4,408 research outputs found
Computing Probabilistic Bisimilarity Distances for Probabilistic Automata
The probabilistic bisimilarity distance of Deng et al. has been proposed as a
robust quantitative generalization of Segala and Lynch's probabilistic
bisimilarity for probabilistic automata. In this paper, we present a
characterization of the bisimilarity distance as the solution of a simple
stochastic game. The characterization gives us an algorithm to compute the
distances by applying Condon's simple policy iteration on these games. The
correctness of Condon's approach, however, relies on the assumption that the
games are stopping. Our games may be non-stopping in general, yet we are able
to prove termination for this extended class of games. Already other algorithms
have been proposed in the literature to compute these distances, with
complexity in and \textbf{PPAD}. Despite the
theoretical relevance, these algorithms are inefficient in practice. To the
best of our knowledge, our algorithm is the first practical solution.
The characterization of the probabilistic bisimilarity distance mentioned
above crucially uses a dual presentation of the Hausdorff distance due to
M\'emoli. As an additional contribution, in this paper we show that M\'emoli's
result can be used also to prove that the bisimilarity distance bounds the
difference in the maximal (or minimal) probability of two states to satisfying
arbitrary -regular properties, expressed, eg., as LTL formulas
Large System Analysis of Game-Theoretic Power Control in UWB Wireless Networks with Rake Receivers
This paper studies the performance of partial-Rake (PRake) receivers in
impulse-radio ultrawideband wireless networks when an energy-efficient power
control scheme is adopted. Due to the large bandwidth of the system, the
multipath channel is assumed to be frequency-selective. By using noncooperative
game-theoretic models and large system analysis, explicit expressions are
derived in terms of network parameters to measure the effects of self- and
multiple-access interference at a receiving access point. Performance of the
PRake is compared in terms of achieved utilities and loss to that of the
all-Rake receiver.Comment: To appear in the Proceedings of the 8th IEEE International Workshop
on Signal Processing Advances in Wireless Communications (SPAWC), Helsinki,
Finland, June 17-20, 200
Complete Axiomatization for the Bisimilarity Distance on Markov Chains
In this paper we propose a complete axiomatization of the bisimilarity distance of Desharnais et al. for the class of finite labelled Markov chains. Our axiomatization is given in the style of a quantitative extension of equational logic recently proposed by Mardare, Panangaden, and Plotkin (LICS\u2716) that uses equality relations t =_e s indexed by rationals, expressing that "t is approximately equal to s up to an error e".
Notably, our quantitative deductive system extends in a natural way the equational system for probabilistic bisimilarity given by Stark and Smolka by introducing an axiom for dealing with the Kantorovich distance between probability distributions
Maxillary nerve block: A comparison between the greater palatine canal and high tuberosity approaches.
Aim: Analgesia and anxiolysis during dental procedures are important for dental care and
patient compliance. This study aims to compare two classical maxillary nerve block (MNB)
techniques: the greater palatine canal (GPC) and the high tuberosity (HT) approaches,
seldom used in routine dental practice.
Methods: The study was conducted on 30 patients, scheduled for sinus lift surgery, who
were randomly divided into 2 groups: the GPC approach to the MNB was used in 15 and the
HT one in the other 15 patients. Anxiolysis was also used, depending on the results of the
pre- preoperative assessment. Patients\u2019 sensations/pain during the procedure, details about
anesthesia, and the dentist\u2019s considerations were all recorded. Data are expressed as mean
\ub1SD. Statistical tests including ANOVA, \u3c72 following Yates correction and linear regression
analysis were carried out. A < 0.05 p value was considered significant.
Results: Study results showed that the anesthesia was effective and constant in the molar
and premolar area. Additional infiltrations of local anesthetics were necessary for vestibular
and palatal areas in the anterior oral cavity, respectively, in the GPC and HT groups. The
two techniques were equally difficult to carry out in the dentist\u2019s opinion. There were
no differences in pain or unpleasant sensations between the two groups, nor were any
anesthesia-related complications reported.
Conclusion: The GPC approach ensures effective anesthesia in the posterior maxillary
region as far as both the dental pulp and the palatal/vestibular mucous membranes are
concerned; the HT approach did not guarantee adequate anesthesia of the pterygopalatine
branch of the maxillary nerve. These regional anesthesia techniques were characterized
by a low incidence of intra and postoperative pain, no noteworthy complications, and high
patient satisfaction
On the Metric-Based Approximate Minimization of Markov Chains
We address the behavioral metric-based approximate minimization problem of Markov Chains (MCs), i.e., given a finite MC and a positive integer k, we are interested in finding a k-state MC of minimal distance to the original. By considering as metric the bisimilarity distance of Desharnais at al., we show that optimal approximations always exist; show that the problem can be solved as a bilinear program; and prove that its threshold problem is in PSPACE and NP-hard. Finally, we present an approach inspired by expectation maximization techniques that provides suboptimal solutions. Experiments suggest that our method gives a practical approach that outperforms the bilinear program implementation run on state-of-the-art bilinear solvers
Nephroblastoma with mucus-producing and argentaffin cells in a pig
Nephroblastoma is the most common primary renal neoplasm of swine and man.
This report describes a swine nephroblastoma localized at the caudal pole of the left
kidney, extending to the renal hilum which, on light microscopy, showed unusual
mucus-producing epithelial cells of many tubules. The presence of intracytoplasmic
mucin was confirmed by PAS-diastase positivity and alcianophilia both at pH 2.5
and at 1.0. Mucin-producing cells revealed cytokeratin 19 and pankeratin AE1/AE3
positivity, and some of them a chromogranin A immunohistochemical positivity;
they were also positive for Grimelius stain. In veterinary medicine, even if the
occurrence of mucus-producing cells in nephroblastoma has rarely been observed,
this is the first description of a case of swine nephroblastoma with mucus-producing
cells positive for neuroendocrine markers, thus a neuroendocrine origin was
suspected
Efficient Local Computation of Differential Bisimulations via Coupling and Up-to Methods
We introduce polynomial couplings, a generalization of probabilistic couplings, to develop an algorithm for the computation of equivalence relations which can be interpreted as a lifting of probabilistic bisimulation to polynomial differential equations, a ubiquitous model of dynamical systems across science and engineering. The algorithm enjoys polynomial time complexity and complements classical partition-refinement approaches because: (a) it implements a local exploration of the system, possibly yielding equivalences that do not necessarily involve the inspection of the whole system of differential equations; (b) it can be enhanced by up-to techniques; and (c) it allows the specification of pairs which ought not be included in the output. Using a prototype, these advantages are demonstrated on case studies from systems biology for applications to model reduction and comparison. Notably, we report four orders of magnitude smaller runtimes than partition-refinement approaches when disproving equivalences between Markov chains
Study of RPC gas mixtures for the ARGO-YBJ experiment
The ARGO-YBJ experiment consists of a RPC carpet to be operated at the
Yangbajing laboratory (Tibet, P.R. China), 4300 m a.s.l., and devoted to the
detection of showers initiated by photon primaries in the energy range 100 GeV
- 20 TeV. The measurement technique, namely the timing on the shower front with
a few tens of particles, requires RPC operation with 1 ns time resolution, low
strip multiplicity, high efficiency and low single counting rate. We have
tested RPCs with many gas mixtures, at sea level, in order to optimize these
parameters. The results of this study are reported.Comment: 6 pages, 3 figures. To be published in Nucl. Instr. Meth. A, talk
given at the "5th International Workshop on RPCs and Related Detectors", Bari
(Italy) 199
- …