Space weathering, reddening and gardening of asteroids: A complex problem

The association of ordinary chondrites and their parent bodies through their visible and near infrared spectra is still a debate. In fact, many asteroids show reddened spectra, while the ordinary chondrites do not. In the framework of the space weathering of asteroid surfaces, the interpretation of the reddening, darkening, and depletion of band depths is not as simple as previously described. We present a summary of the recent results in the study of the reddening of the spectra. To date, different mechanisms have been proposed to explain some properties of spectra, but a complete scenario capable of reproducing the whole set of observations is still missing. (C) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved

Improving the discovery potential of charged Higgs bosons at the Tevatron and Large Hadron Collider

We outline several improvements to the experimental analyses carried out at Tevatron (Run 2) or simulated in view of the Large Hadron Collider (LHC) that could increase the scope of CDF/D0 and ATLAS/CMS in detecting charged Higgs bosonsComment: 6 pages, 4 figures, talk given at the `Seventh Workshop on High Energy Physics Phenomenology WHEPP-VII', Harish Chandra Research Institute, Allahabad, India, 4-15 January 2002 (to be published by PRAMANA - Journal of Physics

Breast metastasis and lung large-cell neuroendocrine carcinoma: first clinical observation

The lung Large-cell neuroendocrine carcinoma (LCNEC) is a very rare aggressive neuroendocrine tumor with a high propensy to metastasize and very poor prognosis. We report an atypical presentation of lung large-cell neuroendocrine carcinoma was diagnosed from a metastatic nodule on the breast. Our patient is a 59 years-old woman that presented in March 2014 non productive cough. A CT scan showed multiple brain, lung, adrenal gland and liver secondary lesions; moreover, it revealed a breast right nodule near the chest measuring 1.8 cm. The breast nodule and a lung lesions were biopsied and their histology and molecular diagnosis were LCNEC of the lung. To our knowledge, this is the first documented case of breast metastasis from LCNEC of the lung. Furthermore, breast metastasis from extramammary malignancy is uncommon and its diagnosis is difficult but important for proper management and prediction of prognosis. Therefore, a careful clinical history with a thorough clinical examination is needed to make the correct diagnosis. Moreover, metastasis to the breast should be considered in any patient with a known primary malignant tumor history who presents with a breast lump. Anyhow, pathological examination should be performed to differentiate the primary breast cancer from metastatic tumor. Therefore, an accurate diagnosis of breast metastases may not only avoid unnecessary breast resection, more importantly it is crucial to determine an appropriate and systemic treatment

Treatment volume of aedes albopictus with X rays generated from electrons

Irradiation is a common method used for sterilizing objects in several fields. In the entomology sector, insects are sterilized through irradiation and released in to the wild to sexually compete with the population at large reducing the chance for reproduction. This practice is the Sterile Insect Technique (SIT). Traditionally irradiation sources for SIT purpose are radioisotopes but many reasons compelled to getting efforts to develop other radiative technologies. Since gamma rays and electrons have similar sterilizing effects, the choice of source for SIT irradiation is based on considerations about penetration and environmental factors. Gamma irradiators are usually simpler to operate, and less expensive, than electron accelerators, at least within the range of power required for SIT applications. Currently, the increased difficulties to manage and ship radioisotopes is being successfully resolved by the introduction of novel X-ray irradiators that enable a safer use of irradiator machines and procedures for SIT applications. In the ENEA Frascati research center we developed irradiators for clinical radiotherapy consisting in a radiation converter from electrons to X-rays. Since X-rays penetrate deeper than the electrons from which they are generated, we used this technology in a configuration that delivers a uniform dose on large targets to irradiate insects for SIT aim. In this topic, we gained practical experience working with Aedes albopictus, a mosquito vector of various tropical diseases such as dengue and zika. Several dosimetric studies have been conducted to achieve male sterility without affecting male mating competitiveness in comparison with untreated males. Lower doses have been also tested on an Ae. albopictus strain modified with the bacterium Wolbachia, which also determines male sterility, to sterilize the females eventually escaping the sexing procedures preliminary to the releases of the males

The quiescent X-ray emission of three transient X-ray pulsars

We report on BeppoSAX and Chandra observations of three Hard X-Ray Transients in quiescence containing fast spinning (P<5 s) neutron stars: A 0538-66, 4U 0115+63 and V 0332+53. These observations allowed us to study these transients at the faintest flux levels thus far. Spectra are remarkably different from the ones obtained at luminosities a factor >10 higher, testifying that the quiescent emission mechanism is different. Pulsations were not detected in any of the sources, indicating that accretion of matter down to the neutron star surface has ceased. We conclude that the quiescent emission of the three X-ray transients likely originates from accretion onto the magnetospheric boundary in the propeller regime and/or from deep crustal heating resulting from pycnonuclear reactions during the outbursts.Comment: Accepted for publication on ApJ (5 pages and 2 figures

Continuous slice functional calculus in quaternionic Hilbert spaces

The aim of this work is to define a continuous functional calculus in quaternionic Hilbert spaces, starting from basic issues regarding the notion of spherical spectrum of a normal operator. As properties of the spherical spectrum suggest, the class of continuous functions to consider in this setting is the one of slice quaternionic functions. Slice functions generalize the concept of slice regular function, which comprises power series with quaternionic coefficients on one side and that can be seen as an effective generalization to quaternions of holomorphic functions of one complex variable. The notion of slice function allows to introduce suitable classes of real, complex and quaternionic $C^*$--algebras and to define, on each of these $C^*$--algebras, a functional calculus for quaternionic normal operators. In particular, we establish several versions of the spectral map theorem. Some of the results are proved also for unbounded operators. However, the mentioned continuous functional calculi are defined only for bounded normal operators. Some comments on the physical significance of our work are included.Comment: 71 pages, some references added. Accepted for publication in Reviews in Mathematical Physic

Bimagnon studies in cuprates with Resonant Inelastic X-ray Scattering at the O K edge. I - An assessment on La2CuO4 and a comparison with the excitation at Cu L3 and Cu K edges

We assess the capabilities of magnetic Resonant Inelastic X-ray Scattering (RIXS) at the O $K$ edge in undoped cuprates by taking La_{2}CuO_{4} as a benchmark case, based on a series of RIXS measurements that we present here. By combining the experimental results with basic theory we point out the fingerprints of bimagnon in the O $K$ edge RIXS spectra. These are a dominant peak around 450 meV, the almost complete absence of dispersion both with $\pi$ and $\sigma$ polarization and the almost constant intensity vs. the transferred momentum with $\sigma$ polarization. This behavior is quite different from Cu $L_3$ edge RIXS giving a strongly dispersing bimagnon tending to zero at the center of the Brillouin zone. This is clearly shown by RIXS measurements at the Cu $L_3$ edge that we present. The Cu $L_3$ bimagnon spectra and those at Cu $K$ edge - both from the literature and from our data - however, have the same shape. These similarities and differences are understood in terms of different sampling of the bimagnon continuum. This panorama points out the unique possibilities offered by O $K$ RIXS in the study of magnetic excitations in cuprates near the center of the BZ

Dislocation interactions mediated by grain boundaries

The dynamics of dislocation assemblies in deforming crystals indicate the emergence of collective phenomena, intermittent fluctuations and strain avalanches. In polycrystalline materials, the understanding of plastic deformation mechanisms depends on grasping the role of grain boundaries on dislocation motion. Here the interaction of dislocations and elastic, low angle grain boundaries is studied in the framework of a discrete dislocation representation. We allow grain boundaries to deform under the effect of dislocation stress fields and compare the effect of such a perturbation to the case of rigid grain boudaries. We are able to determine, both analytically and numerically, corrections to dislocation stress fields acting on neighboring grains, as mediated by grain boundary deformation. Finally, we discuss conclusions and consequences for the avalanche statistics, as observed in polycrystalline samples.Comment: 13 pages, 5 figure

Selection and reconstruction of the top quarks in the all-hadronic decays at a Linear Collider

A method of reconstruction of the top quarks produced in the process E+E- -> t\bar{t} -> 6 jets at a Linear Collider (LC) is proposed. The approach does not involve a kinematic fit, as well as assumptions on the invariant masses of the dijets originating from the decays of W bosons and, therefore, the method is expected to be less sensitive to theoretical and experimental uncertainties on the top-mass measurement than traditional reconstruction methods. For the first time, the reconstruction of the top quarks was investigated using the full LC detector simulation after taking into account the background arising from QCD multi-jet production.Comment: 22 pages, including 13 figures and 3 table