5,147 research outputs found
Erosione localizzata al piede di ostacoli in alveo: studio sperimentale su un dispositivo di controllo
No full textGenov
Clusters of firms in space and time
No full textThe use of the K-functions (Ripley, 1977) has become recently popular in the analysis of the spatial pattern of firms. It was first introduced in the economic literature by Arbia and Espa (1996) and then popularized by Marcon and Puech (2003), Quah and Simpson (2003), Duranton and Overman (2005) and Arbia et al. (2008). In particular in Arbia et al. (2008) we used Ripley’s K-functions as instruments to study the inter-sectoral co-agglomeration pattern of firms in a single moment of time. All this researches have followed a static approach, disregarding the time dimension. Temporal dynamics, on the other hand, play a crucial role in understanding the economic and social phenomena, particularly when referring to the analysis of the individual choices leading to the observed clusters of economic activities. With respect to the contributions previously appeared in the literature, this paper uncovers the process of firm demography by studying the dynamics of localization through space-time K-functions. The empirical part of the paper will focus on the study of the long run localization of firms in the area of Rome (Italy), by concentrating on the ICT sector data collected by the Italian Industrial Union in the period 1920- 2005.Agglomeration, Non-parametric measures; Space-time K-functions, Spatial clusters, Spatial econometrics.
Aspetti morfologici della cartilagine articolare umana in corso di artrosi.Osservazioni al microscopio elettronico a scansione.
No full textA Semi-Unsupervised Segmentation Methodology Based on Texture Recognition for Radiomics: A Preliminary Study on Brain Tumours
No full textBecause of the intrinsic anatomic complexity of the brain structures, brain tumors have a high mortality and disability rate, and an early diagnosis is mandatory to contain damages. The commonly used biopsy is the diagnostic gold standard method, but it is invasive and, due to intratumoral heterogeneity, biopsies may lead to an incorrect result. Moreover, some tumors cannot be resectable if located in critical eloquent areas. On the other hand, medical imaging procedures can evaluate the entire tumor in a non-invasive and reproducible way. Radiomics is an emerging diagnosis technique based on quantitative medical image analyses, which makes use of data provided by non-invasive diagnosis techniques such as X-ray, computer-tomography (CT), magnetic resonance (MR), and proton emission tomography (PET). Radiomics techniques require the comprehensive analysis of huge numbers of medical images to extract a large and useful number of phenotypic features (usually called radiomics biomarkers). The goal is to explore and obtain the associations between features of tumors, diagnosis and patients’ prognoses to choose the best treatments and maximize the patient’s survival rate. Current radiomics techniques are not standardized in term of segmentation, feature extraction, and selection, moreover, the decision on suitable therapies still requires the supervision of an expert doctor. In this paper, we propose a semi-automatic methodology aimed to help the identification and segmentation of malignant tissues by using the combination of binary texture recognition, growing area algorithm, and machine learning techniques. In particular, the proposed method not only helps to better identify pathologic tissues but also permits to analyze in a fast way the huge amount of data, in Dicom format, provided by non-invasive diagnostic techniques. A preliminary experimental assessment has been conducted, considering a real MRI database of brain tumors. The method has been compared with the segmentation software’s tools “slicer 3D”. The obtained results are quite promising and demonstrate the potentialities of the proposed semi-unsupervised segmentation methodology
Espa?os (semi)p?blicos de sociabilidade juvenil em Chapec?
No full textThe use of geographic space is the central point of observation of the daily
activities of human societies. One of these activities that play a fundamental role
in group living is sociability, which requires adequate space for its
accomplishment. In capitalist society, where private property is a guaranteed
right, public spaces become less and less important in relation to the private ones.
These, besides the space itself, offer other attractions usually linked to
consumption. A clear and recurrent example of private space that is used as if it
were public by society are the shopping malls. These are enterprises that
combine consumption, leisure and sociability, and they are very present in
metropolises and intermediate cities, as it is the case of Chapec?, a city located
in the western region of the state of Santa Catarina. In Chapec?, some kinds of
youth have difficulties in finding public spaces for practicing sociability, which
means that they often use private spaces for this purpose. This private space is
one of the objects of study of this research, the Havan?s parking, which during
the night time serves as a semi-public space for youth. The objective of this
research was to analyze the spaces occupied by young people and, through
empirical research, to observe why this private space has been chosen for the
practice of sociability, and which are the difficulties they face in occupying these
semi-public spaces. The spaces need to meet the needs of youthful sociability,
otherwise private spaces will be occupied, even if the public power uses
strategies that hinder these movements of sociability.O uso do espa?o geogr?fico ? ponto central de observa??o das atividades
cotidianas das sociedades humanas. Uma dessas atividades que t?m papel
fundamental na viv?ncia em grupo ? a sociabilidade, que exige um espa?o
adequado para sua realiza??o. Na sociedade capitalista, onde a propriedade
privada ? um direito garantido, os espa?os p?blicos se tornam cada vez menos
importantes diante dos privados. Estes, al?m do espa?o em si, disponibilizam
outros atrativos geralmente ligados ao consumo. Um exemplo claro e recorrente
de espa?o privado que ? utilizado como se fosse p?blico pela sociedade s?o os
shopping centers. Esses empreendimentos que aliam o consumo, o lazer e a
sociabilidade est?o muito presentes em metr?poles e cidades m?dias, como ? o
caso de Chapec?, cidade m?dia localizada na regi?o oeste do estado de Santa
Catarina. Em Chapec?, alguns tipos de jovens encontram dificuldades para
encontrar espa?os p?blicos para a pr?tica da sociabilidade, o que faz com que
muitas vezes utilizem espa?os privados para isso. Esse espa?o privado ? um
dos objetos de estudo dessa pesquisa, o estacionamento da Havan, que durante
o per?odo noturno serve como espa?o semip?blico para a juventude. O objetivo
dessa pesquisa foi analisar os espa?os ocupados pelos jovens e, atrav?s de
pesquisa emp?rica, observar porque esse espa?o privado tem sido escolhido
para a pr?tica da sociabilidade e quais as dificuldades que eles encontram ao
ocupar esses espa?os semip?blicos. Os espa?os precisam atender as
necessidades de sociabilidade juvenil, se isso n?o acontecer espa?os privados
ser?o ocupados, mesmo que o poder p?blico use estrat?gias que dificultem
esses movimentos de sociabilidade
Growth, convergence and public investment. A Bayesian model averaging approach
No full textThe aim of this study is twofold. First, the determinants of economic growth are studied among a wide set of potential variables for the Spanish provinces (NUTS3). Among others, various types of private, public and human capital in the group of growth factors are included. Also, it is analysed whether Spanish provinces have converged in economic terms in recent decades. The second objective is to obtain cross-section and panel data parameter estimates that are robust to model specification. For this purpose, a Bayesian Model Averaging (BMA) approach is used. Bayesian methodology constructs parameter estimates as a weighted average of linear regression estimates for every possible combination of included variables. The weight of each regression estimate is given by the posterior probability of each model.
Downstream ecological impacts of controlled sediment flushing in an alpine valley river: a case study
No full textSediment flushing may be effective to tackle the loss of reservoir storage as a result of siltation. When operationally possible, the impact of this practice on the downstream aquatic environment can be mitigated by limiting the sediment concentration of the discharged waters (controlled sediment flushing). However, this topic is poorly documented, and concerns arise when limits are discussed. We present the results of a 3-year field investigation concerning the controlled sediment flushing of a small reservoir on the Adda River, the main tributary of Lake Como-Italy. Two limits for suspended solid concentration (SSC) were adopted: 1.5gL-1, as average value throughout the whole working day, and 3.0gL-1, as alert threshold to adjust the ongoing activity. These constraints were essentially fulfilled in the course of the documented operations. The first year sediment flushing was more significant than the following year: 25000 tons of fines below 2mm in diameter were flushed in six non-consecutive days in summer 2010, while, one year earlier, 75000 tons were flushed in 16 non-consecutive days. In the third year of investigation (2011), no sediment evacuation took place. The benthic macroinvertebrate and the fish communities were surveyed a short distance below the reservoir, that is, in the potentially more affected river reach. Clear pieces of evidence of environmental quality degradation were not detected; the adopted strategies can therefore be considered to be appropriate when planning sediment flushing management in comparable contexts
Weighting Ripley’s K-function to account for the firm dimension in the analysis of spatial concentration
No full textThe spatial concentration of firms has long been a central issue in economics both under the theoretical and the applied point of view due mainly to the important policy implications. A popular approach to its measurement, which does not suffer from the problem of the arbitrariness of the regional boundaries, makes use of micro data and looks at the firms as if they were dimensionless points distributed in the economic space. However in practical circumstances the points (firms) observed in the economic space are far from being dimensionless and are conversely characterized by different dimension in terms of the number of employees, the product, the capital and so on. In the literature, the works that originally introduce such an approach (e.g. Arbia and Espa, 1996; Marcon and Puech, 2003) disregard the aspect of the different firm dimension and ignore the fact that a high degree of spatial concentration may result from both the case of many small points clustering in definite portions of space and from only few large points clustering together (e.g. few large firms). We refer to this phenomena as to clustering of firms and clustering of economic activities. The present paper aims at tackling this problem by adapting the popular Kfunction (Ripley, 1977) to account for the point dimension using the framework of marked point process theory (Penttinen, 2006)Agglomeration, Marked point processes, Spatial clusters, Spatial econometrics
EspC preferentially targets EspA/EspD-containing structures.
No full text<p>(A-C) Proteins from the supernatant of Δ<i>espC</i> strain were fractionated by anion exchange chromatography, using a linear NaCl gradient. (A) Fractions were analysed by Coomassie blue staining. (B) quantification of the EspA and EspD Coomassie stained bands integrated density in (A). (C) anti-EspA and anti-EspD Western blot analysis. Dashed lines indicate editing between lanes from the same gel. EspB eluted in the flow-through. The first peak containing EspA and EspD eluted at 175nM NaCl (peak A/D), the second peak containing EspA eluted at 290 mM NaCl (peak A). (D, E) Fractions corresponding to peak A or peak A/D were incubated with 40 nM of purified EspC for the indicated time. (D) Western blot analysis using the antibodies indicated on the left. Arrows indicate proteolytic degradation products observed for EspA. (E) quantification of the protein band integrated density. Results are expressed as the mean integrated density ± SEM from at least 3 independent experiments.</p
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