1,836 research outputs found
CONSTITUTIONAL PROBLEMS IN THE FIELD OF TAX RELIEF
The present study analyzes the constitutional issues relating to tax relief. We highlight how the doctrine and case law have raised particular problems relating to the constitutionality of the rules under consideration and especially that they create interference with the principle of saving clause and the principle of equality with regard to ability to pay.Tax Relief, principle of saving clause, principle of equality, ability to pay
One-point statistics and intermittency of induced electric field in the solar wind
The interplanetary induced electric field e=vxb is studied, using solar wind
time series. The probability distribution functions (PDFs) of the electric
field components are measured from the data and their non-gaussianity is
discussed. Moreover, for the first time we show that the electric field
turbulence is characterized by intermittency. This point is addressed by
studying, as usual, the scaling of the PDFs of field increments, which allows a
quantitative characterization of intermittency.Comment: Accepted for publication on Europhysics Letters, April 22th, 200
The Solar Wind as a Turbulence Laboratory
In this review we will focus on a topic of fundamental importance for both astrophysics and plasma physics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state. This subject will be treated within the context of the expanding solar wind and the most meaningful advances in this research field will be reported emphasizing the results obtained in the past decade or so. As a matter of fact, Helios inner heliosphere and Ulysses' high latitude observations, recent multi-spacecrafts measurements in the solar wind (Cluster four satellites) and new numerical approaches to the problem, based on the dynamics of complex systems, brought new important insights which helped to better understand how turbulent fluctuations behave in the solar wind. In particular, numerical simulations within the realm of magnetohydrodynamic (MHD) turbulence theory unraveled what kind of physical mechanisms are at the basis of turbulence generation and energy transfer across the spectral domain of the fluctuations. In other words, the advances reached in these past years in the investigation of solar wind turbulence now offer a rather complete picture of the phenomenological aspect of the problem to be tentatively presented in a rather organic way
Power Laws in Solar Flares: Self-Organized Criticality or Turbulence?
We study the time evolution of Solar Flares activity by looking at the
statistics of quiescent times between successive bursts. The
analysis of 20 years of data reveals a power law distribution with exponent
which is an indication of complex dynamics with long
correlation times. The observed scaling behavior is in contradiction with the
Self-Organized Criticality models of Solar Flares which predict Poisson-like
statistics. Chaotic models, including the destabilization of the laminar phases
and subsequent restabilization due to nonlinear dynamics, are able to reproduce
the power law for the quiescent times. In the case of the more realistic Shell
Model of MHD turbulence we are able to reproduce all the observed
distributions.Comment: 4 pages, 4 postscript figures. Submitted to Physical Review Letter
Sign Singularity of the Magnetic Helicity from in Situ Solar Wind Observations
Some turbulent signed measures show a singularity related to extreme oscillations in sign, the scaling behavior of cancellations between positive and negative contributions being characterized by the cancellation exponent κ. Using in situ observations of magnetic fluctuations in the solar wind, we show that magnetic helicity is sign singular, a property that underlies the dominance of a single sign of polarization of fluctuations at small scales. We recover a statistical correlation between κ and the bulk solar wind speed when any correlation has been found between κ and the distance from the Sun. Even if the usual models of magnetic fluctuations based on random phases are able to reproduce (in a statistical sense) the gross features of helicity fluctuations, they cannot reproduce the behavior of sign singularity
An Application of ELECTRE Tri to Support Innovation
In relation to the economic crisis, the airports were pressed from their national civil aviation authorities and from the market
to lower their costs and improve their capability in organizing the supply of public facilities. Some airports reacted to this
situation improving their efficiency in invoicing and collecting user charges. An enterprise that supplies different services
to the Italian Aviation Authority and to several Italian companies who are airport concessionaires decided to analyse the
Italian airport revenues from off-flight services, in order to compare their different results and help them improve their
product offerings and identify new products’ value drivers.
To meet this requirement, an outranking method, ELECTRE Tri, was used to evaluate the marginal and overall activation
of each Italian airport in reacting to the crisis and making profit by organizing public facilities and services that are different
from the classic air navigation services on the ground. The choice of the method and the adopted procedure were motivated
by the difficulties in reliable data acquisition, comparison of different and almost incomparable situations and preference
elicitation, without the involvement of the actual decision makers and, in relation to a sequence of model versions, different
in terms of problem structuring and parameters definition.
A collaborative procedure of model structuring and incremental result analysis and several ELECTRE Tri applications,
assigning each airport to a specific category, were oriented to the generation of a ‘robust’ model and a clear result, to read
and synthesize all the information elements, understand the situation and acquire a shared vision of the problem, orient
the process of information acquisition and support the definition of some improving actions
Election Manipulation in Social Networks with Single-Peaked Agents
Several elections run in the last years have been characterized by attempts
to manipulate the result of the election through the diffusion of fake or
malicious news over social networks. This problem has been recognized as a
critical issue for the robustness of our democracy. Analyzing and understanding
how such manipulations may occur is crucial to the design of effective
countermeasures to these practices.
Many studies have observed that, in general, to design an optimal
manipulation is usually a computationally hard task. Nevertheless, literature
on bribery in voting and election manipulation has frequently observed that
most hardness results melt down when one focuses on the setting of (nearly)
single-peaked agents, i.e., when each voter has a preferred candidate (usually,
the one closer to her own belief) and preferences of remaining candidates are
inversely proportional to the distance between the candidate position and the
voter's belief. Unfortunately, no such analysis has been done for election
manipulations run in social networks.
In this work, we try to close this gap: specifically, we consider a setting
for election manipulation that naturally raises (nearly) single-peaked
preferences, and we evaluate the complexity of election manipulation problem in
this setting: while most of the hardness and approximation results still hold,
we will show that single-peaked preferences allow to design simple, efficient
and effective heuristics for election manipulation
A novel combination of triple metachronous malignancies of the kidney, oropharynx and prostate. A case report
Synchronous or metachronous malignancies are a rare event, with an incidence rate that increases with age. The present study reports the case of a 70-year-old Caucasian male who was referred to the outpatient office of the Urology Unit, Sapienza University of Rome (Latina, Italy) due to lower urinary tract symptoms. An abdominal ultrasound investigation was performed that demonstrated the presence of a right renal mass. The patient underwent right radical nephrectomy, which resulted in the definitive diagnosis of clear cell type renal cell carcinoma. The patient was eventually diagnosed with triple primary metachronous cancer consisting of renal clear cell carcinoma, prostate adenocarcinoma and squamous cell carcinoma of the oropharynx (palatine tonsil). To the best of our knowledge, this combination of primary neoplasms has not previously been documented
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