263 research outputs found
Effect of multiple reusing of simulated air showers in detector simulations
The study of high energy cosmic rays requires detailed Monte Carlo
simulations of both, extensive air showers and the detectors involved in their
detection. In particular, the energy calibration of several experiments is
obtained from simulations. Also, in composition studies simulations play a
fundamental role because the primary mass is determined by comparing
experimental with simulated data. At the highest energies the detailed
simulation of air showers is very costly in processing time and disk space due
to the large number of secondary particles generated in interactions with the
atmosphere. Therefore, in order to increase the statistics, it is quite common
to recycle single showers many times to simulate the detector response. As a
result, the events of the Monte Carlo samples generated in this way are not
fully independent. In this work we study the artificial effects introduced by
the multiple use of single air showers for the detector simulations. In
particular, we study in detail the effects introduced by the repetitions in the
kernel density estimators which are frequently used in composition studies.Comment: 15 pages and 4 figure
Morphological Properties of Superclusters of Galaxies
We studied superclusters of galaxies in a volume-limited sample extracted
from the Sloan Digital Sky Survey Data Release 7 (SDSS/DR7) and from mock
catalogues based on a semi-analytical model of galaxy evolution in the
Millenium Simulation. A density field method was applied to a sample of
galaxies brighter than to identify superclusters,
taking into account selection and boundary effects. In order to evaluate the
influence of threshold density, we have chosen two thresholds: the first
maximizes the number of objects (D1), and the second constrains the maximum
supercluster size to 120~hMpc (D2). We have performed a
morphological analysis, using Minkowski Functionals, based on a parameter which
increases monotonically from filaments to pancakes. An anti-correlation was
found between supercluster richness (and total luminosity or size) and the
morphological parameter, indicating that filamentary structures tend to be
richer, larger and more luminous than pancakes in both observed and mock
catalogues. We have also used the mock samples to compare supercluster
morphologies identified in position and velocity spaces, concluding that our
morphological classification is not biased by the peculiar velocities. Monte
Carlo simulations designed to investigate the reliability of our results with
respect to random fluctuations show that these results are robust. Our analysis
indicates that filaments and pancakes present different luminosity and size
distributions.Comment: 12 pages, 17 figures Accepted to MNRA
Inverse planned stereotactic intensity modulated radiotherapy (IMRT) in the treatment of incompletely and completely resected adenoid cystic carcinomas of the head and neck: initial clinical results and toxicity of treatment
BACKGROUND: Presenting the initial clinical results in the treatment of complex shaped adenoid cystic carcinomas (ACC) of the head and neck region by inverse planned stereotactic IMRT. MATERIALS: 25 patients with huge ACC in different areas of the head and neck were treated. At the time of radiotherapy two patients already suffered from distant metastases. A complete resection of the tumor was possible in only 4 patients. The remaining patients were incompletely resected (R2: 20; R1: 1). 21 patients received an integrated boost IMRT (IBRT), which allow the use of different single doses for different target volumes in one fraction. All patients were treated after inverse treatment planning and stereotactic target point localization. RESULTS: The mean folllow-up was 22.8 months (91 – 1490 days). According to Kaplan Meier the three year overall survival rate was 72%. 4 patients died caused by a systemic progression of the disease. The three-year recurrence free survival was according to Kaplan Meier in this group of patients 38%. 3 patients developed an in-field recurrence and 3 patient showed a metastasis in an adjacent lymph node of the head and neck region. One patient with an in-field recurrence and a patient with the lymph node recurrence could be re-treated by radiotherapy. Both patients are now controlled. Acute side effects >Grade II did only appear so far in a small number of patients. CONCLUSION: The inverse planned stereotactic IMRT is feasible in the treatment of ACC. By using IMRT, high control rates and low side effects could by achieved. Further evaluation concerning the long term follow-up is needed. Due to the technical advantage of IMRT this treatment modality should be used if a particle therapy is not available
Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice
Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales
Elevating Mallarmé’s Shipwreck
This paper discusses collage as a means to explore spatial ideas. It concerns the practice of drawing-as-research, the spatiality of drawing and the nature of paper. It questions the homogeneity of digital tools in contemporary practice. It is introduced with a discussion of architectural representation and space with a historical trajectory. It questions an understanding of space-as-geometry and discusses the potential role of non-perspectival drawings and non-digital drawing in current practice. The collage studies focus on the late nineteenth century. Working in the tradition of the collage novel, and with original engravings from the popular French newspaper Le Grande Illustré (1904), the collages work with the thematic structure and spatiality of Stéphane Mallarmé’s revolutionary poem Un Coup de Dés written a few years earlier. In this paper, the spatial and thematic content of Mallarmé’s poem are visualized for the first time. The conclusions of this study concern the role of non-digital drawings in the profession, and the potential of creative “paper technologies” to engage the material imagination at the early stages of a design process. It opens new ground as a study of the spatiality of text, the relationship between dramaturgy and architecture and on the nature of topological drawings
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