Horseshoe drag in three-dimensional globally isothermal disks

We study the horseshoe dynamics of a low-mass planet in a three-dimensional, globally isothermal, inviscid disk. We find, as reported in previous work, that the boundaries of the horseshoe region (separatrix sheets) have cylindrical symmetry about the disk´s rotation axis. We interpret this feature as arising from the fact that the whole separatrix sheets have a unique value of Bernoulli´s constant, and that this constant does not depend on altitude, but only on the cylindrical radius, in barotropic disks. We next derive an expression for the torque exerted by the horseshoe region on the planet, or horseshoe drag. Potential vorticity is not materially conserved as in two-dimensional flows, but it obeys a slightly more general conservation law (Ertel´s theorem) that allows an expression for the horseshoe drag identical to the expression in a two-dimensional disk to be obtained. Our results are illustrated and validated by three-dimensional numerical simulations. The horseshoe region is found to be slightly narrower than previously extrapolated from two-dimensional analyses with a suitable softening length of the potential. We discuss the implications of our results for the saturation of the corotation torque, and the possible connection to the flow at the Bondi scale, which the present analysis does not resolve.Fil: Masset, F. S.. Universidad Nacional Autónoma de México; MéxicoFil: Benítez Llambay, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin

FARGO3D: A new GPU-oriented MHD code

We present the FARGO3D code, recently publicly released. It is a magnetohydrodynamics code developed with special emphasis on the physics of protoplanetary disks and planet-disk interactions, and parallelized with MPI. The hydrodynamics algorithms are based on finite-difference upwind, dimensionally split methods. The magnetohydrodynamics algorithms consist of the constrained transport method to preserve the divergence-free property of the magnetic field to machine accuracy, coupled to a method of characteristics for the evaluation of electromotive forces and Lorentz forces. Orbital advection is implemented, and an N-body solver is included to simulate planets or stars interacting with the gas. We present our implementation in detail and present a number of widely known tests for comparison purposes. One strength of FARGO3D is that it can run on either graphical processing units (GPUs) or central processing units (CPUs), achieving large speed-up with respect to CPU cores. We describe our implementation choices, which allow a user with no prior knowledge of GPU programming to develop new routines for CPUs, and have them translated automatically for GPUs.Fil: Benítez Llambay, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Masset, Frédéric S.. Universidad Nacional Autónoma de México; Méxic

Expectation Formation of Older Married Couples and the Rational Expectations Hypothesis

This paper tests the Rational Expectations (RE) hypothesis regarding retirement expectations of married older American couples, controlling for sample selection and reporting biases. In prior research we found that individual retirement expectation formation was consistent with the Rational Expectation hypothesis, but in that work spousal considerations were not analyzed. In this research we take advantage of panel data on expectations to test the RE hypothesis among married individuals as well as joint expectations among couples. We find that regardless of whether we assume that married individuals form their own expectations taking spouse’s information as exogenous, or the reports of the couple are the result of a joint expectation formation process, their expectations are consistent with the RE hypothesis. Our results support a wide variety of models in economics that assume rational behavior for married couples.

What to Expect when you are Expecting Rationality: Testing Rational Expectations using Micro Data

This paper tests the Rational Expectations (RE) hypothesis regarding retirement expectations, controlling for sample selection, reporting biases, and unobserved heterogeneity. We find that retirement expectations in the Health and Retirement Study (HRS) are consistent with the RE hypothesis. We also examine how a wide array of factors, such as wealth, income, health insurance, pensions, and health status influence retirement expectations formation using panel data from all available waves of the HRS. We further analyze how new information affects the evolution of retirement expectations and discover that, on average, individuals correctly anticipate most uncertain events when planning their retirement, except for some health conditions and economic factors. Our results have important implications for a wide variety of models in economics that assume rational behavior.

Long-term and large-scale hydrodynamical simulations of migrating planets

We present a new method that allows long-term and large-scale hydrodynamical simulations of migrating planets over a grid-based Eulerian code. This technique, which consists in a remapping of the disk by tracking the planetary migration, enables runs of migrating planets over a time comparable to the age of protoplanetary disks. This method also has the potential to address efficiently problems related with migration of multi-planet systems in gaseous disks, and to improve current results of migration of massive planets by including global viscous evolution as well as detailed studies of the co-orbital region during migration. We perform different tests using the public code FARGO3D to validate this method and compare its results with those obtained using a classical fixed grid.Comment: Accepted for publication in ApJ. For a movie describing the method, see https://youtu.be/66o0Z2lX8N

High pCO 2 levels affect metabolic rate, but not feeding behavior and fitness, of farmed giant mussel Choromytilus chorus

Indexación: Scopus.Acknowledgements. We thank Luisa Saavedra and Araceli Rodriguez-Romero for their help in the field and during laboratory activities. We also acknowledge Laura Ramajo for help with AT estimations. Emily Giles Neill provided valuable comments that greatly improved the manuscript. Special thanks are due to the reviewers and the editor for very constructive comments on the manuscript. This study was supported by the Millennium Nucleus Center for the Study of Multiple drivers on Marine Socio-Ecological Systems (MUSELS) funded by MINECON NC120086, PIA CONICYT ACT-172037 and FONDECYT grant nos. 1140938 and 1140092 to N.A.L. and M.A.L.Mar Ecol Prog Ser 454: 65−74 Findlay HS, Wood HL, Kendall MA, Spicer JI, Twitchett RJ, Widdicombe S (2009) Calcification, a physiological pro-cess to be considered in the context of the whole organ-ism. Biogeosciences 6: 2267−2284 Fitzer SC, Zhu W, Tanner KE, Phoenix VR, Kamenos NA, Cusack M (2015) Ocean acidification alters the material properties of Mytilus edulis shells. J R Soc Interface 12: 214−227 Freitas R, De Marchi L, Bastos M, Moreira A and others (2017) Effects of seawater acidification and salinity alter-ations on metabolic, osmoregulation and oxidative stress markers in Mytilus galloprovincialis. Ecol Indic 79: 54−62 Gattuso JP, Magnan A, Billé R, Cheung WWL and others (2015) Contrasting futures for ocean and society from dif-ferent anthropogenic CO2 emissions scenarios. Science 349: aac4722 Gazeau F, Urbini L, Cox TE, Alliouane S, Gattuso JP (2015) Comparison of the alkalinity and calcium anomaly tech-niques to estimate rates of net calcification. Mar Ecol Prog Ser 527: 1−12 Gray MW, Langdon CJ, Waldbusser GG, Hales B, Kramer S (2017) Mechanistic understanding of ocean acidification impacts on larval feeding physiology and energy budg-ets of the mussel Mytilus californianus. Mar Ecol Prog Ser 563: 81−94 Griffiths CL, Griffiths RJ (1987) Animal energetics, Vol 2: Bivalvia through Reptilia. In: Pandian TJ, Vernberg FJ (eds) Bivalvia. Academic Press, New York, NY, p 1−88 Harvey BP, Dwynn-Jones D, Moore PJ (2013) Meta-analysis reveals complex marine biological responses to the inter-active effects of ocean acidification and warming. Ecol Evol 3: 1016−1030 Hiebenthal C, Philipp EER, Eisenhauer A, Wahl M (2013) Effects of seawater pCO2 and temperature on shell growth, shell stability, condition and cellular stress of western Baltic Sea Mytilus edulis (L.) and Arctica is - landica (L.). Mar Biol 160: 2073−2087 Ibarrola I, Arambalza U, Navarro JM, Urrutia MB, Navarro E (2012) Allometric relationships in feeding and diges-tion in the Chilean mytilids Mytilus chilensis (Hupé), Choromytilus chorus (Molina) and Aulacomya ater (Mo - lina): a comparative study. J Exp Mar Biol Ecol 426-427: 18−27 Lagos NA, Benítez S, Duarte C, Lardies MA and others (2016) Effects of temperature and ocean acidification on shell characteristics of Argopecten purpuratus: implica-tions for scallop aquaculture in an upwelling-influenced area. Aquacult Environ Interact 8: 357−370 Lardies MA, Arias MB, Poupin MJ, Manríquez PH and oth-ers (2014) Differential response to ocean acidification in physiological traits of Concholepas concholepas popula-tions. J Sea Res 90: 127−134 Lardies MA, Benítez S, Osores S, Vargas CA, Duarte C, Lohrmann KB, Lagos NA (2017) Physiological and histo - pathological impacts of increased carbon dioxide and temperature on the scallops Argopecten purpuratus cultured under upwelling influences in northern Chile. Aquaculture 479: 455−466 Lemasson AJ, Fletcher S, Hall-Spencer JM, Knights AM (2017) Linking the biological impacts of ocean acidifica-tion on oysters to changes in ecosystem services: a review. J Exp Mar Biol Ecol 492: 49−62 Mackenzie CL, Ormondroyd GA, Curling SF, Ball RJ, Whitely NM, Malham SK (2014) Ocean warming, more than acidification, reduces shell strength in a commercial shellfish species during food limitation. PLOS ONE 9: e86764 McElhany P (2017) CO2 sensitivity experiments are not suf-ficient to show an effect of ocean acidification. ICES J Mar Sci 74: 926−928 Mehrbach C, Culberson CH, Hawley JE, Pytkowicz RM (1973) Measurement of the apparent dissociation con-stants of carbonic acid in seawater at atmospheric pres-sure. Limnol Oceanogr 18: 897−907 Melzner F, Thomsen J, Koeve W, Oschlies A and others (2013) Future ocean acidification will be amplified by hypoxia in coastal habitats. Mar Biol 160: 1875−1888 Michaelidis B, Ouzounis C, Paleras A, Pörtner HO (2005) Effects of long-term moderate hypercapnia on acid−base balance and growth rate in marine mussels Mytilus gal-loprovincialis. Mar Ecol Prog Ser 293: 109−118 Miller AW, Reynolds AC, Sobrino C, Riedel GF (2009) Shell-fish face uncertain future in high CO2 world: influence of acidification on oyster larvae calcification and growth in estuaries. PLOS ONE 4: e5661 Navarro JM (1988) The effects of salinity on the physio - logical ecology of Choromytilus chorus (Molina, 1782) (Bivalvia: Mytilidae). J Exp Mar Biol Ecol 122: 19−33 Navarro JM, Torres R, Acuña K, Duarte C and others (2013) Impact of medium-term exposure to elevated pCO2 lev-els on the physiological energetics of the mussel Mytilus chilensis. Chemosphere 90: 1242−1248 Navarro JM, Duarte C, Manríquez PH, Lardies MA and oth-ers (2016) Ocean warming and elevated carbon dioxide: multiple stressor impacts on juvenile mussels from south-ern Chile. ICES J Mar Sci 73: 764−771 Nienhuis S, Palmer AR, Harley CD (2010) Elevated CO2 affects shell dissolution rate but not calcification rate in a marine snail. Proc R Soc B 277: 2553−2558 Orr JC, Fabry VJ, Aumont O, Bopp L and others (2005) Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437: 681−686 Osores SJ, Lagos NA, San Martin V, Manríquez PH and others (2017) Plasticity and inter-population variability in physiological and life-history traits of the mussel Mytilus chilensis: a reciprocal transplant experiment. J Exp Mar Biol Ecol 490: 1−12 Palmer AR (1982) Growth in marine gastropods: a non-destructive technique for independently measuring shell and body weight. Malacologia 23: 63−73 Parker LM, Ross PM, O’Connor WA, Borysko L, Raftos DA, Pörtner HO (2012) Adult exposure influences offspring response to ocean acidification in oysters. Glob Change Biol 18: 82−92 Pierrot D, Lewis E, Wallace DWR (2006) MS Excel program developed for CO2 system calculations. ORNL/CDIAC-105a. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, TN Ramajo L, Marba N, Prado L, Peron S and others (2016) Bio-mineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification. Glob Change Biol 22: 2025−2037 Range P, Chícharo MA, Ben-Hamadou R, Piló D and others (2014) Impacts of CO2-induced seawater acidification on coastal Mediterranean bivalves and interactions with other climatic stressors. Reg Environ Change 14(Suppl 1): 19−30 Sabine C, Feely RA, Gruber N, Key RM and others (2004) The oceanic sink of anthropogenic CO2. Science 305: 367–371 SERNAPESCA (Servicio Nacional de Pesca y Acuicultura) (2014) Anuarios estadísticos del Servicio Nacional de Pesca y Acuicultura. www.sernapesca.cl Solórzano L (1969) Determination of ammonia in natural waters by the phenolhypochlorite method. Limnol Oce - anogr 14: 799−801 Thomsen J, Melzner F (2010) Moderate seawater acidifica-tion does not elicit long-term metabolic depression in the blue mussel Mytilus edulis. Mar Biol 157: 2667−2676 Thomsen J, Casties I, Pansch C, Körtzinger A, Melzner F (2013) Food availability outweighs ocean acidification effects in juvenile Mytilus edulis: laboratory and field experiments. Glob Change Biol 19: 1017−1027 Thomsen J, Stapp LS, Haynert K, Schade H, Danelli M, Lannig G, Melzner F (2017) Naturally acidified habitat selects for ocean acidification-tolerant mussels. Sci Adv 3: e1602411 Toro B, Navarro JM, Palma-Fleming H (2003) Relationship between bioenergetics responses and organic pollutants in the giant mussel, Choromytilus chorus (Mollusca: Mytilidae). Aquat Toxicol 63: 257−269 Torres R, Pantoja S, Harada N, González HE, Daneri G, Frangopulos M, Fukasawa M (2011) Air-sea CO2 fluxes along the coast of Chile: from CO2 outgassing in central northern upwelling waters to CO2 uptake in southern Patagonian fjords. J Geophys Res 116: C09006 Torres R, Manriquez PH, Duarte C, Navarro JM, Lagos NA, Vargas CA, Lardies MA (2013) Evaluation of a semi - automatic system for long-term seawater carbonate chemistry manipulation. Rev Chil Hist Nat 86: 443−451 Vargas CA, Aguilera V, Martín V, Manríquez P and others (2015) CO2-driven ocean acidification disrupts the filter feeding behavior in Chilean gastropod and bivalve spe-cies from different geographic localities. Estuaries Coasts 38: 1163−1177 Vargas CA, Lagos NA, Lardies MA, Duarte C and others (2017) Species-specific responses to ocean acidification should account for local adaptation and adaptive plasti-city. Nature Ecol Evol 1: 0084 Vargas CA, Cuevas LA, Silva N, Gonzalez HE, Pol-Holz D, Narvaez DA (2018) Influence of glacier melting and river discharges on the nutrient distribution and DIC recycling in the southern Chilean Patagonia. J Geophys Res Bio-geosci 123: 256−270 Velasco LA, Navarro JM (2003) Energetic balance of infau-nal (Mulinia edulis King, 1831) and epifaunal (Mytilus chilensis Hupé, 1854) bivalves in response to wide varia-tions in concentration and quality of seston. J Exp Mar Biol Ecol 296: 79−92 Vihtakari M, Hendriks IE, Holding J, Renaud PE, Duarte CM, Havenhand JN (2013) Effects of ocean acidification and warming on sperm activity and early life stages of the Mediterranean mussel (Mytilus galloprovincialis). Water 5: 1890−1915 Wang Y, Li L, Hu M, Lu W (2015) Physiological energetic of the thick shell mussel Mytilus coruscus exposed to sea-water acidification and thermal stress. Sci Total Environ 514: 261−272 White MM, McCorkle DC, Mullineaux LS, Cohen AL (2013)Benthic habitats such as intertidal areas, sandy or rocky shores, upwelling zones, and estuaries are characterized by variable environmental conditions. This high variability of environmental stressors such as temperature, salinity, and pH/pCO 2 levels have been shown to impose restrictions on organismal performance. The giant mussel Choromytilus chorus forms intertidal and subtidal mussel beds in estuarine zones associated with fjords occurring in southern Chile and is an important aquacultural resource in Patagonia. In this study, we estimated the sensitivity of physiological traits and energy balance of C. chorus juveniles exposed to 3 pCO 2 treatments (500, 750, and 1200 μatm) for 30 d. Results showed that in acidified, high pCO 2 conditions, C. chorus juveniles had increased metabolic rates; however, other physiological traits (clearance and ingestion rates, ammonia excretion, absorption efficiency, growth rate, biomass production, net calcification, and dissolution rates) were not affected. These results suggest that when subjected to acidification, the adaptive response of C. chorus triggers tradeoffs among physiological traits that favor sustained feeding and growth in order to combat increased metabolic stress. As has been reported for other marine organisms, chronic exposure to variable pH/pCO 2 in their native habitats, such as estuarine zones, could explain the differential acclimatization capacity of giant mussels to cope with the increase in pCO 2 . Additionally, the fact that the mussels did not suffer from mortality indicates that increased pCO 2 levels may have chronic, but not lethal, effects on this species under these experimental conditions. © The authors 2017.https://www.int-res.com/abstracts/aei/v10/p267-278

Confinement of neutral fermions by a pseudoscalar double-step potential in (1+1) dimensions

The problem of confinement of neutral fermions in two-dimensional space-time is approached with a pseudoscalar double-step potential in the Dirac equation. Bound-state solutions are obtained when the coupling is of sufficient intensity. The confinement is made plausible by arguments based on effective mass and anomalous magnetic interaction.Comment: 8 pages, 1 figur

Expectations in Micro Data: Rationality Revisited

An increasing number of longitudinal data sets collect expectations information regarding a variety of future individual level events and decisions, providing researchers with the opportunity to explore expectations over micro variables in detail. We provide a theoretical framework and an econometric methodology to use that type of information to test the Rational Expectations hypothesis in models of individual behavior, and present tests using two different panel data sets.

North American Community Service Pilot Project

North American Community Service Pilot Projec

Spin precession and spin Hall effect in monolayer graphene/Pt nanostructures

Spin Hall effects have surged as promising phenomena for spin logics operations without ferromagnets. However, the magnitude of the detected electric signals at room temperature in metallic systems has been so far underwhelming. Here, we demonstrate a two-order of magnitude enhancement of the signal in monolayer graphene/Pt devices when compared to their fully metallic counterparts. The enhancement stems in part from efficient spin injection and the large resistivity of graphene but we also observe 100% spin absorption in Pt and find an unusually large effective spin Hall angle of up to 0.15. The large spin-to-charge conversion allows us to characterise spin precession in graphene under the presence of a magnetic field. Furthermore, by developing an analytical model based on the 1D diffusive spin-transport, we demonstrate that the effective spin-relaxation time in graphene can be accurately determined using the (inverse) spin Hall effect as a means of detection. This is a necessary step to gather full understanding of the consequences of spin absorption in spin Hall devices, which is known to suppress effective spin lifetimes in both metallic and graphene systems.Comment: 14 pages, 6 figures. Accepted in 2D Materials. https://doi.org/10.1088/2053-1583/aa882