Entrance-channel Mass-asymmetry Dependence of Compound-nucleus Formation Time in Light Heavy-ion Reactions

The entrance-channel mass-asymmetry dependence of the compound nucleus formation time in light heavy-ion reactions has been investigated within the framework of semiclassical dissipative collision models. the model calculations have been succesfully applied to the formation of the $^{38}$Ar compound nucleus as populated via the $^{9}$Be+$^{29}$Si, $^{11}$B+$^{27}$Al, $^{12}$C+$^{26}$Mg and $^{19}$F+$^{19}$F entrance channels. The shape evolution of several other light composite systems appears to be consistent with the so-called "Fusion Inhibition Factor" which has been experimentally observed. As found previously in more massive systems for the fusion-evaporation process, the entrance-channel mass-asymmetry degree of freedom appears to determine the competition between the different mechanisms as well as the time scales involved.Comment: 12 pages, 3 Figures available upon request, Submitted at Phys. Rev.

Resonant and nonresonant D+ -> K- pi+ l+ nu(l) semileptonic decays

We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective Lagrangian developed previously to describe the decays D -> P l nu(l) and D -> V l nu(l). Light vector mesons are included in the model which combines the heavy quark effective Lagrangian and chiral perturbation theory approach. The nonresonant and resonant contributions are compared. With no new parameters the model correctly reproduces the measured ratio Gamma(nres)/Gamma(nres + res). We also present useful nonresonant decay distributions. Finally, a similar model, but with a modified current which satisfies the soft pion theorems at the expense of introducing another parameter, is analyzed and the results of the models are compared.Comment: 17 pages, 3 Postscript figures, standard Latex, extended revision, title, abstract and text (especially Sec. IV) changed, results unchange

carapa guianensis aubl. and Carapa procera DC. (meliaceae)] by insects in Amazon

The objectives of this study were to identify the insects associated to seed predation of Carapa guianensis and Carapa procera, to evaluate the seeds damage potential of these insects and the occurrence of vertical stratification in the predation of Carapa seeds. The study was carried out in C. guianensis and C. procera plantations at Reserva Florestal Ducke, Manaus, Amazonas State, Brazil. The seed samples from the ground were taken weekly, and the canopy samples were taken monthly from three different heights. To evaluate the effect of predation on germination, 30 non-predated seeds and 30 predated seeds were collected monthly from the ground at each plot, and the germination was monitored during a month. The results showed that Hypsipyla grandella and H. ferrealis (Lepidoptera: Pyralidae) are the main insect species associated to seed predation in C. procera and C. guianensis, with predation mean rates of 39% to 61,96%, respectively. Fruit and seed predation were observed inside the canopy vertical stratification of the two Carapa species. The seed predation in C. procera and C. guianensis by Hypsipyla spp. reduced the germination process. This study produced information on the association between C. procera and C. guianensis and the species of Hypsipyla

Comparação entre a pressão inspiratória máxima aferida pelo manovacuômetro digital e pelo dispositivo eletrônico de treinamento muscular inspiratório

Aims: To compare maximum inspiratory pressure (MIP) measured by a digital manometer and by an inspiratory muscle training (IMT) device and to evaluate hemodynamic changes after measurements. Methods: The sample included male and female individuals older than 18 years admitted to an intensive care unit who were hemodynamically stable, not being treated with vasoactive drugs or sedated, intubated or tracheostomized, and who were in the process of being weaned from mechanical ventilation. MIP was measured by both devices on three different occasions, with an occlusion time of 20 seconds and a 5-minute interval between measurements. The following parameters were assessed: respiratory rate, mean arterial pressure, and respiratory rate before and after each measurement by each device. The statistical analysis was made in the Statistical Analysis System and the R Project for Statistical Computing V. 3.1.2 softwares, using the ANOVA and the Wilcoxon tests. Results: Fifty-eight patients were included in the study. The mean value obtained for MIP was -46.22 centimeters of water (cmH2O) in the digital manometer and -13.15 cmH2O (p<0.001) in the IMT device. Heart rate showed a significant increase (p<0.0001) both before and after all measurements in both devices. Mean arterial pressure showed a statistically significant difference only before and after the first measurement by the digital manometer and before and after the second measurement by the IMT device (p<0.001). The respiratory rate oscillated significantly before and after the three measurements by both devices (p<0.0001). The hemodynamic parameters remained within reference values after MIP measurements. Conclusions: The digital manometer recorded a higher MIP than that measured by the IMT device. The hemodynamic parameter values oscillated in both devices, but they remained within the normal range and were not clinically significant.To compare maximum inspiratory pressure (MIP) measured by a digital manometer and by an inspiratory muscle training (IMT) device and to evaluate hemodynamic changes after measurements. Methods: The sample included male and female individuals older than 182616Comparar valores de pressão inspiratória máxima (PImáx) aferidos por um manovacuômetro digital e por um dispositivo eletrônico de treinamento muscular inspiratório e avaliar as repercussões hemodinâmicas após as medidas. MÉTODOS: A amostra foi composta p

Sample size estimation for randomised controlled trials with repeated assessment of patient-reported outcomes : what correlation between baseline and follow-up outcomes should we assume?

Background Patient-reported outcome measures (PROMs) are now frequently used in randomised controlled trials (RCTs) as primary endpoints. RCTs are longitudinal, and many have a baseline (PRE) assessment of the outcome and one or more post-randomisation assessments of outcome (POST). With such pre-test post-test RCT designs there are several ways of estimating the sample size and analysing the outcome data: analysis of post-randomisation treatment means (POST); analysis of mean changes from pre- to post-randomisation (CHANGE); analysis of covariance (ANCOVA). Sample size estimation using the CHANGE and ANCOVA methods requires specification of the correlation between the baseline and follow-up measurements. Other parameters in the sample size estimation method being unchanged, an assumed correlation of 0.70 (between baseline and follow-up outcomes) means that we can halve the required sample size at the study design stage if we used an ANCOVA method compared to a comparison of POST treatment means method. So what correlation (between baseline and follow-up outcomes) should be assumed and used in the sample size calculation? The aim of this paper is to estimate the correlations between baseline and follow-up PROMs in RCTs. Methods The Pearson correlation coefficients between the baseline and repeated PROM assessments from 20 RCTs (with 7173 participants at baseline) were calculated and summarised. Results The 20 reviewed RCTs had sample sizes, at baseline, ranging from 49 to 2659 participants. The time points for the post-randomisation follow-up assessments ranged from 7 days to 24 months; 464 correlations, between baseline and follow-up, were estimated; the mean correlation was 0.50 (median 0.51; standard deviation 0.15; range − 0.13 to 0.91). Conclusions There is a general consistency in the correlations between the repeated PROMs, with the majority being in the range of 0.4 to –0.6. The implications are that we can reduce the sample size in an RCT by 25% if we use an ANCOVA model, with a correlation of 0.50, for the design and analysis. There is a decline in correlation amongst more distant pairs of time points

No evidence of break-up effects on the fusion of 9Be with medium-light nuclei

AbstractFusion cross sections were measured for the 9Be+27Al and 19F+9Be, 12C systems, at energies above the Coulomb barrier, in order to investigate the possible effect of fusion hindrance due to the break-up of the weakly bound nuclei. Comparisons with one-dimensional barrier penetration models and with other similar systems, where no break-up is expected to occur, show no evidence of fusion hindrance

Leptonic and Semileptonic Decays of Charm and Bottom Hadrons

We review the experimental measurements and theoretical descriptions of leptonic and semileptonic decays of particles containing a single heavy quark, either charm or bottom. Measurements of bottom semileptonic decays are used to determine the magnitudes of two fundamental parameters of the standard model, the Cabibbo-Kobayashi-Maskawa matrix elements $V_{cb}$ and $V_{ub}$. These parameters are connected with the physics of quark flavor and mass, and they have important implications for the breakdown of CP symmetry. To extract precise values of $|V_{cb}|$ and $|V_{ub}|$ from measurements, however, requires a good understanding of the decay dynamics. Measurements of both charm and bottom decay distributions provide information on the interactions governing these processes. The underlying weak transition in each case is relatively simple, but the strong interactions that bind the quarks into hadrons introduce complications. We also discuss new theoretical approaches, especially heavy-quark effective theory and lattice QCD, which are providing insights and predictions now being tested by experiment. An international effort at many laboratories will rapidly advance knowledge of this physics during the next decade.Comment: This review article will be published in Reviews of Modern Physics in the fall, 1995. This file contains only the abstract and the table of contents. The full 168-page document including 47 figures is available at http://charm.physics.ucsb.edu/papers/slrevtex.p

Determination of the Strange Quark Content of the Nucleon from a Next-to-Leading-Order QCD Analysis of Neutrino Charm Production

We present the first next-to-leading-order QCD analysis of neutrino charm production, using a sample of 6090 $\nu_\mu$- and $\bar\nu_\mu$-induced opposite-sign dimuon events observed in the CCFR detector at the Fermilab Tevatron. We find that the nucleon strange quark content is suppressed with respect to the non-strange sea quarks by a factor \kappa = 0.477 \: ^{+\:0.063}_{-\:0.053}, where the error includes statistical, systematic and QCD scale uncertainties. In contrast to previous leading order analyses, we find that the strange sea $x$-dependence is similar to that of the non-strange sea, and that the measured charm quark mass, $m_c = 1.70 \pm 0.19 \:{\rm GeV/c}^2$, is larger and consistent with that determined in other processes. Further analysis finds that the difference in $x$-distributions between $xs(x)$ and $x\bar s(x)$ is small. A measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|=0.232 ^{+\:0.018}_{-\:0.020}$ is also presented. uufile containing compressed postscript files of five Figures is appended at the end of the LaTeX source.Comment: Nevis R#150

Strong Decays of Strange Quarkonia

In this paper we evaluate strong decay amplitudes and partial widths of strange mesons (strangeonia and kaonia) in the 3P0 decay model. We give numerical results for all energetically allowed open-flavor two-body decay modes of all nsbar and ssbar strange mesons in the 1S, 2S, 3S, 1P, 2P, 1D and 1F multiplets, comprising strong decays of a total of 43 resonances into 525 two-body modes, with 891 numerically evaluated amplitudes. This set of resonances includes all strange qqbar states with allowed strong decays expected in the quark model up to ca. 2.2 GeV. We use standard nonrelativistic quark model SHO wavefunctions to evaluate these amplitudes, and quote numerical results for all amplitudes present in each decay mode. We also discuss the status of the associated experimental candidates, and note which states and decay modes would be especially interesting for future experimental study at hadronic, e+e- and photoproduction facilities. These results should also be useful in distinguishing conventional quark model mesons from exotica such as glueballs and hybrids through their strong decays.Comment: 69 pages, 5 figures, 39 table