16,638 research outputs found
Synchronization of oscillators with long range power law interactions
We present analytical calculations and numerical simulations for the
synchronization of oscillators interacting via a long range power law
interaction on a one dimensional lattice. We have identified the critical value
of the power law exponent across which a transition from a
synchronized to an unsynchronized state takes place for a sufficiently strong
but finite coupling strength in the large system limit. We find .
Frequency entrainment and phase ordering are discussed as a function of . The calculations are performed using an expansion about the aligned
phase state (spin-wave approximation) and a coarse graining approach. We also
generalize the spin-wave results to the {\it d}-dimensional problem.Comment: Final published versio
Steady-states and kinetics of ordering in bus-route models: connection with the Nagel-Schreckenberg model
A Bus Route Model (BRM) can be defined on a one-dimensional lattice, where
buses are represented by "particles" that are driven forward from one site to
the next with each site representing a bus stop. We replace the random
sequential updating rules in an earlier BRM by parallel updating rules. In
order to elucidate the connection between the BRM with parallel updating
(BRMPU) and the Nagel-Schreckenberg (NaSch) model, we propose two alternative
extensions of the NaSch model with space-/time-dependent hopping rates.
Approximating the BRMPU as a generalization of the NaSch model, we calculate
analytically the steady-state distribution of the {\it time headways} (TH)
which are defined as the time intervals between the departures (or arrivals) of
two successive particles (i.e., buses) recorded by a detector placed at a fixed
site (i.e., bus stop) on the model route. We compare these TH distributions
with the corresponding results of our computer simulations of the BRMPU, as
well as with the data from the simulation of the two extended NaSch models. We
also investigate interesting kinetic properties exhibited by the BRMPU during
its time evolution from random initial states towards its steady-states.Comment: Accepted for publication in EPJ
Money Demand Stability under Currency Substitution: Some Recent Evidence
This study deals with the issue of independent monetary policy and the stability of the domestic money demand function in the presence of currency substitution and capital mobility in five Asian economies. It is argued that money demand will be less stable and more difficult to control in the presence of international variables. The money demand function is derived using the portfolio balance approach. The results from the cointegration analysis reveal that capital mobility and currency substitution are significant factors in the domestic money demand equations for Indonesia, Korea, Malaysia, Singapore, and Thailand. The results also show that the US dollar, Japanese yen, and British pound are used significantly by domestic residents together with the domestic currency in Indonesia, Korea, Singapore and Thailand. However, in the case of Malaysia, despite the existence of currency substitution for the US dollar and Japanese yen, there is no evidence of currency substitution between the domestic currency and British pound. Therefore, for these countries to have an effective monetary policy, the monetary authorities should take into account the two international factors
Lambda hyperonic effect on the normal driplines
A generalized mass formula is used to calculate the neutron and proton drip
lines of normal and lambda hypernuclei treating non-strange and strange nuclei
on the same footing. Calculations suggest existence of several bound
hypernuclei whose normal cores are unbound. Addition of Lambda or,
Lambda-Lambda hyperon(s) to a normal nucleus is found to cause shifts of the
neutron and proton driplines from their conventional limits.Comment: 6 pages, 4 tables, 0 figur
A Mass Formula from Light to Hypernuclei
Simultaneous description of ordinary and hypernuclei masses by a single mass
formula has been a great challenge in nuclear physics. Hyperon-separation
energies of about forty Lambda(), three
Lambda-Lambda(), one Sigma() and seven Cascade()
hypernuclei have been experimentally found. Many of these nuclei are of light
masses. We prescribe a new mass formula, called BWMH, which describes the
normal and hypernuclei on the same footing. It is based on the
modified-Bethe-Weizs\"acker mass formula (BWM). BWM is basically an extension
of the Bethe-Weizs\"acker mass formula (BW) for light nuclei. The parameters of
BWM were optimized by fitting about 3000 normal nuclei available recently. The
original Bethe-Weizs\"acker mass formula (BW) was designed for medium and heavy
mass nuclei and it fails for light nuclei. Two earlier works on hypernuclei
based on this BW show some limitations. The BWMH gives improved agreement with
the experimental data for the line of stability, one-neutron separation energy
versus neutron number spectra of normal nuclei, and the hyperon-separation
energies from hypernuclei. The drip lines are modified for addition of a
hyperon in a normal nucleus.Comment: Presented at the "XXIX Mazurian Lakes Conference on Physics: Nuclear
Physics and the Fundamental Processes, Piaski, Poland, August 30 - September
6, 2005." (7 pages, 1 Table, 1 Figure
The Slowdown in Soviet Defense Expenditures: Comment
The reason for the apparently opposing results in Brada and Graves\u27 (1988) attempt to explain the reasons for the slowdown in USSR defense expenditures in the mid-1970s is that their analysis suffers from a serious serial correlation problem. The majority of the regressions display Durbin-Watson statistics that reject the null hypothesis of no autocorrelation. A reestimation of their results, after correcting for serial correlation, changes some of their major conclusions regarding the factors influencing Soviet defense spending. The corrected results indicate that no structural break occurred in the mid-1970s. These results suggest that there has been no change in Soviet military doctrine or in the Soviet leadership\u27s preferences in the 1970s. In reply, Brada and Graves argue that the evidence for the existence of serially correlated disturbances is much more tenuous than Chowdhury suggests and that the evidence is more consistent with the existence of a structural break and no serial correlation of disturbances
Isobaric incompressibility of the isospin asymmetric nuclear matter
The isospin dependence of the saturation properties of asymmetric nuclear
matter, particularly the incompressibility at saturation density is systematically studied using density
dependent M3Y interaction. The characterizes the isospin dependence of
the incompressibility at saturation density . The approximate
expression is often used for where
and represent, respectively, the slope and curvature parameters of
the symmetry energy at . It can be expressed accurately as
where is the third-order
derivative parameter of symmetric nuclear matter at . The results of
this addendum to Phys. Rev. C 80, 011305(R) (2009) indicate that the
contribution to is not insignificant.Comment: 4 pages including 1 table and 1 figur
The Slowdown in Soviet Defense Expenditures: Comment
The reason for the apparently opposing results in Brada and Graves\u27 (1988) attempt to explain the reasons for the slowdown in USSR defense expenditures in the mid-1970s is that their analysis suffers from a serious serial correlation problem. The majority of the regressions display Durbin-Watson statistics that reject the null hypothesis of no autocorrelation. A reestimation of their results, after correcting for serial correlation, changes some of their major conclusions regarding the factors influencing Soviet defense spending. The corrected results indicate that no structural break occurred in the mid-1970s. These results suggest that there has been no change in Soviet military doctrine or in the Soviet leadership\u27s preferences in the 1970s. In reply, Brada and Graves argue that the evidence for the existence of serially correlated disturbances is much more tenuous than Chowdhury suggests and that the evidence is more consistent with the existence of a structural break and no serial correlation of disturbances
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