940 research outputs found
Managing art history fuzzy dates: an application in historico-geographical authority
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
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
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 by integrating over the contributions from all the matter in the
universe. The resulting inertial force has the form , where
depends on the choice of the cosmological parameters such as ,
, and and is also red-shift dependent.Comment: 10 page
MeV Right-handed Neutrinos and Dark Matter
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
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
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 is between
and . 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
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
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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