In this study, cellular spacing, porosity and corrosion of 1050 aluminum alloy subjected to the different levels of Gamma radiation was examined using a Gammacell Co-60 type irradiator, with activity of 16.13 TBq and dose rate around 6.98 Gy/min. Samples were extracted from an aluminum ingot, which was obtained with directional solidification apparatus. This upward directional solidification technique allowed obtaining of aluminum samples under different conditions of cooling rates. Firstly, cooling rates were determined during solidification experiment and then correlated to the cellular spacings and porosity content. The experimental results pointed out that cooling rates exerts a strong effect on the microstructural patterns and porosity formation. Laws have been determined, indicating that increase in cooling rates favored a refinement effect on as-cast microstructure and a decrease in porosity content. Furthermore, measurable effects of different levels of the Gamma radiation on the microstructure, porosity and corrosion for samples of 1050 aluminum alloy, were determined. The experimental results show that Gamma radiation has favored changes in cellular spacings, porosity formation and corrosion behavior. From this results, one can conclude that coarser microstructures, porosity formation and corrosion are favored by prolonged thermal annealing caused by temperature field generated during Gamma radiation exposure. On the other hand, even after the exposure to different levels of Gamma radiation, the microstructure and porosity observed in as-cast samples are still strongly dependent of the cooling conditions. study spacing 105 Co60 Co 60 Co-6 irradiator 1613 16 13 16.1 698 6 98 6.9 Gymin Gy min Gy/min ingot apparatus Firstly content ascast as cast Furthermore behavior microstructures hand 10 Co6 Co- 161 1 16. 69 9 6.

Abstract Metal additive manufacturing is rapidly developing technology, but its application in wider scale is limited by several factors. One of these is expensive raw material, because it requires certain physical properties. Two most popular metal additive manufacturing methods are printing from powder and printing from wire. Wire is usually produced by drawing it from rod. Rod can be produced by directional solidification, which is well known method to study the microstructure formation depending on various parameters during solidification. In this study directional solidification of A360 aluminum alloy with electromagnetic interaction is investigated. Aluminum alloy is induction melted and then directionally solidified into the rod 12-20 mm in diameter. Aim of this work is to investigate the role of axial DC magnetic field and electric current interaction on the grain refinement and mechanical properties of A360 aluminum alloy. It is found that electromagnetic interaction can be the approach to refine the grains, regulate the growth of oriented columnar grains and to improve mechanical properties of the material. technology factors material wire A A36 investigated 1220 12 20 12-2 diameter A3 122 1 2 12-

ABSTRACT This paper shows the obtaining process of a digital beamformer of multiple simultaneous directional patterns for signals reception using the ARRadio evaluation board. The board is based on the integrated transceiver AD9361 and guarantees the reception, digitization and seending to an FPGA (Field Programmable Gate Array) of the received radio waves by each radiofrequency channel. The FPGA is located on the TR4 Development Board. Communication between FPGA and ARRadio is realized through a high speed connector. On the programmable device are performed AD9361’s configuration and control, multichannel calibration process based on Fourier Transform (as method of measuring the delay between channels) and beamforming of multiple simultaneous directional patterns digitally. Simulink is used as design tool for digital system develop. Finally is realized the implementation and experimental verification of multiple digital beamforming system.

RESUMEN El presente trabajo muestra el proceso de obtención de un formador digital de múltiples diagramas direccionales simultáneos para la recepción de señales utilizando la tarjeta de evaluación ARRadio. La tarjeta se basa en el transceptor integrado AD9361 y garantiza la recepción, digitalización y envío hacia un FPGA (del inglés Field Programmable Gate Array) de las ondas de radio recibidas por cada canal de radio frecuencia. El FPGA se encuentra ubicado en la tarjeta de desarrollo TR4. La comunicación entre el FPGA y cada ARRadio se realiza a través de un conector de alta velocidad. En el dispositivo programable se efectúan la configuración y control del AD9361, el proceso de calibración multicanal basado en Transformada de Fourier (como método de medición del retardo entre canales) y la formación de múltiples diagramas direccionales simultáneos de manera digital. Simulink es usado como herramienta de diseño para el desarrollo del sistema digital. Finalmente se realiza la implementación y verificación experimental del sistema formador de múltiples diagramas direccionales simultáneos.

BACKGROUND: South African tourism is evolving towards accommodating disabled people. Within the same standpoint, the country receives ageing tourists as a major international tourism market from the Global North, whose access needs are similar to disabled people. The present article explored 'blind and blank spots' in the extant literature on tourism-impairment disability as a synchronised field within academic research to provide theoretical insights and gaps for the disability-tourism research community to consider the composite concept instead of individualistic concepts. OBJECTIVE: The objectives were: (1) to track knowledge development from 1990 to 2018 using a narrative literature review approach and (2) to justify future research areas previously overlooked and understudied within a tourism-impairments-disability perspective in South Africa and beyond. METHOD: A narrative literature review search strategy was used. Keywords and synonymous terms were used in electronic searches of Scopus, ScienceDirect, Sabinet Online, Emerald Insights Journals, African Journals and Google Scholar. The literature screening process used predetermined inclusion and exclusion criteria for the data source. Content thematic analysis was adopted for the present study RESULTS: The findings reflect a dearth of tourism-impairments-disability research in South Africa. Nonetheless, there is an observable pattern of slow growth in research after the 2000s. The extant literature is skewed towards the tourism supply side and sporadic on tourism demand (tourist experiences), education and skills development. CONCLUSIONS: It is clear that the absence of scientifically developed knowledge on disability-impairments-tourism affects inclusive tourism growth. Therefore, the research community should consider disability-inclusive (accessible) tourism management, human resources and marketing practices and knowledge for teaching material in future research. CONTRIBUTION: The article mapped and provided insights that sets a research agenda for tourism research community to see the gaps in literature and/or knowledge for accessible tourism (disability-inclusive) tourism to be a game changer as found by UNWTO (2020) with low-resources setting. Thereby setting a tone towards call for more research that can uncover an economic narrative that shows a relationship between skills development, labour and consumer markets for the participation of diverse disabled persons as such is shown as understudied in Low-to-Middle income earning countries like South Africa.

Guias de ondas são dispositivos que permitem a propagação de ondas eletromagnéticas direcionadas. As ondas guiadas ocorrem quando as equações de onda são atendidas respeitando as condições de contorno no guia. Além de sua aplicação prática, o estudo dos campos elétrico e magnético é altamente relevante no ensino superior, em disciplinas tais como eletromagnetismo e dispositivos de microondas. Neste artigo, é apresentado e disponibilizado um código numérico para a visualização animada dos campos eletromagnéticos em guias de onda retangulares. Para isso, são revisadas as equações de propagação em guias de onda para modos TE e TM. O referido código, em Matlab®, possibilita ao usuário a escolha das dimensões do guia, do tipo de onda, do modo, da vista e da frequência de operação. O artigo apresenta ainda um exemplo computado para um guia retangular comercial do tipo WR-90, através da exemplificação dos modos TE 10 e TM 21. O presente programa computacional é um objeto educacional de código aberto de alta relevância ao aprendizado de eletromagnetismo.

Waveguides are devices that allow the propagation of directional electric magnetic waves. Guided waves occur when the wave equation is satisfied considering the boundary conditions in the waveguide. Besides its practical issue, studying electric and magnetic fields is highly relevant in electromagnetism and microwave device courses. In this article, we present and provide a numeric code for an animated visualization of the electromagnetic waves in a rectangular wave guide. For this, the waveguide propagation equations for TE and TM mode are reviewed. This code, in Matlab®, allows the user to select wave guide dimensions, wave and mode type, view type and operation frequency. An example for the TE 10 and TM 21 wave modes propagating through the commercial WR-90 waveguide is presented. This program is a highly relevant open-source educational object when it comes to learning electromagnetism.

This paper is carried out in the coastal area of Bahía Creek and its surroundings, highlighting 15 km to the west Caleta de los Loros. This area is located on the coast of Río Negro province, which is part of the San Matías gulf. Bahía Creek is located precisely at 41º 05´S, 63º 56´ W. It belongs to the department of Adolfo Alsina and it is located 70 km SW of Viedma city, capital of the province and 70 km E of San Antonio Oeste port (Fig. 1). The main objective of this work is a morphological classification of the dunes present in the dunefield of Bahía Creek, based on the proposed classifications by McKee (1979), Lancaster (1995), Hesp (2011) and Sanjaume and Gracia (2011). For this it is necessary to observe satellite images and aerial and field photographs, together with the study of wind data. With this information it is also possible to know the factors that can condition the location of the dunes, their migration, their mobility index according to Lancaster (1988) and the sand drift potential (DP), the resulting drift direction (RDD), the resulting drift potential (RDP) and the directional variability of the wind through the RDP/DP relationship through the methodology proposed by Fryberger (1979). The used material consisted of aerial photographs from 1986 from the Servicio Geológico Minero Argentino, scale 1:80.000; the digital elevation model (DEM) of the ALOS satellite and Landsat 8 images from 2017, the latter of 30 m of spatial resolution. The images available in Google Earth, Earth Engine and Bing Maps were also used. The wind data used correspond to the records of the Servicio Meteorológico Nacional weather stations located in the towns of Viedma and San Antonio Oeste (SAO). Within these winds, those capable of mobilizing the material available in the study area (effective wind), of an average grain size of 0.25 mm (Toffani, 2018), are those that reach speeds equal to or greater than 6.7 m/s. This value was calculated using the equations proposed by Bagnold (1954). The effective wind was recorded in 34% of the total measurements within Viedma and SAO stations. In Viedma (Fig. 2) the main effective wind directions are NW (13.9%), and SW (10.1%), while in SAO (Fig. 2) the NW direction (18.8%) also predominates, followed by WNW (10.4%). These values suggest that the net displacement of the dunes occurs from NW/SW to SE/NE. Subsequently, applying the mobility index, it was obtained that the dunes, on average, correspond to active except in the interdune, with a value of 124. The annual value of DP is 1090, the RDP 392 and the annual RDD direction is 76 o, indicating a displacement of the sediments towards the ENE (Fig. 3). The directional variability of the wind regime, characterized by the RDP/DP ratio, shows the value of 0.36. This means that Bahía Creek is located within a high energy environment, with a wind regime between complex and bimodal. The annual rate of migration for the dunes studied, which are located within fields of dunes 2, 5 and 7, between 1986 and 2017 was 6.02 ± 0.3 m/ year (Fig. 4), towards NE - SE. The dunefield is transgressive and is characterized by a gentle relief that goes from 0 to 60 - 90 meters above sea level from the beach towards N and E. The active dunes rest on a field of stabilized dunes and this in turn is located on an old dissected alluvial plain. The dunes can reach a relative height of 16 m and are composed of medium to fine sands, generally very well sorted, with the exception of some well sorted. Within the classification itself (Fig. 5), the dune fields 1 (Fig. 6a), 3 (Fig. 6c), 5 (Fig. 8a) and 6 (Fig. 8b) are characterized by the predominance of crescentic dunes. Field 2 has mainly linear and reversible crest dunes (Fig. 6b). Field 4 is characterized by star dunes (Fig. 6d). Field 7 is composed of symmetric, asymmetric and lateral coalescence parabolic dunes (Fig. 8c - d). While field 8 is represented by embryonic dunes (Fig. 9a - b), field 9 by climbing dunes (Fig. 9c) and field 10 by hanging dunes (Fig. 9d). Echo dunes (Fig. 10a), falling dunes from the cliff (Fig. 10b) and enveloping dunes (Fig. 10c) were also recorded in the field. In addition, within the different sectors mentioned, the formation of nebkas occurs (Fig. 10d). The wavelengths vary between 30 m and 350 m, the lowest values are after the creek, that is where the dunefield begins, and in the most distal part, east of the dune field 6. This sector is also the one that records the highest values. This distribution is coherent, since the first accumulations are of smaller size and close to each other, in general they are growing and having greater wavelength, until reaching a 57 maximum. Where transport begins to decrease they acquire smaller sizes. The greatest lengths, up to 1 km, due to the development of its arms, are reached by the parabolic dunes. The smallest, 10 m, are those presented by the barchans. Regarding the width, the latter are also those that have smaller sizes, 10 m, while the largest correspond to coalescent parabolic dunes and transverse or barchanoid ridges, which are between 500 m and 600 m. It is also observed that the larger the size of the dunes in terms of length and width, the wavelength is greater. Variations in wind and sand transport rate at different time and space scales appear to be the most important control of their size and spacing. These factors, together with vegetation, humidity, input of sand, topography and constructions or anthropogenic processes, influence the distribution of the active dunes and at the same time in the location of the different types of dunes. The most relevant for the population of Bahía Creek are the constructions that act as an obstacle to the transport of sediments by the wind. They difficult the passage of winds coming mainly from the S, which contribute to the movement of the dunes towards the NE, leaving them more relative weight to the winds of the W and the NW. The latter cause the fastest advance of the dunes towards the E and SE, that is, where the buildings are. Bahía Creek dunefield, due the types of dunes and their distribution, shows great complexity, mainly due to the variations in the effective winds, and that over time generate compound and complex dunes. In Argentina, coastal dunefields with similar characteristics are develop, for example, around San Antonio Oeste and Este, in Río Negro province (Carbone et al., 2007); in the south and east of Buenos Aires province (Barrera Medanosa Austral y Oriental) (Bértola and Cortizo, 2005; Cortizo and Isla, 2007, 2012; Bértola et al., 2009); and in Península Valdés, Chubut province (del Valle et al., 2008). However, Bahía Creek has exceptional characteristics due to the possibility that offers to appreciate a natural environment with different geomorphological features with virtually no anthropic disturbance. Among these are beaches, cliffs and mainly the vast dunefield, which enters the continent with a concentration and striking diversity of dunes. It is a site that is not yet highly exploited by urbanization and tourism and allows visitors to access an almost virgin and pristine environment, which includes Caleta de los Loros, Pozo Salado and Punta Mejillón Protected Area. This last one is conformed to a greater extent by a tidal plain, which added to the rest of the coastal environment and to the dunefield, makes the area have a great diversity of species. In addition, the importance of the study of the dunefield lies in its proximity to the seaside town of Bahía Creek, which acquires more visitors over the years and is affected by the migration of the dunes, which sometimes have already covered houses or arrived at a distance very close to them and continue to move in that direction.

El presente trabajo se llevó a cabo en el área de Bahía Creek, en la costa sur de la provincia de Río Negro, NE de Patagonia, Argentina. El mismo consta de una clasificación morfológica de las dunas presentes en el campo eólico de Bahía Creek, junto con un estudio del índice de movilidad y el potencial anual de deriva de arena (DP), sumado a la dirección de deriva resultante (RDD) y al potencial de deriva resultante (RDP); además de la tasa de avance de las dunas entre los años 1986 y 2017 y características granulométricas de las arenas que las componen. Estas tareas fueron posibles gracias al uso de imágenes satelitales, fotografías aéreas y de campo, muestreo in situ, modelos de elevación digital y datos de viento recolectados en estaciones cercanas al área de estudio. Las dunas estudiadas se agruparon en diez sectores con características comunes, definidos por las morfologías dominantes. Dentro de estos destacan los referidos a dunas semilunares (barjanes y cordones barjanoides y transversales), lineales, estrella, parabólicas, embrionarias, remontantes y colgadas, junto con dunas oblicuas, reversas, nebkas y, a escala de campo, dunas eco, descendentes y envolventes. A su vez, dentro de cada sector hay dunas compuestas y/o complejas, pudiendo haber más de un tipo de duna. Teniendo en cuenta el índice de movilidad, las dunas resultan en promedio activas a excepción de la interduna, mientras que el potencial de deriva de arena calculado fue de 1090, con una dirección de deriva resultante de 76º y un RDD de 391. Asimismo la tasa de migración media entre los años estudiados (1986 - 2017) fue de 6,02 ± 0,3 m/año. Estos estudios, además de brindar una clasificación del campo de dunas de Bahía Creek, escasa hasta la actualidad, permiten tener un conocimiento sobre por qué las dunas en general se ubican en el área de estudio y cómo se produce la división de las mismas dentro del campo eólico. Esto último se debe a factores tales como la vegetación, la humedad, el aporte de arena, los vientos, la topografía y construcciones o procesos antropogénicos. Además se realizaron comparaciones con campos de dunas con similares características ubicados también en la costa Argentina.

Within the context of a conflictive socio cultural ethnical field of one directional and inequal intercultural relations, the autor analyses the health / diseases processes and bucal care in the mapuche communities in the urban locality of Allen (PUEL PUJV) and the rural community of Aguada Guzmán (ELEL KIMUN), de Rio Negro province.

Dans le contexte d'un champ socioethnique conflictuel de relations interculturelles inégales, l'auteur analyse les processus de santé/maladie buccodentaire dans les communautés mapuches de la ville urbaine d'Allen (PUEL PUJV) et de Aguada Guzmán (ELEL KIMUN), province de Rio Negro.

En el contexto de un campo socioétnico conflictivo de relaciones interculturales unidireccionales y desiguales, la autora analiza los procesos de salud/enfermedad atención bucal en las comunidades mapuches en la localidad urbana de Allen (PUEL PUJV) y rural EL de Aguada Guzmán (ELEL KIMUN), provincia de Rio Negro.

Abstract For the development of a geothermal field, the understanding of fracture distribution, hydrology and tectonic evolution of the site through structural characterization of the natural system is a prerequisite to the drilling of exploratory wells. In order to image the underground shape of approximately planar, relatively permeable, geologic features (fractured rock-volumes around fault planes) and to detect hot rock volumes, geologic and geophysical surveying is carried out. A strong positive magnetic anomaly, nearly circular in 2D, characterizes the middle of Cuitzéo lake, Michoacán, Mexico, apparently not related with a volcanic structure on the surface. It may instead be associated to the geothermal system in the area which yields at present hot springs at the southern shore of the lake, at boiling temperatures. In this study, we conducted a ground magnetic survey within and around Lake Cuitzeo with the aim of characterizing this anomaly, following one-kilometer-spaced survey-lines and covering an area of approximately 100 km2. To enhance interpretability, we applied computational filters based on directional derivatives (vertical and horizontal) to our reduced-to-pole magnetic-field raw data - illuminating underground faults and other permeable pathways for fluids and delineating contacts between differently magnetized rocks, through maxima and minima on maps. While most filters used were able to define the basic configuration of the system, we found that computational filters working with ratios of derivatives (vertical and horizontal) were able to better account for the depth of a magnetic source. Also, faults were more clearly imaged on maps. We could mainly highlight ~E-W and ~N-S striking fault-systems, respectively belonging to the ~N-S Trans-Mexican Volcanic Belt extensional tectonics and to the ~E-W Basin & Range, both with lateral movements and still active today. We interpret the magnetic source as a magma body (related to the volcanism of Michoacán-Guanajuato Volcanic Field) that remained trapped during its ascent under Cuitzeo lacustrine sedimentation, during the last 500 ka, forming the once stronger geothermal system.

Resumen Para el desarrollo de un campo geotérmico, el conocimiento de la distribución de fracturas, la hidrología y la evolución tectónica del sitio a través de la caracterización estructural del sistema natural es un requisito previo a la perforación de pozos exploratorios. Fallas y fracturas representan vías preferenciales por el flujo de fluidos en el subsuelo y pueden ser detectadas mediante investigaciones geológicas en la superficie y geofísicas en el subsuelo. Una anomalía magnética positiva y de forma sub-circular en planta se encuentra en el medio del lago Cuitzeo, México. A través de un levantamiento geomagnético dentro y alrededor del área que comprende la anomalía tratamos caracterizar el reservorio geotérmico que, al sur del lago, está notificado por manifestaciones hidrotermales. Utilizando filtros computacionales basados sobre el uso de operaciones con las derivadas de valores de campo a los datos magnéticos grabados, hemos puesto en luz algunas de las estructuras que influencian la circulación de los fluidos en el sistema geotermal. Nuestra atención se focalizó sobre fallas ~N-S and E-W, pertenecientes respectivamente a la tectónica Básin & Range (B&R) y a la del Cinturón Volcánico Mexicano (CVM). Según nuestra interpretación, la interacción de dos o mas estructuras de diferentes orígenes (B&R y CVM), además del entorno geodinámico específico (subducción de zona de fracturas), facilitó el surgimiento de cuerpos magmáticos básicos del profundo que, bloqueados por la capa argilosa de sedimentación lacustre del Cuitzeo, dieron lugar, enfriándose lentamente, al sistema geotermal y contribuyeron a la formación de la anomalía magnética.

Palaeomagnetic data from a sedimentary section spanning the Holocene and terminal Pleistocene (~13 kya) from Rose Cottage Cave, eastern Free State (South Africa), are reported. The palaeomagnetic analysis took into account rock magnetism and directional analysis. The former reveals that most samples show stable single domain and superparamagnetic particles of Ti-poor magnetite and haematite. Natural remanent magnetisation directions were determined by progressive alternating field demagnetisation methodology. Directional analysis shows normal directions between samples 18 to 39 and 85 to 92; however, during the Early and Late Holocene in samples principally from RC40 to 84 'anomalous' directions occurred. There is a significant westward shift in declination of ~80°, and a conspicuous fluctuating inclination in the lower part of the section during the Early Holocene at ≥9.5 kya and before ~12.0/13.0 kya. This palaeomagnetic record might become a chronostratigraphical marker for latest Pleistocene/Holocene sedimentary deposits in South Africa. Our two new accelerator mass spectrometry radiocarbon dates for the sampled deposit are 9500±50 BP and 1115±30 BP. SIGNIFICANCE: •The study provides new accelerator mass spectrometry dates on the chronological sequence existing in Rose Cottage Cave. •The findings contribute to the knowledge of the geomagnetic field behaviour since the terminal Pleistocene to the Late Holocene in a period spanning the last 13 000/12 000 years. •This palaeomagnetic record might become a chronostratigraphical marker for the latest Pleistocene/Holocene sedimentary deposits in South Africa.

Resumo: Serpentes compõem um diverso grupo de animais vertebrados terrestres pertencentes à ordem Squamata. Apesar de serem um dos grupos mais diversos do mundo, na Amazônia, as informações acerca da taxonomia e distribuição de serpentes são limitadas quando comparadas com as disponíveis para outros grupos de vertebrados. Além disso, na Amazônia existe um viés de amostragem em áreas geograficamente próximas aos centros urbanos e locais densamente povoados. Isso por sua vez leva a falsas diferenças de distribuição em áreas pouco amostradas. Neste artigo nós apresentamos a composição de assembleias de serpentes em seis áreas na Amazônia brasileira, baseada em amostragens de campo padronizadas e realizadas durante quatro anos. Foram amostradas 70 espécies de oito famílias: Typhlopidae (n=1), Leptotyphlopidae (n=1), Anillidae (n=1), Boidae (n=5), Colubridae (n=15), Dipsadidae (n=35), Elapidae (n=7) e Viperidae (n=5). A maior riqueza foi registrada no Rio Trombetas e a menor no Rio Jatapu. A beta diversidade total foi de 0.40 e a substituição foi a principal força que estruturou as comunidades (72.5%). A Procura Visual Limitada por Tempo foi o método que registrou a maior abundância de serpentes nas áreas amostradas (44.1%) e também a maior riqueza (n=40). Entretanto, algumas espécies foram registradas somente por outros métodos como armadilhas de interceptação e queda. Apesar do grande número de espécies registradas, nenhuma das áreas compreendeu mais de 40% das espécies amostradas em todas as áreas, indicando que as serpentes são pouco detectadas mesmo com grande esforço amostral em diferentes áreas da distribuição das espécies.

Abstract: Snakes are a diverse group of terrestrial vertebrates of the order Squamata. Despite that, in the Amazonian biome, information about distribution and identification of snakes is limited when compared to other groups. Additionally, in Amazonia there is a sampling bias towards areas geographically close to urban centers and more densely populated areas. This in turn leads to false distribution gaps in poorly accessible areas of Amazonia. In this article we report the composition of snake assemblages in six areas of the Brazilian Amazonia, based on field sampling conducted over four years using standardized methods. We sampled 70 species from eight families: Typhlopidae (n=1), Leptotyphlopidae (n=1), Anillidae (n=1), Boidae (n=5), Colubridae (n=15), Dipsadidae (n=35), Elapidae (n=7), and Viperidae (n=5). The largest number of species was recorded in the Trombetas River area and the lowest in the Jatapu River area. The total beta diversity was 0.40 and the snake assemblages were structured mainly by replacement (72.5%). The time-limited search was the method that recorded the greatest number of individuals in the studied areas (44.1%) and also the greatest number of species (n=40). However, some species were recorded only by other methods such as interception by pitfall traps with directional fences. Despite the large number of species sampled in the study, no particular area comprised more than 40% of species registered in all the areas, indicating that snakes are poorly detected even with large sampling effort across multiple areas of a species distribution.

Abstract Cartography in hydrology is one of the traditional ways of representing the spatial variability of climatic and environmental events. However, attention is hardly ever focused on how, for example, isohyets maps are constructed. Incorrect selection of the spatial interpolation method can lead to errors in the estimation of magnitudes. Because the early warning systems that work in the State of Querétaro and are used by the Civil Protection authorities during the rainy season, they transmit their information every minute. It is necessary to have spatial interpolation tools that allow us to obtain values with a minimum of error. The warning systems have a spatial interpolation subroutine (cartography) incorporated, in such a way that the authorities can estimate in real time the precipitation level in a determined place, even though there is no meteorological station in situ. A spatial and temporal characterization of the variability in the hourly precipitation of the metropolitan area of Santiago de Querétaro is carried out. Rain gauges are used, measured at each minute of the ten most intense storms recorded in the years 2013, 2014 and 2015. Using directional variograms, distance between stations and an anisotropy scheme, the optimal parameters to be used in a Kriging interpolation are obtained. The comparison of the variograms, for example for the month of July, for the years 2013, 2014, 2015 made it possible to identify that the range of validity of the measurements (distance) does not change in spite of the fact that the theoretical formulation of the variogram is modified. In this way, a parameter called alpha can be introduced to explain the spatial variability of rainfall. This is useful because it shows that the precipitation record is a function of the distance at which the observations are valid, something that was already known but not verified in urban areas. The results show that in June there is a greater variability of precipitation in the metropolitan area and that the precipitation pattern has a direct correlation with the distance between rain stations. The analysis allows the correct selection of directional variograms to be used for spatial interpolation and rain field mapping. As an example, data are taken from the storm of August 18, 2014, which was a severe storm that caused severe economic and material damage in the metropolitan area of the city of Queretaro. With this scheme of variability was made the mapping of the isohyets of the storm that day, considering an interpolation with traditional Kriging and a cartography affected by a directional variogram and the alpha parameter. In order to validate the proposed methodology, a cross validation was carried out with the Historical Center rain station, as it is the area most attended by the authorities during the rainy season. The station data were omitted in the estimation of the interpolation of the grid to generate the cartography. Also, 7800 points were calculated to generate a grid interpolated with the proposed formulation and it was demonstrated that the estimated values are acceptable. The results of this work will make it possible to calibrate the spatial interpolation models that work in the hydro-informatics tools used by the Civil Protection authorities.

Resumen La cartografía en hidrología es una de las formas tradicionales de representar la variabilidad espacial de eventos climáticos y ambientales. Sin embargo, pocas veces se pone atención a cómo se construyen, por ejemplo, los mapas de isoyetas. Una incorrecta selección del método de interpolación espacial puede ocasionar errores en la estimación de magnitudes. Se realiza una caracterización espacial y temporal de la variabilidad en la precipitación horaria de la zona metropolitana de Santiago de Querétaro. Se utilizan láminas de lluvia medidas a cada minuto de las diez tormentas más intensas registradas en los años 2013, 2014 y 2015. Utilizando variogramas direccionales, distancia entre estaciones y un esquema de anisotropía se obtienen los parámetros óptimos a emplear en una interpolación por Kriging. Los resultados muestran que en el mes de junio existe una mayor variabilidad de la precipitación en la zona metropolitana y que la lámina de precipitación tiene una correlación directa con la distancia entre estaciones. El análisis permite seleccionar de forma correcta los variogramas direccionales que deben emplearse para la interpolación espacial y la cartografía de campos de lluvia.

Resumo A pesquisa objetivou avaliar os níveis de alteração dos aquíferos a partir da instalação de parques eólicos sobre dunas no litoral do Ceará por meio dos métodos de vulnerabilidade GOD e POSH, fluxo subterrâneo e aplicação da análise multivariada para subsidiar no monitoramento da qualidade da água subterrânea na área. Foram realizadas três etapas de campo: cadastro dos poços e fontes de poluição, medição de nível d’água e coleta de amostras de água subterrânea para análises laboratoriais. Os resultados obtidos com o método GOD demonstram o predomínio de moderada a alta vulnerabilidade natural do aquífero à poluição nas áreas do entorno do parque eólico do distrito de Amarelas (praia de Xavier e Ziu) que estão próximas ao parque eólico e que foram classificadas de acordo com o método POSH, com elevadas cargas poluidoras. Os vetores direcionais do fluxo subterrâneo estão com sentido para a praia de Xavier (vulnerabilidade alta), sede de Amarelas (vulnerabilidade moderada), Tapuiu e Montevidéu (vulnerabilidades baixas), significando que o parque eólico pode ser um potencial impacto no rebaixamento do lençol freático na área. A partir da análise multivariada, observa-se que as características das águas subterrâneas estão fortemente relacionadas com a formação geológica dos poços (Dunas e Barreiras), conferindo todas as amostras dentro do Valor Máximo Permitido para consumo humano para STD, dureza, turbidez e pH. Ressalta-se a importância em realizar estudos preliminares dos aquíferos subjacentes às áreas onde pretende-se instalar parques eólicos, considerando-se os níveis de vulnerabilidade e os riscos à poluição e alteração do aporte hídrico.

Abstract This research evaluated the levels of alteration of aquifers caused by installation of wind farms on dunes on the coast of Ceará, using the GOD and POSH methods of vulnerability, underground flow, and the application of multivariate analysis to subsidize the monitoring of groundwater quality in the area. There were three stages of field study: registering the wells and pollution sources, measuring the water levels, and groundwater sampling for laboratory analysis. The results obtained with the GOD method demonstrate the predominance of moderate- to high natural vulnerability of the aquifer to pollution in the areas close to the wind park in the district of Amarelas (Xavier and Ziu beach) and revealed high pollution loads according to the POSH method. The directional vectors of the underground flow are meaningful for Xavier Beach (high vulnerability), the center of Amarelas (moderate vulnerability), Tapuiu and Montevideo (low vulnerability). This indicated that the wind farm may have a potential impact on the lowering of groundwater in the area. From the multivariate analysis, it is evident that the groundwater characteristics are strongly related to the geological formation of the wells (Dunas and Barreiras), showing all samples within the Tolerable Maximum Value for human consumption for TDS, hardness, turbidity, and pH. It is vital to carry out preliminary studies of the aquifers underlying the areas where wind farms are to be installed, considering the levels of vulnerability and the risks of pollution and alteration of the water supply.

Abstract Wave data collected near the Caribbean coast of Mexico were used to study the frequency and directional structure of the wave field that was generated during the passing of 3 hurricanes. The data were recorded with 2 different acoustic wave gauges, which were installed at a depth of about 20 m. These records provided 183 directional wave spectra corresponding to the occurrence of hurricanes Wilma (October 2005), Dean (August 2007), and Rina (October 2011). The simultaneity of wind waves and swell was detected from different directions, due to the presence of bimodal spectra. For the 3 events, the relation between the translational speed of hurricanes and wave group celerity can explain the presence or absence of spectral bimodality, in either frequency or direction.

Resumen Datos de oleaje recolectados próximos a la costa caribeña de México se utilizaron para estudiar la frecuencia y la estructura direccional del campo de oleaje que se generó como consecuencia del paso de 3 huracanes. Los datos se registraron con 2 equipos acústicos diferentes que miden oleaje, los cuales fueron instalados a una profundidad cercana a los 20 m. Estos registros permitieron obtener 183 espectros direccionales de oleaje, correspondientes a la ocurrencia de los huracanes Wilma (octubre de 2005), Dean (agosto de 2007) y Rina (octubre de 2011). Fue detectada la simultaneidad de oleaje local y remoto procedente de diferentes direcciones, debido a la presencia de espectros bimodales. Para los 3 eventos, se encontró que la relación entre la celeridad de traslación de los huracanes y la celeridad de grupo de los trenes de olas puede explicar la presencia o ausencia de bimodalidad espectral, ya sea en frecuencia o dirección.

Abstract In this paper we present an efficient mode-matching technique to analyze tilted-coil antennas in anisotropic geophysical formations. In this problem, a number of coil antennas with arbitrary relative tilt angle with respect to the symmetry axis are used to radiate electromagnetic fields in a cylindrically layered medium comprised of a metallic mandrel, a borehole, and a surrounding layered Earth formation. This configuration corresponds to that of directional well-logging tools used in oil and gas exploration. Our technique combines closed-form solutions for the Maxwell's Equations in uniaxially anisotropic and radially-stratified cylindrical coordinates with the generalized scattering matrix (GSM) at each axial discontinuity based on the modematching technique. The field from the transmitter tilted-coil source is represented by a set of modal coefficients which, after computation using GSM matrices, are used to compute the transimpedances. We present validation results which show that our technique can efficiently model directional well-logging tools used for oil and gas exploration.

Palaeomagnetic data from Klasies River main site Cave 1 (Eastern Cape Province, South Africa) are reported. Natural remanent magnetisation directions obtained from 77 oriented samples were determined by progressive alternating field demagnetisation methodology. Three palaeomagnetic samplings from the Witness Baulk from the Middle Stone Age (MSA) Late Pleistocene White Sand member and the Holocene Later Stone Age (LSA) middens in Cave 1 were dated and analysed to obtain the palaeomagnetic directions recorded in the sediments. Here we provide new optically stimulated luminescence (OSL) dates for the White Sand Member, and new accelerator mass spectrometry (AMS) radiocarbon dates for the LSA midden of areas not previously dated. The palaeomagnetic analysis took into account rock magnetism and directional analysis. The former reveals that the main magnetic carrier was magnetite; the latter shows that characteristic remanent magnetisation of normal and anomalous directions were observed in the lower portion of the White Sand Member and LSA midden. Normal directions correspond to the palaeosecular variation record for South Africa during the Late Pleistocene. On the other hand, the anomalous directions recorded in the LSA midden might represent the likely Sterno-Etrussia geomagnetic field excursion which occurred during the Late Holocene and is observed in other places on the planet. Finally, the directional data obtained are a potential tool for discussing the age of deposits corresponding to those periods. SIGNIFICANCE: • New dates confirm and extend previous age determinations for the LSA and White Sand Member from Klasies River