1,721,050 research outputs found
Intramolecular reorganization energies and Franck–Condon integrals for ET from pheophytin to quinone in bacterial photosynthetic reaction centers
No full textPerformance evaluation of a bufferless optical packet switch with limited-range wavelength converters
No full textIn this letter, we introduce an analytical model which enables us to evaluate the performance of a bufferless optical packet switch equipped with limited-range wavelength converters (LRWCs). The model is applied in order to calculate the packet-loss probability as a function of the conversion range, when an optimum scheduling algorithm is adopted. The analytical results show that a switch equipped with LRWCs with a small range can match the performance of an architecture using full-range wavelength converters
Role of intramolecular vibrations in long range electron transfer between pheophytin and ubiquinone in bacterial photosynthetic reaction centers
No full textAbstractThe dynamics of the elementary electron transfer step between pheophytin and primary ubiquinone in bacterial photosynthetic reaction centers is investigated by using a discrete state approach, including only the intramolecular normal modes of vibration of the two redox partners. The whole set of normal coordinates of the acceptor and donor groups have been employed in the computations of the Hamiltonian matrix, to reliably account both for shifts and mixing of the normal coordinates, and for changes in vibrational frequencies upon ET. It is shown that intramolecular modes provide not only a discrete set of states more strongly coupled to the initial state but also a quasicontinuum of weakly coupled states, which account for the spreading of the wave packet after ET. The computed transition probabilities are sufficiently high for asserting that electron transfer from bacteriopheophytin to the primary quinone can occur via tunneling solely promoted by intramolecular modes; the transition times, computed for different values of the electronic energy difference and coupling term, are of the same order of magnitude (102 ps) of the observed one
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Stand up for your copyright: la prospettiva dell'autore
Full text linkPresentation about copyright and scentific authors. Presentation held at the workshop : "Dopo Berlin 3: politiche di accesso aperto alla letteratura scientifica" (University of Pisa, 16 febbraio 2006)
The Foundations of Hegemony in Egypt Before and After the 2011 Revolution: Disgregazione, Organic Intellectuals, and the ‘Southern Question’ as Method.
No full textDuring the decade before Egypt’s 2011 revolution, independent pro-
democracy human rights activists played an important role in the
mobilization that prepared the ground for Mubarak’s ouster. Hailed
as pioneers of the revolution during its heyday, once counter-
revolutionary forces from the old regime gained the upper hand,
those same Independent Civic Activists’ (ICAs) were faulted for not
having a sufficiently revolutionary ideology or program to ‘take the
state’ (Bayat 2017), or their defeat was said to have been caused
by their weakness compared to the coercive capacity of the Army or the logistical infrastructure of the Muslim Brotherhood (Bellin
2012). Yet if ICAs slowly eroded Egypt’s authoritarian regime before
2011, it is necessary to explain why they were unable to do so after
Mubarak’s removal. Likewise, if the coercive imbalance between
ICAs and the regime or the Brotherhood was overwhelming, it is
difficult to explain ICAs’ role before the Revolution. More generally,
if ICAs’ agency – with all its limitations – existed and was effective
before the Revolution, it must be retrieved in the analysis of events
after Mubarak was ousted. This chapter engages with Gramsci’s
original writings and with Italophone scholarship on Gramsci and
draws together our previous work on ICAs before and after the
Revolution with the aim of presenting an original elaboration of
disgregazione in Gramsci’s Prison Notebooks and his Notes on the
Southern Question that might help explain the Revolution’s ‘defeat’
while properly accounting for ICAs’ agency. Both empirical and
theoretical reflections contribute to the elaboration of a new wave
of ‘Gramscian’ scholarship in Middle East Studies
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