Investigations on T violation and CPT symmetry in the neutral kaon system -- a pedagogical approach --

During the recent years experiments with neutral kaons have yielded remarkably sensitive results which are pertinent to such fundamental phenomena as CPT invariance (protecting causality), time-reversal invariance violation, coherence of wave functions, and entanglement of kaons in pair states. We describe the phenomenological developments and the theoretical conclusions drawn from the experimental material. An outlook to future experimentation is indicated.Comment: 41 pages, 9 figures. See arXiv:hep-ph/0603075 for an enlarged versio

Development of a key performance indicator system to benchmark relative paratransit performance

The Americans with Disabilities Act of 1990 prohibits discrimination against people with disabilities. US transit agencies are therefore required to offer services to eligible customers that complement the mobility opportunities provided to the general public on fixed-route public transit. While these paratransit services are necessary and just, they represent a proportionally large cost to agencies: approximately eight times the cost per boarding compared to fixed-route bus service. To be able to identify opportunities for (cost) efficiencies, and to further improve the quality of paratransit services offered, the twenty agencies of the American Bus Benchmarking Group (ABBG) decided to benchmark their relative performance in paratransit management and operations. To ensure comparability of agencies’ performance and hence ensure the usefulness of the benchmarking program, a key performance indicator system was developed and associated data items were defined in detail. The scope of this system went beyond the data already provided to the National Transit Database, both in amount and granularity of data collected, as well as the detail of definitions. This paper describes the challenges, respective solutions, and other lessons identified during four years of paratransit benchmarking development led by Imperial College London, the ABBG facilitators. The paper provides transit agencies and authorities as well as benchmarking practitioners and academics an opportunity to apply these lessons for the further benefit of paratransit services and their customers around the U.S

Casimir Force at a Knife's Edge

The Casimir force has been computed exactly for only a few simple geometries, such as infinite plates, cylinders, and spheres. We show that a parabolic cylinder, for which analytic solutions to the Helmholtz equation are available, is another case where such a calculation is possible. We compute the interaction energy of a parabolic cylinder and an infinite plate (both perfect mirrors), as a function of their separation and inclination, $H$ and $\theta$, and the cylinder's parabolic radius $R$. As $H/R\to 0$, the proximity force approximation becomes exact. The opposite limit of $R/H\to 0$ corresponds to a semi-infinite plate, where the effects of edge and inclination can be probed.Comment: 5 pages, 3 figures, uses RevTeX; v2: expanded conclusions; v3: fixed missing factor in Eq. (3) and incorrect diagram label (no changes to results); v4: fix similar factor in Eq. (16) (again no changes to results

(Dodecafluorosubphthalocyaninato)(4-methylphenolato)boron(III)

In the title compound, C31H7BF12N6O, mol­ecules are arranged into one-dimensional columns with an inter­molecular B⋯B distance of 5.3176 (8) Å. Bowl-shaped mol­ecules are arranged within the columns in a concave bowl-to-ligand arrangement separated by a ring centroid distance of 3.532 (2) Å between the benzene ring of the 4-methyl­phen­oxy ligand and one of the three five-membered rings of a symmetry-related mol­ecule

Energy, Central Charge, and the BPS Bound for 1+1 Dimensional Supersymmetric Solitons

We consider one-loop quantum corrections to soliton energies and central charges in the supersymmetric $\phi^4$ and sine-Gordon models in 1+1 dimensions. In both models, we unambiguously calculate the correction to the energy in a simple renormalization scheme and obtain $\Delta H = - m/(2\pi)$, in agreement with previous results. Furthermore, we show that there is an identical correction to the central charge, so that the BPS bound remains saturated in the one-loop approximation. We extend these results to arbitrary 1+1 dimensional supersymmetric theories.Comment: 15 pages, RevTeX; v2: generalized energy result, added minor clarifications, and fixed typos; v3: more minor clarifications and corrections; v4: fixed factor of 2 in eq. (25); v5: fixed minor error in eq. (55

Integral Field Spectroscopy of HH 262: The Spectral Atlas

HH 262 is a group of emitting knots displaying an "hour-glass" morphology in the Halpha and [SII] lines, located 3.5' to the northeast of the young stellar object L1551-IRS5, in Taurus. We present new results of the kinematics and physical conditions of HH 262 based on Integral Field Spectroscopy covering a field of 1.5'x3', which includes all the bright knots in HH 262. These data show complex kinematics and significant variations in physical conditions over the mapped region of HH 262 on a spatial scale of <3". A new result derived from the IFS data is the weakness of the [NII] emission (below detection limit in most of the mapped region of HH 262), including the brightest central knots. Our data reinforce the association of HH 262 with the redshifted lobe of the evolved molecular outflow L1551-IRS5. The interaction of this outflow with a younger one, powered by L1551 NE, around the position of HH 262 could give rise to the complex morphology and kinematics of HH 262.Comment: Accepted for publication in MNRA

State-dependent diffusion: thermodynamic consistency and its path integral formulation

The friction coefficient of a particle can depend on its position as it does when the particle is near a wall. We formulate the dynamics of particles with such state-dependent friction coefficients in terms of a general Langevin equation with multiplicative noise, whose evaluation requires the introduction of specific rules. Two common conventions, the Ito and the Stratonovich, provide alternative rules for evaluation of the noise, but other conventions are possible. We show the requirement that a particle's distribution function approach the Boltzmann distribution at long times dictates that a drift term must be added to the Langevin equation. This drift term is proportional to the derivative of the diffusion coefficient times a factor that depends on the convention used to define the multiplicative noise. We explore the consequences of this result in a number examples with spatially varying diffusion coefficients. We also derive path integral representations for arbitrary interpretation of the noise, and use it in a perturbative study of correlations in a simple system.Comment: 18 pages, 8 figures, Accepted to PR

Evaporation and condensation of spherical interstellar clouds. Self-consistent models with saturated heat conduction and cooling

Shortened version: The fate of IS clouds embedded in a hot tenuous medium depends on whether the clouds suffer from evaporation or whether material condensates onto them. Analytical solutions for the rate of evaporative mass loss from an isolated spherical cloud embedded in a hot tenuous gas are deduced by Cowie & McKee (1977). In order to test the validity of the analytical results for more realistic IS conditions the full hydrodynamical equations must be treated. Therefore, 2D numerical simulations of the evolution of IS clouds %are performed with different internal density structures and surrounded by a hot plasma reservoir. Self-gravity, interstellar heating and cooling effects and heat conduction by electrons are added. Classical thermal conductivity of a fully ionized hydrogen plasma and saturated heat flux are considered. Using pure hydrodynamics and classical heat flux we can reproduce the analytical results. Heat flux saturation reduces the evaporation rate by one order of magnitude below the analytical value. The evolution changes totally for more realistic conditions when interstellar heating and cooling effects stabilize the self-gravity. Evaporation then turns into condensation, because the additional energy by heat conduction can be transported away from the interface and radiated off efficiently from the cloud's inner parts. I.e. that the saturated heat flux consideration is inevitable for IS clouds embedded in hot tenuous gas. Various consequences are discussed in the paper.Comment: 16 pages, 24 figures, accepted in Astronomy and Astrophysic

On the Correlations between Galaxy Properties and Supermassive Black Hole Mass

We use a large sample of upper limits and accurate estimates of supermassive black holes masses coupled with libraries of host galaxy velocity dispersions, rotational velocities and photometric parameters extracted from Sloan Digital Sky Survey i-band images to establish correlations between the SMBH and host galaxy parameters. We test whether the mass of the black hole, MBH, is fundamentally driven by either local or global galaxy properties. We explore correlations between MBH and stellar velocity dispersion sigma, bulge luminosity, bulge mass Sersic index, bulge mean effective surface brightness, luminosity of the galaxy, galaxy stellar mass, maximum circular velocity Vc, galaxy dynamical and effective masses. We verify the tightness of the MBH-sigma relation and find that correlations with other galaxy parameters do not yield tighter trends. We do not find differences in the MBH-sigma relation of barred and unbarred galaxies. The MBH-sigma relation of pseudo-bulges is also coarser and has a different slope than that involving classical bulges. The MBH-bulge mass is not as tight as the MBH-sigma relation, despite the bulge mass proving to be a better proxy of MBH than bulge luminosity. We find a rather poor correlation between MBH and Sersic index suggesting that MBH is not related to the bulge light concentration. The correlations between MBH and galaxy luminosity or mass are not a marked improvement over the MBH sigma relation. If Vc is a proxy for the dark matter halo mass, the large scatter of the MBH-Vc relation then suggests that MBH is more coupled to the baryonic rather than the dark matter. We have tested the need for a third parameter in the MBH scaling relations, through various linear correlations with bulge and galaxy parameters, only to confirm that the fundamental plane of the SMBH is mainly driven by sigma, with a small tilt due to the effective radius. (Abridged)Comment: 32 pages, 18 figures, 6 tables, accepted for publication in MNRA

Effect of Salt on Phosphorylcholine-based Zwitterionic Polymer Brushes.

A quantitative investigation of the responses of surface-grown biocompatible brushes of poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) to different types of salt has been carried out using ellipsometry, quartz crystal microbalance (QCM) measurements, and friction force microscopy. Both cations and anions of varying valency over a wide range of concentrations were examined. Ellipsometry shows that the height of the brushes is largely independent of the ionic strength, confirming that the degree of swelling of the polymer is independent of the ionic character of the medium. In contrast, QCM measurements reveal significant changes in mass and dissipation to the PMPC brush layer, suggesting that ions bind to phosphorylcholine (PC) groups in PMPC molecules, which results in changes in the stiffness of the brush layer, and the binding affinity varies with salt type. Nanotribological measurements made using friction force microscopy show that the coefficient of friction decreases with increasing ionic strength for a variety of salts, supporting the conclusion drawn from QCM measurements. It is proposed that the binding of ions to the PMPC molecules does not change their hydration state, and hence the height of the surface-grown polymeric brushes. However, the balance of the intra- and intermolecular interactions is strongly dependent upon the ionic character of the medium between the hydrated chains, modulating the interactions between the zwitterionic PC pendant groups and, consequently, the stiffness of the PMPC molecules in the brush layer