Proton Spectrum at the Jupiter Laser Facility of LLNL

This paper looks at tungsten samples irradiated by beams of protons, gammas, electrons and positrons at the Jupiter Laser Facility of Lawrence Livermore National Laboratory (LLNL). The resulting unstable nuclei created are identified using their gamma spectra. These spectra were taken, usually within an hour of irradiation, for periods up to 48 hrs. In several cases there are two isotopes, one of Rhenium and the other of Tantalum, that emit the same gamma lines. These pairs often involve a long-lived and a short-lived candidate. Spectra were taken 80 days after initial exposure and the long-lived candidates are ruled out

Non-repudiation secure file transfer protocol (NRSFTP)

Non Repudiation Secure File Transfer Protocol (NRSFTP) is designed to resolve three main concerns for today\u27s electronic file transfer methodology. The three main concerns are Non-Repudiation, Secure, and Non-Real Time file transfer. Non-repudiation is to assure the receiver that the sender of the document is not an imposter. Secure document transfer is to assure the sender that only the intended receiver will be able to read the document. Non-real-time file transfer is to provide convenient and low cost transportability of the encrypted data from one party to another. With the above three concerns addressed, the NRSFTP protocol can be widely accepted by the general public as the method to securely transfer a file

Analysis of discrete dynamical system models for competing species

A discrete version of the Lotka-Volterra (LV) differential equations for competing population species is analyzed in detail, much the same way as the discrete form of the logistic equation has been investigated as a source of bifurcation phenomena and chaotic dynamics. Another related system, namely, the Exponentially Self Regulating (ESR) population model, is also thoroughly analyzed. It is found that in addition to logistic dynamics - ranging from the very simple to manifestly chaotic regimes in terms of the governing parameters - the discrete LV model and the ESR model exhibit their own brands of bifurcation and chaos that are essentially two dimensional in nature. In particular, it is shown that both systems exhibit twisted horseshoe dynamics associated to a strange invariant set for certain parameter ranges

Antenatal Depressive Symptoms and Antidepressant Use in Pregnancy

Review of the current literature reveals inconsistent findings on potential associations between antidepressant use during pregnancy and adverse fetal and child health and development. This study aims to examine the effect of antenatal SSRI exposure on several neonatal (preterm birth, small- and large-for-gestational age, Apgar score, and neonatal intensive care unit admission) and child developmental outcomes (measured by Ages and Stages Questionnaire) while controlling for confounding by indication. Data were obtained from the Prenatal Health Project, a longitudinal cohort study of 2,357 women in London, Ontario. Results from univariable analysis discovered that infants exposed to in utero SSRIs were more likely to be large-for-gestational age compared to infants of women exposed to antenatal depressive symptoms but not SSRIs and to infants of women unexposed to either antenatal depression or SSRIs. The small sample size of the antidepressant-exposed population limited our study and further research is warranted to verify the significance of our findings

Survival Probability in Dissociative Attachment

The survival probability in dissociative attachment is investigated with special attention to the (e, H2 ) system. It is shown that the simple expression for the dissociative-attachment cross section, as given by the product of a capture cross section and a survival probability, is equivalent to the s -wave approximation for the g → g dissociative attachment. This expression, however, does not constitute an approximation for the g → u dissociative attachment, since the parity of the initial rotational states of H2 is always opposite to that of the relative angular momentum states of H and H- and the capture cross section appearing in the simple expression is identically zero. According to the Kronig selection rules and the symmetry requirements, only odd partial waves of the incident electron may contribute to the g → u dissociative attachment in the (e, H2 ) system. Consequently, the lowest contributing partial wave is not the s wave but the p wave of the incident electron. This, then, destroys the simple proportional dependence of the cross section on the survival probability. However, one may still express the cross section as a sum of products of a capture cross section and a survival probability for the various contributing angular momentum states of the constituent nuclei. The dependence of the survival probability on the angular momentum states of the constituent nuclei is also investigated for the (e, H2) system. It is observed that for the g → u dissociative attachment the survival probability depends strongly on the angular momentum states. This arises because the g → u dissociative attachment occurs at such a low energy that variations in the centrifugal barrier become comparable with the breakup energy of the constituent atoms. This then suggests a strong temperature dependence for the g → u dissociative attachment in the (e, H2) system. For the g → g dissociative attachment, such dependence is much weaker since here the process significant at a somewhat higher energy and the variation in centrifugal energy is overshadowed by the larger break-up energy of the constituent atoms. The validity of the commonly adopted approximation for survival probability (involving the auto-ionization width and relative velocity of the nuclei) is also examined

Interaction Potential between the Ground States of H and Hˉ

An investigation of the interaction potential for H and H- in both ungerade and gerade modes is carried out by a semiempirical method in which the recently observed isotope effect in dissociative attachment of electrons to hydrogen molecules is used. The interaction obtained is complex, and the imaginary parts of the interaction account for electron emissions during the course of the interaction. A comparison of the present result with other calculations is presented. The isotope effect in dissociative attachment is also discussed. It is shown that the ratios of the survival probabilities alone do not provide an adequate approximation for the isotope effect