcher. The results of the interview and reflections were analyzed by the researcher using Colaizzi’s (1978) method to identify the recurring themes and member checking with the participants to help validate the results. Additional validation strategies included writing rich, thick descriptions; triangulation using interviews, reflections, and field notes; clarification of researcher bias; and peer debriefing. Reliability was enhanced by the researcher using a quality digital audiotape recorder, transcribing the interviews, and utilizing an audit trail during data collection and analysis. Five themes were identified in this study: (a) figuring it out, (b) the learning process, (c) influential people, (d) where you practice matters, and (e) questioning preparation. When describing their transition experiences and retention in both their reflections and interviews, the participants identified how essential their nursing education experiences were in laying the foundation for building their professional practice. This study provided insight into transition and retention experiences as it is the only qualitative study that investigated the entire educational experience and utilized open-ended interviews and reflections. The theory of transition was used to inform the study. The participants’ journeys from student role to professional nurse were unique because their educational and new graduate orientation experiences varied but, ultimately, each participant referenced education in the interview and reflection. The interviews took place in cafés and coffee shops per participants’ request and participants identified issues supporting working night shifts as a new graduate nurse. Results supported the appropriateness of using Meleis’ (2010) theory of transition to provide insight into baccalaureate nursing students’ transition from a student role to professional nurse. Findings from the study provided the rationale for recommendations for nurse educators that included retaining or implementing precepted practicum experiences, retaining or enhancing high quality clinical placements, addressing incivility on nursing units to support both students and staff nurses, supporting and educating preceptors in the clinical setting, providing opportunities for nursing students to care for critically ill or complex patients, providing opportunities for preceptors and clinical faculty to allow students and new graduate nurses to become more independent in providing patient care while continuing to be a resource to insure patient safety, and supporting nurses of all generations in their educational and work place needs to encourage retention. Students take a leap of faith when starting a nursing program and entering practice. They rely on nursing education to provide the necessary foundational knowledge and experiences to support their transition from a student role to professional nurse and to support their retention in their first nursing roles as well as the nursing profession. Key Words: transition to practice, retention, phenomenology, transition theory, preparation for practic

Remarks on an experimental study of the formation and decay of the p̄He+ atomcule

Abstract Recently, data on p annihilation at rest on gaseous 4He at 3 bar, collected by the Obelix Experiment at LEAR, were used to infer information on the formation and decay of the p He + atomcule. The straightforward interpretation of these data in terms of significant physical signals does not seem justified in the light of previous experimental information published by the Obelix Collaboration

Pistil transcriptome analysis to disclose genes and gene products related to aposporous apomixis in Hypericum perforatum L.

Unlike sexual reproduction, apomixis encompasses a number of reproductive strategies,which permit maternal genome inheritance without genetic recombination and syngamy. The key biological features of apomixis are the circumvention of meiosis (i.e., apomeiosis),the differentiation of unreduced embryo sacs and egg cells, and their autonomous development in functional embryos through parthenogenesis, and the formation of viable endosperm either via fertilization-independent means or following fertilization with a sperm cell. Despite the importance of apomixis for breeding of crop plants and although much research has been conducted to study this process, the genetic control of apomixis is still not well understood. Hypericum perforatum is becoming an attractive model system for the study of aposporous apomixis. Here we report results from a global gene expression analysis of H. perforatum pistils collected from sexual and aposporous plant accessions for the purpose of identifying genes, biological processes and molecular functions associated with the aposporous apomixis pathway. Across two developmental stages corresponding to the expression of aposporous apomeiosis and parthenogenesis in ovules, a total of 224 and 973 unigenes were found to be significantly up- and down-regulated with a fold change >= 2 in at least one comparison, respectively.Differentially expressed genes were enriched for multiple gene ontology (GO) terms,including cell cycle, DNA metabolic process, and single-organism cellular process. For molecular functions, the highest scores were recorded for GO terms associated withDNA binding, DNA (cytosine-5-)-methyltransferase activity and heterocyclic compound binding. As deregulation of single components of the sexual developmental pathway is believed to be a trigger of the apomictic reproductive program, all genes involved in sporogenesis, gametogenesis and response to hormonal stimuli were analyzed in great detail. Overall, our data suggest that phenotypic expression of apospory is concomitant with the modulation of key genes involved in the sexual reproductive pathway. Furthermore, based on gene annotation and co-expression, we underline a putative role of hormones and key actors playing in the RNA-directed DNA methylation pathway in regulating the developmental changes occurring during aposporous apomixis in H. perforatum