Littérature scientifique sur le sujet « Vanni Rossi »

D'Angelo, Egidio, Giovanna De Filippi, Paola Rossi, and Vanni Taglietti. Ionic mechanism of electroresponsiveness in cerebellar granule cells implicates the action of a persistent sodium current. J. Neurophysiol. 80: 493–503, 1998. Although substantial knowledge has been accumulated on cerebellar granule cell voltage-dependent currents, their role in regulating electroresponsiveness has remained speculative. In this paper, we have used patch-clamp recording techniques in acute slice preparations to investigate the ionic basis of electroresponsiveness of rat cerebellar granule cells at a mature developmental stage. The granule cell generated a Na+-dependent spike discharge resistant to voltage and time inactivation, showing a linear frequency increase with injected currents. Action potentials arose when subthreshold depolarizing potentials, which were driven by a persistent Na+ current, reached a critical threshold. The stability and linearity of the repetitive discharge was based on a complex mechanism involving a N-type Ca2+ current blocked by ω-CTx GVIA, and a Ca2+-dependent K+ current blocked by charibdotoxin and low tetraethylammonium (TEA; <1 mM); a voltage-dependent Ca2+-independent K+ current blocked by high TEA (>1 mM); and an A current blocked by 2 mM 4-aminopyridine. Weakening TEA-sensitive K+ currents switched the granule cell into a bursting mode sustained by the persistent Na+ current. A dynamic model is proposed in which the Na+ current-dependent action potential causes secondary Ca2+ current activation and feedback voltage- and Ca2+-dependent afterhyperpolarization. The afterhyperpolarization reprimes the channels inactivated in the spike, preventing adaptation and bursting and controlling the duration of the interspike interval and firing frequency. This result reveals complex dynamics behind repetitive spike discharge and suggests that a persistent Na+ current plays an important role in action potential initiation and in the regulation of mossy fiber-granule cells transmission.

D'Angelo, Egidio, Paola Rossi, Simona Armano, and Vanni Taglietti. Evidence for NMDA and mGlu receptor-dependent long-term potentiation of mossy fiber–granule cell transmission in rat cerebellum. J. Neurophysiol. 81: 277–287, 1999. Long-term potentiation (LTP) is a form of synaptic plasticity that can be revealed at numerous hippocampal and neocortical synapses following high-frequency activation of N-methyl-d-aspartate (NMDA) receptors. However, it was not known whether LTP could be induced at the mossy fiber–granule cell relay of cerebellum. This is a particularly interesting issue because theories of the cerebellum do not consider or even explicitly negate the existence of mossy fiber–granule cell synaptic plasticity. Here we show that high-frequency mossy fiber stimulation paired with granule cell membrane depolarization (−40 mV) leads to LTP of granule cell excitatory postsynaptic currents (EPSCs). Pairing with a relatively hyperpolarized potential (−60 mV) or in the presence of NMDA receptor blockers [5-amino-d-phosphonovaleric acid (APV) and 7-chloro-kynurenic acid (7-Cl-Kyn)] prevented LTP, suggesting that the induction process involves a voltage-dependent NMDA receptor activation. Metabotropic glutamate receptors were also involved because blocking them with (+)-α-methyl-4-carboxyphenyl-glycine (MCPG) prevented potentiation. At the cytoplasmic level, EPSC potentiation required a Ca2+ increase and protein kinase C (PKC) activation. Potentiation was expressed through an increase in both the NMDA and non-NMDA receptor-mediated current and by an NMDA current slowdown, suggesting that complex mechanisms control synaptic efficacy during LTP. LTP at the mossy fiber–granule cell synapse provides the cerebellar network with a large reservoir for memory storage, which may be needed to optimize pattern recognition and, ultimately, cerebellar learning and computation.

D'Angelo, Egidio, Giovanna De Filippi, Paola Rossi, and Vanni Taglietti. Synaptic activation of Ca2+ action potentials in immature rat cerebellar granule cells in situ. J. Neurophysiol. 78: 1631–1642, 1997. Although numerous Ca2+ channels have been identified in cerebellar granule cells, their role in regulating excitability remained unclear. We therefore investigated the excitable response in granule cells using whole cell patch-clamp recordings in acute rat cerebellar slices throughout the time of development (P4–P21, n = 183), with the aim of identifying the role of Ca2+ channels and their activation mechanism. After depolarizing current injection, 46% of granule cells showed Ca2+ action potentials, whereas repetitive Na+ spikes were observed in an increasing proportion of granule cells from P4 to P21. Because Ca2+ action potentials were no longer observed after P21, they characterized an immature granule cell functional stage. Ca2+ action potentials consisted of an intermediate-threshold spike (ITS) activating at −60/−50 mV and sensitive to voltage inactivation and of a high-threshold spike (HTS), activating at above −30 mV and resistant to voltage inactivation. Both ITS and HTS comprised transient and protracted Ca2+ channel-dependent depolarizations. The Ca2+ action potentials could be activated synaptically by excitatory postsynaptic potentials, which were significantly slower and had a proportionately greater N-methyl-d-aspartate (NMDA) receptor-mediated component than those recorded in cells with fast repetitive Na+ spikes. The NMDA receptor current, by providing a sustained and regenerative current injection, was critical for activating the ITS, which was not self-regenerative. Moreover, NMDA receptors determined temporal summation of impulses during repetitive mossy fiber transmission, raising membrane potential into the range required for generating protracted Ca2+ channel-dependent depolarizations. The nature of Ca2+ action potentials was considered further using selective ion channel blockers. N-, L-, and P-type Ca2+ channels generated protracted depolarizations, whereas the ITS and HTS transient phase was generated by putative R-type channels (RITS and RHTS, respectively). RHTS channels had a higher activation threshold and were more resistant to voltage inactivation than RITS channels. At a mature stage, most of the Ca2+-dependent effects depended on the N-type current, which promoted spike repolarization and regulated the Na+-dependent discharge frequency. These observations relate Ca2+ channel types with specific neuronal excitable properties and developmental states in situ. Synaptic NMDA receptor-dependent activation of Ca2+ action potentials provides a sophisticated mechanism for Ca2+ signaling, which might be involved in granule cell development and plasticity.

L'autrice, tramite la ricostruzione dei percorsi individuali di alcuni garibaldini veneti (specie nel periodo compreso tra il 1859 e il 1866), si propone di esaminare il complesso quadro motivazionale che sta alla base della scelta di indossare la camicia rossa. Nel seguire tali percorsi, l'esame di scritture autobiografiche quali diari, memorie e lettere consente di cogliere non solo esempi di forte interiorizzazione del discorso nazional-patriottico, ma anche casi in cui la scelta dell'impegno per la patria si collega al desiderio di fuggire dalla miseria, di migliorare le proprie condizioni di vita o di fare carriera militare; non mancano inoltre ragioni di carattere psicologicoesistenziale, come lo spirito d'avventura, l'incoscienza giovanile, l'irrequietezza, la noia, il facile entusiasmo etc., che si vanno ad affiancare ad altre piů profonde, legate a particolari situazioni familiari e alla presenza o assenza della figura paterna. Seppur esaminate separatamente, l'autrice ha cercato di evidenziare lo stretto intreccio esistente tra queste diverse motivazioni, sottolineando la complessitÀ dell'argomento e tenendo conto dei diversi orientamenti espressi a riguardo dalla storiografia risorgimentale.

Demand for mineral resources is increasing, necessitating exploitation of lower grade and more heterogeneous orebodies. The high variability inherent in such orebodies leads to an increase in the cost, complexity and environmental footprint associated with mining and mineral processing. Enhanced knowledge of orebody characteristics is thus vital for mining companies to optimize profitability. We present a pilot study to investigate prediction of geometallurgical variables from drill sensor data. A comparison is made of the performance of multilayer perceptron (MLP) and multiple linear regression models (MLR) for predicting a geometallurgical variable. This comparison is based on simulated data that are physically realistic, having been derived from models fitted to the one available drill core. The comparison is made in terms of the mean and standard deviation (over repeated samples from the population) of the mean absolute error, root mean square error, and coefficient of determination. The best performing model depends on the form of the response variable and the sample size. The standard deviation of performance measures tends to be higher for the MLP, and MLR appears to offer a more consistent performance for the test cases considered. References R. M. Balabin and S. V. Smirnov. Interpolation and extrapolation problems of multivariate regression in analytical chemistry: Benchmarking the robustness on near-infrared (NIR) spectroscopy data”. Analyst 137.7 (2012), pp. 1604–1610. doi: 10.1039/c2an15972d C. M. Bishop. Pattern recognition and machine learning. Springer, 2006. url: https://link.springer.com/book/9780387310732 J. B. Boisvert, M. E. Rossi, K. Ehrig, and C. V. Deutsch. Geometallurgical modeling at Olympic dam mine, South Australia”. Math. Geosci. 45 (2013), pp. 901–925. doi: 10.1007/s11004-013-9462-5 T. Bollerslev. Generalized autoregressive conditional heteroskedasticity”. J. Economet. 31.3 (1986), pp. 307–327. doi: 10.1016/0304-4076(86)90063-1 C. Both and R. Dimitrakopoulos. Applied machine learning for geometallurgical throughput prediction—A case study using production data at the Tropicana Gold Mining Complex”. Minerals 11.11 (2021), p. 1257. doi: 10.3390/min11111257 J. Chen and G. Li. Tsallis wavelet entropy and its application in power signal analysis”. Entropy 16.6 (2014), pp. 3009–3025. doi: 10.3390/e16063009 S. Coward, J. Vann, S. Dunham, and M. Stewart. The primary-response framework for geometallurgical variables”. Seventh international mining geology conference. 2009, pp. 109–113. https://www.ausimm.com/publications/conference->url: https://www.ausimm.com/publications/conference- proceedings/seventh-international-mining-geology- conference-2009/the-primary-response-framework-for- geometallurgical-variables/ A. C. Davis and N. B. Christensen. Derivative analysis for layer selection of geophysical borehole logs”. Comput. Geosci. 60 (2013), pp. 34–40. doi: 10.1016/j.cageo.2013.06.015 C. Dritsaki. An empirical evaluation in GARCH volatility modeling: Evidence from the Stockholm stock exchange”. J. Math. Fin. 7.2 (2017), pp. 366–390. doi: 10.4236/jmf.2017.72020 R. F. Engle and T. Bollerslev. Modelling the persistence of conditional variances”. Econ. Rev. 5.1 (1986), pp. 1–50. doi: 10.1080/07474938608800095 A. S. Hadi and R. F. Ling. Some cautionary notes on the use of principal components regression”. Am. Statistician 52.4 (1998), pp. 15–19. doi: 10.2307/2685559 J. Hunt, T. Kojovic, and R. Berry. Estimating comminution indices from ore mineralogy, chemistry and drill core logging”. The Second AusIMM International Geometallurgy Conference (GeoMet) 2013. 2013, pp. 173–176. http://ecite.utas.edu.au/89773>url: http://ecite.utas.edu.au/89773 on p. C210). R. Hyndman, Y. Kang, P. Montero-Manso, T. Talagala, E. Wang, Y. Yang, M. O’Hara-Wild, S. Ben Taieb, H. Cao, D. K. Lake, N. Laptev, and J. R. Moorman. tsfeatures: Time series feature extraction. R package version 1.0.2. 2020. https://CRAN.R-project.org/package=tsfeatures>url: https://CRAN.R-project.org/package=tsfeatures on p. C222). C. L. Johnson, D. A. Browning, and N. E. Pendock. Hyperspectral imaging applications to geometallurgy: Utilizing blast hole mineralogy to predict Au-Cu recovery and throughput at the Phoenix mine, Nevada”. Econ. Geol. 114.8 (2019), pp. 1481–1494. doi: 10.5382/econgeo.4684 E. B. Martin and A. J. Morris. An overview of multivariate statistical process control in continuous and batch process performance monitoring”. Trans. Inst. Meas. Control 18.1 (1996), pp. 51–60. doi: 10.1177/014233129601800107 E. Sepulveda, P. A. Dowd, C. Xu, and E. Addo. Multivariate modelling of geometallurgical variables by projection pursuit”. Math. Geosci. 49.1 (2017), pp. 121–143. doi: 10.1007/s11004-016-9660-z S. J. Webb, G. R. J. Cooper, and L. D. Ashwal. Wavelet and statistical investigation of density and susceptibility data from the Bellevue drill core and Moordkopje borehole, Bushveld Complex, South Africa”. SEG Technical Program Expanded Abstracts 2008. Society of Exploration Geophysicists, 2008, pp. 1167–1171. doi: 10.1190/1.3059129 R. Zuo. Identifying geochemical anomalies associated with Cu and Pb–Zn skarn mineralization using principal component analysis and spectrum–area fractal modeling in the Gangdese Belt, Tibet (China)”. J. Geochem. Explor. 111.1-2 (2011), pp. 13–22. doi: 10.1016/J.GEXPLO.2011.06.012

Nell’ottobre del 1921 a Milano nacque la Scuola Superiore di Arte Cristiana Beato Angelico. Responsabili dell’iniziativa: don Giuseppe Polvara, l’architetto Angelo Banfi, il pittore Vanni Rossi, affiancati dallo scultore Franco Lombardi, dai sacerdoti Adriano e Domenico Bernareggi, dall’ingegner Giovanni Dedè, dal professor Giovanni Mamone e dall’avvocato Carlo Antonio Vianello. Gli allievi del primo anno scolastico furono nove, due dei quali (gli architetti don Giacomo Bettoli e Fortunato De Angeli) destinati a restare per lunghi anni nella Scuola come docenti: così avvenne anche col pittore Ernesto Bergagna, iscrittosi l’anno seguente. A partire da quell’avvenimento il contesto italiano dell’arte sacra poté contare su un elemento di indiscutibile novità, destinato nel giro di pochi anni a una rapida, diffusa e pervicace affermazione nella Penisola. La fondazione della Scuola Beato Angelico mise un punto fermo nell’annoso dibattito sul generale declino dell’arte sacra che andava in scena da lungo tempo in Italia così come nei principali Paesi europei. La formula ideata da don Polvara metteva a sistema le proprie esperienze personali, artistiche e professionali con la conoscenza del contesto internazionale, di alcuni modelli esemplari e il confronto con gruppi e singole figure (artisti, critici, uomini di Chiesa) animate dal comune desiderio di contribuire alla rinascita dell’arte sacra. A cento anni dalla sua nascita – e a settanta dalla scomparsa del suo fondatore – la Scuola Beato Angelico (coi laboratori di Architettura, Cesello, Ricamo, Pittura e Restauro) prosegue tuttora nel compito di servire la Chiesa attraverso la realizzazione di arredi e paramenti sacri contraddistinti da una particolare cura dell’aspetto artistico e liturgico, oggetto di ripetute attestazioni di merito e riconoscimenti in ambito ecclesiastico. Ciò che invece finora manca all’appello è un organico tentativo di ricostruzione delle vicende storiche che hanno segnato la genesi e gli sviluppi di questa singolare realtà artistica e religiosa. Scopo di questa tesi è quindi la restituzione di un profilo il più possibile dettagliato e ragionato della storia della Scuola Beato Angelico, tale da riportare questa vicenda al centro di una situazione storica e di un contesto culturale complesso, attraverso una prospettiva di lavoro originale condotta sul filo delle puntualizzazioni e delle riscoperte. Stante il carattere “pionieristico” di questa ricerca, la vastità dei materiali e delle fonti a disposizione e la conseguente necessità di assegnare un taglio cronologico riconoscibile al lavoro si è optato per circoscrivere l’indagine ai decenni compresi tra il 1921 e il 1950, ovvero tra la fondazione della Beato Angelico e la scomparsa di Giuseppe Polvara. Come si vedrà, il termine iniziale viene in un certo senso anticipato dall’esigenza di tratteggiare al meglio gli antefatti e il contesto da cui trae origine la Scuola (tra la fine del XIX e i primi decenni del XX secolo). L’anno assunto a conclusione della ricerca, invece, è parso una scelta quasi obbligata, coincidente col primo avvicendamento alla direzione della Beato Angelico oltre che dalla volontà di escludere dal discorso quanto andò avviandosi negli anni Cinquanta e Sessanta, ossia una nuova e diversa stagione nel campo dell’arte sacra (destinata, tra l’altro, a passare attraverso lo snodo rappresentato dal Concilio Vaticano II e dall’azione di S. Paolo VI), peraltro assai indagata dagli studi storico-artistici. Ciò che ha reso possibile la stesura di questa tesi è il fatto che essa si appoggi, in buona parte, su materiali archivistici inediti o, quantomeno, mai esaminati prima d’ora in modo strutturato. L’accesso ai materiali d’archivio più storicizzati e la loro consultazione (grazie alla disponibilità dimostrata dalla direzione della Scuola Beato Angelico) hanno condizionato in modo determinante la trattazione degli argomenti, la ricostruzione dei quali , in alcuni casi, è sostenuta esclusivamente dai documenti rinvenuti. La nascita della Scuola Beato Angelico non fu un accadimento isolato nel panorama della produzione artistica europea del tempo né un episodio estraneo a quanto, contemporaneamente, si andava dibattendo nel mondo ecclesiastico. La Scuola di Polvara nacque in un’epoca contrassegnata da grande fermento ecclesiale: si pensi agli Ateliers d’Art Sacré fondati da Maurice Denis e George Desvallières a Parigi nel 1919, solo due anni prima della Scuola milanese, i cui aderenti – tutti laici – professavano una religiosità intensa e devota. Ma, soprattutto, il modello determinante e più conosciuto da Polvara fu la Scuola di Beuron (Beuroner Kunstschule), nata nell’omonima abazia benedettina tedesca nell’ultimo quarto del XIX secolo a opera di padre Desiderius Lenz e sul cui esempio ben presto sorsero atelier specializzati nella produzione di arte sacra (arredi e paramenti a uso liturgico) in molte comunità benedettine dell’Europa centrale. L’affinità di Polvara con la spiritualità benedettina è un elemento-chiave della Scuola da lui fondata: dalla regola dell’ora et labora derivò infatti il concetto (analogo) di “preghiera rappresentata” (orando labora). L’organizzazione stessa della Scuola, impostata come in un’ideale bottega medievale dove maestri, apprendisti e allievi collaborano e convivono, riprende lo stile di vita monastico dei cenobi benedettini. Proprio al fine di conservare il più possibile il carattere della bottega medievale, il numero degli allievi ammessi alla Scuola non fu mai troppo elevato, così da mantenere un adeguato ed efficace rapporto numerico tra i discepoli e i maestri. Ancora, da Beuron la Beato Angelico trasse la particolare e inconfondibile forma grafica della lettera “e”, riconoscibile nelle numerose e lunghe epigrafi presenti in tante sue opere. Ultimo elemento in comune tra la Scuola milanese e quella tedesca – ma che si può imputare alla più generale fascinazione per l’epoca medievale – è l’unità di intenti che deve animare tutte le maestranze impegnate a creare un’opera collettiva e anonima ad maiorem Dei gloriam, dove il contributo del singolo autore rimane volutamente nascosto in favore del nome della Scuola. Ciò che differenzia, tuttora, la Scuola da analoghi centri di produzione di arte sacra è il fatto che essa poggi le fondamenta su una congregazione religiosa, la Famiglia Beato Angelico, un’idea a lungo coltivata da Polvara e approvata ufficialmente dall’autorità diocesana fra gli anni Trenta e Quaranta. Dalla comune vocazione alla creazione artistica sacra (“missione sacerdotale” dell’artista) discendono la pratica della vita comunitaria, la partecipazione ai sacramenti e ai diversi momenti quotidiani di preghiera da parte di maestri sacerdoti, confratelli e consorelle artisti, apprendisti, allievi e allieve. L’indirizzo spirituale tracciato dal fondatore per la sua Famiglia agisce ancora oggi a garanzia di una strenua fedeltà nella continuità di un progetto artistico e liturgico unico, messo in pratica da una comunità di uomini e donne legate fra loro dai canonici voti di povertà, castità e obbedienza ma soprattutto da un comune e più alto intento. Appunto per assicurare una prospettiva di sopravvivenza e futuro sviluppo della sua creatura, Polvara ebbe sempre chiara la necessità di mantenere unito l’aspetto della formazione (e quindi la didattica nei confronti degli allievi, adolescenti e giovani) con quello della produzione (spettante all’opera di collaborazione fra maestri, apprendisti e allievi). Dal punto di vista operativo le discipline artistiche, praticate nei vari laboratori in cui si articola la Scuola, concorrono, senza alcuna eccezione e nella citata forma anonima e collettiva, a creare un prodotto artistico organico e unitario, una “opera d’arte totale” che deve rispondere all’indirizzo dato dal maestro architetto (lo stesso Polvara), cui spettano devozione, rispetto e obbedienza. Alla progettazione architettonica viene dunque assegnata grande importanza e ciò comporta che le opere meglio rappresentative della Scuola Beato Angelico siano quegli edifici sacri interamente realizzati con l’intervento dei suoi laboratori per tutte o quasi le decorazioni, gli arredi, le suppellettili e i paramenti (come le chiese milanesi di S. Maria Beltrade, S. Vito al Giambellino, SS. MM. Nabore e Felice, o la chiesa di S. Eusebio ad Agrate Brianza e la cappella dell’Istituto religioso delle figlie di S. Eusebio a Vercelli). Quanto ai linguaggi espressivi impiegati dalla Scuola (il cosiddetto “stile”) si evidenziano la preferenza per il moderno razionalismo architettonico – un tema di stringente attualità, cui Polvara non mancò di dare il suo personale contributo teorico e pratico – e quella per il divisionismo in pittura, debitrice dell’antica ammirazione per l’opera di Gaetano Previati. Dall’interazione di queste due forme si origina un riconoscibile linguaggio, moderno e spirituale al tempo stesso, verificabile negli edifici come nelle singole opere, frutto di una profonda sensibilità che combina il ponderato recupero di alcune forme del passato (ad esempio l’iconografia paleocristiana reimpiegata nei motivi decorativi dei paramenti o nella foggia di alcuni manufatti, dal calice al tabernacolo, alla pianeta-casula) con lo slancio per uno stile moderno e funzionale adeguato ai tempi ma rispettoso della tradizione.
In October 1921, the Beato Angelico Higher School of Christian Art was born in Milan. Responsible for the initiative: Don Giuseppe Polvara, the architect Angelo Banfi, the painter Vanni Rossi, flanked by the sculptor Franco Lombardi, by the priests Adriano and Domenico Bernareggi, by the engineer Giovanni Dedè, by professor Giovanni Mamone and by the lawyer Carlo Antonio Vianello . There were nine pupils in the first school year, two of whom (the architects Don Giacomo Bettoli and Fortunato De Angeli) destined to remain in the School for many years as teachers: this also happened with the painter Ernesto Bergagna, who enrolled the following year. Starting from that event, the Italian context of sacred art was able to count on an element of indisputable novelty, destined within a few years to a rapid, widespread and stubborn affirmation in the Peninsula. The foundation of the Beato Angelico School put a stop to the age-old debate on the general decline of sacred art that had been staged for a long time in Italy as well as in major European countries. The formula conceived by Don Polvara put his personal, artistic and professional experiences into a system with the knowledge of the international context, some exemplary models and the comparison with groups and individual figures (artists, critics, men of the Church) animated by the common desire to contribute to the rebirth of sacred art. One hundred years after its birth - and seventy after the death of its founder - the Beato Angelico School (with the workshops of Architecture, Cesello, Embroidery, Painting and Restoration) still continues in the task of serving the Church through the creation of distinctive sacred furnishings and vestments. from a particular care of the artistic and liturgical aspect, object of repeated attestations of merit and acknowledgments in the ecclesiastical sphere. What is missing from the appeal so far is an organic attempt to reconstruct the historical events that marked the genesis and developments of this singular artistic and religious reality. The purpose of this thesis is therefore the return of a profile as detailed and reasoned as possible of the history of the Beato Angelico School, such as to bring this story back to the center of a historical situation and a complex cultural context, through an original work perspective conducted on thread of clarifications and rediscoveries. Given the "pioneering" nature of this research, the vastness of the materials and sources available and the consequent need to assign a recognizable chronological cut to the work, it was decided to limit the survey to the decades between 1921 and 1950, or between the foundation of Beato Angelico and the death of Giuseppe Polvara. As will be seen, the initial term is in a certain sense anticipated by the need to better outline the background and context from which the School originates (between the end of the 19th and the first decades of the 20th century). The year assumed at the end of the research, on the other hand, seemed an almost obligatory choice, coinciding with the first change in the direction of Beato Angelico as well as the desire to exclude from the discussion what started in the 1950s and 1960s, that is a new and different season in the field of sacred art (destined, among other things, to pass through the junction represented by the Second Vatican Council and by the action of St. Paul VI), which is however much investigated by historical-artistic studies. What made the drafting of this thesis possible is the fact that it relies, in large part, on unpublished archival materials or, at least, never examined before in a structured way. Access to the most historicized archive materials and their consultation (thanks to the availability shown by the direction of the Beato Angelico School) have decisively conditioned the discussion of the topics, the reconstruction of which, in some cases, is supported exclusively by documents found. The birth of the Beato Angelico School was not an isolated event in the panorama of European artistic production of the time nor an episode unrelated to what was being debated in the ecclesiastical world at the same time. The Polvara School was born in an era marked by great ecclesial ferment: think of the Ateliers d'Art Sacré founded by Maurice Denis and George Desvallières in Paris in 1919, only two years before the Milanese School, whose adherents - all lay people - they professed an intense and devoted religiosity. But, above all, the decisive and best known model by Polvara was the Beuron School (Beuroner Kunstschule), born in the homonymous German Benedictine abbey in the last quarter of the nineteenth century by father Desiderius Lenz and on whose example workshops specialized in the production of sacred art (furnishings and vestments for liturgical use) in many Benedictine communities in central Europe. Polvara's affinity with Benedictine spirituality is a key element of the School he founded: in fact, the (analogous) concept of "represented prayer" (orando labora) derived from the rule of the ora et labora. The very organization of the School, set up as in an ideal medieval workshop where teachers, apprentices and pupils collaborate and coexist, takes up the monastic lifestyle of the Benedictine monasteries. Precisely in order to preserve the character of the medieval workshop as much as possible, the number of students admitted to the School was never too high, so as to maintain an adequate and effective numerical ratio between disciples and masters. Again, from Beuron Fra Angelico drew the particular and unmistakable graphic form of the letter "e", recognizable in the numerous and long epigraphs present in many of his works. The last element in common between the Milanese and the German schools - but which can be attributed to the more general fascination for the medieval era - is the unity of purpose that must animate all the workers involved in creating a collective and anonymous work ad maiorem. Dei gloriam, where the contribution of the single author remains deliberately hidden in favor of the name of the School. What still differentiates the School from similar centers of production of sacred art is the fact that it rests its foundations on a religious congregation, the Beato Angelico Family, an idea long cultivated by Polvara and officially approved by the diocesan authority between the thirties and forties. From the common vocation to sacred artistic creation (the artist's "priestly mission") descend the practice of community life, the participation in the sacraments and the various daily moments of prayer by master priests, brothers and sisters artists, apprentices, pupils and pupils . The spiritual direction traced by the founder for his family still acts today as a guarantee of a strenuous fidelity in the continuity of a unique artistic and liturgical project, put into practice by a community of men and women linked together by the canonical vows of poverty, chastity. and obedience but above all from a common and higher intent. Precisely to ensure a prospect of survival and future development of his creature, Polvara always had a clear need to keep the training aspect (and therefore the teaching for students, adolescents and young people) united with that of production (due to the work of collaboration between teachers, apprentices and students). From an operational point of view, the artistic disciplines, practiced in the various laboratories in which the School is divided, contribute, without any exception and in the aforementioned anonymous and collective form, to create an organic and unitary artistic product, a "total work of art" which must respond to the address given by the master architect (Polvara himself), to whom devotion, respect and obedience are due. The architectural design is therefore assigned great importance and this means that the best representative works of the Beato Angelico School are those sacred buildings entirely made with the intervention of its laboratories for all or almost all the decorations, furnishings, furnishings and Milanese churches of S. Maria Beltrade, S. Vito al Giambellino, S. MM. Nabore and Felice, or the church of S. Eusebio in Agrate Brianza and the chapel of the religious institute of the daughters of S. Eusebio in Vercelli). As for the expressive languages used by the School (the so-called "style"), the preference for modern architectural rationalism is highlighted - a topic of stringent topicality, to which Polvara did not fail to give his personal theoretical and practical contribution - and that for Divisionism in painting, indebted to the ancient admiration for the work of Gaetano Previati. The interaction of these two forms gives rise to a recognizable language, modern and spiritual at the same time, verifiable in the buildings as in the individual works, the result of a profound sensitivity that combines the thoughtful recovery of some forms of the past (for example early Christian iconography reused in the decorative motifs of the vestments or in the shape of some artifacts, from the chalice to the tabernacle, to the chasuble-chasuble) with the impetus for a modern and functional style appropriate to the times but respectful of tradition.