Dimensional effects on the tunneling conductivity of gold-implanted nanocomposite films

We study the dependence of the electrical conductivity on the gold concentration of Au-implanted polymethylmethacrylate (PMMA) and alumina nanocomposite thin films. For Au contents larger than a critical concentration, the conductivity of Au-PMMA and Au-alumina is well described by percolation in two dimensions, indicating that the critical correlation length for percolation is larger than the thickness of the films. Below the critical loading, the conductivity is dominated by tunneling processes between isolated Au particles dispersed in PMMA or alumina continuous matrices. Using an effective medium analysis of the tunneling conductivity, we show that Au-PMMA behaves as a tunneling system in two dimensions, as the film thickness is comparable to the mean Au particle size. On the contrary, the conductivity of Au-alumina films is best described by tunneling in three dimensions, although the film thickness is only a few times larger than the particle size. We interpret the enhancement of the effective dimensionality of Au-alumina films in the tunneling regime as due to the larger film thickness as compared to the mean interparticle distances.Comment: 7 pages, 7 figure

Sola est non territa virgo. Il mito di Aracne e le ambigue trame della tessitura

The topic of the discussion offers an opportunity to more deeply consider a myth connected to the theme of weaving: the tragic story of the weaver Arachne, whose story depends almost exclusively on the story by Ovid, developed in the first part of Book VI of the Metamorphoses and placed inside a series of myths that deal with the theme of punished hybris. The reading of the Ovidian myth and the analysis of the evidences in the iconographic tradition lie well within the project “MetaMArS. The Metamorphoses of Ovid. Myth, Art, Society”, active in the Department of Archaeology, University of Padua, sprung from the idea of an ambitious revision of Ovid’s Metamorphoses from the perspectives of art history, with the aim to reconstruct visual models that could have influenced the Ovidian narration, or, viceversa, the effect of certain passages written by Ovid on visual interpretations of the myth. Introducing the actual contest with Pallas, the poet inserts a series of observations on Arachne’s gestures (“… it was not only worth admiring the finished product but also while she made them, it was the spectacle of making the art …”), which constitutes one of the more concrete evidences of fascination exercised by the act of weaving on an artist who creates his art through words

Exploiting the Symmetry of the Resonator Mode to Enhance PELDOR Sensitivity.

Pulsed electron paramagnetic resonance (EPR) spectroscopy using microwaves at two frequencies can be employed to measure distances between pairs of paramagnets separated by up to 10 nm. The method, combined with site-directed mutagenesis, has become increasingly popular in structural biology for both its selectivity and capability of providing information not accessible through more standard methods such as nuclear magnetic resonance and X-ray crystallography. Despite these advantages, EPR distance measurements suffer from poor sensitivity. One contributing factor is technical: since 65 MHz typically separates the pump and detection frequencies, they cannot both be located at the center of the pseudo-Lorentzian microwave resonance of a single-mode resonator. To maximize the inversion efficiency, the pump pulse is usually placed at the center of the resonance, while the observer frequency is placed in the wing, with consequent reduction in sensitivity. Here, we consider an alternative configuration: by spacing pump and observer frequencies symmetrically with respect to the microwave resonance and by increasing the quality factor, valuable improvement in the signal-to-noise ratio can be obtained

Limits on Pop III star formation with the most iron-poor stars

We study the impact of star-forming mini-haloes, and the Initial Mass Function (IMF) of Population III (Pop III) stars, on the Galactic halo Metallicity Distribution Function (MDF) and on the properties of C-enhanced and C-normal stars at [Fe/H]<-3. For our investigation we use a data-constrained merger tree model for the Milky Way formation, which has been improved to self-consistently describe the physical processes regulating star-formation in mini-haloes, including the poor sampling of the Pop III IMF. We find that only when star-forming mini-haloes are included the low-Fe tail of the MDF is correctly reproduced, showing a plateau that is built up by C-enhanced metal-poor (CEMP) stars imprinted by primordial faint supernovae. The incomplete sampling of the Pop III IMF in inefficiently star-forming mini-haloes (< $10^{-3}$ $M_\odot$/yr) strongly limits the formation of Pair Instability Supernovae (PISNe), with progenitor masses $m_{\rm popIII}$=[140-260] $M_\odot$, even when a flat Pop III IMF is assumed. Second-generation stars formed in environments polluted at >50% level by PISNe are thus extremely rare, corresponding to $\approx$ 0.25% of the total stellar population at [Fe/H]<-2, which is consistent with recent observations. The low-Fe tail of the MDF strongly depends on the Pop III IMF shape and mass range. Given the current statistics, we find that a flat Pop III IMF model with $m_{\rm popIII}$=[10-300] $M_\odot$ is disfavoured by observations. We present testable predictions for Pop III stars extending down to lower masses, with $m_{\rm popIII}$=[0.1-300] $M_\odot$.Comment: 15 pages, 11 figures. Accepted for publication in MNRAS. The only change is the correction of a mistake in the list of author

Long-term outcome of everolimus treatment in transplant patients

Maurizio Salvadori, Elisabetta BertoniRenal Unit, Careggi University Hospital, Florence, ItalyAbstract: The authors review the use of everolimus in long-term studies both in renal and heart transplantation. The pharmacokinetic and pharmacodynamic differences between everolimus and its parent drug, sirolimus are discussed. The improved pharmacokinetic, in particular the improved bioavailability, the reduced half-time and the reduced binding to plasma protein makes everolimus the first choice among the proliferation signal inhibitors. Everolimus is given in almost all studies in association with cyclosporine, but fixed doses of this drug can cause nephrotoxicity. The first studies used everolimus and CsA in fixed doses, but later studies with reduced CsA doses revealed which revealed improved outcomes. Finally, therapeutic drug monitoring became the better choice for both drugs. Recently very high everolimus exposure allowed the use of very low CsA exposure with improvement of the worse side effects linked to the CsA standard dose. The Zeus study revealed a complete and safe CsA withdrawal, thanks to everolimus and mycophenolic acid. In heart transplantation, everolimus resulted in improved outcomes with respect to antiproliferative drugs such as mycophenolic acid and azathioprine. Along with antirejection properties, everolimus provided evidence for antiproliferative effects on several cells. This resulted in fewer viral infections (mainly CMV), anti-atherosclerotic properties (mainly important in heart transplantation, and antineoplastic effect. The latter activity resulted in lower cancer incidence in transplant patients treated by everolimus. An important piece of evidence for this activity is documented by the use of everolimus in the treatment of some cancers, including renal cancer, neuroendocrine cancers and hepatocellular cancers, also outside the field of transplantation.Keywords: everolimus, renal transplantation, heart transplantation, CNI minimization, CNI withdrawa

Galaxy formation with radiative and chemical feedback

Here we introduce GAMESH, a novel pipeline which implements self-consistent radiative and chemical feedback in a computational model of galaxy formation. By combining the cosmological chemical-evolution model GAMETE with the radiative transfer code CRASH, GAMESH can post process realistic outputs of a N-body simulation describing the redshift evolution of the forming galaxy. After introducing the GAMESH implementation and its features, we apply the code to a low-resolution N-body simulation of the Milky Way formation and we investigate the combined effects of self-consistent radiative and chemical feedback. Many physical properties, which can be directly compared with observations in the Galaxy and its surrounding satellites, are predicted by the code along the merger-tree assembly. The resulting redshift evolution of the Local Group star formation rates, reionisation and metal enrichment along with the predicted Metallicity Distribution Function of halo stars are critically compared with observations. We discuss the merits and limitations of the first release of GAMESH, also opening new directions to a full implementation of feedback processes in galaxy formation models by combining semi-analytic and numerical methods.Comment: This version has coloured figures not present in the printed version. Submitted to MNRAS, minor revision

Observações sobre a biologia de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera-Noctuidae) em trigo.

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