251 research outputs found
Applications of Commutator-Type Operators to -Groups
For a p-group G admitting an automorphism of order with exactly
fixed points such that has exactly fixed points,
we prove that G has a fully-invariant subgroup of m-bounded nilpotency class
with -bounded index in G. We also establish its analogue for Lie
p-rings. The proofs make use of the theory of commutator-type operators.Comment: 11 page
Different sensing mechanisms in single wire and mat carbon nanotubes chemical sensors
Chemical sensing properties of single wire and mat form sensor structures
fabricated from the same carbon nanotube (CNT) materials have been compared.
Sensing properties of CNT sensors were evaluated upon electrical response in
the presence of five vapours as acetone, acetic acid, ethanol, toluene, and
water. Diverse behaviour of single wire CNT sensors was found, while the mat
structures showed similar response for all the applied vapours. This indicates
that the sensing mechanism of random CNT networks cannot be interpreted as a
simple summation of the constituting individual CNT effects, but is associated
to another robust phenomenon, localized presumably at CNT-CNT junctions, must
be supposed.Comment: 12 pages, 5 figures,Applied Physics A: Materials Science and
Processing 201
Small amplitude quasi-breathers and oscillons
Quasi-breathers (QB) are time-periodic solutions with weak spatial
localization introduced in G. Fodor et al. in Phys. Rev. D. 74, 124003 (2006).
QB's provide a simple description of oscillons (very long-living spatially
localized time dependent solutions). The small amplitude limit of QB's is
worked out in a large class of scalar theories with a general self-interaction
potential, in spatial dimensions. It is shown that the problem of small
amplitude QB's is reduced to a universal elliptic partial differential
equation. It is also found that there is the critical dimension, ,
above which no small amplitude QB's exist. The QB's obtained this way are shown
to provide very good initial data for oscillons. Thus these QB's provide the
solution of the complicated, nonlinear time dependent problem of small
amplitude oscillons in scalar theories.Comment: 24 pages, 19 figure
Ellipsoidal shapes in general relativity: general definitions and an application
A generalization of the notion of ellipsoids to curved Riemannian spaces is
given and the possibility to use it in describing the shapes of rotating bodies
in general relativity is examined. As an illustrative example, stationary,
axisymmetric perfect-fluid spacetimes with a so-called confocal inside
ellipsoidal symmetry are investigated in detail under the assumption that the
4-velocity of the fluid is parallel to a time-like Killing vector field. A
class of perfect-fluid metrics representing interior NUT-spacetimes is obtained
along with a vacuum solution with a non-zero cosmological constant.Comment: Latex, 22 pages, Revised version accepted in Class. Quantum. Grav.,
references adde
Methodological approach to follow the effectiveness of a hand hygiene peer education training programme at Hungarian schools
Erythema exsudativum multiforme, Stevens-Johnson szindróma és toxikus epidermalis necrolysis provokáló faktorai és klinikai megjelenése
Stringy Robinson-Trautman Solutions
A class of solutions of the low energy string theory in four dimensions is
studied. This class admits a geodesic, shear-free null congruence which is
non-twisting but in general diverging and the corresponding solutions in
Einstein's theory form the Robinson-Trautman family together with a subset of
the Kundt's class. The Robinson-Trautman conditions are found to be frame
invariant in string theory. The Lorentz Chern-Simons three form of the stringy
Robinson-Trautman solutions is shown to be always closed. The stringy
generalizations of the vacuum Robinson-Trautman equation are obtained and three
subclasses of solutions are identified. One of these subclasses exists, among
all the dilatonic theories, only in Einstein's theory and in string theory.
Several known solutions including the dilatonic black holes, the pp- waves, the
stringy C-metric and certain solutions which correspond to exact conformal
field theories are shown to be particular members of the stringy
Robinson-Trautman family. Some new solutions which are static or asymptotically
flat and radiating are also presented. The radiating solutions have a positive
Bondi mass. One of these radiating solutions has the property that it settles
down smoothly to a black hole state at late retarded times.Comment: Latex, 30 Pages, 1 Figure; to appear in Phys. Rev.
Towards a critical theory of communication as renewal and update of Marxist humanism in the age of digital capitalism
This paper's task is to outline some foundations of a critical, Marxist-humanist theory of communication in the age of digital capitalism. It theorises the role of communication in society, communication and alienation, communication in social struggles, social struggles for democratic communication, the contradictions of digital capitalism, and struggles for digital socialist humanism.
Marxist humanism is a counter-narrative, counter-theory, and counter-politics to neoliberalism, new authoritarianism, and postmodernism. A critical theory of communication can should draw on this intellectual tradition. Communication and work stand in a dialectical relationship. Communication mediates, organises and is the process of the production of sociality and therefore of the reproduction of society. Society and communication are in class and capitalist societies shaped by the antagonism between instrumental and co-operative reason. Authoritarianism and humanism are two basic, antagonistic modes of organisation of society and communication. Instrumental reason creates and universalises alienation.
Digital capitalism is a dimension of contemporary society where digital technologies such as the computer, the Internet, the mobile phone, tablets, robots, and AI-driven (“smart”) technologies mediate the accumulation of capital, influence, and reputation. A Marxist-humanist theory of communication aims to inform struggles for a good, commons-based, public Internet in a good, commons-based society that has a vivid, democratic public sphere
Einstein's fluctuation formula. A historical overview
A historical overview is given on the basic results which appeared by the
year 1926 concerning Einstein's fluctuation formula of black-body radiation, in
the context of light-quanta and wave-particle duality. On the basis of the
original publications (from Planck's derivation of the black-body spectrum and
Einstein's introduction of the photons up to the results of Born, Heisenberg
and Jordan on the quantization of a continuum) a comparative study is presented
on the first line of thoughts that led to the concept of quanta. The nature of
the particle-like fluctuations and the wave-like fluctuations are analysed by
using several approaches. With the help of the classical probability theory, it
is shown that the infinite divisibility of the Bose distribution leads to the
new concept of classical poissonian photo-multiplets or to the binary
photo-multiplets of fermionic character. As an application, Einstein's
fluctuation formula is derived as a sum of fermion type fluctuations of the
binary photo-multiplets.Comment: 34 page
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