Showing papers by "Ryerson University published in 2011"

The impact of corporate social responsibility on the cost of bank loans

Abstract: This study examines the link between corporate social responsibility (CSR) and bank debt. Our focus on banks exploits their specialized role as delegated monitors of the firm. Using a sample of 3996 loans to US firms, we find that firms with social responsibility concerns pay between 7 and 18 basis points more than firms that are more responsible. Lenders are more sensitive to CSR concerns in the absence of security. We document a mixed reaction to discretionary CSR investments. Low-quality borrowers that engage in discretionary CSR spending face higher loan spreads and shorter maturities, but lenders are indifferent to CSR investments by high-quality borrowers.

Entrepreneurial Motivations: What Do We Still Need to Know?

Abstract: This paper attempts to renew interest in a line of research that largely has been ignored for two decades but which is critical to the study of entrepreneurial cognitions, intentions, and their con...

Posttraumatic stress disorder and intimate relationship problems: A meta-analysis.

Abstract: Objective: The authors conducted a meta-analysis of empirical studies investigating associations between indices of posttraumatic stress disorder (PTSD) and intimate relationship problems to empirically synthesize this literature. Method: A literature search using PsycINFO, Medline, Published International Literature on Traumatic Stress (PILOTS), and Dissertation Abstracts was performed. The authors identified 31 studies meeting inclusion criteria. Results: True score correlations (ρ) revealed medium-sized associations between PTSD and intimate relationship discord (ρ = .38, N = 7,973, K = 21), intimate relationship physical aggression perpetration (ρ = .42, N = 4,630, K = 19), and intimate relationship psychological aggression perpetration (ρ = .36, N = 1,501, K = 10). The strength of the association between PTSD and relationship discord was higher in military (vs. civilian) samples, and when the study was conducted in the United States (vs. other country), and the study represented a doctoral dissertation (vs. published article). The strength of the association between PTSD and physical aggression was higher in military (vs. civilian) samples, males (vs. females), community (vs. clinical) samples, studies examining PTSD symptom severity (vs. diagnosis), when the physical aggression measure focused exclusively on severe violence (vs. a more inclusive measure), and the study was published (vs. dissertation). For the PTSD-psychological aggression association, 98% of the variance was accounted for by methodological artifacts such as sampling and measurement error; consequently, no moderators were examined in this relationship. Conclusions: Findings highlight a need for the examination of models explaining the relationship difficulties associated with PTSD symptomatology and interventions designed to treat problems in both areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved). Language: en

Finite-Time Attitude Tracking Control for Spacecraft Using Terminal Sliding Mode and Chebyshev Neural Network

Abstract: A finite-time attitude tracking control scheme is proposed for spacecraft using terminal sliding mode and Chebyshev neural network (NN) (CNN). The four-parameter representations (quaternion) are used to describe the spacecraft attitude for global representation without singularities. The attitude state (i.e., attitude and velocity) error dynamics is transformed to a double integrator dynamics with a constraint on the spacecraft attitude. With consideration of this constraint, a novel terminal sliding manifold is proposed for the spacecraft. In order to guarantee that the output of the NN used in the controller is bounded by the corresponding bound of the approximated unknown function, a switch function is applied to generate a switching between the adaptive NN control and the robust controller. Meanwhile, a CNN, whose basis functions are implemented using only desired signals, is introduced to approximate the desired nonlinear function and bounded external disturbances online, and the robust term based on the hyperbolic tangent function is applied to counteract NN approximation errors in the adaptive neural control scheme. Most importantly, the finite-time stability in both the reaching phase and the sliding phase can be guaranteed by a Lyapunov-based approach. Finally, numerical simulations on the attitude tracking control of spacecraft in the presence of an unknown mass moment of inertia matrix, bounded external disturbances, and control input constraints are presented to demonstrate the performance of the proposed controller.

The Game of Cops and Robbers on Graphs

Abstract: This book is the first and only one of its kind on the topic of Cops and Robbers games, and more generally, on the field of vertex pursuit games on graphs The book is written in a lively and highly readable fashion, which should appeal to both senior undergraduates and experts in the field (and everyone in between) One of the main goals of the book is to bring together the key results in the field; as such, it presents structural, probabilistic, and algorithmic results on Cops and Robbers games Several recent and new results are discussed, along with a comprehensive set of references The book is suitable for self-study or as a textbook, owing in part to the over 200 exercises The reader will gain insight into all the main directions of research in the field and will be exposed to a number of open problems

Synthesis of three-dimensional calcium carbonate nanofibrous structure from eggshell using femtosecond laser ablation.

Abstract: Background Natural biomaterials from bone-like minerals derived from avian eggshells have been considered as promising bone substitutes owing to their biodegradability, abundance, and lower price in comparison with synthetic biomaterials. However, cell adhesion to bulk biomaterials is poor and surface modifications are required to improve biomaterial-cell interaction. Three-dimensional (3D) nanostructures are preferred to act as growth support platforms for bone and stem cells. Although there have been several studies on generating nanoparticles from eggshells, no research has been reported on synthesizing 3D nanofibrous structures.

System and methods for intraoperative guidance feedback

Abstract: Systems and methods for surgical guidance and image registration are provided, in which three-dimensional image data associated with an object or patient is registered to topological image data obtained using a surface topology imaging device. The surface topology imaging device may be rigidly attached to an optical position measurement system that also tracks fiducial markers on a movable instrument. The instrument may be registered to the topological image data, such that the topological image data and the movable instrument are registered to the three-dimensional image data. The three-dimensional image data may be CT or MRI data associated with a patient. The system may also co-register images pertaining to a surgical plan with the three-dimensional image data. In another aspect, the surface topology imaging device may be configured to directly track fiducial markers on a movable instrument. The fiducial markers may be tracked according to surface texture.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

Abstract: The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress-disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

Irradiation of gold nanoparticles by x-rays: Monte Carlo simulation of dose enhancements and the spatial properties of the secondary electrons production

Abstract: Purpose: The aim of this study is to understand the characteristics of secondary electrons generated from the interaction of gold nanoparticles (GNPs) with x-rays as a function of nanoparticle size and beam energy and thereby further the understanding of GNP-enhanced radiotherapy. Methods: The effective range, deflection angle, dose deposition, energy, and interaction processes of electrons produced from the interaction of x-rays with a GNP were calculated by Monte Carlo simulations. The GEANT4 code was used to simulate and track electrons generated from a 2, 50, and 100 nm diameter GNP when it is irradiated with a 50 kVp, 250 kVp, cobalt-60, and 6 MV photon beam in water. Results: When a GNP was present, depending on the beam energies used, secondary electron production was increased by 10- to 2000-fold compared to an absence of a GNP. Low-energy photon beams were much more efficient at interacting with the GNP by two to three orders of magnitude compared to MV energies and increased the deflection angle. GNPs with larger diameters also contributed more dose. The majority of the energy deposition was outside the GNP, rather than self-absorbed by the nanoparticle. The mean effective range of electron tracks for the beams tested rangedmore » from approximately 3 {mu}m to 1 mm. Conclusions: These simulated results yield important insights concerning the spatial distributions and elevated dose in GNP-enhanced radiotherapy. The authors conclude that the irradiation of GNP at lower photon energies will be more efficient for cell killing. This conclusion is consistent with published studies.« less

A review of mathematical models of influenza A infections within a host or cell culture: lessons learned and challenges ahead

Abstract: Most mathematical models used to study the dynamics of influenza A have thus far focused on the between-host population level, with the aim to inform public health decisions regarding issues such as drug and social distancing intervention strategies, antiviral stockpiling or vaccine distribution. Here, we investigate mathematical modeling of influenza infection spread at a different scale; namely that occurring within an individual host or a cell culture. We review the models that have been developed in the last decades and discuss their contributions to our understanding of the dynamics of influenza infections. We review kinetic parameters (e.g., viral clearance rate, lifespan of infected cells) and values obtained through fitting mathematical models, and contrast them with values obtained directly from experiments. We explore the symbiotic role of mathematical models and experimental assays in improving our quantitative understanding of influenza infection dynamics. We also discuss the challenges in developing better, more comprehensive models for the course of influenza infections within a host or cell culture. Finally, we explain the contributions of such modeling efforts to important public health issues, and suggest future modeling studies that can help to address additional questions relevant to public health.

Cascaded H-bridge multilevel converter multistring topology for large scale photovoltaic systems

Abstract: Large scale grid connected photovoltaic (PV) energy conversion systems have reached the megawatt level. This imposes new challenges on existing grid interface converter topologies and opens new opportunities to be explored. In this paper a new medium voltage multilevel-multistring configuration is introduced based on a three-phase cascaded H-bridge (CHB) converter and multiple string dc-dc converters. The proposed configuration enables a large increase of the total capacity of the PV system, while improving power quality and efficiency. The converter structure is very flexible and modular since it decouples the grid converter from the PV string converter, which allows to accomplish independent control goals. The main challenge of the proposed configuration is to handle the inherent power imbalances that occur not only between the different cells of one phase of the converter but also between the three phases. The control strategy to deal with these imbalances is also introduced in this paper. Simulation results of a 7-level CHB for a multistring PV system are presented to validate the proposed topology and control method.

Hierarchical Least Squares Identification for Linear SISO Systems With Dual-Rate Sampled-Data

Abstract: This technical note studies identification problems for dual-rate sampled-data linear systems with noises. A hierarchical least squares (HLS) identification algorithm is presented to estimate the parameters of the dual-rate ARMAX models. The basic idea is to decompose the identification model of a dual-rate system into several sub-identification models with smaller dimensions and fewer parameters. The proposed algorithm is more computationally efficient than the recursive least squares (RLS) algorithm since the RLS algorithm requires computing the covariance matrix of large sizes, while the HLS algorithm deals with the covariance matrix of small sizes. Compared with our previous work, a detailed study of the HLS algorithm is conducted in this technical note. The performance analysis and simulation results confirm that the estimation accuracy of the proposed algorithm are close to that of the RLS algorithm, but the proposed algorithm retains much less computational burden.

Equivalent-Input-Disturbance Approach—Analysis and Application to Disturbance Rejection in Dual-Stage Feed Drive Control System

Abstract: This paper deals with the high-precision positioning control of a dual-stage feed drive. The design of the control system is based on the equivalent input-disturbance (EID) approach to improve the disturbance rejection performance. An analysis of the EID approach reveals the mechanism of disturbance rejection. The design procedure is illustrated by a numerical example. Simulation results show that the EID control system not only rejects disturbances, but also suppresses uncertainties and nonlinearities in the plant. Design and simulation results for the example are also employed to compare our method with the disturbance observer method, and to demonstrate the validity of our method.

Cognitive-behavioral therapy for PTSD and depression symptoms reduces risk for future intimate partner violence among interpersonal trauma survivors.

Abstract: Objective: Women who develop symptoms of posttraumatic stress disorder (PTSD) and depression subsequent to interpersonal trauma are at heightened risk for future intimate partner violence (IPV) victimization. Cognitive–behavioral therapy (CBT) is effective in reducing PTSD and depression symptoms, yet limited research has investigated the effectiveness of CBT in reducing risk for future IPV among interpersonal trauma survivors. Method: This study examined the effect of CBT for PTSD and depressive symptoms on the risk of future IPV victimization in a sample of women survivors of interpersonal violence. The current sample included 150 women diagnosed with PTSD secondary to an array of interpersonal traumatic events; they were participating in a randomized clinical trial of different forms of cognitive processing therapy for the treatment of PTSD. Participants were assessed at 9 time points as part of the larger trial: pretreatment, 6 times during treatment, posttreatment, and 6-month follow-up. Results: As hypothesized, reductions in PTSD and in depressive symptoms during treatment were associated with a decreased likelihood of IPV victimization at a 6-month follow-up even after controlling for recent IPV (i.e., IPV from a current partner within the year prior to beginning the study) and prior interpersonal traumas. Conclusions: These findings highlight the importance of identifying and treating PTSD and depressive symptoms among interpersonal trauma survivors as a method for reducing risk for future IPV.

A model for cost-benefit analysis of construction and demolition waste management throughout the waste chain

Abstract: Jointly organized by Government of Maldives Ministry of Tourism, Government of Maldives Ministry of the Environment, and Government of Japan Ministry of the Environment and United Nations Centre for Regional Development (UNCRD)

Optical coherence elastography: current status and future applications.

Abstract: Optical coherence tomography (OCT) has several advantages over other imaging modalities, such as angiography and ultrasound, due to its inherently high in vivo resolution, which allows for the identification of morphological tissue structures. Optical coherence elastography (OCE) benefits from the superior spatial resolution of OCT and has promising applications, including cancer diagnosis and the detailed characterization of arterial wall biomechanics, both of which are based on the elastic properties of the tissue under investigation. We present OCE principles based on techniques associated with static and dynamic tissue excitation, and their corresponding elastogram image-reconstruction algorithms are reviewed. OCE techniques, including the development of intravascular- or catheter-based OCE, are in their early stages of development but show great promise for surgical oncology or intravascular cardiology applications.

Fat crystals and water-in-oil emulsion stability

Abstract: Products such as cosmetics, pharmaceuticals, and crude oil often exist as water-in-oil (W/O) emulsions during their processing or in final form. In many cases, their dispersed aqueous phase is encased in a crystal network and/or by interfacially-adsorbed (‘Pickering’) particles [paraffins, triacylglycerols, polymers, etc.] that promote emulsion kinetic stability by hindering droplet–droplet contact, coalescence and macroscopic phase separation. In processed foods, important questions remain regarding whether a continuous phase fat crystal network or Pickering crystal provides better stabilization. This review explores the following factors related to crystal-stabilized W/O emulsions: i) the key properties dictating fat crystal spatial distribution (at the interface or in the continuous phase); ii) how temperature and freeze–thaw emulsion destabilization are intimately linked with fat crystal spatial distribution, and; iii) why oil-soluble surfactant interactions with the continuous oil phase influence fat crystal wettability and emulsifier efficacy. It is shown that these parameters strongly govern W/O emulsion formation and stability.

Does Female Directorship on Independent Audit Committees Constrain Earnings Management

Abstract: This study examines whether the gender of the directors on fully independent audit committees affects the ability of the committees in constraining earnings management and thus their effectiveness in overseeing the financial reporting process. Using a sample of 525 firm-year observations over the period 2003 to 2005, we are unable to identify an association between the proportion of female directors on audit committees and the extent of earnings management.

Toronto’s Urban Heat Island—Exploring the Relationship between Land Use and Surface Temperature

Abstract: The urban heat island effect is linked to the built environment and threatens human health during extreme heat events. In this study, we analyzed whether characteristic land uses within an urban area are associated with higher or lower surface temperatures, and whether concentrations of “hot” land uses exacerbate this relationship. Zonal statistics on a thermal remote sensing image for the City of Toronto revealed statistically significant differences between high average temperatures for commercial and resource/industrial land use (29.1 °C), and low average temperatures for parks and recreational land (25.1 °C) and water bodies (23.1 °C). Furthermore, higher concentrations of either of these land uses were associated with more extreme surface temperatures. We also present selected neighborhoods to illustrate these results. The paper concludes by recommending that municipal planners and decision-makers formulate policies and regulations that are specific to the problematic land uses, in order to mitigate extreme heat.

Design, Evaluation, and Translation of Nursing Interventions

Abstract: Nurse-led intervention research is a core component of the global initiative to improve quality of care. Though research in this area has already contributed much to the advancement of patient care, future strides depend on the dissemination of practical, how-to instruction on this important area of research. Design, Evaluation, and Translation of Nursing Interventions aids in this endeavour by presenting both general approaches and specific methods for developing nursing interventions. Logically organized to facilitate ease of use, the book is divided into four sections. The introduction provides a firm grounding in intervention science by situating it within the broader topics of evidence-based practice, client-centred care, and quality of care. Section Two describes each step of intervention design, including correct identification of the health issue or problem, clarification of the elements comprising an intervention, and application of theory. Section Three is centred on implementation, highlighting such topics as development of the intervention manual, training interventionists, and intervention fidelity. The book concludes with methods to evaluate interventions enacted and suggestions for their translation into practice.

Multiple perspectives on engaging future engineers

Abstract: Background Engaging future engineers is a central topic in everyday conversations on engineering education. Considerable investments have been made to make engineering more engaging, recruit and retain aspiring engineers, and to design an education to prepare future engineers. However, the impact of these efforts has been less than intended. It is imperative that the community reflects on progress and sets a more effective path for the future. Purpose The purpose of this article is to map a new innovation landscape for what it means to engage future engineers. This is a theoretically grounded divergent-thinking effort to enable a broader space of high impact innovations for engaging future engineers. Scope/Method A multiple perspectives methodology drawing from innovation, cross-disciplinary, and boundary work frameworks was used to make visible multiple facets of engaging future engineers. Scholars from diverse communities of thought and discourse were selected to present interparadigmatic perspectives, act as boundary agents, challenge and transform current ways of thinking, and illustrate new opportunities for engineering education innovation. Conclusions A new innovation landscape for engaging future engineers is needed, one that emphasizes epistemological development and social justice, new configurations on engineering thinking and connecting to the formative years of development, the entwinement of engineering knowing and being, and mutually informing consequences for opening up a broader space for innovation. We also need to adopt strategies and tools for using a multiple perspectives approach to better understand complex engineering education problems.

Toward Early-Warning Detection of Gravitational Waves from Compact Binary Coalescence

Abstract: Rapid detection of compact binary coalescence (CBC) with a network of advanced gravitational-wave detectors will offer a unique opportunity for multi-messenger astronomy. Prompt detection alerts for the astronomical community might make it possible to observe the onset of electromagnetic emission from (CBC). We demonstrate a computationally practical filtering strategy that could produce early-warning triggers before gravitational radiation from the final merger has arrived at the detectors.

Mirroring in Dance/Movement Therapy: Potential mechanisms behind empathy enhancement

Abstract: Mirroring, an exercise practiced in Dance/Movement Therapy (DMT), is considered by practitioners and patients to enhance emotional understanding and empathy for others. Mirroring involves imitation by the therapist of movements, emotions, or intentions implied by a client's movement, and is commonly practiced in order to enhance empathy of the therapist for the client. Despite enthusiastic claims for its effectiveness, a clear theoretical framework that would explain the effects of mirroring on empathy has not yet been presented, and empirical research on the topic is generally lacking. In this review, we propose that mirroring in DMT enhances understanding of others’ emotional intentions through enhanced use of mirror neuron circuitry. Research on the mirror neuron system (MNS) suggests that the brain areas involved in perception and production of movement overlap, and that these brain areas are also involved in the understanding of movement intention ( Rizzolatti & Craighero, 2004 ). One important route to emotion recognition involves a neural simulation of another person's emotional actions in order to infer the intentions behind those actions, and empathize with them. Future research is proposed in order to systematically explore the effectiveness of mirroring in dance therapy, the neural mechanisms behind it, and its applicability to patient populations who have problems with empathy.