Showing papers by "University of Waterloo published in 2008"
TL;DR: In this article, the authors present a summary of demand response in deregulated electricity markets and highlight the most common indices used for DR measurement and evaluation, and some utilities' experiences with different demand response programs are discussed.
1,751 citations
TL;DR: Superconducting quantum bits (qubits) form the key component of these circuits and their quantum state is manipulated by using electromagnetic pulses to control the magnetic flux, the electric charge or the phase difference across a Josephson junction.
Abstract: Superconducting circuits are macroscopic in size but have generic quantum properties such as quantized energy levels, superposition of states, and entanglement, all of which are more commonly associated with atoms. Superconducting quantum bits (qubits) form the key component of these circuits. Their quantum state is manipulated by using electromagnetic pulses to control the magnetic flux, the electric charge or the phase difference across a Josephson junction (a device with nonlinear inductance and no energy dissipation). As such, superconducting qubits are not only of considerable fundamental interest but also might ultimately form the primitive building blocks of quantum computers.
1,561 citations
TL;DR: Findings further corroborate that TDP-43 is involved in ALS pathogenesis and reports eight missense mutations in nine individuals—six from individuals with sporadic ALS and three from those with familial ALS (FALS)—and a concurring increase of a smaller T DP-43 product.
Abstract: Recently, TDP-43 was identified as a key component of ubiquitinated aggregates in amyotrophic lateral sclerosis (ALS), an adult-onset neurological disorder that leads to the degeneration of motor neurons. Here we report eight missense mutations in nine individuals--six from individuals with sporadic ALS (SALS) and three from those with familial ALS (FALS)--and a concurring increase of a smaller TDP-43 product. These findings further corroborate that TDP-43 is involved in ALS pathogenesis.
1,453 citations
TL;DR: This paper presents a novel algorithm to accelerate the differential evolution (DE), which employs opposition-based learning (OBL) for population initialization and also for generation jumping and results confirm that the ODE outperforms the original DE and FADE in terms of convergence speed and solution accuracy.
Abstract: Evolutionary algorithms (EAs) are well-known optimization approaches to deal with nonlinear and complex problems. However, these population-based algorithms are computationally expensive due to the slow nature of the evolutionary process. This paper presents a novel algorithm to accelerate the differential evolution (DE). The proposed opposition-based DE (ODE) employs opposition-based learning (OBL) for population initialization and also for generation jumping. In this work, opposite numbers have been utilized to improve the convergence rate of DE. A comprehensive set of 58 complex benchmark functions including a wide range of dimensions is employed for experimental verification. The influence of dimensionality, population size, jumping rate, and various mutation strategies are also investigated. Additionally, the contribution of opposite numbers is empirically verified. We also provide a comparison of ODE to fuzzy adaptive DE (FADE). Experimental results confirm that the ODE outperforms the original DE and FADE in terms of convergence speed and solution accuracy.
1,419 citations
TL;DR: It is shown that by using mixed design schemes, rather than decomposition schemes, and taking the statistical properties of the interference terms into account, the power offset of the system can be improved.
Abstract: In a multiple-antenna system with two transmitters and two receivers, a scenario of data communication, known as the X channel, is studied in which each receiver receives data from both transmitters. In this scenario, it is assumed that each transmitter is unaware of the other transmitter's data (noncooperative scenario). This system can be considered as a combination of two broadcast channels (from the transmitters' points of view) and two multiple-access channels (from the receivers' points of view). Taking advantage of both perspectives, two signaling schemes for such a scenario are developed. In these schemes, some linear filters are employed at the transmitters and at the receivers which decompose the system into either two noninterfering multiple-antenna broadcast subchannels or two noninterfering multiple-antenna multiple-access subchannels. The main objective in the design of the filters is to exploit the structure of the channel matrices to achieve the highest multiplexing gain (MG). It is shown that the proposed noncooperative signaling schemes outperform other known noncooperative schemes in terms of the achievable MG. In particular, it is shown that in some specific cases, the achieved MG is the same as the MG of the system if full cooperation is provided either between the transmitters or between the receivers. In the second part of the paper, it is shown that by using mixed design schemes, rather than decomposition schemes, and taking the statistical properties of the interference terms into account, the power offset of the system can be improved. The power offset represents the horizontal shift in the curve of the sum-rate versus the total power in decibels.
1,176 citations
TL;DR: In this paper, an adaptive decentralized droop controller of paralleled inverter-based distributed generation (DG) units is presented to preserve the power sharing stability, which is based on the static droop characteristics combined with an adaptive transient droop function.
Abstract: This paper addresses the low-frequency relative stability problem in paralleled inverter-based distributed generation (DG) units in microgrids. In the sense of the small-signal dynamics of a microgrid, it can be shown that as the demanded power of each inverter changes, the low-frequency modes of the power sharing dynamics drift to new locations and the relative stability is remarkably affected, and eventually, instability can be yielded. To preserve the power sharing stability, an adaptive decentralized droop controller of paralleled inverter-based DG units is presented in this paper. The proposed power sharing strategy is based on the static droop characteristics combined with an adaptive transient droop function. Unlike conventional droop controllers, which yield 1-DOF tunable controller, the proposed droop controller yields 2-DOF tunable controller. Subsequently, the dynamic performance of the power sharing mechanism can be adjusted, without affecting the static droop gain, to damp the oscillatory modes of the power sharing controller. To account for the power modes immigration at different loading conditions, the transient droop gains are adaptively scheduled via small-signal analysis of the power sharing mechanism along the loading trajectory of each DG unit to yield the desired transient and steady-state response. The gain adaptation scheme utilizes the filtered active and reactive powers as indices; therefore, a stable and smooth power injection performance can be obtained at different loading conditions. The adaptive nature of the proposed controller ensures active damping of power oscillations at different operating conditions, and yields a stable and robust performance of the paralleled inverter system.
1,130 citations
20 Jul 2008
TL;DR: This paper develops a framework for evaluation that systematically rewards novelty and diversity into a specific evaluation measure, based on cumulative gain, and demonstrates the feasibility of this approach using a test collection based on the TREC question answering track.
Abstract: Evaluation measures act as objective functions to be optimized by information retrieval systems. Such objective functions must accurately reflect user requirements, particularly when tuning IR systems and learning ranking functions. Ambiguity in queries and redundancy in retrieved documents are poorly reflected by current evaluation measures. In this paper, we present a framework for evaluation that systematically rewards novelty and diversity. We develop this framework into a specific evaluation measure, based on cumulative gain. We demonstrate the feasibility of our approach using a test collection based on the TREC question answering track.
988 citations
TL;DR: This survey describes and classify top-k processing techniques in relational databases including query models, data access methods, implementation levels, data and query certainty, and supported scoring functions, and shows the implications of each dimension on the design of the underlying techniques.
Abstract: Efficient processing of top-k queries is a crucial requirement in many interactive environments that involve massive amounts of data. In particular, efficient top-k processing in domains such as the Web, multimedia search, and distributed systems has shown a great impact on performance. In this survey, we describe and classify top-k processing techniques in relational databases. We discuss different design dimensions in the current techniques including query models, data access methods, implementation levels, data and query certainty, and supported scoring functions. We show the implications of each dimension on the design of the underlying techniques. We also discuss top-k queries in XML domain, and show their connections to relational approaches.
893 citations
TL;DR: This article critically reviews some ethanol fermentation technologies from sugar and starch feedstocks, particularly those key aspects that have been neglected or misunderstood, and recommends self-immobilization of yeast cells through their flocculation to effectively overcome these drawbacks.
868 citations
TL;DR: In this paper, the authors assumed that the Chinese Altay-East Junggar-Eastern Tien Shan domain was more closely located to Siberia, while the West Junggars and Yili domains occupied an intermediate position near the Kazakhstan block in the early Paleozoic Paleoasian Ocean.
826 citations
TL;DR: The objective of this systematic review was to update the 1997 meta‐analysis of randomized controlled trials to reassess the efficacy of doxorubicin‐based chemotherapy with respect to recurrence and survival.
Abstract: Background The use of adjuvant chemotherapy to treat adults with localized resectable soft-tissue sarcoma remains controversial. The objective of this systematic review was to update the 1997 meta-analysis of randomized controlled trials (RCTs) to reassess the efficacy of doxorubicin-based chemotherapy with respect to recurrence and survival. Methods A comprehensive literature search was performed to identify RCTs of adjuvant chemotherapy for adult patients diagnosed with localized resectable soft-tissue sarcoma. Two reviewers independently assessed eligibility and quality of the studies using a modified version of the Detsky Quality Scale. The outcome measures were local, distant, and overall recurrence and survival calculated through the fixed effect or random effect model. Results Four new eligible trials were identified allowing for a total of 18 trials representing 1953 patients to be included in the analysis. The odds ratios (OR) for local recurrence was 0.73 (95% confidence interval [CI] 0.56-0.94; P = .02) in favor of chemotherapy. For distant and overall recurrence the OR was 0.67 (95% CI 0.56-0.82; P = .0001) in favor of chemotherapy. In terms of survival, doxorubicin alone had an OR of 0.84 (95% CI, 0.68-1.03; P = .09), which as not statistically significant. However, the OR for doxorubicin combined with ifosfamide was 0.56 (95% CI, 0.36-0.85; P = .01) in favor of chemotherapy. Conclusions This updated meta-analysis confirms the marginal efficacy of chemotherapy in localized resectable soft-tissue sarcoma with respect to local recurrence, distant recurrence, overall recurrence, and overall survival. These benefits are further improved with the addition of ifosfamide to doxorubicin-based regimens, but must be weighed against associated toxicities.
TL;DR: A hardware-constrained cognitive MAC, HC-MAC, is proposed to conduct efficient spectrum sensing and spectrum access decision in ad hoc cognitive radio networks while taking the hardware constraints into consideration.
Abstract: Radio spectrum resource is of fundamental importance for wireless communication. Recent reports show that most available spectrum has been allocated. While some of the spectrum bands (e.g., unlicensed band, GSM band) have seen increasingly crowded usage, most of the other spectrum resources are underutilized. This drives the emergence of open spectrum and dynamic spectrum access concepts, which allow unlicensed users equipped with cognitive radios to opportunistically access the spectrum not used by primary users. Cognitive radio has many advanced features, such as agilely sensing the existence of primary users and utilizing multiple spectrum bands simultaneously. However, in practice such capabilities are constrained by hardware cost. In this paper, we discuss how to conduct efficient spectrum management in ad hoc cognitive radio networks while taking the hardware constraints (e.g., single radio, partial spectrum sensing and spectrum aggregation limit) into consideration. A hardware-constrained cognitive MAC, HC-MAC, is proposed to conduct efficient spectrum sensing and spectrum access decision. We identify the issue of optimal spectrum sensing decision for a single secondary transmission pair, and formulate it as an optimal stopping problem. A decentralized MAC protocol is then proposed for the ad hoc cognitive radio networks. Simulation results are presented to demonstrate the effectiveness of our proposed protocol.
TL;DR: In this article, the authors achieved the state-of-the-art quantum channel capacity of 1.63 bits per photon using a method that overcomes fundamental limitations of earlier approaches to super-dense coding.
Abstract: Classically, one photon can transport one bit of information. But more is possible when quantum entanglement comes into play, and a record ‘channel capacity’ of 1.63 bits per photon has now been demonstrated, using a method that overcomes fundamental limitations of earlier approaches to ‘superdense coding’. Dense coding is arguably the protocol that launched the field of quantum communication1. Today, however, more than a decade after its initial experimental realization2, the channel capacity remains fundamentally limited as conceived for photons using linear elements. Bob can only send to Alice three of four potential messages owing to the impossibility of carrying out the deterministic discrimination of all four Bell states with linear optics3,4, reducing the attainable channel capacity from 2 to log23≈1.585 bits. However, entanglement in an extra degree of freedom enables the complete and deterministic discrimination of all Bell states5,6,7. Using pairs of photons simultaneously entangled in spin and orbital angular momentum8,9, we demonstrate the quantum advantage of the ancillary entanglement. In particular, we describe a dense-coding experiment with the largest reported channel capacity and, to our knowledge, the first to break the conventional linear-optics threshold. Our encoding is suited for quantum communication without alignment10 and satellite communication.
TL;DR: This review traces the origins of NSAIDs, their mechanism of action at the molecular level such as cyclooxygenase (COX) inhibition, development of selective COX-2 inhibitors, their adverse cardiovascular effects, and some recent developments targeted to the design of effective anti-inflammatory agents with reduced side effects.
Abstract: Purpose. NSAIDs constitute an important class of drugs with therapeutic applications that have spanned several centuries. Treatment of inflammatory conditions such as rheumatoid arthritis (RA) and osteoarthritis (OA) starting from the classic drug aspirin to the recent rise and fall of selective COX-2 inhibitors has provided an enthralling evolution. Efforts to discover an ultimate magic bullet to treat inflammation continues to be an important drug design challenge. This review traces the origins of NSAIDs, their mechanism of action at the molecular level such as cyclooxygenase (COX) inhibition, development of selective COX-2 inhibitors, their adverse cardiovascular effects, and some recent developments targeted to the design of effective anti-inflammatory agents with reduced side effects. Methods. Literature data is presented describing important discoveries pertaining to the sequential development of classical NSAIDs and then selective COX-2 inhibitors, their mechanism of action, the structural basis for COX inhibition, and recent discoveries. Results. A brief history of the development of NSAIDs and the market withdrawal of selective COX-2 inhibitors is explained, followed by the description of prostaglandin biosynthesis, COX isoforms, structure and function. The structural basis for COX-1 and COX-2 inhibition is described along with methods used to evaluate COX-1/COX-2 inhibition. This is followed by a section that encompasses the major chemical classes of selective COX-2 inhibitors. The final section describes briefly some of the recent advances toward developing effective anti-inflammatory agents such as nitric oxide donor NO-NSAIDs, dual COX/LOX inhibitors and anti-TNF therapy. Conclusions. A great deal of progress has been made toward developing novel anti-inflammatory agents. In spite of the tremendous advances in the last decade, the design and development of a safe, effective and economical therapy for treating inflammatory conditions still presents a major challenge.
TL;DR: Overall, the present study suggests that the Workplace Ostracism Scale is a reliable and valid measure and that the workplace ostracism construct has important implications for both individuals and organizations.
Abstract: This article outlines the development of a 10-item measure of workplace ostracism. Using 6 samples (including multisource and multiwave data), the authors developed a reliable scale with a unidimensional factor structure that replicated across 4 separate samples. The scale possessed both convergent and discriminant validity, and criterion-related validity was demonstrated through the scale's relation with basic needs, well-being, job attitudes, job performance, and withdrawal. Overall, the present study suggests that the Workplace Ostracism Scale is a reliable and valid measure and that the workplace ostracism construct has important implications for both individuals and organizations.
TL;DR: The authors propose that the high levels of support often observed for governmental and religious systems can be explained, in part, as a means of coping with the threat posed by chronically or situationally fluctuating levels of perceived personal control.
Abstract: The authors propose that the high levels of support often observed for governmental and religious systems can be explained, in part, as a means of coping with the threat posed by chronically or situationally fluctuating levels of perceived personal control. Three experiments demonstrated a causal relation between lowered perceptions of personal control and the defense of external systems, including increased beliefs in the existence of a controlling God (Studies 1 and 2) and defense of the overarching socio-political system (Study 4). A 4th experiment (Study 5) showed the converse to be true: A challenge to the usefulness of external systems of control led to increased illusory perceptions of personal control. In addition, a cross-national data set demonstrated that lower levels of personal control are associated with higher support for governmental control (across 67 nations; Study 3). Each study identified theoretically consistent moderators and mediators of these effects. The implications of these results for understanding why a high percentage of the population believes in the existence of God, and why people so often endorse and justify their socio-political systems, are discussed.
13 Apr 2008
TL;DR: An efficient batch signature verification scheme for communications between vehicles and RSUs (or termed vehicle- to-Infrastructure (V2I) communications), in which an RSU can verify multiple received signatures at the same time such that the total verification time can be dramatically reduced.
Abstract: With the adoption of state-of-the-art telecommunication technologies for sensing and collecting traffic related information, Vehicular Sensor Networks (VSNs) have emerged as a new application scenario that is envisioned to revolutionize the human driving experiences and traffic flow control systems. To avoid any possible malicious attack and resource abuse, employing a digital signature scheme is widely recognized as the most effective approach for VSNs to achieve authentication, integrity, and validity. However, when the number of signatures received by a Roadside Unit (RSU) becomes large, a scalability problem emerges immediately, where the RSU could be difficult to sequentially verify each received signature within 300 ms interval according to the current Dedicated Short Range Communications (DSRC) broadcast protocol. In this paper, we introduce an efficient batch signature verification scheme for communications between vehicles and RSUs (or termed vehicle- to-Infrastructure (V2I) communications), in which an RSU can verify multiple received signatures at the same time such that the total verification time can be dramatically reduced. We demonstrate that the proposed scheme can achieve conditional privacy preservation that is essential in VSNs, where each message launched by a vehicle is mapped to a distinct pseudo identity, while a trust authority can always retrieve the real identity of a vehicle from any pseudo identity. With the proposed scheme, since identity-based cryptography is employed in generating private keys for pseudo identities, certificates are not needed and thus transmission overhead can be significantly reduced.
TL;DR: By partially embedding and then removing gold nanospheres, a high surface coverage of well-defined nanodeformations on a polystyrene surface is produced, providing strong direct evidence for enhanced surface mobility relative to the bulk.
Abstract: The motion of polymer chain segments cooled below the glass transition temperature slows markedly; with sufficient cooling, segmental motion becomes completely arrested. There is debate as to whether the chain segments near the free surface, or in thin films, are affected in the same way as the bulk material. By partially embedding and then removing gold nanospheres, we produced a high surface coverage of well-defined nanodeformations on a polystyrene surface; to probe the surface dynamics, we measured the time-dependent relaxation of these surface deformations as a function of temperature from 277 to 369 kelvin. Surface relaxation was observed at all temperatures, providing strong direct evidence for enhanced surface mobility relative to the bulk. The deviation from bulk α relaxation became more pronounced as the temperature was decreased below the bulk glass transition temperature. The temperature dependence of the relaxation time was much weaker than that of the bulk α relaxation of polystyrene, and the process exhibited no discernible temperature dependence between 277 and 307 kelvin.
TL;DR: Several polymeric systems, such as homopolymers, block copolymers, microgels, hydrogels and polymer brushes at interfaces are reviewed, where important characteristics that govern their behavior in solutions are described.
Abstract: pH-Responsive polymers are systems whose solubility, volume, and chain conformation can be manipulated by changes in pH, co-solvent, and electrolytes. This review summarizes recent developments covering synthesis, physicochemical properties, and applications in various disciplines. A variety of synthetic methodologies comprising of emulsion polymerization and living radical polymerization techniques are described, and some of their salient features are highlighted. Several polymeric systems, such as homopolymers, block copolymers, microgels, hydrogels and polymer brushes at interfaces are reviewed, where important characteristics that govern their behavior in solutions are described. Potential applications of these systems in controlled drug delivery, personal and home care, industrial coatings, biological and membrane science, viscosity modifiers, colloid stabilization, and water remediation, are discussed.
TL;DR: The results of the current study illustrate that temporal asymmetry can be found in many independently ambulating stroke patients and highlights the need for a standard assessment of poststroke gait symmetry in light of the complex relationship with motor impairment and velocity.
TL;DR: The results indicate that interRAI items retain reliability when used across care settings, paving the way for cross domain application of the instruments as part of an integrated health information system.
Abstract: A multi-domain suite of instruments has been developed by the interRAI research collaborative to support assessment and care planning in mental health, aged care and disability services. Each assessment instrument comprises items common to other instruments and specialized items exclusive to that instrument. This study examined the reliability of the items from five instruments supporting home care, long term care, mental health, palliative care and post-acute care. Paired assessments on 783 individuals across 12 nations were completed within 72 hours of each other by trained assessors who were blinded to the others' assessment. Reliability was tested using weighted kappa coefficients. The overall kappa mean value for 161 items which are common to 2 or more instruments was 0.75. The kappa mean value for specialized items varied among instruments from 0.63 to 0.73. Over 60% of items scored greater than 0.70. The vast majority of items exceeded standard cut-offs for acceptable reliability, with only modest variation among instruments. The overall performance of these instruments showed that the interRAI suite has substantial reliability according to conventional cut-offs for interpreting the kappa statistic. The results indicate that interRAI items retain reliability when used across care settings, paving the way for cross domain application of the instruments as part of an integrated health information system.
TL;DR: In this paper, the transmon qubit was shown to be an improved superconducting charge qubit derived from the Cooper pair box, which results in homogeneously broadened transitions with relaxation and dephasing times in the microsecond range.
Abstract: We present an experimental realization of the transmon qubit, which is an improved superconducting charge qubit derived from the Cooper pair box. We experimentally verify the predicted exponential suppression of sensitivity to $1∕f$ charge noise. This removes the leading source of dephasing in charge qubits which results in homogeneously broadened transitions with relaxation and dephasing times in the microsecond range. Our systematic characterization of the qubit spectrum, anharmonicity, and charge dispersion shows excellent agreement with theory.
TL;DR: This paper present an alternative promising approach to ISI mitigation by the use of single-carrier (SC) modulation combined with frequency-domain equalization (FDE).
Abstract: This paper present an alternative promising approach to ISI mitigation by the use of single-carrier (SC) modulation combined with frequency-domain equalization (FDE).
TL;DR: It is found that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model.
Abstract: We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the spontaneous qubit decay into a microwave transmission-line cavity can accurately predict the qubit lifetimes over 2 orders of magnitude in time and more than an octave in frequency. Coherence times T1 and T_{2};{*} of more than a microsecond are reproducibly demonstrated.
TL;DR: This correspondence derives performance bounds for this problem for each of three decode-and-forward protocols for coded bidirectional cooperation and finds that in some cases, the achievable rate region of the four phase protocol contains points that are outside the outer bounds of the other two protocols.
Abstract: In coded bidirectional cooperation, two nodes wish to exchange messages over a shared half-duplex channel with the help of a relay. In this correspondence, we derive performance bounds for this problem for each of three decode-and-forward protocols. The first protocol is a two phase protocol where both users simultaneously transmit during the first phase and the relay alone transmits during the second. In this protocol, our bounds are tight. The second protocol considers sequential transmissions from the two users followed by a transmission from the relay while the third protocol is a hybrid of the first two protocols and has four phases. In the latter two protocols the bounds are not identical. Numerical evaluation shows that in some cases of interest our bounds do not differ significantly. Finally, in the Gaussian case with path loss, we derive achievable rates and compare the relative merits of each protocol. This case is of interest in cellular systems. Surprisingly, we find that in some cases, the achievable rate region of the four phase protocol contains points that are outside the outer bounds of the other two protocols.
TL;DR: This review has tried to cover the latest developments on enzyme systems of WRF, their low molecular mass mediators and their potential use for bioremediation of industrial pollutants.
Abstract: Increasing discharge and improper management of liquid and solid industrial wastes have created a great concern among industrialists and the scientific community over their economic treatment and safe disposal. White rot fungi (WRF) are versatile and robust organisms having enormous potential for oxidative bioremediation of a variety of toxic chemical pollutants due to high tolerance to toxic substances in the environment. WRF are capable of mineralizing a wide variety of toxic xenobiotics due to non-specific nature of their extracellular lignin mineralizing enzymes (LMEs). In recent years, a lot of work has been done on the development and optimization of bioremediation processes using WRF, with emphasis on the study of their enzyme systems involved in biodegradation of industrial pollutants. Many new strains have been identified and their LMEs isolated, purified and characterized. In this review, we have tried to cover the latest developments on enzyme systems of WRF, their low molecular mass mediators and their potential use for bioremediation of industrial pollutants.
TL;DR: This article examined whether brand exposure elicits automatic behavioral effects as does exposure to social primes and found that exposure to goal-relevant brands (i.e., those that represent a positively valenced characteristic) elicits behavior that is goal directed in nature.
Abstract: This article first examines whether brand exposure elicits automatic behavioral effects as does exposure to social primes. Results support the translation of these effects: participants primed with Apple logos behave more creatively than IBM primed and controls; Disney-primed participants behave more honestly than E!primed participants and controls. Second, this article investigates the hypothesis that exposure to goal-relevant brands (i.e., those that represent a positively valenced characteristic) elicits behavior that is goal directed in nature. Three experiments demonstrate that theprimedbehaviorshowedtypicalgoal-directedqualities, including increased performance postdelay, decreased performancepostprogress, and moderation by motivation.
TL;DR: This paper examined whether analysts resident in a country make more precise earnings forecasts for firms in that country than non-resident analysts and found an economically and statistically significant local analyst advantage even after controlling for firm and analyst characteristics.
TL;DR: In this article, the authors present an exploration of weak lensing by large-scale structure in the linear regime, using the third-year (T0003) CFHTLS Wide data release.
Abstract: Aims. We present an exploration of weak lensing by large-scale structure in the linear regime, using the third-year (T0003) CFHTLS Wide data release. Our results place tight constraints on the scaling of the amplitude of the matter power spectrum σ8 with the matter density Ωm. Methods. Spanning 57 square degrees to i � = 24.5 over three independent fields, the unprecedented contiguous area of this survey permits high signal-to-noise measurements of two-point shear statistics from 1 arcmin to 4 degrees. Understanding systematic errors in our analysis is vital in interpreting the results. We therefore demonstrate the percent-level accuracy of our method using STEP simulations, an E/B-mode decomposition of the data, and the star-galaxy cross correlation function. We also present a thorough analysis of the galaxy redshift distribution using redshift data from the CFHTLS T0003 Deep fields that probe the same spatial regions as the Wide fields. Results. We find σ8(Ωm/0.25) 0.64 = 0.785 ± 0.043 using the aperture-mass statistic for the full range of angular scales for an assumed flat cosmology, in excellent agreement with WMAP3 constraints. The largest physical scale probed by our analysis is 85 Mpc, assuming a mean redshift of lenses of 0.5 and a ΛCDM cosmology. This allows for the first time to constrain cosmology using only cosmic shear measurements in the linear regime. Using only angular scales θ> 85 arcmin, we find σ8(Ωm/0.25) 0.53 lin = 0.837 ± 0.084, which agree with the results from our full analysis. Combining our results with data from WMAP3, we find Ωm = 0.248 ± 0.019 and σ8 = 0.771 ± 0.029.
California Institute of Technology1, New Mexico Institute of Mining and Technology2, University of York3, University of Waterloo4, Leibniz Association5, Langley Research Center6, Goddard Space Flight Center7, Hampton University8, European Centre for Medium-Range Weather Forecasts9, University of Toronto10
TL;DR: In this article, the authors describe the retrievals algorithm used to determine temperature and height from radiance measurements by the Microwave Limb Sounder on EOS Aura, which is a "limbscanning" instrument, meaning that it views the atmosphere along paths that do not intersect the surface.
Abstract: This paper describes the retrievals algorithm used to determine temperature and height from radiance measurements by the Microwave Limb Sounder on EOS Aura. MLS is a "limbscanning" instrument, meaning that it views the atmosphere along paths that do not intersect the surface - it actually looks forwards from the Aura satellite. This means that the temperature retrievals are for a "profile" of the atmosphere somewhat ahead of the satellite. Because of the need to view a finite sample of the atmosphere, the sample spans a box about 1.5km deep and several tens of kilometers in width; the optical characteristics of the atmosphere mean that the sample is representative of a tube about 200-300km long in the direction of view. The retrievals use temperature analyses from NASA's Goddard Earth Observing System, Version 5 (GEOS-5) data assimilation system as a priori states. The temperature retrievals are somewhat deperrde~zt on these a priori states, especially in the lower stratosphere. An important part of the validation of any new dataset involves comparison with other, independent datasets. A large part of this study is concerned with such comparisons, using a number of independent space-based measurements obtained using different techniques, and with meteorological analyses. The MLS temperature data are shown to have biases that vary with height, but also depend on the validation dataset. MLS data are apparently biased slightly cold relative to correlative data in the upper troposphere and slightly warm in the middle stratosphere. A warm MLS bias in the upper stratosphere may be due to a cold bias in GEOS-5 temperatures.