Digital Commons Network^™

Beyond Aztec Castles: Toric Cascades In The Dp3 Quiver, Tri Lai, Gregg Musiker

Department of Mathematics: Faculty Publications

Given one of an infinite class of supersymmetric quiver gauge theories, string theorists can associate a corresponding toric variety (which is a Calabi-Yau 3-fold) as well as an associated combinatorial model known as a brane tiling. In combinatorial language, a brane tiling is a bipartite graph on a torus and its perfect matchings are of interest to both combinatorialists and physicists alike. A cluster algebra may also be associated to such quivers and in this paper we study the generators of this algebra, known as cluster variables, for the quiver associated to the cone over the del Pezzo surface dP …

No Positive Cone In A Free Product Is Regular, Susan Hermiller, Zoran Sunic

Department of Mathematics: Faculty Publications

We show that there exists no left order on the free product of two nontrivial, finitely generated, left-orderable groups such that the corresponding positive cone is represented by a regular language. Since there are orders on free groups of rank at least two with positive cone languages that are context-free (in fact, 1-counter languages), our result provides a bound on the language complexity of positive cones in free products that is the best possible within the Chomsky hierarchy. It also provides a strengthening of a result by Cristobal Rivas which states that the positive cone in a free product of …

What Do Undergraduate Students Know About Scholarly Communication? A Mixed Methods Study, Catherine Fraser Riehle, Merinda Kaye Hensley

University of Nebraska-Lincoln Libraries: Faculty Publications

Amid movements that recognize undergraduate students as knowledge creators, transformative work is being done at the intersection of information literacy and scholarly communication. Absent from the literature so far is research related to students’ perception and understanding of scholarly communication. This paper reports a mixed methods study at two major research universities in the United States, where undergraduate student researchers were surveyed and interviewed about their scholarly communication practices and perceptions. This work informs development of programming at the intersection of scholarly communication and information literacy in general, and for those involved with undergraduate research experiences in particular.

Pulling In Different Directions? Exploring The Relationship Between Vertical Pay Dispersion And High-Performance Work Systems, Jake G. Messersmith, Kyoung Yong Kim, Pankaj C. Patel

Department of Management: Faculty Publications

Vertical pay dispersion (VPD), a hierarchical pay structure used to motivate employees, has traditionally been studied separately from high-performance work systems (HPWSs). As a component of HPWSs, incentive-based compensation schemes focus on employee- or team-level incentives. However, the influence of the simultaneous utilization of VPD and HPWS on performance remains understudied. This study addresses the question of whether these approaches to managing human capital serve as complements or substitutes to one another. VPD and HPWS are argued to substitute for one another with respect to motivation- and skill-enhancing practices. The opposite notion is true in regard to opportunity-enhancing HPWSs, which …

Graphic Novels: A Brief History, Their Use In Business Education, And The Potential For Negotiation Pedagogy, Mallory Wallace

Department of Management: Faculty Publications

Over an extensive history, graphic novels have developed into a legitimate form of fiction and nonfiction for readers and students. Use of graphic novels in classrooms has proven effective in facilitating learning for students, as a conduit for lifelong reading, a tool for increased comprehension and critical literacy, and a stimulus for interest and comprehension. In applying this to teaching negotiation and conflict management, graphic novels may be effective in engaging students and increasing understanding when terms and concepts are confusing or vague, especially in their differences, and can help students understand the process and outcome of negotiation, both objective …

Tornado Warning Response And Perceptions Among Undergraduates In Nebraska, Sabrina T. Jauernic, Matthew S. Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

Few studies show how university students perceive and respond to tornado warnings. Lacking in the literature are investigations of what influences perceptions of tornado risk among this population and how these perceptions may influence actions. Through an online survey of 640 undergraduates enrolled at a large university in Nebraska, significant relationships were found between student demographics, perceptions, and response actions. Tornado mythology relevant to the local city influenced perceptions so that students felt the city was less at risk than surrounding rural land. Confirming risk before sheltering remained popular, with some students choosing to never seek shelter during a warning. …

Effects Of Aspect Ratio On The Mode Couplings Of Thin-Film Bulk Acoustic Wave Resonators, Nian Li, Zhenghua Qian, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We studied mode couplings in thin film bulk acoustic wave resonators of a piezoelectric film on a dielectric layer operating with the fundamental thickness-extensional mode. A system of plate equations derived in our previous paper was used which includes the couplings to the unwanted in-plane extension, flexure, fundamental and second-order thickness shear modes. It was shown that the couplings depend strongly on the plate length/thickness ratio. For a relatively clean operating mode with weak couplings to unwanted modes, a series of discrete values of the plate length/thickness ratio should be avoided and these values were determined in the present paper. …

Micro/Nanostructures Formation By Femtosecond Laser Surface Processing On Amorphous And Polycrystalline Ni60nb40, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Meiyu Wang, Ryan Bell, Michael J. Lucis, Troy P. Anderson, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni₆₀Nb₄₀ with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface …

Biodegradable Elastic Nanofibrous Platforms With Integrated Flexible Heaters For On-Demand Drug Delivery, Ali Tamayol, Alireza Hassani Najafabadi, Pooria Mostafalu, Ali K. Yetisen, Mattia Commotto, Musab Aldhahri, Mohamed Shaaban Abdel-Wahab, Zeynab Izadi Najafabadi, Shahrzad Latifi, Mohsen Akbari, Nasim Annabi, Seok Hyun Yun, Adnan Memic, Mehmet R. Dokmeci, Ali Khademhosseini

Department of Mechanical and Materials Engineering: Faculty Publications

Delivery of drugs with controlled temporal profiles is essential for wound treatment and regenerative medicine applications. For example, bacterial infection is a key challenge in the treatment of chronic and deep wounds. Current treatment strategies are based on systemic administration of high doses of antibiotics, which result in side effects and drug resistance. On-demand delivery of drugs with controlled temporal profile is highly desirable. Here, we have developed thermally controllable, antibiotic-releasing nanofibrous sheets. Poly(glycerol sebacate)- poly(caprolactone) (PGS-PCL) blends were electrospun to form elastic polymeric sheets with fiber diameters ranging from 350 to 1100 nm and substrates with a tensile modulus …

Solution Nuclear Magnetic Resonance Spectroscopy On A Nanostructured Diamond Chip, P. Kehayias, A. Jarmola, N. Mosavian, I. Fescenko, F.M. Benito, A. Laraoui, J. Smits, L. Bougas, D. Budker, A. Neumann, S.R.J. Brueck, V.M. Acosta

Department of Mechanical and Materials Engineering: Faculty Publications

Sensors using nitrogen-vacancy centers in diamond are a promising tool for small-volume nuclear magnetic resonance (NMR) spectroscopy, but the limited sensitivity remains a challenge. Here we show nearly two orders of magnitude improvement in concentration sensitivity over previous nitrogen-vacancy and picoliter NMR studies. We demonstrate NMR spectroscopy of picoliter-volume solutions using a nanostructured diamond chip with dense, high-aspect-ratio nanogratings, enhancing the surface area by 15 times. The nanograting sidewalls are doped with nitrogen-vacancies located a few nanometers from the diamond surface to detect the NMR spectrum of roughly 1 pl of fluid lying within adjacent nanograting grooves. We perform 1H …

Quantification Of Re-Absorption And Re-Emission Processes To Determine Photon Recycling Efficiency In Perovskite Single Crystals, Yanjun Fang, Haotong Wei, Qingfeng Dong, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Photon recycling, that is, iterative self-absorption and re-emission by the photoactive layer itself, has been speculated to contribute to the high open-circuit voltage in several types of high efficiency solar cells. For organic–inorganic halide perovskites that have yielded highly efficient photovoltaic devices, however, it remains unclear whether the photon recycling effect is significant enough to improve solar cell efficiency. Here we quantitatively evaluate the re-absorption and re-emission processes to determine photon recycling efficiency in hybrid perovskite with its single crystals by measuring the ratio of the re-emitted photons to the initially excited photons, which is realized by modulating their polarization …

Flowtaxis Of Osteoblast Migration Under Fluid Shear And The Effect Of Rhoa Kinase Silencing, Brandon D. Riehl, Jeong Soon Lee, Ligyeom Ha, Il Keun Kwon, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

Despite the important role of mechanical signals in bone remodeling, relatively little is known about how fluid shear affects osteoblastic cell migration behavior. Here we demonstrated that MC3T3-E1 osteoblast migration could be activated by physiologically-relevant levels of fluid shear in a shear stress-dependent manner. Interestingly, shear-sensitive osteoblast migration behavior was prominent only during the initial period after the onset of the steady flow (for about 30 min), exhibiting shear stress-dependent migration speed, displacement, arrest coefficient, and motility coefficient. For example, cell speed at 1 min was 0.28, 0.47, 0.51, and 0.84 μm min^-1 for static, 2, 15, and 25 …

High Temperature Near-Field Nanothermomechanical Rectification, Mahmoud Elzouka, Sidy Ndao

Department of Mechanical and Materials Engineering: Faculty Publications

Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus & Jupiter planetary exploration, and heliophysics missions) and earth-based applications requires the development of alternative computing technologies. In the pursuit of alternative technologies, research efforts have looked into developing thermal memory and logic devices that use heat instead of electricity to perform computations. However, most of the proposed technologies operate at room or cryogenic temperatures, due to their dependence on material’s temperature-dependent properties. Here in this research, we show experimentally—for the first time—the use of near-field thermal radiation …

High-Velocity Projectile Impact Induced 9r Phase In Ultrafine-Grained Aluminium, Sichuang Xue, Zhe Fan, Olawale B. Lawal, Ramathasan Thevamaran, Qiang Li, Yue Liu, K. Y. Yu, Jian Wang, Edwin L. Thomas, Haiyan Wang, Xinghang Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

Aluminium typically deforms via full dislocations due to its high stacking fault energy. Twinning in aluminium, although difficult, may occur at low temperature and high strain rate. However, the 9R phase rarely occurs in aluminium simply because of its giant stacking fault energy. Here, by using a laser-induced projectile impact testing technique, we discover a deformation-induced 9R phase with tens of nm in width in ultrafine-grained aluminium with an average grain size of 140 nm, as confirmed by extensive post-impact microscopy analyses. The stability of the 9R phase is related to the existence of sessile Frank loops. Molecular dynamics simulations …

So What Are You Going To Do With That? The Promises And Pitfalls Of Massive Data Sets, Sigrid Anderson Cordell, Melissa Gomis

University of Nebraska-Lincoln Libraries: Faculty Publications

This article takes as its case study the challenge of data sets for text mining, sources that offer tremendous promise for digital humanities (DH) methodology but present specific challenges for humanities scholars. These text sets raise a range of issues: What skills do you train humanists to have? What is the library’s role in enabling and supporting use of those materials? How do you allocate staff? Who oversees sustainability and data management? By addressing these questions through a specific use case scenario, this article shows how these questions are central to mapping out future directions for a range of library …

Wealth Inequality And Activism: Perceiving Injustice Galvanizes Social Change But Perceptions Depend On Political Ideologies, Crystal L. Hoyt, Aaron J. Moss, Jeni L. Burnette, Annette Schieffelin, Abigail Goethals

Jepson School of Leadership Studies articles, book chapters and other publications

What motivates people to engage in activism against wealth inequality? The simple answer is, perceiving injustice. However, the current work demonstrates that these perceptions depend on political ideologies. More specifically, for political liberals who frequently question the fairness of the economic system, messages simply describing the extent of the inequality (distributive injustice) are enough to motivate activism (Study 1). For political conservatives, who are inclined to believe that inequality results from fair procedures, messages must also detail how the system of economic forces is unjust (procedural injustice; Studies 2 and 3). Together, these studies suggest perceiving injustice can galvanize social …

Changing Owners, Changing Content: Does Who Owns The News Matter For The News?, Allison M.N. Archer, Joshua D. Clinton

Jepson School of Leadership Studies articles, book chapters and other publications

The press is essential for creating an informed citizenry, but its existence depends on attracting and maintaining an audience. It is unclear whether supply-side effects – including those dictated by the owners of the media – influence how the media cover politics, yet this question is essential given their abilities to set the agenda and frame issues that are covered. We examine how ownership influences media behavior by investigating the impact of Rupert Murdoch’s purchase of the Wall Street Journal (WSJ) in August 2007. We collect data on every front-page story and editorial for 27 months, and we …

Smart Underground Antenna Arrays: A Soil Moisture Adaptive Beamforming Approach, Abdul Salam, Mehmet C. Vuran

School of Computing: Technical Reports

In this paper, a novel framework for underground beamforming using adaptive antenna arrays is presented. Based on the analysis of propagation in wireless underground channel, a theoretical model is developed which uses soil moisture information and feedback mechanism to improve performance wireless underground communications. Array element in soil has been analyzed empirically and impacts of soil type and soil moisture on return loss and resonant frequency are investigated. Beam patterns are investigated to communicate with both underground and above ground devices. Depending on the incident angle, refraction from soil-air interface has the adverse effects in the UG communications. It is …

Sciencesds: A Novel Software Defined Security Framework For Large-Scale Data-Intensive Science, Deepak Nadig Anantha, Byrav Ramamurthy

School of Computing: Faculty Publications

Experimental science workflows from projects such as Compact Muon Solenoid (CMS) [6] and Laser Interferometer Gravitational Wave Observatory (LIGO) [2] are characterized by data-intensive computational tasks over large datasets transferred over encrypted channels. The Science DMZ [7] approach to network design favors lossless packet forwarding through a separate isolated network over secure lossy forwarding through stateful packet processors (e.g. fire-walls). We propose ScienceSDS, a novel software denied security framework for securely monitoring large-scale science datasets over a software defined networking and network functions virtualization (SDN/NFV) infrastructure.

Communicatively Constructing The Bright And Dark Sides Of Hope: Family Caregivers’ Experiences During End Of Life Cancer Care, Jody Koenig Kellas, Katherine M. Castle, Alexis Johnson, Marlene Z. Cohen

Department of Communication Studies: Faculty Publications

(1) Background: The communication of hope is complicated, particularly for family caregivers in the context of cancer who struggle to maintain hope for themselves and their loved ones in the face of terminality. In order to understand these complexities, the current study examines the bright and dark sides of how hope is communicated across the cancer journey from the vantage point of bereaved family caregivers; (2) Methods: We analyzed interviews with bereaved family caregivers using qualitative thematic and case oriented strategies to identify patterns in the positive and negative lived experiences when communicating about hope at the end of life; …

“Love Needs To Be Exchanged”: A Diary Study Of Interaction And Enactment Of The Family Kinkeeper Role, Dawn O. Braithwaite, Jaclyn S. Marsh, Carol L. Tschampl-Diesing, Margaret S. Leach

Department of Communication Studies: Faculty Publications

Family kinkeepers enact an important role centered on interaction and maintaining family relationships. The researchers studied kinkeeping communication in light of mediated communication, topics engaged, and kinkeepers’ assessments. Thirty-four self-identified kinkeepers kept an interaction diary over 2 weeks. Their 275 reports represented 1,487 interactions using largely mediated communication channels (text, telephone, e-mail, social media), centered on everyday activities, rituals, and health and safety. Despite potential complications of the role, kinkeepers reported high agreement and openness with family members, little conflict, and overall satisfaction with their interactions. Implications of these findings, new directions for researchers, and the important mediated role of …

Perceived Benefits And Challenges Of A Multiethnic-Racial Identity: Insight From Adults With Mixed Heritage, Jordan Soliz, Sierra Cronan, Gretchen Bergquist, Audra K. Nuru, Christine E. Rittenour

Department of Communication Studies: Faculty Publications

The purpose of this inquiry was to explore the lived experiences of multiethnic-racial individuals (i.e., individuals with parents from different ethnic-racial groups). In-depth interviews were conducted with 29 adults from the United States with mixed ethnic-racial backgrounds ranging in age from 18 to 52 (female n = 20, male n = 9). We identified a number of themes related to perceived benefits (e.g., pluralistic world views, stronger sense of self) and challenges (e.g., identity tensions, communal concerns) of having a mixed heritage. Findings are discussed in terms of four considerations for ethnic-racial identity of individuals with mixed ethnic-racial backgrounds: emphasizing …

The Role Of Health Care Provider And Partner Decisional Support In Patients’ Cancer Treatment Decision-Making Satisfaction, Angela L. Palmer-Wackerly, Janice L. Krieger, Nancy D. Rhodes

Department of Communication Studies: Faculty Publications

Cancer patients rely on multiple sources of support when making treatment decisions; however, most research studies examine the influence of health care provider support while the influence of family member support is understudied. The current study fills this gap by examining the influence of health care providers and partners on decision-making satisfaction. In a cross-sectional study via an online Qualtrics panel, we surveyed cancer patients who reported that they had a spouse or romantic partner when making cancer treatment decisions (n = 479). Decisional support was measured using 5-point, single-item scales for emotional support, informational support, informational-advice support, and appraisal …

How Selective Amnesia Brought Us The First Black Socialist President Of The United States, Kristen Hoerl

Department of Communication Studies: Faculty Publications

Post-Racial Amnesia during President Obama’s 2008 Inauguration

My interest in public memory explains why news coverage leading up to President Obama’s inauguration rankled me. The endless news cycle kept repeating trite statements that announced that the civil rights struggle had ended. Reports quoted public officials and former civil rights activists who described Obama’s election as the “fulfillment,” “embodiment,” “culmination,” and “validation” of Martin Luther King Jr.’s dream. The inauguration took place the day after Martin Luther King Day, and Obama delivered a pre-inauguration address in front of the Lincoln Memorial, the same location where King delivered his 1963 speech. Given …

Postmodern/Poststructural Approaches, Jennifer J. Mease (Also Peeksmease)

Department of Communication Studies: Faculty Publications

Postmodern and poststructural approaches to organizational communication are marked by an emphasis on ruptures, disjunctions, tensions, instabilities, and other inconsistencies as a part of everyday organizational life. This emphasis is part of an attempt to question, critique, and often compromise the normalized, mundane power structures that regulate organizational life. By questioning and critiquing, these approaches reveal norms and power structures as contingently constructed with particular interests at play. This contrasts with more traditional assumptions that treat norms and power structures as natural, neutral, and stable constructions.

Poststructural and postmodern approaches to organizational communication find their roots in broader philosophical movements …

Simulation As Supplementary Tool In Construction Management Education, Saeed Rokooei, James D. Goedert, Asregedew Woldesenbet

Department of Construction Engineering and Management: Faculty Publications

Many academic programs utilize simulation applications to supplement higher education, but there are only a few applications responding to the need in construction curricula, particularly with a focus on project management. Project management is an interdisciplinary area of study, crosscutting multiple fields including the construction, information technology, and business sectors. This paper presents the design, development, and test of a research project entitled Project-oriented Educational Research Fostering Excellence in Cyber-infrastructure Teaching (PERFECT). It investigates the effect of a construction project management simulation on construction management students’ engagement and perceptions at the University of Nebraska- Lincoln.

The goal of PERFECT was …

Reply To ‘On The Bonding In Ligand-Protected Gold Clusters’, Wen Wu Xu, Xiao Cheng Zeng, Yi Gao

Xiao Cheng Zeng Publications

In the recent Correspondence, Professor Henrik Grönbeck made several comments on the recently developed grand unified model (GUM), in particular using the ligand-protected gold cluster [Au₂₅(SR)₁₈]¹⁻ as an example. We noted that the latter cluster can be viewed as belonging to a special group of ligand-protected gold clusters that contain one or several icosahedral Au₁₃ motifs. For this group of clusters, a secondary block Au₁₃(8e) has been identified as a more convenient way to describe their structure anatomy and evolution. Another extension of the GUM is the identification of the new elementary …

Young Children With Down Syndrome Show Normal Development Of Circadian Rhythms, But Poor Sleep Efficiency: A Cross-Sectional Study Across The First 60 Months Of Life, Fabian Fernandez, Casandra C. Nyhuis, Payal Anand, Bianca I. Demara, Norman F. Ruby, Goffredina Spano, Caron Clark, Jamie O. Edgin

Department of Educational Psychology: Faculty Publications

Objectives: To evaluate sleep consolidation and circadian activity rhythms in infants and toddlers with Down syndrome (DS) under light and socially entrained conditions within a familiar setting. Given previous human and animal data suggesting intact circadian regulation of melatonin across the day and night, it was hypothesized that behavioral indices of circadian rhythmicity would likewise be intact in the sample with DS.

Methods: A cross-sectional study of 66 infants and young children with DS, aged 5e67 months, and 43 typically developing age-matched controls. Sleep and measures of circadian robustness or timing were quantified using continuous in-home actigraphy recordings performed over …

Wireless Underground Channel Diversity Reception With Multiple Antennas For Internet Of Underground Things, Abdul Salam, Mehmet C. Vuran

School of Computing: Conference and Workshop Papers

Internet of underground things (IOUT) is an emerging paradigm which consists of sensors and communication devices, partly or completely buried underground for real-time soil sensing and monitoring. In this paper, the performance of different modulation schemes in IOUT communications is studied through simulations and experiments. The spatial modularity of direct, lateral, and reflected components of the UG channel is exploited by using multiple antennas. First, it has been shown that bit error rates of $10^{-3}$ can be achieved with normalized delay spreads ($\tau_d$) lower than $0.05$. Evaluations are conducted through the first software-defined radio-based field experiments for UG channel. Moreover, …

Towards Internet Of Underground Things In Smart Lighting: A Statistical Model Of Wireless Underground Channel, Abdul Salam, Mehmet C. Vuran, Suat Irmak

School of Computing: Conference and Workshop Papers

The Internet of Underground Things (IOUT) has many applications in the area of smart lighting. IOUT enables communications in smart lighting through underground (UG) and aboveground (AG) communication channels. In IOUT communications, an in-depth analysis of the wireless underground channel is important to design smart lighting solutions. In this paper, based on the empirical and the statistical analysis, a statistical channel model for the UG channel has been developed. The parameters for the statistical tapped-delay-line model are extracted from the measured power delay profiles (PDP). The PDP of the UG channel is represented by the exponential decay of the lateral, …