Hydrogen Bonding Donor–Acceptor Carbon Nanostructure

The natural process of photosynthesis is paradigmatic in converting sunlight into energy. This complicated process requires a cascade of energy- and electron-transfer events in a highly organised matrix of electron–donor, electron–acceptor and antennae units and has prompted researchers to emulate it. In fact, energy- and electron-transfer processes play a pivotal role in molecular-scale optoelectronics. In this chapter we compile a number of remarkable examples of noncovalent aggregates formed by the combination of carbon-based electroactive species (fullerenes and carbon nanotubes) hydrogen bonded with a variety of moieties. We will show that: (a) the connection of complementary electroactive species by means of H bonds in C60-based donor–acceptor ensembles is at least as efficient as that found in covalently connected systems; (b) hydrogen-bonding fullerene chemistry is a versatile concept to construct supramolecular polymers, and (c) H-bonding interactions is contributing to create very appealing carbon-nanotube-based donor–acceptor supramolecular architectures

An agent-based approach for the design of the future european air traffic management system

This paper describes an agent-based approach for the simulation of air traffic management (ATM) in Europe that was designed to help analyze proposals for future ATM systems. This approach is able to represent new collaborative deci-sion processes for flow traffic management, it uses an intermediate level of ab-straction (useful for simulations at larger scales), and was designed to be a practi-cal tool (open and reusable) for the development of different ATM studies. It was successfully applied in three studies related to the design of future ATM systems in Europe

Polarization of the WMAP Point Sources

The detection of polarized sources in the WMAP 5-year data is a very difficult task. The maps are dominated by instrumental noise and only a handful of sources show up as clear peaks in the Q and U maps. Optimal linear filters applied at the position of known bright sources detect with a high level of significance a polarized flux P from many more sources, but estimates of P are liable to biases. Using a new technique, named the "filtered fusion technique", we have detected in polarization, with a significance level greater than 99.99% in at least one WMAP channel, 22 objects, 5 of which, however, do not have a plausible low radio frequency counterpart and are therefore doubtful. Estimated polarized fluxes P < 400 mJy at 23 GHz were found to be severely affected by the Eddington bias. The corresponding polarized flux limit for Planck/LFI at 30 GHz, obtained via realistic simulations, is 300 mJy. We have also obtained statistical estimates of, or upper limits to the mean polarization degrees of bright WMAP sources at 23, 33, 41, and 61 GHz, finding that they are of a few percent.Comment: 10 pages, 6 figures. Accepted for publication in Ap

Necrotizing pneumonia due to Mycoplasma in children: an uncommon presentation of a common disease

Mycoplasma pneumoniae is a common respiratory pathogen, especially in children, responsible for community-acquired pneumonia. Although, in most cases, infections caused by this bacterium follow a benign self-limited clinical course, cases of severe respiratory infections have been reported. We present two pediatric cases of necrotizing pneumonia due to Mycoplasma pneumoniae. Both patients initially presented with low-grade fever, cough and mild respiratory symptoms, however, imaging techniques showed necrotizing pneumonia. Initially, a typical bacterial pneumonia was suspected, so antibiotic empiric regimen did not included macrolides. When clinical evolution was not adequate, antibiotic treatment was modified in order to provide coverage to unusual pathogens. Both patients finally recovered once Mycoplasma was suspected, and oral macrolides were added to their treatment. Although M. pneumoniae is a rare cause of necrotizing pneumonia, it must be considered, when usual antibiotic empiric therapy is not being successful. Before thinking of uncommon germs, we must remember that: ‘The unusual presentation of a common disease is generally more likely than the usual presentation of an uncommon disease’

Trigonometry of spacetimes: a new self-dual approach to a curvature/signature (in)dependent trigonometry

A new method to obtain trigonometry for the real spaces of constant curvature and metric of any (even degenerate) signature is presented. The method encapsulates trigonometry for all these spaces into a single basic trigonometric group equation. This brings to its logical end the idea of an absolute trigonometry, and provides equations which hold true for the nine two-dimensional spaces of constant curvature and any signature. This family of spaces includes both relativistic and non-relativistic homogeneous spacetimes; therefore a complete discussion of trigonometry in the six de Sitter, minkowskian, Newton--Hooke and galilean spacetimes follow as particular instances of the general approach. Any equation previously known for the three classical riemannian spaces also has a version for the remaining six spacetimes; in most cases these equations are new. Distinctive traits of the method are universality and self-duality: every equation is meaningful for the nine spaces at once, and displays explicitly invariance under a duality transformation relating the nine spaces. The derivation of the single basic trigonometric equation at group level, its translation to a set of equations (cosine, sine and dual cosine laws) and the natural apparition of angular and lateral excesses, area and coarea are explicitly discussed in detail. The exposition also aims to introduce the main ideas of this direct group theoretical way to trigonometry, and may well provide a path to systematically study trigonometry for any homogeneous symmetric space.Comment: 51 pages, LaTe

Fip1 is a multivalent interaction scaffold for processing factors in human mRNA 3' end biogenesis

3' end formation of most eukaryotic mRNAs is dependent on the assembly of a ~1.5 MDa multiprotein complex, that catalyzes the coupled reaction of pre-mRNA cleavage and polyadenylation. In mammals, the cleavage and polyadenylation specificity factor (CPSF) constitutes the core of the 3' end processing machinery onto which the remaining factors, including cleavage stimulation factor (CstF) and poly(A) polymerase (PAP), assemble. These interactions are mediated by Fip1, a CPSF subunit characterized by high degree of intrinsic disorder. Here, we report two crystal structures revealing the interactions of human Fip1 (hFip1) with CPSF30 and CstF77. We demonstrate that CPSF contains two copies of hFip1, each binding to the zinc finger (ZF) domains 4 and 5 of CPSF30. Using polyadenylation assays we show that the two hFip1 copies are functionally redundant in recruiting one copy of PAP, thereby increasing the processivity of RNA polyadenylation. We further show that the interaction between hFip1 and CstF77 is mediated via a short motif in the N-terminal 'acidic' region of hFip1. In turn, CstF77 competitively inhibits CPSF-dependent PAP recruitment and 3' polyadenylation. Taken together, these results provide a structural basis for the multivalent scaffolding and regulatory functions of hFip1 in 3' end processing