Introducción a la geografía histórica

La obra de Sauer abre paso a la formación del saber ambiental de nuestro tiempo y contribuye a su desarrollo en América Latina. El artículo sigue una serie de temas profundizados por el autor, y concluye  recordándonos que el aterrador impacto del moderno mundo Occidental, no cancela la verdad de que el la historia del hombre ha sido marcadamente pluralista, y que no existen leyes generales de la sociedad, sino únicamente acuerdos culturales.L’œuvre de Sauer ouvre la voie à la formation d’un savoir environnemental de notre temps et contribue à son développement en Amérique latine. L’article poursuit une série de thèmes approfondis par l’auteur, et conclut en nous rappelant que l’épouvantable impact du monde moderne Occidental, n’annule point la vérité que l’histoire de l’homme a toujours été pluraliste, et qu’il n’existe point de lois générales de la société mais uniquement des accords culturels.Sauer's work opens the way for the formation of environmental knowledge of our time and contribute to its development in Latin America. The article continues a series of topics in depth by the author, and concludes by reminding us that the terrifying impact of modern Western world, does not cancel the truth that human history has been remarkably pluralistic, and there are no general laws of society, but only cultural agreements

Introducción a la geografía histórica

La obra de Sauer abre paso a la formación del saber ambiental de nuestro tiempo y contribuye a su desarrollo en América Latina. El artículo sigue una serie de temas profundizados por el autor, y concluye  recordándonos que el aterrador impacto del moderno mundo Occidental, no cancela la verdad de que el la historia del hombre ha sido marcadamente pluralista, y que no existen leyes generales de la sociedad, sino únicamente acuerdos culturales.L’œuvre de Sauer ouvre la voie à la formation d’un savoir environnemental de notre temps et contribue à son développement en Amérique latine. L’article poursuit une série de thèmes approfondis par l’auteur, et conclut en nous rappelant que l’épouvantable impact du monde moderne Occidental, n’annule point la vérité que l’histoire de l’homme a toujours été pluraliste, et qu’il n’existe point de lois générales de la société mais uniquement des accords culturels.Sauer's work opens the way for the formation of environmental knowledge of our time and contribute to its development in Latin America. The article continues a series of topics in depth by the author, and concludes by reminding us that the terrifying impact of modern Western world, does not cancel the truth that human history has been remarkably pluralistic, and there are no general laws of society, but only cultural agreements

La morfología del paisaje

Artículo publicado en 1925, en el cual el autor persigue definir el campo de la geografía en cuanto disciplina científica como un cuerpo organizado de conocimientos, cuya tarea es la de establecer un sistema crítico que abarque la fenomenología del paisaje, con el propósito de aprehender en todo su significado y color la variedad de la escena terrestre, buscando organizar los campos de la geografía como ciencia positiva.Article publié en 1925, dans lequel l’auteur persiste à définir le champ de la géographie en tant que discipline scientifique comme un corps organisé de connaissances, dont la tâche consiste à établir un système critique qui couvre la phénoménologie du paysage, avec pour objectif d’appréhender dans toute sa signification et couleur la variété de la scène terrestre, recherchant à organiser les champs de la géographie comme science positive.Article published in 1925, in which the author pursues the definition of the field of geography as a scientific discipline with an organized body of knowledge, whose task is to establish a critical system which should include the phenomenology of the landscape, in order to apprehend in all its meaning and color the variety of the terrestrial scene, in the purpose of organizing the field of geography as a positive science

La morfología del paisaje

Artículo publicado en 1925, en el cual el autor persigue definir el campo de la geografía en cuanto disciplina científica como un cuerpo organizado de conocimientos, cuya tarea es la de establecer un sistema crítico que abarque la fenomenología del paisaje, con el propósito de aprehender en todo su significado y color la variedad de la escena terrestre, buscando organizar los campos de la geografía como ciencia positiva.Article publié en 1925, dans lequel l’auteur persiste à définir le champ de la géographie en tant que discipline scientifique comme un corps organisé de connaissances, dont la tâche consiste à établir un système critique qui couvre la phénoménologie du paysage, avec pour objectif d’appréhender dans toute sa signification et couleur la variété de la scène terrestre, recherchant à organiser les champs de la géographie comme science positive.Article published in 1925, in which the author pursues the definition of the field of geography as a scientific discipline with an organized body of knowledge, whose task is to establish a critical system which should include the phenomenology of the landscape, in order to apprehend in all its meaning and color the variety of the terrestrial scene, in the purpose of organizing the field of geography as a positive science

Engrailed (Gln50→Lys) homeodomain–DNA complex at 1.9 Å resolution: structural basis for enhanced affinity and altered specificity

AbstractBackground: The homeodomain is one of the key DNA-binding motifs used in eukaryotic gene regulation, and homeodomain proteins play critical roles in development. The residue at position 50 of many homeodomains appears to determine the differential DNA-binding specificity, helping to distinguish among binding sites of the form TAATNN. However, the precise role(s) of residue 50 in the differential recognition of alternative sites has not been clear. None of the previously determined structures of homeodomain–DNA complexes has shown evidence for a stable hydrogen bond between residue 50 and a base, and there has been much discussion, based in part on NMR studies, about the potential importance of water-mediated contacts. This study was initiated to help clarify some of these issues.Results: The crystal structure of a complex containing the engrailed Gln50→Lys variant (QK50) with its optimal binding site TAATCC (versus TAATTA for the wild-type protein) has been determined at 1.9 Å resolution. The overall structure of the QK50 variant is very similar to that of the wild-type complex, but the sidechain of Lys50 projects directly into the major groove and makes several hydrogen bonds to the O6 and N7 atoms of the guanines at base pairs 5 and 6. Lys50 also makes an additional water-mediated contact with the guanine at base pair 5 and has an alternative conformation that allows a hydrogen bond with the O4 of the thymine at base pair 4.Conclusions: The structural context provided by the folding and docking of the engrailed homeodomain allows Lys50 to make remarkably favorable contacts with the guanines at base pairs 5 and 6 of the binding site. Although many different residues occur at position 50 in different homeodomains, and although numerous position 50 variants have been constructed, the most striking examples of altered specificity usually involve introducing or removing a lysine sidechain from position 50. This high-resolution structure also confirms the critical role of Asn51 in homeodomain–DNA recognition and further clarifies the roles of water molecules near residues 50 and 51

Landscape science: a Russian geographical tradition

The Russian geographical tradition of landscape science (landshaftovedenie) is analyzed with particular reference to its initiator, Lev Semenovich Berg (1876-1950). The differences between prevailing Russian and Western concepts of landscape in geography are discussed, and their common origins in German geographical thought in the late nineteenth and early twentieth centuries are delineated. It is argued that the principal differences are accounted for by a number of factors, of which Russia's own distinctive tradition in environmental science deriving from the work of V. V. Dokuchaev (1846-1903), the activities of certain key individuals (such as Berg and C. O. Sauer), and the very different social and political circumstances in different parts of the world appear to be the most significant. At the same time it is noted that neither in Russia nor in the West have geographers succeeded in specifying an agreed and unproblematic understanding of landscape, or more broadly in promoting a common geographical conception of human-environment relationships. In light of such uncertainties, the latter part of the article argues for closer international links between the variant landscape traditions in geography as an important contribution to the quest for sustainability

Burkholderia Type VI Secretion Systems Have Distinct Roles in Eukaryotic and Bacterial Cell Interactions

Bacteria that live in the environment have evolved pathways specialized to defend against eukaryotic organisms or other bacteria. In this manuscript, we systematically examined the role of the five type VI secretion systems (T6SSs) of Burkholderia thailandensis (B. thai) in eukaryotic and bacterial cell interactions. Consistent with phylogenetic analyses comparing the distribution of the B. thai T6SSs with well-characterized bacterial and eukaryotic cell-targeting T6SSs, we found that T6SS-5 plays a critical role in the virulence of the organism in a murine melioidosis model, while a strain lacking the other four T6SSs remained as virulent as the wild-type. The function of T6SS-5 appeared to be specialized to the host and not related to an in vivo growth defect, as ΔT6SS-5 was fully virulent in mice lacking MyD88. Next we probed the role of the five systems in interbacterial interactions. From a group of 31 diverse bacteria, we identified several organisms that competed less effectively against wild-type B. thai than a strain lacking T6SS-1 function. Inactivation of T6SS-1 renders B. thai greatly more susceptible to cell contact-induced stasis by Pseudomonas putida, Pseudomonas fluorescens and Serratia proteamaculans—leaving it 100- to 1000-fold less fit than the wild-type in competition experiments with these organisms. Flow cell biofilm assays showed that T6S-dependent interbacterial interactions are likely relevant in the environment. B. thai cells lacking T6SS-1 were rapidly displaced in mixed biofilms with P. putida, whereas wild-type cells persisted and overran the competitor. Our data show that T6SSs within a single organism can have distinct functions in eukaryotic versus bacterial cell interactions. These systems are likely to be a decisive factor in the survival of bacterial cells of one species in intimate association with those of another, such as in polymicrobial communities present both in the environment and in many infections

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts