940 research outputs found

    Managing art history fuzzy dates: an application in historico-geographical authority

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    Art history data management leads to express dates in a "fuzzy" way, which is not suitable for electronic processing. A standardized easy to use way of coding dates, maintaining all the semantics of the "natural" format, has been defined. Each date is, therefore, expressed (in the extended way) as a string of characters, with a well defined syntax, while it is really managed as a set of fields, which contain in a coded way, the same information that are contained in the extended format. The coded format of dates is easily and transparently managed by every Data Base Management System, allowing selection by exact values or by ranges. This conventional way of managing dates has been tested in the implementation of a DBMS based historico-geographical authority file

    Gravitational waveforms from the evaporating ACO cosmic string loop

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    The linearly polarized gravitational waveforms from a certain type of rotating, evaporating cosmic string - the Allen-Casper-Ottewill loop - are constructed and plotted over the lifetime of the loop. The formulas for the waveforms are simple and exact, and describe waves which attenuate self-similarly, with the amplitude and period of the waves falling off linearly with time.Comment: 30 pages, 16 figure

    The Problem of Inertia in Friedmann Universes

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    In this paper we study the origin of inertia in a curved spacetime, particularly the spatially flat, open and closed Friedmann universes. This is done using Sciama's law of inertial induction, which is based on Mach's principle, and expresses the analogy between the retarded far fields of electrodynamics and those of gravitation. After obtaining covariant expressions for electromagnetic fields due to an accelerating point charge in Friedmann models, we adopt Sciama's law to obtain the inertial force on an accelerating mass mm by integrating over the contributions from all the matter in the universe. The resulting inertial force has the form F=−kmaF = -kma, where k<1k < 1 depends on the choice of the cosmological parameters such as ΩM\Omega_{M}, ΩΛ\Omega_{\Lambda}, and ΩR\Omega_{R} and is also red-shift dependent.Comment: 10 page

    MeV Right-handed Neutrinos and Dark Matter

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    We consider the possibility of having a MeV right-handed neutrino as a dark matter constituent. The initial reason for this study was the 511 keV spectral line observed by the satellite experiment INTEGRAL: could it be due to an interaction between dark matter and baryons? Independently of this, we find a number of constraints on the assumed right-handed interactions. They arise in particular from the measurements by solar neutrino experiments. We come to the conclusion that such particles interactions are possible, and could reproduce the peculiar angular distribution, but not the rate of the INTEGRAL signal. However, we stress that solar neutrino experiments are susceptible to provide further constraints in the future.Comment: 7 pages, figure 1 changed, added reference

    Molecular signals from primordial clouds at high redshift

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    The possibility to detect cosmological signals from the post-recombination Universe is one of the main aims of modern cosmology. In a previous paper we emphasized the role that elastic resonant scattering through LiH molecules can have in dumping primary CBR anisotropies and raising secondary signals. Here we extend our analysis to all the evolutionary stages of a primordial cloud, starting with the linear phase, through the turn-around and to the non linear collapse. We have done calculations for proto-clouds in a CDM scenario and, more generally, for a set of clouds with various masses and various turn-around redshifts, in this case without referring to any particular structure formation scenario. We found that the first phase of collapse, for t/tfree−fall=0.05÷0.2t/t_{free-fall}=0.05\div 0.2 is the best one for simultaneous detection of the first two LiH rotational lines. The observational frequency falls between 30 and 250 GHz and the line width Δνν{\Delta \nu\over \nu} is between 10−510^{-5} and 10−410^{-4}. As far as we know this is the most favourable process to detect primordial clouds before they start star formation processes.Comment: 26 pages, uuencoded compressed postscript, 7 figures included. Accepted for publication in Ap.

    Surface Modification of Carbon Nanotube Networked Films with Au Nanoclusters for Enhanced N O 2 Gas Sensing Applications

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    Multiwalled carbon nanotube (MWCNT) films have been deposited by using plasma-enhanced chemical vapor deposition (PECVD) system onto alumina substrates, provided with 6 nm thick cobalt (Co) growth catalyst for remarkably improved gas sensing, at working temperature in the range of 100–. Functionalization of the MWCNTs with nanoclusters of gold (Au) sputtering has been performed to modify the surface of carbon nanotube networked films for enhanced and specific gas detection up to sub-ppm level. It is demonstrated that the gas sensitivity of the MWCNT-based sensors depends on Au-loading used as surface-catalyst. The gas response of MWCNT-based chemiresistor is attributed top-typeconductivity in the Au-modified semiconducting MWCNTs with a very good short-term repeatability and faster recovery. The sensor temperature of maximum sensitivity of the Au-functionalized MWCNTs is found to decrease with increasing Au-loading on their surface, and continuous gas monitoring at ppb level of is effectively performed with Au-modified MWCNT chemiresistors

    Emergency contraception: unresolved clinical, ethical and legal quandaries still linger

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    Emergency contraception (EC) has been prescribed for decades, in order to lessen the risk of unplanned and unwanted pregnancy following unprotected intercourse, ordinary contraceptive failure, or rape. EC and the linked aspect of unintended pregnancy undoubtedly constitute highly relevant public health issues, in that they involve women's self-determination, reproductive freedom and family planning. Most European countries regulate EC access quite effectively, with solid information campaigns and supply mechanisms, based on various recommendations from international institutions herein examined. However, there is still disagreement on whether EC drugs should be available without a physician's prescription and on the reimbursement policies that should be implemented. In addition, the rights of health care professionals who object to EC on conscience grounds have been subject to considerable legal and ethical scrutiny, in light of their potential to damage patients who need EC drugs in a timely fashion. Ultimately, reproductive health, freedom and conscience-based refusal on the part of operators are elements that have proven extremely hard to reconcile; hence, it is essential to strike a reasonable balance for the sake of everyone's rights and well-being
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