2,057 research outputs found
Passivity-Based Control of Human-Robotic Networks with Inter-Robot Communication Delays and Experimental Verification
In this paper, we present experimental studies on a cooperative control
system for human-robotic networks with inter-robot communication delays. We
first design a cooperative controller to be implemented on each robot so that
their motion are synchronized to a reference motion desired by a human
operator, and then point out that each robot motion ensures passivity.
Inter-robot communication channels are then designed via so-called scattering
transformation which is a technique to passify the delayed channel. The
resulting robotic network is then connected with human operator based on
passivity theory. In order to demonstrate the present control architecture, we
build an experimental testbed consisting of multiple robots and a tablet. In
particular, we analyze the effects of the communication delays on the human
operator's behavior
Tensor mesons produced in tau lepton decays
Light tensor mesons (T = a_2, f_2 and K_2^*) can be produced in decays of tau
leptons. In this paper we compute the branching ratios of tau --> T pi nu
decays by assuming the dominance of intermediate virtual states to model the
form factors involved in the relevant hadronic matrix element. The exclusive
f_2(1270) pi^- decay mode turns out to have the largest branching ratio, of
O(10^-4) . Our results indicate that the contributions of tensor meson
intermediate states to the three-pseudoscalar channels of tau decays are rather
small.Comment: 10 pages, 1 figure. Version accepted for publication in PRD, some
typos are corrected and comments are added in section 4. Conclusions remain
unchange
The Gauge Hierarchy Problem and Higher Dimensional Gauge Theories
We report on an attempt to solve the gauge hierarchy problem in the framework
of higher dimensional gauge theories. Both classical Higgs mass and
quadratically divergent quantum correction to the mass are argued to vanish.
Hence the hierarchy problem in its original sense is solved. The remaining
finite mass correction is shown to depend crucially on the choice of boundary
condition for matter fields, and a way to fix it dynamically is presented. We
also point out that on the simply-connected space even the finite mass
correction vanishes.Comment: LaTeX2e. 12 pages, 3 Postscript figures; Added references, some
comment
Radiative and Semileptonic B Decays Involving Higher K-Resonances in the Final States
We study the radiative and semileptonic B decays involving a spin-
resonant with parity for and for
in the final state. Using the large energy effective theory (LEET)
techniques, we formulate transition form factors in the large
recoil region in terms of two independent LEET functions
and , the values of
which at zero momentum transfer are estimated in the BSW model. According to
the QCD counting rules, exhibit a dipole
dependence in . We predict the decay rates for ,
and . The
branching fractions for these decays with higher -resonances in the final
state are suppressed due to the smaller phase spaces and the smaller values of
. Furthermore, if the spin of
becomes larger, the branching fractions will be further suppressed due to the
smaller Clebsch-Gordan coefficients defined by the polarization tensors of the
. We also calculate the forward backward asymmetry of the decay, for which the zero is highly insensitive to the
-resonances in the LEET parametrization.Comment: 27 pages, 4 figures, 7 tables;contents and figures corrected, title
and references revise
Five steps in leukocyte extravasation in the microcirculation by chemoattractants
For in vivo study of the phenomena observed in vitro, PMN (polymorphonuclear leukocyte) extravasation was analysed quantitatively in the microcirculation of the hamster cheek pouch using a video system. Topical application of leukotriene B4 or N-formyl-methionylleucyl- phenylalanine increased dose dependently the number of PMNs adhering to the venules. Eighty to 90% of the adhering PMNs disappeared from the vascular lumen into the venular wall within 10-12 rain after the adhesion. After PMNs had passed through the endothelial cell layer, they remained in the venular wall for more than 30 min after application of the chemoattractants and appeared in the extravascular space. Thus, the process could be divided into five steps: (1) rolling and (2) adhesion to the endothelium, (3) passage through the endothelial layer (4) remaining in the venular wall, and (5) passage through the basement membrane
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