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  1. Article: A new measure for the attitude to mobility of Italian students and graduates: a topological data analysis approach.

    Vittorietti, Martina / Giambalvo, Ornella / Genova, Vincenzo Giuseppe / Aiello, Fabio

    Statistical methods & applications

    2022  , Page(s) 1–35

    Abstract: Students' and graduates' mobility is an interesting topic of discussion especially for the Italian education system and universities. The main reasons for migration and for the so called brain drain, can be found in the socio-economic context and in the ... ...

    Abstract Students' and graduates' mobility is an interesting topic of discussion especially for the Italian education system and universities. The main reasons for migration and for the so called brain drain, can be found in the socio-economic context and in the famous North-South divide. Measuring mobility and understanding its dynamic over time and space are not trivial tasks. Most of the studies in the related literature focus on the determinants of such phenomenon, in this paper, instead, combining tools coming from graph theory and Topological Data Analysis we propose a new measure for the attitude to mobility. Each mobility trajectory is represented by a graph and the importance of the features constituting the graph are evaluated over time using persistence diagrams. The attitude to mobility of the students is then ranked computing the distance between the individual persistence diagram and the theoretical persistence diagram of the stayer student. The new approach is used for evaluating the mobility of the students that in 2008 enrolled in an Italian university. The relation between attitude to mobility and the main socio-demographic variables is investigated.
    Language English
    Publishing date 2022-10-24
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2098826-6
    ISSN 1613-981X ; 1618-2510
    ISSN (online) 1613-981X
    ISSN 1618-2510
    DOI 10.1007/s10260-022-00666-x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Microstructure–property relation and machine learning prediction of hole expansion capacity of high-strength steels

    Li, Wei / Vittorietti, Martina / Jongbloed, Geurt / Sietsma, Jilt

    Journal of materials science. 2021 Dec., v. 56, no. 34

    2021  

    Abstract: The relationship between microstructure features and mechanical properties plays an important role in the design of materials and improvement of properties. Hole expansion capacity plays a fundamental role in defining the formability of metal sheets. Due ...

    Abstract The relationship between microstructure features and mechanical properties plays an important role in the design of materials and improvement of properties. Hole expansion capacity plays a fundamental role in defining the formability of metal sheets. Due to the complexity of the experimental procedure of testing hole expansion capacity, where many influencing factors contribute to the resulting values, the relationship between microstructure features and hole expansion capacity and the complexity of this relation is not yet fully understood. In the present study, an experimental dataset containing the phase constituents of 55 microstructures as well as corresponding properties, such as hole expansion capacity and yield strength, is collected from the literature. Statistical analysis of these data is conducted with the focus on hole expansion capacity in relation to individual phases, combinations of phases and number of phases. In addition, different machine learning methods contribute to the prediction of hole expansion capacity based on both phase fractions and chemical content. Deep learning gives the best prediction accuracy of hole expansion capacity based on phase fractions and chemical composition. Meanwhile, the influence of different microstructure features on hole expansion capacity is revealed.
    Keywords chemical composition ; data collection ; microstructure ; prediction ; statistical analysis
    Language English
    Dates of publication 2021-12
    Size p. 19228-19243.
    Publishing place Springer US
    Document type Article
    ZDB-ID 2015305-3
    ISSN 1573-4803 ; 0022-2461
    ISSN (online) 1573-4803
    ISSN 0022-2461
    DOI 10.1007/s10853-021-06496-8
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Isotonic regression for metallic microstructure data: estimation and testing under order restrictions.

    Vittorietti, Martina / Hidalgo, Javier / Sietsma, Jilt / Li, Wei / Jongbloed, Geurt

    Journal of applied statistics

    2021  Volume 49, Issue 9, Page(s) 2208–2227

    Abstract: Investigating the main determinants of the mechanical performance of metals is not a simple task. Already known physically inspired qualitative relations between 2D microstructure characteristics and 3D mechanical properties can act as the starting point ...

    Abstract Investigating the main determinants of the mechanical performance of metals is not a simple task. Already known physically inspired qualitative relations between 2D microstructure characteristics and 3D mechanical properties can act as the starting point of the investigation. Isotonic regression allows to take into account ordering relations and leads to more efficient and accurate results when the underlying assumptions actually hold. The main goal in this paper is to test order relations in a model inspired by a materials science application. The statistical estimation procedure is described considering three different scenarios according to the knowledge of the variances: known variance ratio, completely unknown variances, and variances under order restrictions. New likelihood ratio tests are developed in the last two cases. Both parametric and non-parametric bootstrap approaches are developed for finding the distribution of the test statistics under the null hypothesis. Finally an application on the relation between geometrically necessary dislocations and number of observed microstructure precipitations is shown.
    Language English
    Publishing date 2021-03-05
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476802-1
    ISSN 1360-0532 ; 0266-4763
    ISSN (online) 1360-0532
    ISSN 0266-4763
    DOI 10.1080/02664763.2021.1896685
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: A Data-Driven Approach for Studying the Influence of Carbides on Work Hardening of Steel.

    Vittorietti, Martina / Hidalgo, Javier / Galán López, Jesús / Sietsma, Jilt / Jongbloed, Geurt

    Materials (Basel, Switzerland)

    2022  Volume 15, Issue 3

    Abstract: This study proposes a new approach to determine phenomenological or physical relations between microstructure features and the mechanical behavior of metals bridging advanced statistics and materials science in a study of the effect of hard precipitates ... ...

    Abstract This study proposes a new approach to determine phenomenological or physical relations between microstructure features and the mechanical behavior of metals bridging advanced statistics and materials science in a study of the effect of hard precipitates on the hardening of metal alloys. Synthetic microstructures were created using multi-level Voronoi diagrams in order to control microstructure variability and then were used as samples for virtual tensile tests in a full-field crystal plasticity solver. A data-driven model based on Functional Principal Component Analysis (FPCA) was confronted with the classical Voce law for the description of uniaxial tensile curves of synthetic AISI 420 steel microstructures consisting of a ferritic matrix and increasing volume fractions of M23C6 carbides. The parameters of the two models were interpreted in terms of carbide volume fractions and texture using linear mixed-effects models.
    Language English
    Publishing date 2022-01-24
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma15030892
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Implant replacement and anaplastic large cell lymphoma associated with breast implants: a quantitative analysis.

    Vittorietti, Martina / Mazzola, Sergio / Costantino, Claudio / De Bella, Daniele Domenico / Fruscione, Santo / Bonaccorso, Nicole / Sciortino, Martina / Costanza, Davide / Belluzzo, Miriam / Savatteri, Alessandra / Tramuto, Fabio / Contiero, Paolo / Tagliabue, Giovanna / Immordino, Palmira / Vitale, Francesco / Di Napoli, Arianna / Mazzucco, Walter

    Frontiers in oncology

    2023  Volume 13, Page(s) 1202733

    Abstract: Introduction: Breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL) is a rare form of non-Hodgkin T-cell lymphoma associated with breast reconstruction post-mastectomy or cosmetic-additive mammoplasty. The increasing use of implants for ... ...

    Abstract Introduction: Breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL) is a rare form of non-Hodgkin T-cell lymphoma associated with breast reconstruction post-mastectomy or cosmetic-additive mammoplasty. The increasing use of implants for cosmetic purposes is expected to lead to an increase in BIA-ALCL cases. This study investigated the main characteristics of the disease and the factors predicting BIA-ALCL onset in patients with and without an implant replacement.
    Methods: A quantitative analysis was performed by two independent researchers on cases extracted from 52 primary studies (case report, case series, and systematic review) published until April 2022 and searched in PubMed, Scopus, and Google-Scholar databases using "Breast-Implant" AND/OR "Associated" AND/OR "Anaplastic-Large-Cell-Lymphoma". The statistical significance was verified by Student's
    Results: Overall, 232 patients with BIA-ALCL were extracted. The mean age at diagnosis was 55 years old, with a mean time to disease onset from the first implant of 10.3 years. The hazard of developing BIA-ALCL in a shorter time resulted significantly higher for patients not having an implant replacement (hazard ratio = 0.03; 95%CI: 0.005-0.19;
    Discussion: Our findings suggest that, in BIA-ALCL patients, the implant substitution and/or capsulectomy may delay the disease's onset. However, the risk of reoccurrence in an earlier time should be considered in these patients. Moreover, the time to BIA-ALCL onset slightly increased with age. Selection bias, lack of awareness, misdiagnosis, and limited data availability could be identified as limits of our study. An implant replacement should be considered according to a risk stratification approach to delay the BIA-ALCL occurrence in asymptomatic patients, although a stricter follow-up after the implant substitution should be recommended.
    Systematic review registration: https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42023446726.
    Language English
    Publishing date 2023-10-19
    Publishing country Switzerland
    Document type Systematic Review
    ZDB-ID 2649216-7
    ISSN 2234-943X
    ISSN 2234-943X
    DOI 10.3389/fonc.2023.1202733
    Database MEDical Literature Analysis and Retrieval System OnLINE

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