• AMS 14C Dating of the Mayan Codex of Mexico Revisited

      Solís, Corina; Martínez Carrillo, Miguel Á; Rodríguez-Ceja, María; Chávez, Efraín; Christen, J Andrés; Jull, A J Timothy; Department of Geosciences, University of Arizona; University of Arizona AMS Laboratory (Cambridge University Press (CUP), 2020-09-01)
      The Mayan Codex of Mexico (MCM), the only Mayan codex found in the 20th century, was unveiled in 1971 during the Ancient Maya Calligraphy exhibition at Club Grolier. The codex comprises 10 pages of bark paper in accordion format, coated with a layer of plaster on both sides. It illustrates the synodic cycles of Venus, with its four phases. Since its discovery, the MCM has been subject to controversy and discussions about its authenticity. In 2016, a group of specialists led by Baltazar Brito chief of the National Library of Anthropology and History, carried out an exhaustive study of the codex with the purpose of determining its temporality and authenticity. In this work, the pre-Columbian authenticity of the codex is verified by the radiocarbon (14C) technique using AMS. Two cleaning procedures were contrasted: the standard acid-base-acid (ABA) protocol and a second one with Soxhlet plus ABA. Results obtained when samples were prepared following ABA protocol only, placed the age of the bark paper between 991 and 1147 cal AD. The second cleaning method with Soxhlet plus ABA, resulted in younger ages, between 1159 and 1261 cal AD. However, we consider that when Sohxlet is used as part of the cleaning protocol, organic contaminants are reduced to a minimum, and 14C dates are more reliable. These results indicate that the vegetal support of the MCM belongs to Postclassical Mayan period and place it as the oldest known manuscript of America found to date.
    • Diagnosing collisionless energy transfer using field–particle correlations: Alfvén-ion cyclotron turbulence

      Klein, Kristopher G.; Howes, Gregory G.; TenBarge, Jason M.; Valentini, Francesco; Univ Arizona, Lunar & Planetary Lab (Cambridge University Press (CUP), 2020-07-24)
      We apply field-particle correlations - a technique that tracks the time-averaged velocity-space structure of the energy density transfer rate between electromagnetic fields and plasma particles - to data drawn from a hybrid Vlasov-Maxwell simulation of Alfven-ion cyclotron turbulence. Energy transfer in this system is expected to include both Landau and cyclotron wave-particle resonances, unlike previous systems to which the field-particle correlation technique has been applied. In this simulation, the energy transfer rate mediated by the parallel electric field E-parallel to comprises approximately 60% of the total rate, with the remainder mediated by the perpendicular electric field E-perpendicular to. The parallel electric field resonantly couples to protons, with the canonical bipolar velocity-space signature of Landau damping identified at many points throughout the simulation. The energy transfer mediated by E-perpendicular to preferentially couples to particles with v(tp) less than or similar to v(perpendicular to) less than or similar to 3 v(tp), where vtp is the proton thermal speed, in agreement with the expected formation of a cyclotron diffusion plateau. Our results demonstrate clearly that the field-particle correlation technique can distinguish distinct channels of energy transfer using single-point measurements, even at points in which multiple channels act simultaneously, and can be used to determine quantitatively the rates of particle energization in each channel.
    • How Alfvén waves energize the solar wind: heat versus work

      Perez, Jean C.; Chandran, Benjamin D. G.; Klein, Kristopher G.; Martinović, Mihailo M.; Lunar and Planetary Laboratory, University of Arizona (Cambridge University Press (CUP), 2021-04-14)
      A growing body of evidence suggests that the solar wind is powered to a large extent by an Alfvén-wave (AW) energy flux. AWs energize the solar wind via two mechanisms: heating and work. We use high-resolution direct numerical simulations of reflection-driven AW turbulence (RDAWT) in a fast-solar-wind stream emanating from a coronal hole to investigate both mechanisms. In particular, we compute the fraction of the AW power at the coronal base (PAWb) that is transferred to solar-wind particles via heating between the coronal base and heliocentric distance r, which we denote by χH(r), and the fraction that is transferred via work, which we denote by χW(r). We find that χW(rA) ranges from 0.15 to 0.3, where rA is the Alfvén critical point. This value is small compared with one because the Alfvén speed vA exceeds the outflow velocity U at r<rA, so the AWs race through the plasma without doing much work. At r>rA, where vA<U, the AWs are in an approximate sense ‘stuck to the plasma’, which helps them do pressure work as the plasma expands. However, much of the AW power has dissipated by the time the AWs reach r=rA, so the total rate at which AWs do work on the plasma at r>rA is a modest fraction of PAWb. We find that heating is more effective than work at r<rA, with χH(rA) ranging from 0.5 to 0.7. The reason that χH≥0.5 in our simulations is that an appreciable fraction of the local AW power dissipates within each Alfvén-speed scale height in RDAWT, and there are a few Alfvén-speed scale heights between the coronal base and rA. A given amount of heating produces more magnetic moment in regions of weaker magnetic field. Thus, paradoxically, the average proton magnetic moment increases robustly with increasing r at r>rA, even though the total rate at which AW energy is transferred to particles at r>rA is a small fraction of PAWb.
    • The Journey Home: Violence, Anchoring, and Refugee Decisions to Return

      Ghosn, Faten; Chu, Tiffany S.; Simon, Miranda; Braithwaite, Alex; Frith, Michael; Jandali, Joanna; School of Government and Public Policy, University of Arizona (Cambridge University Press (CUP), 2021-05-17)
      While the UNHCR promotes voluntary repatriation as the preferred solution to refugee situations, there is little understanding of variation in refugees' preferences regarding return. We develop a theoretical framework suggesting two mechanisms influencing refugees' preferences. First, refugees' lived experiences in their country of origin prior to displacement and in their new host country create a trade-off in feelings of being anchored to their origin or host country. Second, firsthand exposure to traumas of war provides some refugees with a sense of competency and self-efficacy, leading them to prefer to return home. We test these relationships with data from a survey among Syrian refugees hosted in Lebanon. We find refugees exposed to violence during the war have a sense of attachment to Syria and are most likely to prefer return. Refugees who have developed a detachment from Syria or an attachment to Lebanon are less likely to prefer return.
    • Omissions, Moral Luck, and Minding the (Epistemic) Gap

      Metz, Joseph; Department of Philosophy, University of Arizona (Cambridge University Press (CUP), 2021-08-20)
      This paper warns of two threats to moral responsibility that arise when accounting for omissions, given some plausible assumptions about how abilities are related to responsibility. The first problem threatens the legitimacy of our being responsible by expanding the preexisting tension that luck famously raises for moral responsibility. The second threat to moral responsibility challenges the legitimacy of our practices of holding responsible. Holding others responsible for their omissions requires us to bridge an epistemic gap that does not arise when holding others responsible for their actions-one that we might often fail to cross.
    • SARS-CoV-2 (COVID-19) Vaccine Development and Production: An Ethical Way Forward

      Iserson, Kenneth V.; Univ Arizona, Dept Emergency Med (Cambridge University Press (CUP), 2020-06-05)
      The world awaits a SARS-CoV-2 virus (i.e., COVID-19 disease) vaccine to keep the populace healthy, fully reopen their economies, and return their social and healthcare systems to “normal.” Vaccine safety and efficacy requires meticulous testing and oversight; this paper describes how despite grandiose public statements, the current vaccine development, testing, and production methods may prove to be ethically dubious, medically dangerous, and socially volatile. The basic moral concern is the potential danger to the health of human test subjects and, eventually, many vaccine recipients. This is further complicated by economic and political pressures to reduce government oversight on rushed vaccine testing and production, nationalistic distribution goals, and failure to plan for the widespread immunization needed to produce global herd immunity. As this paper asserts, the public must be better informed to assess promises about the novel vaccines being produced and to tolerate delays and uncertainty.
    • The Shadow Effect of Courts: Judicial Review and the Politics of Preemptive Reform

      Pavone, T.; Stiansen, Ø.; School of Government and Public Policy, University of Arizona (Cambridge University Press (CUP), 2021-08-26)
      We challenge the prevalent claim that courts can only influence policy by adjudicating disputes. Instead, we theorize the shadow effect of courts: policy makers preemptively altering policies in anticipation of possible judicial review. While American studies imply that preemptive reforms hinge on litigious interest groups pressuring policy makers who support judicial review, we advance a comparative theory that flips these presumptions. In less litigious and more hostile political contexts, policy makers may instead weaponize preemptive reforms to preclude bureaucratic conflicts from triggering judicial oversight and starve courts of the cases they need to build their authority. By allowing some preemptive judicial influence to resist direct judicial interference, recalcitrant policy makers demonstrate that shadow effects are not an unqualified good for courts. We illustrate our theory by tracing how a major welfare reform in Norway was triggered by a conflict within its Ministry of Labor and a government resistance campaign targeting a little-known international court.
    • Teaching drunk: Work, the online economy, and uncertainty in action

      Kramer, Max F.; Department of Philosophy and Program in Cognitive Science, University of Arizona (Cambridge University Press (CUP), 2021-05-14)
      Technological developments have led to the digitization of certain sectors of the economy, and this has many authors looking ahead to the prospects of a post-work society. While it is valuable to theorize about this possibility, it is also important to take note of the present state of work. For better or worse, it is what we are currently stuck with, and as the COVID-19 pandemic has ensured, much of that work is now taking place online. Though a 'return to normalcy' is on the horizon, part of that normalcy involves online work, which is itself a significant change in the lives of many workers. Here I develop an account of work on which work is teleologically structured. This gives the result that working is something we can fail at doing, even when we try, and we can also be unsure of whether we've succeeded or failed. The shift of certain work from in-person to online modes generates a persistent uncertainty for workers in affected professions. Because our ability to work is something we typically value, this uncertainty has significant negative consequences for a worker's self-conception. Indeed, it is analogous to disorders of agency and generates a kind of alienation.
    • Vegetation classification enables inferring mesoscale spatial variation in plant invasibility

      Li, Yue M.; Stauffer, Brett; Malusa, Jim; Univ Arizona, Sch Nat Resources & Environm (Cambridge University Press (CUP), 2019-10-04)
      Large-scale control of invasive plants can benefit strongly from reliable assessment of spatial variation in plant invasibility. With this knowledge, limited management resources can be concentrated in areas of high invasion risk. We assessed the influence of spatial environments and proximity to roads on the invasibility of African mustard (Brassica tournefortii Gouan) over the 280,000-ha Barry M. Goldwater Range West in southwestern Arizona, USA. We used presence/absence data of B. tournefortii acquired from a vegetation classification project, in which lands were mapped to the level of vegetation subassociations. Logistic regression models suggested that spatial environments represented by the subassociations, not proximity to roads, represented the only factor significantly explaining B. tournefortii presence. We then used the best model to predict B. tournefortii invasibility in each subassociation. This prediction indicates management strategy should differ between the western part and the central to eastern part of the range. The western range is a large spatial continuum with intermediate to high invasion risk, vulnerable to an untethered spread of B. tournefortii. Controlling efforts should focus on preventing existing local populations from further expansion. The central and eastern ranges are a mosaic varying strongly in invasion risk. Control efforts can take advantage of natural invasion barriers and further reduce connectivity through removal of source populations connected with other high-risk locations via roads and other dispersal corridors. We suggest our approach as one effective way to combine vegetation classification and plant invasion assessment to manage complex landscapes over large ranges, especially when this approach is used through an iterative prediction-validation process to achieve adaptive management of invasive plants.
    • Why Are Bidder Termination Provisions Included In Takeovers?

      Chen, Zhiyao; Mahmudi, Hamed; Virani, Aazam; Zhao, Xiaofei; University of Arizona, Eller College of Management (Cambridge University Press (CUP), 2021-08-10)
      We present a rationale for bidder termination provisions that considers their effect on bidders' and targets' joint takeover gains. The provision's inclusion can create value by enabling termination when the target becomes less valuable to the bidder than on its own, but creates a trade-off because termination may also occur when the target is more valuable to the bidder than on its own. This trade-off explains why the provision is included in only some deals, and explains variation in termination fees. Inclusion of the provision is associated with larger combined announcement returns, provided that the termination fee is priced appropriately.
    • Worship: bowing down in the service of God

      Levi, Avital Hazony; Department of Philosophy, University of Arizona (Cambridge University Press (CUP), 2021-04-05)
      Philosophers commonly assume that worship is a universal attitude. Two major approaches see worship as a sui generis attitude or as the specific attitude of respect. This article criticizes the universal assumption and defines worship as a ritual that shapes a person in acquiring the attitude considered appropriate in relating to a superior such as God. Religions differ in their rituals of worship because they disagree on what this appropriate attitude is. This claim is demonstrated by distinguishing the Hebrew Bible's form of worship as bowing down. Biblical worship is shown to be political, forming the worshipper into a loyal servant of God as king. This form of worship is argued to be fundamentally ethical because it teaches that the individual's relationship with God supervenes on human relationships.