Nosso cérebro é como 100 bilhões de minicomputadores todos funcionando sincronizados: mero acaso, fortuita necessidade ou design inteligente???

Cell
Article| Volume 175, ISSUE 3, P643-651.e14, October 18, 2018


Enhanced Dendritic Compartmentalization in Human Cortical Neurons

Lou Beaulieu-Laroche, Enrique H.S. Toloza, Marie-Sophie van der Goes, Matthew P. Frosch, Sydney S. Cash, Mark T. Harnett5

Show footnotes

DOI: https://doi.org/10.1016/j.cell.2018.08.045

 

Source/Fonte: New Scientist

Highlights

• Direct electrical recordings to compare human and rat cortical dendrites
• Longer human dendrites exhibit increased electrical compartmentalization
• Reduced ion channel densities in human dendrites
• Compartmentalization alters the input-output properties of human neurons

Summary

The biophysical features of neurons shape information processing in the brain. Cortical neurons are larger in humans than in other species, but it is unclear how their size affects synaptic integration. Here, we perform direct electrical recordings from human dendrites and report enhanced electrical compartmentalization in layer 5 pyramidal neurons. Compared to rat dendrites, distal human dendrites provide limited excitation to the soma, even in the presence of dendritic spikes. Human somas also exhibit less bursting due to reduced recruitment of dendritic electrogenesis. Finally, we find that decreased ion channel densities result in higher input resistance and underlie the lower coupling of human dendrites. We conclude that the increased length of human neurons alters their input-output properties, which will impact cortical computation.

FREE PDF GRATIS: Cell

Campanha de Bolsonaro aplica seu próprio viés político à educação???

“Quando você iguala ciência e ideologia, você anda para trás, ignora séculos de aprendizado”, diz Luiz Davidovich, presidente da Academia Brasileira de Ciências. “A teoria da evolução não é ideológica. É resultado de percepções científicas e foi testada ao longo do tempo.”

in Campanha de Bolsonaro aplica seu próprio viés político à educação.

Davidovich cometeu dois erros:

1. A teoria da evolução é sim ideológica - quem disse foi Darwin em uma de suas cartas que pelo menos ele tinha dado um chega pra lá no criacionismo; 

2. A teoria da evolução foi testada em nível microevolutivo, macroevolutivo, não! A descendência com modificação ao longo do tempo, por exemplo. Nunca explicaram a Explosão Cambriana. Quais são os mecanismos evolucionários? De A a Z? Qual a origem da informação genética? Por que do upgrade para a Síntese Evolutiva Ampliada/Estendida com aspectos neolamarckistas porque a Síntese Evolutiva Moderna já era em 1980 uma teoria científica falida que posava de ortodoxia científica somente nos livros-texto??? 

Sim, a teoria da evolução deve continuar sendo ensinada em nossas escolas, mas deve ser ensinada objetiva e honestamente considerando as evidências a favor e contra. Do jeito que a teoria da evolução é ensinada no Brasil, não é educação, mas doutrinação ideológica do materialismo filosófico que posa como se fosse ciência!

Como a geologia conta a história dos gargalos evolutivos e da vida na Terra

AstrobiologyVol. 18, No. 9 Hypothesis ArticlesFree Access
Geological and Geochemical Constraints on the Origin and Evolution of Life
Norman H. Sleep
Published Online:12 Sep 2018 https://doi.org/10.1089/ast.2017.1778

 

 Source/Fonte: Nature - NASA

Abstract

The traditional tree of life from molecular biology with last universal common ancestor (LUCA) branching into bacteria and archaea (though fuzzy) is likely formally valid enough to be a basis for discussion of geological processes on the early Earth. Biologists infer likely properties of nodal organisms within the tree and, hence, the environment they inhabited. Geologists both vet tenuous trees and putative origin of life scenarios for geological and ecological reasonability and conversely infer geological information from trees. The latter approach is valuable as geologists have only weakly constrained the time when the Earth became habitable and the later time when life actually existed to the long interval between ∼4.5 and ∼3.85 Ga where no intact surface rocks are known. With regard to vetting, origin and early evolution hypotheses from molecular biology have recently centered on serpentinite settings in marine and alternatively land settings that are exposed to ultraviolet sunlight. The existence of these niches on the Hadean Earth is virtually certain. With regard to inferring geological environment from genomics, nodes on the tree of life can arise from true bottlenecks implied by the marine serpentinite origin scenario and by asteroid impact. Innovation of a very useful trait through a threshold allows the successful organism to quickly become very abundant and later root a large clade. The origin of life itself, that is, the initial Darwinian ancestor, the bacterial and archaeal roots as free-living cellular organisms that independently escaped hydrothermal chimneys above marine serpentinite or alternatively from shallow pore-water environments on land, the Selabacteria root with anoxygenic photosynthesis, and the Terrabacteria root colonizing land are attractive examples that predate the geological record. Conversely, geological reasoning presents likely events for appraisal by biologists. Asteroid impacts may have produced bottlenecks by decimating life. Thermophile roots of bacteria and archaea as well as a thermophile LUCA are attractive.

FREE PDF GRATIS: Astrobiology  

O problema cosmológico do lítio: uma das incógnitas na descrição atual do Big Bang

$7\mathrm{Be}(n,p)7\mathrm{Li}$ Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN

L. Damone et al. (The n_TOF Collaboration [www.cern.ch/ntof])

Phys. Rev. Lett. 121, 042701 – Published 24 July 2018

Abstract

We report on the measurement of the $7\mathrm{Be}(n,p)7\mathrm{Li}$ cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and they showed a large discrepancy between each other. The measurement was performed with a Si telescope and a high-purity sample produced by implantation of a $7\mathrm{Be}$ ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low energy, relative to current evaluations, in the region of BBN interest, the present results are consistent with the values inferred from the time-reversal $7\mathrm{Li}\left(p,n\right)7\mathrm{Be}$ reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near-threshold neutron production in the $p+7\mathrm{Li}$ reaction is also discussed.

• Revised 9 May 2018
• Received 16 March 2018

DOI: https://doi.org/10.1103/PhysRevLett.121.042701

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH) 

1. Research Areas

Big bang nucleosynthesis Nuclear reactions Nucleon induced nuclear reactions

Gravitation, Cosmology & Astrophysics Nuclear Physics

FREE PDF GRATIS: Phys Rev Let Sup Info

Being Modern - The Cultural Impact of Science in the Early Twentieth Century

Being Modern: The Cultural Impact of Science in the Early Twentieth Century

Robert Bud, Paul Greenhalgh, Frank James and Morag Shiach | October 2018

Format: 234x156mm
 

Open Access PDF
ISBN: 978-1-78735-393-0
FREE
 

Hardback
ISBN: 978-1-78735-395-4
£50.00
 

Paperback
ISBN: 978-1-78735-394-7
£30.00
 

Pages: 438

About the book

In the early decades of the twentieth century, engagement with science was commonly used as an emblem of modernity. This phenomenon is now attracting increasing attention in different historical specialties. Being Modern builds on this recent scholarly interest to explore engagement with science across culture from the end of the nineteenth century to approximately 1940.

Addressing the breadth of cultural forms in Britain and the western world from the architecture of Le Corbusier to working class British science fiction, Being Modern paints a rich picture. Seventeen distinguished contributors from a range of fields including the cultural study of science and technology, art and architecture, English culture and literature examine the issues involved. The book will be a valuable resource for students, and a spur to scholars to further examination of culture as an interconnected web of which science was a critical part, and to supersede such tired formulations as 'Science and culture'.
About the editors

Robert Bud is Research Keeper at the Science Museum in London. His award-winning publications in the history of science include studies of biotechnology and scientific instruments. Paul Greenhalgh is Director of the Sainsbury Centre at the University of East Anglia, and Professor of Art History there. He has published extensively in the history of art, design, and the decorative arts in the early modern period. Frank James is Professor of History of Science at the Royal Institution and University College London. His research formerly centred on Faraday, but now focuses on Davy. Morag Shiach is Professor of Cultural History at Queen Mary University of London. She has published extensively on the cultural history of modernism and on modernism and labour. 

Table of contents Being Modern: Introduction
Robert Bud and Morag Shiach

Section 1: Science, modernity and culture

1 Multiple modernisms in concert: the sciences, technology and culture in Vienna around 1900
Mitchell G. Ash 

2 The cinematic sound of industrial modernity: first notes
Tim Boon

3 Woolf’s atom, Eliot’s catalyst and Richardson’s waves of light: science and modernism in 1919
Morag Shiach 

4 T.S. Eliot: modernist literature, disciplines and the systematic pursuit of knowledge
Kevin Brazil

Section 2: Tensions over science 

5 Modernity and the ambivalent significance of applied science: motors, wireless, telephones and poison gas
Robert Bud 

6 ‘The springtime of science’: modernity and the future and past of science
Frank A.J.L. James 

7 ‘Come on you demented modernists, let’s hear from you’: science fans as literary critics in the 1930s
Charlotte Sleigh

Section 3: Mathematics and physics 

8 Modern by numbers: modern mathematics as a model for literary modernism
Nina Engelhardt 

9 Sculpture in the Belle Epoque: mathematics, art and apparitions in school and gallery
Lewis Pyenson 

10 Architecture, science and purity
Judi Loach

11 A Portrait of the Scientist as a Young Ham: wireless, modernity and interwar nuclear physics
Jeff Hughes 

12 Whose modernism, whose speed? Designing mobility for the future, 1880s–1945
Ruth Oldenziel 

Section 4: Life, biology and the organicist metaphor 

13 Ludwig Koch’s birdsong on wartime BBC radio: knowledge, citizenship and solace
Michael Guida 

14 ‘More Modern than the Moderns’: performing cultural evolution in the Kibbo Kift Kindred
Annebella Pollen 

15 Organicism and the modern world: from A.N. Whitehead to Wyndham Lewis and D.H. Lawrence
Craig Gordon 

16 Liquid crystal as chemical form and model of thinking in Alfred Döblin’s modernist science
Esther Leslie 

17 ‘I am attracted to the natural order of things’: Le Corbusier’s rejection of the machine
Tim Benton 

Epilogue: Science after modernity
Frank A.J.L. James and Robert Bud

Select bibliography
Index 

 

FREE PDF GRATIS: UCL Press

Clusters de cromossomos ajudam a manter o genoma unido: mero acaso, fortuita necessidade ou design inteligente?

A conserved function for pericentromeric satellite DNA

Madhav Jagannathan, Ryan Cummings, Yukiko M Yamashita

University of Michigan, United States

Research Article Mar 26, 2018 

Source/Fonte: The Scientist

 

Abstract


A universal and unquestioned characteristic of eukaryotic cells is that the genome is divided into multiple chromosomes and encapsulated in a single nucleus. However, the underlying mechanism to ensure such a configuration is unknown. Here, we provide evidence that pericentromeric satellite DNA, which is often regarded as junk, is a critical constituent of the chromosome, allowing the packaging of all chromosomes into a single nucleus. We show that the multi-AT-hook satellite DNA-binding proteins, Drosophila melanogaster D1 and mouse HMGA1, play an evolutionarily conserved role in bundling pericentromeric satellite DNA from heterologous chromosomes into ‘chromocenters’, a cytological association of pericentromeric heterochromatin. Defective chromocenter formation leads to micronuclei formation due to budding from the interphase nucleus, DNA damage and cell death. We propose that chromocenter and satellite DNA serve a fundamental role in encapsulating the full complement of the genome within a single nucleus, the universal characteristic of eukaryotic cells.  

 

https://doi.org/10.7554/eLife.34122.001
 

eLife Digest


On Earth, life is divided into three domains. The smallest of these domains includes all the creatures, from sunflowers to yeasts to humans, that have the genetic information within their cells encased in a structure known as the nucleus. The genomes of these organisms are formed of long pieces of DNA, called chromosomes, which are packaged tightly and then unpackaged every time the cell divides. When a cell is not dividing, the chromosomes in the nucleus are loosely bundled up together.

It is well known that DNA is the blueprint for the building blocks of life, but actually most of the genetic information in a cell codes for nothing, and has unknown roles. An example of such ‘junk DNA’ is pericentrometric satellite DNA, small repetitive sequences found on all chromosomes.

However, new experiments by Jagannathan et al. show that, in the nucleus of animal cells, certain DNA binding proteins make chromosomes huddle together by attaching to multiple pericentrometric satellite DNA sequences on different chromosomes. In fact, if these proteins are removed from mice and fruit flies cells grown in the laboratory, the chromosomes cannot be clustered together. Instead, they ‘float away’, and the membranes of the nucleus get damaged, possibly buckling under the pressure of the unorganized DNA.

These events damage the genetic information, which can lead to the cell dying or forming tumors. ‘Junk DNA’ therefore appears to participate in fundamental cellular processes across species, a result that opens up several new lines of research.  

 

https://doi.org/10.7554/eLife.34122.002 

 

FREE PDF GRATIS: eLIFE

Teoria das cordas: a energia escura é permitida mesmo?

de Sitter swampland conjecture and the Higgs potential

Frederik Denef, Arthur Hebecker, and Timm Wrase

Phys. Rev. D 98, 086004 – Published 2 October 2018

 

Source/Fonte

Abstract

According to a conjecture recently put forward in [1], the scalar potential $V$ of any consistent theory of quantum gravity satisfies a bound $|\nabla V|/V\ge O\left(1\right)$. This forbids de Sitter solutions and supports quintessence models of cosmic acceleration. Here, we point out that in the simplest models incorporating the standard model in addition to quintessence, with the two sectors decoupled as suggested by observations, the proposed bound is violated by 50 orders of magnitude. However, a very specific coupling between quintessence and just the Higgs sector may still be allowed and consistent with the conjecture.

• Received 7 August 2018

DOI: https://doi.org/10.1103/PhysRevD.98.086004

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society

FREE PDF GRATIS: Phys Rev D

Existe um paradigma darwinista? Por uma ontologia histórica da teoria da evolução

Existe-t-il un paradigme darwinien? Pour une ontologie historique de la théorie de l’évolution
 

Nicola Bertoldi Université de Paris 1 - Panthéon Sorbonne
DOI: https://doi.org/10.20416/lsrsps.v5i1.8
 

Mots-clés: histoire et philosophie de la biologie, théorie de l’évolution, paradigme, Thomas Kuhn, ontologie historique 

 

Source/Fonte: New Scientist

Résumé

La théorie de Darwin est considérée par de nombreux historiens comme une véritable révolution scientifique, raison pour laquelle l’objectif de cet article est précisément de rendre compte des caractères révolutionnaires de cette théorie, dans le cadre d’une conception des révolutions scientifiques empruntée à l’œuvre de Thomas Kuhn. Cela implique, notamment, la définition d’un « paradigme darwinien », à la fois comme matrice disciplinaire et comme solution exemplaire à un problème donné. Dans un tel but, nous définirons la structure et le contenu de la théorie de Darwin, afin de mettre au jour la problématique qui pourrait être à la base d’un « paradigme darwinien », c’est-à-dire le problème de la complexité adaptative du vivant. Nous identifierons ensuite ce qui distinguerait ce paradigme des autres, si bien que le problème de la complexité ne saurait être posé et résolu que dans son cadre. Pour ce faire, nous nous concentrerons sur deux dichotomies : d’une part, celle entre fonctionnalisme et formalisme, d’autre part, celle entre naturalisme et idéalisme. En conclusion, nous mettrons au jour les limites de l’épistémologie kuhnienne pour l’analyse de la théorie de l’évolution, ce qui nous amènera à equisser les contours d’une approche alternative, que nous appellerons « ontologie historique ».
 

FREE PDF GRATIS: Lato Sensu

Darwin, as teorias bem estabelecidas de padrões na evolução podem estar erradas

History is written by the victors: The effect of the push of the past on the fossil record

Graham E. Budd Richard P. Mann

First published: 26 September 2018 https://doi.org/10.1111/evo.13593

Abstract

Survivorship biases can generate remarkable apparent rate heterogeneities through time in otherwise homogeneous birth‐death models of phylogenies. They are a potential explanation for many striking patterns seen in the fossil record and molecular phylogenies. One such bias is the “push of the past”: clades that survived a substantial length of time are likely to have experienced a high rate of early diversification. This creates the illusion of a secular rate slow‐down through time that is, rather, a reversion to the mean. An extra effect increasing early rates of lineage generation is also seen in large clades. These biases are important but relatively neglected influences on many aspects of diversification patterns in the fossil record and elsewhere, such as diversification spikes after mass extinctions and at the origins of clades; they also influence rates of fossilization, changes in rates of phenotypic evolution and even molecular clocks. These inevitable features of surviving and/or large clades should thus not be generalized to the diversification process as a whole without additional study of small and extinct clades, and raise questions about many of the traditional explanations of the patterns seen in the fossil record.

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