A Sunyaev-Zel'Dovich-Selected Sample of the Most Massive Galaxy Clusters in the 2500 deg^2 South Pole Telescope Survey

The South Pole Telescope (SPT) is currently surveying 2500 deg^2 of the southern sky to detect massive galaxy clusters out to the epoch of their formation using the Sunyaev-Zel'dovich (SZ) effect. This paper presents a catalog of the 26 most significant SZ cluster detections in the full survey region. The catalog includes 14 clusters which have been previously identified and 12 that are new discoveries. These clusters were identified in fields observed to two differing noise depths: 1500 deg^2 at the final SPT survey depth of 18 μK arcmin at 150 GHz and 1000 deg^2 at a depth of 54 μK arcmin. Clusters were selected on the basis of their SZ signal-to-noise ratio (S/N) in SPT maps, a quantity which has been demonstrated to correlate tightly with cluster mass. The S/N thresholds were chosen to achieve a comparable mass selection across survey fields of both depths. Cluster redshifts were obtained with optical and infrared imaging and spectroscopy from a variety of ground- and space-based facilities. The redshifts range from 0.098 ≤ z ≤ 1.132 with a median of z_(med) = 0.40. The measured SZ S/N and redshifts lead to unbiased mass estimates ranging from 9.8 × 10^(14) M_☉ h^(–1)_(70) ≤ M _(200(ρmean)) ≤ 3.1 × 10^(15) M_☉ h^(–1)_(70). Based on the SZ mass estimates, we find that none of the clusters are individually in significant tension with the ΛCDM cosmological model. We also test for evidence of non-Gaussianity based on the cluster sample and find the data show no preference for non-Gaussian perturbations

It’s a long way to Monte-Carlo: probabilistic display in GPS navigation

We present a mobile, GPS-based multimodal navigation system, equipped with inertial control that allows users to explore and navigate through an augmented physical space, incorporating and displaying the uncertainty resulting from inaccurate sensing and unknown user intentions. The system propagates uncertainty appropriately via Monte Carlo sampling and predicts at a user-controllable time horizon. Control of the Monte Carlo exploration is entirely tilt-based. The system output is displayed both visually and in audio. Audio is rendered via granular synthesis to accurately display the probability of the user reaching targets in the space. We also demonstrate the use of uncertain prediction in a trajectory following task, where a section of music is modulated according to the changing predictions of user position with respect to the target trajectory. We show that appropriate display of the full distribution of potential future users positions with respect to sites-of-interest can improve the quality of interaction over a simplistic interpretation of the sensed data

Show me the way to Monte Carlo: density-based trajectory navigation

We demonstrate the use of uncertain prediction in a system for pedestrian navigation via audio with a combination of Global Positioning System data, a music player, inertial sensing, magnetic bearing data and Monte Carlo sampling for a density following task, where a listener’s music is modulated according to the changing predictions of user position with respect to a target density, in this case a trajectory or path. We show that this system enables eyes-free navigation around set trajectories or paths unfamiliar to the user and demonstrate that the system may be used effectively for varying trajectory width and context

Kapton charging characteristics: Effects of material thickness and electron-energy distribution

Charging characteristics of polyimide (Kapton) of varying thicknesses under irradiation by a very-low-curent-density electron beam, with the back surface of the sample grounded are reported. These charging characteristics are in good agreement with a simple analytical model which predicts that in thin samples at low current density, sample surface potential is limited by conduction leakage through the bulk material. The charging of Kapton in a low-current-density electron beam in which the beam energy was modulated to simulate Maxwellian and biMaxwellian distribution functions is measured

Radio-wave propagation in the non-Gaussian interstellar medium

Radio waves propagating from distant pulsars in the interstellar medium (ISM), are refracted by electron density inhomogeneities, so that the intensity of observed pulses fluctuates with time. The theory relating the observed pulse time-shapes to the electron-density correlation function has developed for 30 years, however, two puzzles have remained. First, observational scaling of pulse broadening with the pulsar distance is anomalously strong; it is consistent with the standard model only when non-uniform statistics of electron fluctuations along the line of sight are assumed. Second, the observed pulse shapes are consistent with the standard model only when the scattering material is concentrated in a narrow slab between the pulsar and the Earth. We propose that both paradoxes are resolved at once if one assumes stationary and uniform, but non-Gaussian statistics of the electron-density distribution. Such statistics must be of Levy type, and the propagating ray should exhibit a Levy flight. We propose that a natural realization of such statistics may be provided by the interstellar medium with random electron-density discontinuities. We develop a theory of wave propagation in such a non-Gaussian random medium, and demonstrate its good agreement with observations. The qualitative introduction of the approach and the resolution of the anomalous-scaling paradox was presented earlier in [PRL 91, 131101 (2003); ApJ 584, 791 (2003)].Comment: 27 pages, changes to match published versio

Spinodal fractionation in a polydisperse square well fluid

Using Kinetic Monte Carlo simulation, we model gas-liquid spinodal decomposition in a size-polydisperse square well fluid, representing a 'near-monodisperse' colloidal dispersion. We find that fractionation (demixing) of particle sizes between the phases begins asserting itself shortly after the onset of phase ordering. Strikingly, the direction of size fractionation can be reversed by a seemingly trivial choice between two inter-particle potentials which, in the monodisperse case, are identical -- we rationalise this in terms of a perturbative, equilibrium theory of polydispersity. Furthermore, our quantitative results show that Kinetic Monte Carlo simulation can provide detailed insight into the role of fractionation in real colloidal systems.Comment: 7 pages, 7 figures, to be published in Phys. Rev.

Population Aging, Elderly Migration and Education Spending: Intergenerational Conflict Revisited

Elderly have been increasingly targeted as a group to enhance economic development and the tax base in communities. While recent literature on elderly migration tends to focus on how elderly migration patterns are influenced by state fiscal variables, the reverse effect from elderly population on fiscal variables is very plausible. This paper reexamines the intergenerational conflict in education financing using U.S. state and county level data. We analyze how preferences for education spending might vary across different elderly age groups, an analysis that has not been explored before. We estimate the impact of elderly population and elderly migration rates on education spending using panel data and spatial econometric techniques. Our results broadly support the presence of intergenerational conflict and age heterogeneity in preferences for education spending among elderly migrants.population aging, elderly migration, education spending, intergenerational conflict

Correlation induced non-Abelian quantum holonomies

In the context of two-particle interferometry, we construct a parallel transport condition that is based on the maximization of coincidence intensity with respect to local unitary operations on one of the subsystems. The dependence on correlation is investigated and it is found that the holonomy group is generally non-Abelian, but Abelian for uncorrelated systems. It is found that our framework contains the L\'{e}vay geometric phase [2004 {\it J. Phys. A: Math. Gen.} {\bf 37} 1821] in the case of two-qubit systems undergoing local SU(2) evolutions.Comment: Minor corrections; journal reference adde

What can GLAST say about the origin of cosmic rays in other galaxies ?

Gamma rays in the band from 20 MeV to 300 GeV, used in combination with data from radio and X-ray bands, provide a powerful tool for studying the origin of cosmic rays in our sister galaxies Andromeda and the Magellanic Clouds. Gamma-ray Large Area Space Telescope (GLAST) will spatially resolve these galaxies and measure the spectrum and intensity of diffuse gamma radiation from the collisions of cosmic rays with gas and dust in them. Observations of Andromeda will give an external perspective on a spiral galaxy like the Milky Way. Observations of the Magellanic Clouds will permit a study of cosmic rays in dwarf irregular galaxies, where the confinement is certainly different and the massive star formation rate is much greater.Comment: 4 pages including 6 figures; to appear in Proc. ACE-2000 Symp. "The Acceleration and Transport of Energetic Particles Observed in the Heliosphere" (Jan. 5-8, 2000, Indian Wells, CA), AIP Conf. Proc. More details can be found at the LHEA GLAST page at http://lhea-glast.gsfc.nasa.gov/pub/science/index.htm

An 8-cm ion thruster characterization

The performance of the Ion Auxiliary Propulsion System (IAPS) thruster was increased to thrust T = 32 mN, specific impulse I sub sp = 4062 s, and thrust-to-power ratio T/P = 33 mN/kW. This performance was obtained by increasing the discharge power, accelerating voltage, propellant flow rate, and chamber magnetic field. Adding a plenum and main vaporizer for propellant distribution was the only major change required in the thruster. The modified thruster characterization is presented. A cathode magnet assembly did not improve performance. A simplified power processing unit was designed and evaluated. This unit decreased the parts count of the IAPS power processing unit by a factor of ten