Showing papers by "Lehigh University published in 2010"

The Impact of Board Diversity and Gender Composition on Corporate Social Responsibility and Firm Reputation

Abstract: This article explores how the diversity of board resources and the number of women on boards affect firms’ corporate social responsibility (CSR) ratings, and how, in turn, CSR influences corporate reputation. In addition, this article examines whether CSR ratings mediate the relationships among board resource diversity, gender composition, and corporate reputation. The OLS regression results using lagged data for independent and control variables were statistically significant for the gender composition hypotheses, but not for the resource diversity-based hypotheses. CSR ratings had a positive impact on reputation and mediated the relationship between the number of women on the board and corporate reputation.

Empirical study of topic modeling in Twitter

Abstract: Social networks such as Facebook, LinkedIn, and Twitter have been a crucial source of information for a wide spectrum of users. In Twitter, popular information that is deemed important by the community propagates through the network. Studying the characteristics of content in the messages becomes important for a number of tasks, such as breaking news detection, personalized message recommendation, friends recommendation, sentiment analysis and others. While many researchers wish to use standard text mining tools to understand messages on Twitter, the restricted length of those messages prevents them from being employed to their full potential.We address the problem of using standard topic models in micro-blogging environments by studying how the models can be trained on the dataset. We propose several schemes to train a standard topic model and compare their quality and effectiveness through a set of carefully designed experiments from both qualitative and quantitative perspectives. We show that by training a topic model on aggregated messages we can obtain a higher quality of learned model which results in significantly better performance in two real-world classification problems. We also discuss how the state-of-the-art Author-Topic model fails to model hierarchical relationships between entities in Social Media.

Global peatland dynamics since the Last Glacial Maximum

Abstract: [1] Here we present a new data synthesis of global peatland ages, area changes, and carbon (C) pool changes since the Last Glacial Maximum, along with a new peatland map and total C pool estimates. The data show different controls of peatland expansion and C accumulation in different regions. We estimate that northern peatlands have accumulated 547 (473–621) GtC, showing maximum accumulation in the early Holocene in response to high summer insolation and strong summer – winter climate seasonality. Tropical peatlands have accumulated 50 (44–55) GtC, with rapid rates about 8000–4000 years ago affected by a high and more stable sea level, a strong summer monsoon, and before the intensification of El Nino. Southern peatlands, mostly in Patagonia, South America, have accumulated 15 (13–18) GtC, with rapid accumulation during the Antarctic Thermal Maximum in the late glacial, and during the mid-Holocene thermal maximum. This is the first comparison of peatland dynamics among these global regions. Our analysis shows that a diversity of drivers at different times have significantly impacted the global C cycle, through the contribution of peatlands to atmospheric CH4 budgets and the history of peatland CO2 exchange with the atmosphere.

The Effects of Child Abuse and Exposure to Domestic Violence on Adolescent Internalizing and Externalizing Behavior Problems.

Abstract: This study examines the effects of child abuse and domestic violence exposure in childhood on adolescent internalizing and externalizing behaviors Data for this analysis are from the Lehigh Longitudinal Study, a prospective study of 457 youth addressing outcomes of family violence and resilience in individuals and families Results show that child abuse, domestic violence, and both in combination (ie, dual exposure) increase a child’s risk for internalizing and externalizing outcomes in adolescence When accounting for risk factors associated with additional stressors in the family and surrounding environment, only those children with dual exposure had an elevated risk of the tested outcomes compared to non-exposed youth However, while there were some observable differences in the prediction of outcomes for children with dual exposure compared to those with single exposure (ie, abuse only or exposure to domestic violence only), these difference were not statistically significant Analyses showed that the effects of exposure for boys and girls are statistically comparable

Target Localization Accuracy Gain in MIMO Radar-Based Systems

Abstract: This paper presents an analysis of target localization accuracy, attainable by the use of multiple-input multiple-output (MIMO) radar systems, configured with multiple transmit and receive sensors, widely distributed over an area. The Cramer-Rao lower bound (CRLB) for target localization accuracy is developed for both coherent and noncoherent processing. Coherent processing requires a common phase reference for all transmit and receive sensors. The CRLB is shown to be inversely proportional to the signal effective bandwidth in the noncoherent case, but is approximately inversely proportional to the carrier frequency in the coherent case. We further prove that optimization over the sensors' positions lowers the CRLB by a factor equal to the product of the number of transmitting and receiving sensors. The best linear unbiased estimator (BLUE) is derived for the MIMO target localization problem. The BLUE's utility is in providing a closed-form localization estimate that facilitates the analysis of the relations between sensors locations, target location, and localization accuracy. Geometric dilution of precision (GDOP) contours are used to map the relative performance accuracy for a given layout of radars over a given geographic area.

Long Range Interactions in Nanoscale Science.

Abstract: Our understanding of the ``long range'' electrodynamic, electrostatic, and polar interactions that dominate the organization of small objects at separations beyond an interatomic bond length is reviewed From this basic-forces perspective, a large number of systems are described from which one can learn about these organizing forces and how to modulate them The many practical systems that harness these nanoscale forces are then surveyed The survey reveals not only the promise of new devices and materials, but also the possibility of designing them more effectively

NOrec: streamlining STM by abolishing ownership records

Abstract: Drawing inspiration from several previous projects, we present an ownership-record-free software transactional memory (STM) system that combines extremely low overhead with unusually clean semantics. While unlikely to scale to hundreds of active threads, this "NOrec" system offers many appealing features: very low fast-path latency--as low as any system we know of that admits concurrent updates; publication and privatization safety; livelock freedom; a small, constant amount of global metadata, and full compatibility with existing data structure layouts; no false conflicts due to hash collisions; compatibility with both managed and unmanaged languages, and both static and dynamic compilation; and easy acccommodation of closed nesting, inevitable (irrevocable) transactions, and starvation avoidance mechanisms. To the best of our knowledge, no extant STM system combines this set of features.While transactional memory for processors with hundreds of cores is likely to require hardware support, software implementations will be required for backward compatibility with current and near-future processors with 2--64 cores, as well as for fall-back in future machines when hardware resources are exhausted. Our experience suggests that NOrec may be an ideal candidate for such a software system. We also observe that it has considerable appeal for use within the operating system, and in systems that require both closed nesting and publication safety.

Alliance Portfolio Diversity and Firm Performance

Abstract: In this paper, we offer a comprehensive alliance portfolio diversity construct that includes partner, functional, and governance diversity. Grounding our work primarily with the resource and dynamic capabilities-based views, we argue that increased diversity in partners’ industry, organizational, and national background will incur added complexity and coordination costs but will provide broadened resource and learning benefits. Increased functional diversity results in a more balanced portfolio of exploration and exploitation activities that expands the firm’s knowledge base while increased governance diversity inhibits learning and routine building. Hypotheses were tested with alliance portfolio and performance data for 138 multinational firms in the global automobile industry during the twenty-year period from 1985 to 2005. We found alliance portfolios with greater organizational and functional diversity and lower governance diversity were related to higher firm performance while industry diversity had a U-shaped relationship with firm performance. We suggest firms manage their alliances with a portfolio perspective, seeking to maximize resource and learning benefits by collaborating with a variety of organizations in various value chain activities while minimizing managerial costs through a focused set of governance structures.

Detection of noninteracting single domain particles using first-order reversal curve diagrams

Abstract: We present a highly sensitive and accurate method for quantitative detection and characterization of noninteracting or weakly interacting uniaxial single domain particles (UNISD) in rocks and sediments. The method is based on high-resolution measurements of first-order reversal curves (FORCs). UNISD particles have a unique FORC signature that can be used to isolate their contribution among other magnetic components. This signature has a narrow ridge along the Hc axis of the FORC diagram, called the central ridge, which is proportional to the switching field distribution of the particles. Therefore, the central ridge is directly comparable with other magnetic measurements, such as remanent magnetization curves, with the advantage of being fully selective to SD particles, rather than other magnetic components. This selectivity is unmatched by other magnetic unmixing methods, and offers useful applications ranging from characterization of SD particles for paleointensity studies to detecting magnetofossils and ultrafine authigenically precipitated minerals in sediments.

Interior Point Methods for Nonlinear Optimization

Abstract: Interior-point methods (IPMs) are among the most efficient methods for solving linear, and also wide classes of other convex optimization problems. Since the path-breaking work of Karmarkar [48], much research was invested in IPMs. Many algorithmic variants were developed for Linear Optimization (LO). The new approach forced to reconsider all aspects of optimization problems. Not only the research on algorithms and complexity issues, but implementation strategies, duality theory and research on sensitivity analysis got also a new impulse. After more than a decade of turbulent research, the IPM community reached a good understanding of the basics of IPMs. Several books were published that summarize and explore different aspects of IPMs. The seminal work of Nesterov and Nemirovski [63] provides the most general framework for polynomial IPMs for convex optimization. Den Hertog [42] gives a thorough survey of primal and dual path-following IPMs for linear and structured convex optimization problems. Jansen [45] discusses primal-dual target following algorithms for linear optimization and complementarity problems.Wright [93] also concentrates on primal-dual IPMs, with special attention on infeasible IPMs, numerical issues and local, asymptotic convergence properties. The volume [80] contains 13 survey papers that cover almost all aspects of IPMs, their extensions and some applications. The book of Ye [96] is a rich source of polynomial IPMs not only for LO, but for convex optimization problems as well. It extends the IPM theory to derive bounds and approximations for classes of nonconvex optimization problems as well. Finally, Roos, Terlaky and Vial [72] present a thorough treatment of the IPM based theory - duality, complexity, sensitivity analysis - and wide classes of IPMs for LO.

Alliance portfolio diversity and firm performance

Abstract: In this paper, we offer a comprehensive alliance portfolio diversity construct that includes partner, functional, and governance diversity. Grounding our work primarily with the resource- and dynamic capabilities-based views, we argue that increased diversity in partners' industry, organizational, and national background will incur added complexity and coordination costs but will provide broadened resource and learning benefits. Increased functional diversity results in a more balanced portfolio of exploration and exploitation activities that expands the firm's knowledge base while increased governance diversity inhibits learning and routine building. Hypotheses were tested with alliance portfolio and performance data for 138 multinational firms in the global automobile industry during the twenty-year period from 1985 to 2005. We found alliance portfolios with greater organizational and functional diversity and lower governance diversity were related to higher firm performance while industry diversity had a U-shaped relationship with firm performance. We suggest firms manage their alliances with a portfolio perspective, seeking to maximize resource and learning benefits by collaborating with a variety of organizations in various value chain activities while minimizing managerial costs through a focused set of governance structures. Copyright © 2010 John Wiley & Sons, Ltd.

A mechanically stabilized receptor–ligand flex-bond important in the vasculature

Abstract: Haemostasis in the arteriolar circulation mediated by von Willebrand factor (VWF) binding to platelets is an example of an adhesive interaction that must withstand strong hydrodynamic forces acting on cells. VWF is a concatenated, multifunctional protein that has binding sites for platelets as well as subendothelial collagen. Binding of the A1 domain in VWF to the glycoprotein Ib alpha subunit (GPIbalpha) on the surface of platelets mediates crosslinking of platelets to one another and the formation of a platelet plug for arterioles. The importance of VWF is illustrated by its mutation in von Willebrand disease, a bleeding diathesis. Here, we describe a novel mechanochemical specialization of the A1-GPIbalpha bond for force-resistance. We have developed a method that enables, for the first time, repeated measurements of the binding and unbinding of a receptor and ligand in a single molecule (ReaLiSM). We demonstrate two states of the receptor-ligand bond, that is, a flex-bond. One state is seen at low force; a second state begins to engage at 10 pN with a approximately 20-fold longer lifetime and greater force resistance. The lifetimes of the two states, how force exponentiates lifetime, and the kinetics of switching between the two states are all measured. For the first time, single-molecule measurements on this system are in agreement with bulk phase measurements. The results have important implications not only for how platelets bound to VWF are able to resist force to plug arterioles, but also how increased flow activates platelet plug formation.

Point of Care Testing

Abstract: DATA SYNTHESIS: Point-of-care testing devices and technology are increasingly used in the delivery of care and therapeutic decision making. No studies have evaluated the impact of point-of-care testing, by itself, on patient care and outcomes. All studies have incorporated point-of-care testing with changes in the way patient care is delivered and have shown significant improvements when this approach is taken. The cost of point-of-care testing on a per test basis is sometimes greater than traditional laboratory testing, but that increased cost may be offset by improvements in the management of patient care, improvements in patient outcomes, and decreased utilization of the healthcare system. Point-of-care testing has been used successfully by pharmacists in disease management programs. Various government regulations and legislation impact the use of point-of-care testing.

A stellar rotation census of b stars: from zams to tams

Abstract: Two recent observing campaigns provide us with moderate dispersion spectra of more than 230 cluster and 370 field B stars. Combining them and the spectra of the B stars from our previous investigations (~430 cluster and ~100 field B stars) yields a large, homogeneous sample for studying the rotational properties of B stars. We derive the projected rotational velocity Vsin i, effective temperature, gravity, mass, and critical rotation speed V crit for each star. We find that the average Vsin i is significantly lower among field stars because they are systematically more evolved and spun down than their cluster counterparts. The rotational distribution functions of V eq/V crit for the least evolved B stars show that lower mass B stars are born with a larger proportion of rapid rotators than higher mass B stars. However, the upper limit of V eq/V crit that may separate normal B stars from emission-line Be stars (where rotation promotes mass loss into a circumstellar disk) is smaller among the higher mass B stars. We compare the evolutionary trends of rotation (measured according to the polar gravity of the star) with recent models that treat internal mixing. The spin-down rates observed in the high-mass subset (~9 M ☉) agree with predictions, but the rates are larger for the low-mass group (~3 M ☉). The faster spin-down in the low-mass B stars matches well with the predictions based on conservation of angular momentum in individual spherical shells. Our results suggest that the fastest rotators (that probably correspond to the emission-line Be stars) are probably formed by evolutionary spin-up (for the more massive stars) and by mass transfer in binaries (for the full range of B star masses).

Social Story™ Interventions for Students with Autism Spectrum Disorders: A Meta-Analysis

Abstract: A meta-analysis of single-subject research was conducted, examining the use of Social Stories™ and the role of a comprehensive set of moderator variables (intervention and participant characteristics) on intervention outcomes. While Social Stories had low to questionable overall effectiveness, they were more effective when addressing inappropriate behaviors than when teaching social skills. Social Stories also seemed to be associated with improved outcomes when used in general education settings and with target children as their own intervention agents. The role of other variables of interest, such as participants’ age, diagnosis, and skill development, the format of Social Stories, the length of the intervention, and the use of assessment (e.g., comprehension checks) also was explored.

Target Velocity Estimation and Antenna Placement for MIMO Radar With Widely Separated Antennas

Abstract: This paper studies the velocity estimation performance for multiple-input multiple-output (MIMO) radar with widely spaced antennas. We derive the Cramer-Rao bound (CRB) for velocity estimation and study the optimized system/configuration design based on CRB. General results are presented for an extended target with reflectivity varying with look angle. Then detailed analysis is provided for a simplified case, assuming an isotropic scatterer. For given transmitted signals, optimal antenna placement is analyzed in the sense of minimizing the CRB of the velocity estimation error. We show that when all antennas are located at approximately the same distance from the target, symmetrical placement is optimal and the relative position of transmitters and receivers can be arbitrary under the orthogonal received signal assumption. In this case, it is also shown that for MIMO radar with optimal placement, velocity estimation accuracy can be improved by increasing either the signal time duration or the product of the number of transmit and receive antennas.

MIMO Radar Moving Target Detection in Homogeneous Clutter

Abstract: A multiple-input multiple-output (MIMO) radar approach employing widely dispersed transmit and receive antennas is studied for the detection of moving targets. The MIMO radar transmits orthogonal waveforms from the different transmit antennas so these waveforms can be separated at each receive antenna. For a moving target in colored Gaussian noise-plus-clutter, we quantify the gains from having widely dispersed antennas that allow the overall system to "view" the target simultaneously from several different directions. The MIMO radar performance is contrasted with that of a traditional phased-array approach, which employs closely spaced antennas for this purpose. The MIMO radar approach is well suited to handle targets that have small radial velocities for scenarios in which colocated sensors cannot separate the target from the background clutter. Both a centralized processing and a simple distributed processing form of the MIMO radar approach are developed and studied, and the gains from the centralized version, which come at the price of additional complexity, are clearly demonstrated and explained intuitively. The constant false alarm rate (CFAR) property of an adaptive version of the MIMO moving target detector is also demonstrated for homogeneous clutter.

The Uses of Evidence for Educational Policymaking: Global Contexts and International Trends:

Abstract: the past 150 years, educational systems have expanded and become integrally linked with economic, political, and social status in modern nation-states (see Kamens, Meyer, & Benavot, 1996). As the stakes for education have risen, so has the call for more and improved use of scientific evidence as a basis for educational policymaking (Luke, 2003; Slavin, 2002). The rise in the use of scientific evidence for educational policymaking rests on two common beliefs: One is the belief that school knowledge is abstract and universal, and the other is the belief that empirical evidence is an efficient indicator of knowledge and learning. As a result, there are serious educational policymaking consequences for individuals and schools tied to evidence (Olson, 2006). Evidence from averaged scores on international assessments of math and science achievement in particular have become important indicators of national political and economic strength, but there are many different kinds of evidence to consider (LeTendre, Baker, Akiba, & Wiseman, 2001; Wiseman & Baker, 2005). For example, high-stakes consequences resulting from averaged academic achievement scores exist for students and schools in the United States but even more so in other countries, such as Japan (LeTendre, 1999; E. Smith, 2005). However, how and why evidence is used for educational policymaking both in the United States and around the world are the larger questions this chapter addresses. To investigate the uses of evidence for educational policymaking, this volume and this chapter ask two fundamental orienting questions: Why use evidence in educational policymaking? And why is evidence-based educational policymaking a global phenomenon? The answer to the first orienting question serves as a foundation for introducing relevant macrotheoretical perspectives and exploring the motivations and agendas that drive educational policy and decision making. The answer to the

Rapid deglacial and early Holocene expansion of peatlands in Alaska.

Abstract: Northern peatlands represent one of the largest biospheric carbon (C) reservoirs; however, the role of peatlands in the global carbon cycle remains intensely debated, owing in part to the paucity of detailed regional datasets and the complexity of the role of climate, ecosystem processes, and environmental factors in controlling peatland C dynamics. Here we used detailed C accumulation data from four peatlands and a compilation of peatland initiation ages across Alaska to examine Holocene peatland dynamics and climate sensitivity. We find that 75% of dated peatlands in Alaska initiated before 8,600 years ago and that early Holocene C accumulation rates were four times higher than the rest of the Holocene. Similar rapid peatland expansion occurred in West Siberia during the Holocene thermal maximum (HTM). Our results suggest that high summer temperature and strong seasonality during the HTM in Alaska might have played a major role in causing the highest rates of C accumulation and peatland expansion. The rapid peatland expansion and C accumulation in these vast regions contributed significantly to the peak of atmospheric methane concentrations in the early Holocene. Furthermore, we find that Alaskan peatlands began expanding much earlier than peatlands in other regions, indicating an important contribution of these peatlands to the pre-Holocene increase in atmospheric methane concentrations.

Current injection efficiency induced efficiency-droop in InGaN quantum well light-emitting diodes

Abstract: Current injection efficiency and its impact on efficiency-droop in InGaN single quantum well (QW) based light-emitting diodes (LEDs) are investigated. The analysis is based on current continuity relation for drift and diffusion carrier transport across the QW-barrier system. A self-consistent 6-band k · p method is used to calculate the band structure for InGaN QW. The analysis indicates that the internal quantum efficiency in the conventional 24-A In 0.28 Ga 0.72 N–GaN QW structure reaches its peak at low injection current density and reduces gradually with further increase in current due to the large carrier thermionic emission. Structures combining 24-A In 0.28 Ga 0.72 N QW with 15-A Al 0.1 Ga 0.9 N barriers show slight reduction in quenching of the injection efficiency as current density increases. The use of 15-A Al 0.83 In 0.17 N barriers shows significant reduction in efficiency-droop (10% reduction of the internal quantum efficiency at current density of 620 A/cm 2 ). Thus, InGaN QWs employing thin layers of larger bandgap AlInN barriers suppress the efficiency-droop phenomenon significantly.

Noncoherent MIMO Radar for Location and Velocity Estimation: More Antennas Means Better Performance

Abstract: This paper presents an analysis of the joint estimation of target location and velocity using a multiple-input multiple-output (MIMO) radar employing noncoherent processing for a complex Gaussian extended target. A MIMO radar with M transmit and N receive antennas is considered. To provide insight, we focus on a simplified case first, assuming orthogonal waveforms, temporally and spatially white noise-plus-clutter, and independent reflection coefficients. Under these simplifying assumptions, the maximum-likelihood (ML) estimate is analyzed, and a theorem demonstrating the asymptotic consistency, large MN , of the ML estimate is provided. Numerical investigations, given later, indicate similar behavior for some reasonable cases violating the simplifying assumptions. In these initial investigations, we study unconstrained systems, in terms of complexity and energy, where each added transmit antenna employs a fixed energy so that the total transmitted energy is allowed to increase as we increase the number of transmit antennas. Following this, we also look at constrained systems, where the total system energy and complexity are fixed. To approximate systems of fixed complexity in an abstract way, we restrict the total number of antennas employed to be fixed. Here, we show numerical examples which indicate a preference for receive antennas, similar to MIMO communications, but where systems with multiple transmit antennas yield the smallest possible mean-square error (MSE). The joint Cramer-Rao bound (CRB) is calculated and the MSE of the ML estimate is analyzed. It is shown for some specific numerical examples that the signal-to-clutter-plus-noise ratio (SCNR) threshold, indicating the SCNRs above which the MSE of the ML estimate is reasonably close to the CRB, can be lowered by increasing MN. The noncoherent MIMO radar ambiguity function (AF) is developed in two different ways and illustrated by examples. It is shown for some specific examples that the size of the product MN controls the levels of the sidelobes of the AF.

The Donnan membrane principle: opportunities for sustainable engineered processes and materials.

Abstract: The Donnan membrane principle can permit many engineered processes and materials to achieve better sustainability.

Automatic image annotation using group sparsity

Abstract: Automatically assigning relevant text keywords to images is an important problem. Many algorithms have been proposed in the past decade and achieved good performance. Efforts have focused upon model representations of keywords, but properties of features have not been well investigated. In most cases, a group of features is preselected, yet important feature properties are not well used to select features. In this paper, we introduce a regularization based feature selection algorithm to leverage both the sparsity and clustering properties of features, and incorporate it into the image annotation task. A novel approach is also proposed to iteratively obtain similar and dissimilar pairs from both the keyword similarity and the relevance feedback. Thus keyword similarity is modeled in the annotation framework. Numerous experiments are designed to compare the performance between features, feature combinations and regularization based feature selection methods applied on the image annotation task, which gives insight into the properties of features in the image annotation task. The experimental results demonstrate that the group sparsity based method is more accurate and stable than others.

RepFinder: finding approximately repeated scene elements for image editing

Abstract: Repeated elements are ubiquitous and abundant in both manmade and natural scenes. Editing such images while preserving the repetitions and their relations is nontrivial due to overlap, missing parts, deformation across instances, illumination variation, etc. Manually enforcing such relations is laborious and error-prone. We propose a novel framework where user scribbles are used to guide detection and extraction of such repeated elements. Our detection process, which is based on a novel boundary band method, robustly extracts the repetitions along with their deformations. The algorithm only considers the shape of the elements, and ignores similarity based on color, texture, etc. We then use topological sorting to establish a partial depth ordering of overlapping repeated instances. Missing parts on occluded instances are completed using information from other instances. The extracted repeated instances can then be seamlessly edited and manipulated for a variety of high level tasks that are otherwise difficult to perform. We demonstrate the versatility of our framework on a large set of inputs of varying complexity, showing applications to image rearrangement, edit transfer, deformation propagation, and instance replacement.