Search results for "NULL"

Detecting informative higher-order interactions in statistically validated hypergraphs

2021

Recent empirical evidence has shown that in many real-world systems, successfully represented as networks, interactions are not limited to dyads, but often involve three or more agents at a time. These data are better described by hypergraphs, where hyperlinks encode higher-order interactions among a group of nodes. In spite of the large number of works on networks, highlighting informative hyperlinks in hypergraphs obtained from real world data is still an open problem. Here we propose an analytic approach to filter hypergraphs by identifying those hyperlinks that are over-expressed with respect to a random null hypothesis, and represent the most relevant higher-order connections. We apply…

Community characterization of heterogeneous complex systems

2011

We introduce an analytical statistical method to characterize the communities detected in heterogeneous complex systems. By posing a suitable null hypothesis, our method makes use of the hypergeometric distribution to assess the probability that a given property is over-expressed in the elements of a community with respect to all the elements of the investigated set. We apply our method to two specific complex networks, namely a network of world movies and a network of physics preprints. The characterization of the elements and of the communities is done in terms of languages and countries for the movie network and of journals and subject categories for papers. We find that our method is ab…

Can visualization alleviate dichotomous thinking? Effects of visual representations on the cliff effect

2021

Common reporting styles for statistical results in scientific articles, such as $p$ p -values and confidence intervals (CI), have been reported to be prone to dichotomous interpretations, especially with respect to the null hypothesis significance testing framework. For example when the $p$ p -value is small enough or the CIs of the mean effects of a studied drug and a placebo are not overlapping, scientists tend to claim significant differences while often disregarding the magnitudes and absolute differences in the effect sizes. This type of reasoning has been shown to be potentially harmful to science. Techniques relying on the visual estimation of the strength of evidence have been recom…

Empirical Analyses of Networks in Finance

2018

Abstract The recent global financial crisis has triggered a huge interest in the use of network concepts and network tools to better understand how instabilities can propagate through the financial system. The literature is today quite vast, covering both theoretical and empirical aspects. This review concentrates on empirical work, and associated methodologies, concerned with the evaluation of the fragility and resilience of financial and credit markets. The first part of the review examines the literature on systemic risk that arise from banks mutual exposures. These exposures stem primarily from interbank lending and derivative positions, but also, indirectly, from common holdings of oth…

Unidirectional probabilistic direct control for deferrable loads

2014

International audience; The idea of harnessing the inherent flexibility in demand of many types of electric loads has been largely discussed in the last years for coping with the need to maintain the energy demand-supply balance. In particular, the fine tuning of the operation conditions of different thermostatic loads (such as air-conditioning, refrigerators, etc.) has appeared as the most natural solution for load control with minimal user discomfort. In this paper we focus on an alternative approach: deploying simple open-loop control strategies for deferrable loads with minimal communication overhead. The idea is to send a multicast control message to a group of users, on the basis of t…

Letture di giurisprudenza.

2009

Cass. Sezioni Unite 18214/2015: i giudici di legittimità sulla «interpretazione assiologicamente orientata» delle nullità per vizio di forma

2015

Confermando il trend ormai piuttosto nitido che vuole il tema del formalismo negoziale il più interessante laboratorio di nullità speciali, la sentenza delle Sezioni Unite qui brevemente commentata aggiunge un tassello non trascurabile né scontato ad un dibattito ancora vivace: non tanto o non solo per l’esito cui perviene nella circoscritta materia della locazione abitativa, quanto piuttosto per la disinvoltura con cui maneggia un argomento decisamente «caldo» del diritto dei contratti. La prima questione su cui è chiamata a pronunciarsi la Corte è di facile soluzione ma di articolata argomentazione: se per le locazioni di immobili adibiti ad uso abitativo di cui alla legge n. 431/1998 la …

Curve packing and modulus estimates

2018

A family of planar curves is called a Moser family if it contains an isometric copy of every rectifiable curve in $\mathbb{R}^{2}$ of length one. The classical "worm problem" of L. Moser from 1966 asks for the least area covered by the curves in any Moser family. In 1979, J. M. Marstrand proved that the answer is not zero: the union of curves in a Moser family has always area at least $c$ for some small absolute constant $c > 0$. We strengthen Marstrand's result by showing that for $p > 3$, the $p$-modulus of a Moser family of curves is at least $c_{p} > 0$.

A Nullclines Approach to the Study of 2D Artificial Network

2019


 
 The system of two the first order ordinary differential equations arising in the gene regulatory networks theory is studied. The structure of attractors for this system is described for three important behavioral cases: activation, inhibition, mixed activation-inhibition. The geometrical approach combined with the vector field analysis allows treating the problem in full generality. A number of propositions are stated and the proof is geometrical, avoiding complex analytic. Although not all the possible cases are considered, the instructions are given what to do in any particular situation.

Genetic characterisation of CSN2 gene in Girgentana goat breed

2014

Among calcium sensitive caseins, β-casein is the most abundant in goat milk, representing up to 50% of total casein content. The goat β-casein locus has been widely investigated and at least ten alleles have been identified in different goat breeds. The aim of this work was to investigate the polymorphisms of β-casein gene in Girgentana dairy goat breed in order to assess the genotype distribution and evaluate how frequencies have changed during the last 10 years, as genotype is known to influence technological and nutritional milk properties. Sequencing analysis and alignment of the obtained sequences of β-casein exon 7, showed the presence of C, C1, and A strong alleles, and 0' null allel…