Optimal Taxation With Heterogeneous Firms

We study steady state optimal taxation in a context where firms differ in productivity and they decide whether to produce or not after comparing after-tax profits vis-à-vis an outside alternative option. The government taxes capital income, firms’ profits and labor income, but does not tax the alternative outside option. In this context, taxation might distort the firms’ decisions to participate in production (extensive margin) as well as their factor allocations once they decide to produce (intensive margin). We find that the government has incentives to subsidize costs to induce firms into production. The optimal capital income tax is negative while the corporate tax rate is positive and the sign of labor income tax is ambiguous.

Measuring Dislocation Density in Aluminum with Resonant Ultrasound Spectroscopy

Dislocations in a material will, when present in enough numbers, change the speed of propagation of elastic waves. Consequently, two material samples, differing only in dislocation density, will have different elastic constants, a quantity that can be measured using Resonant Ultrasound Spectroscopy. Measurements of this effect on aluminum samples are reported. They compare well with the predictions of the theory.Comment: 4 pages, 2 figure

Straw mulch as a sustainable solution to decrease runoff and erosion in glyphosate-treated clementine plantations in Eastern Spain. An assessment using rainfall simulation experiments

[EN] In many Mediterranean areas, citrus orchards exhibit high soil loss rates because of the expansion of drip irrigation that allows cultivation on sloping terrain and the widespread use of glyphosate. To mitigate these non-sustainable soil losses, straw mulch could be applied as an efficient solution but this has been poorly studied. Therefore, the main goal of this paper was to assess the use of straw mulch as a tool to reduce soil losses in clementine plantations, which can be considered representative of a typical Mediterranean citrus orchard. A total of 40 rainfall simulation experiments were carried out on 20 pairs of neighbouring bare and mulched plots. Each experiment involved applying 38.8 mm of rain at a constant rate over 1 h to a circular plot of 0.28 m(2) circular plots. The results showed that a cover of 50% of straw (60 g m(-2)) was able to delay the time to ponding from 32 to 52 s and the time to runoff initiation from 57 to 129 s. Also, the mulching reduced the runoff coefficient from 65.6 to 50.5%. The effect on sediment transport was even more pronounced, as the straw mulch reduced the sediment concentration from 16.7 g l(-1) to 3.6 g l(-1) and the soil erosion rates from 439 g to 73 g. Our results indicated that mulching can be used as a useful management practice to control soil erosion rates due to the immediate effect on high soil detachment rate and runoff initiation reduction in conventional clementine orchards on sloping land, by slowing down runoff initiation and by reducing runoff generation and, especially, sediment losses. We indirectly concluded that straw mulch is also a sustainable solution in glyphosate-treated citrus plantations.This paper is part of the results of research projects GL2008-02879/BTE, LEDDRA 243857 and RECARE-FP7 (ENV.2013.6.2-4).Keesstra, S.; Rodrigo-Comino, J.; Novara, A.; Giménez Morera, A.; Pulido, M.; Di Prima, S.; Cerda, A. (2019). Straw mulch as a sustainable solution to decrease runoff and erosion in glyphosate-treated clementine plantations in Eastern Spain. An assessment using rainfall simulation experiments. CATENA. 174:95-103. https://doi.org/10.1016/j.catena.2018.11.007S9510317

Loop assembly: a simple and open system for recursive fabrication of DNA circuits.

High efficiency methods for DNA assembly have enabled routine assembly of synthetic DNAs of increased size and complexity. However, these techniques require customisation, elaborate vector sets or serial manipulations for the different stages of assembly. We have developed Loop assembly based on a recursive approach to DNA fabrication. The system makes use of two Type IIS restriction endonucleases and corresponding vector sets for efficient and parallel assembly of large DNA circuits. Standardised level 0 parts can be assembled into circuits containing 1, 4, 16 or more genes by looping between the two vector sets. The vectors also contain modular sites for hybrid assembly using sequence overlap methods. Loop assembly enables efficient and versatile DNA fabrication for plant transformation. We show construction of plasmids up to 16 genes and 38 Kb with high efficiency (>80%). We have characterized Loop assembly on over 200 different DNA constructs and validated the fidelity of the method by high-throughput Illumina plasmid sequencing. Our method provides a simple generalised solution for DNA construction with standardised parts. The cloning system is provided under an OpenMTA license for unrestricted sharing and open access. This article is protected by copyright. All rights reserved.Support for the authors was provided by Becas Chile and the Cambridge Trust (to B.P.), University of Cambridge BBSRC DTP programme (to M.D.), and the Biotechnology and Biological Sciences Research Council and Engineering and Physical Sciences Research Council [OpenPlant Grant No. BB/L014130/1] (to N.P., F.F. and J.H.). Laboratory automation, nextgeneration sequencing and library construction was delivered via the BBSRC National Capability in Genomics (BB/CCG1720/1) at Earlham Institute. F.F. acknowledges funding from CONICYT Fondecyt Iniciación 11140776. F.F. and R.A.G. acknowledge funding from Fondo de Desarrollo de Areas Prioritarias (FONDAP) Center for Genome Regulation (15090007) and Millennium Nucleus Center for Plant Systems and Synthetic Biology (NC130030)

Gregariousness in the giant sloth Lestodon (Xenarthra): multi-proxy approach of a bonebed from the Last Maximum Glacial of Argentine Pampas

Megamammals constituted an important component in the Pleistocene faunal communities of South America. Paleobiological and paleoecological studies involving different megamammal taxa have increased significantly in the last years, but there are still several poorly-known issues of its life history. In this work, we analyze an assemblage composed of 13 individuals of different ontogenetic stages, and possibly different sex, belonging to the giant ground sloth Lestodon armatus (Xenarthra, Folivora), recovered from Playa del Barco site (Pampean Region, Argentina). A dating of 19,849 years Cal BP allows assigning this assemblage to a period of the MIS (Marine Isotope Stage) 2 related to the end of the Last Glacial Maximum. Based on multiple lines of research (e.g. taphonomy, paleopathology, osteohistology, isotopy), we interpret the origin of the assemblage and diverse paleobiological and paleoecological aspects (e.g. social behavior, ontogenetic changes, sexual dimorphism, diseases, resource and habitat use, trophic relationships) of L. armatus. Evidence suggests that the assemblage was formed by a local single event of catastrophic mortality, which affected different members of a social group. This record represents the first accurate evidence of gregariousness for this ground sloth, providing new data on a poorly-known behavior among extinct Folivora

Tillage versus no-tillage. soil properties and hydrology in an organic persimmon farm in eastern Iberian Peninsula

There is an urgent need to implement environmentally friendly agriculture management practices to achieve the Sustainable Goals for Development (SDGs) of the United Nations by 2030. Mediterranean agriculture is characterized by intense and millennia-old tillage management and as a consequence degraded soil. No-Tillage has been widely examined as a solution for soil degradation but No-Tillage relies more on the application of herbicides that reduce plant cover, which in turn enhances soil erosion. However, No-Tillage with weed cover should be researched to promote organic farming and sustainable agriculture. Therefore, we compare Tillage against No-Tillage using weed cover as an alternative strategy to reduce soil losses in persimmon plantations, both of them under organic farming management. To achieve these goals, two plots were established at "La Canyadeta" experimental station on 25-years old Persimmon plantations, which are managed with Tillage and No-Tillage for 3 years. A survey of the soil cover, soil properties, runoff generation and initial soil losses using rainfall simulation experiments at 55 mm h-1 in 0.25 m2 plot was carried out. Soils under Tillage are bare (96.7%) in comparison to the No-Tillage (16.17% bare soil), with similar organic matter (1.71 vs. 1.88%) and with lower bulk densities (1.23 vs. 1.37 g cm3). Tillage induces faster ponding (60 vs. 92 s), runoff (90 vs. 320 s) and runoff outlet (200 vs. 70 s). The runoff discharge was 5.57 times higher in the Tillage plots, 8.64 for sediment concentration and 48.4 for soil losses. We conclude that No-tillage shifted the fate of the tilled field after 3 years with the use of weeds as a soil cover conservation strategy. This immediate effect of No-Tillage under organic farming conditions is very promising to achieve the SDGs

One of the closest exoplanet pairs to the 3:2 Mean Motion Resonance: K2-19b \& c

The K2 mission has recently begun to discover new and diverse planetary systems. In December 2014 Campaign 1 data from the mission was released, providing high-precision photometry for ~22000 objects over an 80 day timespan. We searched these data with the aim of detecting further important new objects. Our search through two separate pipelines led to the independent discovery of K2-19b \& c, a two-planet system of Neptune sized objects (4.2 and 7.2 $R_\oplus$), orbiting a K dwarf extremely close to the 3:2 mean motion resonance. The two planets each show transits, sometimes simultaneously due to their proximity to resonance and alignment of conjunctions. We obtain further ground based photometry of the larger planet with the NITES telescope, demonstrating the presence of large transit timing variations (TTVs), and use the observed TTVs to place mass constraints on the transiting objects under the hypothesis that the objects are near but not in resonance. We then statistically validate the planets through the \texttt{PASTIS} tool, independently of the TTV analysis.Comment: 18 pages, 10 figures, accepted to A&A, updated to match published versio

Prenatal Transmission of Syphilis and Human Immunodeficiency Virus in Brazil: Achieving Regional Targets for Elimination

Background. The Pan-American Health Organization has called for reducing (1) human immunodeficiency virus (HIV) mother-to-child transmission (MTCT) to ≤0.30 infections/1000 live births (LB), (2) HIV MTCT risk to ≤2.0%, and (3) congenital syphilis (CS) incidence to ≤0.50/1000 LB in the Americas by 2015. Methods. Using published Brazilian data in a mathematical model, we simulated a cohort of pregnant women from antenatal care (ANC) through birth. We investigated 2 scenarios: “current access” (89.1% receive one ANC syphilis test and 41.1% receive 2; 81.7% receive one ANC HIV test and 18.9% receive birth testing; if diagnosed, 81.0% are treated for syphilis and 87.5% are treated for HIV) and “ideal access” (95% of women undergo 2 HIV and syphilis screenings; 95% receive appropriate treatment). We conducted univariate and multivariate sensitivity analyses on key inputs. Results. With current access, we projected 2.95 CS cases/1000 LB, 0.29 HIV infections/1000 LB, 7.1% HIV MTCT risk, and 11.11 intrauterine fetal demises (IUFD)/1000 pregnancies, with significant regional variation. With ideal access, we projected improved outcomes: 1.00 CS cases/1000 LB, 0.10 HIV infections/1000 LB, HIV MTCT risk of 2.4%, and 10.65 IUFD/1000 pregnancies. Increased testing drove the greatest improvements. Even with ideal access, only HIV infections/1000 LB met elimination goals. Achieving all targets required testing and treatment >95% and reductions in prevalence and incidence of HIV and syphilis. Conclusions. Increasing access to care and HIV and syphilis antenatal testing will substantially reduce HIV and syphilis MTCT in Brazil. In addition, regionally tailored interventions reducing syphilis incidence and prevalence and supporting HIV treatment adherence are necessary to completely meet elimination goals

Evidence‐based treatment for gynoid lipodystrophy: A review of the recent literature

Resumen La lipodistrofia ginoide (LDG) es una alteracion estructural, inflamatoria y bioquımica del tejido subcutaneo que causa modificaciones topograficas en la piel. Conocida comunmente como “celulitis”, la LDG afecta hasta a 90% de las mujeres, practicamente en todas las etapas de la vida, iniciando en la pubertad. Se trata de una condicion que afecta considerablemente la calidad de vida de quien la padece. Es motivo frecuente de consulta aunque las pacientes recurren a tratamientos empıricos, improvisados, sin bases ni evidencia cientıfica, los cuales desmotivan y producen frustracion no solo por su falta de resultados, sino por complicaciones derivadas de dichos tratamientos. Un grupo de expertos de diversas especialidades involucradas en el manejo de este problema presenta en este artıculo el resultado de una busqueda bibliografica sistematica y de la discusion consensuada de la evidencia obtenida de diversos tratamientos disponibles actualmente. El analisis se dividio en tratamientos topicos, tratamientos sistemicos, tratamientos no invasivos y tratamientos mınimamente invasivos