Search results for "Database"
showing 10 items of 2136 documents
Regression with Imputed Covariates: A Generalized Missing Indicator Approach
2011
A common problem in applied regression analysis is that covariate values may be missing for some observations but imputed values may be available. This situation generates a trade-off between bias and precision: the complete cases are often disarmingly few, but replacing the missing observations with the imputed values to gain precision may lead to bias. In this paper we formalize this trade-off by showing that one can augment the regression model with a set of auxiliary variables so as to obtain, under weak assumptions about the imputations, the same unbiased estimator of the parameters of interest as complete-case analysis. Given this augmented model, the bias-precision trade-off may then…
Current Software-as-a-Service Business Models: Evidence from Finland
2012
This paper characterizes the business models of Software-as-a-Service (SaaS) firms based on their value proposition, customer segments, revenue streams, and customer relationship, and analyzes interconnections of these business model elements. The target set of 163 Finnish SaaS and ASP firms was first compared to other software firms and then clustered into four clusters based on indicator data of their business model elements. The comparison reveals that the SaaS and ASP firms have smaller customer and transaction sizes than software firms in general. The resulting classification reveals two different configurations, a pure-play SaaS model and an enterprise SaaS model, and the typical fact…
Detection and Isolation of Switches in Point Clouds of the German Railway Network
2015
In order to obtain an automated system of railway management, it is necessary to automatically detect, isolate and identify all switches in a point cloud which represents the railway. To realize this automated system of detection, a set of pre-processing steps is applied. The system begins by detecting and isolating tracks through application of a mask on each section of the point cloud. Then, it does a denoising through mathematical morphology and a compression in replacing a group of points by their centroid. Finally, it closes tracks holes through extrapolation. After that, the system does a low-level processing to search for all intersections between tracks, and records information on t…
DEVELOPMENT OF AN OLIVE PHENOLOGICAL MODEL IN RELATION TO AIR TEMPERATURE
2008
The effect of air temperature on olive phenological development has not been extensively studied. Indirectly related data are available, mostly from air pollen concentration measurements rather than direct observation of phenological stages. Data on phenological stages of olive collected in Sicily, by the Sicilian Agrometeorological Service (SIAS), in 10 locations characterized by different climatic conditions were used to develop and calibrate a phenological model for the most important developmental stages in olive. Phenological stages under study were: bud break, inflorescence emission, and full bloom A base-temperature linear model was developed by choosing a temperature threshold using…
Essential Oils as Nematicides in Plant Protection-A Review
2023
By 2030, the European Commission intends to halve chemical pesticide use and its consequent risks. Among pesticides, nematicides are chemical agents used to control parasitic roundworms in agriculture. In recent decades, researchers have been looking for more sustainable alternatives with the same effectiveness but a limited impact on the environment and ecosystems. Essential oils (EOs) are similar bioactive compounds and potential substitutes. Different studies on the use of EOs as nematicides are available in the Scopus database in the scientific literature. These works show a wider exploration of EO effects in vitro than in vivo on different nematode populations. Nevertheless, a review o…
Suoli d'Italia: minacce, stato ed efficacia delle risposte
2011
La degradazione del suolo è uno degli aspetti più rilevanti del cambiamento globale e la vulnerabilità dei terreni italiani ai processi di degradazione è certamente superiore ad altri paesi europei, a causa delle caratteristiche specifiche e dell’ alta variabilità delle condizioni ambientali.Oltre alle cause naturali, la degradazione del suolo è spesso causata dall'effetto delle attività umane ed in particolare all'utilizzazione delle terre non corretta. Le informazioni memorizzate nella base di dati nazionale del suolo sono state usate per un primo controllo della qualità dei suoli italiani e degli effetti delle politiche gestionali. La banca dati è costituita da un database, contenente in…
Five key attributes can increase marine protected areas performance for small-scale fisheries management
2016
AbstractMarine protected areas (MPAs) have largely proven to be effective tools for conserving marine ecosystem, while socio-economic benefits generated by MPAs to fisheries are still under debate. Many MPAs embed a no-take zone, aiming to preserve natural populations and ecosystems, within a buffer zone where potentially sustainable activities are allowed. Small-scale fisheries (SSF) within buffer zones can be highly beneficial by promoting local socio-economies. However, guidelines to successfully manage SSFs within MPAs, ensuring both conservation and fisheries goals, and reaching a win-win scenario, are largely unavailable. From the peer-reviewed literature, grey-literature and intervie…
L'isola delle cento leggende
2022
L’isola delle cento leggende. Così Andrea Pittiruti presenta, al pubblico televisivo della RAI nel 1962, Ustica, nuovo approdo del turismo internazionale. Un documentario che ripercorre la storia dell’isola, dall’originario insediamento fenicio alla prima colonizzazione del XIII sec., dalle scorribande saracene al 19 maggio 1961 giorno in cui si chiude la triste parentesi del confino politico (attivo dal 1926). Le ricerche e le esperienze didattiche del Laboratorio di Visual e Graphic Design e Web Design, corso integrato del Corso di laurea magistrale in Design e Cultura del Territorio, nel Dipartimento di Architettura dell’Università degli Studi di Palermo, dal 2018 al 2021 esplorano quest…
Dissimilarity Measures for the Identification of Earthquake Focal Mechanisms
2013
This work presents a study about dissimilarity measures for seismic signals, and their relation to clustering in the particular problem of the identification of earthquake focal mechanisms, i.e. the physical phenomena which have generated an earthquake. Starting from the assumption that waveform similarity implies similarity in the focal parameters, important details about them can be determined by studying waveforms related to the wave field produced by earthquakes and recorded by a seismic network. Focal mechanisms identification is currently investigated by clustering of seismic events, using mainly cross-correlation dissimilarity in conjunction with hierarchical clustering algorithm. By…
Mobile agent application fields
2004
Publisher Summary Mobile agents are a recent paradigm for software design, which extends object oriented programming features. An agent can perform its task autonomously; a mobile agent can carry out complex tasks that require the agent to migrate from a network place to another one. Mobile agent application fields are many. It can replace web services in other cases, mobile agents and web services can be an effective solution together. The chapter discusses the three mobile agent application fields, which are: parallel and distributed computing, data mining and information retrieval, and networking. An overview of the development platforms is also discussed. Data mining and information ret…