199 research outputs found
The Development of Transport in the Czech Republic
Before 1989, transport in the former Czechoslovakia met its tasks based on the controlling principles of
planned economy, focused eastwards and oriented on cooperation between the Eastern Bloc countries
within COMECOM. Due to the preference for raw material extraction and heavy industry, the transport
sector dealt mainly with transporting commodities of these branches with high demands in volume. The
planned economic principles were also reflected by the consistent division of transport work with a
preference for stack substrate transport by rail.
The change of the political and economic circumstances in November 1989 influenced the life and
needs of society substantially. A market economy has come, focused on the market of developed
European countries and having an impact on the transport sector as such, individual transport systems,
transport preferences and transported commodities [2].
As at 1 January 1993, Czechoslovakia has been divided into two independent countries, i.e. the Czech
Republic and Slovakia. Therefore the following data from the Transport Statistics of the Czech Republic
[1] are comparable starting from 1994. The authors of the article had data available until 2006
Fitting the grain orientation distribution of a polycrystalline material conditioned on a Laguerre tessellation
The description of distributions related to grain microstructure helps
physicists to understand the processes in materials and their properties. This
paper presents a general statistical methodology for the analysis of
crystallographic orientations of grains in a 3D Laguerre tessellation dataset
which represents the microstructure of a polycrystalline material. We introduce
complex stochastic models which may substitute expensive laboratory
experiments: conditional on the Laguerre tessellation, we suggest interaction
models for the distribution of cubic crystal lattice orientations, where the
interaction is between pairs of orientations for neighbouring grains in the
tessellation. We discuss parameter estimation and model comparison methods
based on maximum pseudolikelihood as well as graphical procedures for model
checking using simulations. Our methodology is applied for analysing a dataset
representing a nickel-titanium shape memory alloy
Quantum Circuits for the Unitary Permutation Problem
We consider the Unitary Permutation problem which consists, given unitary
gates and a permutation of , in
applying the unitary gates in the order specified by , i.e. in
performing . This problem has been
introduced and investigated by Colnaghi et al. where two models of computations
are considered. This first is the (standard) model of query complexity: the
complexity measure is the number of calls to any of the unitary gates in
a quantum circuit which solves the problem. The second model provides quantum
switches and treats unitary transformations as inputs of second order. In that
case the complexity measure is the number of quantum switches. In their paper,
Colnaghi et al. have shown that the problem can be solved within calls in
the query model and quantum switches in the new model. We
refine these results by proving that quantum switches
are necessary and sufficient to solve this problem, whereas calls
are sufficient to solve this problem in the standard quantum circuit model. We
prove, with an additional assumption on the family of gates used in the
circuits, that queries are required, for any
. The upper and lower bounds for the standard quantum circuit
model are established by pointing out connections with the permutation as
substring problem introduced by Karp.Comment: 8 pages, 5 figure
Decorrelation of a class of Gibbs particle processes and asymptotic properties of U-statistics
We study a stationary Gibbs particle process with deterministically bounded particles on
Euclidean space defined in terms of an activity parameter and non-negative interaction
potentials of finite range. Using disagreement percolation we prove exponential decay of
the correlation functions, provided a dominating Boolean model is subcritical. We also
prove this property for the weighted moments of a U-statistic of the process. Under the
assumption of a suitable lower bound on the variance, this implies a central limit theorem
for such U-statistics of the Gibbs particle process. A byproduct of our approach is a new
uniqueness result for Gibbs particle processes
Beta3 adrenoceptors substitute the role of M 2 muscarinic receptor in coping with cold stress in the heart: Evidence from M 2KO mice
We investigated the role of beta3-adrenoceptors (AR) in cold stress (1 or 7 days in cold) in animals lacking main cardioinhibitive receptors - M2 muscarinic receptors (M 2KO). There was no change in receptor number in the right ventricles. In the left ventricles, there was decrease in binding to all cardiostimulative receptors (beta1-, and beta2-AR) and increase in cardiodepressive receptors (beta3-AR) in unstressed KO in comparison to WT. The cold stress in WT animals resulted in decrease in binding to beta1- and beta2-AR (to 37%/35% after 1 day in cold and to 27%/28% after 7 days in cold) while beta3-AR were increased (to 216% of control) when 7 days cold was applied. MR were reduced to 46% and 58%, respectively. Gene expression of M2 MR in WT was not changed due to stress, while M3 was changed. The reaction of beta1- and beta2-AR (binding) to cold was similar in KO and WT animals, and beta3-AR in stressed KO animals did not change. Adenylyl cyclase activity was affected by beta3-agonist CL316243 in cold stressed WT animals but CL316243 had almost no effects on adenylyl cyclase activity in stressed KO. Nitric oxide activity (NOS) was not affected by BRL37344 (beta3-agonist) both in WT and KO animals. Similarly, the stress had no effects on NOS activity in WT animals and in KO animals. We conclude that the function of M2 MR is substituted by beta3-AR and that these effects are mediated via adenylyl cyclase rather than NOS. © Springer Science+Business Media, LLC 2011
Development of proglacial lakes and evaluation of related outburst susceptibility at the Adygine ice-debris complex, northern Tien Shan
The formation and development of glacial lakes in mountainous
regions is one of the consequences of glacier recession. Such lakes may drain
partially or completely when the stability of their dams is disturbed or as
a consequence of impacts. We present a case study from the Central Asian
mountain range of Tien Shan – a north-oriented tributary of the Adygine
Valley, where the retreat of a polythermal glacier surrounded by permafrost
has resulted in the formation of several generations of lakes. The aim of
this study was to analyse the past development of different types of glacial
lakes influenced by the same glacier, to project the site's future
development, and to evaluate the outburst susceptibility of individual lakes
with an outlook for expected future change. We addressed the problem using a
combination of methods, namely bathymetric, geodetic and geophysical on-site
surveys, satellite images and digital elevation model analysis, and modelling
of glacier development. Based on this case of the glacial lakes being of
varied age and type, we demonstrated the significance of glacier ice in lake
development. Lake 3, which is in contact with the glacier terminus, has
changed rapidly over the last decade, expanding both in area and depth and
increasing its volume by more than 13 times (7800 to 106 000 m3). The hydrological connections and routing of glacier meltwater have
proved to be an important factor as well, since most lakes in the region are
drained by subsurface channels. As the site is at the boundary between
continuous and discontinuous permafrost, the subsurface water flow is
strongly governed by the distribution of non-frozen zones above, within, or
beneath the perennially frozen ground. In the evaluation of lake outburst
susceptibility, we have highlighted the importance of field data, which can
provide crucial information on lake stability. In our case, an understanding
of the hydrological system at the site, and its regime, helped to categorise
Lake 2 as having low outburst susceptibility, while Lake 1 and Lake 3 were labelled as
lakes with medium outburst susceptibility. Further development of the site
will be driven mainly by rising air temperatures and increasingly negative
glacier mass balance. All three climate model scenarios predicted a
significant glacier areal decrease by 2050, specifically leaving 73.2 %
(A1B), 62.3 % (A2), and 55.6 % (B1) of the extent of the glacier in 2012.
The glacier retreat will be accompanied by changes in glacier runoff, with
the first peak expected around 2020, and the formation of additional lakes.</p
- …