Abstract The South American siluriform fishes are found primarily in the Neotropical region, north and east of the Colorado River of Argentina, with a few relict species distributed southward and westward on both sides of the Andes Mountains. Three of these, the closely related trichomycterids Hatcheria macraei, Trichomycterus areolatus and Bullockia maldonadoi, have been subject to historical taxonomic and nomenclatural arrangements. Here, we amplify a 652-bp fragment of COI mtDNA from 55 H. macraei individuals and use publicly available Cytb mtDNA sequences of the three taxa to assess their relationship, genetic variation and haplotype distribution in relation to hydrographic basins. In addition, we extend a recent morphometric study on H. macraei by analyzing body shape in 447 individuals collected from 24 populations across their entire cis-Andean distribution. We identified some lineages previously assigned to T. areolatus that show a closer relationship to either B. maldonadoi or H. macraei, revealing new boundaries to their currently known trans-Andean distribution. We found a great morphologic variation among H. macraei populations and a high genetic variation in H. macraei, T. areolatus and B. maldonadoi associated with river basins. We highlight further integrative studies are needed to enhance our knowledge of the southern Andean trichomycterid diversity.

RESUMEN A partir de los análisis de la cosa perceptiva en la obra de Husserl, se indagará el mundo material como suelo en el cual nuestra vida práctica se sostiene. A partir de sus objeciones al empirismo de Locke, se cuestiona la certeza de la actitud natural sobre la aceptación de una realidad autónoma, para rebatir la noción de un mundo en sí que nos afecta. De este modo, un examen del mundo fenoménico señala que su materia es una dimensión no homogénea ni completa, subrayando una estable variación de las cosas. Con ello, se detecta una ambigüedad esencial según la cual estas se nos ofrecen como apoyo de nuestra praxis.

ABSTRACT From Husserl's analysis of the thing perceived, the material world will be investigated as the ground where our practical life is sustained. From Husserl's objections to Locke's Empiricism, the certainty of the natural attitude about the acceptance of an autonomous reality will be questioned, to refute the notion of a world in itself that affects us. Thus, an examination of the phenomenical world will point out that its matter is a non-homogeneous and non-complete dimension, by stressing a stable variation of things. This will reveal an essential ambiguity, according to which the things are offered to us as support for our praxis.

Resumo A hiperuricemia é comum na doença renal crônica (DRC) e pode estar presente em até 50% dos pacientes que se apresentam para diálise. A hiperuricemia pode ser secundária ao comprometimento da taxa de filtração glomerular (TFG) que ocorre na DRC. No entanto, ela também pode preceder o desenvolvimento da doença renal e mesmo prever uma DRC incidente. Estudos experimentais de modelos hiperuricêmicos descobriram que tanto o ácido úrico solúvel quanto o cristalino podem causar danos renais significativos, caracterizados por isquemia, fibrose tubulointersticial e inflamação. Entretanto, a maioria dos estudos de randomização Mendeliana falhou em demonstrar uma relação causal entre o ácido úrico e a DRC, e os ensaios clínicos têm apresentado resultados variáveis. Aqui sugerimos explicações potenciais para os achados clínicos e genéticos negativos, incluindo o papel do ácido úrico cristalino, do ácido úrico intracelular e da atividade da xantina oxidase na lesão renal mediada por ácido úrico. Propomos ensaios clínicos futuros, bem como um algoritmo para o tratamento de hiperuricemia em pacientes com DRC.

Abstract Hyperuricemia is common in chronic kidney disease (CKD) and may be present in 50% of patients presenting for dialysis. Hyperuricemia can be secondary to impaired glomerular filtration rate (GFR) that occurs in CKD. However, hyperuricemia can also precede the development of kidney disease and predict incident CKD. Experimental studies of hyperuricemic models have found that both soluble and crystalline uric acid can cause significant kidney damage, characterized by ischemia, tubulointerstitial fibrosis, and inflammation. However, most Mendelian randomization studies failed to demonstrate a causal relationship between uric acid and CKD, and clinical trials have had variable results. Here we suggest potential explanations for the negative clinical and genetic findings, including the role of crystalline uric acid, intracellular uric acid, and xanthine oxidase activity in uric acid-mediated kidney injury. We propose future clinical trials as well as an algorithm for treatment of hyperuricemia in patients with CKD.

Abstract The chemical composition and biological activity of the essential oil extracted from the fresh leaves and stem bark of Grewia lasiocarpa was determined for the first time in this study. The essential oils were extracted by hydrodistillation and identified by GC–MS and FTIR. The antibacterial, antioxidant activity and total phenolic content of essential oils were determined. The major compounds identified were phytol (22.6%); α-farnesene (8.62%); n-hexadecanoic acid (7.24%); farnesol (4.61%) in the leaves, and 2-methylheptadecane (7.24%); heptacosane (7.60%); heptadecane, 2,6,10,14-tetramethyl (7.30%). The presence of aromatic, alkanes and phenolic compounds were revealed by FTIR analysis. The in silico oral prediction shows that some of the components are orally safe. The essential oil from the leaves showed cytotoxic activity at 1mg/mL(IC50 =555.70 μg/mL) against HeLa cells. The oils exhibited no significant antioxidant activity (IC50 >1 000 μg/mL) with <100 mg/g GAE of total phenol. The essential oils showed different degrees of activities against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Klebsiella pneumoniae (ATCC 314588) at 10 μg/mL, 5 μg/mL and 2.5 μg/mL. These results might provide a future reference basis for further exploration of more of its medicinal application.

Resumen El artículo muestra la relación estructural entre el testimonio y el juicio estético, y cómo la mentira estructural se implica irreductiblemente como la posibilidad de la verdad. Se explica la necesaria imposibilidad del testimonio como condición de su posibilidad, argumento anticipado por J. L. Borges: “No hay una sola hermosa palabra, con la excepción dudosa de testigo, que no sea una abstracción”. La argumentación se apoya en la teoría husserliana del syncategorema (palabras incompletas cuyo sentido depende del contexto) y en los deícticos (palabras esencialmente ocasionales); asimismo, se toma de I. Kant el papel de la imaginación y los efectos del “como si”.

Abstract This essay demonstrates the structural relationship between testimony and aesthetic judgment. The implications of this discovery are several, the most important being the relationship between the lie and truth, implicating that lie indicates the irreducible possibility of truth. The essay explains the necessary impossibility of the testimony as a condition of its possibility, an argument anticipated in Jorge Luis Borges’ beautiful phrase, “There is not a single beautiful word, with the dubious exception of witness, that is not an abstraction”. The argument is based on Husserl’s theory of the syncategorem (“incomplete” words whose meaning depends on the context) and on deictic words (“essentially occasional” words); as well, it takes from Kant, the role of the imagination and the effects of the “as if”.

ABSTRACT The aim of this study was to develop a preliminary physical map of single nucleotide polymorphisms (SNPs) in alpaca using an alpaca/hamster radiation hybrid panel and a bovine highdensity SNP genotyping microarray (BovineHD BeadChip-Illumina). The methodology included genotyping 92 alpaca/hamster hybrid cell clones, and four control samples (male alpaca, female alpaca, hamster and 1:10 DNAmixture) with the microarray. After genotyping the alpaca and hamster DNA control samples, only bovine SNPs with a call frequency of 1 were retained. The SNPs identified in the alpaca DNA samples were then filtered to remove those also found in the hamster. From the remaining alpaca SNPs, to decrease the probability of false positives, only those with a call frequency from 0.2 to 0.8 in the 92 hybrid clone samples were retained for the final analysis. The remaining alpaca specific SNPs were tabulated in MapMaker format and were analysed with the Carthagene software to identify linkage groups. The linkage groups were mapped to the reference genome Vicugna_pacos-2.0.2, using the BLAST software and the SHORTBLAST command on the Galaxy platform. The two alpaca control samples had 294 165 SNPs with positive signals in the bovine microarray. After eliminating the most common hamster SNPs and the most-likely false positives, 2924 SNPs remained. These were assigned to 33 linkage groups encompassing 216 SNPs. The estimated distance between these SNPs ranged from 65.3 and 671.9 cR, with a logarithm of the odds (LOD) >6.0. Finally, a total of 31 SNPs was found in the reference genome (E-value <0.05).

RESUMEN El objetivo del estudio fue desarrollar un mapa físico preliminar de polimorfismos de nucleótido simple (PNSs) en alpaca usando un panel celular híbrido irradiado alpaca/ hámster y una micromatriz de genotipado de alta densidad de bovino (BovineHD BeadChip-Illumina). Se realizó el genotipado de 92 clones celulares híbridos irradiados y cuatro muestras control (alpaca macho, alpaca hembra, hámster y 1:10 alpaca/hámster mezcla de ADN) con la micromatriz. Luego del genotipaje de las muestras control del ADN de alpaca y hámster solo se retuvieron PNSs de bovinos que mostraron una frecuencia de señal positiva de 1. Los PNSs identificados en el ADN de alpaca fueron filtrados para sustraer los presentes en el hámster. De estos últimos, solo se retuvieron para el análisis final aquellos que tuvieron una frecuencia de señal positiva de 0.2 a 0.8 para los 92 clones y se eliminaron los PNSs que presentaron falsos positivos. Los restantes PNSs específicos de alpaca fueron tabulados en el formato MapMaker y fueron analizados con el programa Carthagene para identificar grupos de ligamiento. Los grupos ligados fueron ubicados en el genoma referencial Vicugna_pacos-2.0.2, aplicando el programa BLAST y el comando SHORTBLAST, en la plataforma Galaxy. Las dos muestras control de alpaca registraron 294 165 PNSs, con señal positiva en la micromatriz de bovino. La cantidad de PNSs de alpaca, después de eliminar los PNSs positivos comunes con hámster, fue 50 686 y luego de eliminar los posibles falsos positivos quedaron 2924 PNSs. Esta cantidad se analizó con el programa Carthagene y resultó en 33 grupos de ligamiento, con un total de 216 PNSs. Las distancias calculadas entre estos PNSs oscilan entre 65.3 y 671.9 cR, con un logaritmo de probabilidades (LOD) >6.0. Finalmente, se encontraron un total de 31 PNSs en el genoma referencial (E-value<0.05).

Resumo Um surto grave de diarreia, associado à baixo crescimento, foi relatado em dez cabritos recém-desmamados, originários de uma fazenda de pesquisa (Grupo A). Dois animais foram submetidos a exame necroscópico. Cinco cabritos da mesma idade e mantidos na mesma instalação não apresentaram sinais clínicos (Grupo B). As características clínicas e as lesões macroscópicas e microscópicas dos animais clinicamente doentes eram consistentes com coccidiose grave. Os animais do grupo A apresentaram níveis significativamente mais baixos de vitamina B12 sérica (<200 pg / ml) em comparação com os animais do grupo B (2000 pg/ml). Além disso, os animais pertencentes ao grupo A apresentaram um número de oocistos de Eimeria arloingi por grama (OPG) de fezes (101,400/g) significativamente mais alto do que os animais do grupo B (9,154/g). As análises microscópica e molecular (genes 18S rRNA e COI) confirmaram que os cabritos estavam infectados com o protozoário E. arloingi. Este estudo fornece uma associação definitiva entre baixos níveis de vitamina B12 no soro e infecção clínica por E. arloingi. Também fornece suporte aos estudos anteriores, que demonstraram como baixos níveis de vitamina B12 no soro comprometem a função dos neutrófilos e, consequentemente, a imunidade a patógenos.

Abstract A severe outbreak of diarrhea associated with poor growth was reported in ten newly weaned goat kids that originated from a research farm (Group A). Two of these kids underwent necropsy examination. Five goat kids of the same age maintained in the same pen showed no clinical signs (Group B). The clinical, gross pathological and histopathological features of the clinically sick animals were consistent with severe coccidiosis. Group A animals had significantly lower levels of serum vitamin B12 (<200 pg/ml) compared with group B animals (2000 pg/ml). In addition, kids belonging to group A had significantly higher Eimeria arloingi oocysts per gram (OPG) of faeces (101,400/g) compared with kids of group B (9,154/g). Microscopy and molecular tools (18S rRNA and COI genes) confirmed that the goat kids were infected with the caprine protozoan parasite E. arloingi. This study provides a definitive association between low levels of serum vitamin B12 and clinical E. arloingi infection, and also provides support to our previous studies that demonstrated how low levels of serum vitamin B12 leads to an impairment of neutrophil function and thereby potential lowered immunity to pathogens.

Abstract: Evolutionary radiations stemming from colonization of archipelagos provide valuable insights into mechanisms and modes of speciation. For this reason, the fauna inhabiting the Galápagos Islands has been the focus of numerous emblematic ecological and evolutionary studies. However, studies focused on rodents have been scarce. Rice rats radiated in situ into at least six endemic species: Aegialomys galapagoensis, Nesoryzomys narboroughi, N. swarthi, N. fernandinae, N. indefessus, and N. darwini. Only the first four species remain extant on the archipelago. These species are considered vulnerable, mainly due to human activities and invasive species. Despite their interesting evolutionary history, questions surrounding phylogenetic relationships, colonization events, genetic diversity and demography of populations remain unresolved. We used the D-loop region of mtDNA to infer phylogenetic relationships, colonization events, date divergences, and conduct population genetic analyses of the four extant endemic species inhabiting the Galápagos Islands. We found that all species were monophyletic. A. galapagoensis is sister to A. xanthaeolus from the continent, and both of them are the sister clade of the genus Nesoryzomys. Our results also showed that there were two colonization events to the islands. The first event was the arrival of the ancestor of Nesoryzomys during the Pliocene, when divergences between genera occurred. The second was Aegialomys during middle Pleistocene, when species diversification began. Populations on each island show high genetic diversity and most show signals of recent expansion. However, future studies are needed to accurately assess the conservation status of these populations. We suggest ongoing monitoring of these vulnerable endemic species, including ecological and population genetic studies. In addition, future studies using genome-wide molecular markers and additional species from the continent, as well as sampling extinct species from the islands, will improve our knowledge about the origin and relationships of the endemic rodents of the Galápagos Islands.

Resumen: Las radiaciones evolutivas que ocurren en los archipiélagos, posterior a su colonización, proporcionan información relevante sobre las formas y mecanismos de especiación. Por tal motivo, la fauna que habita en las Islas Galápagos ha sido objeto de numerosos y emblemáticos estudios. A pesar de lo anterior, los estudios enfocados a roedores han sido escasos. Las ratas arroceras han radiado in situ en al menos seis especies endémicas: Aegialomys galapagoensis, Nesoryzomys narboroughi, N. swarthi, N. fernandinae, N. indefessus y N. darwini. A la fecha, solo las primeras cuatro especies aún se distribuyen en el archipiélago. Dichas especies se encuentran clasificadas como vulnerables, debido principalmente a las actividades humanas y las especies invasoras. A pesar de la interesante historia evolutiva que presentan estas especies, las interrogantes sobre sus relaciones filogenéticas, los eventos de colonización de las islas y la diversidad genética e historia demográfica de sus poblaciones, siguen sin resolverse. Dado lo anterior, usamos la región D-loop del DNA mitocondrial para inferir las relaciones filogenéticas, los eventos de colonización, los tiempos de divergencia y analizar el estado genético poblacional de las cuatro especies endémicas existentes en las Islas Galápagos. Encontramos que todas las especies representan grupos monofiléticos, que A. galapagoensis es la especie hermana de A. xanthaeolus del continente, y que estas dos especies son el grupo hermano del género Nesoryzomys. Nuestros resultados indican dos eventos de colonización en las islas. El primer evento muestra la llegada del ancestro de Nesoryzomys durante el Plioceno, siendo contemporáneo a la divergencia entre los dos géneros. El segundo evento de colonización ocurrió a mediados del Pleistoceno, cuando Aegialomys invadió el archipiélago y los eventos de diversificación de las especies comenzaron. En general, las poblaciones en las islas muestran una diversidad genética alta y una señal de expansión reciente. A pesar de ello, se requiere de más estudios para evaluar con precisión el estado de conservación de las poblaciones. Sugerimos que las poblaciones de estos roedores endémicos y vulnerables sean monitoreadas, realizando estudios ecológicos y genéticos. Adicionalmente, estudios futuros que utilicen marcadores moleculares distribuidos a través del genoma completo y que incluyan a las especies extintas en las islas y a más especies del continente, mejorarían el conocimiento sobre el origen y las relaciones de los roedores endémicos de las Islas Galápagos.

BACKGROUND: HIV prevalence differs substantially between South Africa's provinces, but the factors accounting for this difference are poorly understood OBJECTIVES: To estimate HIV prevalence and incidence trends by province, and to identify the epidemiological factors that account for most of the variation between provinces METHODS: A mathematical model of the South African HIV epidemic was applied to each of the nine provinces, allowing for provincial differences in demography, sexual behaviour, male circumcision, interventions and epidemic timing. The model was calibrated to HIV prevalence data from antenatal and household surveys using a Bayesian approach. Parameters estimated for each province were substituted into the national model to assess sensitivity to provincial variations RESULTS: HIV incidence in 15-49-year-olds peaked between 1997 and 2003 and has since declined steadily. By mid-2013, HIV prevalence in 15-49-year-olds varied between 9.4% (95% CI: 8.5%-10.2%) in Western Cape and 26.8% (95% CI: 25.8%-27.6%) in KwaZulu-Natal. When standardising parameters across provinces, this prevalence was sensitive to provincial differences in the prevalence of male circumcision (range 12.3%-21.4%) and the level of non-marital sexual activity (range 9.5%-24.1%), but not to provincial differences in condom use (range 17.7%-21.2%), sexual mixing (range 15.9%-19.2%), marriage (range 18.2%-19.4%) or assumed HIV prevalence in 1985 (range 17.0%-19.1% CONCLUSION: The provinces of South Africa differ in the timing and magnitude of their HIV epidemics. Most of the heterogeneity in HIV prevalence between South Africa's provinces is attributable to differences in the prevalence of male circumcision and the frequency of non-marital sexual activity

BACKGROUND: The UNAIDS targets for 2020 are to achieve a 90% rate of diagnosis in HIV-positive individuals, to provide antiretroviral treatment (ART) to 90% of HIV-diagnosed individuals and to achieve virological suppression in 90% of ART patients OBJECTIVES: To assess South Africa's progress towards the 2020 targets and variations in performance by province METHODS: A mathematical model was fitted to HIV data for each of South Africa's provinces, and for the country as a whole. Numbers of HIV tests performed in each province were estimated from routine data over the 2002-2015 period, and numbers of patients receiving ART in each province were estimated by fitting models to reported public and private ART enrolment statistics RESULTS: By the middle of 2015, 85.5% (95% CI: 84.5% - 86.5%) of HIV-positive South African adults had been diagnosed, with little variation between provinces. However, only 56.9% (95% CI: 55.3% - 58.7%) of HIV-diagnosed adults were on ART, with this proportion varying between 50.8% in North West and 72.7% in Northern Cape. In addition, 78.4% of adults on ART were virally suppressed, with rates ranging from 69.7% in Limpopo to 85.9% in Western Cape. Overall, 3.39 million (95% CI: 3.26-3.52 million) South Africans were on ART by mid-2015, equivalent to 48.6% (95% CI: 46.0% - 51.2%) of the HIV-positive population. ART coverage varied between 43.0% in Gauteng and 63.0% in Northern Cape CONCLUSION: Although South Africa is well on its way to reaching the 90% HIV diagnosis target, most provinces face challenges in reaching the remaining two 90% targets

Abstract To investigate the evolution and biogeography of an endemic group of South American foxes, we examined mitochondrial DNA control region sequences for 118 individuals belonging to all six extant species of the genus Lycalopex. Phylogenetic and molecular dating analyses supported the inference that this genus has undergone a very recent and rapid radiation, stemming from a common ancestor that lived ca. 1 million years ago. The Brazilian endemic L. vetulus was supported as the most basal species in this genus, whereas the most internal group is comprised by the recently diverged (ca. 350,000 years ago) Andean/Patagonian species L. griseus and L. culpaeus. We discuss the inferred phylogenetic relationships and divergence times in the context of the current geographic distributions of these species, and the likely effects of Pleistocene climatic changes on the biogeography of this group. Furthermore, a remarkable finding was the identification of multiple individuals classified as L. gymnocercus bearing mtDNA haplotypes clearly belonging to L. griseus, sampled in regions where the latter is not known to occur. At a minimum, this result implies the need to clarify the present-day geographic distribution of each of these fox species, while it may also indicate an ongoing hybridization process between them. Future testing of this hypothesis with in-depth analyses of these populations is thus a priority for understanding the history, evolutionary dynamics and present-day composition of this endemic Neotropical genus.

Trachypogon spicatus es una gramínea dominante de algunas sabanas del norte de Suramérica. Su unidad dispersante presenta una arista higroscópica la cual facilita su inserción en irregularidades del suelo, facilitando su ubicación en microhábitats favorables para su establecimiento. Igualmente, se ha sugerido que existe una relación positiva entre la longitud de la arista y la capacidad de entierro de la unidad dispersante. Esta relación incrementa la probabilidad de supervivencia de la semilla ante el fuego al ser el suelo aislante de las altas temperaturas. Se colocaron 192 diásporas de T. spicatus, en bloques aleatorios, en bandejas de sustrato bajo condiciones de invernadero. Luego, se sometieron a cambios de humedad para garantizar el movimiento de la arista y pintaron con aerosol rojo el último día del experimento para determinar la profundidad de entierro. Se evaluó el efecto de la presencia de cariópsis, la longitud de la arista y la presencia de un punto de apoyo para la arista sobre la profundidad de entierro de la diáspora. Se realizó una prueba de sal de Tetrazolio para probar la viabilidad de germinación de 35 cariópsis. No se observaron diferencias significativas en la profundidad de entierro entre diásporas provistas y desprovistas de cariópsis (F(2,126)=0.034, p=0.853). La longitud de la arista parece guardar una relación positiva con la profundidad de entierro únicamente para aquellas unidades dispersantes cuyas aristas no cuentan con un punto de apoyo (r(66)=0.394, p<0.05). Por otro lado, aquellas diásporas cuyas aristas contaban con un punto de apoyo lograron profundidades de entierro significativamente mayores (F(2,126)=7.063, p=0.005). La prueba de viabilidad determinó que 0% de las cariópsis analizadas eran capaces de germinar, esto posiblemente sea debido a la diferencia entre el tiempo de recolección y de prueba. Consideramos que el factor presencia/ausencia de cariópsis era importante ya que había sido ignorado en estudios previos y por la alta producción de diásporas estériles en las gramíneas. Los resultados sugieren que el mecanismo físico que opera sobre la capacidad de entierro de la unidad dispersante de T. spicatus es el torque. Esto explica por qué solo se apoyaron parcialmente las hipótesis propuestas previamente por otros autores, y justifica las diferencias observadas en cuanto a la profundidad de entierro entre unidades dispersantes cuyas aristas contaban o carecían de un punto de apoyo.

Trachypogon spicatus, formerly known as Trachypogon plumosus, is a dominant grass in some savannas of Northern South America. Its dispersal unit, like many other species of the Andropogoneae tribe, bears a hygroscopic awn which facilitates its establishment in favorable microsites. Some authors have previously proposed that there is a positive correlation between awn length and dispersal unit burial, and that this relationship increases the probability of seed survival in the event of a fire, since soil acts as insulator. In this study we experimentally tested this relationship for T. spicatus. A total of 192 diaspores were placed in randomized blocks, in aluminum trays filled with soil under greenhouse conditions. Diaspores were sprayed with water daily for a month to guarantee awn movement; on the last day of the experiment, they were sprayed with red aerosol paint to determine burial depth. The effects of awn length, presence of caryopses, and presence of a pivot for the passive segment of the awn on diaspore burial were evaluated. Germination viability was tested using a tetrazolium salt test for 35 caryopses. No significant differences in diaspore burial were observed between diaspores with and without caryopses (F(2,126)= 0.034, p=0.853). A positive correlation between awn length and diaspore burial was observed only if the passive awn lacked a pivot (r(66)=0.394, p<0.05). Diaspores whose awns had a pivot point achieved significantly deeper burial distances than their counterparts (F(2,126)=7.063, p=0.005). Viability test found that 0% of caryopses tested were able to germinate; this is possibly due to the time difference between sampling and testing. We considered the presence or absence of caryopsis as an important factor, since previous studies have not yet considered it and the high production of sterile diaspores in grasses. These results suggest that the physical mechanism behind T. spicatus diaspore burial is awn torque. This would explain why our results partially support the hypothesis previously proposed by other authors regarding the effect of awn length upon dispersal unit burial, but would also account for the differences observed in burial depth between diaspores with an available pivot point for the passive awn and diaspores lacking thereof. Rev. Biol. Trop. 62 (1): 321-326. Epub 2014 March 01.

This paper focuses on a subset of the practices that have created the powerful learning technology developed and disseminated by Morningside Academy in Seattle, Washington, U.S.A. We briefly describe this technology, known as the Morningside Model of Generative Instruction, and tell how it builds on the selectionist approach of B. F. Skinner and the pragmatic approach of John Dewey. We also describe the critical role Precision Teaching plays at Morningside Academy and its dependence on findings from the science of learning and the science of instruction, including placement of learners, task analysis, content analysis, instructional protocols, and principles of instructional design. Last, we acknowledge the symbiotic relation between effective Direct Instruction programs that teach skills to accuracy levels and Precision Teaching, which takes these accurate repertoires and systematically turns them into high frequency performances that take on the character of fluent repertoires. Over time, using Precision Teaching across multiple and successive repertoires also creates more agile learners.

Este trabajo se enfoca en una serie de prácticas que han creado la poderosa tecnología de aprendizaje desarrollada y diseminada por la Academia Morningside en Seattle, Washington, E. U. Se describe brevemente dicha tecnología, conocida como el Modelo Generativo de Instrucción Morningside y se menciona cómo se construyó bajo la aproximación seleccionista de B. F. Skinner y la aproximación pragmática de John Dewey. También se describe el rol crítico que la Instrucción de Precisión juega en la Academia Morningside y su dependencia en hallazgos de la ciencia del aprendizaje y en la ciencia de la instrucción, incluyendo el papel de los aprendices, el análisis de tareas, el análisis de contenido, los protocolos instruccionales y los principios del diseño instruccional. Finalmente, se reconoce la relación simbiótica entre los programas de Instrucción Directa efectiva, que enseñan habilidades para lograr niveles de precisión y la Enseñanza de Precisión, que considera dichos repertorios precisos y sistemáticamente los convierte en ejecuciones de alta frecuencia que tienen el carácter de repertorios fluidos. Con el paso del tiempo, usar la Enseñanza de Precisión a través de múltiples repertorios sucesivos también crea aprendices más ágiles.

En este artículo se muestra que el estadístico L* de Kullback, para probar la igualdad de varias matrices de correlación, puede ser considerado como un estadístico modificado del test de razón de verosimilitud cuando se muestrean poblaciones normales multivariadas. Derivamos la distribución asintótica nula de L* en series que involucran variables independientes chi-cuadrado, mediante la expansión de L* en términos de otras variables aleatorias y luego invertir la expansión término a término. Se da también un ejemplo para mostrar el procedimiento a ser usado cuando se prueba igualdad de matrices de correlación mediante el estadístico L*.

In this article we show that the Kullbacks statistic for testing equality of several correlation matrices may be considered a modified likelihood ratio statistic when sampling from multivariate normal populations. We derive the asymptotic null distribution of L* in series involving independent chi-square variables by expanding L* in terms of other random variables and then inverting the expansion term by term. An example is also given to exhibit the procedure to be used when testing the equality of correlation matrices using the statistic L\ast.