A new method to find the potential center of N-body systems

We present a new and fast method to nd the potential center of an N-body distribution. The method uses an iterative algorithm which exploits the fact that the gradient of the potential is null at its center: it uses a smoothing radius to avoid getting trapped in secondary minima. We have tested this method on several random realizations of King models (in which the numerical computation of this center is rather dicult, due to the constant density within their cores), and com- pared its performance and accuracy against a more straightforward, but computer intensive method, based on cartesian meshes of increasing spatial resolution. In all cases, both methods converged to the same center, within the mesh resolution, but the new method is two orders of magnitude faster. We have also tested the method with one astronomical problem: the evolu- tion of a 105 particle King model orbiting around a xed potential that represents our Galaxy. We used a spherical harmonics expansion N-body code, in which the potential center determination is crucial for the correct force computation. We compared this simulation with another one in which a method previously used to determine the expansion center is employed (White 1983). Our routine gives better results in energy conservation and mass loss.Fil: Aguilar, L. A.. Universidad Nacional Autonoma de Mexico. Instituto de Astronomia; MéxicoFil: Cruz, F.. Universidad Nacional Autonoma de Mexico. Instituto de Astronomia; MéxicoFil: Carpintero, Daniel Diego. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

A new method to find the potential center of <i>N</i>-body systems

We present a new and fast method to nd the potential center of an N-body distribution. The method uses an iterative algorithm which exploits the fact that the gradient of the potential is null at its center: it uses a smoothing radius to avoid getting trapped in secondary minima. We have tested this method on several random realizations of King models (in which the numerical computation of this center is rather dicult, due to the constant density within their cores), and compared its performance and accuracy against a more straightforward, but computer intensive method, based on cartesian meshes of increasing spatial resolution. In all cases, both methods converged to the same center, within the mesh resolution, but the new method is two orders of magnitude faster. We have also tested the method with one astronomical problem: the evolution of a 105 particle King model orbiting around a xed potential that represents our Galaxy. We used a spherical harmonics expansion N-body code, in which the potential center determination is crucial for the correct force computation. We compared this simulation with another one in which a method previously used to determine the expansion center is employed (White 1983). Our routine gives better results in energy conservation and mass loss.Se presenta un método rápido para encontrar el centro del potencial de una distribución de N-cuerpos. El método usa un algoritmo iterativo que aprovecha el hecho de que el gradiente del potencial es nulo en su centro; emplea asimismo un radio de suavizado para evitar quedar atrapado en mínimos locales. Se ha probado el método con modelos de King (cuyos núcleos, de densidad relativamente constante, hacen particularmente difícil la determinación numérica de este centro), y se ha comparado su eficiencia y precisión con un método más directo, aunque de cálculo intensivo, basado en mallas cartesianas de resolución espacial creciente. En todos los casos, ambos métodos convergen al mismo centro dentro de la resolución de la malla, aunque el método iterativo es dos órdenes de magnitud más rápido. Utilizamos este método en un problema astronómico: la evolución de un modelo de King de 105 partículas, en órbita alrededor de un potencial fijo representativo de nuestra Galaxia. Se utilizó un código de N-cuerpos con expansión en armónicos esféricos, en el que la determinación del centro del potencial es esencial para un cálculo correcto de las fuerzas. Se comparó esta simulación con el mismo código pero con un método empleado anteriormente para determinar el centro de expansión (White 1983). Con nuestra rutina se obtienen mejores resultados en la conservación de energía y de la masa.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

A new method to find the potential center of <i>N</i>-body systems

We present a new and fast method to nd the potential center of an N-body distribution. The method uses an iterative algorithm which exploits the fact that the gradient of the potential is null at its center: it uses a smoothing radius to avoid getting trapped in secondary minima. We have tested this method on several random realizations of King models (in which the numerical computation of this center is rather dicult, due to the constant density within their cores), and compared its performance and accuracy against a more straightforward, but computer intensive method, based on cartesian meshes of increasing spatial resolution. In all cases, both methods converged to the same center, within the mesh resolution, but the new method is two orders of magnitude faster. We have also tested the method with one astronomical problem: the evolution of a 105 particle King model orbiting around a xed potential that represents our Galaxy. We used a spherical harmonics expansion N-body code, in which the potential center determination is crucial for the correct force computation. We compared this simulation with another one in which a method previously used to determine the expansion center is employed (White 1983). Our routine gives better results in energy conservation and mass loss.Se presenta un método rápido para encontrar el centro del potencial de una distribución de N-cuerpos. El método usa un algoritmo iterativo que aprovecha el hecho de que el gradiente del potencial es nulo en su centro; emplea asimismo un radio de suavizado para evitar quedar atrapado en mínimos locales. Se ha probado el método con modelos de King (cuyos núcleos, de densidad relativamente constante, hacen particularmente difícil la determinación numérica de este centro), y se ha comparado su eficiencia y precisión con un método más directo, aunque de cálculo intensivo, basado en mallas cartesianas de resolución espacial creciente. En todos los casos, ambos métodos convergen al mismo centro dentro de la resolución de la malla, aunque el método iterativo es dos órdenes de magnitud más rápido. Utilizamos este método en un problema astronómico: la evolución de un modelo de King de 105 partículas, en órbita alrededor de un potencial fijo representativo de nuestra Galaxia. Se utilizó un código de N-cuerpos con expansión en armónicos esféricos, en el que la determinación del centro del potencial es esencial para un cálculo correcto de las fuerzas. Se comparó esta simulación con el mismo código pero con un método empleado anteriormente para determinar el centro de expansión (White 1983). Con nuestra rutina se obtienen mejores resultados en la conservación de energía y de la masa.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

A new method to find the potential center of <i>N</i>-body systems

We present a new and fast method to nd the potential center of an N-body distribution. The method uses an iterative algorithm which exploits the fact that the gradient of the potential is null at its center: it uses a smoothing radius to avoid getting trapped in secondary minima. We have tested this method on several random realizations of King models (in which the numerical computation of this center is rather dicult, due to the constant density within their cores), and compared its performance and accuracy against a more straightforward, but computer intensive method, based on cartesian meshes of increasing spatial resolution. In all cases, both methods converged to the same center, within the mesh resolution, but the new method is two orders of magnitude faster. We have also tested the method with one astronomical problem: the evolution of a 105 particle King model orbiting around a xed potential that represents our Galaxy. We used a spherical harmonics expansion N-body code, in which the potential center determination is crucial for the correct force computation. We compared this simulation with another one in which a method previously used to determine the expansion center is employed (White 1983). Our routine gives better results in energy conservation and mass loss.Se presenta un método rápido para encontrar el centro del potencial de una distribución de N-cuerpos. El método usa un algoritmo iterativo que aprovecha el hecho de que el gradiente del potencial es nulo en su centro; emplea asimismo un radio de suavizado para evitar quedar atrapado en mínimos locales. Se ha probado el método con modelos de King (cuyos núcleos, de densidad relativamente constante, hacen particularmente difícil la determinación numérica de este centro), y se ha comparado su eficiencia y precisión con un método más directo, aunque de cálculo intensivo, basado en mallas cartesianas de resolución espacial creciente. En todos los casos, ambos métodos convergen al mismo centro dentro de la resolución de la malla, aunque el método iterativo es dos órdenes de magnitud más rápido. Utilizamos este método en un problema astronómico: la evolución de un modelo de King de 105 partículas, en órbita alrededor de un potencial fijo representativo de nuestra Galaxia. Se utilizó un código de N-cuerpos con expansión en armónicos esféricos, en el que la determinación del centro del potencial es esencial para un cálculo correcto de las fuerzas. Se comparó esta simulación con el mismo código pero con un método empleado anteriormente para determinar el centro de expansión (White 1983). Con nuestra rutina se obtienen mejores resultados en la conservación de energía y de la masa.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Survey of the Heteroptera (Insecta: Hemiptera) of the Tandil hills, Buenos Aires province, Argentina

Se presenta un listado de las especies de Heteroptera (Hemiptera: Heteroptera) recolectados y citados que habitan en las sierras de Tandil (Buenos Aires, Argentina). El listado procede de los datos presentes en la literatura y del material procedente de las tareas de muestreo desarrolladas por los autores en sectores serranos cercanos a la ciudad de tandil. Se incluyen 134 especies distribuidas en 31 familias. El registro de Esuris terginus Stål (rhyparochromidae) constituye el primer registro del género y de la especie de la Argentina.Survey of the Heteroptera (Insecta: Hemiptera) of the Tandil hills, Buenos Aires province, Argentina. A list of Heteroptera (Hemiptera: Heteroptera) species from Tandil hills (Buenos Aires, Argentina) is presented. The list gathers bibliographical information as well as material collected by the authors. A number of 134 species are included, distributed in 31 families. Esuris terginus Stål (Rhyparochromidae) constitutes the first record of the genus and the species from Argentina.Facultad de Ciencias Naturales y Muse

Survey of the Heteroptera (Insecta: Hemiptera) of the Tandil hills, Buenos Aires province, Argentina

Se presenta un listado de las especies de Heteroptera (Hemiptera: Heteroptera) recolectados y citados que habitan en las sierras de Tandil (Buenos Aires, Argentina). El listado procede de los datos presentes en la literatura y del material procedente de las tareas de muestreo desarrolladas por los autores en sectores serranos cercanos a la ciudad de tandil. Se incluyen 134 especies distribuidas en 31 familias. El registro de Esuris terginus Stål (rhyparochromidae) constituye el primer registro del género y de la especie de la Argentina.Survey of the Heteroptera (Insecta: Hemiptera) of the Tandil hills, Buenos Aires province, Argentina. A list of Heteroptera (Hemiptera: Heteroptera) species from Tandil hills (Buenos Aires, Argentina) is presented. The list gathers bibliographical information as well as material collected by the authors. A number of 134 species are included, distributed in 31 families. Esuris terginus Stål (Rhyparochromidae) constitutes the first record of the genus and the species from Argentina.Facultad de Ciencias Naturales y Muse

Collecting wild potato species (Solanum sect. Petota) in Peru to enhance genetic representation and fill gaps in ex situ collections

Crop wild relatives (CWRs) are important sources of novel genes, due to their high variability of response to biotic and abiotic stresses, which can be invaluable for crop genetic improvement programs. Recent studies have shown that CWRs are threatened by several factors, including changes in land-use and climate change. A large proportion of CWRs are underrepresented in genebanks, making it necessary to take action to ensure their long-term ex situ conservation. With this aim, 18 targeted collecting trips were conducted during 2017/2018 in the center of origin of potato (Solanum tuberosum L.), targeting 17 diverse ecological regions of Peru. This was the first comprehensive wild potato collection in Peru in at least 20 years and encompassed most of the unique habitats of potato CWRs in the country. A total of 322 wild potato accessions were collected as seed, tubers, and whole plants for ex situ storage and conservation. They belonged to 36 wild potato species including one accession of S. ayacuchense that was not conserved previously in any genebank. Most accessions required regeneration in the greenhouse prior to long-term conservation as seed. The collected accessions help reduce genetic gaps in ex situ conserved germplasm and will allow further research questions on potato genetic improvement and conservation strategies to be addressed. These potato CWRs are available by request for research, training, and breeding purposes under the terms of the International Treaty for Plant Genetic Resources for Food and Agriculture (ITPGRFA) from the Instituto Nacional de Innovacion Agraria (INIA) and the International Potato Center (CIP) in Lima-Peru

PYL1- and PYL8-like ABA Receptors of Nicotiana benthamiana Play a Key Role in ABA Response in Seed and Vegetative Tissue

19 pags., 7 figs., 3 tabs. -- This article belongs to the Special Issue Drought and Heat Stress Signalling Responses in PlantsTo face the challenges of climate change and sustainable food production, it is essential to develop crop genome editing techniques to pinpoint key genes involved in abiotic stress signaling. The identification of those prevailing abscisic acid (ABA) receptors that mediate plant-environment interactions is quite challenging in polyploid plants because of the high number of genes in the PYR/PYL/RCAR ABA receptor family. Nicotiana benthamiana is a biotechnological crop amenable to genome editing, and given the importance of ABA signaling in coping with drought stress, we initiated the analysis of its 23-member family of ABA receptors through multiplex CRISPR/Cas9-mediated editing. We generated several high-order mutants impaired in NbPYL1-like and NbPYL8-like receptors, which showed certain insensitivity to ABA for inhibition of seedling establishment, growth, and development of shoot and lateral roots as well as reduced sensitivity to the PYL1-agonist cyanabactin (CB). However, in these high-order mutants, regulation of transpiration was not affected and was responsive to ABA treatment. This reveals a robust and redundant control of transpiration in this allotetraploid plant that probably reflects its origin from the extreme habitat of central Australia.This research was supported by grant PID2020-113100RB (P.L.R.) and PID2020-119805RB (A.A.) funded by MCIN/AEI/10.13039/501100011033 and by Newcotiana H2020 760331 (D.O.).Peer reviewe

Adapting Agriculture to Climate Change: A Synopsis of Coordinated National Crop Wild Relative Seed Collecting Programs across Five Continents

The Adapting Agriculture to Climate Change Project set out to improve the diversity, quantity, and accessibility of germplasm collections of crop wild relatives (CWR). Between 2013 and 2018, partners in 25 countries, heirs to the globetrotting legacy of Nikolai Vavilov, undertook seed collecting expeditions targeting CWR of 28 crops of global significance for agriculture. Here, we describe the implementation of the 25 national collecting programs and present the key results. A total of 4587 unique seed samples from at least 355 CWR taxa were collected, conserved ex situ, safety duplicated in national and international genebanks, and made available through the Multilateral System (MLS) of the International Treaty on Plant Genetic Resources for Food and Agriculture (Plant Treaty). Collections of CWR were made for all 28 targeted crops. Potato and eggplant were the most collected genepools, although the greatest number of primary genepool collections were made for rice. Overall, alfalfa, Bambara groundnut, grass pea and wheat were the genepools for which targets were best achieved. Several of the newly collected samples have already been used in pre-breeding programs to adapt crops to future challenges.info:eu-repo/semantics/publishedVersio

Coridromius chenopoderis Tatarnic & Cassis, 2008: a new introduced Miridae (Hemiptera: Heteroptera) in Chilean fauna

The presence in South America of the Australian species Coridromius chenopoderis Tatarnic & Cassis, 2008 is here reported for the first time in Chile from Copiapó (Provincia de Copiapó), Región de Atacama (UTM, Datum WGS 84, East 356696, North 6979721, HUSO 19). This is the first species of the tribe Halticini in Chile. Diagnostic characters, figures, antecedents of introduced species in this country as well as a complete bibliography are here given.Se informa sobre la presencia en América del Sur de la especie australiana Coridromius chenopoderis Tatarnic & Cassis de 2008 aquí por primera vez para Chile, en Copiapó (Provincia de Copiapó), Región de Atacama (UTM, Datum WGS 84, Este 356696, Norte 6979721 , HUSO 19). Esta es la primera especie de la tribu Halticini en Chile. Se ofrecen los caracteres diagnósticos, fotos, antecedentes de las especies introducidas en este país, así como una bibliografía completa