Showing papers by "University of Arkansas published in 2014"

Parity–time symmetry and variable optical isolation in active–passive-coupled microresonators

Abstract: On-chip parity–time-symmetric optics is experimentally demonstrated at a wavelength of 1,550 nm in two directly coupled, high-Q silica microtoroid resonators with balanced effective gain and loss. Switchable optical isolation with a nonreciprocal isolation ratio between −8 dB and +8 dB is also shown. The findings will be useful for potential applications in optical isolators, on-chip light control and optical communications. Compound-photonic structures with gain and loss1 provide a powerful platform for testing various theoretical proposals on non-Hermitian parity–time-symmetric quantum mechanics2,3,4,5 and initiate new possibilities for shaping optical beams and pulses beyond conservative structures. Such structures can be designed as optical analogues of complex parity–time-symmetric potentials with real spectra. However, the beam dynamics can exhibit unique features distinct from conservative systems due to non-trivial wave interference and phase-transition effects. Here, we experimentally realize parity–time-symmetric optics on a chip at the 1,550 nm wavelength in two directly coupled high-Q silica-microtoroid resonators with balanced effective gain and loss. With this composite system, we further implement switchable optical isolation with a non-reciprocal isolation ratio from −8 dB to +8 dB, by breaking time-reversal symmetry with gain-saturated nonlinearity in a large parameter-tunable space. Of importance, our scheme opens a door towards synthesizing novel microscale photonic structures for potential applications in optical isolators, on-chip light control and optical communications.

Benchmarks for Science Literacy

Abstract: Benchmarks emerged after a three year research study sponsored by the AAAS called Project 2061. This name is inspired by Halley’s Comet which was last seen in 1985 when work began on the project. It relates to the scientific and technological changes children entering school in 1985 might expect to see before the comet returns in 2061.

A Brief Vestibular/Ocular Motor Screening (VOMS) Assessment to Evaluate Concussions: Preliminary Findings

Abstract: Background:Vestibular and ocular motor impairments and symptoms have been documented in patients with sport-related concussions. However, there is no current brief clinical screen to assess and monitor these issues.Purpose:To describe and provide initial data for the internal consistency and validity of a brief clinical screening tool for vestibular and ocular motor impairments and symptoms after sport-related concussions.Study Design:Cross-sectional study; Level of evidence, 2.Methods:Sixty-four patients, aged 13.9 ± 2.5 years and seen approximately 5.5 ± 4.0 days after a sport-related concussion, and 78 controls were administered the Vestibular/Ocular Motor Screening (VOMS) assessment, which included 5 domains: (1) smooth pursuit, (2) horizontal and vertical saccades, (3) near point of convergence (NPC) distance, (4) horizontal vestibular ocular reflex (VOR), and (5) visual motion sensitivity (VMS). Participants were also administered the Post-Concussion Symptom Scale (PCSS).Results:Sixty-one percent of...

Un)ethical behavior in organizations.

Abstract: This review spotlights research related to ethical and unethical behavior in organizations. It builds on previous reviews and meta-analyses of the literature on (un)ethical behavior in organizations and discusses recent advances in the field. The review emphasizes how this research speaks to the influence of the organizational context on (un)ethical behavior, proceeding from a more macro to a more micro view on (un)ethical behavior and covering ethical infrastructures, interpersonal influences, individual differences, and cognitive and affective processes. The conclusion highlights opportunities for future research.

Programme for International Student Assessment (PISA)

Abstract: Since the assessment program began in 1997, over 70 countries have participated at least once. Every three years, a randomly selected group of 15-year-old students take the test, which primarily focuses on one key subject.

Achieving k-anonymity in privacy-aware location-based services

Abstract: Location-Based Service (LBS) has become a vital part of our daily life. While enjoying the convenience provided by LBS, users may lose privacy since the untrusted LBS server has all the information about users in LBS and it may track them in various ways or release their personal data to third parties. To address the privacy issue, we propose a Dummy- Location Selection (DLS) algorithm to achieve k-anonymity for users in LBS. Different from existing approaches, the DLS algorithm carefully selects dummy locations considering that side information may be exploited by adversaries. We first choose these dummy locations based on the entropy metric, and then propose an enhanced-DLS algorithm, to make sure that the selected dummy locations are spread as far as possible. Evaluation results show that the proposed DLS algorithm can significantly improve the privacy level in terms of entropy. The enhanced-DLS algorithm can enlarge the cloaking region while keeping similar privacy level as the DLS algorithm. I. INTRODUCTION With the rapid development of mobile devices and social networks, Location-Based Service (LBS) has become a vital part in our daily activities in recent years. With smartphones or tablets, users can download location-based applications from Apple Store or Google Play Store. With the help of these

Quantum anomalous Hall effect in graphene proximity coupled to an antiferromagnetic insulator

Abstract: We propose realizing the quantum anomalous Hall effect by proximity coupling graphene to an antiferromagnetic insulator that provides both broken time-reversal symmetry and spin-orbit coupling. We illustrate our idea by performing ab initio calculations for graphene adsorbed on the (111) surface of BiFeO3. In this case, we find that the proximity-induced exchange field in graphene is about 70 meV, and that a topologically nontrivial band gap is opened by Rashba spin-orbit coupling. The size of the gap depends on the separation between the graphene and the thin film substrate, which can be tuned experimentally by applying external pressure.

A new analysis of Mars "Special Regions": findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2)

Abstract: A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of n...

“21st-Century Skills”

Abstract: There is no single set of “21st-Century Skills” and hundreds have been suggested. Many lists include life skills (agility, flexibility, and adaptability), workforce skills (collaboration, leadership initiative, and responsibility), applied skills (accessing and analyzing information, effective communication, and determining alternative solutions to problems), personal skills (curiosity, imagination, critical thinking, and problem solving), interpersonal skills (cooperation and teamwork), and noncognitive skills (managing feelings) (adapted from Saavedra & Opfer, 2012).

Responses of terrestrial aridity to global warming

Abstract: The dryness of terrestrial climate can be measured by the ratio of annual precipitation (P) to potential evapotranspiration (PET), where the latter represents the evaporative demand of the atmosphere, which depends on the surface air temperature, relative humidity, wind speed, and available energy. This study examines how the terrestrial mean aridity responds to global warming in terms of P/PET using the Coupled Model Intercomparison Project phase 5 transient CO2 increase to 2 × CO2 simulations. We show that the (percentage) increase (rate) in P averaged over land is ~1.7%/°C ocean mean surface air temperature increase, while the increase in PET is 5.3%/°C, leading to a decrease in P/PET (i.e., a drier terrestrial climate) by ~3.4%/°C. Noting a similar rate of percentage increase in P over land to that in evaporation (E) over ocean, we propose a framework for examining the change in P/PET, in which we compare the change in PET over land and E over ocean, both expressed using the Penman–Monteith formula. We show that a drier terrestrial climate is caused by (i) enhanced land warming relative to the ocean, (ii) a decrease in relative humidity over land but an increase over ocean, (iii) part of increase in net downward surface radiation going into the deep ocean, and (iv) different responses of PET over land and E over ocean for given changes in atmospheric conditions (largely associated with changes in temperatures). The relative contributions to the change in terrestrial mean aridity from these four factors are about 35%, 35%, 15%, and 15%, respectively. The slight slowdown of the surface wind over both land and ocean has little impact on the terrestrial mean aridity.

Grand challenges for archaeology

Abstract: This article represents a systematic effort to answer the question, What are archaeology’s most important scientific challenges? Starting with a crowd-sourced query directed broadly to the professional community of archaeologists, the authors augmented, prioritized, and refined the responses during a two-day workshop focused specifically on this question. The resulting 25 “grand challenges” focus on dynamic cultural processes and the operation of coupled human and natural systems. We organize these challenges into five topics: (1) emergence, communities, and complexity; (2) resilience, persistence, transformation, and collapse; (3) movement, mobility, and migration; (4) cognition, behavior, and identity; and (5) human-environment interactions. A discussion and a brief list of references accompany each question. An important goal in identifying these challenges is to inform decisions on infrastructure investments for archaeology. Our premise is that the highest priority investments should enable us to address the most important questions. Addressing many of these challenges will require both sophisticated modeling and large-scale synthetic research that are only now becoming possible. Although new archaeological fieldwork will be essential, the greatest pay off will derive from investments that provide sophisticated research access to the explosion in systematically collected archaeological data that has occurred over the last several decades.

Colloquium: Emergent properties in plane view: Strong correlations at oxide interfaces

Abstract: Finding new collective electronic states in materials is one of the fundamental goals of condensed matter physics. Atomic-scale superlattices formed from transition metal oxides are a particularly appealing hunting ground for new physics. In bulk form, transition metal oxides exhibit a remarkable range of magnetic, superconducting, and multiferroic phases that are of great scientific interest and are potentially capable of providing innovative energy, security, electronics, and medical technology platforms. In superlattices new states may emerge at the interfaces where dissimilar materials meet. This Colloquium illustrates the essential features that make transition metal oxide-based heterostructures an appealing discovery platform for emergent properties with a few selected examples, showing how charge redistributes, magnetism and orbital polarization arises, and ferroelectric order emerges from heterostructures comprised of oxide components with nominally contradictory behavior with the aim providing insight into the creation and control of novel behavior at oxide interfaces by suitable mechanical, electrical, or optical boundary conditions and excitations.

Innovative Data Collection Strategies in Qualitative Research

Abstract: Introduction In many disciplines and fields representing the social and behavioral sciences, the quantitative research paradigm, which has its roots in (logical) positivism, marked the first methodological wave (circa the 19th century), inasmuch as it was characterized by a comprehensive and formal set of assumptions and principles surrounding epistemology (e.g., independence of knower and known, objectivism, real causes determining outcomes reliably and validly, time- and context-free generalizations), ontology (e.g., single reality), axiology (e.g., value-free), methodology (e.g., deductive logic, testing or confirming hypotheses/theory), and rhetoric (e.g., rhetorical neutrality, formal writing style, impersonal passive voice, technical terminology). The years 1900 to 1950 marked what could be termed as the second methodological wave, in which many researchers who rejected (logical) positivism embraced the qualitative research paradigm (1). Denzin and Lincoln (2005a) refer to this era as the first historical moment or The Traditional Period for qualitative research. Vidich and Lyman (2000) describe earlier forms of ethnography that took place prior to the 17th century. However, Denzin and Lincoln's (2005a) The Traditional Period represents the first organized qualitative research movement. Although this moment was characterized by qualitative researchers attempting to write reliable, valid, and objective accounts of their field experiences (Denzin & Lincoln, 2005a), it paved the way for the eight subsequent qualitative moments (see Table 1) that have incorporated paradigms that are extremely far removed from positivism. For example, in stark contrast to positivism, constructivism has been characterized by a different set of epistemological (e.g., subjectivist, knower and known are inseparable), ontological (e.g., relativism), axiological (e.g., value-bound), methodological (e.g., dialectical, hermeneutical), and rhetorical (e.g., informal writing style using personal voice and limited definitions) assumptions. From Table 1, it can be seen that Denzin and Lincoln (2005a) predict that in the seventh and eighth moments, "methodological contestation will continue within and among the many disciplinary communities of qualitative research--business, marketing, nursing, psychology, communications studies, cultural studies, education, sociology, anthropology, medical clinical practice and epidemiology, and others" (p. 1117). As noted on Table 1, Denzin and Lincoln (2005a) elaborate further upon the dichotomous nature of research by predicting that in the ninth moment, methodologists form two opposing camps (i.e., "gold standard" of scientific research vs. socially, culturally, ethnically, and racially responsive, communitarian, justice-oriented research). However, in this article, we discuss the various ways that qualitative researchers might transcend this methodological contestation and methodological divide by taking advantage of the innovative approaches to reflexivity (i.e., "the process of critical self-reflection on one's biases, theoretical predispositions, preferences, and so forth" [Schwandt, 2007, p. 260]; "inspection of potential sources of bias and their control [and] critically inspecting the entire research process" [Schwandt, p. 260]); and the latest technology and computermediated communication. As such, we call for a 10th moment, which we label as the period of Methodological Innovation, in which qualitative researchers go beyond the traditional ways of collecting primary and reflexive data. With this in mind, in this article, we provide an innovative meta-framework comprising strategies designed to guide qualitative data collection in the 21st century. We call our framework a meta-framework because it incorporates several new and existing frameworks. We begin by presenting various frameworks for collecting data in qualitative research. Specifically, we present strategies for collecting data from interviews, focus groups, observations, and documents/material culture--which represent four major sources of data in qualitative research (cf. …

Gender Differences in Heterosexual College Students' Conceptualizations and Indicators of Sexual Consent: Implications for Contemporary Sexual Assault Prevention Education

Abstract: Because sexual assault is often defined in terms of nonconsent, many prevention efforts focus on promoting the clear communication of consent as a mechanism to reduce assault. Yet little research has specifically examined how sexual consent is being conceptualized by heterosexual college students. In this study, 185 Midwestern U.S. college students provided responses to open-ended questions addressing how they define, communicate, and interpret sexual consent and nonconsent. The study aimed to assess how college students define and communicate consent, with particular attention to gender differences in consent. Results indicated no gender differences in defining consent. However, there were significant differences in how men and women indicated their own consent and nonconsent, with women reporting more verbal strategies than men and men reporting more nonverbal strategies than women, and in how they interpreted their partner's consent and nonconsent, with men relying more on nonverbal indicators of consent than women. Such gender differences may help to explain some misunderstandings or misinterpretations of consent or agreement to engage in sexual activity, which could partially contribute to the occurrence of acquaintance rape; thus, a better understanding of consent has important implications for developing sexual assault prevention initiatives.

You Don’t Forget Your Roots: The Influence of CEO Social Class Background on Strategic Risk Taking

Abstract: Social class is increasingly recognized as a powerful force in people’s lives. Yet despite the long and extensive stream of research on the upper echelons of organizations, we know little about how...

Coordinated regulation of photosynthesis in rice increases yield and tolerance to environmental stress

Abstract: Plants capture solar energy and atmospheric carbon dioxide (CO2) through photosynthesis, which is the primary component of crop yield, and needs to be increased considerably to meet the growing global demand for food. Environmental stresses, which are increasing with climate change, adversely affect photosynthetic carbon metabolism (PCM) and limit yield of cereals such as rice (Oryza sativa) that feeds half the world. To study the regulation of photosynthesis, we developed a rice gene regulatory network and identified a transcription factor HYR (HIGHER YIELD RICE) associated with PCM, which on expression in rice enhances photosynthesis under multiple environmental conditions, determining a morpho-physiological programme leading to higher grain yield under normal, drought and high-temperature stress conditions. We show HYR is a master regulator, directly activating photosynthesis genes, cascades of transcription factors and other downstream genes involved in PCM and yield stability under drought and high-temperature environmental stress conditions.

Enterprise system implementation and employee: understanding the role of advice networks

Abstract: The implementation of enterprise systems, such as enterprise resource planning (ERP) systems, alters business processes and associated workflows, and introduces new software applications that employees must use. Employees frequently find such technology-enabled organizational change to be a major challenge. Although many challenges related to such changes have been discussed in prior work, little research has focused on post-implementation job outcomes of employees affected by such change. We draw from social network theory-- specifically, advice networks--to understand a key post-implementation job outcome (i.e., job performance). We conducted a study among 87 employees, with data gathered before and after the implementation of an ERP system module in a business unit of a large organization. We found support for our hypotheses that workflow advice and software advice are associated with job performance. Further, as predicted, we found that the interactions of workflow and software get-advice, workflow and software give-advice, and software get- and give-advice were associated with job performance. This nuanced treatment of advice networks advances our understanding of post-implementation success of enterprise systems.

Wide Bandgap Technologies and Their Implications on Miniaturizing Power Electronic Systems

Abstract: The current state of wide bandgap device technology is reviewed and its impact on power electronic system miniaturization for a wide variety of voltage levels is described. A synopsis of recent complementary technological developments in passives, integrated driver, and protection circuitry and electronic packaging are described, followed by an outline of the applications that stand to be impacted. A glimpse into the future based on the current technological trends is offered.

Understanding e-Government portal use in rural India: role of demographic and personality characteristics

Abstract: Electronic government e-Government is one of the most important ways to bridge the digital divide in developing countries. We develop a model of e-Government portal use. We use various individual characteristics, namely demographics and personality, as predictors of e-Government portal use. Specifically, our predictors were 1 gender, age, income and education; 2 the Big Five personality characteristics, i.e. extraversion, neuroticism, conscientiousness, agreeableness and openness to experience; and 3 personal innovativeness with information technology. We conducted a field study in a village in India. We collected data from over 300 heads of household. We found support for our model, with most variables being significant and explaining 40% of the variance in e-Government portal use.

Grand challenges for archaeology

Abstract: Archaeology is a source of essential data regarding the fundamental nature of human societies. Researchers across the behavioral and social sciences use archeological data in framing foundational arguments. Archaeological evidence frequently undergirds debate on contemporary issues. We propose here to answer “What are archaeology’s most important scientific challenges?” The question arose as we sought to develop recommendations for investments in computational infrastructure that would enable the discipline to address its most compelling questions. Absent a list of these questions, we undertook to develop our own.

Direct-bandgap GeSn grown on silicon with 2230 nm photoluminescence

Abstract: Material and optical characterizations have been conducted for epitaxially grown Ge1−xSnx thin films on Si with Sn composition up to 10%. A direct bandgap Ge0.9Sn0.1 alloy has been identified by temperature-dependent photoluminescence (PL) study based on the single peak spectrum and the narrow line-width. Room temperature PL emission as long as 2230 nm has also been observed from the same sample.

The Current State of Business Intelligence in Academia: The Arrival of Big Data

Abstract: In December 2012, the AIS Special Interest Group on Decision Support, Knowledge and Data Management Systems (SIGDSS) and the Teradata University Network (TUN) cosponsored the Business Intelligence Congress 3 and conducted surveys to assess academia’s response to the growing market need for students with Business Intelligence (BI) and Business Analytics (BA) skill sets. This panel report describes the key findings and best practices that were identified, with an emphasis on what has changed since the BI Congress efforts in 2009 and 2010. The article also serves as a “call to action” for universities regarding the need to respond to emerging market needs in BI/BA, including “Big Data.” The IS field continues to be well positioned to be the leader in creating the next generation BI/BA workforce. To do so, we believe that IS leaders need to continuously refine BI/BA curriculum to keep pace with the turbulent BI/BA marketplace.

Does the Voluntary Adoption of Corporate Governance Mechanisms Improve Environmental Risk Disclosures? Evidence from Greenhouse Gas Emission Accounting

Abstract: Prior research suggests that voluntary environmental governance mechanisms operate to enhance a firm’s environmental legitimacy as opposed to being a driver of proactive environmental performance activities To understand how these mechanisms contribute to the firm’s environmental legitimacy, we investigate whether environmental corporate governance characteristics are associated with voluntary environmental disclosure We examine an increasingly important attribute of a firm’s disclosure setting, namely the disclosure of greenhouse gas (GHG) information GHG information represents proprietary non-financial information about the firm’s exposure to environmental concerns and is related to the firm’s operations and future profitability Thus, we expect governance participants would view such information as a potentially important strategic device for managing stakeholders’ demands for information concerning environmental risks We find that the presence of an environmental committee and a Chief Sustainability Officer (CSO) is positively associated with the likelihood of GHG disclosure and that CSOs are associated with disclosure transparency Further analysis reveals that the likelihood of disclosure is associated with committee size, number of committee meetings, expertise of committee members and CSO, and overlap between the environmental committee and audit committee Only expertise of the environmental committee members and the CSO are associated with GHG disclosure transparency, while larger committees tend to be associated with lower transparency Our results are particularly important to those with interests in evaluating the potential role that corporate governance mechanisms play in responding to stakeholder concerns about environmental risks Directors and officers who are considering appointment to similar governance positions, may wish to consider what attributes would make such governance positions more influential

Sustainable phosphorus management and the need for a long-term perspective: The legacy hypothesis

Abstract: Perspective: The Legacy Hypothesis Philip M. Haygarth,*,† Helen P. Jarvie,‡ Steve M. Powers, Andrew N. Sharpley, James J. Elser, Jianbo Shen, Heidi M. Peterson, Neng-Iong Chan, Nicholas J. K. Howden, Tim Burt, Fred Worrall, Fusuo Zhang, and Xuejun Liu †Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, U.K. ‡Centre for Ecology and Hydrology, OX10 8BB, Wallingford, Oxfordshire, U.K. University of Notre Dame, Environmental Change Initiative, South Bend, Indiana 46617, United States Division of Agriculture, University of Arkansas, Fayetteville, Arkansas 72701, United States School of Life Sciences, Arizona State University, Tempe, Arizona 85287, United States Center for Resources, Environment and Food Security, China Agricultural University, Key Laboratory of Plant-Soil Interactions, Ministry of Education, Beijing 100193, P. R. China Minnesota Department of Agriculture, Pesticides and Fertilizer Management Division, Saint Paul, Minnesota 55155, United States University of Bristol, Queen’s School of Engineering, BS8 1TH, Bristol, U.K. Durham University, Department of Geography, DH1 3LE, Durham, U.K. Durham University, Department of Earth Sciences, DH1 3LE, Durham, U.K.