1,720,986 research outputs found
Evaluation of the affectation of some physical and biological variables in the acoustic detection process of vaquita (Phocoena sinus)
No full textLa vaquita (Phocoena sinus) es una marsopa endémica del Alto Golfo de California y es el mamífero marino en mayor peligro de extinción en el mundo. La principal amenaza para su sobrevivencia es la captura incidental en redes de enmalle. De 2008 a 2019 el Gobierno de México ha invertido un nivel sin precedentes de financiación y esfuerzo para evitar su extinción. Las acciones de conservación han abarcado estrategias para evitar su captura incidental, como vigilancia de actividades ilegales, establecimiento de áreas de prohibición de uso de redes y remoción de redes. Una parte fundamental del plan de recuperación fue la implementación de un programa de monitorización acústica que permitiera indicar la tendencia de la población de vaquita para conocer si los esfuerzos de conservación fueron efectivos. El programa consiste en una red de muestreo con detectores acústicos colocados dentro del Refugio de la Vaquita para grabar sus series de chasquidos de ecolocación y con esta información estimar la tasa de encuentro acústico de vaquita. Aún no se han evaluado todas las variables que pudieran sesgar la tasa de encuentro acústico si no se manejan y modelan de forma adecuada. En este estudio usamos los datos de las temporadas de muestreo de 2011 a 2015 con el objetivo de evaluar la afectación potencial de algunas variables oceanográficas, antropogénicas y biológicas en la detección acústica de vaquita. Para esto se caracterizaron las firmas acústicas que producen los delfines, se identificaron estos eventos en los datos del programa, se caracterizó la distribución de la actividad acústica de los delfines y se analizó las variables que están relacionadas con la detección acústica de vaquita. El modelo final de la ocurrencia acústica de vaquita arrojó como variables predictoras a la interacción de las variables sitios y temporada de muestreo, más la variable presencia de delfines. Por ello, se analizó la interacción espacial y temporal entre delfines y vaquitas durante el periodo de estudio. Dada la función de los chasquidos de ecolocación en los delfines y vaquitas, se infiere que la actividad acústica documentada en los patrones temporales y espaciales de estos cetáceos esta relacionada con la disponibilidad de presas y a que los delfines cambian el comportamiento acústico de vaquita y/o las alejan del sitio de muestreo. Por esta razón, probablemente los patrones de vaquita y de delfines mostraron poco traslape a pesar de tener presas similares y fueron ...The vaquita (Phocoena sinus) is an endemic porpoise to the Upper Gulf of California and is the most endangered marine mammal in the world. Bycatch in gillnets is the main threat of vaquita. From 2008 to 2019, the Government of Mexico has invested an unprecedented level of funding and effort to prevent its extinction. Conservation actions have included strategies to reduce and eliminate bycatch, such as surveillance of illegal activities, the establishment of areas banning the use of gillnets, removal of gillnets, etc. A key part of the vaquita recovery plans was the implementation of an acoustic monitoring program to estimate the population trend of vaquita to know if the conservation efforts have been effective. The program consists of a sampling mesh with autonomous acoustic loggers inside the Vaquita Refuge to record echolocation click trains to be able to estimate the acoustic encounter rate of the vaquita. Not all the variables have been evaluated yet to analyze potential bias in the acoustic detection of the vaquita. In this study, we analyzed data from the sampling seasons 2011 to 215 collected during summers to evaluate the potential impact of some oceanographic, anthropogenic, and biological variables in the acoustic detection of vaquita. To achieve this goal, it was needed to characterize the acoustic signatures produced by the dolphins, identify these events in the database, characterize the distribution of the acoustic activity of the dolphins, and study the variables that are related to the acoustic detection of the vaquita. The final model of the acoustic occurrence of vaquita included as predictor variables the interaction of the sites and sampling season variables, plus the presence of dolphins. Therefore, the spatial and temporal interaction between dolphins and vaquitas was analyzed during the study period. Given the role of echolocation clicks in dolphins and vaquitas, the most likely explanations for the acoustic echolocation activity found in the temporal and spatial patterns of these cetaceans could be related to prey availability, and that the presence of dolphins potentially could change the acoustic behavior of vaquita or move away from the sampling site. For this reason, the vaquita and dolphin patterns probably showed little overlap despite having similar prey, and the patterns were constant in the sampling seasons. Moreover, the sampling season variable was predictive also because the vaquita's acoustic detection rate ..
Social structure of Cuvier’s beaked whale (Ziphius cavirostris) in Guadalupe Island, Baja California, Mexico
No full textEl zifio de Cuvier (Ziphius cavirostris) es una de las especies de zífidos más comunes y de distribución más amplia. Aspectos de su biología y comportamiento, como la estructura social y la genética, han sido poco estudiados. Se sabe que la estructura social influye en la dinámica poblacional de las especies y que poblaciones pequeñas y aisladas tienen mayor probabilidad de tener relaciones de parentesco estrechas. En consecuencia, es mayor la probabilidad de generar endogamia y sufrir depresión endogámica. Se evaluaron la fuerza y la temporalidad de las asociaciones entre individuos y la relación de parentesco por genética de la población. Se realizaron expediciones desde octubre de 2016 hasta octubre de 2021 a la isla Guadalupe en el Pacífico mexicano. Se fotografiaron las aletas dorsales para la foto-identificación y se colectaron biopsias. La diferenciación social, los índices de asociación y los análisis de red se calcularon con el software SOCPROG 2.9. Para el análisis de parentesco se obtuvo el ADN de 30 individuos mediante el método de sales y amplificando por PCR. Se evaluaron 14 microsatélites de cetáceos y la región control mitocondrial. Se encontró una sociedad en donde la mayoría de los individuos no se asociaron entre sí y las asociaciones existentes no fueron fuertes ni estables. En contraste, se encontró evidencia de asociaciones repetitivas de corto plazo y de largo plazo. El parentesco promedio entre los individuos fue bajo y las diadas con valores altos de asociación no tuvieron parentesco cercano. Se detectaron 17 pares de individuos con alto grado de parentesco identificando 13 posibles padres/madres. Se identificaron cinco haplotipos, de los cuales el haplotipo más frecuente en la isla es también el más común en California, EUA, y dos haplotipos que no han sido reportados para otras poblaciones. Existen individuos cuyos alelos y haplotipos son distintos a los de la mayoría. Este trabajo es el primero que realiza análisis sociales y moleculares en conjunto para Z. cavirostris en el mundo.Cuvier’s beaked whale (Ziphius cavirostris) is one of the most common species of beaked whales and the one with the biggest distribution. Behavioral and biological aspects like social structure and genetics in this species are poorly understood. Social structure has an influence in the species populations dynamics and relatedness between individuals is higher in small and isolated populations. In consequence, it´s easier to find inbreeding and inbreeding depression in this kind of populations. Strength and temporality of associations and genetic relatedness between individuals of Guadalupe Island were evaluated. Expeditions to the island were made between October 2016 to October 2021. Photographs of the dorsal fin for photo-id and biopsy samples were taken. Social differentiation, association index and network analysis were calculated using the software SOCPROG 2.9. To assess the relatedness DNA was obtained from 30 individuals using a salt method and PCR amplification. 14 cetacean microsatellites and mitochondrial control region were calculated. Most individuals do not tend to associate and most of the associations were weak and unstable. Nevertheless, there is evidence of repetitive short and long-term associations. Relatedness between individuals was low and pairs of individuals with high association values were not genetically related. 17 pairs of individuals with high degree of relatedness were found, including 13 possible parents. From the five identified haplotypes, the most frequent one in the island is also the most frequent in California, USA and two haplotypes were not registered before. Some individuals have alleles and haplotypes different from the resto of the population. This work is the first one to assess social structure and relatedness together for Z, cavirostris in the world
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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