Search results for "object"

A NOTE ON THE CATEGORICAL NOTIONS OF NORMAL SUBOBJECT AND OF EQUIVALENCE CLASS

2021

In a non-pointed category E, a subobject which is normal to an equivalence relation is not necessarily an equivalence class. We elaborate this categorical distinction, with a special attention to the Mal'tsev context. Moreover, we introduce the notion of fibrant equipment, and we use it to establish some conditions ensuring the uniqueness of an equivalence relation to which a given subobject is normal, and to give a description of such a relation.

Mathematics and Music: a paradigmatic pair for basic learning

2012

The aim of the trial path described in this article is to highlight the possibility to develop intuition, analysis and synthesis abilities, which are typical of the logical - deductive mathematical thought, in primary school children (2nd class), through a significant approach to musical education, meant as systematic analysis of the sound parameters, which characterize and qualify its language. The Vygotskijan theoretical framework, which leads and interprets the didactic engineering proposed in class, emphasizes how the Mathematics - Music pair has promoted the changeover among different semiotic registers (Duval 2002), referred to Natural, iconographic, musical, geometric and pre - algeb…

Family Business Advising, Strategic Work and Unfolding Spaces

2019

The purpose of this paper is to explore the ways in which the process of advising, as well as the family firm-professional advisor relationship, can unfold over time and perform strategic work. To achieve this aim, we rely upon the experience of a family firm and its evolving relationship with an external advisor in the management accounting field. Over a period of 15 years, strategy work was performed through (and shaped by) unfolding ‘strategy spaces’ within which the advisor made use of multiple material, spatial and discursive resources. By interpreting the empirical evidence with theoretical insights from the strategy-as-practice literature, as well as from organization studies on spac…

Applying the Goal Setting Practice in the Dynamic Balance Scorecard Learning and Growth Perspective

2010

EVA(®) vs. ROE as strategic corporate goals. A microeconomic approach

2018

International audience

Collisionless shock heating of heavy ions in SN 1987A

2019

Astrophysical shocks at all scales, from those in the heliosphere up to the cosmological shock waves, are typically "collisionless", because the thickness of their jump region is much shorter than the collisional mean free path. Across these jumps, electrons, protons, and ions are expected to be heated at different temperatures. Supernova remnants (SNRs) are ideal targets to study collisionless processes because of their bright post-shock emission and fast shocks. Although optical observations of Balmer-dominated shocks in young SNRs showed that the post-shock proton temperature is higher than the electron temperature, the actual dependence of the post-shock temperature on the particle mass…

Indications of a Si-rich bilateral jet of ejecta in the Vela SNR observed with XMM-Newton

2017

Context. The Vela supernova remnant displays several ejecta, which are fragment-like features protruding beyond the front of its primary blast shock wave. They appear to be "shrapnel", bowshock-shaped relics of the supernova explosion. One of these pieces of shrapnel (A), located in the northeastern edge of the remnant, is peculiar because its X-ray spectrum exhibits a high Si abundance, in contrast to the other observed ejecta fragments, which show enhanced O, Ne, and Mg abundances. Aims. In this Letter we present the analysis of another ejecta fragment located opposite to shrapnel A with respect to the center of the shell, in the southwestern boundary of the remnant, named shrapnel G. We …

X-ray Emission from Protostellar Jets

2008

The nearest X-ray emitting protostellar jet (HH 154) observed with Hubble

2008

Context. The jet coming from the YSO binary L1551 IRS5 is the closest astrophysical jet known. It is therefore a unique laboratory for studies of outflow mechanisms and of the shocks occurring when expanding material hits the ambient medium as well as of how the related processes influence the star- (and planet-) forming process. Aims. The optical data are related to other data covering the spectrum from the optical band to X-rays with goal of understanding the energetics of low-mass star jets, in general, and of this jet in particular. We study the time evolution of the jet, by measuring the proper motions of knots as they progress outwards from the originating source. Methods. The nebulos…

Laboratory evidence for asymmetric accretion structure upon slanted matter impact in young stars

2020

Aims. Investigating the process of matter accretion onto forming stars through scaled experiments in the laboratory is important in order to better understand star and planetary system formation and evolution. Such experiments can indeed complement observations by providing access to the processes with spatial and temporal resolution. A previous investigation revealed the existence of a two-component stream: a hot shell surrounding a cooler inner stream. The shell was formed by matter laterally ejected upon impact and refocused by the local magnetic field. That laboratory investigation was limited to normal incidence impacts. However, in young stellar objects, the complex structure of magne…