Study of process parameters on aluminium foam formation in the Al-6Si-3Mg alloy

The aim of this research was to study the process parameters that promote foam formation by injecting N2 into Al-6Si-3Mg wt % molten alloy with silicon carbide particles additions (SiC). An experimental design was proposed, in which the contents of SiC particles were 0, 10, 30 and 50 wt %, and the overheating was defined as ΔT= TF - TL , where TL is the liquidus temperature and was determined by the cooling curve method and the foaming temperatures were selected as TF at 630, 610, 580 and 570 °C. Flow and pressure of air blow were constant, 2,0 lt/min and 4,0 atm, respectively. The foam formation was possible only under two experimental conditions, 10 wt % SiC at ΔT > 12 °C and 30 wt % SiC at ΔT > 10 °C. The foams obtained under these conditions were stable, while with other conditions of experiments, bubble coallesence occurred. Finally, it was concluded that the foam formation occurred by SiC contents lower than 30 wt % SiC and temperatures slightly above the liquidus

Inferencia de parámetros en una red de regulación génica

En el presente trabajo se abordan diferentes tipos de metodologías para la inferencia de parámetros en redes de interacción génetica. Se presentan resutados en base al estudio realizado en una red artificial específica conocida como el Represilador. Primeramente de métodos de muestreo de datos empleados. Posteriormente se presentan diversos tipos de suavizado y su desempeño en base al funcionamiento de la red estudiada. El problema es motivado por un caso de estudio real en líneas celulares de cáncer al cuál se pretende extender el presente análisis

Ranger Block III attitude control system - Manufacturing, testing, and performance

Manufacturing, test program, and performance characteristics of Range Block III attitude control syste

Capital social y redes sociales: análisis del Tercer Sector en contextos rurales

El tercer sector de acción social (TSAS) es uno de los pilares del sistema de bienestar particularmente estratégico en zonas rurales. Tomando el estudio de caso como base, este trabajo analiza el TSAS de Teruel, una provincia de Aragón (España) con población mayoritariamente rural, dispersa, y escasa. Presentamos evidencia cuantitativa y cualitativa de las redes sociales existentes y las relaciones entre las organizaciones e instituciones relevantes para el sistema de bienestar. Las conclusiones abordan una sensación generalizada de pertenencia al sector y territorio, que se relaciona con una fuerte identificación con el espacio local. En este caso, el capital social prioriza la fortaleza de los vínculos intrínsecos dentro de las redes intra-territoriales, sobre las extrínsecas o extraterritoriales. Sin embargo, se percibe que se necesitan nuevas estrategias y capitales para reforzar la conexión con las redes externas para favorecer la sostenibilidad del sector

Microcentrum tecactli, nueva especie de Phaneropteridae (Orthoptera: Tettigonioidea) del noreste de México

Microcentrum tecactli n. sp., Barrientos-Lozano, Fernández-Azuara & Rocha-Sánchez, 2018, is described from specimens collected in the Huasteca region in the State of Hidalgo Mexico. Microcentrum tecactli exhibits affinities with Microcentrum rhombifolium (Saussure, 1859). However, it differs in morphological and acoustic characters. In males the length of the stridulatory file is 4.2 mm with ca. 62 teeth vs. 4 mm ca. 55 teeth in M. rhombifolium; the subgenital plate is distally more produced, the styles are shorter and diverging; the cerci are distally narrower, and the internal genitalia is different. Lone males produce two types of acoustic signals: i) a calling song that consists of a regular buzz made up of a single syllable (one Pulse Train Group), average duration 155±38 ms (78-212 ms) (3 males; n=29 samples one min each), with inter-syllable interval (Major Interval=MaI) of 1483±364 ms (115-2394 ms). Frequency spectrum is between 4 to >30 kHz, peak frequency (fi) is at 6-16 kHz. Syllables repetition rate is 48±4.36/min (43-55; n=10 samples one min each). ii) Sequence of ticks made up of two paired-phrases with an average duration of 7.53±0.16 s (3 males; n=5 paired-sequences of ticks); phrases 1 and 2 average duration is similar in each sequence, 2.3±0 s. The number of pulses per phrase is also the same in both phrases: 29 ±0 each. Major interval duration between sequences of ticks of two paired-phrases is 5.37±2.75 s. Minor interval duration between phrases 1 and 2 is 1.42±0.12 s (1.27-1.51). Frequency range is between 4 to >30 kHz, after 30 kHz the amount of energy is minimal. Dominant frequency spectrum ranges from 4 to 22 kHz and peak frequency (fi) is at 6-16 kHz. Repetition rate of tick-paired sequences is 0.1/s (6/min); in four paired-sequences of ticks the repetition rate of pulses/ticks in phrases 1 and 2 was the same, 12.6/s each one.Se describe Microcentrum tecactli n. sp., Barrientos-Lozano, Fernández-Azuara & Rocha-Sánchez, 2018, de ejemplares recolectados en la huasteca hidalguense en México. Microcentrum tecactli n. sp., presenta afinidades con Microcentrum rhombifolium (Saussure, 1859). No obstante, difiere de ésta en caracteres morfológicos y acústicos. Los machos producen dos tipos de señales acústicas: i) el canto de llamado que consiste de un siseo regular, de una sola sílaba, cuya duración promedio es de 155±38 ms (78-212 ms) (3 machos; n=29 muestras de un min cada una), con intervalo entre sílabas (Intervalo Mayor=IMa) de 1483±364 ms (115-2394 ms). El rango de frecuencia es de 4 a >30 kHz y la frecuencia pico (fi) de 6-16 kHz. La tasa de repetición de sílabas es de 48±4.36/min (43-55; n=10 muestras de un min cada una). ii) Secuencias de pulsaciones/tics de dos frases-pares con duración promedio de 7.53±0.16 s (3 machos; n=5 secuencias-pares de pulsaciones/tics); la duración promedio de las frases 1 y 2 es igual en cada secuencia, 2.3±0 s. El número de pulsaciones por frase es también igual en ambas frases, en cada secuencia: 29±0. El intervalo mayor entre secuencias de pulsaciones de dos frases-pares es de 5.37± 2.75 s. El intervalo menor entre las frases 1 y 2 es de 1.42±0.12 s (1.27-1.51 s). El rango de frecuencia y la frecuencia pico (fi) coinciden con las del canto de llamado. La tasa de repetición de secuencias de pulsaciones-pares es de 0.1/s (6/min), en cuatro secuencias de pulsaciones-pares la tasa de repetición de pulsaciones/s en las frases 1 y 2 fue igual, 12.6 en cada una

Acoustic signal of Obolopteryx eurycerca Barrientos-Lozano y Rocha-Sánchez (Orthoptera: Tettigonidae: Phaneropterinae)

En Ensifera (Tettigoniidae: Phaneropterinae), los machos producen señales acústicas mediante estridulación tegminal; estas señales funcionan en primera instancia para atraer hembras conespecíficas sexualmente receptivas. El estudio de la bioacústica es, además, una herramienta complementaria en estudios morfológicos tradicionales, ya que estas señales son especie-específicas y permiten diferenciar especies morfológicamente similares (crípticas). Las señales acústicas representan un sistema importante de comunicación intra e interespecífico. Los miembros de la familia Tettigoniidae se destacan por la producción de señales acústicas que frecuentemente son inaudibles al oído humano [frecuencia (f) > de 20 kHz]. México posee una amplia diversidad de insectos, sin embargo, pocos estudios se han enfocado al conocimiento del repertorio acústico de éstos. En este trabajo se describe por primera vez el canto ultrasónico de llamado de Obolopteryx eurycerca Barrientos-Lozano & Rocha-Sánchez, 2016. Ejemplares en estudio se recolectaron en el municipio de Hidalgo, Tamaulipas, México. La señal acústica de llamado de los machos consiste en la producción de equemas de tres sílabas, que se emiten en forma continua por periodos largos de tiempo (± 1h). Se compara la señal acústica de O. eurycerca con la de O. castanea (Rehn & Hebard, 1914) y se discuten las ventajas de la comunicación acústica ultrasónica en Ensifera.In Ensifera (Tettigoniidae: Phaneropterinae), males produce acoustic signals through tegminal stridulation; these signals act primarily to attract sexually receptive conspecific females for mating. The study of bioacoustics is also a complementary tool in traditional morphological studies since these signals are species-specific and allow the differentiation of morphologically similar (cryptic) taxa. Acoustic signals represent an important intra and interspecific communication system. Members of the family Tettigoniidae are remarkable for producing acoustic signals that are frequently inaudible to the human ear [frequency (f) > 20 kHz]. Although Mexico is endowed with an extensive diversity of insects, few studies have focused on their acoustic repertoire. In this work, we describe for the first time, the ultrasonic acoustic calling signal of Obolopteryx eurycerca Barrientos-Lozano & Rocha-Sánchez, 2016. The specimens studied were collected in the municipality of Hidalgo, Tamaulipas, Mexico. The males’ calling signal is made up of echemes of three syllables, emitted in a continuous fashion for long periods of time (± 1h). The acoustic signal of O. eurycerca is compared with that of O. castanea (Rehn & Hebard, 1914) and the advantages of ultrasonic acoustic communication in Ensifera are discussed

Amaranth production in Tulyehualco Xochimilco, Mexico City

During 2010-2019 amaranth has been cultivated in at least 11 states in Mexico, in Mexico City is grown in the municipalities of Xochimilco, Milpa Alta and Tláhuac, highlighting Xochimilco for harvested area and production with 82.9 ha and 91.7 t which represents 60.4% and 55.6% respectively. The objective of the research is to know the form of production and commercialization of amaranth in Tulyehualco, Xochimilco to identify and propose improvement actions. The information was obtained through the application of a survey through a non-probability sampling for convenience, with the criterion of selection of individuals who were willing to be surveyed, and the survey was applied from September to December 2019, to 35 producers, 3 marketers and 4 transformers. The production of amaranth is carried out in two ways, by means of chapin and directly, by its traditional way of producing it the crop is ancestral in those areas, so there is a millenary knowledge of the families that are dedicated to the planting of the crop. Amaranth production has a positive cost benefit ratio R (B / C), however in direct sowing production this is better. Planting with a seedbed (Chapin) has higher costs and yield, however, this does not compensate the producer in profits. For a potential impact at the amaranth production level, the adoption of technologies related to density, nutrition and technical recommendations for pest and disease control.Objective: To know the form of production and commercialization of amaranth in Tulyehualco, Xochimilco, to identify and propose improvement actions. Methodology: During 2010-2019, amaranth was cultivated in at least 11 states in Mexico, while in Mexico City it is grown in the municipalities of Xochimilco, Milpa Alta and Tláhuac. Xochimilco stands out due to harvested area and production, with 82.9 ha and 91.7 t which represents 60.4% and 55.6% respectively. The information was obtained through the application of a survey through non-probability sampling for convenience, with the selection criterion of individuals who were willing to be surveyed, and the survey was applied from September to December 2019, to n=35 producers, n=3 marketers and n=4 transformers. Amaranth production is carried out in two ways, by means of chapin and directly, and due to its traditional way of producing the crop is ancestral in those areas, so there is a millenary knowledge of the families that are dedicated to planting the crop. Results: Amaranth production has a positive cost benefit ratio R (B / C) although production is better in direct sowing. Planting with a seedbed (Chapin) has higher costs and yield, however, this does not compensate the producer in profits. Conclusions: For a potential impact at the level of amaranth production, the adoption of technologies related to density, nutrition and technical recommendations for pest and disease control is necessar

Señal acústica y redescripción de Gongrocnemis (Gongrocnemis) munda Brunner von Wattenwyl, 1895 (Orthoptera: Tettigoniidae)

En los ortópteros de la superfamilia Tettigonioidea las señales acústicas son de especial interés, ya que juegan un papel importante en el apareamiento y están involucradas en el reconocimiento intraespecífico macho-hembra. La señal acústica de llamado permite al macho atraer individuos del sexo opuesto a corta o larga distancia. En este trabajo se presenta la señal acústica de llamado de Gongrocnemis (Gongrocnemis) munda (Tettigoniidae: Pseudophyllinae) y se hace una breve redescripción de esta especie, en particular de la hembra, no descrita previamente. Ejemplares de G. (G.) munda se recolectaron en San Felipe Orizatlán (1♂: 1♀; 27.XI.2017) e Ixcatlán, Huejutla de Reyes (2♂: 2♀; 22.I.2013), Hidalgo, México. G. (G.) mexicana se recolectó en Cd. del Maíz, San Luis Potosí (1♀; 19.VII.2003). Los machos producen la señal acústica de llamado principalmente durante la noche y está compuesta por pares de equemas que se emiten ininterrumpidamente por periodos de una hora o más. Machos de G. (G.) munda producen 6.0 ± 0.9 (d.e) equemas/min (n=30 min; tres machos, 10 min cada uno). La duración por equema-par es de 3.97 ± (d.e) 1.2 s (2.7-8.0 s) (n=30 equemas-pares). El análisis de frecuencia muestra la mayor liberación de energía de 16-40 kHz, con una fi pico de 20-38 kHz. La hembra es similar al macho, pero más robusta. El color general del cuerpo es verde oliváceo con matices color crema y manchas marrón obscuro. La longitud es de 32.7 ± 1.5 mm (n=3). Esta especie habita selva mediana y bosque de encino, se encuentra generalmente sobre la copa o el tronco de los árboles. Durante el día permanecen quietos y ocultos, siendo activos por la noche.In the Orthoptera of the superfamily Tettigonioidea acoustic signals are of special interest since they play an important role in the process of pair formation and are directly involved in intraspecific male-female recognition. The calling signal usually allows the male to attract individuals of the opposite sex at short or long distance. In this work, we present the acoustic signal of Gongrocnemis (Gongrocnemis) munda (Tettigoniidae: Pseudophyllinae) and provide a brief redescription of this species, in particular of the female not formally described previously. Specimens of G. (G.) munda were collected in San Felipe Orizatlán, (1♂: 1♀; 27.XI.2017) and Ixcatlán, Huejutla de Reyes (2♂: 2♀; 22.I.2013), Hidalgo, México. G. (G.) mexicana was collected in Ciudad del Maíz, San Luis Potosí (1♀; 19.VII.2003). Males produce the calling acoustic signal mainly at night, and it is composed of paired-echemes. The acoustic signal may be produced uninterruptedly for long periods, 1 h or more. Males of G. (G.) munda produce 6.0 ± 0.9 (s.d) echemes per minute (n=30 min; three males, 10 min each). Duration per paired-echeme is 3.97 ± (s.d) 1.2 s (2.7-8.0 s) (n=30 echemes). Frequency analysis showed the highest energy release between 16-40 kHz, with a fi peak in the range of 20-38 kHz. The female is similar to the male, but more robust. The general body color is olive-green, with cream spots and brown marks. The average length is 32.7 ± 1.5 mm (n=3). The ecosystem this species lives on is tropical evergreen and oak forest; it is found usually on the foliage or trunk of trees. During the day, adults remain quiet and hidden, being active at night