Theory of Dynamic Stripe Induced Superconductivity

Since the recently reported giant isotope effect on T* [1] could be consistently explained within an anharmonic spin-charge-phonon interaction model, we consider here the role played by stripe formation on the superconducting properties within the same model. This is a two-component scenario and we recast its basic elements into a BCS effective Hamiltonian. We find that the stripe formation is vital to high-Tc superconductivity since it provides the glue between the two components to enhance Tc to the unexpectedly large values observed experimentally.Comment: 7 pages, 2 figure

Predictions of the causal entropic principle for environmental conditions of the universe

The causal entropic principle has been proposed as a superior alternative to the anthropic principle for understanding the magnitude of the cosmological constant. In this approach, the probability to create observers is assumed to be proportional to the entropy production \Delta S in a maximal causally connected region -- the causal diamond. We improve on the original treatment by better quantifying the entropy production due to stars, using an analytic model for the star formation history which accurately accounts for changes in cosmological parameters. We calculate the dependence of \Delta S on the density contrast Q=\delta\rho/\rho, and find that our universe is much closer to the most probable value of Q than in the usual anthropic approach and that probabilities are relatively weakly dependent on this amplitude. In addition, we make first estimates of the dependence of \Delta S on the baryon fraction and overall matter abundance. Finally, we also explore the possibility that decays of dark matter, suggested by various observed gamma ray excesses, might produce a comparable amount of entropy to stars.Comment: RevTeX4, 13pp, 10 figures; v2. clarified introduction, added ref

A Sunyaev-Zel'dovich Effect Survey for High Redshift Clusters

Interferometric observations of the Sunyaev-Zel'dovich Effect (SZE) toward clusters of galaxies provide sensitive cosmological probes. We present results from 1 cm observations (at BIMA and OVRO) of a large, intermediate redshift cluster sample. In addition, we describe a proposed, higher sensitivity array which will enable us to survey large portions of the sky. Simulated observations indicate that we will be able to survey one square degree of sky per month to sufficient depth that we will detect all galaxy clusters more massive than 2x10^{14} h^{-1}_{50}M_\odot, regardless of their redshift. We describe the cluster yield and resulting cosmological constraints from such a survey.Comment: 7 pages, 6 figures, latex, contribution to VLT Opening Symposiu

Cooperation, Proximity, and Social Innovation: Three Ingredients for Industrial Medium-Sized Towns’ Renewal?

Over several decades, medium-sized industrial towns have suffered from a combination of economic and political processes: Deindustrialization, metropolization, and withdrawal of public services. After two decades in which they have been somewhat neglected (in favor of metropolises), there have recently been State and European public policies aimed at them. Medium-sized cities are not homogeneous and present several trajectories. Based on quantitative approach in France, we highlight the very diverse socio-economic dynamics of French medium-sized industrial towns. Thus, far from widespread decline or shrinking dynamics, some of these cities are experiencing an economic rebound. This is the case of Romans-sur-Isère, a medium-sized town located in the south-east of France. Focusing our qualitative analyze on this city, we try to understand this type of process. In this medium-sized town, former capital of the shoe industry, local stakeholders, private, and public try to support a productive renewal. The results of our case study highlight the role that cooperation, spatial and organizational proximity, and social innovation could play in the renewal of productive economy in medium-sized industrial towns. Even if the economic situation remains difficult for many medium-sized cities in France as in Europe, we argue that they could have a productive future making and ultimately take advantages of their “medium-sized” attributes. Over several decades, medium-sized industrial towns have suffered from a combination of economic and political processes: Deindustrialization, metropolization, and withdrawal of public services. After two decades in which they have been somewhat neglected (in favor of metropolises), there have recently been State and European public policies aimed at them. Medium-sized cities are not homogeneous and present several trajectories. Based on quantitative approach in France, we highlight the very diverse socio-economic dynamics of French medium-sized industrial towns. Thus, far from widespread decline or shrinking dynamics, some of these cities are experiencing an economic rebound. This is the case of Romans-sur-Isère, a medium-sized town located in the south-east of France. Focusing our qualitative analyze on this city, we try to understand this type of process. In this medium-sized town, former capital of the shoe industry, local stakeholders, private, and public try to support a productive renewal. The results of our case study highlight the role that cooperation, spatial and organizational proximity, and social innovation could play in the renewal of productive economy in medium-sized industrial towns. Even if the economic situation remains difficult for many medium-sized cities in France as in Europe, we argue that they could have a productive future making and ultimately take advantages of their “medium-sized” attributes. &nbsp

The Relationship Between the Number of Shots and the Quality of Gamma Knife Radiosurgeries

Radiosurgery is a non-invasive alternative to brain surgery that uses a single focused application of high radiation to destroy intracerebral target tissues. A Gamma Knife delivers such treatments by using 201 cylindrically collimated cobalt-60 sources that are arranged in a hemispherical pattern and aimed to a common focal point. The accumulation of radiation at the focal point, called a \shot due to the spherical nature of the dose distribution, is used to ablate (or destroy) target tissue in the brain. If the target is small and spherical, it is easily treated by choosing one of four available collimators (4, 8, 14, or 18 mm). For large, irregular targets, multiple shots are typically required to treat the entire lesion, and the process of determining the optimal arrangement and number of shots is complex. In this research, fast simulated annealing and a novel objective function are used to investigate the relationship between the number of shots and the quality of the resulting treatment. Sets of 5, 10, 25, 50, and an unrestricted number of shots are studied for an arteriovenous malformation (AVM). As the shot limit increases the following improvements in plan quality are observed: the conformity of the prescription isodose line increases, the lesion dose becomes more homogeneous, and an increase use of smaller collimators to deposit dose. Large improvements in plan quality are realized by increasing the number of shots from 5 to 50, and to achieve a similar magnitude of improvement past 50 requires an increase over 1500 shots for the complex lesion investigated. This observation suggests that it is clinically valuable to improve the Gamma Knife\u27s delivery capabilities so that 50 shot treatments are possible

Constraints on Cosmological Parameters from Future Galaxy Cluster Surveys

We study the expected redshift evolution of galaxy cluster abundance between 0 < z < 3 in different cosmologies, including the effects of the cosmic equation of state parameter w=p/rho. Using the halo mass function obtained in recent large scale numerical simulations, we model the expected cluster yields in a 12 deg^2 Sunyaev-Zeldovich Effect (SZE) survey and a deep 10^4 deg^2 X-ray survey over a wide range of cosmological parameters. We quantify the statistical differences among cosmologies using both the total number and redshift distribution of clusters. Provided that the local cluster abundance is known to a few percent accuracy, we find only mild degeneracies between w and either Omega_m or h. As a result, both surveys will provide improved constraints on Omega_m and w. The Omega_m-w degeneracy from both surveys is complementary to those found either in studies of CMB anisotropies or of high-redshift Supernovae (SNe). As a result, combining these surveys together with either CMB or SNe studies can reduce the statistical uncertainty on both w and Omega_m to levels below what could be obtained by combining only the latter two data sets. Our results indicate a formal statistical uncertainty of about 3% (68% confidence) on both Omega_m and w when the SZE survey is combined with either the CMB or SN data; the large number of clusters in the X-ray survey further suppresses the degeneracy between w and both Omega_m and h. Systematics and internal evolution of cluster structure at the present pose uncertainties above these levels. We briefly discuss and quantify the relevant systematic errors. By focusing on clusters with measured temperatures in the X-ray survey, we reduce our sensitivity to systematics such as non-standard evolution of internal cluster structure.Comment: ApJ, revised version. Expanded discussion of systematics; Press-Schechter mass function replaced by fit from simulation