Towards a unification of HRT and SCOZA. Analysis of exactly solvable mean-spherical and generalized mean-spherical models

The hierarchical reference theory (HRT) and the self-consistent Ornstein-Zernike approximation (SCOZA) are two liquid state theories that both furnish a largely satisfactory description of the critical region as well as the phase coexistence and equation of state in general. Furthermore, there are a number of similarities that suggest the possibility of a unification of both theories. Earlier in this respect we have studied consistency between the internal energy and free energy routes. As a next step toward this goal we here consider consistency with the compressibility route too, but we restrict explicit evaluations to a model whose exact solution is known showing that a unification works in that case. The model in question is the mean spherical model (MSM) which we here extend to a generalized MSM (GMSM). For this case, we show that the correct solutions can be recovered from suitable boundary conditions through either of SCOZA or HRT alone as well as by the combined theory. Furthermore, the relation between the HRT-SCOZA equations and those of SCOZA and HRT becomes transparent.Comment: Minimal correction of some typos found during proof reading. Accepted for publication in Phys. Rev.

Home bias persistence in foreign direct investments

The purpose of this paper is to analyse the issues related to home bias and foreign direct investments (FDIs). We study the role of physical, cultural, and institutional distances from home on FDI decisions taken by corporations to assess whether the globalization of the past two decades has reduced their influence. Using the ‘home bias’ framework from the finance literature and the gravity model from the economics literature, we utilize a large sample of both developed and emerging markets, using FDI flows of 6263 unique bilateral country pairs over a 30-year period. We find strong empirical evidence of persistent home bias in FDI outflows, and we show that not only physical distance but also cultural and institutional similarities between host and source countries remain a decisive factor in foreign corporate investment decisions. We also show that such home bias is persistent over time and is observed around the world

Engineering calculations for communications satellite systems planning

Observed solution times were analyzed for the extended gradient and cyclic coordinate search procedures. The times used in the analysis come from computer runs made during a previously-reported experiment conducted to assess the quality of the solutions to a BSS synthesis problem found by the two search methods. The results of a second experiment with a Fixed Satellite Service (FSS) test problem are also presented. Computational results are summarized for mixed integer programming approaches for solving FSS synthesis problems. A promising heuristic algorithm is described. A synthesis model is discussed for orbital arc allotment optimization. Research plans for the near future are also presented

Dynamics and hysteresis in square lattice artificial spin-ice

Dynamical effects under geometrical frustration are considered in a model for artificial spin ice on a square lattice in two dimensions. Each island of the spin ice has a three-component Heisenberg-like dipole moment subject to shape anisotropies that influence its direction. The model has real dynamics, including rotation of the magnetic degrees of freedom, going beyond the Ising-type models of spin ice. The dynamics is studied using a Langevin equation solved via a second order Heun algorithm. Thermodynamic properties such as the specific heat are presented for different couplings. A peak in specific heat is related to a type of melting-like phase transition present in the model. Hysteresis in an applied magnetic field is calculated for model parameters where the system is able to reach thermodynamic equilibrium.Comment: Revised versio

Energy management in mobile devices with the cinder operating system

We argue that controlling energy allocation is an increasingly useful and important feature for operating systems, especially on mobile devices. We present two new low-level abstractions in the Cinder operating system, reserves and taps, which store and distribute energy for application use. We identify three key properties of control -- isolation, delegation, and subdivision -- and show how using these abstractions can achieve them. We also show how the architecture of the HiStar information-flow control kernel lends itself well to energy control. We prototype and evaluate Cinder on a popular smartphone, the Android G1.National Science Foundation (U.S.) (grant #0831163)National Science Foundation (U.S.) (grant #0846014)Natural Sciences and Engineering Research Council of Canada (NSERC)King Abdullah University of Science and TechnologyMicrosoft ResearchNational Science Foundation (U.S.) (Cybertrust award CNS-0716806)National Science Foundation (U.S.) (POMI (Programmable Open Mobile Internet) 2020 Expedition Grant #0832820)T-Mobile US

Apprehending Joule Thieves with Cinder

Energy is the critical limiting resource to mobile computing devices. Correspondingly, an operating system must track, provision, and ration how applications consume energy. The emergence of third-party application stores and marketplaces makes this concern even more pressing. A third-party application must not deny service through excessive, unforeseen energy expenditure, whether accidental or malicious. Previous research has shown promise in tracking energy usage and rationing it to meet device lifetime goals, but such mechanisms and policies are still nascent, especially regarding user interaction. We argue for a new operating system, called Cinder, which builds on top of the HiStar OS. Cinder's energy awareness is based on hierarchical capacitors and task profiles. We introduce and explore these abstractions, paying particular attention to the ways in which policies could be generated and enforced in a dynamic system

Advanced imaging and tissue engineering of the human limbal epithelial stem cell niche

The limbal epithelial stem cell niche provides a unique, physically protective environment in which limbal epithelial stem cells reside in close proximity with accessory cell types and their secreted factors. The use of advanced imaging techniques is described to visualize the niche in three dimensions in native human corneal tissue. In addition, a protocol is provided for the isolation and culture of three different cell types, including human limbal epithelial stem cells from the limbal niche of human donor tissue. Finally, the process of incorporating these cells within plastic compressed collagen constructs to form a tissue-engineered corneal limbus is described and how immunohistochemical techniques may be applied to characterize cell phenotype therein

Design and Implementation of a State-Driven Operating System for Highly Reconfigurable Sensor Networks

Due to the low-cost and low-power requirement in an individual sensor node, the available computing resources turn out to be very limited like small memory footprint and irreplaceable battery power. Sensed data fusion might be needed before being transmitted as a tradeoff between procession and transmission in consideration of saving power consumption. Even worse, the application program needs to be complicated enough to be self-organizing and dynamically reconfigurable because changes in an operating environment continue even after deployment. State-driven operating system platform offers numerous benefits in this challenging situation. It provides a powerful way to accommodate complex reactive systems like diverse wireless sensor network applications. The memory usage can be bounded within a state transition table. The complicated issues like concurrency control and asynchronous event handling capabilities can be easily achieved in a well-defined behavior of state transition diagram. In this paper, we present an efficient and effective design of the state-driven operating system for wireless sensor nodes. We describe that the new platform can operate in an extremely resource constrained situation while providing the desired concurrency, reactivity, and reconfigurability. We also compare the executing results after comparing some benchmark test results with those on TinyOS

Teaching High-Value Pronunciation Features: Contrastive Stress for Intermediate Learners

Pronunciation features are not equal in how they affect listeners’ ability to understand. Some are low value, while others are high value. This study explores whether contrastive stress is high value. Previous research has shown that identification of contrastive stress is learnable (Pennington & Ellis, 2000), and that explicit teaching about contrastive stress patterns can improve production for advanced learners (Hahn, 2002; Muller Levis & Levis, 2012). To test whether instruction on contrastive stress improved comprehensibility and fluency in spontaneous speech, we developed a 3-week class for intermediate ESL learners, whose pre- and posttest productions were rated by native listeners. Ratings for fluency showed no improvement. Ratings for comprehensibility significantly improved for the experimental group while control participants showed no improvement. Improvement resulted both from better contrastive stress and greater comfort with producing grammatical frames to express the contrasts. The article concludes by discussing the importance of high-value pronunciation features for improved comprehensibility