Consequences of the Factorization Hypothesis in pbar p, pp, gamma p and gamma gamma Collisions

Using an eikonal analysis, we examine the validity of the factorization theorem for nucleon-nucleon, gamma p and gamma gamma collisions. As an example, using the additive quark model and meson vector dominance, we directly show that for all energies and values of the eikonal, that the factorization theorem sigma_{nn}/sigma_{gamma p} = sigma_{gamma p}/sigma_{gamma gamma} holds. We can also compute the survival probability of large rapidity gaps in high energy pbar p and pp collisions. We show that the survival probabilities are identical (at the same energy) for gamma p and gamma gamma collisions, as well as for nucleon-nucleon collisions. We further show that neither the factorization theorem nor the reaction-independence of the survival probabilities depends on the assumption of an additive quark model, but, more generally, depends on the opacity of the eikonal being independent of whether the reaction is n-n, gamma p or gamma gamma.Comment: 8 pages, Revtex, no figures. Expanded discussion, minor correction

Analytic models and forward scattering from accelerator to cosmic-ray energies

Analytic models for hadron-hadron scattering are characterized by analytical parametrizations for the forward amplitudes and the use of dispersion relation techniques to study the total cross section $\sigma_{tot}$ and the $\rho$ parameter. In this paper we investigate four aspects related to the application of the model to $pp$ and $\bar{p}p$ scattering, from accelerator to cosmic-ray energies: 1) the effect of different estimations for $\sigma_{tot}$ from cosmic-ray experiments; 2) the differences between individual and global (simultaneous) fits to $\sigma_{tot}$ and $\rho$; 3) the role of the subtraction constant in the dispersion relations; 4) the effect of distinct asymptotic inputs from different analytic models. This is done by using as a framework the single Pomeron and the maximal Odderon parametrizations for the total cross section. Our main conclusions are the following: 1) Despite the small influence from different cosmic-ray estimations, the results allow us to extract an upper bound for the soft pomeron intercept: $1 + \epsilon = 1.094$; 2) although global fits present good statistical results, in general, this procedure constrains the rise of $\sigma_{tot}$; 3) the subtraction constant as a free parameter affects the fit results at both low and high energies; 4) independently of the cosmic-ray information used and the subtraction constant, global fits with the odderon parametrization predict that, above $\sqrt s \approx 70$ GeV, $\rho_{pp}(s)$ becomes greater than $\rho_{\bar{p}p}(s)$, and this result is in complete agreement with all the data presently available. In particular, we infer $\rho_{pp} = 0.134 \pm 0.005$ at $\sqrt s = 200$ GeV and $0.151 \pm 0.007$ at 500 GeV (BNL RHIC energies).Comment: 16 pages, 7 figures, aps-revtex, wording changes, corrected typos, to appear in Physical Review

Cinétiques de biodégradation par boues activées de la matière organique soluble d'un effluent synthétique

L'approche expérimentale choisie pour cette étude a eu pour objet de mesurer en conditions batch, les cinétiques d'élimination de la demande chimique en oxygène soluble d'un effluent synthétique mis en contact avec des boues activées d'origine différente. Les essais conduits en laboratoire ont été réalisés en faisant varier le rapport So/Xo (mg de DCO initiale par mg de matières volatiles initiales) telles que les concentrations en So et en Xo correspondent aux concentrations en DCO soluble (DCOs) et en matières volatiles (MV) rencontrées sur les stations d'épuration. Les essais ont été effectués sous aération continue à 20 °C en mettant en contact l'effluent synthétique et de la boue activée prélevée depuis 24 h et stockée à 4 °C dans l'attente de l'essai. De ce fait, la valeur de So mesurée au début de l'essai représente la concentration en DCO amenée par l'effluent synthétique (Seff) et celle amenée par l'inoculum de boue activée (Sb) représentant selon les essais de 5 à 70 % de la DCO de l'essai. Les profils de cinétique d'élimination de la DCO soluble obtenus pour différentes conditions d'essai s'ajustent, selon les valeurs de So/Xo (So/Xo variant de 0,15 à 2,17 ) à une fonction du premier ordre par rapport au substrat ou à une fonction sigmoïde. Le type de fonction cinétique d'élimination est également contrôlé par la proportion de la DCO amenée par l'inoculum.The conventional activated sludge process used for wastewater treatment removes from 80 to 95% of the total organic matter. However, a quantity of "not well identified" (particular, colloidal and soluble) organic matter is always present in the treated effluent. Reducing this residual (and improving the treatment efficiency) requires knowledge of the origin of that organic matter and especially to determine the fraction originating from the influent and the fraction generated by the biomass.This research has been conducted in batch conditions and studies the soluble COD (CODs) removal kinetics of a synthetic effluent (casein + starch + acetate + mineral salts), in contact with different activated sludge originating from six different wastewater treatment plants (loads varying from 0.06 to 1.14 kg BOD[inf]5/kg VSS. d).Experiments have been conducted with different So/Xo values (ratio between CODs initial concentration and VSS initial concentration) in order that these values correspond to the CODs and VSS values found in the plants.In accordance with GRAU et al. (1975), CECH and CHUDOBA (1983), PITTER and CHUDOBA (1990), CHUDOBA et al (1992), the So/Xo ratio is a fundamental parameter governing the kinetics reactions.Experiments have been conducted under continuous aeration at 20°C where the synthetic wastewater (500 ml) is in contact with activated sludge (200 ml) collected 24 h before and stored at 4°C until the batch is started. In this manner, the initial So is due to the CODs of the synthetic effluent (So eff=197 mg/l) and to the CODs originating from the sludge (5 to 70% of the initial CODs). The initial VSS concentration (Xo) is between 0.6 and 2.5 g/l. Kinetics of CODs removal are simulated by two functions: the first order function, where the initial rate is the maximal, and the sigmoidal function where the maximal rate is reached after a lag time (3 to 8 h).Concerning the first order functions, the degradation rate is faster when the ratio is low (So/Xo lower than 0.44). This is not the case for the sigmoidal functions. In the results of this study, the residual of COD is always lower when the degradation kinetic follows the exponential model.Our experiments show that the type of degradation kinetics (first order or sigmoidal) is not only controlled by the So/Xo parameter but also by the proportion of CODs brought by the sludge and that parameter can play a determinant role.When the proportion of CODs brought by the sludge is very large (between 41% to 46%) the degradation reactions follow the sigmoidal type. These results can possibly be explained by the low biodegradability of the polymers or molecules originating from the inoculum which has been stored during 24 h, or by the low activity of the biomass after 24 h of storage on the biodegradation of the soluble organic matte

New physics, the cosmic ray spectrum knee, and pppp cross section measurements

We explore the possibility that a new physics interaction can provide an explanation for the knee just above $10^6$ GeV in the cosmic ray spectrum. We model the new physics modifications to the total proton-proton cross section with an incoherent term that allows for missing energy above the scale of new physics. We add the constraint that the new physics must also be consistent with published $pp$ cross section measurements, using cosmic ray observations, an order of magnitude and more above the knee. We find that the rise in cross section required at energies above the knee is radical. The increase in cross section suggests that it may be more appropriate to treat the scattering process in the black disc limit at such high energies. In this case there may be no clean separation between the standard model and new physics contributions to the total cross section. We model the missing energy in this limit and find a good fit to the Tibet III cosmic ray flux data. We comment on testing the new physics proposal for the cosmic ray knee at the Large Hadron Collider.Comment: 17 pages, 4 figure

Morphological Classification of Galaxies by Shapelet Decomposition in the Sloan Digital Sky Survey II: Multiwavelength Classification

We describe the application of the `shapelet' linear decomposition of galaxy images to multi-wavelength morphological classification using the $u,g,r,i,$ and $z$-band images of 1519 galaxies from the Sloan Digital Sky Survey. We utilize elliptical shapelets to remove to first-order the effect of inclination on morphology. After decomposing the galaxies we perform a principal component analysis on the shapelet coefficients to reduce the dimensionality of the spectral morphological parameter space. We give a description of each of the first ten principal component's contribution to a galaxy's spectral morphology. We find that galaxies of different broad Hubble type separate cleanly in the principal component space. We apply a mixture of Gaussians model to the 2-dimensional space spanned by the first two principal components and use the results as a basis for classification. Using the mixture model, we separate galaxies into three classes and give a description of each class's physical and morphological properties. We find that the two dominant mixture model classes correspond to early and late type galaxies, respectively. The third class has, on average, a blue, extended core surrounded by a faint red halo, and typically exhibits some asymmetry. We compare our method to a simple cut on $u-r$ color and find the shapelet method to be superior in separating galaxies. Furthermore, we find evidence that the $u-r=2.22$ decision boundary may not be optimal for separation between early and late type galaxies, and suggest that the optimal cut may be $u-r \sim 2.4$.Comment: 42 pages, 18 figs, revised version in press at AJ. Some modification to the technique, more discussion, addition/deletion/modification of several figures, color figures have been added. A high resolution version may be obtained at http://bllac.as.arizona.edu/~bkelly/shapelets/shapelets_ugriz.ps.g

Smart Grid Economics: Policy Guidance through Competitive Simulation

Sustainable energy systems of the future will need more than efficient, clean, low-cost, renewable energy sources; they will also need efficient price signals that motivate sustainable energy consumption as well as a better real-time alignment of energy demand and supply

Radial HI Profiles at the Periphery of Galactic Disks: The Role of Ionizing Background Radiation

Observations of neutral hydrogen in spiral galaxies reveal a sharp cutoff in the radial density profile at some distance from the center. Using 22 galaxies with known HI distributions as an example, we discuss the question of whether this effect can be associated exclusively with external ionizing radiation, as is commonly assumed. We show that before the surface density reaches $\sigma_{\textrm{HI}}\le 0.5 {\cal M}_\odot/{\textrm {pc}}^2$(the same for galaxies of different types), it is hard to expect the gas to be fully ionized by background radiation. For two of 13 galaxies with a sharp drop in the HI profile, the "steepening" can actually be caused by ionization. At the same time, for the remaining galaxies, the observed cutoff in the radial HI profile is closer to the center than if it was a consequence of ionization by background radiation and, therefore, it should be caused by other factors.Comment: 15 pages, 6 figure

Global Star Formation Rates in Disk Galaxies and Circumnuclear Starbursts from Cloud Collisions

We invoke star formation triggered by cloud-cloud collisions to explain global star formation rates of disk galaxies and circumnuclear starbursts. Previous theories based on the growth rate of gravitational perturbations ignore the dynamically important presence of magnetic fields. Theories based on triggering by spiral density waves fail to explain star formation in systems without such waves. Furthermore, observations suggest gas and stellar disk instabilities are decoupled. Following Gammie, Ostriker & Jog (1991), the cloud collision rate is set by the shear velocity of encounters with initial impact parameters of a few tidal radii, due to differential rotation in the disk. This, together with the effective confinement of cloud orbits to a two dimensional plane, enhances the collision rate above that for particles in a three dimensional box. We predict Sigma_{SFR}(R) proportional to Sigma_{gas} Omega (1-0.7 beta). For constant circular velocity (beta = 0), this is in agreement with recent observations (Kennicutt 1998). We predict a B-band Tully-Fisher relation: L_{B} proportional to v_{circ}^{7/3}, also consistent with observations. As additional tests, we predict enhanced star formation in regions with relatively high shear rates, and lower star formation efficiencies in clouds of higher mass.Comment: 27 pages including 3 figures and 2 tables. Accepted to ApJ. Expanded statistical analysis of cloud SF efficiency test. Stylistic changes. Data for figures available electronically at http://astro.berkeley.edu/~jt/disksfr.htm

A Multi-Agent Energy Trading Competition

The energy sector will undergo fundamental changes over the next ten years. Prices for fossil energy resources are continuously increasing, there is an urgent need to reduce CO2 emissions, and the United States and European Union are strongly motivated to become more independent from foreign energy imports. These factors will lead to installation of large numbers of distributed renewable energy generators, which are often intermittent in nature. This trend conflicts with the current power grid control infrastructure and strategies, where a few centralized control centers manage a limited number of large power plants such that their output meets the energy demands in real time. As the proportion of distributed and intermittent generation capacity increases, this task becomes much harder, especially as the local and regional distribution grids where renewable energy generators are usually installed are currently virtually unmanaged, lack real time metering and are not built to cope with power flow inversions (yet). All this is about to change, and so the control strategies must be adapted accordingly. While the hierarchical command-and-control approach served well in a world with a few large scale generation facilities and many small consumers, a more flexible, decentralized, and self-organizing control infrastructure will have to be developed that can be actively managed to balance both the large grid as a whole, as well as the many lower voltage sub-grids. We propose a competitive simulation test bed to stimulate research and development of electronic agents that help manage these tasks. Participants in the competition will develop intelligent agents that are responsible to level energy supply from generators with energy demand from consumers. The competition is designed to closely model reality by bootstrapping the simulation environment with real historic load, generation, and weather data. The simulation environment will provide a low-risk platform that combines simulated markets and real-world data to develop solutions that can be applied to help building the self-organizing intelligent energy grid of the future