Dark matter in satellite galaxies: Will future Iimaging Air Cherenkov Telescopes play a role?

Addressing the question about the importance of future Imaging Air Cherenkov Telescopes (IACTs) for indirect detection of Dark Matter (DM), I will review the results of a paper by Bringmann et al. (2008) in which the authors computed the gamma-ray flux from DM annihilation associated to the halos of two reference dwarf Spheroidal galaxies, Draco and Willman 1. The previously neglected contribution of Virtual Internal Bremsstrahlung is also taken into account, which produces, when present, a bump in the higher part of the energy spectrum. The boost factor is the quantity used to describe how far the experiment is from probing interesting DM scenarios and it is computed for the next generation of IACTs, namely MAGIC-II and CTA. Due to the presence of spectral features, the boost factors can vary, becoming dependent to the characteristics of the particular DM candidate, obstacling a clear statement about prospects of detection. However, at least for the case of Willman 1 observed by CTA, boost factors may be below 10, even without considering the effect of substructures or the Sommerfeld enhancement. This, added to the comparison with the prospects of detection by the Fermi satellite, clearly demonstrate that the answer to the question in the title is an affirmative one.     

Shape optimization for drag reduction in linked bodies using evolution strategies

We present results from the shape optimization of linked bodies for drag reduction in simulations of incompressible flow at moderate Reynolds numbers. The optimization relies on the covariance matrix adaptation evolution strategy (CMA-ES) and the flow simulations use vortex methods with the Brinkman penalization to enforce boundary conditions in complex bodies. We exploit the inherent parallelism of CMA-ES, by implementing a multi-host framework which allows for the distribution of the expensive cost function evaluations across parallel architectures, without being limited to one computing facility. This study repeats in silico for the first time Ingo Rechenberg’s pioneering wind tunnel experiments for drag reduction that led to the inception of evolution strategies. The simulations confirm that the results of these experimental studies indicate a flat plate is not the optimal solution for drag reduction in linked bodies. We present the vorticity field of the flow and identify the governing mechanisms for this drag reduction by the slightly corrugated linked plate configuration.     

Study of ITER equatorial port plug handling system and vacuum sealing interface

In the field of the ITER port plug engineering and integration task, CEA has contributed to define proposals concerning the port plugs vacuum sealing interface with the vessel flange and the equatorial plug handling.The 2001 baseline vacuum flange sealing consisted of TIG welding of a 316L strip plate on to U shapes. This arrangement presented some issues like welding access, implementation of tools, lip consumption, complex local leak test, continuous leak checking. Therefore, an alternate sealing solution based on the use of metallic gaskets is proposed. The different technical aspects are discussed to explain how this design can simplify the maintenance and deal with safety and vacuum requirements.The design of the mechanical attachment and vacuum sealing of the plug has constantly evolved, but the associated remote handling equipment was not systematically reviewed. An update of the cask and maintenance procedure was studied in order to design it in accordance with the last generic plug flange design. This includes a concept of a gripping system that uses the plug flange bolting area and, to help the remote handling process, a cantilever assisting system is suggested to increase the reliability of the transfer operation between vacuum vessel and cask.     

Coded transmissions for space links affected by solar scintillation: Baseband analysis

A thorough analysis of the behavior of error‐correcting codes over space links affected by solar scintillation is presented. The relevant channel parameters are fixed through the development of a model based on real missions' data. Both telecommand and telemetry links are considered in fast and slow fading conditions. Besides classical coherent modulation schemes, the possibility to use noncoherent modulation schemes is considered, to eliminate the problem of phase tracking. For the case of channels with very slow fading, the use of external interleavers or erasure coding is proposed to cope with error bursts.     

Effect of aldose reductase inhibition on glutathione redox status in erythrocytes of diabetic patients

Diabetic patients undergo a chronic oxidative stress. This phenomenon is demonstrated by low levels of reduced glutathione (GSH) levels. The NADPH used by glutathione reductase for the reduction of oxidized glutathione (GSSG) to GSH is also used by aldose reductase for the reduction of glucose to sorbitol through the polyol pathway. The competition for NADPH could be responsible for the decreased glutathione levels found in non-insulin-dependent diabetic patients. For this purpose, we investigated the effect of polyol pathway inhibition on the glutathione redox status in these patients. We measured GSH and GSSG levels in erythrocytes of non-insulin-dependent diabetic patients (n = 15) before and after 1 week of treatment with placebo, followed by 1 week of treatment with an aldose reductase inhibitor (tolrestat 200 mg/dl). We found lower GSH levels (7.7 +/- 1.4 mumol/g hemoglobin [Hb]), higher GSSG levels (0.35 +/- 0.09 mumol/g Hb), and lower GSH/GSSG ratios (23.9 +/- 7.7) in diabetics compared with controls (n = 15; 9.8 +/- 0.8 mumol/g Hb, P < .001; 0.17 +/- 0.02, P < .001; and 58.3 +/- 9.1, P < .001, respectively). We did not demonstrate any statistical difference after 1 week of treatment with placebo. In contrast, the treatment with tolrestat induced a significant increase in GSH (8.9 +/- 0.7 mumol/g Hb, P < .01), a decrease in GSSG (0.25 +/- 0.06 mumol/g Hb, P < .02), and an increase in the GSH/GSSG ratio (37.3 +/- 8.4, P < .01). These data strongly support the hypothesis that the polyol pathway plays an important role in the impairment of the glutathione redox status in diabetic patients.     

Redispersible Polymer Powders with High Bio-Based Content from Core–Shell Nanoparticles

Redispersible polymer powders (RDPPs), i.e., additives obtained from core–shell nanoparticles and commercialized in the form of a dry powder, find intensive application in the concrete industry. However, they are mainly produced from fossil resources. Therefore, the development of bio-based RDPPs is important to reduce the carbon footprint of these additives. In this work, two types of core–shell nanoparticles with a high percentage of bio-based content are synthesized and show to be good candidates as RDPPs. In the first case, up to 75% of bio-based content is obtained by combining lauryl acrylate, derived from coconut and palm kernel oil, as main core material, with isobornyl methacrylate, coming from pine resin, exploited to create the outer harder shell. In the second case, a degradable macromonomer obtained by the ring opening polymerization of lactide using 2-hydroxyethyl methacrylate as initiator is used as the core-forming monomer to obtain degradable RDPPs. In both cases, the particles are synthesized with a two-step emulsion polymerization process conducted in one pot and then spray-dried to obtain the RDPPs of interest. The morphology and redispersibility of the powders are characterized. Finally, their use as concrete additives is preliminarily assessed by evaluating their effect on changes in the surface morphologies of concrete specimens.     

In situ growth of well-dispersed CdS nanocrystals in semiconducting polymers

A straight synthetic route to fabricate hybrid nanocomposite films of well-dispersed CdS nanocrystals (NCs) in poly[2-methoxy-5-(2''-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is reported. A soluble cadmium complex [Cd(SBz)₂]₂·MI, obtained by incorporating a Lewis base (1-methylimidazole, MI) on the cadmium bis(benzyl)thiol, is used as starting reagent in an in situ thermolytic process. CdS NCs with spherical shape nucleate and grow well below 200°C in a relatively short time (30 min). Photoluminescence spectroscopy measurements performed on CdS/MEH-PPV nanocomposites show that CdS photoluminescence peaks are totally quenched inside MEH-PPV, if compared to CdS/PMMA nanocomposites, as expected due to overlapping of the polymer absorption and CdS emission spectra. The CdS NCs are well-dispersed in size and homogeneously distributed within MEH-PPV matrix as proved by transmission electron microscopy. Nanocomposites with different precursor/polymer weight ratios were prepared in the range from 1:4 to 4:1. Highly dense materials, without NCs clustering, were obtained for a weight/weight ratio of 2:3 between precursor and polymer, making these nanocomposites particularly suitable for optoelectronic and solar energy conversion applications.