7,314 research outputs found

    The PANDA experiment: Antiproton physics at FAIR

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    The new Facility for Antiproton and Ion Research (FAIR), under construction at the GSI laboratory at Darmstadt, in a few years will make available, among different types of beams, even antiproton beams with unique features. Through a High Energy Storage Ring (HESR) for antiprotons, an antiproton beam will be available in a momentum range from 1.5 to 15 GeV/c, which will interact on a hydrogen target. The products of the interaction, including hadronic systems with strangeness and/or charm, will be detected with the PANDA magnetic spectrometer (antiProton ANnihilation at DArmstadt), and the spectroscopic analysis will allow a detailed investigation on a number of open problems of the hadronic physics, as the quark confinement, the existence of non-conventional meson states (so-called glueballs and hybrids), the structure of hadrons and of the strong interaction, with particular attention to charmonium spectroscopy. An overview of the scientific program of PANDA and the current status of the project will be presented

    A note on drastic product logic

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    The drastic product ∗D*_D is known to be the smallest tt-norm, since x∗Dy=0x *_D y = 0 whenever x,y<1x, y < 1. This tt-norm is not left-continuous, and hence it does not admit a residuum. So, there are no drastic product tt-norm based many-valued logics, in the sense of [EG01]. However, if we renounce standard completeness, we can study the logic whose semantics is provided by those MTL chains whose monoidal operation is the drastic product. This logic is called S3MTL{\rm S}_{3}{\rm MTL} in [NOG06]. In this note we justify the study of this logic, which we rechristen DP (for drastic product), by means of some interesting properties relating DP and its algebraic semantics to a weakened law of excluded middle, to the Δ\Delta projection operator and to discriminator varieties. We shall show that the category of finite DP-algebras is dually equivalent to a category whose objects are multisets of finite chains. This duality allows us to classify all axiomatic extensions of DP, and to compute the free finitely generated DP-algebras.Comment: 11 pages, 3 figure

    The acceleration of metastases after tumor removal and the paradoxical phenomenon of concomitant tumor resistance

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    Although surgical extirpation of tumors is usually clinically recommended, tumor removal may entail an undesired side effect: the risk of accelerating the growth of metastases. This effect may account for the relatively modest survival benefits observed when surgery is accomplished after tumor cells have already disseminated to distant anatomical sites even when tumor removal is combined with chemotherapy or immunotherapy. Although different mechanisms could contribute to the enhancement of residual tumor growth after tumor removal, probably a main effect is associated with the withdrawing of an inhibitory effect generated, by certain circumstances, by the primary tumor on its own metastases. This inhibitory effect is a particular case of a more general and paradoxical phenomenon known as concomitant tumor resistance (CR) in which a tumor-bearing host inhibits or retards the growth of secondary tumor implants despite the fact that the primary tumor grows progressively. In this essay we especially focus on the last investigations of our laboratory concerningthe importance of tyrosine isomers as mediators of the phenomenon of CR and on their capacity to inhibit established metastases. Taking into account that metastases are considered the main problem in cancer pathology, our investigations aimed to elucidate the molecular basis of the phenomenon of CR might stimulate the design of new and less harmful means of managing malignant diseases, especially by controlling the growth of metastases after the removal of a primary tumor, or after other injuries or stressors that have been claimed to promote the escape of metastases from dormancy.Fil: Montagna, Daniela Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Chiarella, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Meiss, Roberto P.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Ruggiero, Raul Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentin

    Timescales of mingling in shallow magmatic reservoirs

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    Arrival of magma from depth into shallow reservoirs has been documented as one of the possible processes leading to eruption. Magma intruding and rising to the surface interacts with the already emplaced, degassed magmas residing at shallower depths, leaving chemical signatures in the erupted products.We performed two-dimensional numerical simulations of the arrival of gas- rich magmas into shallow reservoirs. We solve the fluid dynamics for the two interacting magmas, evaluating the space–time evolution of the physical properties of the mixture. Convection and mingling develop quickly into the chamber and feeding conduit/dyke, leading on longer timescales to a density stratification with the lighter, gas-richer magma, mixed with different proportions of the resident magma, rising to the top of the chamber due to buoyancy. Over timescales of hours, the magmas in the reservoir appear to have mingled throughout, and convective patterns become harder to identify. Our simulations have been performed changing the geometry of the shallow reservoir and the gas content of the initial end-member magmas. Horizontally elongated magma chambers, as well as higher density contrasts between the two magmas, cause faster ascent velocities and also increase the mixing efficiency

    Stable non-standard imprecise probabilities

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    Stability arises as the consistency criterion in a betting interpretation for hyperreal imprecise previsions, that is imprecise previsions (and probabilities) which may take infinitesimal values. The purpose of this work is to extend the notion of stable coherence introduced in [8] to conditional hyperreal imprecise probabilities. Our investigation extends the de Finetti-Walley operational characterisation of (imprecise) prevision to conditioning on events which are considered "practically impossible" but not "logically impossible"

    ORIGIN OF LIGHT SCATTERING FROM DISORDERED SYSTEMS

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    Anelastic light scattering is computed numerically for model disordered systems (linear chains and 2-dimensional site and bond percolators), with and without electrical disorder. A detailed analysis of the vibrational modes and of their Raman activity evidences that two extreme mechanisms for scattering may be singled out. One of these resembles scattering from finite size systems, while the other mechanisms originates from spatial fluctuations of the polarizability and is such that modes in even small frequency intervals may have very different Raman activities. As a consequence, the average coupling coefficient C(ω)C(\omega) is the variance of a zero-average quantity. Our analysis shows that for both linear chains and 2-dimensional percolators the second mechanism dominates over the first, and therefore Raman scattering from disordered systems is essentially due to spatial fluctuations.Comment: 12 pages, Latex, 7 figures available on request

    Knowledge, attitudes, and behavior concerning dental trauma among parents of children attending primary school

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    BACKGROUND: Traumatic dental injuries occur frequently in children and adolescents. The purpose of the present study is to examine the levels of knowledge and behaviors regarding dental trauma among parents of children attending primary schools in the Apulia region of Italy. METHODS: The study was carried out using an anonymous questionnaire with closed answers distributed to 2,775 parents who were enrolled based on the entire regional school population. Analyses were conducted using the PROC CORRESP (procedure to perform multiple correspondence analysis) and PROC FASTCLUS (procedure to perform cluster analysis). Statistical significance was set at p-value <0.05. RESULTS: A total 15.5% of the sample reported that their children had experienced dental trauma. Overall, 53.8% of respondents stated that they knew what to do in cases of dental injury. Regarding the time limit within which it is possible to usefully intervene for dental trauma, 56.8% of respondents indicated "within 30 minutes". Of the total sample, 56.5% knew how to preserve a displaced tooth. A total 62.9% of parents felt it was appropriate for their children to use dental guards during sports activities. The multivariate analysis showed that wrong knowledge are distributed among all kinds of subject. Parents with previous experience of dental trauma referred right behaviours, instead weak knowledge and wrong behaviours are associated with parents that easily worried for dental events. CONCLUSIONS: This study showed that most parents reported no experience of dental trauma in their children, and half of them did not know what to do in case of traumatic dental injury and they would intervene within 30 minutes, suggesting that dental trauma may trigger panic. However, they did not have the information needed to best assist the affected child. Motivating parents to assume a preventive approach towards dental trauma may produce positive changes that would result an increase of long-term health benefits among both parents and children
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