Heat to electricity thermoacoustic-magnetohydrodynamic conversion

In this work, a new concept for the conversion of heat into electricity is presented. The conversion is based on the combined effects of a thermoacoustic prime mover coupled with a magnetohydrodynamic generator, using different working fluids in each process. The results of preliminary experiments are also presented.Comment: Short article, 5 figures, 5 page

Стратегії проповідницького дискурсу І. Галятовського: антропологічний аспект

How cells in developing organisms interpret the quantitative information contained in morphogen gradients is an open question. Here we address this question using a novel integrative approach that combines quantitative measurements of morphogen-induced gene expression at single-mRNA resolution with mathematical modelling of the induction process. We focus on the induction of Notch ligands by the LIN-3/EGF morphogen gradient during vulva induction in Caenorhabditis elegans. We show that LIN-3/EGF-induced Notch ligand expression is highly dynamic, exhibiting an abrupt transition from low to high expression. Similar transitions in Notch ligand expression are observed in two highly divergent wild C. elegans isolates. Mathematical modelling and experiments show that this transition is driven by a dynamic increase in the sensitivity of the induced cells to external LIN-3/EGF. Furthermore, this increase in sensitivity is independent of the presence of LIN-3/EGF. Our integrative approach might be useful to study induction by morphogen gradients in other systems

Experimental Observation of Differences in the Dynamic Response of Newtonian and Viscoelastic Fluids

In this paper we present an experimental study of the dynamic responses of a Newtonian fluid and a Maxwellian fluid under an oscillating pressure gradient. We use laser Doppler anemometry in order to determine the velocity of each fluid inside a cylindrical tube. In the case of the Newtonian fluid, the dissipative nature is observed and the response obeys the Zhou and Sheng universality (PRB 39, 12027 (1989)). In the dynamic response of the Maxwellian fluid an enhancement at the frequencies predicted by the corresponding theory (PRE 58, 6323 (1998)) is observed.Comment: 5 pages, 4 Figures, paper to be published in Phys. Rev.

Snooping on cells in worms and mini-organs

Throughout their lifetime, animals face a wide variety of biological challenges. Starting out as single cells, their _rst challenge is to undergo development and become fully grown and functional adults. Remarkably, this incredibly complex process occurs in a highly reproducible manner despite the huge variability in environmental, genetic and molecular uctuations they encounter during their journey through development. However, the challenges do not end here; once animals become adults, their tissues are constantly subject to damage, either by external sources such as disease, or due to intrinsic causes such as cellular aging. Thus, adult tissues are constantly renewing themselves, and must do so in a tightly controlled manner in order to maintain homeostasis. In this thesis, we explore how animals cope with a few of such challenges with the help of two model systems, C. elegans worms and stem cell-derived organoids.BN/Sander Tans La

Heat transfer by natural convection and radiation in three dimensional differentially heated tall cavities

Natural convection coupled with radiation is numerically studied in a tall rectangular parallelepiped cavity filled with air and constant differentially heated opposite vertical walls. This type of tall cavity is found in walls built with hollow blocks. Three dimensional steady state numerical simulations are performed. Numerical models for pure natural convection and natural convection coupled with radiation are validated with experimental results. In this work, the tall cavity studied has a 0.06 m width, 0.155 m depth and a 2.56 m height, giving a vertical aspect ratio of A=42.7 and a horizontal aspect ratio of A′=2.6. The cold wall temperature, Tc, is fixed. The hot wall temperature, Th, is varied, obtaining the Rayleigh numbers: RaW, 1.01×104, 1.07×105 and 7.20×105. The emissivity, ϵ, varies from 0.0 to 1.0. The results show that with a given Th, the convective Nusselt number, Nuc, depends on ϵ. For the emissivity value of hollow block materials (ϵ=0.8) the radiative heat transfer represents 83% for the lowest Th. For pure natural convection, a Nuc correlation as a function of RaW is obtained. A simplified calculation of the total heat transfer, Nut, is proposed

Structured and fractal smoke patterns in a simple cavity

While conducting a study with air in a simple closed rectangular cavity, we have discovered the formation of highly impressive, complex-structured, and symmetrical smoke density patterns. Using the box counting method the fractal characteristic of the patterns is demonstrated