Search results for "Statistica"

Fractal dynamics in chaotic quantum transport

2013

Despite several experiments on chaotic quantum transport in two-dimensional systems such as semiconductor quantum dots, corresponding quantum simulations within a real-space model have been out of reach so far. Here we carry out quantum transport calculations in real space and real time for a two-dimensional stadium cavity that shows chaotic dynamics. By applying a large set of magnetic fields we obtain a complete picture of magnetoconductance that indicates fractal scaling. In the calculations of the fractality we use detrended fluctuation analysis -- a widely used method in time series analysis -- and show its usefulness in the interpretation of the conductance curves. Comparison with a s…

How news affect the trading behavior of different categories of investors in a financial market

2015

We investigate the trading behavior of a large set of single investors trading the highly liquid Nokia stock over the period 2003-2008 with the aim of determining the relative role of endogenous and exogenous factors that may affect their behavior. As endogenous factors we consider returns and volatility, whereas the exogenous factors we use are the total daily number of news and a semantic variable based on a sentiment analysis of news. Linear regression and partial correlation analysis of data show that different categories of investors are differently correlated to these factors. Governmental and non profit organizations are weakly sensitive to news and returns or volatility, and, typica…

The relationship between context, structure, and processes with outcomes of 6 regional diabetes networks in Europe

2018

BackgroundWhile health service provisioning for the chronic condition Type 2 Diabetes (T2D) often involves a network of organisations and professionals, most evidence on the relationships between the structures and processes of service provisioning and the outcomes considers single organisations or solo practitioners. Extending Donabedian's Structure-Process-Outcome (SPO) model, we investigate how differences in quality of life, effective coverage of diabetes, and service satisfaction are associated with differences in the structures, processes, and context of T2D services in six regions in Finland, Germany, Greece, Netherlands, Spain, and UK.MethodsData collection consisted of: a) systemat…

Indistinguishability of Elementary Systems as a Resource for Quantum Information Processing.

2017

Typical elements of quantum networks are made by identical systems, which are the basic particles constituting a resource for quantum information processing. Whether the indistinguishability due to particle identity is an exploitable quantum resource remains an open issue. Here we study independently prepared identical particles showing that, when they spatially overlap, an operational entanglement exists which can be made manifest by means of separated localized measurements. We prove this entanglement is physical in that it can be directly exploited to activate quantum information protocols, such as teleportation. These results establish that particle indistinguishability is a utilizable …

Evaluation of alveolar cortical bone thickness and density for orthodontic mini-implant placement.

2013

Objective: Mini-implant stability is primarily related to bone quality and quantity. This study evaluated alveolar cortical bone thickness and density differences between interradicular sites at different levels from the alveolar crest, and assessed the differences between adolescents (12-18 years of age) and adults (19-50 years of age), males and females, upper and lower arch, anterior and posterior region of jaws and buccal and oral side. Study Design: In this retrospective study, 48 Computed Tomography scans, performed for oral surgery purposes were selected from dental records of 3,223 Caucasian orthodontic patients. The SimPlant software (Materialise, Leuven, Belgium) was used to measu…

La falta de reproducibilitat de la investigació: L'estadística com a legitimació del resultat

2014

La investigació científica es legitima mitjançant la replicació dels seus resultats, però els esforços per replicar afirmacions enganyoses exhaureixen el finançament. Ens centrarem en una d’aquestes errades: els resultats de proves estadístiques que ofereixen falsos positius a causa de l’atzar. Els mètodes estadístics clàssics confien en un p-valor per a ponderar les proves enfront d’una hipòtesi nul·la, però les proves d’hipòtesis bayesianes ofereixen resultats més fàcils de comprendre, sempre que hom puga especificar distribucions a priori per a la hipòtesi alternativa. Descriurem noves proves, les UMPBT, tests bayesians que ofereixen una especificació per defecte de les alternatives a pr…

Palvelunestohyökkäysten havainnointi ja torjuminen tilastollisilla menetelmillä

2015

Palvelunestohyökkäykset ovat ajankohtaisena ongelmana tärkeä tutkimuksen kohde. Palvelunestohyökkäysten torjumiseen tarvitaan menetelmiä, joilla palvelua kuormittava hyökkäysliikenne voidaan erottaa tavallisesta verkkoliikenteestä. Tämän tutkimuksen tavoitteena on perehtyä palvelunestohyökkäysten toimintaan ja selvittää, mitä tilastollisia torjumismenetelmiä hyökkäysten torjumiseen käytetään. Tutkimuksessa selvitettiin palvelunestohyökkäysten yleiset pääpiirteet ja luokiteltiin hyökkäykset kahteen pääluokkaan. Lisäksi tutkimuksessa tunnistettiin neljä eri tilastollista torjumismenetelmää. Palvelunestohyökkäysten torjuminen on haasteellista, eikä yleiskäyttöistä torjumismenetelmää ole kehite…

Viaggi multi destinazione e turismo sommerso: l'indagine sul turismo incoming in Sicilia

2013

From South to North? Mobility of Southern Italian Students at the Transition from the First to the Second Level University Degree

2018

In the last decades, the Italian University System has encountered several structural reforms aimed at making it more internationally competitive. Among them, the introduction of the University financial autonomy has triggered an “internal” competition among Universities to attract students from the entire country. Students’ enrollment at the first level has decreased significantly especially after the economic crisis of 2008, while the students’ migration from the South to the Central and Northern regions of the country has increased. These phenomena have created further inequalities within the country and a cultural and socio-economic loss for the South that does not appear to slow down. …

Coherent conditional probabilities and proper scoring rules

2011

In this paper we study the relationship between the notion of coherence for conditional probability assessments on a family of conditional events and the notion of admissibility with respect to scoring rules. By extending a recent result given in literature for unconditional events, we prove, for any given strictly proper scoring rule s, the equivalence between the coherence of a conditional probability assessment and its admissibility with respect to s. In this paper we focus our analysis on the case of continuous bounded scoring rules. In this context a key role is also played by Bregman divergence and by a related theoretical aspect. Finally, we briefly illustrate a possible way of defin…