219 research outputs found
The algebra of adjacency patterns: Rees matrix semigroups with reversion
We establish a surprisingly close relationship between universal Horn classes
of directed graphs and varieties generated by so-called adjacency semigroups
which are Rees matrix semigroups over the trivial group with the unary
operation of reversion. In particular, the lattice of subvarieties of the
variety generated by adjacency semigroups that are regular unary semigroups is
essentially the same as the lattice of universal Horn classes of reflexive
directed graphs. A number of examples follow, including a limit variety of
regular unary semigroups and finite unary semigroups with NP-hard variety
membership problems.Comment: 30 pages, 9 figure
A classification of bisymmetric polynomial functions over integral domains of characteristic zero
We describe the class of n-variable polynomial functions that satisfy
Acz\'el's bisymmetry property over an arbitrary integral domain of
characteristic zero with identity
Optimal discrimination of mixed quantum states involving inconclusive results
We propose a generalized discrimination scheme for mixed quantum states. In
the present scenario we allow for certain fixed fraction of inconclusive
results and we maximize the success rate of the quantum-state discrimination.
This protocol interpolates between the Ivanovic-Dieks-Peres scheme and the
Helstrom one. We formulate the extremal equations for the optimal positive
operator valued measure describing the discrimination device and establish a
criterion for its optimality. We also devise a numerical method for efficient
solving of these extremal equations.Comment: 5 pages, 1 figur
Minimax mean estimator for the trine
We explore the question of state estimation for a qubit restricted to the
- plane of the Bloch sphere, with the trine measurement. In our earlier
work [H. K. Ng and B.-G. Englert, eprint arXiv:1202.5136[quant-ph] (2012)],
similarities between quantum tomography and the tomography of a classical die
motivated us to apply a simple modification of the classical estimator for use
in the quantum problem. This worked very well. In this article, we adapt a
different aspect of the classical estimator to the quantum problem. In
particular, we investigate the mean estimator, where the mean is taken with a
weight function identical to that in the classical estimator but now with
quantum constraints imposed. Among such mean estimators, we choose an optimal
one with the smallest worst-case error-the minimax mean estimator-and compare
its performance with that of other estimators. Despite the natural
generalization of the classical approach, this minimax mean estimator does not
work as well as one might expect from the analogous performance in the
classical problem. While it outperforms the often-used maximum-likelihood
estimator in having a smaller worst-case error, the advantage is not
significant enough to justify the more complicated procedure required to
construct it. The much simpler adapted estimator introduced in our earlier work
is still more effective. Our previous work emphasized the similarities between
classical and quantum state estimation; in contrast, this paper highlights how
intuition gained from classical problems can sometimes fail in the quantum
arena.Comment: 18 pages, 3 figure
Post-processing the results of the topology optimization with the level-set technique
The work was supported by the Technology Agency of the Czech Republic under grant No
TN01000024/08 (National Competence Center-Cybernetics and Artificial Intelligence) – sub-
project “Automation and production system optimization” within institutional support
RVO:61388998 and by the Grant Agency of the Czech Technical University in Prague, under
grant No. SGS21/151/OHK2/3T/12
The Development of Blood and Lymph Vessels of Human Parathyroid Glands in Embryonal, Fetal and Postnatal Period
The aim of the article is to investigate the development of blood and lymph systems in
human parathyroid glands in prenatal and postnatal periods. The first capillaries are
observed in these glands already in the lunar month 2. At the middle of pregnancy blood
supply is increased, being extremely abundant in lunar months 9 and 10, as well as
during the first year of life. As parts of the lymph system, intercellular lymph spaces are
noticed in the parathyroid glands already in the lunar month 2, and also later, when
lymph vessels are situated along the gland or in its connective capsule and within the
gland parenchyma respectively. All these findings could be connected with the early
function of these glands, as well as with the possibility that parathyroid hormone (PTH)
is not transferred by blood only but by lymph as well
Lung Lavage Neutrophils, Neutrophil Elastase and Albumin in the Prognosis of Pulmonary Sarcoidosis
The authors measured the bronchoalveolar lavage fluid (BALF) neutrophils, neutrophil
elastase and albumin in 60 patients with pulmonary sarcoidosis, 18 patients
with other interstitial lung diseases and 14 healthy controls in order to evaluate its significance
in the prognosis of sarcoidosis. The concentrations were measured by enzymoimmunoassay
and radial immunodiffusion (LC plates). Obtained values were correlated
with some clinical indices, radiological stage and lung function values. The
patients were followed up for 22.3 6.8 months. At the end of observation period the
outcome of sarcoidosis has been evaluated upon the findings of chest radiograms and
lung function tests. The length of duration of the disease correlated with the lung lavage
neutrophil counts (r = 0.2535; p < 0.05). Significantly higher values of BALF elastase
were obtained in III radiologic stage than II and I. Patients with high BALF albumin
had more often dispnoa (p < 0.05) and chronic forms of the disease (p < 0.05). The values
were high in patients in II and III radiologic stage. Unfavorable outcome of chest radiograms
was announced by high BALF albumins (p < 0.05). The measurement of
BALF neutrophils, neutrophil elastase and albumin are helpful in clinical management
and estimation of the prognosis in patients with pulmonary sarcoidosis
- …