Search results for "Rossi"

Intersystem crossing in Fe(II) coordination compounds

1994

Fe(II) spin-crossover systems can be quantitatively converted from the low-spin (LS) to the high-spin (HS) state well below the thermal transition temperature by irradiating either into the metal-ligand charge transfer or d-d absorption bands, and even in low-spin systems a transient population of the HS state can be achieved. This fact can be made use of to determine HS → LS relaxation rate constants for a wide variety of Fe(II) spin-crossover and low-spin systems. The HS → LS relaxation shows strong deviations from an Arrhenius behaviour, with nearly temperature-independent tunnelling below ∼70 K and a thermally activated process above ∼100 K. The range of more than 12 orders of magnitude…

Irradiation induced Germanium Lone Pair Centers in Ge-doped Sol-gel SiO2: luminescence lifetime and temperature dependence

2010

We studied the temperature dependence of the emission profile and of the lifetime, measured at 4.3 eV, related to the germanium lone pair centers (GLPC) induced by gamma ray at 5 MGy in a Ge-doped silica sample and in an analogous sample irradiated at 10 MGy, in which by a successive thermal treatment up to 415 °C the induced GLPC has been modified (named residual GLPC in the following). The measurements were recorded in the temperature range 10-300 K using an excitation of ∼5.2 eV. The data show that the energy level scheme of the induced and the residual GLPC is very similar to that of the native defects generated during the synthesis, and the intersystem crossing process (ISC) of the ind…

Long-range interactions and the sign of natural amplitudes in two-electron systems

2013

In singlet two-electron systems the natural occupation numbers of the one-particle reduced density matrix are given as squares of the natural amplitudes which are defined as the expansion coefficients of the two-electron wave function in a natural orbital basis. In this work we relate the sign of the natural amplitudes to the nature of the two-body interaction. We show that long-range Coulomb-type interactions are responsible for the appearance of positive amplitudes and give both analytical and numerical examples that illustrate how the long-distance structure of the wave function affects these amplitudes. We further demonstrate that the amplitudes show an avoided crossing behavior as func…

Level-crossing rate and average duration of fades of non-stationary multipath fading channels

2017

The level-crossing rate (LCR) and average duration of fades (ADF) are important statistical quantities describing the fading behaviour of mobile radio channels. To date, these quantities have only been analysed under the assumption that the mobile radio channel is wide-sense stationary, which is generally not the case in practice. In this paper, we propose a concept for the analysis of the LCR and ADF of non-stationary channels. Rice's standard formula for the derivation of the LCR of wide-sense stationary processes is extended to a more general formula enabling the computation of the instantaneous LCR of non-stationary processes. The application of the new concept results in closed-form ex…

Intervista a Bernardo Rossi Doria

2007

Crossing Borders. Concepts and Practices for a New Planetary Dimension

2020

The essay takes into account some categories and practices of colonial relations by considering both domination and subjectification processes and handles the concept of border and the complex dynamics of crossing, mobility, diaspora, and hybridization. The critical analysis of the hierarchical order of the world highlights the ways in which the relations between non-homogeneous elements produce conflict and assimilation practices, but also contaminations and inclusion. By assuming the "colonial" as a precarious concept, the essay stresses the discursive aspects of dominion but also the government, counter-conducts, and resistances, without forecloses the persistence of the epistemological …

Città della prossimità aumentata

2021

La sfida per le città aumentate antisindemiche sarà quella di recuperare il loro naturale policentrismo, la diversità dei loro quartieri e borgate che, smettendo di essere fragili periferie senza diritti, tornino ad essere luoghi di vite e non solo di abitazioni, colmando il divario educativo, lavorativo, sanitario, culturale, digitale, dotandosi di micro-presìdi di salute pubblica e di comunità energetiche autosufficienti. Immagino città fondate su una nuova prossemica che riduca la loro forsennata mobilità centripeta, garantendo la risposta a molti bisogni entro un raggio di 15 minuti a piedi (lo stanno già facendo Parigi, Barcellona, Milano, Bologna). Voglio proporre qui una “città della…

The role of native flower visitors in pollinating Opuntia ficus-indica (L.) Mill., naturalized in Sicily

2011

Abstract The role of insects in pollination and consequently in fruit set and quality was assessed in two commercial orchards of the cactus pear, Opuntia ficus-indica (L.) Mill., in Agrigento Province, Sicily. In 1997, insects visiting flowers were sampled during May–June (the first bloom) and July (the second bloom, induced by the “scozzolatura” practise). More than 50 insect species belonging to 10 orders were collected in May–June, while only five species of Hymenoptera Apoidea were collected in July. The quality of fruits arising from the second bloom showed that Hymenoptera alone were able to guarantee effective pollination. To verify the role of insects in pollination in 1996 (during …

'Sinking Hopeful Roots into Difficult Soil': Caryl Phillips' Crossing the River.

1998

This article proposes a reading of Caryl Phillips Booker-shortlisted novel Crossing the River as an exemplary text of the African Diaspora.

Three simultaneous dissolution profiles on a solid pharmaceutical formulation by a FIA manifold provided with a single spectrophotometric detector.

2003

This article deals with the simultaneous determination of three dissolution profiles in the same pharmaceutical formulation. The officially proposed procedure from the pharmacopoeias is adapted to the FIA methodology to obtain the officially recommended profile or "global profile", and two "individual" profiles, corresponding to dissolution rate of two different active principles present in the formulation; both drugs have overlapped UV-vis spectra. The simultaneous determination of several profiles is based on the derivative spectra and the zero crossing mathematical procedure for the "individual" profiles of an active principle; the "global" profile of the formulation is obtained from the…