• Computed stabilization for a giant fullerene endohedral: Y2C2@C1(1660)-C108

      Slanina, Zdeněk; Uhlík, Filip; Pan, Changwang; Akasaka, Takeshi; Lu, Xing; Adamowicz, Ludwik; Univ Arizona, Dept Chem & Biochem (Elsevier, 2018-10-16)
    • Constrained vs unconstrained labor supply: the economics of dual job holding

      Choe, Chung; Oaxaca, Ronald L.; Renna, Francesco; Univ Arizona, Dept Econ, Eller Coll Management (SPRINGER, 2018-10)
      This paper develops a unified model of dual and unitary job holding based on a Stone-Geary utility function. The model incorporates both constrained and unconstrained labor supply. Panel data methods are adapted to accommodate unobserved heterogeneity and multinomial selection into six mutually exclusive labor supply regimes. We estimate the wage and income elasticities arising from selection and unobserved heterogeneity as well as from the Stone-Geary Slutsky equations. The labor supply model is estimated with data from the British Household Panel Survey 1991-2008. Among dual job holders, our study finds that the Stone-Geary income and wage elasticities are much larger for labor supply to the second job compared with the main job. When the effects of selection and unobserved heterogeneity are taken account of, the magnitudes of these elasticities on the second job tend to be significantly reduced.
    • Revisiting the Utility of Retrospective Pre-Post Designs: The Need for Mixed-Method Pilot Data

      Geldhof, G. John; Warner, Danielle A.; Finders, Jennifer K.; Thogmartin, Asia A.; Clark, Adam M.; Longway, Kelly A.; Oregon State University; The University of Arizona (Elsevier, 2018-10)
      The retrospective pre-post design affords many benefits to program staff and, accordingly, has piqued renewed interest among applied program evaluators. In particular, the field has witnessed increasing application of a post-program-only data collection strategy in which only posttest and retrospective pretest data are collected. A post-program-only assessment strategy takes considerably less time than is required for collecting pre-program data and presumably has the added benefit of eliminating the impact of response-shift bias. Response-shift bias occurs when the knowledge, skills, or experiences participants gain through program participation leads them to interpret questionnaire items in a qualitatively different manner at pretest versus posttest. In this article, we discuss the strengths and weaknesses associated with administering retrospective pretest assessments and underscore the importance of thoroughly evaluating any application of a retrospective measurement strategy prior to its broader implementation. We provide a practical illustration of this evaluation process using a mixed-method study that assesses one measure of parenting education program effectiveness—the Parenting Skills Ladder.
    • Highly porous defective carbons derived from seaweed biomass as efficient electrocatalysts for oxygen reduction in both alkaline and acidic media

      Hao, Yajuan; Zhang, Xu; Yang, Qifeng; Chen, Kai; Guo, Jun; Zhou, Dongying; Feng, Lai; Slanina, Zdeněk; Univ Arizona, Dept Chem & Biochem (PERGAMON-ELSEVIER SCIENCE LTD, 2018-10)
      In this work, we report a series of defective carbon catalysts prepared through a facile and scalable "-Ndoping-removal" process using seaweed biomass sodium alginate (SA) as precursor. Our systematic studies reveal that the defect content, porosity characteristic and conductivity of defective carbons can be finely tuned by manipulating the pyrolysis temperature and viscosity of precursor polymer SA, which significantly affect the ORR performance. The optimized defective porous carbon catalyst (i.e., D-PC-1( 900)) that was revealed to possess abundant ORR-active defects, large surface area of 1377 m(2)g(-1), abundant hierarchical porosity and good conductivity, exhibited very nice ORR activity and selectivity in 0.1M KOH, comparable to the commercial Pt/C catalyst. In 0.5MH(2)SO(4), considerable ORR activity was also observed for D-PC-1(900), which is among the highest reported for defective carbons and comparable to many of N-doped carbons. Density functional theory calculations indicate that the carbon defect can create the active sites for ORR in acidic media. More importantly, in both alkaline and acidic media, D-PC-1(900) shows much better stability and methanol tolerance than those of the Pt/C catalyst. All these results demonstrate that the seaweed biomass derived defective carbon is an excellent candidate for non-precious-metal ORR catalyst in various fuel cells. (c) 2018 Elsevier Ltd. All rights reserved.
    • Debiased orbit and absolute-magnitude distributions for near-Earth objects

      Granvik, Mikael; Morbidelli, Alessandro; Jedicke, Robert; Bolin, Bryce; Bottke, William F.; Beshore, Edward; Vokrouhlický, David; Nesvorný, David; Michel, Patrick; Univ Arizona (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2018-09-15)
      The debiased absolute-magnitude and orbit distributions as well as source regions for near-Earth objects (NEOs) provide a fundamental frame of reference for studies of individual NEOs and more complex population-level questions. We present a new four-dimensional model of the NEO population that describes debiased steady-state distributions of semimajor axis, eccentricity, inclination, and absolute magnitude H in the range 17 < H < 25. The modeling approach improves upon the methodology originally developed by Bottke et al. (2000, Science 288, 2190-2194) in that it is, for example, based on more realistic orbit distributions and uses source-specific absolute-magnitude distributions that allow for a power-law slope that varies with H. We divide the main asteroid belt into six different entrance routes or regions (ER) to the NEO region: the v(6), 3:1J, 5:2J and 2:1J resonance complexes as well as Hungarias and Phocaeas. In addition we include the Jupiter-family comets as the primary cometary source of NEOs. We calibrate the model against NEO detections by Catalina Sky Surveys' stations 703 and G96 during 2005-2012, and utilize the complementary nature of these two systems to quantify the systematic uncertainties associated to the resulting model. We find that the (fitted) H distributions have significant differences, although most of them show a minimum power-law slope at H similar to 20. As a consequence of the differences between the ER-specific H distributions we find significant variations in, for example, the NEO orbit distribution, average lifetime, and the relative contribution of different ERs as a function of H. The most important ERs are the v(6) and 3:1J resonance complexes with JFCs contributing a few percent of NEOs on average. A significant contribution from the Hungaria group leads to notable changes compared to the predictions by Bottke et al. in, for example, the orbit distribution and average lifetime of NEOs. We predict that there are 962(-56)(+52) (802(-42)(+48) x 10(3)) NEOs with H < 17.75 (H < 25) and these numbers are in agreement with the most recent estimates found in the literature (the uncertainty estimates only account for the random component). Based on our model we find that relative shares between different NEO groups (Amor, Apollo, Aten, Atira, Vatira) are (39.4,54.4,3.5,1.2,0.3)%, respectively, for the considered H range and that these ratios have a negligible dependence on H. Finally, we find an agreement between our estimate for the rate of Earth impacts by NEOs and recent estimates in the literature, but there remains a potentially significant discrepancy in the frequency of Tunguska-sized and Chelyabinsk-sized impacts. (C) 2018 The Authors. Published by Elsevier Inc.
    • Ocean tidal heating in icy satellites with solid shells

      Matsuyama, Isamu; Beuthe, Mikael; Hay, Hamish C.F.C.; Nimmo, Francis; Kamata, Shunichi; Univ Arizona, Lunar & Planetary Lab (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2018-09-15)
      As a long-term energy source, tidal heating in subsurface oceans of icy satellites can influence their thermal, rotational, and orbital evolution, and the sustainability of oceans. We present a new theoretical treatment for tidal heating in thin subsurface oceans with overlying incompressible elastic shells of arbitrary thickness. The stabilizing effect of an overlying shell damps ocean tides, reducing tidal heating. This effect is more pronounced on Enceladus than on Europa because the effective rigidity on a small body like Enceladus is larger. For the range of likely shell and ocean thicknesses of Enceladus and Europa, the thin shell approximation of Beuthe (2016) is generally accurate to less than about 4%. Explaining Enceladus' endogenic power radiated from the south polar terrain by ocean tidal heating requires ocean and shell thicknesses that are significantly smaller than the values inferred from gravity and topography constraints. The time-averaged surface distribution of ocean tidal heating is distinct from that due to dissipation in the solid shell, with higher dissipation near the equator and poles for eccentricity and obliquity forcing, respectively. This can lead to unique horizontal shell thickness variations if the shell is conductive. The surface displacement driven by eccentricity and obliquity forcing can have a phase lag relative to the forcing tidal potential due to the delayed ocean response. For Europa and Enceladus, eccentricity forcing generally produces greater tidal amplitudes due to the large eccentricity values relative to the obliquity values. Despite the small obliquity values, obliquity forcing generally produces larger phase lags due to the generation of Rossby-Haurwitz waves. If Europa's shell and ocean are, respectively, 10 and 100 km thick, the tide amplitude and phase lag are 26.5 m and <1 degrees for eccentricity forcing, and <2.5 m and <18 degrees for obliquity forcing. Measurement of the obliquity phase lag (e.g. by Europa Clipper) would provide a probe of ocean thickness (C) 2018 Elsevier Inc. All rights reserved.
    • HMGB1 binds to the KRAS promoter G-quadruplex: a new player in oncogene transcriptional regulation?

      Amato, Jussara; Madanayake, Thushara W.; Iaccarino, Nunzia; Novellino, Ettore; Randazzo, Antonio; Hurley, Laurence H.; Pagano, Bruno; Univ Arizona, Coll Pharm (ROYAL SOC CHEMISTRY, 2018-09-04)
      This communication reports on a possible distinct role of HMGB1 protein. Biophysical studies revealed that HMGB1 binds and stabilizes the G-quadruplex of the KRAS promoter element that is responsible for most of the transcriptional activity. Biological data showed that inhibition of HMGB1 increases KRAS expression. These results suggest that HMGB1 could play a role in the gene transcriptional regulation via the functional recognition of the G-quadruplex.
    • Profiling caregivers: Hormonal variation underlying allomaternal care in wild red-bellied lemurs, Eulemur rubriventer

      Tecot, Stacey R.; Baden, Andrea L.; Univ Arizona, Sch Anthropol; Univ Arizona, Laboratory for the Evolutionary Endocrinology of Primates (Elsevier, 2018-09-01)
    • Half-Watt Tm3+-Doped Fluoride Fiber Laser at 785 nm

      Mollaee, Masoud; Zhu, Xiushan; Zong, Jie; Wiersma, Kort; Chavez-Pirson, Arturo; Norwood, R. A.; Peyghambarian, N.; Univ Arizona, Coll Opt Sci (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018-09-01)
      All-fiber single-transverse-mode laser oscillators operating at 785 nm were demonstrated by splicing a 0.1 mol% Tm3+-doped fluoride fiber with a core diameter of 4 mu m and a numerical aperture of 0.07 to a pair of silica fiber Bragg gratings. About 500 mW of continuous-wave single transverse mode laser output at 784.5 nm with a 3-dB spectral bandwidth of 0.2 nm was obtained by upconversion pumping a 3-m-long gain fiber at 1125 nm. Our experiments show that the ground-state absorption of Tm3(+ )at 785 nm is the origin of low efficiency in previous reports. The efficiency of this all-fiber laser can be improved by using a gain fiber with an optimized overlap between the laser, the pump, and the fiber core, and employing new pumping schemes that deplete the ground state sufficiently.
    • A lattice QCD study of pion-nucleon scattering in the Roper channel

      Leskovec, Luka; Lang, Christian, B; Padmanath, M.; Prelovsek, Sasa; University of Graz; Regensburg University; University of Ljubljana; Univ Arizona, Dept Phys, Tucson, AZ 85721 USA (SPRINGER WIEN, 2018-09)
      We present a lattice QCD study of the puzzling positive-parity nucleon channel, where the Roper resonance N∗(1440) resides in experiment. The study is based on an ensemble of gauge configurations with Nf=2+1 Wilson-clover fermions with a pion mass of 156 MeV and lattice size L=2.9 fm. We use several qqq interpolating fields combined with Nπ and Nσ two-hadron operators in calculating the energy spectrum in the rest frame. Combining experimental Nπ phase shifts with elastic approximation and the Lüscher formalism suggests in the spectrum an additional energy level near the Roper mass mR=1.43 GeV for our lattice. We do not observe any such additional energy level, which implies that Nπ elastic scattering alone does not render a low-lying Roper resonance. The current status indicates that the N∗(1440) might arise as dynamically generated resonance from coupling to other channels, most notably the Nππ .
    • Adsorption and oxidation of 3-nitro-1,2,4-triazole-5-one (NTO) and its transformation product (3-amino-1,2,4-triazole-5-one, ATO) at ferrihydrite and birnessite surfaces

      Khatiwada, Raju; Abrell, Leif; Li, Guangbin; Root, Robert A.; Sierra-Alvarez, Reyes; Field, James A.; Chorover, Jon; Univ Arizona, Dept Soil Water & Environm Sci; Univ Arizona, Arizona Lab Emerging Contaminants; Univ Arizona, Dept Chem & Environm Engn (ELSEVIER SCI LTD, 2018-09)
      The emerging insensitive munitions compound (IMC) 3-nitro-1,2,4-triazole-5-one (NTO) is currently being used to replace conventional explosives such as 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but the environmental fate of this increasingly widespread IMC remains poorly understood. Upon release from unexploded solid phase ordinances, NTO exhibits high aqueous solubility and, hence, potential mobilization to groundwater. Adsorption and abiotic transformation at metal oxide surfaces are possible mechanisms for natural attenuation. Here, the reactions at ferrihydrite and birnessite surfaces of NTO and its biotransformation product, 3-amino-1, 2, 4-triazol-5-one (ATO), were studied in stirred batch reactor systems at controlled pH (7.0). The study was carried out at metal oxide solid to solution ratios (SSR) of 0.15, 1.5 and 15 g kg(-1). The samples were collected at various time intervals up to 3 h after reaction initiation, and analyzed using HPLC with photodiode array and mass spectrometric detection. We found no detectable adsorption or transformation of NTO upon reaction with birnessite, whereas ATO was highly susceptible to oxidation by the same mineral, showing nearly complete transformation within 5 min at 15 g kg(-1) SSR to urea, CO2(g) and N-2(g). The mean surface-area-normalized pseudo-first order rate constant (k) for ATO oxidation by birnessite across all SSRs was 0.05 +/- 0.022 h(-1) m(-2), and oxidation kinetics were independent of dissolved O-2 concentration. Both NTO and ATO were resistant to oxidation by ferrihydrite. However, NTO showed partial removal from solution upon reaction with ferrihydrite at 0.15 and 1.5 g kg(-1) SSR and complete loss at 15 g kg(-1) SSR due to strong adsorption. Conversely, ATO adsorption to ferrihydrite was much weaker than that measured for NTO. (C) 2018 Published by Elsevier Ltd.
    • Theoretically exact photoacoustic reconstruction from spatially and temporally reduced data

      Do, N; Kunyansky, L; Univ Arizona, Dept Math (IOP PUBLISHING LTD, 2018-09)
      We investigate the inverse source problem for the wave equation, arising in photo- and thermoacoustic tomography. There exist quite a few theoretically exact inversion formulas explicitly expressing the solution of this problem in terms of the measured data, under the assumption of the constant and known speed of sound. However, almost all of these formulas require data to be measured either on an unbounded surface, or on a closed surface completely surrounding the object. This is too restrictive for practical applications. The alternative approach we present, under certain restriction on geometry, yields a theoretically exact reconstruction of the standard Radon projections of the source from the data measured on a finite open surface. In addition, this technique reduces the time interval where the data should be known. In general, our method requires a pre-computation of densities of certain single-layer potentials. However, in the case of a truncated circular or spherical acquisition surface, these densities are easily obtained analytically, which leads to fully explicit asymptotically fast algorithms. We test these algorithms in a series of numerical simulations.
    • Detransformation Bias in Nonlinear Trip Generation Models

      Wang, Liming; Currans, Kristina M.; Univ Arizona, Sch Landscape Architecture & Planning (ASCE-AMER SOC CIVIL ENGINEERS, 2018-09)
      In recent years, there have been substantial efforts from researchers and practitioners to improve site-level trip generation estimation methods to address some of the pitfalls of conventional approaches for applications such as traffic impact analyses. These new trip generation models often adopt sophisticated nonlinear model forms to utilize new information and incorporate new factors influencing trip generation. However, if sufficient caution is not taken in their application, these new predictive models may introduce severe bias. This paper focuses on a typical source of biases in the applications of such models arising from detransformation of predictions from models with a nonlinearly transformed dependent variable in the prediction process (for example, predicting from a semilog model). While such biases are well known and corrections have been proposed in other disciplines, they have not been adopted in site-level trip generation models to the authors' knowledge. The detransformation bias is described and demonstratedfocusing on log-transformed modelswith numeric simulations and empirical studies of trip generation models, before discussing their implications for trip generation applications and research.
    • Atomistic simulation of shape memory effect (SME) and superelasticity (SE) in nano-porous NiTi shape memory alloy (SMA)

      Gur, Sourav; Frantziskonis, George N.; Muralidharan, Krishna; Univ Arizona, Civil Engn & Engn Mech; Univ Arizona, Mat Sci & Engn (ELSEVIER SCIENCE BV, 2018-09)
      Porosity can play an important role in altering the phase transformation characteristics of NiTi shape memory alloys (SMA), thus changing its shape memory as well as its superelasticity properties. This work, based on atomistic simulations of binary NiTi SMA, documents the effects of porosity at the nanometer length scale on phase fraction evolution kinetics, transformation temperatures, and stress-strain response. Classical molecular dynamics simulations are performed using a well-examined and verified Finnis-Sinclair type embedded-atom method interatomic potential. Simulation results for the nano-porous NiTi with various porosity configurations are compared to non-porous NiTi. The martensite phase fraction and transformation temperatures increase noticeably with increasing porosity, and the stress-strain response shows noticeable variation with porosity. The residual strain and hysteretic energy dissipation capacity increase significantly with increasing porosity.
    • Antiwindup Terminal Sliding Mode Control for Mars Entry Using Supertwisting Sliding Mode Disturbance Observer

      Jiang, Xiuqiang; Li, Shuang (AMER SOC CIVIL ENGINEERS, 2018-09)
      Uncertainty and external disturbance during the Mars entry process inevitably degrade the performance of Mars entry guidance and control algorithms. Traditional approaches focus on suppressing disturbances and compensating uncertainties, which usually results in larger control responses beyond the limited control capability of a Mars entry vehicle. This paper further takes the limited actuator ability into consideration and proposes the Mars entry robust attitude control strategy using the terminal sliding mode control (TSMC) with antiwindup (AW) and a supertwisting sliding mode disturbance observer (SMDO). First, terminal sliding mode control with antiwindup is developed to robustly track the nominal attitude command under uncertainty and limited control capability. Then, the supertwisting sliding mode disturbance observer is introduced to online estimate the disturbances and further enhance the attitude control accuracy and robustness. Finally, the comparison simulation results illustrate that the proposed control strategy not only performs well in tracking the reference commands even in the presence of uncertain disturbance, but also avoids the control saturation issue.
    • Does Desperation Breed Deceiver? A Behavioral Model of New Venture Opportunism

      Jiang, Han; Cannella, Albert A.; Jiao, Jie; Univ Arizona, Dept Management & Org, Eller Coll Management (WILEY, 2018-09)
      We develop a behavioral-decision model to highlight entrepreneurs' decision making behind venture opportunism. We find that opportunism can present to entrepreneurs and their new ventures a risky yet beneficial choice to secure short-term gains at potential social costs. We posit that, motivated by loss aversion, entrepreneurs may accept the risk and engage in opportunism when their ventures confront economic losses. For instance, a high risk of venture failure may motivate entrepreneurs to act opportunistically in the hope that the failure can be averted. We further posit that such loss-averse decisions will be moderated by the entrepreneurs' personal bonds to their new ventures. That is, the scale of entrepreneurs' personal investment in their ventures will intensify their economic loss aversion posed by venture failure risk. In contrast, when entrepreneurs use their personal social capital to support their ventures, they will personally bear more of the down-side risks of opportunistic behavior and thus be less likely to act opportunistically to countervail a potential economic loss. Results based on the data collected from 244 NEEQ-listed new ventures in Beijing and Tianjin in China support our predictions.
    • Task-Specific Sites and Paleoindian Landscape Use in the Shaw Creek Flats, Alaska

      Lanoë, François B.; Reuther, Joshua D.; Holmes, Charles E.; Univ Arizona, Sch Anthropol (SPRINGER, 2018-09)
      The Shaw Creek Flats and nearby middle Tanana river, in central Alaska, constitute one of the areas in the Americas with the densest known distribution of Late Glacial (about 14,500-11,700 cal. B.P.) archaeological sites. Local high rates of sediment deposition and low post-depositional disturbance allow for the interpretation of the function of archaeological occupations within larger economic and mobility strategies. Residential sites used over the long term seem to be located near critical but immovable resources such as clear water and vegetation. The spatial association of artifacts and faunal remains at other sites in the Flats suggest that they were specialized, short-lived locations dedicated to a single or few activities. For instance, the site of Swan Point Cultural Zone 4b is interpreted as a workshop related to the production of composite tools, particularly on mammoth ivory, and the site of Keystone Dune is interpreted as a camp related to wapiti (Cervus elaphus) hunting. These task-specific sites and others were probably used as part of a predominantly logistical mobility and economy strategy, which maximized efficiency in harvesting and processing resources that were distributed heterogeneously on the landscape.
    • Quit Outcomes and Program Utilization by Mode of Entry Among Clients Enrolling in a Quitline

      Nair, Uma S.; Reikowsky, Ryan C.; Wertheim, Betsy C.; Thomson, Cynthia A.; Gordon, Judith S.; Univ Arizona, Mel & Enid Zuckerman Coll Publ Hlth; Univ Arizona, Canc Ctr; Univ Arizona, Coll Nursing (SAGE PUBLICATIONS INC, 2018-09)
      Purpose: To investigate how mode of entry into a quitline influences program utilization and quit outcomes among clients seeking cessation services. Design: This is a retrospective analysis of clients receiving quitline services from January 2011 to June 2016. Setting: The study was conducted at the Arizona Smokers' Helpline. Participants: Enrolled clients completed a 7-month follow-up (N = 18 650). Measures: The independent variable was referral mode of entry (ie, proactive, passive, and self-referral). Outcome variables included tobacco cessation medication use, number of coaching sessions completed, and 30-day tobacco abstinence at 7 months. Analysis: Logistic regression was used to analyze tobacco abstinence after controlling for potential confounders. Results: Compared to self-referred clients, proactively referred clients were least likely (odds ratio [OR]: 0.88; 95% confidence interval [CI]: 0.81-0.97), whereas passively referred clients were most likely (OR: 1.14; 95% CI: 1.00-1.30) to report tobacco abstinence. Proactively referred (OR: 0.79; 95% CI: 0.70-0.88), but not passively referred, clients were 21% less likely to report tobacco cessation medication use than self-referred clients. Conclusion: Proactive referrals are associated with lower utilization of tobacco cessation medication and less successful quit outcomes; however, provider referrals are critical to reaching tobacco users who may have more significant health risks and barriers to quitting. Examining potential barriers among both providers and provider-referred clients is needed to inform improvements in training providers on brief interventions for tobacco cessation.
    • Approaches to community consultation in exception from informed consent: Analysis of scope, efficiency, and cost at two centers

      Eubank, Louis; Lee, Kwan S.; Seder, David B.; Strout, Tania; Darrow, Matthew; MacDonald, Catherine; May, Teresa; Riker, Richard R.; Kern, Karl B.; Univ Arizona, Div Cardiol, Sarver Heart Ctr (ELSEVIER IRELAND LTD, 2018-09)
      Objectives: Community consultation (CC) is fundamental to the Exception from Informed Consent (EFIC) process for emergency research, designed to inform and receive feedback from the target study population about potential risks and benefits. To better understand the effectiveness of different techniques for CC, we evaluated EFIC processes at two centers participating in a trial of early cardiac catheterization following out-of-hospital cardiac arrest. Methods: We studied the Institutional Review Board-approved CC activities at Maine Medical Center (MMC) and University of Arizona (AZ) in support of NCT02387398. In Maine, the public was consulted by survey at a professional basketball game and in the emergency department waiting room (in-person group), by multimedia direction to an online website (online group), and by mail (mailing group). Arizona respondents were either approached at a county fair (in-person group) or were directed to an online survey (online group) via social media advertising. Results: Among 2185 survey respondents, approval rates were high for community involvement and personal participation without individual consent. Community consultation using in-person, online, and mailed surveys offered slightly different approval rates, and the rate of responses by modality differed by age and education level but not ethnicity. Print advertising was the least cost effective at $ 442 per completed survey. Conclusions: Canvassing at public events was the most efficient mode of performing CC, with approval rates similar to mailings, online surveys, and canvassing in other locations. Print advertisements in local papers had a low yield and cost more than other approaches.
    • Does policy uncertainty affect mergers and acquisitions?

      Bonaime, Alice; Gulen, Huseyin; Ion, Mihai; Univ Arizona, Eller Coll Management (ELSEVIER SCIENCE SA, 2018-09)
      Political and regulatory uncertainty is strongly negatively associated with merger and acquisition activity at the macro and firm levels. The strongest effects are for uncertainty regarding taxes, government spending, monetary and fiscal policies, and regulation. Consistent with a real options channel, the effect is exacerbated for less reversible deals and for firms whose product demand or stock returns exhibit greater sensitivity to policy uncertainty, but attenuated for deals that cannot be delayed due to competition and for deals that hedge firm-level risk. Contractual mechanisms (deal premiums, termination fees, MAC clauses) unanimously point to policy uncertainty increasing the target's negotiating power. Published by Elsevier B.V.