Mapping of 2+1-dimensional Kardar-Parisi-Zhang growth onto a driven lattice gas model of dimer

We show that a 2+1 dimensional discrete surface growth model exhibiting Kardar-Parisi-Zhang (KPZ) class scaling can be mapped onto a two dimensional conserved lattice gas model of directed dimers. In case of KPZ height anisotropy the dimers follow driven diffusive motion. We confirm by numerical simulations that the scaling exponents of the dimer model are in agreement with those of the 2+1 dimensional KPZ class. This opens up the possibility of analyzing growth models via reaction-diffusion models, which allow much more efficient computer simulations.Comment: 5 pages, 4 figures, final form to appear in PR

Ordering intermetallic alloys by ion irradiation: a way to tailor magnetic media

Combining He ion irradiation and thermal mobility below 600K, we both trigger and control the transformation from chemical disorder to order in thin films of an intermetallic ferromagnet (FePd). Kinetic Monte Carlo simulations show how the initial directional short range order determines order propagation. Magnetic ordering perpendicular to the film plane was achieved, promoting the initially weak magnetic anisotropy to the highest values known for FePd films. This post-growth treatment should find applications in ultrahigh density magnetic recording.Comment: 7 pages, 3 Figure

Supervised Learning Algorithms to Extract Market Sentiment: An Application in the UK Commercial Real Estate Market

Sentiment analysis has become a key area of research in economics and finance with methods evolving from traditional survey-based analysis to computational linguistic techniques. New developments in data handling and analysis have allowed extracting sentiment from vast amounts of written documents. However, these methods depend heavily on the existence of training and test data sets. The choice of training data is critical in such applications. We show a novel application from a unique market – commercial real estate. There are several unique attributes of the real estate market that makes such analysis critical for insightful market intelligence. In the absence of training data sets for the UK commercial real estate (CRE) market, we propose the use of Amazon book reviews for real estate related products. Our analysis has shown, that the use of more than 200,000 book reviews, can train different supervised learning algorithms, which in turn, can capture the sentiment and more importantly, it can help predict the direct commercial real estate market trends

Influence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-delta thin films

Low-angle grain boundaries with misorientation angles theta < 5 degrees in optimally doped thin films of YBCO are investigated by magnetooptical imaging. By using a numerical inversion scheme of Biot-Savart's law the critical current density across the grain boundary can be determined with a spatial resolution of about 5 micrometers. Detailed investigation of the spatially resolved flux density and current density data shows that the current density across the boundary varies with varying local flux density. Combining the corresponding flux and current pattern it is found that there exists a universal dependency of the grain boundary current on the local flux density. A change in the local flux density means a variation in the flux line-flux line distance. With this knowledge a model is developped that explains the flux-current relation by means of magnetic vortex-vortex interaction.Comment: 7 pages, 14 figure

Strongly linked current flow in polycrystalline forms of the new superconductor MgB2

The discovery of superconductivity at 39 K in MgB2[1] raises many issues. One of the central questions is whether this new superconductor resembles a high-temperature-cuprate superconductor or a low-temperature metallic superconductor in terms of its current carrying characteristics in applied magnetic fields. In spite of the very high transition temperatures of the cuprate superconductors, their performance in magnetic fields has several drawbacks[2]. Their large anisotropy restricts high bulk current densities to much less than the full magnetic field-temperature (H-T) space over which superconductivity is found. Further, weak coupling across grain boundaries makes transport current densities in untextured polycrystalline forms low and strongly magnetic field sensitive[3,4]. These studies of MgB2 address both issues. In spite of the multi-phase, untextured, nano-scale sub-divided nature of our samples, supercurrents flow throughout without the strong sensitivity to weak magnetic fields characteristic of Josephson-coupled grains[3]. Magnetization measurements over nearly all of the superconducting H-T plane show good temperature scaling of the flux pinning force, suggestive of a current density determined by flux pinning. At least two length scales are suggested by the magnetization and magneto optical (MO) analysis but the cause of this seems to be phase inhomogeneity, porosity, and minority insulating phase such as MgO rather than by weakly coupled grain boundaries. Our results suggest that polycrystalline ceramics of this new class of superconductor will not be compromised by the weak link problems of the high temperature superconductors, a conclusion with enormous significance for applications if higher temperature analogs of this compound can be discovered

Housing Affordability in a Resource Rich Economy: The Case of Kuwait

This paper seeks to test the impact of new policies introduced to the Kuwaiti housing market to improve affordability. In 2008, the Kuwaiti parliament introduced two policies: a tax on empty lands and the other on forbidding companies to own or develop residential lands or houses. We constructed the housing affordability index and the price-to-income multiplier to measure housing affordability performance. We used observations from 2004 until 2017. We found that affordability has worsened over time regardless of the new policies introduced in 2008. Housing in Kuwait became “severely unaffordable” (equivalent to London in the U.K., San Diego in U.S. and Toronto in Canada). Even with its unique condition, as a rich country, small population and availability of white land and other resources, the affordability worsened over time. Introducing new policies without solving the central issue of housing supply challenges seems not worth it. This paper is the first of its kind on the Kuwait housing market, and it provides a valuable foundation for future research on this market and similar markets in the region

HIV-1 Drug Resistance Emergence among Breastfeeding Infants Born to HIV-Infected Mothers during a Single-Arm Trial of Triple-Antiretroviral Prophylaxis for Prevention of Mother-To-Child Transmission: A Secondary Analysis

Analysis of a substudy of the Kisumu breastfeeding trial by Clement Zeh and colleagues reveals the emergence of HIV drug resistance in HIV-positive infants born to HIV-infected mothers treated with antiretroviral drugs

Unilateral Palmar Callus and Irritant Hand Eczema – Underreported Signs of Dependency on Crutches

Leg amputees who can’t use prostheses and patients with arthritis are often dependent on crutches. Their chronic use can exert significant friction forces. The palmar skin will respond by forming a hyperkeratotic callus. We report for the first time unilateral palmar callus formation caused by friction from using crutches. Another possible adverse effect is the triggering of irritant contact dermatitis by the handholes of crutches. We report two cases with hand dermatitis due to the chronic dependence on crutches and discuss treatment options

Laser induced sponge-like Si in Si-rich oxides for photovoltaics

We show that a sponge-like structure of interconnected Si nanowires embedded in a dielectric matrix can be obtained by laser annealing of silicon rich oxides (SRO). Due to quantum confinement, the large bandgap displayed by these percolated nanostructures can be utilized as a tandem stage in 3rd generation thin-film solar cells. Well passivated by the SiO2 dielectric matrix, they are expected to overcome the difficulty of carrier separation encountered in the case of isolated crystalline quantum dots. In this study PECVD grown SRO were irradiated by a cw Ar+ laser. Raman spectroscopy has been used to assess the crystallinity of the Si nanostructures and thus to optimize the annealing conditions as dwell times and power densities. In addition, Si plasmon imaging in the transmission electron microscope was applied to identify the sponge-like structure of phase-separated silicon. © 2013 Optical Society of America