114 research outputs found
A Complete Axiom System for Propositional Interval Temporal Logic with Infinite Time
Interval Temporal Logic (ITL) is an established temporal formalism for
reasoning about time periods. For over 25 years, it has been applied in a
number of ways and several ITL variants, axiom systems and tools have been
investigated. We solve the longstanding open problem of finding a complete
axiom system for basic quantifier-free propositional ITL (PITL) with infinite
time for analysing nonterminating computational systems. Our completeness proof
uses a reduction to completeness for PITL with finite time and conventional
propositional linear-time temporal logic. Unlike completeness proofs of equally
expressive logics with nonelementary computational complexity, our semantic
approach does not use tableaux, subformula closures or explicit deductions
involving encodings of omega automata and nontrivial techniques for
complementing them. We believe that our result also provides evidence of the
naturalness of interval-based reasoning
A timeband framework for modelling real-time systems
Complex real-time systems must integrate physical processes with digital control, human operation and organisational structures. New scientific foundations are required for specifying, designing and implementing these systems. One key challenge is to cope with the wide range of time scales and dynamics inherent in such systems. To exploit the unique properties of time, with the aim of producing more dependable computer-based systems, it is desirable to explicitly identify distinct time bands in which the system is situated. Such a framework enables the temporal properties and associated dynamic behaviour of existing systems to be described and the requirements for new or modified systems to be specified. A system model based on a finite set of distinct time bands is motivated and developed in this paper
Borromean Binding of Three or Four Bosons
We estimate the ratio of the critical coupling constants
and which are required to achieve binding of 2 or 3 bosons,
respectively, with a short-range interaction, and examine how this ratio
depends on the shape of the potential. Simple monotonous potentials give
. A wide repulsive core pushes this ratio close to R=1. On the
other hand, for an attractive well protected by an external repulsive barrier,
the ratio approaches the rigorous lower bound . We also present results
for N=4 bosons, sketch the extension to , and discuss various
consequences.Comment: 12 pages, RevTeX, 5 Figures in tex include
Moments of Inertia of Nuclei in the Rare Earth Region: A Relativistic versus Non-Relativistic Investigation
A parameter free investigation of the moments of inertia of ground state
rotational bands in well deformed rare-earth nuclei is carried out using
Cranked Relativistic Hartree-Bogoliubov (CRHB) and non-relativistic Cranked
Hartree-Fock-Bogoliubov (CHFB) theories. In CRHB theory, the relativistic
fields are determined by the non-linear Lagrangian with the NL1 force and the
pairing interaction by the central part of finite range Gogny D1S force. In
CHFB theory, the properties in particle-hole and particle-particle channels are
defined solely by Gogny D1S forces. Using an approximate particle number
projection before variation by means of the Lipkin Nogami method improves the
agreement with the experimental data, especially in CRHB theory. The effect of
the particle number projection on the moments of inertia and pairing energies
is larger in relativistic than in non-relativistic theory.Comment: 18 pages + 2 PostScript figure
Relativistic quantum transport theory of hadronic matter: the coupled nucleon, delta and pion system
We derive the relativistic quantum transport equation for the pion
distribution function based on an effective Lagrangian of the QHD-II model. The
closed time-path Green's function technique, the semi-classical, quasi-particle
and Born approximation are employed in the derivation. Both the mean field and
collision term are derived from the same Lagrangian and presented analytically.
The dynamical equation for the pions is consistent with that for the nucleons
and deltas which we developed before. Thus, we obtain a relativistic transport
model which describes the hadronic matter with , and degrees
of freedom simultaneously. Within this approach, we investigate the medium
effects on the pion dispersion relation as well as the pion absorption and pion
production channels in cold nuclear matter. In contrast to the results of the
non-relativistic model, the pion dispersion relation becomes harder at low
momenta and softer at high momenta as compared to the free one, which is mainly
caused by the relativistic kinetics. The theoretically predicted free cross section is in agreement with the experimental data. Medium
effects on the cross section and momentum-dependent
-decay width are shown to be substantial.Comment: 66 pages, Latex, 12 PostScript figures included; replaced by the
revised version, to appear in Phys. Rev.
Somatosensory processing in neurodevelopmental disorders
The purpose of this article is to review the role of somatosensory perception in typical development, its aberration in a range of neurodevelopmental disorders, and the potential relations between tactile processing abnormalities and central features of each disorder such as motor, communication, and social development. Neurodevelopmental disorders that represent a range of symptoms and etiologies, and for which multiple peer-reviewed articles on somatosensory differences have been published, were chosen to include in the review. Relevant studies in animal models, as well as conditions of early sensory deprivation, are also included. Somatosensory processing plays an important, yet often overlooked, role in typical development and is aberrant in various neurodevelopmental disorders. This is demonstrated in studies of behavior, sensory thresholds, neuroanatomy, and neurophysiology in samples of children with Fragile X syndrome, autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD), and cerebral palsy (CP). Impaired somatosensory processing is found in a range of neurodevelopmental disorders and is associated with deficits in communication, motor ability, and social skills in these disorders. Given the central role of touch in early development, both experimental and clinical approaches should take into consideration the role of somatosensory processing in the etiology and treatment of neurodevelopmental disorders
Developmental perspectives on interpersonal affective touch
In the last decade, philosophy, neuroscience and psychology alike have paid increasing attention to the study of interpersonal affective touch, which refers to the emotional and motivational facets of tactile sensation. Some aspects of affective touch have been linked to a neurophysiologically specialised system, namely the C tactile (CT) system. While the role of this sys-tem for affiliation, social bonding and communication of emotions have been widely investigated, only recently researchers have started to focus on the potential role of interpersonal affective touch in acquiring awareness of the body as our own, i.e. as belonging to our psychological ‘self’. We review and discuss recent developmental and adult findings, pointing to the central role of interpersonal affective touch in body awareness and social cognition in health and disorders. We propose that interpersonal affective touch, as an interoceptive modality invested of a social nature, can uniquely contribute to the ongoing debate in philosophy about the primacy of the relational nature of the minimal self
Relativistic transport theory of N, \Delta and N^{*}(1440) interacting through , and mesons
A self-consistent relativistic integral-differential equation of the
Boltzmann-Uehling-Uhlenbeck-type for the (1440) resonance is developed
based on an effective Lagrangian of baryons interacting through mesons. The
closed time-path Green's function technique and semi-classical, quasi-particle
and Born approximations are employed in the derivation. The non-equilibrium
RBUU-type equation for the (1440) is consistent with that of nucleon's
and delta's which we derived before. Thus, we obtain a set of coupled equations
for the , and (1440) distribution functions.
All the (1440)-relevant in-medium two-body scattering cross sections
within the , and (1440) system are derived from the same
effective Lagrangian in addition to the mean field and presented analytically,
which can be directly used in the study of relativistic heavy-ion collisions.
The theoretical prediction of the free cross section is
in good agreement with the experimental data. We calculate the in-medium , and cross
sections in cold nuclear matter up to twice the nuclear matter density. The
influence of different choices of the coupling strengths, which
can not be obtained through fitting certain experimental data, are discussed.
The results show that the density dependence of predicted in-medium cross
sections are sensitive to the coupling strengths used. An evident
density dependence will appear when a large scalar coupling strength of
is assumed.Comment: 64 pages, Latex, 13 PostScript figures include
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