Optimal radio resources and transmission formats assignment in OFDMA systems

The problem of assigning radio resources and transmission formats to users in the downlink of an OFDMA network is addressed. In particular, a single cell environment with a realistic interference model and a margin adaptive approach is considered, i.e., the aim is of minimizing the total transmission power while maintaining a certain given rate for each user. The computational complexity issues of the problem are discussed, and an approximation analysis is presented. Heuristic approaches, based on rounding techniques and graph models, are also proposed. Computational experiences show that, in a comparison with a commercial state-of-the-art optimization solver and with alternatives from the literature, the proposed algorithms are effective in terms of solution quality and CPU times.     

Impact of Ge-Sb-Te compound engineering on the set operation performance in phase-change memories

The phase-change memory (PCM) technology is considered as one of the most attractive non-volatile memory concepts for next generation data storage. It relies on the ability of a chalcogenide material belonging to the Ge-Sb-Te compound system to reversibly change its phase between two stable states, namely the poly-crystalline low-resistive state and the amorphous high-resistive state, allowing the storage of the logical bit. A careful study of the phase-change material properties in terms of the set operation performance, the program window and the electrical switching parameters as a function of composition is very attractive in order to enlarge the possible PCM application spectrum. Concerning the set performance, a crystallization kinetics based interpretation of the observed behavior measured on different Ge-Sb-Te compounds is provided, allowing a physics-based comprehension of the reset-to-set transition.     

Design of a Telescopic Linear Actuator Based on Hollow Shape Memory Springs

Shape memory alloys (SMAs) are smart materials exploited in many applications to build actuators with high power to mass ratio. Typical SMA drawbacks are: wires show poor stroke and excessive length, helical springs have limited mechanical bandwidth and high power consumption. This study is focused on the design of a large-scale linear SMA actuator conceived to maximize the stroke while limiting the overall size and the electric consumption. This result is achieved by adopting for the actuator a telescopic multi-stage architecture and using SMA helical springs with hollow cross section to power the stages. The hollow geometry leads to reduced axial size and mass of the actuator and to enhanced working frequency while the telescopic design confers to the actuator an indexable motion, with a number of different displacements being achieved through simple on-off control strategies. An analytical thermo-electro-mechanical model is developed to optimize the device. Output stroke and force are maximized while total size and power consumption are simultaneously minimized. Finally, the optimized actuator, showing good performance from all these points of view, is designed in detail.     

Mobilization and Leaching of Natural and Water Dispersible Colloids in Aggregated Volcanic Ash Soil Columns

Colloid-facilitated transport enhances migration of strongly sorbing compounds (e.g., radionuclides, phosphorus, heavy metals) in soil and groundwater. Mobilization, transport and deposition of soil colloids are the underlying processes governing colloid-facilitated contaminant transport. Although significant progress has been made in simulating mobilization and transport/deposition of model colloids in different collector systems, it may be inadequate for the prediction of natural colloidal behavior in the subsurface. This study quantifies the leaching of natural volcanic ash soil colloids (NC) as well as the simultaneous transport of applied water dispersible soil colloids (WDC) in aggregated volcanic ash soil columns. Two water-saturated soil columns were irrigated with artificial irrigation water (AIW) at an intensity of 80 mm/hr for 60 hours. Two additional columns were irrigated at the same intensity, but a colloidal suspension of 5 mg/L was applied after 20 hours for a period of 20 hours. Effluent colloid concentrations were measured in each experiment. HYDRUS-1D was used for the simulation and estimation of colloid transport parameters. The results clearly showed different kinetics for applied colloid transport and natural colloid leaching. Transport of applied WDC followed first-order attachment kinetics, while the two-site equilibrium/kinetic model with equal fractions of equilibrium and kinetic sites best described the leaching of NC. Coupling these best model approaches well predicted the simultaneous leaching of natural and applied colloids, hereby providing a useful tool for the design of colloid-based in-situ soil remediation systems.     

More than a master plan: Amman 2025

The recent plan for Amman, Jordan, combined elements of both master planning and strategic planning while pushing beyond the boundaries of both to incorporate governmental reorganization, national development concerns, and the “branding” of the city. The paper explores this deviation from traditional master planning and documents the innovations that emerged from a commitment to bring planning and implementation closer together in time and use the planning process to build planning capacity in Amman and throughout Jordan. As planners continue to negotiate between holistic visions and the pressures of development, Amman 2025 exposes the strengths and weaknesses of strategic planning and offers useful lessons.     

Personality–cognition relations across adulthood.

Although an increasing number of studies have investigated relations between dimensions of personality and level of cognitive functioning, the research results have been somewhat inconsistent. Furthermore, relatively little is known about whether the personality–cognition relations vary as a function of age in adulthood. The current project examined these issues with data from a sample of 2,317 adults between 18 and 96 years of age who each completed a personality inventory and performed a broad battery of cognitive tests. The results revealed strong relations of the personality trait of Openness with several distinct cognitive abilities and smaller relations of other personality traits with specific cognitive abilities. Comparisons across different age groups indicated that the personality–cognition relations were both qualitatively and quantitatively similar across the adult years. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Multiyear Performance of a Pervious Concrete Infiltration Basin BMP

The use of infiltration storm-water best management practices (BMPs) has become a more commonly used approach as a means of reducing postdevelopment runoff volumes in many areas throughout the United States. Although studies regarding the performance of infiltration BMPs are emerging, much remains to be learned about their design, construction, and operation. The increase in knowledge will improve the performance and longevity of these BMPs. The performance of one such infiltration basin over a 2-year cycle is presented in this paper. The study site is a pervious concrete infiltration basin BMP built in 2002 in a courtyard common area at Villanova University. The system consists of three linked infiltration beds lined with geotextile filter fabric, filled with coarse aggregate, and overlaid with pervious concrete. The natural soil beneath the infiltration BMP is a silty sand. The BMP is extensively instrumented to facilitate water quantity and quality research. Both water-quantity and -quality results are presented. The water-quantity analysis showed that the performance of the basin was directly related to its infiltration characteristics. The infiltration rate of the silty sand is cyclic, with higher rates during warmer periods and lower rates during colder periods. The water quality analysis investigated the pollutant reduction for chloride, copper, nitrogen, and phosphorus from the inlet to the surface-water outlet of the structure, as well as differences in pollutant concentration levels between the basin, surrounding ground, and varying soil layer elevations beneath the basin. In general, the pollutant reduction to the surface waters was greater than 90% from inlet to outlet, primarily influenced by the infiltration of the storm water into the natural soils below the BMP. The pollutant concentration of the infiltrating runoff was found to be higher than expected in the area adjacent to the bed when compared to concentration levels found at a similar depth beneath the infiltration bed. Comparison of pollutant concentration levels, as the water moved from within the storage bed to the soil beneath the bed, were shown to vary, with statistical differences found for mean concentration levels of both pH and copper levels; and no statistical differences were found for conductivity, total phosphorous, and chloride at each elevation.     

Review of Memory, war and trauma.

Reviews the book, Memory, war and trauma by Nigel C. Hunt (see record 2010-17048-000). Hunt’s book presents a very different perspective on how memory, war, and trauma interface, drawing upon a variety of sources not frequently accessed by psychologists. He promotes an interdisciplinary approach to studying memory and war; however, rather than drawing upon the usual fields, such as biology or sociology, Dr. Hunt suggests that a careful examination of history and literature are also integral to developing a complete understanding of memory and war. This book is not designed for individuals unfamiliar with the field of trauma and war. Memory, war and trauma highlights the limitations of current empirical approaches to studying war trauma and presents a narrative methodology that he argues will better capture the unique individual experience of trauma. Hunt rightly demonstrates weaknesses of current methods, and suggests that the narrative method may be the solution to some of the problems with current methods. Though his argument is likely that the narrative method should supplement rather than replace current experimental method, one is left feeling that he believes current methods are wholly inadequate and his method is better. Despite this central weakness, this book will be a benefit to psychologists who study and treat individuals touched by war because it will encourage them to think beyond traditional approaches to research and treatment. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Neurocognitive signs in prodromal Huntington disease.

Objective: PREDICT-HD is a large-scale international study of people with the Huntington disease (HD) CAG-repeat expansion who are not yet diagnosed with HD. The objective of this study was to determine the stage in the HD prodrome at which cognitive differences from CAG-normal controls can be reliably detected. Method: For each of 738 HD CAG-expanded participants, we computed estimated years to clinical diagnosis and probability of diagnosis in 5 years based on age and CAG-repeat expansion number (Langbehn, Brinkman, Falush, Paulsen, & Hayden, 2004). We then stratified the sample into groups: NEAR, estimated to be ≤9 years; MID, between 9 and 15 years; and FAR, ≥15 years. The control sample included 168 CAG-normal participants. Nineteen cognitive tasks were used to assess attention, working memory, psychomotor functions, episodic memory, language, recognition of facial emotion, sensory–perceptual functions, and executive functions. Results: Compared with the controls, the NEAR group showed significantly poorer performance on nearly all of the cognitive tests and the MID group on about half of the cognitive tests (p = .05, Cohen's d NEAR as large as ?1.17, MID as large as ?0.61). One test even revealed significantly poorer performance in the FAR group (Cohen's d = ?0.26). Individual tasks accounted for 0.2% to 9.7% of the variance in estimated proximity to diagnosis. Overall, the cognitive battery accounted for 34% of the variance; in comparison, the Unified Huntington's Disease Rating Scale motor score accounted for 11.7%. Conclusions: Neurocognitive tests are robust clinical indicators of the disease process prior to reaching criteria for motor diagnosis of HD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Adaptive Control System to Deliver Interactive Virtual Environment Content to Handheld Devices

Wireless communication advances have enabled emerging video streaming applications to mobile handheld devices. For example, it is possible to display and interact with complex 3D virtual environments on mobile devices that don’t have enough computational and storage capabilities (e.g. smart phones, PDAs) through remote rendering techniques, where a server renders 3D data and streams the corresponding image flow to the client. However, due to fluctuations in bandwidth characteristics and limited mobile device CPU capabilities, it is extremely challenging to design effective systems for streaming interactive multimedia over wireless networks. This paper presents a novel approach based on a controller that can automatically adjust streaming parameters basing on feedback measures from the client device. Experimental results prove the effectiveness of the proposed solution in coping with bandwidth changes, thus providing high Quality of Service (QoS) in remote visualizations.