7,154 research outputs found

    Exploratory Study on Selected Philippine Agricultural Commodity Import Statistics vis-à-vis Export Statistics of the Exporting Countries

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    Using the import data compiled by the Philippines and comparing these with data as reported by the exporting countries, this study aims to determine the disparity of the statistics from the two sources on the quantity and value of selected agricultural commodities for the years 2000 to 2005. The products covered by this study consist of wholly or semi-milled rice, maize (corn), live poultry, domestic fowls, ducks, geese, frozen meat of bovine animals, apples, oranges, onions and shallots, and garlic. The differences in statistics on the bilateral transactions─in terms of FOB values, quantities, and derived unit prices─are examined by using percentage differences, the implicit minimal measurement error (IMME), and the Wilcoxon Matched-Pair Signed-Ranks (Wilcoxon-MPSR) test. Results show that considerable discrepancies between import and export statistics do exist. The discrepancy may reflect both legitimate conceptual differences between Philippine imports and exports statistics of the exporting countries, as well as errors in reporting. The discrepancy is further substantiated by the results of the Wilcoxon-MPSR test, which show that these differences are significant.

    \u3cem\u3eβ\u3c/em\u3e-Homopipitzolone

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    The structure of β-homopipitzolone (one of the two isomers of an intermediate product in the homocedrole synthesis) has been unequivocally established as 1 O-hydroxy-2,6,9-trimetbyltricyclo[6.3.1.01,6] dodeca-9-ene-5, II, 12-trione with relative IR,2R,6R,8S configuration

    Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

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    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ∼ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated. © Published under licence by IOP Publishing Ltd

    The contribution of ultracompact dark matter minihalos to the isotropic radio background

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    The ultracompact minihalos could be formed during the earlier epoch of the universe. The dark matter annihilation within them is very strong due to the steep density profile, ρr2.25\rho \sim r^{-2.25}. The high energy electrons and positrons from the dark matter annihilation can inverse Compton scatter (ICS) with the background photons, such as CMB photons, to acquire higher energy. On the other hand, the synchrotron radiation can also be produced when they meet the magnetic field. In this paper, we study the signals from the UCMHs due to the dark matter annihilation for the radio, X-ray and γ\gamma-ray band. We found that for the radio emission the UCMHs can provide one kind of source for the radio excess observed by ARCADE 2. But the X-ray signals due to the ICS effect or the γ\gamma-ray signals mainly due to the prompt emission from dark matter would exceed the present observations, such as Fermi, COMPTEL and CHANDRA. We found that the strongest limits on the fraction of UCMHs come from the X-ray observations and the constraints from the radio data are the weakest.Comment: 6 pages, 8 figures, Comments Welcome! Some Refs. are added, some presentation have been corrected. The conclusions remain unchanged. One important reference has been corrected. Some presentations are changed and added according to the referee's comments. Accepted for publication in PR

    The Evolution of NGC 7027 at Radio Frequencies: A New Determination of the Distance and Core Mass

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    We present the results of a 25-year program to monitor the radio flux evolution of the planetary nebula NGC7027. We find significant evolution of the spectral flux densities. The flux density at 1465 MHz, where the nebula is optically thick, is increasing at a rate of 0.251+-0.015 % per year, caused by the expansion of the ionized nebula. At frequencies where the emission is optically thin, the spectral flux density is changing at a rate of -0.145+-0.005 % per year, caused by a decrease in the number of ionizing photons coming from the central star. A distance of 980+-100 pc is derived. By fitting interpolated models of post-AGB evolution to the observed changes, we find that over the 25-yr monitoring period, the stellar temperature has increased by 3900+-900 K and the stellar bolometric luminosity has decreased by 1.75+-0.38 %. We derive a distance-independent stellar mass of 0.655+-0.01 solar masses adopting the Bloecker stellar evolution models, or about 0.04 solar masses higher when using models of Vassiliadis & Wood which may provide a better fit. A Cloudy photoionization model is used to fit all epochs at all frequencies simultaneously. The differences between the radio flux density predictions and the observed values show some time-independent residuals of typically 1 %. A possible explanation is inaccuracies in the radio flux scale of Baars et al. We propose an adjustment to the flux density scale of the primary radio flux calibrator 3C286, based on the Cloudy model of NGC7027. We also calculate precise flux densities for NGC7027 for all standard continuum bands used at the VLA, as well as for some new 30GHz experiments.Comment: submitted to the Astrophysical Journa

    Rural Hispanic Youths\u27 Perceptions of Positive Youth Development Experiences

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    An exploratory study examined rural Latino youths\u27 perceptions regarding positive youth development (PYD), particularly related to aspects such as the definition of PYD, potential benefits of PYD, and motivations for participating in PYD activities. A total of 28 self-identified Hispanic youths participated in focus groups. Findings suggest that participants identified key components of PYD (e.g., skills gained through participation) that are generally consistent with broader research on the topic. Youths\u27 motivations for participating in PYD programs included familial encouragement, availability of the programs, and the engaging/enjoyable nature of the programs. Potential implications for Extension professionals are discussed

    Characterisation of ATP-dependent Mur ligases involved in the biogenesis of cell wall peptidoglycan in Mycobacterium tuberculosis.

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    ATP-dependent Mur ligases (Mur synthetases) play essential roles in the biosynthesis of cell wall peptidoglycan (PG) as they catalyze the ligation of key amino acid residues to the stem peptide at the expense of ATP hydrolysis, thus representing potential targets for antibacterial drug discovery. In this study we characterized the division/cell wall (dcw) operon and identified a promoter driving the co-transcription of mur synthetases along with key cell division genes such as ftsQ and ftsW. Furthermore, we have extended our previous investigations of MurE to MurC, MurD and MurF synthetases from Mycobacterium tuberculosis. Functional analyses of the pure recombinant enzymes revealed that the presence of divalent cations is an absolute requirement for their activities. We also observed that higher concentrations of ATP and UDP-sugar substrates were inhibitory for the activities of all Mur synthetases suggesting stringent control of the cytoplasmic steps of the peptidoglycan biosynthetic pathway. In line with the previous findings on the regulation of mycobacterial MurD and corynebacterial MurC synthetases via phosphorylation, we found that all of the Mur synthetases interacted with the Ser/Thr protein kinases, PknA and PknB. In addition, we critically analyzed the interaction network of all of the Mur synthetases with proteins involved in cell division and cell wall PG biosynthesis to re-evaluate the importance of these key enzymes as novel therapeutic targets in anti-tubercular drug discovery
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