332 research outputs found
E-readers and the death of the book: or, new media and the myth of the disappearing medium
The recent emergence of e-readers and e-books has b
rought the death of the book to the centre of
current debates on new media. In this article, we a
nalyse alternative narratives that surround the
possibility of the disappearance of print books, do
minated by fetishism, fears about the end of
humanism, and ideas of techno-fundamentalist progre
ss. We argue that, in order to comprehend
such narratives, we need to inscribe them in the br
oader history of media. The emergence of new
media, in fact, has often been accompanied by narra
tives about the possible disappearance of
older media: the introduction of television, for in
stance, inspired claims about the forthcoming
death of film and radio. As a recurrent narrative s
haping the reception of media innovation, the
myth of the disappearing medium helps us to make se
nse of the transformations that media
change provokes in our everyday life
Spin Glass and Antiferromagnetic Behaviour in a Diluted fcc Antiferromagnet
We report on a Monte Carlo study of a diluted Ising antiferromagnet on a fcc
lattice. This is a typical model example of a highly frustrated
antiferromagnet, and we ask, whether sufficient random dilution of spins does
produce a spin glass phase. Our data strongly indicate the existence of a spin
glass transition for spin--concentration : We find a divergent spin
glass susceptibility and a divergent spin glass correlation length, whereas the
antiferromagnetic correlation length saturates in this regime. Furthermore, we
find a first order phase transition to an antiferromagnet for ,
which becomes continuous in the range . Finite size scaling is
employed to obtain critical exponents. We compare our results with experimental
systems as diluted frustrated antiferromagnets as .Comment: 29 pages (revtex) and 10 figures uuencoded and Z-compresse
Mutation of a single residue, β-glutamate-20, alters protein–lipid interactions of light harvesting complex II
It is well established that assembly of the peripheral antenna complex, LH2, is required for proper photosynthetic membrane biogenesis in the purple bacterium Rhodobacter sphaeroides. The underlying interactions are, as yet, not understood. Here we examined the relationship between the morphology of the photosynthetic membrane and the lipid–protein interactions at the LH2–lipid interface. The non-bilayer lipid, phosphatidylethanolamine, is shown to be highly enriched in the boundary lipid phase of LH2. Sequence alignments indicate a putative lipid binding site, which includes β-glutamate-20 and the adjacent carotenoid end group. Replacement of β-glutamate-20 with alanine results in significant reduction of phosphatidylethanolamine and concomitant raise in phosphatidylcholine in the boundary lipid phase of LH2 without altering the lipid composition of the bulk phase. The morphology of the LH2 housing membrane is, however, unaffected by the amino acid replacement. In contrast, simultaneous modification of glutamate-20 and exchange of the carotenoid sphaeroidenone with neurosporene results in significant enlargement of the vesicular membrane invaginations. These findings suggest that the LH2 complex, specifically β-glutamate-20 and the carotenoids' polar head group, contribute to the shaping of the photosynthetic membrane by specific interactions with surrounding lipid molecules
Comprehensive review of the detection methods for synthetic cannabinoids and cathinones
Blood and liver phospholipids of albino rats at various stages of development of experimental pancreatitis
Microstoria di romanizzazione. Lo studio della tomba 304 della necropoli di Montebelluna-Posmon
L'articolo presenta lo studio di una tomba plurima della necropoli di Montebelluna Posmon (tomba 304) riferibile al II -I secolo a.C. Sono presentati i corredi (Casagrande), le monete (Asolati), le analisi antropologiche (Onisto), le iscrizioni venetiche e romane presenti nella tomba (Marinetti, Cresci), da cui si ricavano indizi sui processi culturali che hanno portato dalla fase veneta a quella romana. In particolare l'analisi delle fonti epigrafiche fornisce nuovi apporti al processo di trasformazione della formula onomastica, nei meccanismi di passaggio da quella di tradizione locale alla formula istituzionale romana
Phosphepines: Convenient Access to Phosphinidene Complexes
Reaction of o-diethynylbenzene with transition metal-complexed primary phosphines gives in a single base-induced step stable phosphepine complexes as confirmed by X-ray data. At 75-80 °C these phosphepines undergo clean cheletropic elimination of naphthalene to give transient carbene-like phosphinidene complexes that can be trapped in high yield by alkenes, alkynes, and alcohols. Copyright © 2005 American Chemical Society
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