Localised edge states nucleate turbulence in extended plane Couette cells

We study the turbulence transition of plane Couette flow in large domains where localised perturbations are observed to generate growing turbulent spots. Extending previous studies on the boundary between laminar and turbulent dynamics we determine invariant structures intermediate between laminar and turbulent flow. In wide but short domains we find states that are localised in spanwise direction, and in wide and long domains the states are also localised in downstream direction. These localised states act as critical nuclei for the transition to turbulence in spatially extended domains.Comment: 15 pages, 5 figure

Continuity and Change in Howard S. Becker's work: An Interview with Howard S. Becker

Howard S. Becker is one of the foremost sociologists of the second half of the twentieth century. Although he is perhaps best known for research on deviance and his book Outsiders, this constitutes only a very small fraction of his earliest work. This interview looks at some of the continuities and cores of his work over ?fifty years. Becker highlights how his work maintains the same core concerns, although new interests have been added over time. At the core is a concern with 'work' and 'doing things together.' Becker provides many concrete stories from the past and also raises issues about the nature of doing theory and research, how he writes and produces his studies, and the problems attached to the professionalization of sociology. His writing on art and culture can be seen as assuming a major position in his later work, but he does not identify with either postmodernism or cultural studies

Pathways to double ionization of atoms in strong fields

We discuss the final stages of double ionization of atoms in a strong linearly polarized laser field within a classical model. We propose that all trajectories leading to non-sequential double ionization pass close to a saddle in phase space which we identify and characterize. The saddle lies in a two degree of freedom subspace of symmetrically escaping electrons. The distribution of longitudinal momenta of ions as calculated within the subspace shows the double hump structure observed in experiments. Including a symmetric bending mode of the electrons allows us to reproduce the transverse ion momenta. We discuss also a path to sequential ionization and show that it does not lead to the observed momentum distributions.Comment: 10 pages, 10 figures; fig.6 and 7 exchanged in the final version accepted for publication in Phys. Rev.

Analysis of nucleosome repositioning by yeast ISWI and Chd1 chromatin remodeling complexes

ISWI proteins form the catalytic core of a subset of ATP-dependent chromatin remodelling activities in eukaryotes from yeast to man. Many of these complexes have been found to reposition nucleosomes, but with different directionalities. We find that the yeast Isw1a, Isw2 and Chd1 enzymes preferentially move nucleosomes towards more central locations on short DNA fragments whereas Isw1b does not. Importantly, the inherent positioning properties of the DNA play an important role in determining where nucleosomes are relocated to by all of these enzymes. However, a key difference is that the Isw1a, Isw2 and Chd1 enzymes are unable to move nucleosomes to positions closer than 15 bp from a DNA end whereas Isw1b can. We also find that there is a correlation between the inability of enzymes to move nucleosomes close to DNA ends and the preferential binding to nucleosomes bearing linker DNA. These observations suggest that the accessibility of linker DNA together with the positioning properties of the underlying DNA play important roles in determining the outcome of remodelling by these enzymes

Viabilidade de blastocistos de Mus musculus domesticus expostos à alta pressão gasosa e submetidos à criopreservação

A alta pressão gasosa (high gaseous pressure, HGP) tem sido descrita como um agente estressante capaz de induzir resposta ao estresse subletal, fornecendo proteção celular a estresses subsequentes, como a criopreservação, embora os mecanismos celulares envolvidos ainda não estejam elucidados. Este princípio foi investigado em blastocistos murinos expostos a diferentes tratamentos utilizando-se HGP, seguidos ou não de criopreservação. De um total de 427 fêmeas de Mus musculus domesticus superovuladas, 308 (72,1%) produziram 3070 blastocistos viáveis (média de 7,2 ± 11,5 blastocistos/fêmea superovulada e de 10,0 ± 12,5 blastocistos/fêmea responsiva ao tratamento superovulatório) que foram expostos a tratamentos de distintas pressões e tempos de exposição, em quatro grupos experimentais: (a) 20,7 MPa por 2 h (P20.T2); (b) 20,7 Mpa por 4 h (P20.T4); (c) 27,6 Mpa por 2 h (P27.T2); e (d) 34,5 Mpa por 2 h (P34.T2). Todos os grupos foram pareados com controles não expostos à HGP. No primeira parte do experimento, embriões foram expostos à HGP, conforme os grupos experimentais acima, e posteriormente submetidos ao cultivo in vitro por 72 h com o objetivo de verificar a influência dos protocolos de HGP sobre a taxa de eclosão. Não houve diferença nas taxas de eclosão e na morfologia entre os grupos experimentais e os controles. Já na segunda parte do experimento, os embriões foram expostos à HGP, conforme os grupos experimentais acima, e posteriormente criopreservados por curva de congelamento clássica (rápida). Após o descongelamento, os embriões foram cultivados in vitro por 72 h para a avaliação das taxas de eclosão entre os grupos. A taxa de eclosão do Grupo P34.T2 foi significativamente maior do que a dos controles criopreservados não expostos à HGP (70,2% vs. 58,6%, p < 0,05). Conclui-se que a HGP pode ser usada como agente estressor subletal sem perda da viabilidade embrionária, e que o uso da HGP de 34,5 MPa por 2 h prévio à criopreservação modificou positivamente a taxa de sobrevivência in vitro de blastocistos murinos criopreservados.High gaseous pressure (HGP) has been reported as a sublethal stressor able to induce "sublethal stress response”, providing cell protection to subsequent stress, such as cryopreservation, although the involved cellular mechanisms are little understood. This principle was investigated on murine blastocysts exposed to different HGP treatments with and without subsequent cryopreservation. A total of 308 (72.1%) out of 427 superovulated Mus musculus domesticus females produced 3,070 viable blastocysts (7.2 ± 11.5 blastocysts/superovulated mouse and 10.0 ± 12.5 blastocysts/female responsive to superovulation) that were exposed to distinct pressure intensities and exposure times, according to four experimental groups: (a) 20.7 MPa for 2 h (P20.T2); (b) 20.7 MPa for 4 h (P20.T4); (c) 27.6 MPa for 2 h (P27.T2); and (d) 34.5 MPa for 2 h (P34.T2). All groups were compared with non-exposed HGP controls. In the first part of the experiment, embryos were exposed to HGP treatments, according to the experimental groups as above, and subsequently in vitro-cultured for 72 h aiming to compare the effects of the HGP protocols on subsequent hatching rates. No differences in hatching rates and morphology were observed between experimental and control groups. In the second parto of the experiment, embryos were exposed to HGP treatments, according to the experimental groups as above, and subsequently cryopreserved by rapid (classic) freezing. After thawing, embryos were in vitro-cultured for 72 h to compare hatching rates between groups. Hatching rates in the P34.5.T2 group were significantly higher than for the cryopreserved control embryos with no HGP treatment (70.2% vs. 58.6%, p < 0.05). Therefore, we conclude that HGP can be used as a stressor without compromising subsequent in vitro embryo viability, and the use of HGP at 34.5 MPa for 2 h prior to cryopreservation improved the in vitro survival of cryopreserved murine blastocysts compared with control counterparts

Intervenção estatal na economia e o desvio de função do cade no controle de atos de concentração

O presente trabalho tem o objetivo principal de apresentar o caráter intervencionista da atividade estatal do controle de atos de concentração a partir de duas perspectivas distintas. A primeira identifica-se pelo histórico, evidenciado nos últimos anos, do incentivo estatal às concentrações econômicas com vistas a criação de grandes conglomerados, principalmente por meio do Banco Nacional de Desenvolvimento Econômico e Social ("BNDES"). A segunda advém do desvio de valores jurídicos como a livre iniciativa e o não intervencionismo consubstanciado no controle de atos de concentração realizado pelo Conselho Administrativo de Defesa Econômica ("CADE"), que acaba por exceder suas funções primárias. Para maior clareza, o presente trabalho encontra-se dividido em três partes: fundamentos históricos, bases jurídicas e a análise de julgamentos de atos de concentração ("ACs") em 2010 à luz da Lei nº 8.884/94. Ao fim, aborda brevemente as alterações do controle de ACs trazidas pela Lei nº 12.529, recentemente sancionada pela Presidência da República. A metodologia utilizada nas duas primeiras partes foi a bibliográfica não sistemática, enquanto na terceira parte foi utilizado o método de estudo de caso indutivo, a partir da análise de julgados do CADE no ano de 2010. Os resultados demonstram que há, de fato, um forte intervencionismo estatal no que se refere às questões trabalhadas. De um lado, o Estado fomentara criação de grandes grupos econômicos – os assim chamados "campeões nacionais". De outro, excede sua função de controlar o potencial abuso de poder econômico ao impor à iniciativa privada a elevada submissão de atos de concentração ao CADE. A esse respeito, a Lei que reestrutura o Sistema Brasileiro de Defesa da Concorrência ("SBDC") prevê poucas alterações no que se refere ao aspecto intervencionista do controle de atos de concentração.This work aims to present the interventionist nature of the state activity in the merger control from two different perspectives. The first is identified by the history of state policy of incentive to large economic groups, primarily through the Brazilian Development Bank ("BNDES"). The second comes from the misuse of legal values such as free enterprise and non-interventionism as reflected in the excessive merger control performed by the Brazilian Council for Economic Defense ("CADE"). For a better clarity, the work is divided in three sections: historical and legal foundations of the merger control, and the analysis of the decisions on merger control in the year of 2010 under the Competition Law No. 8.884/94. At the end, briefly discusses the changes in Merger Control provided by the Statute No. 12.529, recently sanctioned by the Presidency of the Republic. The methodology used in the first two parts was the non-systematic literature review, while in the third part was applied the inductive case study method in the CADE`s decisions in 2010. The results show that there is indeed a strong state intervention regarding the issues addressed by the research. On the one hand, the State stimulates the creation of large economic groups - the so-called "national champions". On the other, exceeds its control function to prevent the potential abuse of economic power, since it imposes to the private enterprise a high level of filling of Mergers. The Statute that restructures the Brazilian Competition Policy System ("BCPS") provides few changes regarding the interventionist aspect of the Brazilian Merger Control

Determinação do efeito da alta pressão gasosa sobre oócitos imaturos de Bos taurus taurus e embriões de Mus musculus domesticus na eficiência da produção in vitro de embriões

A alta pressão gasosa (HGP, do inglês high gaseous pressure) tem sido descrita como um agente estressante capaz de induzir respostas ao estresse subletal, fornecendo proteção celular e estímulos positivos a desafios subsequentes, como a criopreservação, produção in vitro de embriões (PIVE) , entre outras biotécnicas da reprodução, embora os mecanismos celulares, a modulação epigenética e as modificações no padrão de expressão gênica envolvidos ainda não estejam totalmente elucidados. Este princípio foi investigado em gametas bovinos e embriões murinos no presente trabalho. Foram realizados dois experimentos independentes. No primeiro, avaliou-se o efeito da exposição de oócitos bovinos no estádio de vesículas germinativa à HGP na eficiência e cinética de desenvolvimento da PIVE por fecundação in vitro (FIV). Os resultados revelaram que oócitos expostos a HGP em temperatura ambiente apresentaram taxa de maturação in vitro (MIV) e cinética de desenvolvimento até o estádio de blastocisto semelhantes ao controle mantido em condições ideais durante o tratamento do grupo experimental, diferentemente do observado no grupo com CCOs mantidos em temperatura ambiente durante a exposição à HGP. Em um segundo experimento, observou-se as alterações no padrão de expressão gênica de blastocistos murinos expostos previamente à alta pressão gasosa no estádio de embrião de 8-células, bem como se este desafio alterava a taxa de sobrevivência destes blastocistos após serem submetidos ao processo de criopreservação. A análise do padrão de transcrição revelou que um gene associado ao estresse oxidativo (Sod2) teve sua expressão aumentada, enquanto genes de proliferação e desenvolvimento (Igf2 e Igf2R) tiveram sua expressão reduzida, quando comparados com os embriões no estádio de 8-células, embora a relação Igf2/Igf2R não demonstrou ser afetada. O tratamento por HGP mostrou-se eficiente no aumento da taxa de sobrevivência de blastocistos após a criopreservação. Os experimentos permitiram concluir que a resposta ao estresse subletal estimulada pela HGP é eficiente na melhora da performance de gametas femininos e embriões submetidos a novas situações estressantes.High gaseous pressure (HGP) has been described as stressor, providing cell protection and positive stimuli to subsequent challenges like cryopreservation, embryo in vitro production (IVP), among other reproduction biotechnologies, although cells mechanisms, epigenetic modulation and transcriptional modifications are not totally elucidated. This principle was investigated in bovine gametes and murine embryos in this report at two independent studies. First, the effect of bovine oocyte exposure to HGP in germinal vesicle stage was evaluated to efficiency and development kinect of IVP by in vitro fertilization (IVF). Results showed that oocytes exposed to HGP at room temperature had in vitro maturation (IVM) rate and developmental kinect to reach the blastocyst stage similar to control group kept in ideal conditions during experimental group treatment, differently that what was observed in the group with COCs just kept at room temperature during HGP exposure. In the second experiment, modifications in transcriptional response were observed in murine blastocysts previously exposed to HGP when embryo 8-cells stage, as well if this challenge modified survival rate of this blastocysts after cryopreservation procedures. The analysis of the transcriptional pattern revealed that a gene associated to oxidative stress (Sod2) was upregulated, while genes of proliferation and development (Igf2 and Igf2R) were downregulated, when compared with 8-cells embryos, even though the ratio Igf2/Igf2R appeared not be affected. HGP treatment showed to be efficient to improve blastocyst survival rate to cryopreservation. The experiments enable inferring that subletal response stimulated by HGP was efficient to enhance performance of female gametes and embryos exposed to new stressor situations