Showing papers by "University of Arkansas published in 2016"

Pure and stable metallic phase molybdenum disulfide nanosheets for hydrogen evolution reaction

Abstract: Metallic molybdenum disulfide is a metastable phase of the material. Here, the authors synthesize two-dimensional metallic molybdenum disulfide nanosheets, stabilized by adsorbed aqueous monolayers, and evaluate their catalytic hydrogen evolution activity.

Propensity Score Matching in Accounting Research

Abstract: Propensity score matching (PSM) has become a popular technique for estimating average treatment effects (ATEs) in accounting research. In this study, we discuss the usefulness and limitations of PSM relative to more traditional multiple regression (MR) analysis. We discuss several PSM design choices and review the use of PSM in 86 articles in leading accounting journals from 2008-2014. We document a significant increase in the use of PSM from 0 studies in 2008 to 26 studies in 2014. However, studies often oversell the capabilities of PSM, fail to disclose important design choices, and/or implement PSM in a theoretically inconsistent manner. We then empirically illustrate complications associated with PSM in three accounting research settings. We first demonstrate that when the treatment is not binary, PSM tends to confine analyses to a subsample of observations where the effect size is likely to be smallest. We also show that seemingly innocuous design choices greatly influence sample composition and estimates of the ATE. We conclude with suggestions for future research considering the use of matching methods.

Plant adaptation to drought stress.

Abstract: Plants in their natural habitats adapt to drought stress in the environment through a variety of mechanisms, ranging from transient responses to low soil moisture to major survival mechanisms of escape by early flowering in absence of seasonal rainfall. However, crop plants selected by humans to yield products such as grain, vegetable, or fruit in favorable environments with high inputs of water and fertilizer are expected to yield an economic product in response to inputs. Crop plants selected for their economic yield need to survive drought stress through mechanisms that maintain crop yield. Studies on model plants for their survival under stress do not, therefore, always translate to yield of crop plants under stress, and different aspects of drought stress response need to be emphasized. The crop plant model rice ( Oryza sativa) is used here as an example to highlight mechanisms and genes for adaptation of crop plants to drought stress.

Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers.

Abstract: Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 106 GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm–1) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.

The chandra deep field-south survey: 7 ms source catalogs

Abstract: We present X-ray source catalogs for the ≈7 Ms exposure of the Chandra Deep Field-South (CDF-S), which covers a total area of 484.2 arcmin2. Utilizing wavdetect for initial source detection and ACIS Extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three X-ray bands: 0.5-7.0 keV, 0.5-2.0 keV, and 2-7 keV. A supplementary source catalog is also provided, including 47 lower-significance sources that have bright (Ks ≤ 23) near-infrared counterparts. We identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. Based on the X-ray and multiwavelength properties, we identify 711 active galactic nuclei (AGNs) from the main-catalog sources. Compared to the previous ≈4 Ms CDF-S catalogs, 291 of the main-catalog sources are new detections. We have achieved unprecedented X-ray sensitivity with average flux limits over the central ≈1 arcmin2 region of ≈1.9 ×10-17, 6.4 ×10-18, and 2.7 ×10-17 erg cm-2 s-1 in the three X-ray bands, respectively. We provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the X-ray source population at the faintest 0.5-2.0 keV flux levels. The highest X-ray source density reaches ≈50,500 deg-2, and 47% ± 4% of these sources are AGNs (≈23,900 deg-2). (Less)

Waste to energy potential: A case study of Saudi Arabia

Abstract: This paper reviews the global status of waste to energy (WTE) technologies as a mean for renewable energy production and municipal solid waste (MSW) disposal method. A case study of the Kingdom of Saudi Arabia (KSA) under this concept was developed. The WTE opportunities in the KSA is undertaken in the context of two scenarios: (1) incineration and (2) refuse derived fuel (RDF) along with biomethanation from 2012 to 2035. Biomethanation technology can proved to be the most suitable WTE technology for KSA due to (a) availability of high food waste volume (37% of total MSW) that can be used as a feedstock, (b) higher efficiency (25–30%) and (c) lowest annual capital ($0.1–0.14/ton) and operational cost. However, the need for large space for continuous operation might increase operational cost. The RDF has an advantage over incineration due to (a) less annual capital ($7.5–11.3/ton) and (b) operational cost ($0.3–0.55/ton), but the high labor skills requirements will most probably be a limitation, if appropriate training and related infrastructure are not scheduled to be included as a prerequisite. The incineration technology also proves to be an efficient solution with a relatively higher efficiency (25%) and lower operational cost ($1.5–2.5/ton). However, the need for treatment of air and waterborne pollutants and ash within the incineration facility can be the limiting factors for the development of this technology in KSA. In 2012, the power generation potential for KSA was estimated at 671 MW and 319.4 MW from incineration and RDF with biomethanation scenarios respectively, which was forecasted to reach upto 1447 MW and 699.76 MW for both scenarios respectively by 2035. Therefore, WTE technologies, could make a substantial contribution to the renewable energy production in KSA as well as alleviating the cost of landfilling and its associated environmental impacts. However, the decision to select between the two scenarios requires further in-depth financial, technical and environmental analysis using life cycle assessment (LCA) tool.

Guidelines for Conducting Mixed-methods Research: An Extension and Illustration

Abstract: The objective of this paper is to extend the guidelines of Venkatesh et al. (2013) for mixed methods research by identifying and integrating variations in mixed methods research. By taking into account 14 properties of mixed methods research (e.g., purposes, research questions, epistemological assumptions), our guidelines demonstrate how researchers can flexibly identify the existing variations in mixed methods research and proceed accordingly with a study design that suits their needs. To make the guidelines actionable for various situations and issues that researchers could encounter, we develop a decision tree to map the flow and relationship among the design strategies. We also provide an in-depth illustration of one possible type of mixed methods research in information systems and discuss how to develop and validate meta-inferences as the outcomes of such a study.

Reducing Implicit Racial Preferences: II. Intervention Effectiveness Across Time

Abstract: Implicit preferences are malleable, but does that change last? We tested 9 interventions (8 real and 1 sham) to reduce implicit racial preferences over time. In 2 studies with a total of 6,321 participants, all 9 interventions immediately reduced implicit preferences. However, none were effective after a delay of several hours to several days. We also found that these interventions did not change explicit racial preferences and were not reliably moderated by motivations to respond without prejudice. Short-term malleability in implicit preferences does not necessarily lead to long-term change, raising new questions about the flexibility and stability of implicit preferences. (PsycINFO Database Record

The Complexities of Sexual Consent Among College Students: A Conceptual and Empirical Review

Abstract: Headlines publicize controversies about sexual assault among college students, and universities face pressure to revise their sexual consent policies. What can the social science literature contribute to this discussion? In this article, we briefly discuss reasons for the recent upsurge in attention to these issues, the prevalence of sexual assault among college students, and aspects of college life that increase the risk of sexual assault and complicate sexual consent. We then review the conceptual challenges of defining sexual consent and the empirical research on how young people navigate sexual consent in their daily lives, focusing primarily on studies of U.S. and Canadian students. Integrating these conceptual issues and research findings, we discuss implications for consent policies, and we present five principles that could be useful for thinking about consent. Finally, we discuss some of the limitations of the existing research and suggest directions for future research.

Observation of Parity-Time Symmetry in Optically Induced Atomic Lattices

Abstract: We experimentally demonstrate PT-symmetric optical lattices with periodical gain and loss profiles in a coherently prepared four-level N-type atomic system. By appropriately tuning the pertinent atomic parameters, the onset of PT-symmetry breaking is observed through measuring an abrupt phase-shift jump between adjacent gain and loss waveguides. The experimental realization of such a readily reconfigurable and effectively controllable PT-symmetric waveguide array structure sets a new stage for further exploiting and better understanding the peculiar physical properties of these non-Hermitian systems in atomic settings.

Reducing Implicit Racial Preferences: II. Intervention Effectiveness Across Time

Abstract: Implicit prejudice is malleable, but does that change last? We tested nine interventions (eight real and one sham) that have been demonstrated to reduce implicit racial prejudice temporarily to determine whether their effects also persisted over time. In two studies with a total of 6,321 participants, all nine interventions immediately reduced implicit prejudice, but none were effective after a delay of several hours to several days. We also found that these interventions did not change explicit racial prejudice and were not reliably moderated by motivations to respond without prejudice. Short-term malleability in implicit prejudice does not necessarily lead to longterm change, raising new questions about the flexibility and stability of implicit attitudes.

Electronic and optical properties of strained graphene and other strained 2D materials: a review

Abstract: This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrodinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

Co-creation and higher order customer engagement in hospitality and tourism services: A critical review

Abstract: Purpose – This paper aims to present a review of the literature associated with co-creation and higher-order customer engagement concepts and poses critical questions related to the current state of research. Additionally, the paper presents a framework for customer engagement and co-creation with relevance to hospitality transactions. Design/methodology/approach – Earlier research on co-production, co-creation, consumer engagement and service-dominant logic are discussed and synthesized. Based on this synthesis, links and contrasts of these varying research streams are presented providing an articulation of key characteristics of each and how these might be applied within a hospitality context. Findings – Modalities in service transactions vary among traditional production, co-production and co-creation based on changes in attitudes, enabling technologies and the logic or ideology supporting the change. Transaction characteristics vary among manufacturing, quasi-manufacturing and services based on severa...

Long-term accumulation and transport of anthropogenic phosphorus in three river basins

Abstract: Global food production depends on phosphorus. Phosphorus is broadly applied as fertilizer, but excess phosphorus contributes to eutrophication of surface water bodies and coastal ecosystems1. Here we present an analysis of phosphorus fluxes in three large river basins, including published data on fertilizer, harvested crops, sewage, food waste and river fluxes2, 3, 4. Our analyses reveal that the magnitude of phosphorus accumulation has varied greatly over the past 30–70 years in mixed agricultural–urban landscapes of the Thames Basin, UK, the Yangtze Basin, China, and the rural Maumee Basin, USA. Fluxes of phosphorus in fertilizer, harvested crops, food waste and sewage dominate over the river fluxes. Since the late 1990s, net exports from the Thames and Maumee Basins have exceeded inputs, suggesting net mobilization of the phosphorus pool accumulated in earlier decades. In contrast, the Yangtze Basin has consistently accumulated phosphorus since 1980. Infrastructure modifications such as sewage treatment and dams may explain more recent declines in total phosphorus fluxes from the Thames and Yangtze Rivers3, 4. We conclude that human-dominated river basins may undergo a prolonged but finite accumulation phase when phosphorus inputs exceed agricultural demand, and this accumulated phosphorus may continue to mobilize long after inputs decline.

A Survey on High Mobility Wireless Communications: Challenges, Opportunities and Solutions

Abstract: Providing reliable broadband wireless communications in high mobility environments, such as high-speed railway systems, remains one of the main challenges faced by the development of the next generation wireless systems. This paper provides a systematic review of high mobility communications. We first summarize a list of key challenges and opportunities in high mobility communication systems, then provide comprehensive reviews of techniques that can address these challenges and utilize the unique opportunities. The review covers a wide spectrum of communication operations, including the accurate modeling of high mobility channels, the transceiver structures that can exploit the properties of high mobility environments, the signal processing techniques that can harvest the benefits (e.g., Doppler diversity) and mitigate the impairments (e.g., carrier frequency offset, intercarrier interference, channel estimation errors) in high mobility systems, and the mobility management and network architectures that are designed specifically for high mobility systems. The survey focuses primarily on physical layer operations, which are affected the most by the mobile environment, with some additional discussions on higher layer operations, such as handover management and control-plane/user-plane decoupling, which are essential to high mobility operations. Future research directions on high mobility communications are summarized at the end of this paper.

Managing Citizens’ Uncertainty in E-Government Services: The Mediating and Moderating Roles of Transparency and Trust

Abstract: This paper investigates how citizens’ uncertainty in e-government services can be managed. First, we draw from uncertainty reduction theory, and propose that transparency and trust are two key means of reducing citizens’ uncertainty in e-government services. Second, we identify two key sets of relevant drivers of e-government service use: (1) information quality characteristics, i.e., accuracy and completeness; and (2) channel characteristics, i.e., convenience and personalization. We propose that the means of uncertainty reduction, information quality characteristics, and channel characteristics are interrelated factors that jointly influence citizens’ intentions to use e-government. We tested our model with 4,430 Hong Kong citizens’ reactions to two e-government services: government websites and online appointment booking. Our results show that the information quality and channel characteristics predict citizens’ intentions to use e-government. Furthermore, transparency and trust mediate as well as mode...

Probing Carrier Transport and Structure-Property Relationship of Highly Ordered Organic Semiconductors at the Two-Dimensional Limit.

Abstract: One of the basic assumptions in organic field-effect transistors, the most fundamental device unit in organic electronics, is that charge transport occurs two dimensionally in the first few molecular layers near the dielectric interface. Although the mobility of bulk organic semiconductors has increased dramatically, direct probing of intrinsic charge transport in the two-dimensional limit has not been possible due to excessive disorders and traps in ultrathin organic thin films. Here, highly ordered single-crystalline mono- to tetralayer pentacene crystals are realized by van der Waals (vdW) epitaxy on hexagonal BN. We find that the charge transport is dominated by hopping in the first conductive layer, but transforms to bandlike in subsequent layers. Such an abrupt phase transition is attributed to strong modulation of the molecular packing by interfacial vdW interactions, as corroborated by quantitative structural characterization and density functional theory calculations. The structural modulation becomes negligible beyond the second conductive layer, leading to a mobility saturation thickness of only ∼3 nm. Highly ordered organic ultrathin films provide a platform for new physics and device structures (such as heterostructures and quantum wells) that are not possible in conventional bulk crystals.

Pornography and the Male Sexual Script: An Analysis of Consumption and Sexual Relations

Abstract: Pornography has become a primary source of sexual education. At the same time, mainstream commercial pornography has coalesced around a relatively homogenous script involving violence and female degradation. Yet, little work has been done exploring the associations between pornography and dyadic sexual encounters: What role does pornography play inside real-world sexual encounters between a man and a woman? Cognitive script theory argues media scripts create a readily accessible heuristic model for decision-making. The more a user watches a particular media script, the more embedded those codes of behavior become in their worldview and the more likely they are to use those scripts to act upon real life experiences. We argue pornography creates a sexual script that then guides sexual experiences. To test this, we surveyed 487 college men (ages 18-29 years) in the United States to compare their rate of pornography use with sexual preferences and concerns. Results showed the more pornography a man watches, the more likely he was to use it during sex, request particular pornographic sex acts of his partner, deliberately conjure images of pornography during sex to maintain arousal, and have concerns over his own sexual performance and body image. Further, higher pornography use was negatively associated with enjoying sexually intimate behaviors with a partner. We conclude that pornography provides a powerful heuristic model which is implicated in men's expectations and behaviors during sexual encounters.

Physics of Ultrathin Films and Heterostructures of Rare-Earth Nickelates

Abstract: The electronic structure of transition metal oxides featuring correlated electrons can be rationalized within the Zaanen-Sawatzky-Allen framework. Following a brief description of the present paradigms of electronic behavior, we focus on the physics of rare-earth nickelates as an archetype of complexity emerging within the charge transfer regime. The intriguing prospect of realizing the physics of high-Tc cuprates through heterostructuring resulted in a massive endeavor to epitaxially stabilize these materials in ultrathin form. A plethora of new phenomena unfolded in such artificial structures due to the effect of epitaxial strain, quantum confinement, and interfacial charge transfer. Here we review the present status of artificial rare-earth nickelates in an effort to uncover the interconnection between the electronic and magnetic behavior and the underlying crystal structure. We conclude by discussing future directions to disentangle the puzzle regarding the origin of the metal-insulator transition, th...

Plant abiotic stress challenges from the changing environment

Abstract: The challenges of abiotic stress on plant growth and development are evident among the emerging ecological impacts of climate change (Bellard et al., 2012), and the constraints to crop production exacerbated with the increasing human population competing for environmental resources (Wallace et al., 2003). Climate change is predicted to affect agricultural production the most, primarily at low latitudes populated by developing countries, with adverse effects of increasing carbon dioxide and high temperature, challenging researchers toward devising adaptation strategies (Rosenzweig et al., 2014). These constraints to global food supply and a balanced environment encourage research and development of climate smart crops, resilient to climate change (Wheeler and Von Braun, 2013). The field of plant abiotic stress encompasses all studies on abiotic factors or stressors from the environment that can impose stress on a variety of species (Sulmon et al., 2015). These stressors include extreme levels of light (high and low), radiation (UV-B and UV-A), temperature [high and low (chilling, freezing)], water (drought, flooding, and submergence), chemical factors (heavy metals and pH), salinity due to excessive Na+, deficient or in excess of essential nutrients, gaseous pollutants (ozone, sulfur dioxide), mechanical factors, and other less frequently occurring stressors. Since combinations of these stresses such as heat and drought frequently occur under field conditions, and can cause unique effects that cannot be predicted from individual stressors (Suzuki et al., 2014), a multiplicity of physiological interactions can be expected, needing individual novel solutions. Plants are rooted in the environment they grow in, and have to adapt to the changing conditions brought about by the multitude of environmental factors, with extreme levels eliciting abiotic stress. A grand challenge in abiotic stress biology is to decipher how plants perceive the different stressors, how the early signals are transduced within the plant, what is the diversity of response pathways elicited by them, and how are they genetically determined (Yoshida et al., 2014). Beyond model plants and reference genotypes, the challenge is to identify how signaling pathways have evolved within a species to program a suite of responses differing in signals and regulatory networks, and constitute genotypes that are adapted to specific stressful environments. Many studies have begun to deal with the comparison of a few genotypes, such as tolerant and sensitive within a species, for the analysis of differential responses to a defined stress. Since these responses can be due to differences in sets of genes, an understanding of the diversity in signaling pathways can come only by making a systems level study of the differences between genotypes. Such comparative studies offer a challenge for the integration of diverse functional genomics datasets of gene expression, metabolomics, and stress physiological responses to make comparisons in the network of responses across genotypes. A compatible environment for one plant genotype may not be for another, and all external factors abiotic or biotic, can raise a challenge or stress to the plant depending on the plants genetic constitution and adaptive response. The specific genotype × environment interaction combinations offer multitude of effects in response to the environment (Des Marais et al., 2013). Molecular genetic analysis of specific genes conferring stress tolerance from tolerant crop accessions have resulted in the map-based isolation of genes for submergence tolerance (Xu et al., 2006) and salt tolerance (Ren et al., 2005) in rice, among many others. The challenge ahead is in the analysis of natural variation in populations using genome wide association studies (GWAS) to dissect quantitative traits from field screens of diverse genotypes and map specific naturally occurring “stress tolerant loci.” This has been successful for salt tolerance (Kumar et al., 2015) in rice, and also led to the identification from maize of the first drought tolerance gene (Mao et al., 2015). The variation within the maize drought tolerance gene is particularly interesting because the drought sensitive allele contains a transposon insert in the promoter that is involved in epigenetic regulation of the gene that differs in distribution between temperate and tropical maize. Transposons as agents of regulation of genes in abiotic stress are being identified in maize as “controlling elements” involved in the regulation of around 20% of the abiotic stress responsive genes (Makarevitch et al., 2015), indicating evolution and selection of novel stress protective alleles active in natural populations. Similarly in rice, insertions of the mPing transposon with insertion preference in the 5′ regions of genes were shown to up-regulate the downstream genes and render them stress responsive (Naito et al., 2009). The intriguing challenge ahead is to now see how far McClintock's controlling elements (McClintock, 1984), that are induced to move under stress can help plants survive abiotic stresses by creating and regulating networks of genes for stress protection. The new challenges will come from genome-wide analyses of stress tolerant genotypes from multiple plant species that will probably reveal novel tolerance and selective mechanisms in natural populations. The supporting technologies from next-generation sequencing to GWAS are available in many plant species, and much research is concentrated in this area for stress tolerance. This is therefore an area for future discoveries that will reveal the evolution of diverse mechanisms for stress tolerance that could be valuable for the design of crop improvement strategies including for climate change challenges. A fruitful strategy for the identification of stress tolerance genes has been by reverse genetics analyses of candidate genes identified through gene expression studies and other bioinformatics methods. The biological role of such candidate genes has been most often tested by the analysis of overexpression, knockout/knockdown genotypes in model, and crop plants (Todaka et al., 2015). Overexpression studies with transcription factors and other regulatory genes have been popular in transgenic crops, with the objective of improving their stress tolerance and productivity (Mickelbart et al., 2015), and often enabling applications across plant species. The potential redundancy of stress tolerance genes remains a challenge, since overexpression studies might not represent the natural function of genes in the plant. Nevertheless, all studies testing the potential phenotype of genes for alterations in stress response provide useful information on the gene function as well as the applications. Gene expression analysis of plants in response to abiotic stresses reveals a large fraction of the genome can be perturbed, reflecting the plasticity in stress response and protection. The complexity of a plants' response to abiotic stress factors, in interaction with its genetic constitution, provides a multitude of morpho-physiological, biochemical, gene expression, and other molecular responses that can best be described by networks of response pathways leading to expression of tolerance and adaptation to the environment. The role of genetics and evolution propounded by Darwinism seemed to prevail over the opposing views of Lamarckism, proposing life forms could acquire information from their environment and pass it on in their genes. Now, two centuries later the evidence from epigenetics is showing us in surprising detail, with the sophistication of genomics technologies, how the epigenome carries information that is not encoded in the DNA to offspring, and can even provide a mechanism for acclimation and adaptation to stress (Avramova, 2015). The role of the environment, and subsequently stresses that might permanently plague plants, probably have a significant epigenetic influence on the behavior of plants and their progeny, and provide new challenges to re-visit plant–environment interactions. Abiotic stresses will remain a challenge to the natural environment and agriculture. The early evolution of land plants took place under dry conditions with extremes of temperature and harsh sunlight, while crop domestication occurred later in more favorable environments. Subsequently, the selection of plants for productivity traits did not always result in crops that are productive under random stress factors, although the natural variation of crops are genetic reservoirs for abiotic stress adaptation. Presently, with the competing uses of land and the growing world population we are challenged to produce more in less area with dwindling resources of water, confronted with climate change increases in temperature and carbon dioxide, and the unpredictable local microclimate adversely affecting crop productivity. The challenges before us in plant biology and crop improvement are to integrate the systems level information on abiotic stress response pathways, identify stress protective networks, and engineer environmentally stable crops that yield more, with less water and dwindling natural resources, to feed the growing world population.

Differential privacy preservation for deep auto-encoders: an application of human behavior prediction

Abstract: In recent years, deep learning has spread beyond both academia and industry with many exciting real-world applications. The development of deep learning has presented obvious privacy issues. However, there has been lack of scientific study about privacy preservation in deep learning. In this paper, we concentrate on the auto-encoder, a fundamental component in deep learning, and propose the deep private auto-encoder (dPA). Our main idea is to enforce e-differential privacy by perturbing the objective functions of the traditional deep auto-encoder, rather than its results. We apply the dPA to human behavior prediction in a health social network. Theoretical analysis and thorough experimental evaluations show that the dPA is highly effective and efficient, and it significantly outperforms existing solutions.

Going with the Flow: Predicting Online Purchase Intentions

Abstract: A theoretical model that combines flow theory with the Theory of Reasoned Action is proposed and empirically tested. Data was gathered via a sample survey, which was completed by 342 undergraduate college students. Two-phase structural equation modeling was utilized to verify construct validity and test proposed relationships. The study establishes the psychological state of flow as an important independent variable influencing both Web exploratory behavior and attitude toward purchasing online. In turn, attitude toward purchasing online was found to influence behavioral intentions to engage in online purchase transactions. Exploratory behavior was also identified as an independent variable exerting a significant effect on online purchasing attitude. The resultant model explains 60% of individuals' intentions to make purchases online. Key theoretical and managerial implications are discussed.

Integrating legacy soil phosphorus into sustainable nutrient management strategies for future food, bioenergy and water security

Abstract: Legacy phosphorus (P) that has accumulated in soils from past inputs of fertilizers and manures is a large secondary global source of P that could substitute manufactured fertilizers, help preserve critical reserves of finite phosphate rock to ensure future food and bioenergy supply, and gradually improve water quality. We explore the issues and management options to better utilize legacy soil P and conclude that it represents a valuable and largely accessible P resource. The future value and period over which legacy soil P can be accessed depends on the amount present and its distribution, its availability to crops and rates of drawdown determined by the cropping system. Full exploitation of legacy P requires a transition to a more holistic system approach to nutrient management based on technological advances in precision farming, plant breeding and microbial engineering together with a greater reliance on recovered and recycled P. We propose the term ‘agro-engineering’ to encompass this integrated approach. Smaller targeted applications of fertilizer P may still be needed to optimize crop yields where legacy soil P cannot fully meet crop demands. Farm profitability margins, the need to recycle animal manures and the extent of local eutrophication problems will dictate when, where and how quickly legacy P is best exploited. Based on our analysis, we outline the stages and drivers in a transition to the full utilization of legacy soil P as part of more sustainable regional and global nutrient management.

Sex Differences in Reported Concussion Injury Rates and Time Loss From Participation: An Update of the National Collegiate Athletic Association Injury Surveillance Program From 2004-2005 Through 2008-2009.

Abstract: Context: Epidemiologic studies have identified differences in concussion incidence between the sexes. However, few authors to date have updated injury rates (IRs) and time loss between male and fem...