A New Species of Placida (Gastropoda: Sacoglossa) from Southern South America Cetra, Nicolás; Gutierrez Gregoric, Diego Eduardo; Roche, María Andrea de Las Mercedes Heterobranch sea slugs exhibit a wide range of body shapes, sizes and color patterns. The genus Placida (Sacoglossa) includes cryptic species, and in 2019 four species were recovered through molecular studies. Specimens of Placida collected in the Argentinian Sea (San Matias Gulf, Patagonia) between 2016 and 2019 are shown to belong to an undescribed species using molecular and morphological evidence. Placida sudamericana n. sp. is described using external, radular, penial stylet and egg mass characters. The specimens were always found associated with the green algae Codium fragile. Placida sudamericana is the only Placida species in the South Atlantic waters of South America and was recorded in a molluscan biodiversity hotspot.

Metaforización y elaboración de una experiencia traumática a través de la DMT Manrique, Maria Soledad El trabajo parte de una serie de preguntas que surgen de una experiencia como danza movimiento terapeuta en un taller de tres meses de duración en la ciudad de Buenos Aires. Hace foco en el proceso de una de las participantes del taller y busca dar cuenta de él respondiendo a las preguntas surgidas. ¿Qué es lo que se trasforma en este proceso? ¿Cómo se transforma? y ¿Cuál es la función de la danza movimiento terapeuta y del vínculo entre ambas en el proceso? Desde un marco epistemológico que define los fenómenos como campos problemáticos complejos y situándonos en el enfoque clínico se realizó un análisis inductivo de los doce encuentros del taller enfocando en el caso seleccionado. La teoría psicoanalítica y estudios previos en Danza Movimiento Terapia (DMT) aportaron conceptos clave para elaborar hipótesis que dan cuenta del proceso. Permiten comprender cómo el pasaje de lo no verbal a lo verbal vía la metaforización que hablitan la danza y el arte plástico, contribuye con la elaboración de una experiencia traumática. Se describen algunas experiencias en DMT que parecen haber contribuido al proceso, entre ellas, un modo de intervención no descripto en la bibliografía que denominamos complementación.; The work is based on a series of questions that arise from an experience as a dance movement therapist in a threemonth workshop in Buenos Aires. It focuses on the process of one of the workshop participants and seeks to account for it by answering the questions: What is it that transforms in this process? How does it transform? And what is the role of dance movement therapist and the link between the participant and the dance movement therapist in the process? From an epistemological framework that defines the phenomena as complex problematic fields and from the clinical perspective, an inductive analysis of the eleven meetings of the workshop was carried out, focusing on the selected case. Psychoanalytic theory and previous studies in DMT contributed key concepts to elaborate hypotheses that account for the process. They allow us to understand how the passage from the non-verbal to the verbal via the metaphorization that dance and plastic art inhabit, contributes to the elaboration of a traumatic experience. Some experiences in DMT are described that seem to have contributed in the process, among them, a mode of intervention not described in the bibliography that we call complementation.

Sobre La intérprete Brignone, Germán Pablo La conformación de una poética -y una metapoética- que definan la obra de un autor a través del tiempo implica tener en cuenta los cambios ocurridos en los enfoques temáticos predominantes, según los momentos de su producción. En el caso de Mayorga, que en sus primeras obras mostraba un claro predominio de la memoria como eje vertebral de su dramaturgia, en sus textos más recientes, se puede observar un desplazamiento hacia las formas metateatrales, una clara intención de asumir la misión del teatro mediante diversas formas de auto-reflexión, de un permanente volver sobre símismo, para presentar una imagen del mundo que abra los ojos del espectador frente a lo que se le oculta. Ya sea a través de la reflexión directa sobre nuestra percepción de la realidad (Intensamente azules, 2018), como de la exposición satírica de las fábulas que construyen lo cotidiano (Famélica, 2016) o porl as referencias a la “mágica” posibilidad del teatro de cambiar nuestra forma de ver la “verdad de las cosas” (El mago, 2018), los guiños autorreferenciales se suceden con una recurrencia que los convierten tanto en el recurso como en el tema más utilizado por el autor.

Emotions for Virtual Learning Environments Aballay, Laura Nidia; Aciar, Silvana Vanesa; Collazo, Cesar Emotions are present and influence the learning process. One of the current challenges is how to get the emotions experienced by learners. Numerous mechanisms have been developed for this purpose. These mechanisms assess a number of basic emotions provided by the literature. A Virtual Learning Environment (VLE), on the other hand, is composed of several functionalities, in which not all emotions experienced by learners are always involved. This article presents a study conducted with experts in affective technologies and education, with the aim of obtaining the emotions that students may feel when using each of the functionalities of a VLE. The study counted with the participation of experts from several Latin American countries and concluded with a list of emotions associated with the functionalities of the VLE. The results obtained will allow the design of future mechanisms for the evaluation of emotions in VLEs, reducing the generic list used in the literature to only those emotions specific to each VLE component.

Microfluidic device based on electrodeposited Nanoporous Gold/Carbon Nanotubes for Plasmodium vivax detection Regiart, Daniel Matias Gaston; Gimenez, Alba Marina; Marques, Rodolfo F.; Soares, Irene S.; Bertotti, Mauro A portable microfluidic electrochemical immunosensor for Plasmodium vivax antibodies determination was developed. A gold microelectrode placed inside the central channel of the microfluidic device was used as immobilization platform for a specific fragment (19-kDa) derived from the P. vivax merozoite surface protein 1, known as PvMSP119. The gold microelectrode surface was modified by using a dynamic hydrogen bubble template (DHBT) method in the presence of multiwalled carbon nanotubes. The synthesized nanocomposite presented exceptional properties, like high specific surface area, remarkable biocompatibility, and excellent electrochemical activity. The material was characterized by scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction, and cyclic voltammetry. The antibodies (anti-PvMSP119) present in the sample bind to the PvMSP119 immobilized on the microelectrode surface, which is then labeled with an anti-IgG antibody marked with horseradish peroxidase (HRP-anti-IgG). Finally, the substrate solution (H2O2 + catechol) is added, and the enzymatic product (quinone) is reduced on the NPAu electrode at +0.2 V (vs. Ag/AgCl). The current obtained is directly proportional to the anti-PvMSP119 concentration in the sample. The detection limit of the microfluidic electrochemical immunosensor was 0.6 ng mL−1, much lower compared to the ELISA detection limit of 15 ng mL−1. This is the first microfluidic electrochemical immunosensor device suitable for point-of-care determination of anti-PvMSP119 in human serum samples.

Social mindfulness and prosociality vary across the globe van Doesum, Niels J.; Murphy, Ryan O.; Gallucci, Marcello; Aharonov Majar, Efrat; Athenstaedt, Ursula; Au, Wing Tung; Bai, Liying; Böhm, Robert; Bovina, Inna; Buchan, Nancy R.; Chen, Xiao Ping; Dumont, Kitty B.; Engelmann, Jan B.; Eriksson, Kimmo; Euh, Hyun; Fiedler, Susann; Friesen, Justin; Gächter, Simon; García, Camilo; González, Roberto; Graf, Sylvie; Growiec, Katarzyna; Guimond, Serge; Hřebíčková, Martina; Immer Bernold, Elizabeth; Joireman, Jeff; Karagonlar, Gokhan; Kawakami, Kerry; Kiyonari, Toko; Kou, Yu; Kuhlman, D. Michael; Kyrtsis, Alexandros Andreas; Lay, Siugmin; Leonardelli, Geoffrey J.; Li, Norman P.; Li, Yang; Maciejovsky, Boris; Manesi, Zoi; Mashuri, Ali; Mok, Aurelia; Moser, Karin S.; Moták, Ladislav; Netedu, Adrian; Pammi, Chandrasekhar; Platow, Michael J.; Raczka Winkler, Karolina; Reinders Folmer, Christopher P.; Reyna, Cecilia; Romano, Angelo; Shalvi, Shaul; Simão, Cláudia; Stivers, Adam W.; Strimling, Pontus; Tsirbas, Yannis; Utz, Sonja; van der Meij, Leander; Waldzus, Sven; Wang, Yiwen; Weber, Bernd; Weisel, Ori; Wildschut, Tim; Winter, Fabian; Wu, Junhui; Yong, Jose C.; van Lange, Paul A.M. Humans are social animals, but not everyone will be mindful of others to the same extent. Individual differences have been found, but would social mindfulness also be shaped by one's location in the world? Expecting cross-national differences to exist, we examined if and how social mindfulness differs across countries. At little to no material cost, social mindfulness typically entails small acts of attention or kindness. Even though fairly common, such low-cost cooperation has received little empirical attention. Measuring social mindfulness across 31 samples from industrialized countries and regions (n = 8,354), we found considerable variation. Among selected country-level variables, greater social mindfulness was most strongly associated with countries' better general performance on environmental protection. Together, our findings contribute to the literature on prosociality by targeting the kind of everyday cooperation that is more focused on communicating benevolence than on providing material benefits.

El impuesto para la educación técnica durante la última dictadura cívico militar Argentina (1976-1983); The tax for technical education during the last Argentine civic-military dictatorship (1976-1983) D'ascanio, Gabriela Andrea En la historiografía de la educación argentina los análisis económicos constituyen un déficit. Este artículo pretende aportar a ese campo de conocimiento a través del estudio del derrotero del Impuesto para la educación técnica durante la última dictadura cívico militar. Se analizan las transformaciones del tributo, que formaba parte de los fondos presupuestados en el Consejo Nacional de Educación Técnica, y los límites que tuvieron las iniciativas de los funcionarios de educación frente a las disposiciones emanadas por el Ministerio de Economía. El análisis de fuentes documentales gubernamentales, legislativas y periodísticas permiten concluir que, las políticas que incidieron en el régimen de financiamiento de la educación técnica, fueron guiadas por intereses económicos y no pedagógicos, y que las contradicciones que existieron en las disposiciones implementadas sólo pueden comprenderse considerando la coyuntura de racionalización del aparato estatal.; In the historiography of Argentine education, economic analyses are a deficit. This article aims to contribute to that field of knowledge through the study of the course of the Tax for technical education during the last civic military dictatorship. In order to do this, we will examine the transformations of the tribute, which was part of the funds budgeted in the National Council of Technical Education (Consejo Nacional de Educación Técnica-CONET), as well as the limits imposed on the initiatives of education officials due to the policies issued by the Ministry of Economy. The interpretation of governmental, legislative and journalistic documentary sources leads to the conclusion that the policies which influenced the financing regime of technical education were guided by economic interests instead of pedagogical ones, and that the contradictions which existed in the implemented provisions can only be understood considering the context of rationalization of the state apparatus.

Particulate systems from maqui (Aristotelia chilensis) wastes to be used as nutraceutics or high value-added ingredients Sette, Paula Andrea; Garrido Makinistian, Francisco Manuel; Maturano, Ramona del Carmen; Salvatori, Daniela Marisol Powdered ingredients from maqui wastes were produced and the effect of drying method (air- and freeze-drying) and particle size on physicochemical and bioactive properties was investigated. Among the particulate systems of smaller particle size that showed the most balanced insoluble to soluble fiber ratio and the best hydration and oil absorption properties, the freeze-dried ones presented the best retention of polyphenols, anthocyanins, and antioxidant capacity. These powders could be used as ingredients in premixes for the development of foods for diabetes or gluten-free diets. The powders of higher granulometry presented excellent flowability and more dispersed particle size distribution, being more adequate for the development of composite foods or nutraceutics.

Copalic Acid: Occurrence, Chemistry, and Biological Activities Gonçalves Medeiros, Vanessa; Duran, Fernando Javier; Lang, Karen Luise (–)-Copalic acid is a naturally occurring labdane‐type diterpene acid usually isolated from oleoresins of Copaifera trees, being considered the biomarker for the genus. This compound has shown many remarkable biological and pharmacological activities, including anti-inflammatory, antimicrobial, antiparasitic, cytotoxic, chemopreventive, antimutagenic, and antigenotoxic activities, which have attracted interest in its use as a prototype for the development of new drugs. This review was organized to describe the extraction, isolation, and analytical methods for quantification and structural elucidation, biological and pharmacological activities, pharmacokinetic and toxicological studies, and several semisynthetic derivatives of copalic acid. Some remaining gaps related to the reviewed activities are also mentioned, while the perspectives for future research with copalic acid are proposed.

Soluble adenylyl cyclase inhibition prevents human sperm functions essential for fertilization Balbach, Melanie; Ghanem, Lubna; Rhossetti, Thomas; Kaur, Navpreet; Ritagliati, Carla; Ferreira, Jacob; Krapf, Dario; Puga Molina, Lis del Carmen; Santi, Celia; Hansen, Jan; Wachten, Dagmar; Fushimi, Makoto; Meinke, Peter; Buck, Jochen; Levin, Lonny Soluble adenylyl cyclase (sAC: ADCY10) has been genetically confirmed to be essential for male fertility in mice and humans. In mice, ex vivo studies of dormant, caudal epididymal sperm demonstrated that sAC is required for initiating capacitation and activating motility. We now use an improved sAC inhibitor, TDI-10229, for a comprehensive analysis of sAC function in mouse and human sperm. In contrast to caudal epididymal mouse sperm, human sperm are collected post-ejaculation, after sAC activity has already been stimulated. In addition to preventing the capacitation-induced stimulation of sAC and protein kinase A activities, tyrosine phosphorylation, alkaliniza- tion, beat frequency and acrosome reaction in dormant mouse sperm, sAC inhibitors interrupt each of these capacitation-induced changes in ejaculated human sperm. Furthermore, we show for the first time that sAC is required during acrosomal exocytosis in mouse and hu- man sperm. These data define sAC inhibitors as candidates for non-hormonal, on-demand contraceptives suitable for delivery via intravagi- nal devices in women.

Exploring the landscape of CHL strings on T d Font, Anamaría; Fraiman, Bernardo; Graña, Mariana; Nuñez, Carmen Alicia; De Freitas, Héctor Parra Compactifications of the heterotic string on special Td/ℤ2 orbifolds realize a landscape of string models with 16 supercharges and a gauge group on the left-moving sector of reduced rank d + 8. The momenta of untwisted and twisted states span a lattice known as the Mikhailov lattice II(d), which is not self-dual for d > 1. By using computer algorithms which exploit the properties of lattice embeddings, we perform a systematic exploration of the moduli space for d ≤ 2, and give a list of maximally enhanced points where the U(1)d+8 enhances to a rank d + 8 non-Abelian gauge group. For d = 1, these groups are simply-laced and simply-connected, and in fact can be obtained from the Dynkin diagram of E10. For d = 2 there are also symplectic and doubly-connected groups. For the latter we find the precise form of their fundamental groups from embeddings of lattices into the dual of II(2). Our results easily generalize to d > 2.

Early-life stress reprograms stress-coping abilities in male and female juvenile rats Pallares, Maria Eugenia; Monteleone, Melisa Carolina; Pastor, Verónica; Grillo Balboa, Jazmín; Alzamendi, Ana; Brocco, Marcela Adriana; Antonelli, Marta Cristina Prenatal stress (PS) is a major risk factor for the development of emotional disorders in adulthood that may be mediated by an altered hypothalamic–pituitary–adrenal axis response to stress. Although the early onset of stress-related disorders is recognized as a major public health problem, to date, there are relatively few studies that have examined the incidence of early-life stressors in younger individuals. In this study, we assessed PS impact on the stress-coping response of juvenile offspring in behavioral tests and in the induced molecular changes in the hippocampus. Furthermore, we assessed if pregnancy stress could be driving changes in patterns of maternal behavior during early lactation. We found that PS modified stress-coping abilities of both sex offspring. In the hippocampus, PS increased the expression of bdnf-IV and crfr1 and induced sex difference changes on glucocorticoids and BDNF mRNA receptor levels. PS changed the hippocampal epigenetic landscape mainly in male offspring. Stress during pregnancy enhanced pup-directed behavior of stressed dams. Our study indicates that exposure to PS, in addition to enhanced maternal behavior, induces dynamic neurobehavioral variations at juvenile ages of the offspring that should be considered adaptive or maladaptive, depending on the characteristics of the confronting environment. Our present results highlight the importance to further explore risk factors that appear early in life that will be important to allow timely prevention strategies to later vulnerability to stress-related disorders.

Universal critical exponents of the magnetic domain wall depinning transition Albornoz, Lucas Javier; Ferrero, E. E.; Kolton, Alejandro Benedykt; Jeudy, V.; Bustingorry, Sebastian; Curiale, Carlos Javier Magnetic-field-driven domain wall dynamics in a ferrimagnetic GdFeCo thin film with perpendicular magnetic anisotropy is studied using low-temperature magneto-optical Kerr microscopy. Measurements performed in a practically athermal condition allow for the direct experimental determination of the velocity (β=0.30±0.03) and correlation length (ν=1.3±0.3) exponents of the depinning transition. The whole family of exponents characterizing the transition is deduced, providing evidence that the depinning of magnetic domain walls is better described by the quenched Edwards-Wilkinson universality class.

A task execution scheme for dew computing with state-of-the-art smartphones Hirsch Jofré, Matías Eberardo; Mateos Diaz, Cristian Maximiliano; Zunino Suarez, Alejandro Octavio; Majchrzak, Tim A.; Grønli, Tor-Morten; Kaindl, Hermann The computing resources of today’s smartphones are underutilized most of the time. Using these resources could be highly beneficial in edge computing and fog computing contexts, for example, to support urban services for citizens. However, new challenges, especially regarding job scheduling, arise. Smartphones may form ad hoc networks, but individual devices highly differ in computational capabilities and (tolerable) energy usage. We take into account these particularities to validate a task execution scheme that relies on the computing power that clusters of mobile devices could provide. In this paper, we expand the study of several practical heuristics for job scheduling including execution scenarios with state-of-the-art smartphones. With the results of new simulated scenarios, we confirm previous findings and better comprehend the baseline approaches already proposed for the problem. This study also sheds some light on the capabilities of small-sized clusters comprising mid-range and low-end smartphones when the objective is to achieve real-time stream processing using Tensorflow object recognition models as edge jobs. Ultimately, we strive for industry applications to improve task scheduling for dew computing contexts. Heuristics such as ours plus supporting dew middleware could improve citizen participation by allowing a much wider use of dew computing resources, especially in urban contexts in order to help build smart cities.

Arackar licanantay gen. et sp. nov. a new lithostrotian (Dinosauria, Sauropoda) from the Upper Cretaceous of the Atacama Region, northern Chile Rubilar Rogers, David; Vargas, Alexander O.; Gonzalez Riga, Bernardo Javier; Soto Acuña, Sergio; Alarcón Muñoz, Jhonatan; Iriarte Díaz, José; Arévalo, Carlos; Gutstein, Carolina Simon A new lithostrotian sauropod, Arackar licanantay gen. et sp. nov. is described based on a partial skeleton from the Upper Cretaceous (Campanian–Maastrichtian) beds of the Hornitos Formation, Atacama Region, northern Chile. The holotype consists of axial (cervical and dorsal vertebrae) and appendicular (humerus, femur and ischium) elements of a sub-adult specimen (ca. 6.3 m long). Autapomorphies characterizing this new titanosaur include: middle neural arches with wide and tall centroprezygapophyseal fossa + parapophyseal centroprezygapophyseal fossa (cprf + pacprf) extending on the entire anterior faces of the pedicles, but not above the neural canal, and reduced spinopostzygapophyseal laminae, shorter than the postzygapophyseal facet length. A phylogenetic analysis based on a data matrix of 87 taxa and 405 characters recovered Arackar as a derived lithostrotian titanosaur, placing it in a clade that includes Rapetosaurus + (Arackar + Isisaurus). This is the third dinosaur named from Chile and the third titanosaur from the western side of the Andes in South America.

Improving ciprofloxacin antimicrobial activity through lipid nanoencapsulation or non-thermal plasma on Pseudomonas aeruginosa biofilms Muraca, Giuliana Sabrina; Soler Arango, Juliana; Castro, Guillermo Raul; Islan, German Abel; Brelles Mariño, Graciela Antibiotic resistance is a significant challenge in the clinical practice. Pseudomonas aeruginosa is a multidrug-resistant opportunistic pathogen prevalent in hospital settings. Besides, P. aeruginosa forms biofilms that aggravate the problem since biofilms are more resilient to conventional decontamination methods than their planktonic counterparts. Due to the lack of novel antibiotics, the emergence of multidrug-resistant strains, and the resilience of biofilms to antimicrobials, new approaches based on the combination of agents are desirable. Non-thermal plasma (NTP) and nanotechnology-based strategies are an alternative to conventional decontamination/sterilization methods. NTP causes microbial cell damage or death, and it has been proved effective to inactivate more than 99% of biofilm cells after a short exposure to plasma. Nanotechnology is a promising strategy to overcome antibiotic resistance/tolerance of microbial biofilms and nanotechnology-based drug delivery systems may interact with the biofilm matrix and help remove bacterial biofilms. Nanoparticles known as “nanostructured lipid carriers” (NLCs) have been proposed as efficient and tailorable drug delivery systems since their physicochemical properties facilitate their penetrability. The aim of this study was to assess the effectiveness of ciprofloxacin-loaded NLC formulations and their potential synergy with plasma on P. aeruginosa biofilms. A decrease in the minimum inhibitory concentration was reported for biofilms exposed to plasma and free ciprofloxacin, and for biofilms treated with NLCs. The synergy between NLCs and NTP was not found under the experimental conditions used, and further research is needed to test other conditions that might result in synergy. Results show the potential of nanoparticles and plasma for biofilm inactivation.

8 fs laser pulses from a compact gas-filled multi-pass cell Rueda Suescun, Pedro Enrique; Videla, Fabian Alfredo; Witting, T.; Torchia, Gustavo Adrian; Furch, J. Compression of 42 fs, 0.29 mJ pulses from a Ti:Sapphire amplifier down to 8 fs (approximately 3 optical cycles) is demonstrated by means of spectral broadening in a compact multi-pass cell filled with argon. The efficiency of the nonlinear pulse compression is limited to 45 % mostly by losses in the mirrors of the cell. The experimental results are supported by 3-dimensional numerical simulations of the nonlinear pulse propagation in the cell that allow us to study spatio-spectral properties of the pulses after spectral broadening.

Direct measurement and modeling of intraglottal, subglottal, and vocal fold collision pressures during phonation in an individual with a hemilaryngectomy Mehta, Daryush D.; Kobler, James B.; Zeitels, Steven M.; Zañartu, Matías; Ibarra, Emiro J.; Alzamendi, Gabriel Alejandro; Manriquez, Rodrigo; Erath, Byron D.; Peterson, Sean D.; Petrillo, Robert H.; Hillman, Robert E. The purpose of this paper is to report on the first in vivo application of a recently developed transoral, dual-sensor pressure probe that directly measures intraglottal, subglottal, and vocal fold collision pressures during phonation. Synchronous measurement of intraglottal and subglottal pressures was accomplished using two miniature pressure sensors mounted on the end of the probe and inserted transorally in a 78-year-old male who had previously undergone surgical removal of his right vocal fold for treatment of laryngeal cancer. The endoscopist used one hand to position the custom probe against the surgically medialized scar band that replaced the right vocal fold and used the other hand to position a transoral endoscope to record laryngeal high-speed videoendoscopy of the vibrating left vocal fold contacting the pressure probe. Visualization of the larynx during sustained phonation allowed the endoscopist to place the dual-sensor pressure probe such that the proximal sensor was positioned intraglottally and the distal sensor subglottally. The proximal pressure sensor was verified to be in the strike zone of vocal fold collision during phonation when the intraglottal pressure signal exhibited three characteristics: an impulsive peak at the start of the closed phase, a rounded peak during the open phase, and a minimum value around zero immediately preceding the impulsive peak of the subsequent phonatory cycle. Numerical voice production modeling was applied to validate model-based predictions of vocal fold collision pressure using kinematic vocal fold measures. The results successfully demonstrated feasibility of in vivo measurement of vocal fold collision pressure in an individual with a hemilaryngectomy, motivating ongoing data collection that is designed to aid in the development of vocal dose measures that incorporate vocal fold impact collision and stresses.

Hacia la configuración del sujeto cultural converso en un manuscrito de João Pinto Delgado Gonzalez Molina, Mario Augusto Este trabajo analiza la categoría del sujeto converso como sujeto cultural, noción proveniente de la sociocrítica. En cuanto a su configuración discursiva se considera que el manuscrito Dialogos contra a Cristandade de João Pinto Delgado se ubica en el espectro de la literatura de conversos, teniendo en cuenta su delimitación genérica y las posibilidades teóricas para abordar otros textos similares del Siglo de Oro. El objetivo es abrir la discusión de la presencia de voces silenciadas ante un discurso hegemónico como una forma de legitimación desde la literatura.

Heuristic Methodology for Planning AC Rural Medium-Voltage Distribution Grids Montoya Giraldo, Oscar Danilo; Serra, Federico Martin; de Angelo, Cristian Hernan; Chamorro, Harold R.; Alvarado Barrios, Lázaro The optimal expansion of AC medium-voltage distribution grids for rural applications is addressed in this study from a heuristic perspective. The optimal routes of a distribution feeder are selected by applying the concept of a minimum spanning tree by limiting the number of branches that are connected to a substation (mixed-integer linear programming formulation). In order to choose the caliber of the conductors for the selected feeder routes, the maximum expected current that is absorbed by the loads is calculated, thereby defining the minimum thermal bound of the conductor caliber. With the topology and the initial selection of the conductors, a tabu search algorithm (TSA) is implemented to refine the solution with the help of a three-phase power flow simulation in MATLAB for three different load conditions, i.e., maximum, medium, and minimum consumption with values of 100%, 60%, and 30%, respectively. This helps in calculating the annual costs of the energy losses that will be summed with the investment cost in conductors for determining the final costs of the planning project. Numerical simulations in two test feeders comprising 9 and 25 nodes with one substation show the effectiveness of the proposed methodology regarding the final grid planning cost; in addition, the heuristic selection of the calibers using the minimum expected current absorbed by the loads provides at least 70% of the calibers that are contained in the final solution of the problem. This demonstrates the importance of using adequate starting points to potentiate metaheuristic optimizers such as the TSA.