960 research outputs found
Allen Linear (Interval) Temporal Logic --Translation to LTL and Monitor Synthesis--
The relationship between two well established formalisms for temporal reasoning is first investigated, namely between Allen's interval algebra (or Allen's temporal logic, abbreviated \ATL) and linear temporal logic (\LTL). A discrete variant of \ATL is defined, called Allen linear temporal logic (\ALTL), whose models are \omega-sequences of timepoints, like in \LTL. It is shown that any \ALTL formula can be linearly translated into an equivalent \LTL formula, thus enabling the use of \LTL techniques and tools when requirements are expressed in \ALTL. %This translation also implies the NP-completeness of \ATL satisfiability. Then the monitoring problem for \ALTL is discussed, showing that it is NP-complete despite the fact that the similar problem for \LTL is EXPSPACE-complete. An effective monitoring algorithm for \ALTL is given, which has been implemented and experimented with in the context of planning applications
A preliminary “least cost” study of future groundwater development in northeastern Illinois
Cover title.Includes bibliographical references (p. 19)
Relativistic two-body equation based on the extension of the SL(2,C) group
A new approach to the two-body problem based on the extension of the
group to the one is developed. The wave equation with
various forms of including the interaction for the system of the spin-1/2 and
spin-0 particles is constructed. For this system, it was found that the wave
equation with a linear confinement potential involved in the non-minimal manner
has an oscillator-like form and possesses the exact solution.Comment: 9 pages, no figure
Special relativity constraints on the effective constituent theory of hybrids
We consider a simplified constituent model for relativistic
strong-interaction decays of hybrid mesons. The model is constructed using
rules of renormalization group procedure for effective particles in light-front
quantum field theory, which enables us to introduce low-energy phenomenological
parameters. Boost covariance is kinematical and special relativity constraints
are reduced to the requirements of rotational symmetry. For a hybrid meson
decaying into two mesons through dissociation of a constituent gluon into a
quark-anti-quark pair, the simplified constituent model leads to a rotationally
symmetric decay amplitude if the hybrid meson state is made of a constituent
gluon and a quark-anti-quark pair of size several times smaller than the
distance between the gluon and the pair, as if the pair originated from one
gluon in a gluonium state in the same effective theory.Comment: 11 pages, 5 figure
Interactions for odd-omega gap singlet superconductors
A class of singlet superconductors with a gap function which is {\it odd} in both momentum and Matsubara frequency was
proposed recently \cite{ba}. To show an instability in the {\it odd} gap
channel, a model phonon propagator was used with the -wave interaction
strength larger than the -wave. We argue that the positive scattering matrix
element entering the Eliashberg equations leads to a constraint on the relative
strength of - and -wave interactions which inhibits odd pairing. However,
a general spin dependent electron-electron interaction can satisfy all
constraints and produce the odd singlet gap. A possibility which may lead to an
odd gap is a strongly antiferromagnetically correlated system, such as a
high- material.Comment: This paper corrects some errors (including the omission of one of the
authors) in the original 9206003 and also a minor error in the published
version, Phys. Rev. B {\bf 47}, 513 (1993). It also contains some comments on
subsequent claims of the impossibility of odd-frequency pairing. Latex fil
Phonons and specific heat of linear dense phases of atoms physisorbed in the grooves of carbon nanotube bundles
The vibrational properties (phonons) of a one-dimensional periodic phase of
atoms physisorbed in the external groove of the carbon nanotube bundle are
studied. Analytical expressions for the phonon dispersion relations are
derived. The derived expressions are applied to Xe, Kr and Ar adsorbates. The
specific heat pertaining to dense phases of these adsorbates is calculated.Comment: 4 PS figure
Progress and challenges in the understanding of chronic urticaria
Chronic urticaria is a skin disorder characterized by transient pruritic weals that recur from day to day for 6 weeks or more. It has a great impact on patients' quality of life. In spite of this prevalence and morbidity, we are only beginning to understand its physiopathology and we do not have a curative treatment. Moreover, a patient with chronic urticaria may undergo extensive laboratory evaluations seeking a cause only to be frustrated when none is found. In recent years there have been significant advances in our understanding of some of the molecular mechanisms responsible for hive formation. The presence and probable role of IgG autoantibodies directed against epitopes expressed on the alpha-chain of the IgE receptor and to lesser extent, to IgE in a subset of patients is generally acknowledged. These autoantibodies activate complement to release C5a, which augments histamine release, and IL4 and leukotriene C4 are released as well. A perivascular cellular infiltrate results without predominance of either Th1 or Th2 lymphocyte subpopulations. Basophils of all chronic urticaria patients (autoimmune or idiopathic) are hyperresponsive to serum, regardless of source, but poorly responsive to anti IgE. In this review we will summarize the recent contributions to this field and try to provide insights to possible future directions for research on this disease
The superconducting phase of Calcium under the pressure at 200 GPa: the strong-coupling description
The thermodynamic parameters of the superconducting state in Calcium under
the pressure at 200 GPa have been determined. The numerical analysis by using
the Eliashberg equations in the mixed representation has been conducted. It has
been stated, that the critical temperature () decreases from 36.15 K to
20.79 K dependently on the assumed value of the Coulomb pseudopotential
(). Next, the order parameter near the temperature of zero
Kelvin () has been obtained. It has been proven, that the
dimensionless ratio decreases from 4.25 to 3.90
together with the growth of . Finally, the ratio of the electron
effective mass to the electron bare mass () has been
calculated. It has been shown, that takes the high value in
the whole range of the superconducting phase's existence, and its maximum is
equal to 2.23 for T=T_{C}.Comment: 5 pages, 5 figure
The price of rapid exit in venture capital-backed IPOs
This paper proposes an explanation for two empirical puzzles surrounding initial public offerings (IPOs). Firstly, it is well documented that IPO underpricing increases during “hot issue” periods. Secondly, venture capital (VC) backed IPOs are less underpriced than non-venture capital backed IPOs during normal periods of activity, but the reverse is true during hot issue periods: VC backed IPOs are more underpriced than non-VC backed ones. This paper shows that when IPOs are driven by the initial investor’s desire to exit from an existing investment in order to finance a new venture, both the value of the new venture and the value of the existing firm to be sold in the IPO drive the investor’s choice of price and fraction of shares sold in the IPO. When this is the case, the availability of attractive new ventures increases equilibrium underpricing, which is what we observe during hot issue periods. Moreover, I show that underpricing is affected by the severity of the moral hazard problem between an investor and the firm’s manager. In the presence of a moral hazard problem the degree of equilibrium underpricing is more sensitive to changes in the value of the new venture. This can explain why venture capitalists, who often finance firms with more severe moral hazard problems, underprice IPOs less in normal periods, but underprice more strongly during hot issue periods. Further empirical implications relating the fraction of shares sold and the degree of underpricing are presented
Crystallization of a classical two-dimensional electron system: Positional and orientational orders
Crystallization of a classical two-dimensional one-component plasma
(electrons interacting with the Coulomb repulsion in a uniform neutralizing
positive background) is investigated with a molecular dynamics simulation. The
positional and the orientational correlation functions are calculated for the
first time. We have found an indication that the solid phase has a
quasi-long-range (power-law) positional order along with a long-range
orientational order. This indicates that, although the long-range Coulomb
interaction is outside the scope of Mermin's theorem, the absence of ordinary
crystalline order at finite temperatures applies to the electron system as
well. The `hexatic' phase, which is predicted between the liquid and the solid
phases by the Kosterlitz-Thouless-Halperin-Nelson-Young theory, is also
discussed.Comment: 3 pages, 4 figures; Corrected typos; Double columne
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