Quadrature noise in light propagating through a cold 87Rb atomic gas

We report on the study of the noise properties of laser light propagating through a cold 87Rb atomic sample held in a magneto-optical trap. The laser is tuned around the Fg = 2 \rightarrow Fe = 1, 2 D1 transitions of 87Rb. We observe quadrature-dependent noise in the light signal, an indication that it may be possible to produce squeezed states of light. We measure the minimum and maximum phase-dependent noise as a function of detuning and compare these results to theoretical predictions to explore the best conditions for light squeezing using cold atomic Rb

Challenges to optimal medicines use in people living with dementia and their caregivers: A literature review

Dementia is fast becoming a global concern due to a demographic shift towards an older population. Many studies have shown that caring for a family member or friend has a profound and negative impact on the physical, emotional and psychosocial aspects of the caregivers’ life. One significant activity that a family caregiver undertakes is assistance with the management of medicines. This review was undertaken to ascertain what the issues are that affect optimal medicines use from the perspectives of people living with dementia and their caregivers, both in the community and care home settings. A literature search was conducted using electronic databases, employing a combination of search terms. A total of 16 studies met the inclusion criteria. Six broad themes were identified, together with some recommendations to improve medicines use in people with dementia. Challenges to medicines use centred on medicines management and administration, the impact on the caregiver and care recipient, their partnership and interface with formal care. Future research should focus on developing targeted interventions that can overcome these challenges to achieve optimal medicines use

Network Creation Games: Think Global - Act Local

We investigate a non-cooperative game-theoretic model for the formation of communication networks by selfish agents. Each agent aims for a central position at minimum cost for creating edges. In particular, the general model (Fabrikant et al., PODC'03) became popular for studying the structure of the Internet or social networks. Despite its significance, locality in this game was first studied only recently (Bil\`o et al., SPAA'14), where a worst case locality model was presented, which came with a high efficiency loss in terms of quality of equilibria. Our main contribution is a new and more optimistic view on locality: agents are limited in their knowledge and actions to their local view ranges, but can probe different strategies and finally choose the best. We study the influence of our locality notion on the hardness of computing best responses, convergence to equilibria, and quality of equilibria. Moreover, we compare the strength of local versus non-local strategy-changes. Our results address the gap between the original model and the worst case locality variant. On the bright side, our efficiency results are in line with observations from the original model, yet we have a non-constant lower bound on the price of anarchy.Comment: An extended abstract of this paper has been accepted for publication in the proceedings of the 40th International Conference on Mathematical Foundations on Computer Scienc

MCG+00-32-16: An Irregular Galaxy Close to the Lowest Redshift Absorber on the 3C 273 Line of Sight

MCG+00-32-16 is the galaxy closest in position-velocity space to the lowest redshift Ly$\alpha$ absorber along the line-of-sight to the quasar 3C 273. Its projected separation is 204 (d/19 Mpc) kpc, where d is the distance from the Milky Way to the galaxy, and the redshift difference is only 94 km/s; HI 1225+01 is slightly closer in projected separation to the absorber, but has a greater redshift difference. We present HI synthesis array mapping and CCD photometry in B and R for MCG+00-32-16. The HI disk is rotating in such a way that the side of the galaxy closer to the sight-line to the quasar has the larger velocity difference from the absorber. The absorber may be a ``failed dwarf'' member of a poor galaxy group of which MCG+00-32-16 and HI 1225+01 are the only members to have formed stars.Comment: 14 pages, 9 figures, accepted by Astrophysical Journa

Exact Solution of a Yang-Baxter Spin-1/2 Chain Model and Quantum Entanglement

Entanglement is believed to be crucial in macroscopic physical systems for understanding the collective quantum phenomena such as quantum phase transitions. We start from and solve exactly a novel Yang-Baxter spin-1/2 chain model with inhomogeneous and anisotropic short-range interactions. For the ground state, we show the behavior of neighboring entanglement in the parameter space and find that the inhomogeneous coupling strengths affect entanglement in a distinctive way from the homogeneous case, but this would not affect the coincidence between entanglement and quantum criticality.Comment: 7 pages, 3 figure

Quantum Phase Transition of Spin-2 Cold Bosons in an Optical Lattice

The Bose-Hubbard Hamiltonian of spin-2 cold bosons with repulsive interaction in an optical lattice is proposed. After neglecting the hopping term, the site-independent Hamiltonian and its energy eigenvalues and eigenstates are obtained. We consider the hopping term as a perturbation to do the calculations in second order and draw the phase diagrams for different cases. The phase diagrams show that there is a phase transition from Mott insulator with integer number bosons to superfluid when the ratio $c_0/t$ ($c_0$ is the spin-independent on-site interaction and $t$ the hopping matrix element between adjacent lattice sites) is decreased to a critical value and that there is different phase boundary between superfluid and Mott insulator phase for different Zeeman level component in some ground states. We find that the position of phase boundary for different Zeeman level component is related to its average population in the Mott ground state.Comment: 16 pages, 6 figure

Public goods and decay in networks

We propose a simple behavioral model to analyze situations where (1) a group of agents repeatedly plays a public goods game within a network structure and (2) each agent only observes the past behavior of her neighbors, but is affected by the decisions of the whole group. The model assumes that agents are imperfect conditional cooperators, that they infer unobserved contributions assuming imperfect conditional cooperation by others, and that they have some degree of bounded rationality. We show that our model approximates quite accurately regularities derived from public goods game experiments

A Study of Lyman-Alpha Quasar Absorbers in the Nearby Universe

Spectroscopy of ten quasars obtained with the Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) is presented. A clustering analysis reveals an excess of nearest neighbor line pairs on velocity scales of 250-750 km/s at a 95-98% confidence level. The hypothesis that the absorbers are randomly distributed in velocity space can be ruled out at the 99.8% confidence level. No two-point correlation power is detected (xi < 1 with 95% confidence). Lyman-alpha absorbers have correlation amplitudes on scales of 250-500 km/s at least 4-5 times smaller than the correlation amplitude of bright galaxies. A detailed comparison between absorbers in nearby galaxies is carried out on a limited subset of 11 Lyman- alpha absorbers where the galaxy sample in a large contiguous volume is complete to M_B = -16. Absorbers lie preferentially in regions of intermediate galaxy density but it is often not possible to uniquely assign a galaxy counterpart to an absorber. This sample provides no explicit support for the hypothesis that absorbers are preferentially associated with the halos of luminous galaxies. We have made a preliminary comparison of the absorption line properties and environments with the results of hydrodynamic simulations. The results suggest that the Lyman-alpha absorbers represent diffuse or shocked gas in the IGM that traces the cosmic web of large scale structure. (abridged)Comment: 36 pages of text, 15 figures, 4 tables, 36 file

Full orbital calculation scheme for materials with strongly correlated electrons

We propose a computational scheme for the ab initio calculation of Wannier functions (WFs) for correlated electronic materials. The full-orbital Hamiltonian H is projected into the WF subspace defined by the physically most relevant partially filled bands. The Hamiltonian H^{WF} obtained in this way, with interaction parameters calculated by constrained LDA for the Wannier orbitals, is used as an ab initio setup of the correlation problem, which can then be solved by many-body techniques, e.g., dynamical mean-field theory (DMFT). In such calculations the self-energy operator \Sigma(e) is defined in WF basis which then can be converted back into the full-orbital Hilbert space to compute the full-orbital interacting Green function G(r,r',e). Using G(r,r',e) one can evaluate the charge density, modified by correlations, together with a new set of WFs, thus defining a fully self-consistent scheme. The Green function can also be used for the calculation of spectral, magnetic and electronic properties of the system. Here we report the results obtained with this method for SrVO3 and V2O3. Comparisons are made with previous results obtained by the LDA+DMFT approach where the LDA DOS was used as input, and with new bulk-sensitive experimental spectra.Comment: 36 pages, 14 figure

Spectroscopic Identification of a Proto-Cluster at z=2.300: Environmental Dependence of Galaxy Properties at High Redshift

We have discovered a highly significant over-density of galaxies at z=2.300+/-0.015 in the course of a redshift survey designed to select star-forming galaxies in the redshift range z=2.3+/-0.4 in the field of the bright z=2.72 QSO HS1700+643. The structure has a redshift-space galaxy over-density of delta_g,z ~= 7 and an estimated matter over-density in real space of delta_m ~= 1.8, indicating that it will virialize by z~0 with a mass scale of ~= 1.4x10^15 M_sun, that of a rich galaxy cluster. Detailed modeling of the spectral energy distribution -- from the rest-far-UV to the rest-near-IR -- of the 72 spectroscopically confirmed galaxies in this field for which we have obtained K_s and Spitzer/IRAC photometry, allows for a first direct comparison of galaxy properties as a function of large-scale environment at high redshift. We find that galaxies in the proto-cluster environment have mean stellar masses and inferred ages that are ~2 times larger (at z=2.30) than identically UV-selected galaxies outside of the structure, and show that this is consistent with simple theoretical expectations for the acceleration of structure formation in a region that is over-dense on large scales by the observed amount. The proto-cluster environment contains a significant number of galaxies that already appear old, with large stellar masses (>10^11 M_sun), by z=2.3.Comment: 7 pages including 3 figures. Accepted for publication in ApJ. Typo correcte