The diffusion coefficient of fluorescein in detached cilia of Xenopus laevis olfactory receptor neurons was measured using spatially-resolved FRAP, where the dye along half of the ciliary length was photobleached and its spatiotemporal fluorescence redistribution recorded. Fitting a one-dimensional numerical simulation of diffusion and photobleaching for 35 cilia resulted in a mean value of the...

The diffusive arrival of transcription factors at the promoter sites on the DNA sets a lower bound on how accurately a cell can regulate its protein levels. Using results from the literature on diffusion-influenced reactions, we derive an analytical expression for the lower bound on the precision of transcriptional regulation. In our theory, transcription factors can perform multiple rounds of ...

Combining dispersion measures, distances and emission measures for 157 pulsars lying above | b |> 5 and between 60 < l < 360 we find the mean volume filling factor (f̄v) of the diffused ionized gas in the Milky Way. This filling factor is inversely related to the mean electron density (n̄c) in the clouds, f̄v = (0.0184± 0.0014)n̄c , implying a nearly constant average electron density distribution w...

There is now a certain consensus that transcription factors (TFs) reach their target sites, where they regulate gene transcription, via a mechanism dubbed facilitated diffusion (FD). In FD, the TF cycles between events of 3D diffusion in solution (jumps), 1D diffusion along DNA (sliding), and small jumps (hopping), achieving association rates higher than for 3D diffusion alone. We investigate t...

It has long been asserted that proteins such as transcription factors may locate their target in DNA sequences at rates that surpass by several orders of magnitude the three-dimensional diffusion limit thanks to facilitated diffusion, that is, the combination of one-dimensional (sliding along the DNA) and three-dimensional diffusion. This claim has been supported throughout the years by several...

materials and methods the segmentation process is evaluated using four different clustering methods with different number of clusters where some dti scalar indices for 10 human brains are processed. results the aim was to produce results with less segmentation error and a lower computational cost while attempting to minimizing boundary overlapping and minimizing the effect of artifacts due to m...

We used single-molecule imaging techniques and measured the one-dimensional diffusion of LacI repressor proteins along elongated DNA to address the long-standing puzzle of why some proteins find their targets faster than allowed by 3D diffusion. Our analysis of the LacI transcription factor's diffusion yielded four main results: (1) LacI diffuses along nonspecific sequences of DNA in the form o...

We propose a reaction-diffusion model of the mechanisms involved in the healing of cornea1 surface wounds. The model focuses on the stimulus for increased mitotic and migratory activity, specifically the role of epidermal growth factor. We determine an analytic approximation for the speed of travelling wave solutions of the model and verify the result numerically. The predicted speed compares v...

In diffusion MRI, simultaneous multi-slice single-shot EPI acquisitions have the potential to increase the number of diffusion directions obtained per unit time, allowing more diffusion encoding in high angular resolution diffusion imaging (HARDI) acquisitions. Nonetheless, unaliasing simultaneously acquired, closely spaced slices with parallel imaging methods can be difficult, leading to high ...

M. E. Zeynali [email protected] Petrochemical Synthesis Group, Petrochemical Faculty, Iran Polymer and Petrochemical Institute (IPPI), P. O. Box: 14965/115, Tehran, Iran, Abstract In this study the diffusion coefficients for reaction components were determined for unimodal and bimodal pore size distribution and assuming transitional diffusion regime using a more realistic, Stewart-Johnson, m...