28,210 research outputs found
Order parameter and detection for crystallized dipolar bosons in lattices
We explore the ground-state properties of bosons with dipole-dipole
interactions in a one-dimensional optical lattice. Remarkably, a
crystallization process happens for strong dipolar interactions. Herein, we
provide a detailed characterization and a way to measure the resulting crystal
phase. Using the eigenvalues of the reduced one-body density matrix we define
an order parameter that yields a phase diagram in agreement with an analysis of
the density and two-body density. We demonstrate that the phase diagram can be
detected experimentally using the variance of single-shot measurements.Comment: 6 pages, 3 figures. Supplementary Information included. Software
available at http://ultracold.org
Low-lying dipole strengths for probable -wave one-neutron halos in the medium mass region
The one-neutron halos lying in the island of inversion around has
provided the podium, to study the variation of total low-lying dipole strength
with the neutron separation energy. We study three probable p-wave one-neutron
halo candidates 31Ne and 34Na and 37Mg lying in the island of inversion. A
simple analytic model has been used for the calculation of the total low-lying
dipole strength for the medium mass p-wave one-neutron halos. A correction
factor to this analytical model has been estimated with a realistic Woods-Saxon
potential. A comparison of these analytic calculations has been made with the
those performed by a finite-range distorted-wave Born approximation theory of
the Coulomb dissociation. We also make an estimate of the one-neutron
separation energies of 31Ne, 34Na and 37Mg.Comment: 7 pages latex, 4 figures, to appear in EPJ
Constraining Compact Object Formation with 2M0521
We show that the recently discovered binary 2M05215658+4359220 (2M0521),
comprised of a giant star (GS) orbiting a suspected black hole (BH) in a ~80
day orbit, may be instrumental in shedding light on uncertain BH-formation
physics and can be a test case for studying wind accretion models. Using binary
population synthesis with a realistic prescription for the star formation
history and metallicity evolution of the Milky Way, we analyze the evolution of
binaries containing compact objects (COs) in orbit around GSs with properties
similar to 2M0521. We find ~100-1000 CO-GS binaries in the Milky Way observable
by Gaia, and 0-12 BH-GS and 0-1 neutron star-GS binaries in the Milky Way with
properties similar to 2M0521. We find that all CO-GSs with Porb<5 yr, including
2M0521, go through a common envelope (CE) and hence form a class of higher mass
analogs to white dwarf post-CE binaries. We further show how the component
masses of 2M0521-like binaries depend strongly on the supernova-engine model we
adopt. Thus, an improved measurement of the orbit of 2M0521, imminent with
Gaia's third data release, will strongly constrain its component masses and as
a result inform supernova-engine models widely used in binary population
synthesis studies. These results have widespread implications for the origins
and properties of CO binaries, especially those detectable by LIGO and LISA.
Finally, we show that the reported X-ray non-detection of 2M0521 is a challenge
for wind accretion theory, making 2M0521-like CO-GS binaries a prime target for
further study with accretion models.Comment: 7 pages, 5 figures, Accepted for Publication in ApJ
Tied Versus Untied Foreign Aid: Consequences for a Growing Economy
This paper contrasts the effects of tied and untied foreign aid programs on the welfare and macroeconomic performance of a small open economy. We show that the acceptance of tied aid inevitably obligates the recipient economy to undertake certain internal structural adjustments, and the flexibility it possesses to undertake these adjustments eventually determines the effectiveness of the aid program. The economic consequences of tied and untied aid programs, their relative merits from a welfare standpoint, and the transitional dynamics depend crucially upon several characteristics of the recipient economy that summarize this flexibility. These include: (i) the costs of installing public capital relative to private capital (intertemporal adjustment costs), (ii) the substitutability between factors of production (intratemporal adjustment costs), (iii) the flexibility of labor supply (work effort), (iv) the recipient's degree of access to the world financial markets (capital market imperfections), and (v) the recipient's opportunities for co-financing infrastructure projects by domestic resourcesForeign aid, International transfers, Economic growth, Public investment
Application of edge-based finite elements and vector ABCs in 3D scattering
A finite element absorbing boundary condition (FE-ABC) solution of the scattering by arbitrary 3-D structures is considered. The computational domain is discretized using edge-based tetrahedral elements. In contrast to the node-based elements, edge elements can treat geometries with sharp edges, are divergence-less, and easily satisfy the field continuity condition across dielectric interfaces. They do, however, lead to a higher unknown count but this is balanced by the greater sparsity of the resulting finite element matrix. Thus, the computation time required to solve such a system iteratively with a given degree of accuracy is less than the traditional node-based approach. The purpose is to examine the derivation and performance of the ABC's when applied to 2-D and 3-D problems and to discuss the specifics of our FE-ABC implementation
Non-Zero Sum Games for Reactive Synthesis
In this invited contribution, we summarize new solution concepts useful for
the synthesis of reactive systems that we have introduced in several recent
publications. These solution concepts are developed in the context of non-zero
sum games played on graphs. They are part of the contributions obtained in the
inVEST project funded by the European Research Council.Comment: LATA'16 invited pape
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