817 research outputs found
Modeling the short-term effect of traffic on air pollution in Torino with generalized additive models
Vehicular traffic typically plays an important role in atmospheric pollution. This is especially true in urban areas, where high pollutant concentrations are often observed. In this paper, we consider hourly measures of concentrations of nitrogen oxides (NO, NO2 and NOx), carbon oxide (CO) and particulate matter (PM), collected at the stations distributed throughout the city of Turin. To help explain the short-term behavior of the concentrations of these pollutants, we propose using generalized additive models (GAM), focusing in particular on traffic along with the meteorological predictors. All the data are collected during the period from December 2003 to April 2005.urban area, air quality, vehicular traffic, CO, NO2, NOx, NO, PM, generalized additive models
Some bounds of loss in classical semideterministic immunization
Since Samuelson, Redington and Fisher and Weil, duration and immunization are very important topics in bond portfolio analysis from both a theoretical and a practical point of view. Many results have been established, especially in semi-deterministic framework. As regards, however, the loss may be sustained, we do not think that the subject has been investigated enough, except for the results found in the wake of the theorem of Fong and Vasicek. In this paper we present some results relating to the limitation of the loss in the case of local immunization for multiple liabilities
Use of a partial least squares regression model to predict Test Day of milk, fat and protein yields in dairy goats
A model able to predict missing test day data for milk, fat and protein yields on the basis of few recorded tests was proposed, based on the partial least squares (PLS) regression technique, a multivariate method that is able to solve problems related to high collinearity among predictors. A data set of 1731 lactations of Sarda breed dairy Goats was split into two data sets, one for model estimation and the other for the evaluation of PLS prediction capability. Eight scenarios of simplified recording schemes for fat and protein yields were simulated. Correlations among predicted and observed test day yields were quite high (from 050 to 088 and from 053 to 096 for fat and protein yields, respectively, in the different scenarios). Results highlight great flexibility and accuracy of this multivariate technique
Gli effetti antropici nell’evoluzione storica della costa “Picena”
The historical evolution of the southern Marche shoreline (between the Conero promontory and the Tronto R. mouth) has been investigated comparing it with both natural and anthropic changes. The study started searching, georeferencing and digitizing in a GIS environment all the available historical maps and the observations deriving from archeological and documental findings, in order to reconstruct the position of the shoreline at different times, mostly for fluvial mouths. This allowed us to highlight that for the last two millennia anthropic interventions influenced coastal dynamics more than climate variations. For all the investigated sites a close relation between shoreline fluctuations and forestation/deforestation processes was clearly revealed.
Among others, it emerged that river mouths progradation continued up to 1930, well after the end of the “Little Ice Age” (around 1850). The above relation is particularly striking for the last two centuries, for which we have both accurate maps and census of forested areas. During the XIX century, notwithstanding the warm climate favored slope protection, widespread deforestation resulted in a regular advance of shorelines (average rate about 4.95 m/y for the first half of the century and 1.08 m/y for the second half). The XX century featured a more irregular behavior with substantial retreat after the ‘30s: this derives almost exclusively from anthropic interventions in the river basins (construction of dams, river bed quarrying, river reshaping, abandonment of crops etc.) leading to a severe decrease of solid load. For the last few decades and at present, the most important factors driving the behavior of coastlines resulted to be the various interventions carried out along the beaches and in front of them to reduce erosion.
Keywords: antropogenic impact, historical evolution, coastline, central-southern Marche, Adriatic Se
Tendenza evolutiva della spiaggia della Riserva Naturale della Sentina (San Benedetto del Tronto, AP)
Abstract
The Regional Natural Reserve “Sentina” stretches itself for some 1.7 km along the southernmost end of the littoral area of San Benedetto del Tronto (AP) at the boundary with Abruzzo; it hosts one of the very few costal dunes still preserved in the Marche Region.
Its gravelly-sandy beach in still natural, but is bound to the north by a long series of emerged barriers and to the south by a long (more than 300 m) pier; these structures noteworthy influence the retreat of the shoreline.
In the area, a long monitoring (starting from 2000) has been carried out in order to interpret and quantify the modification occurred on both the emerged and submerged beach. During this time span, the shoreline retreated every year: up to 2006 its retreat has been evaluated in 27.7 m, with a local maximum of 33.5 m, whilst for the following 6 years (notwithstanding an artificial nourishment in 2008) it continued to retreat by 22.2, as an average. Therefore, in 12 years wave erosion resulted in some 50 m of backing; this also implied the loss of about 42’000 m2 of coastal dunes.
Therefore, it is logical to assume that if no relevant intervention will be carried out, standing the almost absent nourishment deriving from the solid load of the Tronto R., in the next future the Sentina area will suffer progressive coastal erosion, with severe backing of the shoreline and distruction of the coastal dunes.
Keywords: coastal erosion, monitoring, “Sentina” Reserve, coastal dune
Internal Jugular Vein Pyogenic Capillary Hemangioma: A Case Report.
Internal jugular vein hemangioma, also called pyogenic granuloma, is a rare tumor. Such a neoformation was accidentally discovered and excised in a middle-aged man. Histologic and immunohistochemical investigations were performed, and this case is compared with the poor amount of similar ones described in the literatur
Escursione lungo il litorale “piceno”
Abstract
At the end of the National Symposium “Coastal erosion: defense, adaptation or withdrawal?”, organized by the Italian National Group for the Research on Coastal Environment (GNRAC), a short (half day) excursion has been organized to visit the “picena” coast (i.e. the portion of Marche littoral to the south of the Conero Mt.): some key location of which are here synthetically described.
Namely, some of the main features of the coastline in Porto Sant’Elpidio, Porto Recanati and Sirolo are described.
Key words: Adriatic Sea, Marche Region, coastal erosio
Extracellular electrical signals in a neuron-surface junction: model of heterogeneous membrane conductivity
Signals recorded from neurons with extracellular planar sensors have a wide
range of waveforms and amplitudes. This variety is a result of different
physical conditions affecting the ion currents through a cellular membrane. The
transmembrane currents are often considered by macroscopic membrane models as
essentially a homogeneous process. However, this assumption is doubtful, since
ions move through ion channels, which are scattered within the membrane.
Accounting for this fact, the present work proposes a theoretical model of
heterogeneous membrane conductivity. The model is based on the hypothesis that
both potential and charge are distributed inhomogeneously on the membrane
surface, concentrated near channel pores, as the direct consequence of the
inhomogeneous transmembrane current. A system of continuity equations having
non-stationary and quasi-stationary forms expresses this fact mathematically.
The present work performs mathematical analysis of the proposed equations,
following by the synthesis of the equivalent electric element of a
heterogeneous membrane current. This element is further used to construct a
model of the cell-surface electric junction in a form of the equivalent
electrical circuit. After that a study of how the heterogeneous membrane
conductivity affects parameters of the extracellular electrical signal is
performed. As the result it was found that variation of the passive
characteristics of the cell-surface junction, conductivity of the cleft and the
cleft height, could lead to different shapes of the extracellular signals
- …
