A teoria da relatividade de Einstein - Infográfico

No limiar de uma nova revolução nas ciência da vida: mudança paradigmática, mas só em 2020

World J Biol Chem. May 26, 2013; 4(2): 13–15.

Published online May 26, 2013. doi: 10.4331/wjbc.v4.i2.13

PMCID: PMC3654106

At the dawn of a new revolution in life sciences

František Baluška and Guenther Witzany

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Abstract

In a recently published article Sydney Brenner argued that the most relevant scientific revolution in biology at his time was the breakthrough of the role of “information” in biology. The fundamental concept that integrates this new biological “information” with matter and energy is the universal Turing machine and von Neumann’s self-reproducing machines. In this article we demonstrate that in contrast to Turing/von Neumann machines living cells can really reproduce themselves. Additionally current knowledge on the roles of non-coding RNAs indicates a radical violation of the central dogma of molecular biology and opens the way to a new revolution in life sciences.

Keywords: History of science, Paradigm shift, Information, Non-coding RNAs

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NOTA DESTE BLOGGER:

A Nomenklatura científica e a Galera dos meninos e meninas de Darwin negam veementemente que não existe crise na atual teoria da evolução de Darwin através da seleção natural e n mecanismos evolucionários (de A a Z, vai que um falhe...) quando uma montanha de evidências encontradas nas pesquisas e artigos na literatura especializada mostram a quase total falência da Síntese Evolutiva Moderna no contexto de justificação teórica. Eis aqui mais artigo mostrando a inadequação do neodarwinismo e da necessidade de uma mudança paradigmática em biologia evolucionária.

Qual é mesmo a teoria científica que no seu arcabouço teórico lida com INFORMAÇÃO? Qual? Qual mesmo? Eu não ouvi! Ah, a teoria do Design Inteligente!

Fui, nem sei por que, cada vez mais feliz quando os próprios evolucionistas vindicam a turma do Design Inteligente, essa turma que não sabe o que é ciência, não faz ciência, são pseudocientistas, criacionistas disfarçados y otras cositas mais.

Pano rápido, pois Darwin Kaput!!!

A comida dos neandertais: uma nova perspectiva usando biomarcadores fecais

The Neanderthal Meal: A New Perspective Using Faecal Biomarkers

Ainara Sistiaga mail, Carolina Mallol, Bertila Galván, Roger Everett Summons

Published: June 25, 2014DOI: 10.1371/journal.pone.0101045

Abstract

Neanderthal dietary reconstructions have, to date, been based on indirect evidence and may underestimate the significance of plants as a food source. While zooarchaeological and stable isotope data have conveyed an image of Neanderthals as largely carnivorous, studies on dental calculus and scattered palaeobotanical evidence suggest some degree of contribution of plants to their diet. However, both views remain plausible and there is no categorical indication of an omnivorous diet. Here we present direct evidence of Neanderthal diet using faecal biomarkers, a valuable analytical tool for identifying dietary provenance. Our gas chromatography-mass spectrometry results from El Salt (Spain), a Middle Palaeolithic site dating to ca. 50,000 yr. BP, represents the oldest positive identification of human faecal matter. We show that Neanderthals, like anatomically modern humans, have a high rate of conversion of cholesterol to coprostanol related to the presence of required bacteria in their guts. Analysis of five sediment samples from different occupation floors suggests that Neanderthals predominantly consumed meat, as indicated by high coprostanol proportions, but also had significant plant intake, as shown by the presence of 5β-stigmastanol. This study highlights the applicability of the biomarker approach in Pleistocene contexts as a provider of direct palaeodietary information and supports the opportunity for further research into cholesterol metabolism throughout human evolution.

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Primeiro Congresso Brasileiro de Design Inteligente

Reserve essas datas: 14-16 de novembro de 2014.
Local: The Royal Plaza, Campinas, SP.

Correção aparente à velocidade da luz em um potencial gravitacional

Apparent Correction to the Speed of Light in a Gravitational Potential

J. D. Franson

(Submitted on 28 Nov 2011 (v1), last revised 3 Apr 2014 (this version, v6))

The effects of physical interactions are usually incorporated into the quantum theory by including the corresponding terms in the Hamiltonian. Here we consider the effects of including the gravitational potential energy of massive particles in the Hamiltonian of quantum electrodynamics. This results in a predicted correction to the speed of light that is proportional to the fine structure constant. The correction to the speed of light obtained in this way depends on the gravitational potential and not the gravitational field, which is not gauge invariant and presumably nonphysical. Nevertheless, the predicted results are in reasonable agreement with experimental observations from Supernova 1987a.

Comments: 25 pages, 6 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)

Journal reference: New Journal of Physics 16, 065008 (2014)

Cite as: arXiv:1111.6986 [hep-ph]

(or arXiv:1111.6986v6 [hep-ph] for this version)

Submission history

From: James Franson [view email] 

[v1] Mon, 28 Nov 2011 19:40:42 GMT (387kb)

[v2] Tue, 13 Dec 2011 18:26:11 GMT (387kb)

[v3] Fri, 17 Feb 2012 19:10:22 GMT (391kb)

[v4] Mon, 11 Jun 2012 16:51:56 GMT (390kb)

[v5] Mon, 23 Dec 2013 15:42:57 GMT (884kb)

[v6] Thu, 3 Apr 2014 17:31:55 GMT (941kb)

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Estrutura e função do motor bidirecional do flagelo bacteriano que Darwin não explica!

Biomolecules 2014, 4(1), 217-234; doi:10.3390/biom4010217

Review

Structure and Function of the Bi-Directional Bacterial Flagellar Motor

Yusuke V. Morimoto 1,2 and Tohru Minamino 2,*

1 Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan; E-Mail: ymorimoto@fbs.osaka-u.ac.jp

2 Graduate School of Frontier Biosciences, Osaka University 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan

* Author to whom correspondence should be addressed; E-Mail: tohru@fbs.osaka-u.ac.jp; Tel: +81-6-6879-4625; Fax: +81-6-6879-4652.

Received: 30 December 2013; in revised form: 24 January 2014 / Accepted: 4 February 2014 / 

Published: 18 February 2014

Abstract: 

The bacterial flagellum is a locomotive organelle that propels the bacterial cell body in liquid environments. The flagellum is a supramolecular complex composed of about 30 different proteins and consists of at least three parts: a rotary motor, a universal joint, and a helical filament. The flagellar motor of Escherichia coli and Salmonella enterica is powered by an inward-directed electrochemical potential difference of protons across the cytoplasmic membrane. The flagellar motor consists of a rotor made of FliF, FliG, FliM and FliN and a dozen stators consisting of MotA and MotB. FliG, FliM and FliN also act as a molecular switch, enabling the motor to spin in both counterclockwise and clockwise directions. Each stator is anchored to the peptidoglycan layer through the C-terminal periplasmic domain of MotB and acts as a proton channel to couple the proton flow through the channel with torque generation. Highly conserved charged residues at the rotor–stator interface are required not only for torque generation but also for stator assembly around the rotor. In this review, we will summarize our current understanding of the structure and function of the proton-driven bacterial flagellar motor.

Keywords: Bacterial flagellum; rotary motor; motility; stator; rotor; torque generation; mechanosensor

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Uma bússola magnética ajuda a migração das borboletas Monarca

A magnetic compass aids monarch butterfly migration

Patrick A Guerra, Robert J Gegear & Steven M Reppert

AffiliationsContributionsCorresponding author

Nature Communications 5, Article number: 4164 doi:10.1038/ncomms5164

Received 06 April 2014 Accepted 19 May 2014 Published 24 June 2014

Source/Fonte: Arkive

Abstract

Convincing evidence that migrant monarch butterflies (Danaus plexippus) use a magnetic compass to aid their fall migration has been lacking from the spectacular navigational capabilities of this species. Here we use flight simulator studies to show that migrants indeed possess an inclination magnetic compass to help direct their flight equatorward in the fall. The use of this inclination compass is light-dependent utilizing ultraviolet-A/blue light between 380 and 420 nm. Notably, the significance of light <420 also="" an="" and="" antennae="" appear="" appropriate="" are="" as="" augment="" because="" compass="" considered="" contain="" cues="" daylight="" directional="" directionality="" font="" for="" function="" important="" in="" inclination="" light-sensitive="" magnetosensors.="" may="" mechanism="" migration.="" migratory="" monarch="" monarchs="" nm="" not="" orientation="" previous="" serve="" studies.="" sun="" the="" they="" throughout="" time-compensated="" to="" unavailable="" was="" when="">

Subject terms: Biological sciences Zoology

FREE PDF GRATIS: Nature Communications

Reavaliando o caráter biogênico do mais antigo traço de fóssil da Terra com implicações para bioassinaturas na busca de vida primitiva

Reassessing the biogenicity of Earth’s oldest trace fossil with implications for biosignatures in the search for early life

Eugene G. Grosch1 and Nicola McLoughlin

Author Affiliations

Department of Earth Science and Centre for Geobiology, University of Bergen, N-5007 Bergen, Norway

Edited* by Norman H. Sleep, Stanford University, Stanford, CA, and approved April 28, 2014 (received for review February 10, 2014)

Significance

It has been argued that Archean subseafloor pillow lava sequences provide an environment in which to seek evidence for the earliest traces of life. Candidate titanite biosignatures of microbial activity have been reported in ∼3.45-Ga metavolcanic glass from the Barberton greenstone belt of South Africa. In this paper we present new in situ U–Pb age data, metamorphic constraints, and morphological observations on these titanite microtextures. Our data challenges a biological origin for these oldest purported trace fossils, with implications for the ecological niches where life may have first emerged. We therefore suggest alternative biosignatures and approaches should be considered in the search for subsurface life on early Earth and in extraterrestrial mafic–ultramafic rocks, for example, in martian basalts.

Abstract

Microtextures in metavolcanic pillow lavas from the Barberton greenstone belt of South Africa have been argued to represent Earth’s oldest trace fossil, preserving evidence for microbial life in the Paleoarchean subseafloor. In this study we present new in situ U–Pb age, metamorphic, and morphological data on these titanite microtextures from fresh drill cores intercepting the type locality. A filamentous microtexture representing a candidate biosignature yields a U–Pb titanite age of 2.819 ± 0.2 Ga. In the same drill core hornfelsic-textured titanite discovered adjacent to a local mafic sill records an indistinguishable U–Pb age of 2.913 ± 0.31 Ga, overlapping with the estimated age of intrusion. Quantitative microscale compositional mapping, combined with chlorite thermodynamic modeling, reveals that the titanite filaments are best developed in relatively low-temperature microdomains of the chlorite matrix. We find that the microtextures exhibit a morphological continuum that bears no similarity to candidate biotextures found in the modern oceanic crust. These new findings indicate that the titanite formed during late Archean ca. 2.9 Ga thermal contact metamorphism and not in an early ca. 3.45 Ga subseafloor environment. We therefore question the syngenicity and biogenicity of these purported trace fossils. It is argued herein that the titanite microtextures are more likely abiotic porphyroblasts of thermal contact metamorphic origin that record late-stage retrograde cooling in the pillow lava country rock. A full characterization of low-temperature metamorphic events and alternative biosignatures in greenstone belt pillow lavas is thus required before candidate traces of life can be confirmed in Archean subseafloor environments.

Archean habitats astrobiology Archean Earth ichnofossil bioalteration

Footnotes

1To whom correspondence should be addressed. E-mail: geogene@gmail.com.

Author contributions: E.G.G. designed research; E.G.G. and N.M. performed research; E.G.G. and N.M. contributed new reagents/analytic tools; E.G.G. and N.M. analyzed data; and E.G.G. wrote the paper.

The authors declare no conflict of interest.

*This Direct Submission article had a prearranged editor.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1402565111/-/DCSupplemental.

Freely available online through the PNAS open access option.

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Definindo os elementos funcionais do DNA no genoma humano

Defining functional DNA elements in the human genome

Manolis Kellisa,b,1,2, Barbara Woldc,2, Michael P. Snyderd,2, Bradley E. Bernsteinb,e,f,2, Anshul Kundajea,b,3, Georgi K. Marinovc,3, Lucas D. Warda,b,3, Ewan Birneyg, Gregory E. Crawfordh, Job Dekkeri, Ian Dunhamg, Laura L. Elnitskij, Peggy J. Farnhamk, Elise A. Feingoldj, Mark Gersteinl, Morgan C. Giddingsm, David M. Gilbertn, Thomas R. Gingeraso, Eric D. Greenj, Roderic Guigop, Tim Hubbardq, Jim Kentr, Jason D. Liebs, Richard M. Myerst, Michael J. Pazinj, Bing Renu, John A. Stamatoyannopoulosv, Zhiping Wengi, Kevin P. Whitew, and Ross C. Hardisonx,1,2

Author Affiliations

Edited by Robert Haselkorn, University of Chicago, Chicago, IL, and approved January 29, 2014 (received for review October 16, 2013)

Abstract Authors & Info SIMetrics PDFPDF + SI

Abstract

With the completion of the human genome sequence, attention turned to identifying and annotating its functional DNA elements. As a complement to genetic and comparative genomics approaches, the Encyclopedia of DNA Elements Project was launched to contribute maps of RNA transcripts, transcriptional regulator binding sites, and chromatin states in many cell types. The resulting genome-wide data reveal sites of biochemical activity with high positional resolution and cell type specificity that facilitate studies of gene regulation and interpretation of noncoding variants associated with human disease. However, the biochemically active regions cover a much larger fraction of the genome than do evolutionarily conserved regions, raising the question of whether nonconserved but biochemically active regions are truly functional. Here, we review the strengths and limitations of biochemical, evolutionary, and genetic approaches for defining functional DNA segments, potential sources for the observed differences in estimated genomic coverage, and the biological implications of these discrepancies. We also analyze the relationship between signal intensity, genomic coverage, and evolutionary conservation. Our results reinforce the principle that each approach provides complementary information and that we need to use combinations of all three to elucidate genome function in human biology and disease.

Footnotes

1To whom correspondence may be addressed. E-mail: manoli@mit.edu or rch8@psu.edu.

2M.K., B.W., M.P.S., B.E.B., and R.C.H. contributed equally to this work.

3A.K., G.K.M., and L.D.W. contributed equally to this work.

Author contributions: M.K., B.W., M.P.S., B.E.B., and R.C.H. designed research; M.K., B.W., M.P.S., B.E.B., A.K., G.K.M., L.D.W., and R.C.H. performed research; A.K., G.K.M., and L.D.W. contributed computational analysis and tools; M.K., B.W., M.P.S., B.E.B., E.B., G.E.C., J.D., I.D., L.L.E., P.J.F., E.A.F., M.G., M.C.G., D.M.G., T.R.G., E.D.G., R.G., T.H., J.K., J.D.L., R.M.M., M.J.P., B.R., J.A.S., Z.W., K.P.W., and R.C.H. contributed to manuscript discussions and ideas; and M.K., B.W., M.P.S., B.E.B., and R.C.H. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

Data deposition: In addition to data already released via the ENCODE Data Coordinating Center, the erythroblast DNase-seq data reported in this paper have been deposited in the Gene Expression Omnibus (GEO) database, www.ncbi.nlm.nih.gov/geo (accession nos. GSE55579, GSM1339559, and GSM1339560).

Authored by members of the ENCODE Consortium.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1318948111/-/DCSupplemental.

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A consciência como um estado da matéria? Max Tegmark diz que sim.

Consciousness as a State of Matter

Max Tegmark (MIT)

(Submitted on 6 Jan 2014 (v1), last revised 27 Feb 2014 (this version, v2))

We examine the hypothesis that consciousness can be understood as a state of matter, "perceptronium", with distinctive information processing abilities. We explore five basic principles that may distinguish conscious matter from other physical systems such as solids, liquids and gases: the information, integration, independence, dynamics and utility principles. If such principles can identify conscious entities, then they can help solve the quantum factorization problem: why do conscious observers like us perceive the particular Hilbert space factorization corresponding to classical space (rather than Fourier space, say), and more generally, why do we perceive the world around us as a dynamic hierarchy of objects that are strongly integrated and relatively independent? Tensor factorization of matrices is found to play a central role, and our technical results include a theorem about Hamiltonian separability (defined using Hilbert-Schmidt superoperators) being maximized in the energy eigenbasis. Our approach generalizes Giulio Tononi's integrated information framework for neural-network-based consciousness to arbitrary quantum systems, and we find interesting links to error-correcting codes, condensed matter criticality, and the Quantum Darwinism program, as well as an interesting connection between the emergence of consciousness and the emergence of time.

Comments: Proof of H-diagonality theorem generalized to arbitrary n. References added to rho-diagonality theorem proof, typos corrected. 34 pages, 15 figs

Subjects: Quantum Physics (quant-ph); Disordered Systems and Neural Networks (cond-mat.dis-nn); High Energy Physics - Theory (hep-th)

Cite as: arXiv:1401.1219 [quant-ph]

(or arXiv:1401.1219v2 [quant-ph] for this version)

Submission history

From: Max Tegmark [view email] 

[v1] Mon, 6 Jan 2014 21:00:11 GMT (5812kb,D)

[v2] Thu, 27 Feb 2014 18:26:57 GMT (5690kb,D)

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Pesquisadores descobrem gene crucial para o desenvolvimento do cerebelo e amadurecimento neural

Snf2h-mediated chromatin organization and histone H1 dynamics govern cerebellar morphogenesis and neural maturation

Matías Alvarez-Saavedra, Yves De Repentigny, Pamela S. Lagali, Edupuganti V. S. Raghu Ram, Keqin Yan, Emile Hashem, Danton Ivanochko, Michael S. Huh, Doo Yang, Alan J. Mears, Matthew A. M. Todd, Chelsea P. Corcoran, Erin A. Bassett, Nicholas J. A. Tokarew, Juraj Kokavec, Romit Majumder, Ilya Ioshikhes, Valerie A. Wallace, Rashmi Kothary, Eran Meshorer et al.

AffiliationsContributionsCorresponding author

Nature Communications 5, Article number: 4181 doi:10.1038/ncomms5181

Received 12 February 2014 Accepted 15 May 2014 Published 20 June 2014

Source/Fonte

Abstract

Chromatin compaction mediates progenitor to post-mitotic cell transitions and modulates gene expression programs, yet the mechanisms are poorly defined. Snf2h and Snf2l are ATP-dependent chromatin remodelling proteins that assemble, reposition and space nucleosomes, and are robustly expressed in the brain. Here we show that mice conditionally inactivated for Snf2h in neural progenitors have reduced levels of histone H1 and H2A variants that compromise chromatin fluidity and transcriptional programs within the developing cerebellum. Disorganized chromatin limits Purkinje and granule neuron progenitor expansion, resulting in abnormal post-natal foliation, while deregulated transcriptional programs contribute to altered neural maturation, motor dysfunction and death. However, mice survive to young adulthood, in part from Snf2l compensation that restores Engrailed-1 expression. Similarly, Purkinje-specific Snf2h ablation affects chromatin ultrastructure and dendritic arborization, but alters cognitive skills rather than motor control. Our studies reveal that Snf2h controls chromatin organization and histone H1 dynamics for the establishment of gene expression programs underlying cerebellar morphogenesis and neural maturation.

Subject terms: Biological sciences Developmental biology Molecular biology Neuroscience

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Grandes disparidades entre as datas de divergência molecular e as idades dos fósseis de aves

Flying rocks and flying clocks: disparity in fossil and molecular dates for birds

Daniel T. Ksepka1,†⇑, Jessica L. Ware2,3 and Kristin S. Lamm4

- Author Affiliations

1National Evolutionary Synthesis Center, Durham, NC 27705, USA

2Department of Biology, Rutgers University, Newark, NJ 07102, USA

3American Museum of Natural History, Division of Invertebrate Zoology, 79th and Central Park West, New York, NY 10024, USA

4Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA

- Author Notes

↵† Present address: Bruce Museum, Greenwich, CT 06830, USA.

e-mail: ksepka@nescent.org

Abstract

Major disparities are recognized between molecular divergence dates and fossil ages for critical nodes in the Tree of Life, but broad patterns and underlying drivers remain elusive. We harvested 458 molecular age estimates for the stem and crown divergences of 67 avian clades to explore empirical patterns between these alternate sources of temporal information. These divergence estimates were, on average, over twice the age of the oldest fossil in these clades. Mitochondrial studies yielded older ages than nuclear studies for the vast majority of clades. Unexpectedly, disparity between molecular estimates and the fossil record was higher for divergences within major clades (crown divergences) than divergences between major clades (stem divergences). Comparisons of dates from studies classed by analytical methods revealed few significant differences. Because true divergence ages can never be known with certainty, our study does not answer the question of whether fossil gaps or molecular dating error account for a greater proportion of observed disparity. However, empirical patterns observed here suggest systemic overestimates for shallow nodes in existing molecular divergence dates for birds. We discuss underlying biases that may drive these patterns.

divergence dating palaeontology K–Pg extinction

Received March 20, 2014.

Accepted May 27, 2014.

© 2014 The Author(s) Published by the Royal Society. All rights reserved.

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Proceedings of the Royal Society B

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Duas hipóteses de como os órgãos coordenam seu desenvolvimento com o resto do corpo

Coordination of Wing and Whole-Body Development at Developmental Milestones Ensures Robustness against Environmental and Physiological Perturbations

Marisa M. Oliveira, Alexander W. Shingleton, Christen K. Mirth mail

Published: June 19, 2014DOI: 10.1371/journal.pgen.1004408

Abstract

Development produces correctly patterned tissues under a wide range of conditions that alter the rate of development in the whole body. We propose two hypotheses through which tissue patterning could be coordinated with whole-body development to generate this robustness. Our first hypothesis states that tissue patterning is tightly coordinated with whole-body development over time. The second hypothesis is that tissue patterning aligns at developmental milestones. To distinguish between our two hypotheses, we developed a staging scheme for the wing imaginal discs of Drosophila larvae using the expression of canonical patterning genes, linking our scheme to three whole-body developmental events: moulting, larval wandering and pupariation. We used our scheme to explore how the progression of pattern changes when developmental time is altered either by changing temperature or by altering the timing of hormone synthesis that drives developmental progression. We found the expression pattern in the wing disc always aligned at moulting and pupariation, indicating that these key developmental events represent milestones. Between these milestones, the progression of pattern showed greater variability in response to changes in temperature and alterations in physiology. Furthermore, our data showed that discs from wandering larvae showed greater variability in patterning stage. Thus for wing disc patterning, wandering does not appear to be a developmental milestone. Our findings reveal that tissue patterning remains robust against environmental and physiological perturbations by aligning at developmental milestones. Furthermore, our work provides an important glimpse into how the development of individual tissues is coordinated with the body as a whole.

Author Summary

Between distantly related species, development converges at common morphological and genetic stages, called developmental milestones, to ensure the establishment of a basic body plan. Beyond these milestones greater variability in developmental processes builds species-specific form. We reasoned that developmental milestones might also act within a species to achieve robustness against environmental or physiological perturbation. To address this, we first developed a staging scheme for the progression of pattern in the wing disc across developmental time. We then explored how perturbing environmental or physiological stimuli known to alter the rate of development affected the progression of pattern in the wing disc. We found two developmental milestones, the moult to the third instar and pupariation, where wing disc patterning aligned with the development of the whole body. This suggests that robustness against environmental and physiological conditions is achieved by coordinating tissue with whole-body development at developmental milestones.

Citation: Oliveira MM, Shingleton AW, Mirth CK (2014) Coordination of Wing and Whole-Body Development at Developmental Milestones Ensures Robustness against Environmental and Physiological Perturbations. 

PLoS Genet 10(6): e1004408. doi:10.1371/journal.pgen.1004408

Editor: Marc Robinson-Rechavi, University of Lausanne, Switzerland

Received: January 7, 2014; Accepted: April 14, 2014; Published: June 19, 2014

Copyright: © 2014 Oliveira et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: MMO is supported by a doctoral fellowship from the Fundação para a Ciência e a Tecnologia (SFRH/BD/51181/2010) and by Fundação Calouste Gulbenkian. This work was funded by the Fundação Calouste Gulbenkian to CKM and by the National Science Foundation (IOS-0845847 and IOS-0919855) to AWS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

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Pesquisa revela que o universo 'irregular' não explica a aceleração cósmica

Stringent Restriction from the Growth of Large-Scale Structure on Apparent Acceleration in Inhomogeneous Cosmological Models

Phys. Rev. Lett. 111, 251302 – Published 19 December 2013

Mustapha Ishak, Austin Peel, and M. A. Troxel

ABSTRACT

Probes of cosmic expansion constitute the main basis for arguments to support or refute a possible apparent acceleration due to different expansion rates in the Universe as described by inhomogeneous cosmological models. We present in this Letter a separate argument based on results from an analysis of the growth rate of large-scale structure in the Universe as modeled by the inhomogeneous cosmological models of Szekeres. We use the models with no assumptions of spherical or axial symmetries. We find that while the Szekeres models can fit very well the observed expansion history without a Λ, they fail to produce the observed late-time suppression in the growth unless Λ is added to the dynamics. A simultaneous fit to the supernova and growth factor data shows that the cold dark matter model with a cosmological constant (ΛCDM) provides consistency with the data at a confidence level of 99.65%, while the Szekeres model without Λ achieves only a 60.46% level. When the data sets are considered separately, the Szekeres with no Λ fits the supernova data as well as the ΛCDM does, but provides a very poor fit to the growth data with only 31.31% consistency level compared to 99.99% for the ΛCDM. This absence of late-time growth suppression in inhomogeneous models without a is consolidated by a physical explanation.

DOI: http://dx.doi.org/10.1103/PhysRevLett.111.251302

• Published 19 December 2013
• Received 1 July 2013

© 2013 American Physical Society

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Physical Review of Letters

Força da gravidade universal de Newton ainda uma questão aberta

Precision measurement of the Newtonian gravitational constant using cold atoms

G. Rosi, F. Sorrentino, L. Cacciapuoti, M. Prevedelli & G. M. Tino

AffiliationsContributionsCorresponding author

Nature (2014) doi:10.1038/nature13433

Received 10 January 2014 Accepted 22 April 2014 Published online 18 June 2014

Source/Fonte: Ars Technica

About 300 experiments have tried to determine the value of the Newtonian gravitational constant, G, so far, but large discrepancies in the results have made it impossible to know its value precisely1. The weakness of the gravitational interaction and the impossibility of shielding the effects of gravity make it very difficult to measure G while keeping systematic effects under control. Most previous experiments performed were based on the torsion pendulum or torsion balance scheme as in the experiment by Cavendish2 in 1798, and in all cases macroscopic masses were used. Here we report the precise determination of G using laser-cooled atoms and quantum interferometry. We obtain the value G = 6.67191(99) × 10−11 m3 kg−1 s−2 with a relative uncertainty of 150 parts per million (the combined standard uncertainty is given in parentheses). Our value differs by 1.5 combined standard deviations from the current recommended value of the Committee on Data for Science and Technology3. A conceptually different experiment such as ours helps to identify the systematic errors that have proved elusive in previous experiments, thus improving the confidence in the value of G. There is no definitive relationship between G and the other fundamental constants, and there is no theoretical prediction for its value, against which to test experimental results. Improving the precision with which we know G has not only a pure metrological interest, but is also important because of the key role that G has in theories of gravitation, cosmology, particle physics and astrophysics and in geophysical models.

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Source/Fonte: Nature

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A Teoria do Design Inteligente e outros problemas ideológicos, de Mary Midgley

Impact Special Issue: 

Intelligent Design Theory and other ideological problems

Mary Midgley

June 2007

Volume 2007, Issue 15

Pages i–48

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Uma rede quântica de relógios atômicos precisos: os evolucionistas precisam acertar o relógio molecular!

A quantum network of clocks

Peter Kómár, Eric M. Kessler, Michael Bishof, Liang Jiang, Anders S. Sørensen, Jun Ye, Mikhail D. Lukin

(Submitted on 22 Oct 2013)

The development of precise atomic clocks has led to many scientific and technological advances that play an increasingly important role in modern society. Shared timing information constitutes a key resource for positioning and navigation with a direct correspondence between timing accuracy and precision in applications such as the Global Positioning System (GPS). By combining precision metrology and quantum networks, we propose here a quantum, cooperative protocol for the operation of a network consisting of geographically remote optical atomic clocks. Using non-local entangled states, we demonstrate an optimal utilization of the global network resources, and show that such a network can be operated near the fundamental limit set by quantum theory yielding an ultra-precise clock signal. Furthermore, the internal structure of the network, combined with basic techniques from quantum communication, guarantees security both from internal and external threats. Realization of such a global quantum network of clocks may allow construction of a real-time single international time scale (world clock) with unprecedented stability and accuracy.

Comments: 13 pages, 5 figures

Subjects: Quantum Physics (quant-ph)

Cite as: arXiv:1310.6045 [quant-ph]

(or arXiv:1310.6045v1 [quant-ph] for this version)

Submission history

From: Eric M. Kessler [view email] 

[v1] Tue, 22 Oct 2013 20:00:20 GMT (777kb,D)

FREE PDF GRATIS: ArXiv

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NOTA DESTE BLOGGER:

Enquantos os físicos procuram exatidão com a aplicação de suas teorias e hipóteses, os evolucionistas têm somente um relógio molecular capenga que dá horas diferentes ao longo da história evolucionárias dos seres vivos!

Será que vai dar para acertar o relógio molecular por esses relógios atômicos???

Estruturas de galáxias satélites co-orbitantes ainda estão em conflito com a distribuição de galáxias anãs primordiais: mudança de paradigma?

Co-orbiting satellite galaxy structures are still in conflict with the distribution of primordial dwarf galaxies

Marcel S. Pawlowski, Benoit Famaey, Helmut Jerjen, David Merritt, Pavel Kroupa, Jörg Dabringhausen, Fabian Lüghausen, Duncan A. Forbes, Gerhard Hensler, François Hammer, Mathieu Puech, Sylvain Fouquet, Hector Flores, Yanbin Yang

(Submitted on 6 Jun 2014)

Source/Fonte: Space

Both major galaxies in the Local Group host planar distributions of co-orbiting satellite galaxies, the Vast Polar Structure (VPOS) of the Milky Way and the Great Plane of Andromeda (GPoA). The ΛCDM cosmological model did not predict these features. However, according to three recent studies the properties of the GPoA and the flattening of the VPOS are common features among sub-halo based ΛCDM satellite systems, and the GPoA can be naturally explained by satellites being acquired along cold gas streams. We point out some methodological issues in these studies: either the selection of model satellites is different from that of the observed ones, or an incomplete set of observational constraints has been considered, or the observed satellite distribution is inconsistent with basic assumptions. Once these issues have been addressed, the conclusions are different: features like the VPOS and GPoA are very rare (each with probability ≲10−3, and combined probability <10 a="" accretion="" along="" and="" are="" cold="" combined="" dwarf="" explanation="" font="" formation.="" from="" galaxy="" gpoa.="" if="" in="" is="" modelling="" natural="" no="" of="" origin="" paradigm="" planar="" remains="" satellites="" selected="" semi-analytic="" simulation="" standard="" streams="" structures="" the="" unexplained="" with="">

Comments: 19 pages, 9 figures, 6 tables, accepted for publication in MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Cite as: arXiv:1406.1799 [astro-ph.GA]

(or arXiv:1406.1799v1 [astro-ph.GA] for this version)

Submission history

From: Marcel Pawlowski [view email] 

[v1] Fri, 6 Jun 2014 20:00:03 GMT (815kb)

FREE PDF GRATIS: ArXiv

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NOTA DESTE BLOGGER:

Quando físicos e astrofísicos se deparam com anomalias que o paradigma aceito não explica, eles falam em revisar o paradigma. Já os biólogos, especialmente quando a questão é Darwin, eles fazem de conta que são cegos, surdos e mudos sobre a questão. Uma teoria científica falida desde 1859 e que posa de ortodoxia científica nos livros didáticos aprovados e indicados pelo MEC/SEMTEC/PNLEM, fica devendo explicações para as montanhas de evidências contra a teoria da evolução encontradas no contexto de justificação teórica.

Saiba mais de onde viemos, para onde vamos do ponto de vista científico

JC e-mail 4972, de 13 de junho de 2014

25. Tome Ciência - De onde viemos, para onde vamos

Especialistas debatem, neste programa, como teria surgido a vida humana em nosso planeta, e o próprio planeta, do ponto de vista científico

Mais de 150 anos depois da teoria da evolução, de Charles Darwin, o ser humano ainda se interroga sobre suas origens. Basta lembrar os criacionistas, que defendem a existência de uma inteligência superior por trás de todos os eventos de criação da vida. Desde 2008, cientistas do mundo inteiro se juntaram para colocar em funcionamento um túnel subterrâneo de 27 quilômetros de circunferência, só para poder examinar as condições do Big Bang - para muitos a origem do universo. O que também é contestado. Afinal, do ponto de vista científico, como teria surgido a vida humana em nosso planeta? E o próprio planeta? E como anda a nossa evolução biológica? Superada pelas intervenções da medicina? Mais dependentes da cultura?

Participantes:

Martin Makler, pesquisador do Centro Brasileiro de Pesquisas Físicas, o CBPF, e pós-doutor em física na área de cosmologia.

Ricardo Campos-da-Paz, biólogo e zoólogo, professor de evolução na Universidade Federal do Rio de Janeiro, a Unirio, com pós-doutorado no assunto, pois é um estudioso das teorias da evolução.

Cláudia Augusta de Morais Russo, professora do Departamento de Genética da Universidade Federal do Rio de Janeiro, a UFRJ, com pós-doutorado em genética animal e estudos dedicados aos processos evolutivos.

Apresentado pelo jornalista André Motta Lima, o programa conta com a participação de um Conselho Científico integrado pelas entidades vinculadas à Sociedade Brasileira para o Progresso da Ciência - SBPC, permitindo que cientistas de várias especialidades debatam temas da atualidade. Os debates são exibidos em diversas emissoras com variadas alternativas de horários. A programação pode ser conferida pelo site do programa: www.tomeciencia.com.br.

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PERGUNTA DESTE BLOGGER:

Esses especialistas irão considerar o atual status dessas teorias científicas da origem e evolução do universo e da vida no contexto de justificação teórica? Vão considerar seus pontos fracos e fortes? Especialmente os polêmicos e controversos? Ou vão dizer que já está tudo dominado pelos atuais paradigmas? Se assim for, o programa está em descompasso com a verdade das pesquisas e artigos de publicações científicas que mostram a necessidade mais do que premente de mudanças paradigmáticas.

Reconstrução histórica: ganhando acesso epistêmico do passado bem distante

Historical Reconstruction: Gaining Epistemic Access to the Deep Past 

Patrick Forber, Department of Philosophy, Tufts University, Miner Hall, 14 Upper Campus Road, Medford, MA 02155

Eric Griffith, Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115

e-mail: patrick.forber@tufts.edu

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SUBJECT TERMS

Consilience, Epistemology, Evidence, Evolutionary biology, Geology, Mass extinction

Article Type: Article

Volume 3, August 2011

DOI: http://dx.doi.org/10.3998/ptb.6959004.0003.003

Creative Commons License Permissions

Received 22 June 2010; Revised 23 November 2010; Accepted 5 May 2011

Abstract

We discuss the scientific task of historical reconstruction and the problem of epistemic access. We argue that strong epistemic support for historical claims consists in the consilience of multiple independent lines of evidence, and analyze the impact hypothesis for the End-Cretaceous mass extinction to illustrate the accrual of epistemic support. Although there are elements of the impact hypothesis that enjoy strong epistemic support, the general conditions for this are strict, and help to clarify the difficulties associated with reconstructing the deep past.

FREE PDF GRATIS: Philosophy & Theory in Biology

Mutação evolucionária aleatória: uma defesa da opinião consensual da Síntese Moderna

Evolutionary Chance Mutation: A Defense of the Modern Synthesis’ Consensus View

Francesca Merlin, Department of Philosophy, University of Montréal, 2910 Edouard Montpetit Blvd, Québec, H3T 1G7 Canada.

e-mail: francesca.merlin@gmail.com.

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SUBJECT TERMS

Biased chance, Chance, Darwin, Directed mutation, Lamarckism, Modern synthesis, Mutator mechanism, Random mutation

Article Type: Article

Volume 2, September 2010

DOI: http://dx.doi.org/10.3998/ptb.6959004.0002.003

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Received 24 May 2010; Revised 28 July 2010; Accepted 12 August 2010

Abstract

One central tenet of the Modern Evolutionary Synthesis (1930s-1950s), and the consensus view among biologists until now, is that all genetic mutations occur by “chance” or at “random” with respect to adaptation. However, the discovery of some molecular mechanisms enhancing mutation rate in response to environmental conditions has given rise to discussions among biologists, historians and philosophers of biology about the “chance” vs “directed” character of mutations (1980s-2000s). In fact, some argue that mutations due to a particular kind of mutator mechanisms challenge the Modern Synthesis because they are produced when and where needed by the organisms concerned. This paper provides a defense of the Modern Synthesis’ consensus view about the chance nature of all genetic mutations by reacting to Jablonka and Lamb’s analysis of genetic mutations (2005) and the explicit Lamarckian flavor of their arguments. I argue that biologists can continue to talk about chance mutations according to what I call and define as the notion of “evolutionary chance,” which I claim is the Modern Synthesis’ consensus view and a reformulation of Darwin’s most influential idea of “chance” variation. Advances in molecular genetics are therefore significant but not revolutionary with respect to the Modern Synthesis’ paradigm.

FREE PDF GRATIS: Philosophy & Theory in Biology

Variedades de coisas vivas: a vida na intersecção da linhagem e metabolismo

Varieties of Living Things: Life at the Intersection of Lineage and Metabolism

John Dupré, Egenis, University of Exeter, St Germans Road, Exeter, EX4 4PJ, UK

Maureen A. O’Malley, Egenis, University of Exeter, St Germans Road, Exeter, EX4 4PJ, UK

email: m.a.o’malley@exeter.ac.uk

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SUBJECT TERMS

Autonomy, Collaboration, Lineage formation, Living, Metabolic whole, Non-living

Article Type: Article

Volume 1, December 2009

DOI: http://dx.doi.org/10.3998/ptb.6959004.0001.003

Creative Commons License Permissions

Received 5 May 2009; Accepted 17 August 2009

Abstract

We address three fundamental questions: What does it mean for an entity to be living? What is the role of inter-organismic collaboration in evolution? What is a biological individual? Our central argument is that life arises when lineage-forming entities collaborate in metabolism. By conceiving of metabolism as a collaborative process performed by functional wholes, which are associations of a variety of lineage-forming entities, we avoid the standard tension between reproduction and metabolism in discussions of life – a tension particularly evident in discussions of whether viruses are alive. Our perspective assumes no sharp distinction between life and non-life, and does not equate life exclusively with cellular or organismal status. We reach this conclusion through an analysis of the capabilities of a spectrum of biological entities, in which we include the pivotal case of viruses as well as prions, plasmids, organelles, intracellular and extracellular symbionts, unicellular and multicellular life-forms. The usual criterion for classifying many of the entities of our continuum as non-living is autonomy. This emphasis on autonomy is problematic, however, because even paradigmatic biological individuals, such as large animals, are dependent on symbiotic associations with many other organisms. These composite individuals constitute the metabolic wholes on which selection acts. Finally, our account treats cooperation and competition not as polar opposites but as points on a continuum of collaboration. We suggest that competitive relations are a transitional state, with multi-lineage metabolic wholes eventually outcompeting selfish competitors, and that this process sometimes leads to the emergence of new types or levels of wholes. Our view of life as a continuum of variably structured collaborative systems leaves open the possibility that a variety of forms of organized matter – from chemical systems to ecosystems – might be usefully understood as living entities.

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FREE PDF GRATIS: Philosophy & Theory in Biology