3,448 research outputs found
Luigi Santarella: Reinforced concrete design culture through the technical literature
Luigi Santarella is considered to have been one of the most important Italian theorists in the field of reinforced concrete yet his professional activity is still completely ignored by the critical literature. The structures designed by Santarella – concrete frames, bridges, canopies for stadiums and roofing systems with innovative trusses – and built by contractors specializing in reinforced concrete construction represent the pragmatic experimental field of application of the building principles set out in his widespread theoretical books. The relationship between the building principles and the structural solutions analysed in his texts with his designed and realized structures, in the wider context of the design and construction culture of the time, will shed light on the interaction between the design process and construction instances as well as on the mechanics related to their dissemination through the technical literature
Mathematical Model of Easter Island Society Collapse
In this paper we consider a mathematical model for the evolution and collapse
of the Easter Island society, starting from the fifth century until the last
period of the society collapse (fifteen century). Based on historical reports,
the available primary sources consisted almost exclusively on the trees. We
describe the inhabitants and the resources as an isolated system and both
considered as dynamic variables. A mathematical analysis about why the
structure of the Easter Island community collapse is performed. In particular,
we analyze the critical values of the fundamental parameters driving the
interaction humans-environment and consequently leading to the collapse. The
technological parameter, quantifying the exploitation of the resources, is
calculated and applied to the case of other extinguished civilization (Cop\'an
Maya) confirming, with a sufficiently precise estimation, the consistency of
the adopted model.Comment: 9 pages, 1 figure, final version published on EuroPhysics Letter
Beyond the Death of Linear Response: 1/f optimal information transport
Non-ergodic renewal processes have recently been shown by several authors to
be insensitive to periodic perturbations, thereby apparently sanctioning the
death of linear response, a building block of nonequilibrium statistical
physics. We show that it is possible to go beyond the ``death of linear
response" and establish a permanent correlation between an external stimulus
and the response of a complex network generating non-ergodic renewal processes,
by taking as stimulus a similar non-ergodic process. The ideal condition of
1/f-noise corresponds to a singularity that is expected to be relevant in
several experimental conditions.Comment: 4 pages, 2 figures, 1 table, in press on Phys. Rev. Let
Primary cosmic ray spectrum in the 10 to the 12th power - 10 to the 16th power eV energy range from the NUSEX experiment
A primary cosmic ray spectrum was derived which fits both experimental multiple muon rates and the all-nucleon flux derived from the single muon intensities underground. In the frame of the interaction model developed by Gaisser, Elbert and Stanev, it is possible to reproduce NUSEX muon data with a primary composition in which the iron spectrum is only slightly flatter than the proton one. This result rules out the popular idea that the primary composition varies drastically with increasing energy, leading to the dominance of heavier nuclei at energies 10 to the 15th power to 10 to the 16th power eV
Results of low energy background measurements with the Liquid Scintillation Detector (LSD) of the Mont Blanc Laboratory
The 90 tons liquid scintillation detector (LSD) is fully running since October 1984, at a depth of 5,200 hg/sq cm of standard rock underground. The main goal is to search for neutrino bursts from collapsing stars. The experiment is very sensitive to detect low energy particles and has a very good signature to gamma-rays from (n,p) reaction which follows the upsilon e + p yields n + e sup + neutrino capture. The analysis of data is presented and the preliminary results on low energy measurements are discussed
Immunohistochemical expression of podoplanin (D2-40), lymphangiogenesis, and neoangiogenesis in tooth germ, ameloblastomas, and ameloblastic carcinomas
BACKGROUND: Ameloblastoma is a benign but locally aggressive odontogenic tumor, while ameloblastic carcinoma is its malignant counterpart. Angiogenesis and lymphangiogenesis in malignancies have been correlated with higher aggressiveness and poor prognosis, as well as greater expression of podoplanin by tumoral cells. METHODS: Immunohistochemical expression of podoplanin, CD34, and CD105 (endoglin) was evaluated in 53 ameloblastomas and three ameloblastic carcinomas; additionally, immunohistochemistry for podoplanin was also performed in 10 tooth germs. Microvessel density of blood and lymphatic vessels was calculated and compared between ameloblastomas and ameloblastic carcinomas. Immunoexpression of podoplanin by ameloblastic cells was evaluated in tooth germs, ameloblastomas, and ameloblastic carcinomas. RESULTS: Podoplanin was similarly expressed by odontogenic epithelial cells of tooth germs and ameloblastomas, while its expression was lower in ameloblastic carcinomas. There was no difference in microvessel density assessed by CD34 between ameloblastomas and ameloblastic carcinomas; nevertheless, the latter presented higher amounts of lymphatic and new formed blood vessels. CONCLUSIONS: Results suggest that podoplanin does not seem to be involved in invasion mechanisms of ameloblastic carcinomas, as its expression was decreased in the malignant tumoral cells. On the other hand, the increased lymphatic microvessel density and neoangiogenesis found in ameloblastic carcinomas could be related to its aggressiveness and potential for metastasis
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