Adaptive importance sampling technique for markov chains using stochastic approximation

For a discrete-time finite-state Markov chain, we develop an adaptive importance sampling scheme to estimate the expected total cost before hitting a set of terminal states. This scheme updates the change of measure at every transition using constant or decreasing step-size stochastic approximation. The updates are shown to concentrate asymptotically in a neighborhood of the desired zero-variance estimator. Through simulation experiments on simple Markovian queues, we observe that the proposed technique performs very well in estimating performance measures related to rare events associated with queue lengths exceeding prescribed thresholds. We include performance comparisons of the proposed algorithm with existing adaptive importance sampling algorithms on some examples. We also discuss the extension of the technique to estimate the infinite horizon expected discounted cost and the expected average cost

Quantitative and qualitative assessment of plankton: some ecological aspect and water quality parameters of the river Meghna, Bangladesh

Investigation on the seasonal distribution and abundance of various major taxa of phyto and zooplankton and the corresponding physico-chemical characteristics were carried out in four selected stations between the latitude 22°35.494N N-23°23.987 N and longitude 90°35.793 E- 90°49.061 E of the Meghna river system, Bangladesh. Drop count method was followed for the qualitative and quantitative analysis of both phyto- and zooplankton. A total of 41 phytoplankton genera belonging to 17 families and 13 zooplankton genera belonging to 11 families were recorded. Zooplankton growth cycle was noticeably less (3.0%) than the phytoplankton abundance almost throughout the study period. Quantity of plankton registered to increase chronologically from the upper to lower stretches of the river. During summer investigation the load of phytoplankton was recorded maximum (11,300-51,850 No/1). Ratio-wise quantitative difference between zoo- and phytoplankton in composition of the total standing crop fluctuated between 1.0:5.5 and 1:1037. Among the phytoplanktonic groups, Chlorophyceae was found to be dominating (95.0%) in all sampling stations. Protococcus, a single genus of Chlorophyceae played a unique role during summer, contributing the highest density of about 74.0%. The pattern of qualitative and quantitative difference of plankton standing crop in different sampling sites can be attributed to the existing physico-chemical characteristics, mainly water temperature, pH and hardness

Ecology of Shakla heel (Brahmanbaria), Bangladesh

The bed Shakla, comprising an average area of 75.0 ha is located in the northeastern region (Brahmanbaria district) of Bangladesh. The study was carried out to assess the ecological aspects of bed ecosystem. Surface run-off and increase inflow of rain water from the upper stretch during monsoon cause inundation and resumption of connection between beel and parent rivers. The range of dissolved oxygen (DO) content ( 4.5-8.9 mg/L) was found congenial for aquatic life. pH was in the alkaline range (7.3-8.5) and free C02 was reletavely high. Lower values of total hardness and total alkalinity indicated less nutrients in the beel water. A wide variation (1.4-27.2 x 103 ceHs/L) in the standing crop of total plankton was recorded during study period of which phytoplankton alone contributed about 90%. Phytoplankton diversity in the beel represented by three groups viz. Chlorophyceae, Myxophyceae and Bacillariophyceae in order of abundance. A total of 52 fish species belonging to 36 genera, 20 families and 1 species of prawn were identified so far from the beel. About l3 types of fishing method were found in operation. Seine nets (moshari berja, ghono berjal) and gill net (current jal) were identified as detrimental gear killing juveniles of different species during post spawning period. Kua fishing was also found harmful due to dewatering nature. A total of 11 species belonging to 11 genera and 10 families of aquatic weeds were identified from the beet The eggs of Macrobrachium Jamarrei were identified into the Najas najas vegetation during April-September

C3a Enhances Nerve Growth Factor-Induced NFAT Activation and Chemokine Production in a Human Mast Cell Line, HMC-1

Activation of cell surface G protein-coupled receptors leads to transphosphorylation and activation of a number of receptor tyrosine kinases. Human mast cells express G protein-coupled receptors for the complement component C3a (C3aR) and high affinity nerve growth factor (NGF) receptor tyrosine kinase, TrkA. To determine whether C3a cross-regulates TrkA signaling and biological responses, we used a human mast cell-line, HMC-1, that natively expresses both receptors. We found that NGF caused tyrosine phosphorylation of TrkA, resulting in a sustained Ca2+ mobilization, NFAT activation, extracellular-signal regulated kinase (ERK) phosphorylation, and chemokine, macrophage inflammatory protein-1β (MIP-1β) production. In contrast, C3a induced a transient Ca2+ mobilization and ERK phosphorylation but failed to stimulate TrkA phosphorylation, NFAT activation, or MIP-1β production. Surprisingly, C3a significantly enhanced NGF-induced NFAT activation, ERK phosphorylation, and MIP-1β production. Pertussis toxin, a Gi/o inhibitor, selectively blocked priming by C3a but had no effect on NGF-induced responses. Mitogen-activated protein/ERK kinase inhibitor U0126 caused ∼30% inhibition of NGF-induced MIP-1β production but had no effect on priming by C3a. However, cyclosporin A, an inhibitor of calcineurin-mediated NFAT activation, caused substantial inhibition of NGF-induced MIP-1β production both in the absence and presence of C3a. These data demonstrate that NGF caused tyrosine phosphorylation of TrkA to induce chemokine production in HMC-1 cells via a pathway that mainly depends on sustained Ca2+ mobilization and NFAT activation. Furthermore, C3a enhances NGF-induced transcription factor activation and chemokine production via a G protein-mediated pathway that does not involve TrkA phosphorylation

Premade Nanoparticle Films for the Synthesis of Vertically Aligned Carbon Nanotubes

Carbon nanotubes (CNTs) offer unique properties that have the potential to address multiple issues in industry and material sciences. Although many synthesis methods have been developed, it remains difficult to control CNT characteristics. Here, with the goal of achieving such control, we report a bottom-up process for CNT synthesis in which monolayers of premade aluminum oxide (Al2O3) and iron oxide (Fe3O4) nanoparticles were anchored on a flat silicon oxide (SiO2) substrate. The nanoparticle dispersion and monolayer assembly of the oleic-acid-stabilized Al2O3 nanoparticles were achieved using 11-phosphonoundecanoic acid as a bifunctional linker, with the phosphonate group binding to the SiO2 substrate and the terminal carboxylate group binding to the nanoparticles. Subsequently, an Fe3O4 monolayer was formed over the Al2O3 layer using the same approach. The assembled Al2O3 and Fe3O4 nanoparticle monolayers acted as a catalyst support and catalyst, respectively, for the growth of vertically aligned CNTs. The CNTs were successfully synthesized using a conventional atmospheric pressure-chemical vapor deposition method with acetylene as the carbon precursor. Thus, these nanoparticle films provide a facile and inexpensive approach for producing homogenous CNTs

Design and Development of Gliclazide Matrix Tablets Using HPC, HPMC and their Combination as a Release Retarding Polymers

In present investigation an attempt has been made to design and develop some Gliclazide matrix tablets using Hydroxy propyl cellulose, Hydroxy propyl methyl cellulose and their combination as release retarding polymers. Gliclazide is oral hypoglycaemic drug which lowers blood glucose level and has been selected to prepare sustained release dosage forms. Gliclazide sustained release matrix tablets were prepared using Hydorxy Propyl Cellulose, Hydroxy Propyl Methyl Cellulose and their combination as base polymer by wet granulation method. FT-IR spectral analysis showed that characteristic peak of Gliclazide pure drug was retained in the spectra of all the formulations indicating the inactness of the drug in all the formulations. The prepared tablets were evaluated for number of parameters like thickness, diameter, weight variation, swelling index and in vitro release studies. All the prepared tablets were of smooth surface and elegant texture. The tablets prepared were checked visually for its appearance & surface texture. The weights of the tablets were in the range of 250 ± 5 mg. The thickness of the tablet was in the range of 4.45 ± 0.11 mm to 4.51 ± 0.12 mm Gliclazide matrix tablets formulated employing HPMC K-4M and combination of HPMC K-4M and HPC 75-100 provided slow and controlled release of Gliclazide up to 12 hr. Drug release from the matrix tablets formulation containing HPMC K-4M and HPC 75-100 follows first order drug release with non-fickian diffusion. All the tablet formulation showed compliance with pharmacopoeial standard. As the time increases, the swelling index was increased; later on it decreases Gradually due to dissolution of outermost –gelled layer of tablet into dissolution medium. Comparison between HPMC K-4M, HPC 75-100 and their combination it has been observed that swelling index of HPMC K-4M was significantly more compared to HPC 75-100. Whereas swelling index in case of HPC 75-100 is less as compare to HPMC K-4M and HPC 75-100 combination. The dissolution result shows that an increased amount of polymer resulted in reduced drug release. A concentration dependent drug release is evident in case of the polymer i.e., lower concentration of polymers, release is marginally retarded at higher concentration is considerable. Prepared matrix formulation containing HPMC K-4M (F6 ), HPMC K-4M and HPC 75-100 combination (F9 ) probably showing better release based up to 98 % to 99 % drug release within 12 hour

Platelet-Activating Factor-Induced Chemokine Gene Expression Requires NF-κB Activation and Ca2+/calcineurin Signaling Pathways: Inhibition by Receptor Phosphorylation and β-Arrestin Recruitment

Previously, we reported that platelet-activating factor (PAF) stimulates higher G protein activation and a more robust Ca2+ mobilization in RBL-2H3 cells expressing earboxyl terminus deletion, phosphorylation-deficient mutant of PAF receptor (mPAFR) when compared with the wild-type receptor (PAFR). However, PAF did not provide sufficient signal for CC chemokine receptor ligand 2 (CCL2) production in cells expressing mPAFR. Based on these findings, we hypothesized that receptor phosphorylation provides a G protein-independent signal that synergizes with Ca2+ mobilization to induce CCL2 production. Here, we show that a mutant of PAFR (D289A), which does not couple to G proteins, was resistant to agonist-induced receptor phosphorylation. Unexpectedly, we found that when this mutant was coexpressed with mPAFR, it restored NF-κB activation and CCL2 production. PAF caused translocation of β-arrestin from the cytoplasm to the membrane in cells expressing PAFR but not a phosphorylation-deficient mutant in which all Ser/Thr residues were replaced with Ala (AST-PAFR). Interestingly, PAF induced significantly higher NF-κB and nuclear factor of activated T cells (NFAT)-luciferase activity as well as CCL2 production in cells expressing ΔST-PAFR than those expressing PAFR. Furthermore, a Ca2+/calcineurin inhibitor completely inhibited PAF-induced NFAT activation and CCL2 production but not NF-κB activation. These findings suggest that the carboxyl terminus of PAFR provides a G protein-independent signal for NF-κB activation, which synergizes with G protein-mediated Ca2+/calcineurin activation to induce CCL2 production. However, receptor phosphorylation and β-arrestin recruitment inhibit CCL2 production by blocking both NF-κB activation and Ca 2+/calcineurin-dependent signaling pathway

Sedimentation and Watershed Management Of Krishnagiri Reservoir, India

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Regeneration of plantlets from nodal and shoot tip explants of Anoectochilus elatus Lindley, an endangered terrestrial orchid

Anoectochilus elatus Lindley is an endangered terrestrial orchid. A procedure for the regeneration of complete plantlets of A. elatus Lindley through node and shoot tip explants resulted directly in shoots when cultured on a full strength Murashige and Skoog (1962) medium supplemented with cytokinins at different concentrations. An average number of shoots per explant is 3 in shoot tip and 4 in node, respectively. The best shoot proliferation was observed in 3.0 mg/l 1-phenyl-3-(1,2,3-thiadiazol-5-yl)-urea (TDZ) and the mean shoot length in 3.5 mg/l 6-furfurylaminopurine (KIN) (node) and 0.01 mg/l (shoot tip). Hundred percent rooting was achieved with the regenerated shoots in the same medium with the addition of 0.3 g/l activated charcoal (AC). Plantlets with well developed leaves and roots were transplanted to pots filled with a mixture of coconut coir, activated charcoal, commercial fertilizers (3:1:1) and acclimatized before been transferred to the greenhouse.Keywords: : Anoectochilus elatus, activated charcoal, regeneration, rootingAfrican Journal of Biotechnology Vol. 11(29), pp. 7549-7553, 10 April, 201