7,536 research outputs found
On the radiality of constrained minimizers to the Schroedinger-Poisson-Slater energy
We study the radial symmetry of minimizers to the Schroedinger-Poisson-Slater
(S-P-S) energy
The role of financing in international trade during good times and bad
The collapse of trade during the financial crisis can be tied, for the most part, to a drop in demand. Less talked about, however, is the role of financing—or lack thereof.International trade
Landscapes of data sets and functoriality of persistent homology
The aim of this article is to describe a new perspective on functoriality of
persistent homology and explain its intrinsic symmetry that is often
overlooked. A data set for us is a finite collection of functions, called
measurements, with a finite domain. Such a data set might contain internal
symmetries which are effectively captured by the action of a set of the domain
endomorphisms. Different choices of the set of endomorphisms encode different
symmetries of the data set. We describe various category structures on such
enriched data sets and prove some of their properties such as decompositions
and morphism formations. We also describe a data structure, based on coloured
directed graphs, which is convenient to encode the mentioned enrichment. We
show that persistent homology preserves only some aspects of these landscapes
of enriched data sets however not all. In other words persistent homology is
not a functor on the entire category of enriched data sets. Nevertheless we
show that persistent homology is functorial locally. We use the concept of
equivariant operators to capture some of the information missed by persistent
homology
Transcriptome dynamics in the asexual cycle of the chordate Botryllus schlosseri
Background: We performed an analysis of the transcriptome during the blastogenesis of the chordate Botryllus
schlosseri, focusing in particular on genes involved in cell death by apoptosis. The tunicate B. schlosseri is an ascidian
forming colonies characterized by the coexistence of three blastogenetic generations: filter-feeding adults, buds on
adults, and budlets on buds. Cyclically, adult tissues undergo apoptosis and are progressively resorbed and replaced
by their buds originated by asexual reproduction. This is a feature of colonial tunicates, the only known chordates
that can reproduce asexually.
Results: Thanks to a newly developed web-based platform (http://botryllus.cribi.unipd.it), we compared the
transcriptomes of the mid-cycle, the pre-take-over, and the take-over phases of the colonial blastogenetic
cycle. The platform is equipped with programs for comparative analysis and allows to select the statistical
stringency. We enriched the genome annotation with 11,337 new genes; 581 transcripts were resolved as
complete open reading frames, translated in silico into amino acid sequences and then aligned onto the
non-redundant sequence database. Significant differentially expressed genes were classified within the gene
ontology categories. Among them, we recognized genes involved in apoptosis activation, de-activation, and
regulation.
Conclusions: With the current work, we contributed to the improvement of the first released B. schlosseri
genome assembly and offer an overview of the transcriptome changes during the blastogenetic cycle,
showing up- and down-regulated genes. These results are important for the comprehension of the events
underlying colony growth and regression, cell proliferation, colony homeostasis, and competition among
different generations
Semi-Parametric Empirical Best Prediction for small area estimation of unemployment indicators
The Italian National Institute for Statistics regularly provides estimates of
unemployment indicators using data from the Labor Force Survey. However, direct
estimates of unemployment incidence cannot be released for Local Labor Market
Areas. These are unplanned domains defined as clusters of municipalities; many
are out-of-sample areas and the majority is characterized by a small sample
size, which render direct estimates inadequate. The Empirical Best Predictor
represents an appropriate, model-based, alternative. However, for non-Gaussian
responses, its computation and the computation of the analytic approximation to
its Mean Squared Error require the solution of (possibly) multiple integrals
that, generally, have not a closed form. To solve the issue, Monte Carlo
methods and parametric bootstrap are common choices, even though the
computational burden is a non trivial task. In this paper, we propose a
Semi-Parametric Empirical Best Predictor for a (possibly) non-linear mixed
effect model by leaving the distribution of the area-specific random effects
unspecified and estimating it from the observed data. This approach is known to
lead to a discrete mixing distribution which helps avoid unverifiable
parametric assumptions and heavy integral approximations. We also derive a
second-order, bias-corrected, analytic approximation to the corresponding Mean
Squared Error. Finite sample properties of the proposed approach are tested via
a large scale simulation study. Furthermore, the proposal is applied to
unit-level data from the 2012 Italian Labor Force Survey to estimate
unemployment incidence for 611 Local Labor Market Areas using auxiliary
information from administrative registers and the 2011 Census
I lieviti del Vino Fiano di Avellino DOCG: la tipicitĂ attraverso le biotecnologie
I microrganismi caratteristici di un prodotto tipico fermentato come il vino, dai quali dipendono molte delle proprietà organolettiche, riflettono, in molti casi, le caratteristiche dell’ambiente e dei sistemi di produzione. Infatti, i prodotti alimentari di nicchia legano la loro storia alla zona di produzione non solo per le tradizioni che si tramandano nel tempo, ma anche e soprattutto per la presenza di specie e ceppi di microrganismi che colonizzano la materia prima, nonché gli ambienti e le attrezzature di lavorazione, contribuendo in maniera decisiva a caratterizzare la tipicità del prodotto finale.
Nello spirito delle “Denominazioni d’Origine”, particolare importanza deve essere ancora attribuita a tutti quegli elementi che creano il “legame” tra un determinato prodotto e una particolare zona geografica, la cultura della popolazione e tutti quegli aspetti che possono essere sintetizzati nell’insieme dei fattori storico-sociali nei quali risiedono i motivi dello sviluppo di un prodotto in una data area antropizzata. I microrganismi rientrano sicuramente tra questi fattori e costituiscono, anzi, uno dei “segreti” dei produttori artigianali che, nel tempo, sono stati svelati e convertiti in moderna tecnologia di trasformazione.
Anche l’impiego di ceppi “autoctoni”, selezionati durante la trasformazione di prodotti tradizionali e legati allo sviluppo di componenti aromatiche desiderate, al prolungamento della shelf-life, agli aspetti salutistici dei prodotti finiti e cosìvia, può richiedere l’adattamento di protocolli produttivi già esistenti per migliorare le performance del(i) microrganismo(i). Tuttavia, tale innovazione non può essere “selvaggia”, bensì dovrebbe essere rispettosa degli aspetti essenziali e peculiari della tradizione di un prodotto. In questo lavoro svolto nell'areale del Fiano di Avellino DOCG si sono selezionati dall'ambiente vigneto 2 ceppi di Saccharomyces cerevisiae da utilizzare come starter nella produzione di qualità del vino Fian
DIBRAST: A Computer-Aided Seismic Design Procedure for Frame Structures Equipped With Hysteretic Devices
This paper describes a comprehensive computer-aided seismic design approach for both new and existing frame structures equipped with hysteretic dampers. Despite continuous advancements in the state of the art demonstrating the effectiveness of these devices in mitigating seismic hazard, non-linearities involved in the problem and the articulated nature of most of the available design procedures often make them quite difficult to be implemented for real complex structures. To promote widespread use of hysteretic dampers, we present a thorough design approach that includes the application of a specific displacement-based design procedure by means of a computer-aided support tool developed in a Visual Basic environment and named DIBRAST. The software is realized to drive the designer through the dissipative system's design. Required iterations are automated, thus significantly reducing the processing time. As its final output, it delivers the mechanical properties of the damping braces in order to meet a specific performance objective. In order to further support practitioners in the geometrical characterization of actual design dampers, authors developed an additional Visual Basic tool—the Shear Link Non-Linear Model—that is able to provide yielding force and elastic stiffness of a specific type of hysteretic device according to its geometry and material. In addition, geometric details of each device can be preliminary determined by means of newly proposed design charts, presented herein, that allow us to take into account the buckling issue too. Both developed tools are freely available online. A case study is provided to demonstrate the effectiveness of the proposed design approach and tools
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