641 research outputs found

    Emerging Role of Hypofractionated Radiotherapy with Simultaneous Integrated Boost in Modern Radiotherapy of Breast Cancer

    Get PDF
    Hypofractionated radiotherapy for breast cancer is becoming increasingly important. The scientific background of this development as well as the introduction of the simultaneous integrated boost to the primary tumor region in this context are discussed here

    Modelling and Simulation of Asynchronous Real-Time Systems using Timed Rebeca

    Full text link
    In this paper we propose an extension of the Rebeca language that can be used to model distributed and asynchronous systems with timing constraints. We provide the formal semantics of the language using Structural Operational Semantics, and show its expressiveness by means of examples. We developed a tool for automated translation from timed Rebeca to the Erlang language, which provides a first implementation of timed Rebeca. We can use the tool to set the parameters of timed Rebeca models, which represent the environment and component variables, and use McErlang to run multiple simulations for different settings. Timed Rebeca restricts the modeller to a pure asynchronous actor-based paradigm, where the structure of the model represents the service oriented architecture, while the computational model matches the network infrastructure. Simulation is shown to be an effective analysis support, specially where model checking faces almost immediate state explosion in an asynchronous setting.Comment: In Proceedings FOCLASA 2011, arXiv:1107.584

    Influence of volcanic eruptions on midlatitude upper tropospheric aerosol and consequences for cirrus clouds – Volc Affects S Aerosol in UT and Cirrus

    Get PDF
    The influence of downwelling stratospheric sulfurous aerosol on the UT (upper troposphere) aerosol concentrations and on cirrus clouds is investigated using CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container observations) (between 1999–2002 and 2005–2013) and the cirrus reflectance product from Moderate Resolution Imaging Spectroradiometer (MODIS). The initial period, 1999–2002, was volcanically quiescent after which the sulfurous aerosol in the LMS (lowermost stratosphere) (SLMS_{LMS}) became enhanced by several volcanic eruptions starting 2005. From 2005 to 2008 and in 2013, volcanic aerosol from several tropical eruptions increased SLMS_{LMS}. Due to consequent subsidence, the sulfur loading of the upper troposphere (SUT_{UT}) was increased by a factor of 2.5 compared to background levels. Comparison of SLMS and SUT_{UT} during the seasons March–July and August–November shows a close coupling of the UT and LMS. Finally, the relationship between SLMS_{LMS} and the cirrus cloud reflectance (CR) retrieved from MODIS spectrometer (on board the satellites Terra and Aqua) is studied. SLMS_{LMS} and CR show a strong anticorrelation, with a factor of 3.5 increase in SLMS and decrease of CR by 8 ± 2% over the period 2001–2011. We propose that the increase of SLMS_{LMS} due to volcanism has caused the coinciding cirrus CR decrease, which would be associated with a negative radiative forcing in the Northern Hemisphere midlatitudes

    An optical particle size spectrometer for aircraft-borne measurements in IAGOS-CARIBIC

    Get PDF
    The particle number size distribution is an important parameter to characterize the atmospheric aerosol and its influence on the Earth's climate. Here we describe a new optical particle size spectrometer (OPSS) for measurements of the accumulation mode particle number size distribution in the tropopause region on board a passenger aircraft (IAGOS-CARIBIC observatory: In-service Aircraft for a Global Observing System - Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container). A modified KS93 particle sensor from RION Co., Ltd., together with a new airflow system and a dedicated data acquisition system, is the key component of the CARIBIC OPSS. The instrument records individual particle pulse signal curves in the particle size range 130-1110 nm diameter (for a particle refractive index of 1.47-i0.006) together with a time stamp and thus allows the post-flight choice of the time resolution and the size distribution bin width. The CARIBIC OPSS has a 50 % particle detection diameter of 152 nm and a maximum asymptotic counting efficiency of 98 %. The instrument's measurement performance shows no pressure dependency and no particle coincidence for free tropospheric conditions. The size response function of the CARIBIC OPSS was obtained by a polystyrene latex calibration in combination with model calculations. Particle number size distributions measured with the new OPSS in the lowermost stratosphere agreed within a factor of 2 in concentration with balloon-borne measurements over western North America. Since June 2010 the CARIBIC OPSS is deployed once per month in the IAGOS-CARIBIC observatory

    Sources of increase in lowermost stratospheric sulphurous and carbonaceous aerosol background concentrations during 1999–2008 derived from CARIBIC flights

    Get PDF
    This study focuses on sulphurous and carbonaceous aerosol, the major constituents of particulate matter in the lowermost stratosphere (LMS), based on in situ measurements from 1999 to 2008. Aerosol particles in the size range of 0.08-2 μm were collected monthly during intercontinental flights with the CARIBIC passenger aircraft, presenting the first long-term study on carbonaceous aerosol in the LMS. Elemental concentrations were derived via subsequent laboratory-based ion beam analysis. The stoichiometry indicates that the sulphurous fraction is sulphate, while an O/C ratio of 0.2 indicates that the carbonaceous aerosol is organic. The concentration of the carbonaceous component corresponded on average to approximately 25% of that of the sulphurous, and could not be explained by forest fires or biomass burning, since the average mass ratio of Fe to K was 16 times higher than typical ratios in effluents from biomass burning. The data reveal increasing concentrations of particulate sulphur and carbon with a doubling of particulate sulphur from 1999 to 2008 in the northern hemisphere LMS. Periods of elevated concentrations of particulate sulphur in the LMS are linked to downward transport of aerosol from higher altitudes, using ozone as a tracer for stratospheric air. Tropical volcanic eruptions penetrating the tropical tropopause are identified as the likely cause of the particulate sulphur and carbon increase in the LMS, where entrainment of lower tropospheric air into volcanic jets and plumes could be the cause of the carbon increase

    The unexpected resurgence of Weyl geometry in late 20-th century physics

    Full text link
    Weyl's original scale geometry of 1918 ("purely infinitesimal geometry") was withdrawn by its author from physical theorizing in the early 1920s. It had a comeback in the last third of the 20th century in different contexts: scalar tensor theories of gravity, foundations of gravity, foundations of quantum mechanics, elementary particle physics, and cosmology. It seems that Weyl geometry continues to offer an open research potential for the foundations of physics even after the turn to the new millennium.Comment: Completely rewritten conference paper 'Beyond Einstein', Mainz Sep 2008. Preprint ELHC (Epistemology of the LHC) 2017-02, 92 pages, 1 figur

    Uma coleção de história em um museu de ciências naturais: o Museu Paulista de Hermann von Ihering

    Get PDF
    Instalado em um edifício-Monumento, data de 1895 a inauguração do Museu Paulista. Seu primeiro diretor, o zoólogo Hermann Von Ihering (1895-1916), teve a tarefa de organizar suas vastas coleções, as quais possuíam objetos de diversos ramos do conhecimento, entre eles, a História. Este artigo tem a intenção de entender a dimensão, dinâmica e concepção desta coleção de História, que recebeu pouca atenção da Historiografia relativa ao tema.The Museu Paulista, installed in a landmark building, was inaugurated in 1895. Its first director, the zoologist Herman von Ihering (1895-1916) undertook the assignment of organizing its extensive collections, which comprehended objects pertaining to varied fields of knowledge, including that of History. The present article aims at understanding the dimension, the dynamics and the conception of this historical collection. Until now little attention has been bestowed upon this subject matter by the specialized historiography

    Submicron Structures Fabrication and Research

    Get PDF
    Contains reports on thirteen research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0908)National Science Foundation (Grant ECS82-05701)I.B.M. (PO No. 90305-QPSA-559)U.S. Department of Energy (Contract DE-AC02-82-ER13019)Lawrence Livermore Laboratory (Contract 2069209
    corecore