60 research outputs found
Are OPERA neutrinos faster than light because of non-inertial reference frames?
Recent results from the OPERA experiment reported a neutrino beam traveling
faster than light. The experiment measured the neutrino time of flight (TOF)
over a baseline from the CERN to the Gran Sasso site. The neutrino beam arrives
60 ns earlier than a light ray would do. Because the result has an enormous
impact on science, it might be worth double-checking the time definitions with
respect to the non-inertial system in which the neutrino travel time was
measured. Potential problems in the OPERA data analysis connected with the
definition of the reference frame and time synchronization are emphasized. We
aim to investigate the synchronization of non-inertial clocks on Earth by
relating this time to the proper time of an inertial observer at Solar System
Barycenter(SSB). The Tempo2 software was used to time-stamp events observed on
the geoid with respect to the SSB inertial observer time. Neutrino results from
OPERA might carry the fingerprint of non-inertial effects. The CERN-Gran Sasso
clock synchronization is accomplished by applying corrections that depend on
special and general relativistic time dilation effects at the clocks, depending
on the position of the clocks in the solar system gravitational well. As a
consequence, TOF distributions are centered on values shorter by tens of ns
than expected, integrating over a period from April to December, longer if
otherwise. It is worth remarking that the OPERA runs have always been carried
out from April/May to November. If the analysis by Tempo2 holds for the OPERA
experiment, the excellent measurement by the OPERA collaboration will turn into
a proof of the General Relativity theory in a weak field approximation. The
analysis presented here is falsifiable because it predicts that performing the
experiment from January to March/April, the neutrino beam will be detected to
arrive 50 ns later than light.Comment: 5 pages, 4 figures, accepted for publication in Astronomy and
Astrophysics Letter
ISLAMIC POTTERY PRODUCTION IN EASTERN SICILY (10th-11th CENTURIES): PRELIMINARY ARCHAEOMETRIC DATA ON LOCAL AND IMPORTED PRODUCTS FROM PATERNÒ (SICILY).
From the 9th to the 11th century, Sicily has been part of the Islamic oecumene, the dār al-Islām. Up until now, very few studies have been carried out on the centres of pottery production of this period, and most of them concern the Emiral capital of the isle, Palermo. The archaeometric data obtained with chemical and minero-petrographic analyses on Islamic pottery found in Paternò – a town situated in the southwestern slope of Mt. Etna – has provided a certain number of issues of very important matter. The selection of the samples has been made among the archaeological finds coming from the excavation near the church of Cristo al Monte, on the hilltop, which represented the inner part of the medieval madīna. The mineralogical and chemical characterization of the ceramic body has been attained using optical microscopy on thin sections and X-ray fluorescence respectively, in order to define the probable provenance of each sample. Further information of technological matter has been provided using X-Ray diffraction on powdered samples, which furnishes mineralogical data useful to hypothesise the firing temperatures: the main task attained on this issue was the focus on the self-slipped ware with salted water, one of the main technological class in Islamic Sicily. Finally, energy dispersive X-Ray fluorescence was adopted for a preliminary investigation of pigments used to decorate the lead glazed pottery. The issues related to both the local and imported pots – the latter represented almost completely by Palermo"s products – provided some important historical and archaeological information about the means of Sicilian pottery production during this important period
Galvanic Deposition of Hydroxyapatite/Chitosan/Collagen Coatings on 304 Stainless Steel
The galvanic deposition method was used to deposit Hydroxyapatite/Chitosan/Collagen coatings on 304 stainless steel. Galvanic deposition is an alternative and valid way to fabricate bio-coatings with high biocompatibility and good anticorrosion properties. Physical-chemical characterizations were carried out to investigate chemical composition and morphology of the samples. Coatings consist of a mixture of calcium phosphate (Brushite and Hydroxyapatite) with chitosan and collagen. Corrosion tests were performed in the simulated body fluid (SBF) after different aging times. Results show that, in comparison with bare 304 stainless steel, coating shifts corrosion potential to anodic values and reduces corrosion current density. Nevertheless, the aging in SBF led to a completely conversion of brushite into hydroxyapatite. The release of metal ions, measured after 21 days of aging in SBF solution, is very low due to the presence of coating that slow-down the corrosion rate of steel
Thermal and morphological investigations of alkali activated materials based on Sicilian volcanic precursors (Italy)
Insights on thermal behavior and microstructures of AAMs based on Sicilian volcanic precursors (i.e.,
volcanic ash, "ghiara" and pumice) have been performed. A multidisciplinary approach by means of
thermogravimetric analysis coupled to Fourier Transform Infrared Spectroscopy and X-ray Computed
Microtomography has been used with the aim to define the influence of reactants involved in the process.
The obtained results show: i) the increase of metakaolin shifts the gas emission toward lower
temperatures; ii) the positive relation between mass loss and liquid/solid ratio; iii) the influence of particle
size of precursors on the pore development
Raman spectroscopy potentiality in the study of geopolymers reaction degree
AbstractAlkali‐activated materials (AAMs) and "geopolymers" are inorganic polymeric materials obtained by mixing of solid aluminosilicate precursors with an alkaline solution (generally, KOH or NaOH and Na2SiO3 mixed in various ratios). This class of aluminosilicate materials has emerged as a greener alternative to traditional concrete, for large‐scale as well as for niche applications such as conservation and restoration of built heritage. In this work we apply Raman spectroscopy both to aluminosilicate precursors (metakaolin, pumice, volcanic ash, volcanic soils, clayey sediments, ceramic waste) and to the respective AAMs. In the field of vibrational spectroscopy, Raman is much less employed in the literature with respect to Fourier transform infrared (FTIR) to have insights into the alkali activation process from a molecular point of view. The aim of this paper is to investigate the potentiality of a Raman approach to the comparison of the employed raw materials with the respective AAMs. Raman analyses during the first hours of geopolymerization were also carried out on the clayey sediments and ceramic waste‐based products. The results, differentiated according to the employed precursors, exhibit spectra relative to crystalline and amorphous phases that can give an indication about the newly formed aluminosilicate gel
Impact of different driving cycles and operating conditions on CO2 emissions and energy management strategies of a Euro-6 hybrid electric vehicle
Although Hybrid Electric Vehicles (HEVs) represent one of the key technologies to reduce
CO2 emissions, their effective potential in real world driving conditions strongly depends on the
performance of their Energy Management System (EMS) and on its capability to maximize the
efficiency of the powertrain in real life as well as during Type Approval (TA) tests. Attempting to
close the gap between TA and real world CO2 emissions, the European Commission has decided
to introduce from September 2017 theWorldwide Harmonized Light duty Test Procedure (WLTP),
replacing the previous procedure based on the New European Driving Cycle (NEDC). The aim of
this work is the analysis of the impact of different driving cycles and operating conditions on CO2
emissions and on energy management strategies of a Euro-6 HEV through the limited number of
information available from the chassis dyno tests. The vehicle was tested considering different initial
battery State of Charge (SOC), ranging from 40% to 65%, and engine coolant temperatures, from
7 C to 70 C. The change of test conditions from NEDC to WLTP was shown to lead to a significant
reduction of the electric drive and to about a 30% increase of CO2 emissions. However, since the
specific energy demand of WLTP is about 50% higher than that of NEDC, these results demonstrate
that the EMS strategies of the tested vehicle can achieve, in test conditions closer to real life,
even higher efficiency levels than those that are currently evaluated on the NEDC, and prove the
effectiveness of HEV technology to reduce CO2 emissions
Zinc-finger-based transcriptional repression of rhodopsin in a model of dominant retinitis pigmentosa
Despite the recent success of gene-based complementation approaches for genetic recessive traits, the development of therapeutic strategies for gain-of-function mutations poses great challenges. General therapeutic principles to correct these genetic defects mostly rely on post-transcriptional gene regulation (RNA silencing). Engineered zinc-finger (ZF) protein-based repression of transcription may represent a novel approach for treating gain-of-function mutations, although proof-of-concept of this use is still lacking. Here, we generated a series of transcriptional repressors to silence human rhodopsin (hRHO), the gene most abundantly expressed in retinal photoreceptors. The strategy was designed to suppress both the mutated and the wild-type hRHO allele in a mutational-independent fashion, to overcome mutational heterogeneity of autosomal dominant retinitis pigmentosa due to hRHO mutations. Here we demonstrate that ZF proteins promote a robust transcriptional repression of hRHO in a transgenic mouse model of autosomal dominant retinitis pigmentosa. Furthermore, we show that specifically decreasing the mutated human RHO transcript in conjunction with unaltered expression of the endogenous murine Rho gene results in amelioration of disease progression, as demonstrated by significant improvements in retinal morphology and function. This zinc-finger-based mutation-independent approach paves the way towards a ‘repression–replacement’ strategy, which is expected to facilitate widespread applications in the development of novel therapeutics for a variety of disorders that are due to gain-of-function mutations
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