4,670 research outputs found

    Multiplicity dependence of correlation functions in \bar{p}p reactions at sqrt(s) = 630 GeV

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    Discussions about Bose-Einstein correlations between decay products of coproduced W-bosons again raise the question about the behaviour of correlations if several strings are produced. This is studied by the multiplicity dependence of correlation functions of particle pairs with like-sign and opposite-sign charge in \bar{p}p reactions at sqrt{s} = 630 GeV.Comment: 11 pages latex, 4 figs, includes elsart.cls, submitted to Phys Lett

    WHITE‐CROWNED MANAKIN (DIXIPHIA PIPRA) USE OF SPACE IN THE ECUADORIAN AMAZON

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    Abstract ∙ Animal patterns of space use have fundamental consequences for ecological processes such as animal‐ mediated seed dispersal. This study examines the use of space of an understory frugivore: the White‐crowned Manakin (Dixiphia pipra) during the non‐breeding season at Tiputini Biodiversity Station in Ecuador. We radio‐tracked seven individuals of different sexes and ages. We found that White‐crowned Manakins have relatively small home ranges varying from 1.19 to 5.73 ha. The home ranges of male juveniles (2.25 ± 0.62 SE) were larger than that of the adult males (1.20 ± 0.01 SE), but smaller than those of females (4.27 ± 0.77 SE). Females and second‐year males were found to perform more long distance flights outside their core home range than hatch‐year or adult males. These movement differences suggest that they disperse seeds longer distances and more evenly across their home range. Adult and hatch‐year males appear to perform more short distance seed dispersal events. We argue that these contributions are complementary, and that White‐crowned Manakins are key dispersal agents that have a significantly influence in the structure and composition of understory plant communities in the Amazon rainforest.Resumen ∙ Uso de espacio del SaltarĂ­n Coroniblanco (Dixiphia pipra) en la AmazonĂ­a Ecuatoriana Los patrones de uso espacial utilizados por animales tienen consecuencias fundamentales en procesos ecolĂłgicos, tales como la dispersiĂłn de semillas. Este estudio examina el uso espacial de una especie frugĂ­vora de sotobosque: el SaltarĂ­n Coroniblanco (Dixiphia pipra) durante el ciclo no‐reproductivo en la EstaciĂłn de Biodiversidad de Tiputini en Ecuador. Seguimos por radio telemetrĂ­a a siete individuos de diferentes sexos y edades. Encontramos que el SaltarĂ­n Coroniblanco tiene un rango de hogar relativamente pequeño, variando entre 1,19 a 5,73 ha. El rango de hogar de los machos juveniles (2,25 ± 0,62 EE) es mĂĄs grande que el de los machos adultos (1,20 ± 0,01 EE), pero mĂĄs pequeño que el de las hembras (4,27 ± 0,77 EE). El estudio encontrĂł que las hembras y los machos de segundo año realizaron vuelos mĂĄs largos fuera del nĂșcleo de su rango de hogar, comparado con machos juveniles del año o machos adultos. Estas diferencias sugieren que podrĂ­an dispersar semillas a mayores distancias y de manera mĂĄs homogĂ©nea a lo largo de su rango de hogar. Los machos adultos y los juveniles del año parecen llevar a cabo eventos de dispersiĂłn de semillas a distancias mĂĄs cortas. Nosotros argumentamos que estas contribuciones son complementarias y que los Saltarines Coroniblancos son agentes de dispersiĂłn claves, influenciando considerablemente la estructura y la composiciĂłn de las comunidades de plantas del sotobosque en el bosque tropical lluvioso de la AmazonĂ­a Ecuatoriana.

    Factorial Moments of Continuous Order

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    The normalized factorial moments FqF_q are continued to noninteger values of the order qq, satisfying the condition that the statistical fluctuations remain filtered out. That is, for Poisson distribution Fq=1F_q = 1 for all qq. The continuation procedure is designed with phenomenology and data analysis in mind. Examples are given to show how FqF_q can be obtained for positive and negative values of qq. With qq being continuous, multifractal analysis is made possible for multiplicity distributions that arise from self-similar dynamics. A step-by-step procedure of the method is summarized in the conclusion.Comment: 15 pages + 9 figures (figures available upon request), Late

    Bounds for Bose-Einstein Correlation Functions

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    Bounds for the correlation functions of identical bosons are discussed for the general case of a Gaussian density matrix. In particular, for a purely chaotic system the two-particle correlation function must always be greater than one. On the other hand, in the presence of a coherent component the correlation function may take values below unity. The experimental situation is briefly discussed.Comment: 7 pages, LaTeX, DMR-THEP-93-5/

    A sensitive test for models of Bose-Einstein correlations

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    Accurate and sensitive measurements of higher order cumulants open up new approaches to pion interferometry. It is now possible to test whether a given theoretical prediction can consistently match cumulants of both second and third order. Our consistency test utilizes a new technique combining theoretically predicted functions with experimentally determined weights in a quasi-Monte Carlo approach. Testing a general quantum statistics-based framework of Bose-Einstein correlations with this technique, we find that predictions for third order cumulants differ significantly from UA1 data. This discrepancy may point the way to more detailed dynamical information.Comment: 5 pages, 2 figures, revte

    A Color Mutation Model of Soft Interaction in High Energy Hadronic Collisions

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    A comprehensive model, called ECOMB, is proposed to describe multiparticle production by soft interaction. It incorporates the eikonal formalism, parton model, color mutation, branching and recombination. The physics is conceptually opposite to the dynamics that underlies the fragmentation of a string. The partons are present initially in a hadronic collision; they form a single, large, color-neutral cluster until color mutation of the quarks leads to a fission of the cluster into two color-neutral subclusters. The mutation and branching processes continue until only qqˉq\bar q pairs are left in each small cluster. The model contains self-similar dynamics and exhibits scaling behavior in the factorial moments. It can satisfactorily reproduce the intermittency data that no other model has been able to fit.Comment: 24 pages including 11 figures in revtex epsf styl

    Multi-boson effects and the normalization of the two-pion correlation function

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    The two-pion correlation function can be defined as a ratio of either the measured momentum distributions or the normalized momentum space probabilities. We show that the first alternative avoids certain ambiguities since then the normalization of the two-pion correlator contains important information on the multiplicity distribution of the event ensemble which is lost in the second alternative. We illustrate this explicitly for specific classes of event ensembles.Comment: 6 pages, three figures,submit to PR

    90-yttrium-ibritumomab tiuxetan as first-line treatment for follicular lymphoma: updated efficacy and safety results at an extended median follow-up of 9.6 years

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    Radioimmunotherapy with 90-yttrium-ibritumomab tiuxetan (90Y-IT) as first-line treatment in patients with follicular lymphoma (FL) demonstrated promising results with a complete remission (CR) rate of 56% and a median progression-free survival (PFS) of 26 months, when initially analyzed after a median follow-up of 30.6 months. The aim of this long-term follow-up was to investigate whether clinical benefits were maintained and new safety signals appeared. Fifty-nine patients, aged ≄ 50 years, with FL grade 1 to 3A in stages II to IV were treated with 90Y-IT as first-line therapy. If CR without evidence of minimal residual disease (MRD), partial response or stable disease was achieved 6 months after treatment, patients were observed without further treatment. Patients with CR but persisting MRD received consolidation therapy with rituximab. The primary endpoint was the clinical response rate. Secondary endpoints were time to progression, safety, and tolerability. After a median follow-up of 9.6 years, median PFS was 3.6 years, and 8-year PFS was 38.3%. Median overall survival (OS) was not reached during the extended follow-up, and 8-year OS amounted to 69.2%. Age 65 years and above or disease progression within 24 months of treatment were significantly associated with shorter OS. An important finding was the lack of new safety signals. In particular, no increase in secondary malignancies or transformation into aggressive lymphoma was observed compared to trials with a similar follow-up. In summary, 90Y-IT as first-line treatment demonstrates a favorable safety profile and long-term clinical activity in a substantial fraction of FL patients in need of therapy

    Search for composite and exotic fermions at LEP 2

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    A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio
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