The Zoo of Non-Fourier Heat Conduction Models

The Fourier heat conduction model is valid for most macroscopic problems. However, it fails when the wave nature of the heat propagation or time lags become dominant and the memory or/and spatial non-local effects significant -- in ultrafast heating (pulsed laser heating and melting), rapid solidification of liquid metals, processes in glassy polymers near the glass transition temperature, in heat transfer at nanoscale, in heat transfer in a solid state laser medium at the high pump density or under the ultra-short pulse duration, in granular and porous materials including polysilicon, at extremely high values of the heat flux, in heat transfer in biological tissues. In common materials the relaxation time ranges from $10^{-8}$ to $10^{-14}$ sec, however, it could be as high as 1 sec in the degenerate cores of aged stars and its reported values in granular and biological objects varies up to 30 sec. The paper considers numerous non-Fourier heat conduction models that incorporate time non-locality for materials with memory (hereditary materials, including fractional hereditary materials) or/and spatial non-locality, i.e. materials with non-homogeneous inner structure

A study of cis-regulatory elements in Xenopus and planarians

Multicellular organisms have the ability to produce and maintain several cell types despite the DNA molecule being the same in all cells. For that, a complex network of cis-regulatory elements (CRE) and transcription factors is involved in controlling cellular fate. Among the different approaches that allow the identification of CREs, the novel ATAC-sequencing is becoming an increasingly used tool due to its easy-to-perform protocol. In this study, this technique has been optimized to beused in two species (Xenopus laevis and Schmidtea mediterranea) to elucidate (1) the epigenetic mechanism behind Xenopus neural crest (NC) specification and differentiation, and (2) the establishment of anteroposterior identity during planarian regeneration.ATAC-sequencing has been carried out on Xenopus animal caps induced to give rise to NC or neural tissue. Comparison of this data along with non-injected ectodermal animal caps has led to the characterization of the epigenome involved in Xenopus neural crest formation. Results show that 4,528 NC open regions or potential enhancers are present during specification whereas 852 NC potential enhancers are specific for differentiation. In these NC open regions, the transcription factors Zic, Meis and Sox10 play an important role. Five enhancers driving expression of key neural crest genes (cmyc, foxd3, id3, snai2 and sox10) have been identified. ATAC-sequencing has also been successfully validated on dissected blastemas from 48h regenerating planarians. The analysis has revealed nervous system-related transcription factor motifs such as Prep or NeuroD-1 present in anterior specific open regions whereas posterior polarity-related transcription factor binding sites such as Islet or HoxD3 are present in posterior open regions. Key words: ATAC-sequencing, enhancer, transcription factor, Xenopus neural crest, planarian, anteroposterior polarity

日本医科大学研究業績年報 第45巻 平成10(1998年度)

日本医科大

日本医科大学研究業績年報 第54巻 平成19(2007年度)

日本医科大