Exact Site Percolation Thresholds Using the Site-to-Bond and Star-Triangle Transformations

I construct a two-dimensional lattice on which the inhomogeneous site percolation threshold is exactly calculable and use this result to find two more lattices on which the site thresholds can be determined. The primary lattice studied here, the ``martini lattice'', is a hexagonal lattice with every second site transformed into a triangle. The site threshold of this lattice is found to be $0.764826...$, while the others have $0.618034...$ and $1/\sqrt{2}$. This last solution suggests a possible approach to establishing the bound for the hexagonal site threshold, $p_c<1/\sqrt{2}$. To derive these results, I solve a correlated bond problem on the hexagonal lattice by use of the star-triangle transformation and then, by a particular choice of correlations, solve the site problem on the martini lattice.Comment: 12 pages, 10 figures. Submitted to Physical Review

A hybrid metal/semiconductor electron pump for quantum metrology

Electron pumps capable of delivering a current higher than 100pA with sufficient accuracy are likely to become the direct mise en pratique of the possible new quantum definition of the ampere. Furthermore, they are essential for closing the quantum metrological triangle experiment which tests for possible corrections to the quantum relations linking e and h, the electron charge and the Planck constant, to voltage, resistance and current. We present here single-island hybrid metal/semiconductor transistor pumps which combine the simplicity and efficiency of Coulomb blockade in metals with the unsurpassed performances of silicon switches. Robust and simple pumping at 650MHz and 0.5K is demonstrated. The pumped current obtained over a voltage bias range of 1.4mV corresponds to a relative deviation of 5e-4 from the calculated value, well within the 1.5e-3 uncertainty of the measurement setup. Multi-charge pumping can be performed. The simple design fully integrated in an industrial CMOS process makes it an ideal candidate for national measurement institutes to realize and share a future quantum ampere

Connecting the timescales in picosecond remagnetization experiments

In femtosecond demagnetization experiments, one gains access to the elementary relaxation mechanisms of a magnetically ordered spin system on a time scale of 100 fs. Following these experiments, we report a combined micromagnetic and experimental study that connects the different regimes known from all-optical pump-probe experiments by employing a simple micromagnetic model. We identify spin-wave packets on the nanometer scale that contribute to the remagnetization process on the intermediate time scale between single-spin relaxation and collective precession.Comment: 12 pages, 3 figures, submitted to Phys. Rev. Lett, changes made with regard to review proces

The Emerging QCD Frontier: The Electron Ion Collider

The self-interactions of gluons determine all the unique features of QCD and lead to a dominant abundance of gluons inside matter already at moderate $x$. Despite their dominant role, the properties of gluons remain largely unexplored. Tantalizing hints of saturated gluon densities have been found in $e$+p collisions at HERA, and in d+Au and Au+Au collisions at RHIC. Saturation physics will have a profound influence on heavy-ion collisions at the LHC. But unveiling the collective behavior of dense assemblies of gluons under conditions where their self-interactions dominate will require an Electron-Ion Collider (EIC): a new facility with capabilities well beyond those In this paper I outline the compelling physics case for $e$+A collisions at an EIC and discuss briefly the status of machine design concepts. of any existing accelerator.Comment: 11 pages, 9 figures, prepared for 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008), Jaipur, India, 4-10 Feb. 200

Inclusion of Experimental Information in First Principles Modeling of Materials

We propose a novel approach to model amorphous materials using a first principles density functional method while simultaneously enforcing agreement with selected experimental data. We illustrate our method with applications to amorphous silicon and glassy GeSe$_2$. The structural, vibrational and electronic properties of the models are found to be in agreement with experimental results. The method is general and can be extended to other complex materials.Comment: 11 pages, 8 PostScript figures, submitted to J. Phys.: Condens. Matter in honor of Mike Thorpe's 60th birthda

Electrorotation of a pair of spherical particles

We present a theoretical study of electrorotation (ER) of two spherical particles under the action of a rotating electric field. When the two particles approach and finally touch, the mutual polarization interaction between the particles leads to a change in the dipole moment of the individual particle and hence the ER spectrum, as compared to that of the well-separated particles. The mutual polarization effects are captured by the method of multiple images. From the theoretical analysis, we find that the mutual polarization effects can change the characteristic frequency at which the maximum angular velocity of electrorotation occurs. The numerical results can be understood in the spectral representation theory.Comment: Minor revisions; accepted by Phys. Rev.

Resilience to cope with climate change in urban areas - A multisectorial approach focusing on water - The RESCCUE project

This is the final version. Available on open access from MDPI via the DOI in this recordThe RESCCUE Project is an H2020 research project that aims to help cities around the world to become more resilient to physical, social, and economic challenges, using the water sector as the central point of the approach. RESCCUE will generate models and tools to bring this objective to practice, while delivering a framework enabling city resilience assessment, planning and management. This will be achieved by integrating software tools, methods, and new knowledge related to the detailed urban services performance into novel and promising loosely coupled models (integrated models), multi-risk assessment method, and a comprehensive resilience platform. These tools will allow urban resilience assessment from a multisectorial approach, for current and future climate change scenarios, including multiple hazards and cascading effects. The RESCCUE approach will be implemented in three EU cities (Barcelona, Bristol, and Lisbon) and, with the support of UN-Habitat, disseminate their results among other cities belonging to major international networks. The aim of this paper is to present the main goals of this project, as well as the approach followed and the main expected results after the four years of implementation, so other cities around the world can use the RESCCUE approach to increase their resilience.The RESCCUE Project (RESilience to cope with Climate Change in Urban arEas—a multisectorial approach focusing on water) has received funding from European Commission by means of Horizon 2020, the EU Framework Program for Research and Innovation, under Grant Agreement No. 700174

The sustainability of desalination as a remedy to the water crisis in the agriculture sector: An analysis from the climate-water-energy-food nexus perspective

This is the final version. Available on open access from Elsevier via the DOI in this recordData Availability: No data was used for the research described in the article.Over the years, desalination has become integral to water resources management, primarily in coastal semi-arid to arid regions. While desalinated seawater has mainly been supplied to municipal and high-revenue industries, the agriculture sector faces increasing irrigation demands, making it a potential user. This review assesses the sustainability of using desalinated seawater for irrigation, shedding light on its limitations and potential. Using desalinated water for irrigation presents challenges, including its high energy consumption, potential contribution to climate change, and agronomy-related concerns. However, evidence suggests that these challenges can be addressed effectively through tailor-fitted strategies. That said, conventional binary decision-making paradigms that label practices as good or bad and focus on a singular, isolated aspect are insufficient for evaluating the sustainability of desalination due to the complex and interconnected nature of the issues involved. To overcome this, the climate-water-energy-food (CWEF) nexus concept is proposed as a comprehensive framework for sustainability assessment. Adopting the CWEF nexus approach allows for a better understanding of the potential challenges associated with using desalinated water for irrigation, encompassing social, economic and environmental concerns. To ensure effective management of these challenges, it is crucial to tailor desalination projects to specific regional conditions and employ either prophylactic or corrective strategies. By embracing the CWEF nexus approach, informed decisions can be made regarding the future utilization of desalinated water for irrigation, contributing to broader sustainability goals

Jet Quenching in Heavy Ion Collisions

This review article was prepared for the Landolt-Boernstein volume on Relativisitc Heavy Ion Physics.Comment: Review articel accepted for publication in the Landolt-Boernstein Handbook of Physics, ed. R. Stock. 41 pages LaTex, 7 eps-figure