48 research outputs found

    Morphological studies in modern teratological investigations

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    Despite the variety of modern molecular techniques available, examination of foetal anatomy is still a fundamental part of teratological studies in evaluating the developmental toxicity of xenobiotics or other non-chemical factors. The article presents contemporary methods of embryotoxicity and foetotoxicity assessment. A single alizarin red S and double alcian blue followed by alizarin red S staining, as well as various methods of soft tissue examination are discussed

    Faddeev Calculations of Proton-Deuteron Radiative Capture with Exchange Currents

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    pd capture processes at various energies have been analyzed based on solutions of 3N-Faddeev equations and using modern NN forces. The application of the Siegert theorem is compared to the explicit use of π\pi- and ρ\rho-like exchange currents connected to the AV18 NN interaction. Overall good agreement with cross sections and spin observables has been obtained but leaving room for improvement in some cases. Feasibility studies for 3NF's consistently included in the 3N continuum and the 3N bound state have been performed as well.Comment: Minor changes in notation, ps files for figure

    Photonuclear Reactions of Three-Nucleon Systems

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    We discuss the available data for the differential and the total cross section for the photodisintegration of 3^3He and 3^3H and the corresponding inverse reactions below Eγ=100E_\gamma = 100 MeV by comparing with our calculations using realistic NNNN interactions. The theoretical results agree within the errorbars with the data for the total cross sections. Excellent agreement is achieved for the angular distribution in case of 3^3He, whereas for 3^3H a discrepancy between theory and experiment is found.Comment: 11 pages (twocolumn), 12 postscript figures included, uses psfig, RevTe

    Electron and Photon Scattering on Three-Nucleon Bound States

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    A big spectrum of processes induced by real and virtual photons on the 3He and 3H nuclei is theoretically investigated through many examples based on nonrelativistic Faddeev calculations for bound and continuum states. The modern nucleon-nucleon potential AV18 together with the three-nucleon force UrbanaIX is used. The single nucleon current is augmented by explicit pi- and rho-like two-body currents which fulfill the current continuity equation together with the corresponding parts of the AV18 potential. We also employ the Siegert theorem, which induces many-body contributions to the current operator. The interplay of these different dynamical ingredients in the various electromagnetic processes is studied and the theory is compared to the experimental data. Overall we find fair to good agreement but also cases of strong disagreement between theory and experiment, which calls for improved dynamics. In several cases we refer the reader to the work of other groups and compare their results with ours. In addition we list a number of predictions for observables in different processes which would challenge this dynamical scenario even more stringently and systematically.Comment: 154 pages, 80 figures includes as ps files, 21 additional figures as jpeg file

    The Comet Interceptor Mission

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    Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

    Virtual Advising: A Foundation for Success

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    This session will focus on creating an effective virtual advising center for online programs; while most applicable to higher education, all attendees who use online training/orientation could not only benefit from the session, but also contribute useful insights. The session will demonstrate the effectiveness of orientation as related to students’ suitability for online learning (pre-enrollment) and retention (post-enrollment); identify methods of using tools in the LMS to engage the student with the program, their cohort, and the LMS itself; describe content that is vital to immediate/early orientation, and explain what of that content must carry through ongoing advising; list essential elements to consider when building a virtual advising center; and explore best practices from other institutions/organizations through open discussion. My programs at UF show greater success and retention rates from students who complete pre-enrollment orientation, which connects the students to each other to immediately break down the potential isolation distance learners may feel, provides an interactive platform through which to learn about key university and program policies, and remains a site that students can access for “just in time” information throughout their degree. Whereas residential students can drop into various campus offices for service, distance students are often left to navigate myriad websites searching for answers. Our virtual advising center compiles all of these resources into one location, and explains best practices for effective communication with campus-based offices that are sometimes unaware of the distinct needs of distance learners. As the developer and manager of our virtual advising center, I will share my experiences of building these sites, and how ongoing maintenance and regular updating of information can be handled quickly. The initial time investment in creating these sites now makes them easy to update term-by-term, allowing time to answer more in-depth student questions and concerns while still providing them thorough service

    High performance computing at IBM: The Bluegene/L supercomputer

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