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Directed Information, Causal Estimation, and Communication in Continuous Time
Weissman, T.,Young-Han Kim,Permuter, H. H. IEEE 2013 IEEE transactions on information theory Vol.59 No.3
<P>A notion of directed information between two continuous-time processes is proposed. A key component in the definition is taking an infimum over all possible partitions of the time interval, which plays a role no less significant than the supremum over “space” partitions inherent in the definition of mutual information. Properties and operational interpretations in estimation and communication are then established for the proposed notion of directed information. For the continuous-time additive white Gaussian noise channel, it is shown that Duncan's classical relationship between causal estimation error and mutual information continues to hold in the presence of feedback upon replacing mutual information by directed information. A parallel result is established for the Poisson channel. The utility of this relationship is demonstrated in computing the directed information rate between the input and output processes of a continuous-time Poisson channel with feedback, where the channel input process is constrained to be constant between events at the channel output. Finally, the capacity of a wide class of continuous-time channels with feedback is established via directed information, characterizing the fundamental limit on reliable communication.</P>
Antimicrobial Activity of Greater Galangal [Alpinia galanga (Linn.) Swartz.] Flowers
Wei-Yea Hsu,Amarat Simonne,Alexandra Weissman,김정목 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.4
Using the agar disc diffusion method, the potential antimicrobial activity of edible galangal [Alpinia galanga (Linn.) Swartz.] flower against Salmonella,Escherichia coli O157:H7, Listeria monocytogenes,Staphylococcus aureus, and Shigella, and the effects of different drying methods and solvent types on the flowers’antimicrobial activity were investigated. Oven-dried ethanol (OD Ethanol) extract from galangal flower was the most effective against S. aureus with inhibition zone of about 26-31 mm and the minimum inhibitory concentration (MIC) ranging from 0.352-0.547 mg/mL. No antimicrobial activity was observed on E. coli O157:H7 and Salmonella. Overall antimicrobial activity of oven-dried samples extracted with ethanol (OD Ethanol) was the highest with inhibition zone of 8.94 mm and MIC of 1.457 mg/mL. In contrast,freeze-dried samples extracted with ethanol (FD Ethanol)exhibited the lowest overall antimicrobial activity (7.05mm and 2.470 mg/mL). This is the first report describing antimicrobial activity of galangal flowers against Gram-positive S. aureus.
Kim, Young-Eun,Lee, Minji,Gu, Hyejung,Kim, Jeongwoo,Jeong, Seongju,Yeo, Sujin,Lee, You Jeong,Im, Sin-Hyeog,Sung, Young-Chul,Kim, Hak Jae,Weissman, Irving L.,Ahn, G-One The Company of Biologists Ltd 2018 Disease models & mechanisms Vol.11 No.7
<P><B>ABSTRACT</B></P><P>Inflammatory bowel disease (IBD) is a chronic inflammatory disease, in which the intestinal epithelium loses its barrier function. Given the existence of the oxygen gradient in the intestinal epithelium and that inflammation further contributes to the tissue hypoxia, we investigated the role of hypoxia-inducible factor (HIF), a transcription factor activated under hypoxic conditions in myeloid cells, in the progression of IBD. To do this, we utilized myeloid-specific knockout (KO) mice targeting HIF pathways, created by a Cre-loxP system with human MRP8 (hMRP8), an intracellular calcium-binding protein, as the myeloid promoter. By feeding 5% dextran sodium sulfate (DSS) to hMRP8 von Hippel Lindau (<I>Vhl</I>) KO mice, in which HIF-1α and HIF-2α are constitutively activated in myeloid cells, we found that these mice were highly susceptible to DSS-induced colitis, demonstrating greater body weight loss, increased mortality, faster onset of rectal bleeding, shortened colon length, and increased CD11b- or Gr-1-positive myeloid cells in the colon compared with wild-type (WT) mice. These parameters were restored to, if not better than, the WT levels when we examined hMRP8 <I>Hif-1a</I> KO mice upon 5% DSS feeding. hMRP8 <I>Hif-2a</I> KO mice, on the other hand, exhibited a similar degree of DSS-induced colitis to that of WT mice. Lastly, when DSS was given together with azoxymethane to induce tumorigenesis in the colon, we found that hMRP8 <I>Hif-1a</I> KO mice exhibited comparable levels of colorectal tumors to those of WT mice, indicating that HIF-1α in myeloid cells is dispensable for tumorigenesis. Collectively, our results suggest that HIF-1α activation in myeloid cells critically regulates IBD progression.</P>