Dynamics of a sliding‐rocking block considering impact with an adjacent wall

By using linear stability theory, we demonstrate theoretically that the critical Reynolds number for the loss of stability of planar Poiseuille flow can be significantly increased or decreased through the use of feedback control strategies which enhance or suppress disturbance dissipating mechanisms in the flow. The controller studied here consists of closely packed, wall mounted, shear stress sensors and thermoelectric actuators. The sensors detect flow instabilities and direct the actuators to alter the fluid’s viscosity by modulating the adjacent wall temperature in such a way as to suppress or enhance flow instabilities. Results are presented for water and air flows.

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Oscillations of a rocking block with an added pendulum

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1177/0959651815616715 ◽

2015 ◽

Vol 230 (2) ◽

pp. 104-114 ◽

Cited By ~ 1

Author(s):

Luca Collini ◽

Rinaldo Garziera ◽

Aleksander V Karapetyan ◽

Maria A Munitsyna ◽

Alessandro Tasora

Keyword(s):

Rocking Block

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Transplantations de gonades indifférenciées chez l'hermaphrodite simultané Eisenia foetida (Oligochète, Lumbricidae)

Development ◽

10.1242/dev.30.1.143 ◽

1973 ◽

Vol 30 (1) ◽

pp. 143-161

Author(s):

Par J. C. Relexans

Keyword(s):

Nervous System ◽

Sexual Differentiation ◽

The Body ◽

Simultaneous Hermaphrodite ◽

Eisenia Foetida ◽

Turn On ◽

Opposite Sex ◽

Adjacent Wall ◽

Physiological Gradients ◽

Different Parts

Transplantations of undifferentiated gonads in the simultaneous hermaphrodite Eisenia foetida (Oligochaeta, Lumbricidae) leading to evidence of local factors (inductors?) of sexual differentiation The hypothesis of a ♀ sex capable of autodifferentiation and of a ♂ sex depending on an androgen hormone has been verified in several gonochoric or hermaphrodite invertebrates. In order to test the validity of this hypothesis in the hermaphrodite Eisenia foetida we have investigated the influence of the gonads' environment on their differentiation by transplanting undifferentiated gonads, dorsally and ventrally, on different parts of the body. The gonads, taken with the adjacent wall of the body from new-born worms, are grafted on worms of the same age; some grafts do, others do not, retain their nervous system. The control transplantation in which a graft of a given presumptive sex is transplanted in a region of the same sex can lead to inversions. These inversions have a rare and short-lived character in the gonads coming from presumptive testes. They are more frequent and more or less durable in the gonads coming from presumptive ovaries. These results can only be explained by the existence, within the grafts of the two presumptive sexes, of a dominant relationship between one and the other sexual potentiality which can be momentarily inverted by trophic disturbances caused by the transplantation. The heterosexual transplantations, in which a graft of a given presumptive sex is transplanted in the region of the opposite sex, show that the frequency of the inversions is doubled in relation to the frequency obtained in the control transplantations. The inversions which occur in the presumptive testes can be lasting and even permanent. These results lead to the opinion that to the effects of transplantation is added an inductive action from the host, leading to masculinity in the ♂ region and femininity in the ♀ region. The transplantations outside of the sexual ventral regions lead to inversions of which the character and frequency recall those obtained in the control transplantations. They suggest that these regions are devoid of inductive sexualizing power. The very slight variations of frequency of the inversions observed along the antero-posterior and dorso-ventral axes can be explained by the existence of physiological gradients acting on the balance of the graft's own potentialities. The removal of the nervous system in the grafts shows that this system plays a part, probably trophic, in favour of the masculine potentialities of the graft. In conclusion, our experiments lead to the rejection of the hypothesis of the ♀ sex capable of autodifferentiation in Eisenia, in order to adopt that of a sexual balance between the ♂ and ♀ potentialities determining, according to their dominant relationship, the synthesis of ♂ or ♀ ‘inductors’ respectively in the ♂ and ♀ ventral regions. These inductors act in turn on the bipotential sexual cells.

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Direct evidence for fluid overpressure during hydrocarbon generation and expulsion from organic-rich shales

Geology ◽

10.1130/g46650.1 ◽

2020 ◽

Vol 48 (4) ◽

pp. 374-378

Author(s):

Miao Wang ◽

Yong Chen ◽

Wyatt M. Bain ◽

Guoqi Song ◽

Keyu Liu ◽

...

Keyword(s):

Direct Evidence ◽

Wall Rock ◽

Source Rocks ◽

Bohai Bay ◽

Hydrocarbon Generation ◽

Calcite Veins ◽

History Of ◽

Fluid Overpressures ◽

Adjacent Wall ◽

Record Variable

Abstract Fluid overpressures are widely expected during hydrocarbon generation and expulsion from source rocks, yet direct evidence for this phenomenon is lacking in the case of organic-rich shales. Here we show that formation of bed-parallel fibrous calcite veins in mature laminated organic-rich shales in the Eocene Dongying depression, Bohai Bay Basin, east China, occurred in direct response to fluid overpressure due to hydrocarbon generation. The evidence for overpressure is recorded by coexisting primary aqueous and petroleum inclusions in the calcite fibers. Our results show that all analyzed fluid-inclusion assemblages record variable degrees of overpressure during vein dilation, ranging from only modestly in excess of hydrostatic, to approaching and perhaps exceeding lithostatic. Thus, our results indicate that fluid pressures during dilation of horizontal veins are not necessarily equal to the opposing force of overburden throughout the history of opening. This suggests that at least some of the vein dilation is accommodated by concomitant narrowing of the adjacent wall-rock laminae, likely by scavenging (dissolution and reprecipitation) of CaCO3 from the adjacent wall rock.

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FmhA and FmhC of Staphylococcus aureus incorporate serine residues into peptidoglycan cross-bridges

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.014371 ◽

2020 ◽

Vol 295 (39) ◽

pp. 13664-13676 ◽

Cited By ~ 1

Author(s):

Stephanie Willing ◽

Emma Dyer ◽

Olaf Schneewind ◽

Dominique Missiakas

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Binding Proteins ◽

Penicillin Binding Proteins ◽

Daughter Cells ◽

Cross Bridge ◽

Resistant Strains ◽

The Cross ◽

Cross Bridges ◽

Adjacent Wall

Staphylococcal peptidoglycan is characterized by pentaglycine cross-bridges that are cross-linked between adjacent wall peptides by penicillin-binding proteins to confer robustness and flexibility. In Staphylococcus aureus, pentaglycine cross-bridges are synthesized by three proteins: FemX adds the first glycine, and the homodimers FemA and FemB sequentially add two Gly-Gly dipeptides. Occasionally, serine residues are also incorporated into the cross-bridges by enzymes that have heretofore not been identified. Here, we show that the FemA/FemB homologues FmhA and FmhC pair with FemA and FemB to incorporate Gly-Ser dipeptides into cross-bridges and to confer resistance to lysostaphin, a secreted bacteriocin that cleaves the pentaglycine cross-bridge. FmhA incorporates serine residues at positions 3 and 5 of the cross-bridge. In contrast, FmhC incorporates a single serine at position 5. Serine incorporation also lowers resistance toward oxacillin, an antibiotic that targets penicillin-binding proteins, in both methicillin-sensitive and methicillin-resistant strains of S. aureus. FmhC is encoded by a gene immediately adjacent to lytN, which specifies a hydrolase that cleaves the bond between the fifth glycine of cross-bridges and the alanine of the adjacent stem peptide. In this manner, LytN facilitates the separation of daughter cells. Cell wall damage induced upon lytN overexpression can be alleviated by overexpression of fmhC. Together, these observations suggest that FmhA and FmhC generate peptidoglycan cross-bridges with unique serine patterns that provide protection from endogenous murein hydrolases governing cell division and from bacteriocins produced by microbial competitors.

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Reconstruction of the tower in defensive walls in Świebodzice

E3S Web of Conferences ◽

10.1051/e3sconf/20184900070 ◽

2018 ◽

Vol 49 ◽

pp. 00070

Author(s):

Anna Małachowicz

Keyword(s):

Seventeenth Century ◽

Oil Painting ◽

Ground Floor ◽

The Public ◽

The City ◽

Adjacent Wall

Fortification of Świebodzice, as presented in the eighteenthcentury drawings of Friedrich Bernhard Wernher, comprised one ring of walls, three gates in the form of towers with a passage on the ground floor, a rectangular gatehouse matching the height of the adjacent wall, and at least 8 rectangular towers. The entire fortification was surrounded by a moat. These architectural forms are in accordance with the oldest view over the city presented in the seventeenth-century oil painting [1]. The walls were crowned with rectangular battlements. Elements known from iconography were confirmed during research and inventory works initiated in 2007. The project, which was an aim of revitalizing the part of defensive walls along Piłsudskiego street in Świebodzice, was not only to make this relic accessible to the public (there is an observation deck in the defensive tower), but also to repair deformations formed as a result of the first restoration and because of the didactic exposition of wooden elements in the wall crowning (these elements were popular in medieval fortifications).

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