197,731 research outputs found
Applying the Hirose-Kamada filter to Swiss data: Output gap and exchange rate pass-through estimates
No full textMultivariate filters based on the Hodrick-Prescott filter are appealing because they combine the advantages of the Hodrick-Prescott filter with economic relationships. Recently, a new multivariate filter has been put forward by Hirose and Kamada (2003). In this article we apply this new filter to Swiss data spanning the period from 1981 to 2005. We estimate both potential output and the associated output gap with quarterly data. Moreover, a model-consistent Phillips curve for an open economy is derived from simple economic relationships. Based on the estimated Phillips curve, we investigate exchange-rate pass through effects on consumer prices. We find only a weak transmission of exchange rate fluctuations into consumer prices.potential output, output gap, multivariate filter, Hirose and Kamada filter, exchange-rate pass through
Visualizing the Marrow of Science
No full textThis study proposes a new methodology that allows for
the generation of scientograms of major scientific domains,
constructed on the basis of cocitation of Institute
of Scientific Information categories, and pruned using
PathfinderNetwork, with a layout determined by algorithms
of the spring-embedder type (Kamada–Kawai),
then corroborated structurally by factor analysis. We
present the complete scientogram of the world for the
Year 2002. It integrates the natural sciences, the social
sciences, and arts and humanities. Its basic structure
and the essential relationships therein are revealed,
allowing us to simultaneously analyze the macrostructure,
microstructure, and marrow of worldwide scientific
output
Constraining FIMP from the structure formation of the Universe: analytic mapping from m(WDM)
No full textA feebly interacting massive particle (FIMP), contrasting with a weakly interacting massive particle (WIMP), is an intriguing dark matter (DM) candidate. Light (keV-scale) FIMP DM is of particular interest: its radiative decay leaves a line signal in x-ray spectra; and it is warm dark matter (WDM) and alters the galactic-scale structure formation of the Universe from that with WIMP DM. Once a possible x-ray line is reported (e.g., 3.5 keV line infers 7 keV FIMP DM), one has to check whether or not this FIMP DM is compatible with the structure formation. Here is an issue: the structure formation constraint on WDM is often reported in terms of the so-called thermal WDM mass mWDM, which cannot be directly applied to FIMP parameters. In this paper, we introduce a benchmark FIMP model that represents well a broad class of FIMP models. A big advantage of this benchmark is that we can derive the analytic formula of the non-thermal phase space distribution of FIMPs produced from freeze-in processes. By further deriving a certain "warmness" quantity, we can analytically map mWDM to FIMP parameters. Our analytic map indicates that 7 keV FIMP DM, without entropy production or a degenerate spectrum, is in tension with the latest Lyman-alpha forest data. Our analytic map will be very useful for future updates of observational constraints and reports of x-ray lines. It is also very easy to incorporate our analytic formula into a Boltzmann solver so that a linear matter power spectrum is readily accessible. Our benchmark model will facilitate FIMP searches and particle physics model-building. c. 2019 IOP Publishing Ltd and Sissa Medialab11Nsciescopu
Photoemission studies of the Na/Ge(111)-3x1 surface
No full textThe electronic structure of a Na/Ge(111)3 x 1 surface was investigated by valence-band and core-level photoemission spectroscopy with synchrotron radiation. The two-dimensional energy-band dispersion of the surface Brillouin zone along (M) over bar-<(Gamma)over bar>-(K) over bar was mapped out. The experimental surface-state dispersions show a better agreement with the theoretical results for the buckled Seiwatz model than the extended Pandey model. The surface core-level shift of the (3 x 1) surface is explained on the basis of the buckled Seiwatz model. The (3 x 1) surface reveals more covalent bonding character than other Na-adsorbed surfaces at room temperature, and its surface Fermi level is close to the valence-band maximum.Partial financial support was provided by the Centre for Molecular
Science and the Pohang Light Source. One of us (JMS) was supported by the Basic Science
Research Institute Programme, Ministry of Education, 1995, Project No BSRI-95-2433
Angle-resolved photoemission of InSb(111)-2x2
No full textThe electronic band structure of InSb(111) along the Gamma-Lambda-L[111] direction was determined using angle-resolved photoemission spectroscopy for the photon energy between 9 and 39 eV via synchrotron radiation. The bulk band dispersion is in agreement with earlier theoretical calculations. The In- (group III-) terminated InSb(111) surface shows surface Umklapp transitions and reflection of the bulk density of states. We found two nondispersive features which were not reported before. They are related to the surface state and the resonance process of the InSb(111)-2 x 2.Financial
support was partially provided by the Centre for Molecular Science and the Pohang Light
Source. One of us (J M Seo) was supported by the Basic Science Research Institute
Programme, Ministry of Education, 1994, Project No BSRI-94-2433
Trajectory Optimization Strategies for Supercavitating Underwater Vehicles
No full textSupercavitating vehicles are characterized by substantially reduced hydrodynamic drag with respect to fully wetted underwater vehicles. Drag is localized at the nose of the vehicle, where a cavitator generates a cavity that completely envelops the body. This causes the center of pressure to be always ahead of the center of mass, thus violating a fundamental principle of hydrodynamic stability. This unique loading configuration, the complex and non-linear nature of the interaction forces between vehicle and cavity, and the unsteady behavior of the cavity itself make the control and maneuvering of Supercavitating vehicles particularly challenging. This study represents an initial effort towards the evaluation of optimal trajectories for this class of underwater vehicles, which often need to operate in unsteady regimes and near the boundaries of the flight envelope. Flight trajectories and maneuvering strategies for Supercavitating vehicles are here obtained through the solution of an optimal control problem. Given a cost function and general constraints and bounds on states and controls, the solution of the optimal control problem yields the control time histories that maneuver the vehicle according to a desired strategy, together with the associated flight path. The optimal control problem is solved using the direct transcription method, which does not require the derivation of the equations of optimal control and leads to the solution of a discrete parameter optimization problem. Examples of maneuvers and resulting trajectories are given to demonstrate the effectiveness of the proposed methodology and the generality of the formulation
Surface core-level shift of InSb(111)-2x2
No full textSurface core-level photoemission of InSb(111)-2x2 was performed using a synchrotron radiation light source. There were two surface components of the In 4d core level. A higher binding component of In 4d is attributed to the surface In bonded to Sb atoms. The lower binding component with smaller intensity is due to the surface In cluster atoms. On the other hand, we were not able to observe any surface components in the Sb 4d core level. This puzzling behavior is interpreted with a different contribution of surface and bulk Madelung potential to the surface core-level shifts in relation with the atomic geometry.Financial support has been partially
provided by the Center for Molecular Science and the Pohang
Light Source. One of us ~J. M. S.! was supported by the
Basic Science Research Institute Program, Ministry of Education,
1994, Project No. BSRI-94-2433
Escalating core formation with dark matter self-heating
No full text© 2020 American Physical Society. Exothermic scatterings of dark matter (DM) produce DM particles with significant kick velocities inside DM halos. In collaboration with DM self-interaction, the excess kinetic energy of the produced DM particles is distributed to the others, which self-heats the DM particles as a whole. The DM self-heating is efficient towards the halo center, and the heat injection is used to enhance the formation of a uniform density core inside halos. The effect of DM self-heating is expected to be more significant in smaller halos for two reasons: 1) the exothermic cross section times the relative velocity, , is constant; 2) and the ratio of the injected heat to the velocity dispersion squared gets larger toward smaller-size halos. For the first time, we quantitatively investigate the core formation from DM self-heating for halos in a wide mass range (10(9)-10(15) M-circle dot) using the gravothermal fluid formalism. Notably, we demonstrate that the core formation is sharply escalating toward smaller-size halos by taking the self-heating DM (i.e., DM that semiannihilates and self-interacts) as an example. We show that the sharp escalation of the core formation may cause a tension in simultaneously explaining the observed central mass deficit of Milky Way satellites and field dwarf/low surface brightness spiral galaxies. We expect DM self-heating to be present also in other models that exhibit exothermic scatterings and self-interaction of DM, which can appreciably contribute to the core formation of DM halos11Nsciescopu
heating of strongly interacting massive particles
No full textIt was recently pointed out that semiannihilating dark matter (DM) may experience a novel temperature evolution dubbed as self-heating. Exothermic semiannihilation converts the DM mass to the kinetic energy. This yields a unique DM temperature evolution, T-chi alpha 1/a, in contrast to T-chi alpha 1/a(2) for free-streaming nonrelativistic particles. Self-heating continues as long as self-scattering sufficiently redistributes the energy of DM particles. In this paper, we study the evolution of cosmological perturbations in self-heating DM. We find that sub-GeV self-heating DM leaves a cutoff on the subgalactic scale of the matter power spectrum when the self-scattering cross section is sigma(self)/m(chi) similar to O(1) cm(2)/g. Then we present a particle physics realization of the self-heating DM scenario. The model is based on recently proposed strongly interacting massive particles with pionlike particles in a QCD-like sector. Pionlike particles semiannihilate into an axionlike particle, which is thermalized with dark radiation. The dark radiation temperature is smaller than the standard model temperature, evading the constraint from the effective number of neutrino degrees of freedom. It is easily realized when the dark sector is populated from the standard model sector through a small coupling11Nsciescopu
Virtual knots and links with unknotting index (n,m)
No full textIn [13], K. Kaur, S. Kamada et al. posed a problem of finding a virtual knot, if exists, with an unknotting index (n,m), for any pair of non-negative integers (n,m). In this paper, we address this question by providing infinite families of virtual knots with unknotting index (n,m), for a given pair of non-negative integers (n,m). Additionally, we extend our result for virtual links also
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