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Showing papers by "University of Waterloo published in 2007"


Journal ArticleDOI
14 Sep 2007-Science
TL;DR: Synthesis of six case studies from around the world shows that couplings between human and natural systems vary across space, time, and organizational units and have legacy effects on present conditions and future possibilities.
Abstract: Integrated studies of coupled human and natural systems reveal new and complex patterns and processes not evident when studied by social or natural scientists separately. Synthesis of six case studies from around the world shows that couplings between human and natural systems vary across space, time, and organizational units. They also exhibit nonlinear dynamics with thresholds, reciprocal feedback loops, time lags, resilience, heterogeneity, and surprises. Furthermore, past couplings have legacy effects on present conditions and future possibilities.

2,890 citations


Journal ArticleDOI
TL;DR: Three cost-sensitive boosting algorithms are developed by introducing cost items into the learning framework of AdaBoost, which show that one of the proposed algorithms tallies with the stagewise additive modelling in statistics to minimize the cost exponential loss.

1,331 citations


Journal ArticleDOI
TL;DR: In this paper, high-resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year.
Abstract: High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year. X-ray images have revealed giant cavities and shock fronts in the hot gas that provide a direct and relatively reliable means of measuring the energy injected into hot atmospheres by active galactic nuclei (AGN). Average radio jet powers are near those required to offset radiative losses and to suppress cooling in isolated giant elliptical galaxies, and in larger systems up to the richest galaxy clusters. This coincidence suggests that heating and cooling are coupled by feedback, which suppresses star formation and the growth of luminous galaxies. How jet energy is converted to heat and the degree to which other heating mechanisms are contributing, e.g., thermal conduction, are not well understood. Outburst energies require substantial late growth of supermassive black holes. Unless all of the ∼10 62 erg required to suppress star formation is deposited in the cooling regions of clusters, AGN outbursts must alter large-scale properties of the intracluster medium.

1,283 citations


Book
27 Jul 2007
TL;DR: Radio Frequency Filter Networks for Wireless Communications-The System Perspective and Computer-Aided Synthesis of Characteristic Polynomials shows the impact of system design on the requirements of filter networks.
Abstract: Foreword Preface Acknowledgments 1 Radio Frequency (RF) Filter Networks for Wireless Communications-The System Perspective PART I: INTRODUCTION TO A COMMUNICATION SYSTEM, RADIO SPECTRUM, AND INFORMATION PART II: NOISE IN A COMMUNICATION CHANNEL PART III: IMPACT OF SYSTEM DESIGN ON THE REQUIRMENTS OF FILTER NETWORKS 2 Fundamentals of Circuit Theory Approximation 3 Characterization of Lossless Lowpass Prototype filter functions 4 Computer-Aided Synthesis of Characteristic Polynomials 5 Analysis of Multiport Microwave Networks 6 Synthesis of a General Class of the Chebyshev Filter Function 7 Synthesis of Network - Circuit Approach 8 Coupling Matrix Synthesis of Filter Networks 9 Reconfiguration of the Folded Coupling Matrix 10 Synthesis and Application of Extracted Pole and Trisection Elements 11 Microwave Resonators 12 Waveguide and Coaxial Lowpass Filters 13 Waveguide Realization of Single- and Dual-Mode Resonator Filters 14 Design and Physical Realization of Coupled Resonator Filters 15 Advanced EM-Based Design Techniques for Microwave Filters 16 Dielectric Resonator Filters 17 AllPass Phase and Group Delay Equalizer Networks 18 Multiplexer Theory and Design 19 Computer-Aided Diagnosis and Tuning of Microwave Filters 20 High-Power Considerations in Microwave Filter Networks Appendix A Appendix B Appendix C Appendix D Index

959 citations


Journal ArticleDOI
TL;DR: In this article, the physiological basis for plant growth-promotion effect is examined in some detail, and models are presented that endeavour to explain the seemingly paradoxical effects of ethylene on a plant's response to stress, how the expression of this enzyme is transcriptionally regulated in many bacterial strains and how ACC deaminase-containing plant growthpromoting bacteria alter plant gene expression and positively modulate plant growth.
Abstract: Plant growth-promoting bacteria that contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase facilitate plant growth and development by decreasing plant ethylene levels, especially following a variety of environmental stresses. In this review, the physiological basis for this growth-promotion effect is examined in some detail. In addition, models are presented that endeavour to explain (i) the seemingly paradoxical effects of ethylene on a plant’s response to stress, (ii) how the expression of this enzyme is transcriptionally regulated in many bacterial strains and (iii) how ACC deaminase-containing plant growth-promoting bacteria alter plant gene expression and positively modulate plant growth.

926 citations


Proceedings ArticleDOI
24 Jun 2007
TL;DR: In this paper, an overview of demand response in electricity market is presented, where the most common indices used for demand response evaluation are highlighted and some utilities experiences with different demand response programs are presented.
Abstract: This paper presents an overview of demand response (DR) in electricity market. The definition and a classification of demand response will be presented. Different potential benefits as well as cost components of demand response will be presented. The most common indices used for demand response evaluation are highlighted. Moreover, some utilities experiences with different demand response programs will be presented.

909 citations


Journal ArticleDOI
TL;DR: It is demonstrated that the proposed protocol cannot only guarantee the requirements of security and privacy but can also provide the desired traceability of each vehicle in the case where the ID of the message sender has to be revealed by the authority for any dispute event.
Abstract: In this paper, we first identify some unique design requirements in the aspects of security and privacy preservation for communications between different communication devices in vehicular ad hoc networks. We then propose a secure and privacy-preserving protocol based on group signature and identity (ID)-based signature techniques. We demonstrate that the proposed protocol cannot only guarantee the requirements of security and privacy but can also provide the desired traceability of each vehicle in the case where the ID of the message sender has to be revealed by the authority for any dispute event. Extensive simulation is conducted to verify the efficiency, effectiveness, and applicability of the proposed protocol in various application scenarios under different road systems.

871 citations


Journal ArticleDOI
TL;DR: In this paper, high-resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year.
Abstract: High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year. X-ray images have revealed giant cavities and shock fronts in the hot gas that provide a direct and relatively reliable means of measuring the energy injected into hot atmospheres by active galactic nuclei (AGN). Average radio jet powers are near those required to offset radiative losses and to suppress cooling in isolated giant elliptical galaxies, and in larger systems up to the richest galaxy clusters. This coincidence suggests that heating and cooling are coupled by feedback, which suppresses star formation and the growth of luminous galaxies. How jet energy is converted to heat and the degree to which other heating mechanisms are contributing, eg. thermal conduction, are not well understood. Outburst energies require substantial late growth of supermassive black holes. Unless all of the approximately 10E62 erg required to suppress star formation is deposited in the cooling regions of clusters, AGN outbursts must alter large-scale properties of the intracluster medium.

865 citations


Journal ArticleDOI
TL;DR: A sodium/lithium iron phosphate, A(2)FePO(4)F (A=Na, Li), that could serve as a cathode in either Li-ion or Na-ion cells and possesses facile two-dimensional pathways for Li+ transport, and the structural changes on reduction-oxidation are minimal.
Abstract: In the search for new positive-electrode materials for lithium-ion batteries, recent research has focused on nanostructured lithium transition-metal phosphates that exhibit desirable properties such as high energy storage capacity combined with electrochemical stability1,2. Only one member of this class—the olivine LiFePO4 (ref. 3)—has risen to prominence so far, owing to its other characteristics, which include low cost, low environmental impact and safety. These are critical for large-capacity systems such as plug-in hybrid electric vehicles. Nonetheless, olivine has some inherent shortcomings, including one-dimensional lithium-ion transport and a two-phase redox reaction that together limit the mobility of the phase boundary4,5,6,7. Thus, nanocrystallites are key to enable fast rate behaviour8,9. It has also been suggested that the long-term economic viability of large-scale Li-ion energy storage systems could be ultimately limited by global lithium reserves, although this remains speculative at present. (Current proven world reserves should be sufficient for the hybrid electric vehicle market, although plug-in hybrid electric vehicle and electric vehicle expansion would put considerable strain on resources and hence cost effectiveness.) Here, we report on a sodium/lithium iron phosphate, A2FePO4F (A=Na, Li), that could serve as a cathode in either Li-ion or Na-ion cells. Furthermore, it possesses facile two-dimensional pathways for Li+ transport, and the structural changes on reduction–oxidation are minimal. This results in a volume change of only 3.7% that—unlike the olivine—contributes to the absence of distinct two-phase behaviour during redox, and a reversible capacity that is 85% of theoretical.

837 citations


Journal ArticleDOI
TL;DR: A review of the published work on the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, with an emphasis on its biochemistry, protein structure, genes, and regulation.
Abstract: To date, there has been only limited commercial use of plant growth-promoting bacteria in agriculture, horticulture, and silviculture. However, with recent progress toward understanding the mechanisms that these organisms utilize to facilitate plant growth, the use of plant growth-promoting bacteria is expected to continue to increase worldwide. One of the key mechanisms employed by plant growth-promoting bacteria to facilitate plant growth is the lowering of plant ethylene levels by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. This article reviews the published work on this enzyme, with an emphasis on its biochemistry, protein structure, genes, and regulation. In addition, this article provides some initial insights into the changes in both plants and ACC deaminase-containing plant growth-promoting bacteria as a consequence of plant-microbe interactions. Finally, a brief discussion of how bacterial ACC deaminase and indoleacetic acid (IAA) together modulate plant growth and development i...

795 citations


Journal ArticleDOI
TL;DR: In this article, an analytical overview of the potential of pervaporation for separating liquid mixtures in terms of the solubility parameter and the kinetic parameter of solvents is provided.

Journal ArticleDOI
TL;DR: Untangling complexities, such as reciprocal effects and emergent properties, can lead to novel scientific discoveries and is essential to developing effective policies for ecological and socioeconomic sustainability.
Abstract: Humans have continuously interacted with natural systems, resulting in the formation and development of coupled human and natural systems (CHANS). Recent studies reveal the complexity of organizational, spatial, and temporal couplings of CHANS. These couplings have evolved from direct to more indirect interactions, from adjacent to more distant linkages, from local to global scales, and from simple to complex patterns and processes. Untangling complexities, such as reciprocal effects and emergent properties, can lead to novel scientific discoveries and is essential to developing effective policies for ecological and socioeconomic sustainability. Opportunities for truly integrating various disciplines are emerging to address fundamental questions about CHANS and meet society's unprecedented challenges.

Proceedings ArticleDOI
23 May 2007
TL;DR: Current requirements engineering (RE) research is reviewed and future research directions suggested by emerging software needs are identified, which aim to address RE needs for emerging systems of the future.
Abstract: In this paper, we review current requirements engineering (RE) research and identify future research directions suggested by emerging software needs. First, we overview the state of the art in RE research. The research is considered with respect to technologies developed to address specific requirements tasks, such as elicitation, modeling, and analysis. Such a review enables us to identify mature areas of research, as well as areas that warrant further investigation. Next, we review several strategies for performing and extending RE research results, to help delineate the scope of future research directions. Finally, we highlight what we consider to be the "hot" current and future research topics, which aim to address RE needs for emerging systems of the future.

Journal ArticleDOI
TL;DR: In this article, the authors reviewed and critically examined evidence related to parks and recreation as features of the built environment and the relationship of these settings to physical activity (PA) and reported an empirical relationship between parks or recreation variables and PA variables.
Abstract: Research on physical activity (PA) has expanded in recent years to examine environmental influences that enhance or limit the opportunities people have to be active. The purpose of this study was to review and critically examine evidence related to parks and recreation as features of the built environment and the relationship of these settings to PA. Fifty studies were retrieved from four major databases that reported an empirical relationship between parks or recreation variables and PA variables. Mixed associations with PA were observed for different types of parks or recreation settings, while proximity to parks or recreation was generally associated with increased PA. Shortcomings exist in this literature and many opportunities for researching parks, recreation, and active living are evident for the future.

Journal ArticleDOI
TL;DR: Beneficial applications of chemical surfactants and biosurfactants in various industries are discussed in this review.

Proceedings ArticleDOI
21 Mar 2007
TL;DR: An adaptive resource control system that dynamically adjusts the resource shares to individual tiers in order to meet application-level quality of service (QoS) goals while achieving high resource utilization in the data center is developed.
Abstract: Data centers are often under-utilized due to over-provisioning as well as time-varying resource demands of typical enterprise applications. One approach to increase resource utilization is to consolidate applications in a shared infrastructure using virtualization. Meeting application-level quality of service (QoS) goals becomes a challenge in a consolidated environment as application resource needs differ. Furthermore, for multi-tier applications, the amount of resources needed to achieve their QoS goals might be different at each tier and may also depend on availability of resources in other tiers. In this paper, we develop an adaptive resource control system that dynamically adjusts the resource shares to individual tiers in order to meet application-level QoS goals while achieving high resource utilization in the data center. Our control system is developed using classical control theory, and we used a black-box system modeling approach to overcome the absence of first principle models for complex enterprise applications and systems. To evaluate our controllers, we built a testbed simulating a virtual data center using Xen virtual machines. We experimented with two multi-tier applications in this virtual data center: a two-tier implementation of RUBiS, an online auction site, and a two-tier Java implementation of TPC-W. Our results indicate that the proposed control system is able to maintain high resource utilization and meets QoS goals in spite of varying resource demands from the applications.

Journal ArticleDOI
TL;DR: An efficient quantum algorithm for simulating the evolution of a quantum state for a sparse Hamiltonian H over a given time t is presented in terms of a procedure for computing the matrix entries of H.
Abstract: We present an efficient quantum algorithm for simulating the evolution of a quantum state for a sparse Hamiltonian H over a given time t in terms of a procedure for computing the matrix entries of H. In particular, when H acts on n qubits, has at most a constant number of nonzero entries in each row/column, and ||H|| is bounded by a constant, we may select any positive integer k such that the simulation requires O((log*n)t1+1/2k) accesses to matrix entries of H. We also show that the temporal scaling cannot be significantly improved beyond this, because sublinear time scaling is not possible.

Journal ArticleDOI
TL;DR: In this paper, the surface chemistry of the following cathode materials: LiCoO 2, V 2 O 5, LiMn 2 O 4, Li Mn 0.5 O 4 and Li MmN 0.

Journal ArticleDOI
TL;DR: DDS performance is compared to the shuffled complex evolution (SCE) algorithm for multiple optimization test functions as well as real and synthetic SWAT2000 model automatic calibration formulations and results show DDS to be more efficient and effective than SCE.
Abstract: [1] A new global optimization algorithm, dynamically dimensioned search (DDS), is introduced for automatic calibration of watershed simulation models. DDS is designed for calibration problems with many parameters, requires no algorithm parameter tuning, and automatically scales the search to find good solutions within the maximum number of user-specified function (or model) evaluations. As a result, DDS is ideally suited for computationally expensive optimization problems such as distributed watershed model calibration. DDS performance is compared to the shuffled complex evolution (SCE) algorithm for multiple optimization test functions as well as real and synthetic SWAT2000 model automatic calibration formulations. Algorithms are compared for optimization problems ranging from 6 to 30 dimensions, and each problem is solved in 1000 to 10,000 total function evaluations per optimization trial. Results are presented so that future modelers can assess algorithm performance at a computational scale relevant to their modeling case study. In all four of the computationally expensive real SWAT2000 calibration formulations considered here (14, 14, 26, and 30 calibration parameters), results show DDS to be more efficient and effective than SCE. In two cases, DDS requires only 15–20% of the number of model evaluations used by SCE in order to find equally good values of the objective function. Overall, the results also show that DDS rapidly converges to good calibration solutions and easily avoids poor local optima. The simplicity of the DDS algorithm allows for easy recoding and subsequent adoption into any watershed modeling application framework.

Journal ArticleDOI
TL;DR: This paper proposes a general model which, under mild assumptions, will generate provably random bits with some tolerance to adversarial manipulation and running in the megabit-per-second range, and develops fault-attack models and the properties of resilient functions to withstand such attacks.
Abstract: This paper is a contribution to the theory of true random number generators based on sampling phase jitter in oscillator rings. After discussing several misconceptions and apparently insurmountable obstacles, we propose a general model which, under mild assumptions, will generate provably random bits with some tolerance to adversarial manipulation and running in the megabit-per-second range. A key idea throughout the paper is the fill rate, which measures the fraction of the time domain in which the analog output signal is arguably random. Our study shows that an exponential increase in the number of oscillators is required to obtain a constant factor improvement in the fill rate. Yet, we overcome this problem by introducing a postprocessing step which consists of an application of an appropriate resilient function. These allow the designer to extract random samples only from a signal with only moderate fill rate and, therefore, many fewer oscillators than in other designs. Last, we develop fault-attack models and we employ the properties of resilient functions to withstand such attacks. All of our analysis is based on rigorous methods, enabling us to develop a framework in which we accurately quantify the performance and the degree of resilience of the design

Journal ArticleDOI
15 Oct 2007-Cancer
TL;DR: Data from randomized, controlled trials of zoledronic acid were retrospectively analyzed to assess the effect of pathologic fractures on survival in patients with malignant bone disease.
Abstract: BACKGROUND. Data from randomized, controlled trials of zoledronic acid were retrospectively analyzed to assess the effect of pathologic fractures on survival in patients with malignant bone disease. METHODS. A Cox regression model was used to estimate the effect of fractures (time-dependent variable) on survival in patients with stage III multiple myeloma or bone metastases from solid tumors enrolled in 3 large trials. Patients were randomized to receive zoledronic acid, pamidronate, or placebo every 3–4 weeks for up to 24 months (prostate cancer, breast cancer, and multiple myeloma) or up to 21 months (lung and other solid tumors). RESULTS. A total of 3049 patients with multiple myeloma (n = 513), breast (n = 1130), prostate (n = 640), or lung cancer or other solid tumors (n = 766) were included in this analysis. Patients with multiple myeloma had the highest fracture incidence (43%), followed by breast (35%), prostate (19%), and lung cancer (17%). In all tumor types except lung, pathologic fracture was associated with a significant increase in risk of death, and breast cancer patients had the greatest increased risk. After adjustment for baseline characteristics, including performance status and prior skeletal complications, breast cancer patients who developed a pathologic fracture on study had a significant 32% increased risk of death relative to patients without a fracture (hazard ratio = 1.32; P 20% increased risk of death. CONCLUSIONS. These results suggest that fractures are associated with increased risk of death in patients with malignant bone disease. Therefore, preventing fractures is an important goal of therapy. Cancer 2007. © 2007 American Cancer Society.

Journal ArticleDOI
01 Nov 2007
TL;DR: This paper considers an aggregated channel model which takes into account both path-loss and turbulence-induced log-normal fading in free-space optical systems operating in atmospheric turbulence channels and derived closed form expressions for outage probability of the relaying schemes under consideration.
Abstract: In this paper, we present relay-assisted transmission as a powerful fading mitigation tool for free-space optical systems operating in atmospheric turbulence channels. We study both serial (i.e., multi-hop transmission) and parallel (i.e., cooperative diversity) relaying encoupled with amplify-and-forward and decode-and-forward modes. We consider an aggregated channel model which takes into account both path-loss and turbulence-induced log-normal fading. Since fading variance is distance-dependent in free-space optical systems, relay-assisted transmission takes advantage of the resulting shorter hops and yields significant performance improvements. We derive outage probability of the relaying schemes under consideration which are further confirmed through Monte-Carlo simulations. Our outage probability analysis demonstrates that an impressive performance improvement of 18.5 dB is possible with the use of a single relay at a target outage probability of 10-6.

Journal ArticleDOI
TL;DR: Inelastic light scattering is an intensively used tool in the study of electronic properties of solids as discussed by the authors, which provides new insights into anisotropic and complex many-body behavior of electrons in various systems.
Abstract: Inelastic light scattering is an intensively used tool in the study of electronic properties of solids. Triggered by the discovery of high-temperature superconductivity in the cuprates and by new developments in instrumentation, light scattering in both the visible (Raman effect) and x-ray part of the electromagnetic spectrum has become a method complementary to optical (infrared) spectroscopy while providing additional and relevant information. The main purpose of the review is to position Raman scattering with regard to single-particle methods like angle-resolved photoemission spectroscopy, and other transport and thermodynamic measurements in correlated materials. Particular focus will be placed on photon polarizations and the role of symmetry to elucidate the dynamics of electrons in different regions of the Brillouin zone. This advantage over conventional transport (usually measuring averaged properties) provides new insights into anisotropic and complex many-body behavior of electrons in various systems. Recent developments in the theory of electronic Raman scattering in correlated systems and experimental results in paradigmatic materials such as the A15 superconductors, magnetic and paramagnetic insulators, compounds with competing orders, as well as the cuprates with high superconducting transition temperatures are reviewed. An overview of the manifestations of complexity in the Raman response due to the impact of correlations and developing competing orders is presented. In a variety of materials, observations which may be understood and a summary of important open questions that pave the way to a detailed understanding of correlated electron systems, are discussed.

Journal ArticleDOI
TL;DR: Temporal self-regulation theory as discussed by the authors is a theoretical framework for understanding human behavior in general, where the rationality of human behavior largely depends on the temporal frame adopted; behaviors judged to be maladaptive in the long-run are usually driven by a strongly favorable balance of immediate costs and benefits.
Abstract: Human behavior often seems “maladaptive”, “self-defeating”, or “dysfunctional” to the observer. Upon closer examination, the rationality of human behavior largely depends on the temporal frame adopted; behaviors judged to be maladaptive in the long-run are usually driven by a strongly favorable balance of immediate costs and benefits. That is, many ‘‘maladaptive’’ behaviors are associated with substantial long-term costs and few (if any) long-term benefits; however, these same behaviors are frequently associated with many benefits and few costs for the individual at the time of action. In contrast, many avoided behaviors that seem ‘‘adaptive’’ to the outside observer, are in fact associated with substantial costs (and few benefits) at the time of action, leading to the perplexing but common state of affairs where individuals know ‘‘what is good for them’’, but do not do it. We present a new theoretical framework—Temporal Self-Regulation Theory—as a way of understanding human behavior in general, ...

Proceedings ArticleDOI
15 Apr 2007
TL;DR: A framework that encapsulates a state space model and efficient query processing techniques to tackle the challenges of uncertain data settings is constructed and it is proved that the techniques are optimal in terms of the number of accessed tuples and materialized search states.
Abstract: Top-k processing in uncertain databases is semantically and computationally different from traditional top-k processing. The interplay between score and uncertainty makes traditional techniques inapplicable. We introduce new probabilistic formulations for top-k queries. Our formulations are based on "marriage" of traditional top-k semantics and possible worlds semantics. In the light of these formulations, we construct a framework that encapsulates a state space model and efficient query processing techniques to tackle the challenges of uncertain data settings. We prove that our techniques are optimal in terms of the number of accessed tuples and materialized search states. Our experiments show the efficiency of our techniques under different data distributions with orders of magnitude improvement over naive materialization of possible worlds.

Journal ArticleDOI
01 Jul 2007-Tellus B
TL;DR: In this paper, the diverse role of land-use/land-cover change on precipitation has been investigated and it has been shown that land conversion continues at a rapid pace, this type of human disturbance of the climate system will continue and become even more significant in the coming decades.
Abstract: This paper documents the diverse role of land-use/land-cover change on precipitation. Since land conversion continues at a rapid pace, this type of human disturbance of the climate system will continue and become even more significant in the coming decades.

Journal ArticleDOI
TL;DR: Sugarcane bagasse hydrolysis with 2.5% (v/v) HCl yielded 30.29g/L total reducing sugars along with various fermentation inhibitors such as furans, phenolics and acetic acid with maximum ethanol yield from ion exchange treated hydrolysate.

Journal ArticleDOI
TL;DR: In this paper, the SU(Nc) super Yang-Mills theory coupled with Nf << Nc flavors of fundamental matter at finite temperature and baryon density is studied.
Abstract: We use holographic techniques to study SU(Nc) super Yang-Mills theory coupled to Nf << Nc flavours of fundamental matter at finite temperature and baryon density. We focus on four dimensions, for which the dual description consists of Nf D7-branes in the background of Nc black D3-branes, but our results apply in other dimensions as well. A non-zero chemical potential μb or baryon number density nb is introduced via a nonvanishing worldvolume gauge field on the D7-branes. Ref. [1] identified a first order phase transition at zero density associated with `melting' of the mesons. This extends to a line of phase transitions for small nb, which terminates at a critical point at finite nb. Investigation of the D7-branes' thermodynamics reveals that (∂μb/∂nb)T<0 in a small region of the phase diagram, indicating an instability. We comment on a possible new phase which may appear in this region.

Journal ArticleDOI
TL;DR: This paper presents a preliminary review of Evidence Theory and explains how the multi-sensor engine diagnosis problem can be framed in the context of this theory, in terms of faults frame of discernment, mass functions and the rule for combining pieces of evidence.

Journal ArticleDOI
TL;DR: In this paper, the pull-in instability in microelectromechanical (MEMS) resonators was studied and the authors proposed a low-voltage MEMS RF switch actuated with a combined DC and AC loading, which uses a voltage much lower than the traditionally used DC voltage.
Abstract: We study the pull-in instability in microelectromechanical (MEMS) resonators and find that characteristics of the pull-in phenomenon in the presence of AC loads differ from those under purely DC loads. We analyze this phenomenon, dubbed dynamic pull-in, and formulate safety criteria for the design of MEMS resonant sensors and filters excited near one of their natural frequencies. We also utilize this phenomenon to design a low-voltage MEMS RF switch actuated with a combined DC and AC loading. The new switch uses a voltage much lower than the traditionally used DC voltage. Either the frequency or the amplitude of the AC loading can be adjusted to reduce the driving voltage and switching time. The new actuation method has the potential of solving the problem of high driving voltages of RF MEMS switches.