Now showing items 21-40 of 13155

    • Demonstration of Single-Case Two-Sample Randomization-Test Procedures: Underperforming Children’s Implementation of an Effective Memory Strategy

      Hwang, Yooyeun; Levin, Joel R.; Educational Psychology, University of Arizona (Routledge, 2022-06-01)
      Recently developed randomized-test procedures for two independent-samples single-case designs are presented and applied to a memory-strategy intervention study with eight underperforming students from low SES backgrounds. Research design aspects, data-analysis features, and various output measures are provided to demonstrate the potential utility of the randomization procedures for researchers who seek to examine comparative intervention effects with scarce resources but in a methodologically rigorous manner.
    • Late Holocene human-environment interactions on the central California coast, USA, inferred from Morro Bay salt marsh sediments

      Broadman, Ellie; Reidy, Liam; Wahl, David; Laboratory of Tree-Ring Research, University of Arizona (Elsevier BV, 2022-06)
      Coastal salt marshes and estuaries provide valuable ecosystem services, yet are susceptible to alteration from human activities. Records of past environmental change in these ecosystems can elucidate relationships between human activities, such as land-use practices, and physical and ecological processes, such as sediment accretion and vegetation changes. To reconstruct the environmental history of one such site, we present inferences based on analysis of sediment cores (including magnetic susceptibility, loss-on-ignition, and pollen) from the Morro Bay salt marsh, located in California's central coast in the USA. Chronologic control for the sediments was established using radiocarbon dates, a spike in lead (Pb) sourced from gasoline combustion exhaust, and the first identified occurrences of the non-native taxa Erodium cf. cicutarium (filaree) and Eucalyptus. We demonstrate that the Morro Bay watershed was significantly altered following Spanish settlement in the region. Environmental changes associated with livestock grazing and agriculture become evident in the data starting after 1772 CE, when the Mission San Luis Obispo de Tolosa was established nearby. The most prominent changes observed are an increase in the accumulation rate of terrigenous sediment, organic matter, and carbonates, as well as a reduction in arboreal taxa concomitant with increased abundances of shrubs, herbs, and grasses. The expansion of Salicornia (pickleweed) in the 19th century suggests the salt marsh expanded at this time due to increased sediment accumulation and a resulting increase in local elevation. The timing and character of changes recorded in the Morro Bay salt marsh sediments are similar to those documented across California in estuaries, marshes, lakes, and meadows, demonstrating the magnitude of the impacts of European settlement and associated land-use practices in this region.
    • Geoarchaeology virtual issue: Ancient water management

      Huckleberry, Gary; Department of Geosciences, University of Arizona (Wiley, 2022-06-13)
    • Orbital integrals on GLn× GLn/GL2n

      Xue, Hang; Department of Mathematics, The University of Arizona (Canadian Mathematical Society, 2021-02-26)
      We study harmonic analysis on the symmetric space GLn× GLn/GL2n We prove several standard results, e.g. Shalika germ expansion of orbital integrals, representability of the Fourier transform of orbital integrals and representability of spherical characters. These properties are not expected to hold for symmetric spaces in general.
    • American Heart Association/American Stroke Association Cardiovascular and Stroke Nursing Council: Liaison Report from the Cardiovascular Nursing Clinical Symposium Planning Committee

      Shaffer, Rose B.; Tong, Bonnie Y.; Fink, Anne M.; Taylor-Piliae, Ruth E.; College of Nursing, University of Arizona (Wolters Kluwer Health, 2020-11)
    • ‘No Life Here:’ The Effects of Motion Picture Incentive on Below the Line Labor in Hollywood South

      Lukinbeal, Christopher; Sharp, Laura; University of Arizona, School of Geography Development and Environment (Springer, 2022-04-07)
      In 2002, Louisiana was one of the first states to begin a motion picture incentive (MPI) program to lure film and television production away from Los Angeles. Today, Louisiana, and especially its media capital, New Orleans, has been described as “Hollywood South,” a prominent North American film and television production center. This satellite production center is the outcome of a trend in local and national governments to use MPI programs to encourage the outsourcing of labor from Los Angeles since the mid-1990s. Using in-depth interviews with location managers in Louisiana, a review of policy documents, and an analysis of public discourse around the phenomenon in Louisiana, we examine the geography of Hollywood South, focusing on local labor and the consequences, efficacy, and ethics of its MPI program.
    • Multi-century spatiotemporal patterns of fire history in black pine forests, Turkey

      Şahan, Evrim A.; Köse, Nesibe; Güner, H. Tuncay; Trouet, Valerie; Tavşanoğlu, Çağatay; Akkemik, Ünal; Dalfes, H. Nüzhet; Laboratory of Tree-Ring Research, University of Arizona (Elsevier BV, 2022-08)
      In this study, we aimed to use tree-ring based fire reconstruction to understand the spatiotemporal patterns of past fires in different climate types of western Anatolia. We collected fire scarred wood samples from living trees as wedges and remnant woods from ten sites along a transect that represents a continental to Mediterranean climate gradient. We determined fire years and assigned seasonality of fires based on the intraring position of the fire scars. We calculated fire statistics and analysed fire-climate relationships. Breakpoints in our Anatolian regional fire chronology were estimated to determine the regime shifts. A decrease in fire frequency was recorded at most of the sites after the end of the 19th and the beginning of the 20th century. We observed two critical fire regime shift periods. The period between 1853 and 1934 is characterized by highly frequent (a total of 82 fires) and simultaneous fires occurring in multiple sites and this period overlapped with the longest and most severe drought period of the past 550 years. The fire frequency decline after 1934 coincided with the period of the first forest protection law in 1937. Dry, as well as prior wet conditions were main drivers of fires in the black pine forests in western Anatolia. We observed a decrease in fire frequency in the late 19th and early 20th centuries due to fire suppression activities. Continued fire suppression activities may cause fuel accumulation and pose a risk for more intense fires and thus a paradox for forests in the future. Based on future climate projections, we will face prolonged fire seasons as a consequence of increasing drought frequency, which may shift the fire regime from surface to crown fires with the accumulation of combustible material in the understory in black pine forests.
    • Closed Systems Paradigm for Intelligent Systems

      Shadab, Niloofar; Cody, Tyler; Salado, Alejandro; Beling, Peter; University of Arizona, Department of Systems and Industrial Engineering (IEEE, 2022-04-25)
      Intelligent systems ought to be distinguished as a special type of system. While some adopt this view informally, in practice, systems engineering methods for intelligent systems are still centered around traditional systems engineering notions of engineering by aggregation of components. We posit that this traditional approach follows from holding a notion of open systems as the fundamental precept, and that engineering intelligent systems, in contrast, requires an approach that holds notions of closed systems as fundamental precepts. We take a systems theoretic approach to defining closed system phenomena and their relation to engineering intelligence. We propose the concept of variety; particularly the law of requisite variety to enable closed view in engineering. We discuss how open and closed view approaches to engineering intelligent systems address variety differently, as well as the implications of this difference on engineering practice.
    • A Mean-Field Approximation of SIR Epidemics on an Erdös-Rényi Network Model

      Durón, Christina; Farrell, Alex; Department of Mathematics, University of Arizona (Springer, 2022-05-28)
      The stochastic nature of epidemic dynamics on a network makes their direct study very challenging. One avenue to reduce the complexity is a mean-field approximation (or mean-field equation) of the dynamics; however, the classic mean-field equation has been shown to perform sub-optimally in many applications. Here, we adapt a recently developed mean-field equation for SIR epidemics on a network in continuous time to the discrete time case. With this new discrete mean-field approximation, this proof-of-concept study shows that, given the density of the network, there is a strong correspondence between the epidemics on an Erdös–Rényi network and a system of discrete equations. Through this connection, we developed a parameter fitting procedure that allowed us to use synthetic daily SIR data to approximate the underlying SIR epidemic parameters on the network. This procedure has improved accuracy in the estimation of the network epidemic parameters as the network density increases, and is extremely cheap computationally.
    • High-Resolution Structure of the Nuclease Domain of the Human Parvovirus B19 Main Replication Protein NS1

      Sanchez, Jonathan L; Ghadirian, Niloofar; Horton, Nancy C; BMCB Graduate Program, University of Arizona; Department of Chemistry and Biochemistry, University of Arizona; Department of Molecular and Cellular Biology, University of Arizona (American Society for Microbiology, 2022-04-18)
      Two new structures of the N-terminal domain of the main replication protein, NS1, of human parvovirus B19 (B19V) are presented here. This domain (NS1-nuc) plays an important role in the "rolling hairpin" replication of the single-stranded B19V DNA genome, recognizing origin of replication sequences in double-stranded DNA, and cleaving (i.e., nicking) single-stranded DNA at a nearby site known as the terminal resolution site (trs). The three-dimensional structure of NS1-nuc is well conserved between the two forms, as well as with a previously solved structure of a sequence variant of the same domain; however, it is shown here at a significantly higher resolution (2.4 Å). Using structures of NS1-nuc homologues bound to single- and double-stranded DNA, models for DNA recognition and nicking by B19V NS1-nuc are presented that predict residues important for DNA cleavage and for sequence-specific recognition at the viral origin of replication. IMPORTANCE The high-resolution structure of the DNA binding and cleavage domain of the main replicative protein, NS1, from the human-pathogenic virus human parvovirus B19 is presented here. Included also are predictions of how the protein recognizes important sequences in the viral DNA which are required for viral replication. These predictions can be used to further investigate the function of this protein, as well as to predict the effects on viral viability due to mutations in the viral protein and viral DNA sequences. Finally, the high-resolution structure facilitates structure-guided drug design efforts to develop antiviral compounds against this important human pathogen.
    • The Genomic Origins of the World's First Farmers

      Marchi, Nina; Winkelbach, Laura; Schulz, Ilektra; Brami, Maxime; Hofmanová, Zuzana; Blöcher, Jens; Reyna-Blanco, Carlos S; Diekmann, Yoan; Thiéry, Alexandre; Kapopoulou, Adamandia; et al. (Elsevier B.V., 2022-05-12)
      The precise genetic origins of the first Neolithic farming populations in Europe and Southwest Asia, as well as the processes and the timing of their differentiation, remain largely unknown. Demogenomic modeling of high-quality ancient genomes reveals that the early farmers of Anatolia and Europe emerged from a multiphase mixing of a Southwest Asian population with a strongly bottlenecked western hunter-gatherer population after the last glacial maximum. Moreover, the ancestors of the first farmers of Europe and Anatolia went through a period of extreme genetic drift during their westward range expansion, contributing highly to their genetic distinctiveness. This modeling elucidates the demographic processes at the root of the Neolithic transition and leads to a spatial interpretation of the population history of Southwest Asia and Europe during the late Pleistocene and early Holocene.
    • Use of scheduled and unscheduled health services by cancer survivors and their caregivers

      Sikorskii, Alla; Segrin, Chris; Crane, Tracy E.; Chalasani, Pavani; Arslan, Waqas; Rainbow, Jessica; Hadeed, Mary; Given, Charles; Badger, Terry A.; Department of Communication, University of Arizona; et al. (Springer Science and Business Media LLC, 2022-05-24)
      Purpose The purpose was to determine predictors of scheduled and unscheduled health services use by cancer survivors undergoing treatment and their informal caregivers. Methods English- or Spanish-speaking adult cancer survivors undergoing chemotherapy or targeted therapy for a solid tumor cancer identified a caregiver (N = 380 dyads). Health services use over 2 months was self-reported by survivors and caregivers. Logistic regression models were used to relate the likelihood of service use (hospitalizations, emergency department [ED] or urgent care visits, primary care, specialty care) to social determinants of health (age, sex, ethnicity, level of education, availability of health insurance), and number of comorbid conditions. Co-habitation with the other member of the dyad and other member’s health services use were considered as additional explanatory variables. Results Number of comorbid conditions was predictive of the likelihood of scheduled health services use, both primary care and specialty care among caregivers, and primary care among survivors. Greater probability of specialty care use was associated with a higher level of education among survivors. Younger age and availability of health insurance were associated with greater unscheduled health services use (hospitalizations among survivors and urgent care or ED visits among caregivers). Unscheduled health services use of one member of the dyad was predictive of use by the other. Conclusions These findings inform efforts to optimize health care use by encouraging greater use of scheduled and less use of unscheduled health services. These educational efforts need to be directed especially at younger survivors and caregivers.
    • The Constructionalization of Antonymous Compounds: Evidence from the Adverb Chi-zao in Mandarin Chinese

      Lu, Xiaolong; University of Arizona (John Benjamins Publishing Company, 2022-05-02)
      In modern Chinese, the adverb chi-zao is regarded as an adjective-adjective compound, with morphemes chi ‘late’ and zao ‘early’ as extreme poles in a gradable temporality. The formation of chi-zao as an antonymous compound has not received much attention from a diachronic construction grammar perspective. This study reports on the historical change of chi-zao as evidence showing the interplay of antonymous compounds and constructionalization in modern Chinese. Based on corpus analysis, I found that the formation of chi-zao as a lexical construction inherits from previous changes but emerges instantaneously in Pre-Modern Chinese, where its form has been condensed and its meaning has been bleached to indicate subjectivity. Three arguments shed light on the model of constructionalization: (1) constructionalization at the compound level can be associated with three motivations: subjectivity, frequency, and metaphor; and (2) the operation of constructionalization is at work not only at the sentential and phrasal level but also at the morphological level of compound word formation in Chinese; (3) rhetoric as an output of language use plays a part in the development of constructionalization in relation to antonymous compounds.
    • Optical Hybrid-based Optimal Receiver Design for Entanglement-Assisted Communication

      Bhadani, Rahul; Djordjevic, Ivan B.; Electrical & Computer Engineering, College of Optical Sciences, The University of Arizona (OSA, 2021)
      We propose an optical hybrid (OH) based receiver to discriminate phase-shift-keying modulated information that is transmitted using entanglement-assisted (EA) communication. Our numerical result demonstrates that OH-based receivers perform 10% better in terms of error probability and approximately 50% in terms of Shannon’s capacity compared to the previously proposed receiver design.
    • Happy to take some risk: Estimating the effect of induced emotions on risk preferences

      Kassas, Bachir; Palma, Marco A.; Porter, Maria; Department of Political Economy and Moral Science, University of Arizona (Elsevier BV, 2022-08)
      How do emotions influence one's willingness to take on risk? We show that answering this question can be particularly challenging because induced emotions are highly sensitive to a respondent's contemporaneous experiences and can be rapidly diluted while respondents answer subsequent survey questions. We randomly assign respondents to one of three emotion-inducing videos (positive, negative, and neutral), and we also randomize whether subjects complete a self-assessment survey tool measuring emotions prior to completing risk preference elicitation tasks and immediately after watching the emotion-inducing video. We verify changes in emotions for all respondents by using facial expression analysis software. Respondents who watched a positive video and skipped the emotion-measuring survey were less risk averse, particularly in the first of two preference elicitation tasks. Our findings indicate that estimates of how induced emotions affect risk aversion may be attenuated by including any intermediate tasks, including a survey to measure such emotions. PsychINFO Classification Code: 2360.
    • Enhancing specific energy absorption of additively manufactured titanium lattice structures through simultaneous manipulation of architecture and constituent material

      Zhang, Jingqi; Liu, Yingang; Babamiri, Behzad Bahrami; Zhou, Ying; Dargusch, Matthew; Hazeli, Kavan; Zhang, Ming-Xing; Aerospace and Mechanical Engineering Department, The University of Arizona (Elsevier BV, 2022-07)
      Titanium lattice structures have found a wide range of lightweight applications. However, lattice structures made from the commonly-used commercially pure titanium (CP−Ti) and Ti−6Al−4V exhibit either low strength or post-yielding softening/collapse under uniaxial compression, making them less attractive to energy absorbing applications. In the present work, a series of titanium gyroid lattice structures have been designed and additively manufactured by laser powder bed fusion (L-PBF) to enhance the specific energy absorption (SEA) through manipulation of the architecture and the constituent material. Experimental results show that tailoring the sheet thickness gradient of gyroid lattice structures enables the transformation of the macroscopic deformation mode from hardening followed by softening, which is commonly seen in lattice structures, to continuous hardening. The addition of MgO nanoparticles to CP−Ti feedstock further improves the yield strength through oxygen solute strengthening, while maintaining the continuous hardening behaviour without any post-yielding softening or collapse. As a result, when both sheet thickness gradient and MgO are introduced, the SEA of the uniform gyroid lattice structure is enhanced by approximately 63% due to the combination of continuous hardening behaviour and high strength. Finite element analysis based on the modified volumetric hardening model has been performed to shed light on the underlying mechanism that governs the continuous hardening behaviour. This study demonstrates the tremendous potential of marrying architecture engineering with material design to create high performance lightweight lattice structures by L-PBF.
    • Effects of boron on nutrient partitioning, Ca movement, and fruit quality of tomatoes

      Gholamnejad, Somayeh; Haghighi, Maryam; Etemadi, Nematollah; Pessarakli, Mohammad; School of Plant Sciences, The University of Arizona (Informa UK Limited, 2022-05-09)
      This study was aimed to investigate the effects of boron on Ca movement, yield, and quality of tomatoes. A soilless culture experiment with three levels of B (0, 25, and 50 µM) and three concentrations of Ca (2, 4, and 8 mM) was carried out to grow tomatoes. The results showed that although the application of boron to the sample was more effective in the vegetative growth and the fruit induction, resulting in higher numbers of fruit, the addition of Ca could more effectively enhance the weight and quality of the fruit. With B application, Ca-symplast increased, while pectin methylesterase activity decreased, resulting in less Blossom End Rot indices and more fruit firmness. The Ca-transfer index from apoplast to symplast slightly increased with the B application. Overall, in terms of fruit quality and quantity, the best result was seen in higher Ca application as well as higher B concentrations. Although exogenous boron could help Ca absorption in the root and the shoot, it lowered the Ca transfer from xylem to apoplast and symplast, from shoot to fruit, and from the proximal to distal end of the fruit. Nevertheless, loading 4 and 8 mM of Ca seems to provide enough calcium reserves in fruits to have better quality and yield.
    • Responses of semi-vigorous apple rootstocks (MM106 and MM111) to different nitrate and ammonium ratios under soilless culture

      Yavari, Alimohammad; Habibi, Fariborz; Naseri, Lotfali; Rasouli-Sadaghiani, MirHassan; Sarkhosh, Ali; Pessarakli, Mohammad; School of Plant Sciences, College of Agriculture and Life Sciences, The University of Arizona (Informa UK Limited, 2022-05-09)
      In this study, the effects of nitrate (NO3−) to ammonium (NH4+) ratios on vegetative growth parameters, mineral uptake, physiological and biochemical responses of two semi-vigorous apple rootstocks (MM106 and MM111) in hydroponically grown under greenhouse conditions were evaluated. Treatments were five nutrient solutions of differing NO3−:NH4+ ratios as follows (100:0, 80:20, 60:40, 40:60, 20:80) and two apple rootstocks. After 120 days of treatment, parameters were determined. The NO3−:NH4+ ratios significantly affected the vegetative growth of MM106 and MM111 rootstocks. Rootstocks fertilized with a high NH4+ ratio produced larger leaves, longer roots, stems, and diameter, while the plants under NO3− treatment alone had smaller and shorter roots. N-form significantly influenced the uptake and utilization of essential plant nutrients in both rootstocks. Leaf concentrations of nitrogen (N), potassium (K), and calcium (Ca) were highest with NO3−. Leaf concentrations of phosphorous (P), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) increased as NH4+ supplied more of the N-ratio. The highest chlorophyll a and b and total chlorophyll were observed at the 20:80 NO3−:NH4+ ratio. In comparison, the lowest content was at the highest dose of NO3− (100:0) treatment. The highest soluble sugars were obtained in the leaves of MM106 and MM111 at the ratio of 80:20. Soluble sugars in the root of both rootstocks decreased by increasing the NH4+ ratios in the nutrient solution. Our results show that supplying rootstocks with high NO3− as N form can affect vegetative growth and mineral uptake at this stage of growth.
    • On the importance of electron-electron and electron-phonon scatterings and energy renormalizations during carrier relaxation in monolayer transition-metal dichalcogenides

      Hader, Jörg; Neuhaus, Josefine; Moloney, Jerome V; Koch, Stephan W; Wyant College of Optical Sciences, University of Arizona (IOP Publishing Ltd, 2022-05-12)
      An ab initio based fully microscopic many-body approach is used to study the carrier relaxation dynamics in monolayer transition-metal dichalcogenides. Bandstructures and wavefunctions as well as phonon energies and coupling matrix elements are calculated using density functional theory. The resulting dipole and Coulomb matrix elements are implemented in the Dirac–Bloch equations to calculate carrier–carrier and carrier–phonon scatterings throughout the whole Brillouin zone (BZ). It is shown that carrier scatterings lead to a relaxation into hot quasi-Fermi distributions on a single femtosecond timescale. Carrier cool down and inter-valley transitions are mediated by phonon scatterings on a picosecond timescale. Strong, density-dependent energy renormalizations are shown to be valley-dependent. For MoTe2, MoSe2 and MoS2 the change of energies with occupation is found to be about 50% stronger in the Σ and Λ side valleys than in the K and K' valleys. However, for realistic carrier densities, the materials always maintain their direct bandgap at the K points of the BZ.
    • Organic self-assembled monolayers on superconducting NbSe2: Interfacial electronic structure and energetics

      Ni, Xiaojuan; Li, Hong; Brédas, Jean-Luc; Department of Chemistry and Biochemistry, The University of Arizona; University of Arizona (IOP Publishing, 2022-05-16)
      While organic self-assembled monolayers (SAMs) have been widely used to modify the work function of metal and metal-oxide surfaces, their application to tune the critical temperature of a superconductor has only been considered recently when SAMs were deposited on NbSe2 monolayers (Calavalle et al 2021 Nano Lett. 21 136-143). Here, we describe the results of density functional theory calculations performed on the experimentally reported organic/NbSe2 systems. Our objectives are: (i) to determine how the organic layers impact the NbSe2 work function and electronic density of states; (ii) to understand the possible correlation with the experimental variations in superconducting behavior upon SAM deposition. We find that, upon adsorption of the organic monolayers, the work-function modulation induced by the SAM and interface dipoles is consistent with the experimental results. However, there occurs no significant difference in the electronic density of states near the Fermi level, a consequence of the absence of any charge transfer across the organic/NbSe2 interfaces. Therefore, our results indicate that it is not a SAM-induced tuning of the NbSe2 density of states near the Fermi level that leads to the tuning of the superconducting critical temperature. This calls for further explorations, both experimentally and theoretically, of the mechanism underlying the superconducting critical temperature variation upon formation of SAM/NbSe2 interfaces.