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Seeded region growing (SRG) is a fast, effective and robust method for image segmentation. It begins with placing a set of seeds in the image to be segmented, where each seed could be a single pixel or a set of connected pixels. Then SRG grows these seeds into regions by successively adding neighbouring pixels to them. It finishes when all pixels in the image are assigned to one (and only one) region. The growing strategy of SRG implicitly assumes that pixels from the same region share the same greyvalue. As a first contribution, this study develops new modifications to SRG so that this constant greyvalue assumption is relaxed. Since the growing strategy of SRG does not impose any constraints or restrictions on the shapes of the growing regions, quite often SRG would produce very rough segmentation boundaries even the true boundaries were smooth. The second contribution of this study is the proposal of a stabilised SRG that encourages smoother boundaries and prevents the so‐called leakage problem. All these new variants are conceptually simple and easy to implement. They are tested with simulated and real images, and are shown to have better performances than the original SRG. [ABSTRACT FROM AUTHOR]

Key points The amygdala is a key brain structure implicated in processing emotions and is thought to underlie anxiety-related behaviours., Interneurons of the basolateral amygdala provide constant silencing of principal cells, and are proven to be active cellular elements during emotional processing., We report here a novel interneuron type of the amygdala, termed neurogliaform cell (NGFC), and study its function by a combination of in vivo and in vitro techniques., NGFCs provide a peculiar cell-to-cell form of communication via volume transmission of GABA., In-depth analysis of specific neuron type is likely to improve the understanding of amygdala circuits in health and disease., Abstract Synaptic inhibition in the amygdala actively participates in processing emotional information. To improve the understanding of interneurons in amygdala networks it is necessary to characterize the GABAergic cell types, their connectivity and physiological roles. We used a mouse line expressing a green fluorescent protein (GFP) under the neuropeptide Y (NPY) promoter. Paired recordings between presynaptic NPY-GFP-expressing (+) cells and postsynaptic principal neurons (PNs) of the basolateral amygdala (BLA) were performed. The NPY-GFP+ neurons displayed small somata and short dendrites embedded in a cloud of highly arborized axon, suggesting a neurogliaform cell (NGFC) type. We discovered that a NPY-GFP+ cell evoked a GABAA receptor-mediated slow inhibitory postsynaptic current (IPSC) in a PN and an autaptic IPSC. The slow kinetics of these IPSCs was likely caused by the low concentration and spillover of extracellular GABA. We also report that NGFCs of the BLA fired action potentials phase-locked to hippocampal theta oscillations in anaesthetized rats. When this firing was re-played in NPY+-NGFCs in vitro, it evoked a transient depression of the IPSCs. Presynaptic GABAB receptors and functional depletion of synaptic vesicles determined this short-term plasticity. Synaptic contacts made by recorded NGFCs showed close appositions, and rarely identifiable classical synaptic structures. Thus, we report here a novel interneuron type of the amygdala that generates volume transmission of GABA. The peculiar functional mode of NGFCs makes them unique amongst all GABAergic cell types of the amygdala identified so far. [ABSTRACT FROM AUTHOR]

This paper considers the problem of non-parametric regression using wavelet techniques. Its main contribution is the proposal of a new wavelet estimation procedure for recovering functions corrupted by correlated noise, although a similar procedure for independent noise is also presented. Two special features of the proposed procedure are that it imposes a so-called ‘tree constraint’ on the wavelet coefficients and that it uses the minimum description length principle to define its ‘best’ estimate. The proposed procedure is empirically compared with some existing wavelet estimation procedures, for the cases of independent and correlated noise. [ABSTRACT FROM AUTHOR]

IgASE1, a C18-Δ9-polyunsaturated fatty acid-specific fatty acid elongase component from Isochrysis galbana, contains a variant histidine box (his-box) with glutamine replacing the first histidine of the conserved histidine-rich motif present in all other known equivalent proteins. The importance of glutamine and other variant amino acid residues in the his-box of IgASE1 was determined by site-directed mutagenesis. Results showed that all the variation in amino acid sequence between this motif in IgASE1 and the consensus sequences of other elongase components was required for optimum enzyme activity. The substrate specificity was shown to be unaffected by these changes suggesting that components of the his-box are not directly responsible for substrate specificity. [Copyright &y& Elsevier]