The on-axis view of GRB 170817A

The peculiar short gamma-ray burst GRB 170817A has been firmly associated to the gravitational wave event GW170817, which has been unaninmously interpreted as due to the coalescence of a double neutron star binary. The unprecedented behaviour of the non-thermal afterglow led to a debate about its nature, which was eventually settled by high-resolution VLBI observations, which strongly support the off-axis structured jet scenario. Using information on the jet structure derived from multi-wavelength fitting of the afterglow emission and of the apparent VLBI image centroid motion, we compute the appearance of a GRB 170817A-like jet as seen by an on-axis observer and we compare it to the previously observed population of SGRB afterglows and prompt emission events. We find that the intrinsic properties of the GRB 170817A jet are representative of a typical event in the SGRB population, hinting at a quasi-universal jet structure. The diversity in the SGRB afterglow population could therefore be ascribed in large part to extrinsic (redshift, density of the surrounding medium, viewing angle) rather than intrinsic properties. Although more uncertain, the comparison can be extended to the prompt emission properties, leading to similar conclusions.Comment: 9 pages, 3 figures, submitted to A&A. Comments and suggestions are welcom

Letteratura ed esperienza magistrale femminile nell\u2019Italia di fine Ottocento. La costruzione di una difficile identit\ue0 in \uabScuola Normale Femminile\ubb di Matilde Serao (1885)

Agli inizi del 1885 Matilde Serao pubblicava per la prima volta, a puntate, sulla \uabNuova Antologia\ubb, la novella Scuola Normale Femminile, destinata a inaugurare un filone letterario \u2013 quello dei racconti e romanzi dedicati alle vicende di maestre e maestri e alle vicissitudini della scuola e dell\u2019istruzione pubblica nell\u2019Italia postunitaria \u2013 che avrebbe registrato una notevole fortuna nell\u2019ultimo quindicennio del secolo XIX. Attraverso l\u2019esame del racconto, viene attentamente ricostruita la temperie sociale e culturale, come anche la fase storica particolarmente significativa dell\u2019evoluzione della scuola e dell\u2019identit\ue0 magistrale femminile nell'Italia del secondo Ottocento. At the beginning of the year 1885, Matilde Serao first published, in installments in the journal "Nuova Antologia", the short story Scuola Normale Femminile (Normal School for women), which was destined to meet with considerable success in the last fifteen years of the 19th century and consequently to inaugurate a new literary genre - that of novels and tales focused on stories of male and female teachers and on the vicissitudes of school and public education in post-unitary Italy. Through an examination of the stories and the characters, the social and cultural climate is carefully reconstructed along with the historical moment - particularly significant in the historical evolution of schools and the professional identity of women teachers

On Parameterizations of plane rational curves and their syzygies

Let $C$ be a plane rational curve of degree $d$ and $p:\tilde C \rightarrow C$ its normalization. We are interested in the splitting type $(a,b)$ of $C$, where $\mathcal{O}_{\mathbb{P}^1}(-a-d)\oplus \mathcal{O}_{\mathbb{P}^1}(-b-d)$ gives the syzigies of the ideal $(f_0,f_1,f_2)\subset K[s,t]$, and $(f_0,f_1,f_2)$ is a parameterization of $C$. We want to describe in which cases $(a,b)=(k,d-k)$ ($2k\leq d)$, via a geometric description; namely we show that $(a,b)=(k,d-k)$ if and only if $C$ is the projection of a rational curve on a rational normal surface in $\mathbb{P}^{k+1}$.Comment: 12 Page

The image of Giuseppe Mazzini in history textbooks from italian unification to the end of world war II (1861-1945)

The image of Giuseppe Mazzini and the Mazzinian movement is reconstructed as chronicled in Italian history texts used in public primary and secondary schools, that is to say those textbooks which enjoyed a much wider circulation and therefore contributed far more significantly to the creation of a collective image of the life and work of this figure. Analyzing omissions, as well as censorship and myths, the infinite and surprising metamorphoses for ideological and political purposes that this historical figure has undergone, can be followed and rebuilt through manuals of five historical periods: the first decade following Unification; the period from the early 1870s to the late 1880s; the last decade of the nineteenth century; the Giolitti era; and finally the post-WWI period through the mid-1920s and the years of Fascist totalitarianism. The scholastic texts return to us the trends of the national historiographic point and the different projects designed to build the national identity and shape the civil and political ethic for new generations. At the same time, the history schoolbooks witness the development process of that national pedagogy which, in different post-Unification periods, inspired and nurtured the teaching activity in Italian schools. L'articolo ricostruisce l\u2019immagine di Giuseppe Mazzini e del movimento mazziniano cos\uec come essi venivano raccontati nei manuali di storia in uso nelle scuole pubbliche primarie e secondarie, vale a dire quei libri di testo che conobbero una diffusione molto ampia e, quindi, contribuirono in modo assai significativo alla creazione di un'immagine collettiva della vita e dell\u2019operato di questa figura. Analizzando le omissioni cos\uec come l\u2019opera di censura e di mitizzazione, \ue8 possibile seguire le infinite e sorprendenti metamorfosi, per fini ideologici e politici, che questa figura storica sub\uec, ricostruendole attraverso i manuali di cinque diversi periodi storici: il decennio successivo all\u2019unificazione, il periodo dai primi anni 1870 alla fine del 1880, l'ultimo decennio del XIX secolo, l'et\ue0 giolittiana, e infine il periodo tra il primo dopoguerra, passando per il ventennio e il totalitarismo fascista. I testi scolastici riflettono le tendenze della storiografia nazionale e dei diversi progetti volti a costruire l'identit\ue0 nazionale e a modellare l'etica civile e politica per le nuove generazioni. Allo stesso tempo, i manuali di storia testimoniano il processo di sviluppo della pedagogia nazionale che, nei diversi periodi successivi all\u2019unificazione, ispirarono e nutrirono l'attivit\ue0 didattica nelle scuole italiane

The magnetospheric radius of an inclined rotator in the magnetically threaded disk model

The estimate of the magnetospheric radius in a disk-fed neutron star X-ray binary is a long standing problem in high energy Astrophysics. We review the magnetospheric radius calculations in the so-called magnetically threaded disk model, comparing the simplified approach originally proposed by Ghosh & Lamb (1979) with the revised version proposed by Wang (1987), Wang (1995), and Wang (1997). We show that for a given set of fixed parameters (assuming also a comparable screening factor of the neutron star magnetic field by the currents induced on the disk surface) the revised magnetically threaded disk model predicts a magnetospheric radius that is significantly smaller than that derived from the Ghosh & Lamb (1979) treatment. For a fixed value of the neutron star magnetic field and a wide range of mass accretion rates, the inclusion of a large inclination angle between the neutron star rotation and magnetic field axes ($\chi$$\gtrsim$60 deg) leads to a further decrease of the magnetospheric radius. To illustrate the relevance of these calculations, we consider, as an example, the case of the transitional pulsars. During the so-called "high mode" of their sub-luminous accretion disk state, these sources have shown X-ray pulsations interpreted as due to accretion at an unprecedented low luminosity level compared to other neutron stars in X-ray binaries. In the context of the magnetic threaded disk model, we show that accretion at luminosities of $\sim$10$^{33}$ erg s$^{-1}$ (and thus accretion-driven X-ray pulsations) can be more easily explained when the prescription of the magnetospheric radius provided by Wang (1997) is used. This avoids the need of invoking very strong propeller outflows in the transitional pulsars, as proposed in other literature works.Comment: Accepted for publication in A&

An Exploration of Elementary Teachers\u27 Views of Informal Reading Inventories in Dual Language Bilingual Programs

This study examines how elementary teachers (grades three through five) in dual-language, bilingual programs (Spanish/English) view informal reading inventories (IRIs) to support their students’ reading growth. The research, conducted in an urban district in the Northeastern United States, draws on interviews with 20 teachers in these programs. One significant finding is that although teachers in the sample collected IRIs in the two languages of instruction, they did not examine English and Spanish reading assessment data side by side in order to construct a unified portrait of their students as bilingual readers. This study highlights the finding that IRIs are currently viewed as monolingual assessments rather than as a lens into students’ biliteracy, thus bypassing a powerful way to assist teachers in making instructional decisions in support of students’ bilingual reading development

LA MISSIONE EDUCATIVA DELLA GENERAZIONE DI MEZZO IN TEMPO DI GUERRA: GLI SCRITTI PER LA SCUOLA E PER LA GIOVENTÙ DI LUIGI BERTELLI DEGLI ANNI 1914-1918

L‟idea per cui la Grande Guerra rappresenti uno “spartiacque del mondo contemporaneo” è ormai assodata nella storia tout court (Gibelli, 1991, p. 43). Meno indagate sono, invece, le ripercussioni che il primo conflitto bellico mondiale ebbe sulla scuola del tempo. Una fonte preziosa per esplorare questo terreno è rappresentata certamente dai libri di scuola scritti e pubblicati in questo periodo. Da queste considerazioni muove il contributo che si presenta in questa sede, il quale si concentra sulla produzione per la scuola e la gioventù realizzata da un personaggio illustre della letteratura italiana per ragazzi: Luigi Bertelli. Il noto autore di Gian Burrasca e fondatore del periodico per ragazzi Il Giornalino della Domenica, scrisse numerosi testi destinati alla scuola e alle nuove generazioni durante la prima guerra mondiale. Il presente contributo intende esaminarli, per la prima volta, in modo analitico e puntuale, al fine non solo di restituire un'immagine più articolata del Bertelli autore ed educatore, ma anche di offrire un contributo alla comprensione di quella vera e propria pedagogia della guerra promossa negli anni del primo conflitto mondiale

Inside School Lives: Historiographical Perspectives and Case Studies. Teachers\u2019 Memories Preserved at the Centre for Documentation and Research on the History of Schoolbooks and Children\u2019s Literature

This work focuses on teachers\u2019 memories and intend to dwell on the heuristic potential of this source category, comparing it with the traditional sources of theoretical-regulatory and educational type. After a presentation on the state of art of historical and historical-educational studies on teachers\u2019 memories, it will offer an overview of the different kinds of memories preserved in the centres of documentation and research of historical and educational interest, examining the books and documentary heritage of the Centre for documentation and research on the history of schoolbooks and children\u2019s literature of Macerata University. Finally, through the analysis of a case study, the Memorie (Memoirs) of the teacher and pedagogist Lorenzo Bettini (1855-1917), we will offer an exemplification of a possible integrated use of sources, for a plural reconstruction of teachers\u2019 history

Structural and functional properties of Antarctic fish cytoglobins-1: Cold-reactivity in multi-ligand reactions

While the functions of the recently discovered cytoglobin, ubiquitously expressed in vertebrate tissues, remain uncertain, Antarctic fish provide unparalleled models to study novel protein traits that may arise from cold adaptation. We report here the spectral, ligand-binding and enzymatic properties (peroxynitrite isomerization, nitrite-reductase activity) of cytoglobin-1 from two Antarctic fish, Chaenocephalus aceratus and Dissostichus mawsoni, and present the crystal structure of D. mawsoni cytoglobin-1. The Antarctic cytoglobins-1 display high O2 affinity, scarcely compatible with an O2-supply role, a slow rate constant for nitrite-reductase activity, and do not catalyze peroxynitrite isomerization. Compared with mesophilic orthologues, the cold-adapted cytoglobins favor binding of exogenous ligands to the hexa-coordinated bis-histidyl species, a trait related to their higher rate constant for distal-His/heme-Fe dissociation relative to human cytoglobin. At the light of a remarkable 3D-structure conservation, the observed differences in ligand-binding kinetics may reflect Antarctic fish cytoglobin-1 specific features in the dynamics of the heme distal region and of protein matrix cavities, suggesting adaptation to functional requirements posed by the cold environment. Taken together, the biochemical and biophysical data presented suggest that in Antarctic fish, as in humans, cytoglobin-1 unlikely plays a role in O2 transport, rather it may be involved in processes such as NO detoxification