5,428 research outputs found
Photon-assisted Landau-Zener transition: Role of coherent superposition states
We investigate a Landau-Zener (LZ) transition process modeled by a quantum
two-level system (TLS) coupled to a photon mode when the bias energy is varied
linearly in time. The initial state of the photon field is assumed to be a
superposition of coherent states, leading to a more intricate LZ transition.
Applying the rotating-wave approximation (RWA), analytical results are obtained
revealing the enhancement of the LZ probability by increasing the average
photon number. We also consider the creation of entanglement and the change of
photon statistics during the LZ process. Without the RWA, we find some
qualitative differences of the LZ dynamics from the RWA results, e.g., the
average photon number no longer monotonically enhances the LZ probability. The
ramifications and implications of these results are explored.Comment: 9 pages, 7 figure
Declension Narratives, Literary Representations of Mental Disability, and New England Identity Construction: A Disabilities Studies Analysis of Northern New England Texts
This thesis employs the framework of Disabilities Theory, particularly the Social-Constructivist Model, to examine the literary figure of mental disability as a robust and reflexive trope in the construction of New England\u27s regional identity at the turn of the twentieth century through the late-twentieth century
Relativistic nucleon optical potentials with isospin dependence in Dirac Brueckner Hartree-Fock approach
The relativistic optical model potential (OMP) for nucleon-nucleus scattering
is investigated in the framework of Dirac-Brueckner-Hartree-Fock (DBHF)
approach using the Bonn-B One-Boson- Exchange potential for the bare
nucleon-nucleon interaction. Both real and imaginary parts of isospin-dependent
nucleon self-energies in nuclear medium are derived from the DBHF approach
based on the projection techniques within the subtracted T -matrix
representation. The Dirac potentials as well as the corresponding Schrodinger
equivalent potentials are evaluated. An improved local density approximation is
employed in this analysis, where a range parameter is included to account for a
finite-range correction of the nucleon-nucleon interaction. As an example the
total cross sections, differential elastic scattering cross sections, analyzing
powers for n, p + 27Al at incident energy 100 keV < E < 250 MeV are calculated.
The results derived from this microscopic approach of the OMP are compared to
the experimental data, as well as the results obtained with a phenomenological
OMP. A good agreement between the theoretical results and the measurements can
be achieved for all incident energies using a constant value for the range
parameter.Comment: 10 pages, 16 figure
Effects of diagonal disorder on Charge Density Wave and Superconductivity in local pair systems
We analyse the influence of diagonal disorder (random site energy) on Charge
Density Wave (CDW) and Superconductivity (SS) in local pair systems which are
described by the model of hard core charged bosons on a lattice. This problem
was previously studied within the mean field approximation for the case of half
filled band (n = 1). Here we extend that investigation to the case of arbitrary
particle concentration (0 < n < 2) and examine the phase diagrams of the model
and the behaviour of superfluid density as a function of n and the increasing
disorder. Depending on the strength of random on-site energies, the intersite
density-density repulsion and the concentration the model can exhibit several
various phases, including homogeneous phases: CDW, SS and Bose-glass (NO) as
well as the phase separated states: CDW-SS, CDW-NO and particle droplets. The
obtained results for SS phase are in qualitative agreement with the available
Monte Carlo calculations for two dimensional lattice. Also, in a definite range
of parameters the system exhibits the phenomena which we call a disorder
induced superconductivity and a disorder induced charge ordering.Comment: 21 pages, 8 figure
A Collaborative Professional Development Approach to Improving Student Outcomes
The purpose of this article is to analyze the strategy used to develop a collaborative professional development process that focused on the implementation of the common core state standards. In addition, the author will report findings, and discuss the effectiveness of the initiative for postsecondary faculty. Faculty can verify that not every student comes to a two or four year college program prepared to succeed in credit bearing coursework. To facilitate improvement of student success, states across the country collaborated with teachers, researchers and leading experts to design and develop the common core state standards. The standards were developed to ensure that all students, regardless of where they live, are well prepared with the skills and knowledge essential to collaborate and compete with their peers (Common Core State Standards Initiative, 2012). Kentucky was the first state to adopt the Common Core Standards, and beginning in 2010 a large scale effort was developed to provide faculty with information about how implementation of the standards could affect postsecondary education. To address the need for information about the Common Core Standards, representatives from Kentucky institutes of higher education (IHE) collaborated in the development and delivery of information about the Common Core Standards
Self-Similar Dynamical Relaxation of Dark Matter Halos in an Expanding Universe
We investigate the structure of cold dark matter halos using advanced models
of spherical collapse and accretion in an expanding Universe. These base on
solving time-dependent equations for the moments of the phase-space
distribution function in the fluid approximation; our approach includes
non-radial random motions, and most importantly, an advanced treatment of both
dynamical relaxation effects that takes place in the infalling matter:
phase-mixing associated to shell crossing, and collective collisions related to
physical clumpiness. We find self-similar solutions for the
spherically-averaged profiles of mass density rho(r), pseudo phase-space
density Q(r) and anisotropy parameter beta(r). These profiles agree with the
outcomes of state-of-the-art N-body simulations in the radial range currently
probed by the latter; at smaller radii, we provide specific predictions. In the
perspective provided by our self-similar solutions we link the halo structure
to its two-stage growth history, and propose the following picture. During the
early fast collapse of the inner region dominated by a few merging clumps,
efficient dynamical relaxation plays a key role in producing a closely
universal mass density and pseudo phase-space density profiles; in particular,
these are found to depend only weakly on the detailed shape of the initial
perturbation and the related collapse times. The subsequent inside-out growth
of the outer regions feeds on the slow accretion of many small clumps and
diffuse matter; thus the outskirts are only mildly affected by dynamical
relaxation but are more sensitive to asymmetries and cosmological variance.Comment: 31 pages, 16 figures. Typos corrected. Accepted by Ap
Scheme for generating entangled states of two field modes in a cavity
This paper considers a two-level atom interacting with two cavity modes with
equal frequencies. Applying a unitary transformation, the system reduces to the
analytically solvable Jaynes-Cummings model. For some particular field states,
coherent and squeezed states, the transformation between the two bare basis's,
related by the unitary transformation, becomes particularly simple. It is shown
how to generate, the highly non-classical, entangled coherent states of the two
modes, both in the zero and large detuning cases. An advantage with the zero
detuning case is that the preparation is deterministic and no atomic
measurement is needed. For the large detuning situation a measurement is
required, leaving the field in either of two orthogonal entangled coherent
states.Comment: Accepted in J. Mod. Opt.; 12 pages; Replaced with revised version.
Extended discussion of experimental realizations, earlier studies in the
field and on the frequency dependence in the adiabatic eliminatio
Use of domesticated pigs by Mesolithic hunter-gatherers in northwestern Europe
Acknowledgements We thank the Archaeological State Museum Schleswig-Holstein, the Archaeological State Offices of Brandenburg, Lower Saxony and Saxony and the following individuals who provided sample material: Betty Arndt, Jo¨rg Ewersen, Frederick Feulner, Susanne Hanik, Ru¨diger Krause, Jochen Reinhard, Uwe Reuter, Karl-Heinz Ro¨hrig, Maguerita Scha¨fer, Jo¨rg Schibler, Reinhold Schoon, Regina Smolnik, Thomas Terberger and Ingrid Ulbricht. We are grateful to Ulrich Schmo¨lcke, Michael Forster, Peter Forster and Aikaterini Glykou for their support and comments on the manuscript. We also thank many institutions and individuals that provided sample material and access to collections, especially the curators of the Museum fu¨r Naturkunde, Berlin; Muse´um National d0 Histoire Naturelle, Paris; Smithsonian Institution, National Museum of Natural History, Washington D.C.; Zoologische Staatssammlung, Mu¨nchen; Museum fu¨r Haustierkunde, Halle; the American Museum of Natural History, New-York. This work was funded by the Graduate School âHuman Development in Landscapesâ at Kiel University (CAU) and supported by NERC project Grant NE/F003382/1. Radiocarbon dating was carried out at the Leibniz Laboratory, CAU. This work is licensed under a Creative Commons AttributionNonCommercial-NoDerivs 3.0 Unported License.Peer reviewedPublisher PD
The dark flow induced small scale kinetic Sunyaev Zel'dovich effect
Recently Kashlinsky et al. 2008, 2010 reported a discovery of a
km/ bulk flow of the universe out to , through the dark flow
induced CMB dipole in directions of clusters. We point out that, if this dark
flow exists, it will also induce observable CMB temperature fluctuations at
multipole , through modulation of the inhomogeneous electron
distribution on the uniform dark flow. The induced small scale kinetic Sunyaev
Zel'dovich (SZ) effect will reach \sim 1\muk^2 at multipole 10^3\la \ell\la
10^4, only a factor of smaller than the conventional kinetic SZ
effect. Furthermore, it will be correlated with the large scale structure (LSS)
and its correlation with 2MASS galaxy distribution reaches K at
, under a directional dependent optimal weighting scheme. We
estimate that, WMAP plus 2MASS should already be able to detect this dark flow
induced small scale kinetic SZ effect with confidence. Deeper
galaxy surveys such as SDSS can further improve the measurement. Planck plus
existing galaxy surveys can reach \ga 14\sigma detection. Existing CMB-LSS
cross correlation measurements shall be reanalyzed to test the existence of the
dark flow and, if it exists, shall be used to eliminate possible bias on the
integrated Sachs-Wolfe effect measurement through the CMB-LSS cross
correlation.Comment: Minor revisions. 5 pages, 3 figures. MNRAS letters in pres
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