3,139 research outputs found

    Hyperforin: A lead for antidepressants

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    Depression is a complex but treatable disorder if diagnosed appropriately. However, despite the advances in the understanding of the molecular basis of this disorder and the vast range of medication, psychotherapy and electroconvulsive therapy, very safe and effective drug to treat this disease is still being sought. Several studies suggest that St.John’s wort (Hypericum perforatum L.) has phloroglucinol derivative, hyperforin, exhibiting antidepressant activity. This bioactive component can be exploited to create a major shift in the safer treatment of depression. Keywords: Hypericum perforatum L., St. John's wort, Antidepressant, Hyperfori

    Mixture Models for Photometric Redshifts

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    Determining photometric redshifts to high accuracy is paramount to measure distances in wide-field cosmological experiments. With only photometric information at hand, photo-zs are prone to systematic uncertainties in the intervening extinction and the unknown underlying spectral-energy distribution of different astrophysical sources. Here, we aim to resolve these model degeneracies and obtain a clear separation between intrinsic physical properties of astrophysical sources and extrinsic systematics. We aim at estimates of the full photo-z probability distributions, and their uncertainties. We perform a probabilistic photo-z determination using Mixture Density Networks (MDN). The training data-set is composed of optical (grizgriz) point-spread-function and model magnitudes and extinction measurements from the SDSS-DR15, and WISE midinfrared (3.4μ3.4 \mum and 4.6μ4.6 \mum) model magnitudes. We use Infinite Gaussian Mixture models to classify the objects in our data-set as stars, galaxies or quasars, and to determine the number of MDN components to achieve optimal performance. The fraction of objects that are correctly split into the main classes is 94%. Our method improves the bias of photometric redshift estimation (i.e. the mean Δz\Delta z = (zp - zs)/(1 + zs)) by one order of magnitude compared to the SDSS photo-z, and decreases the fraction of 3σ3 \sigma outliers (i.e. 3rms(Δz)<Δz(\Delta z) < \Delta z). The relative, root-mean-square systematic uncertainty in our resulting photo-zs is down to 1.7% for low-redshift galaxies (zs << 0.5). We have demonstrated the feasibility of machine-learning based methods that produce full probability distributions for photo-z estimates with a performance that is competitive with state-of-the art techniques. Our method can be applied to wide-field surveys where extinction can vary significantly across the sky and with sparse spectroscopic calibration samples.Comment: 14 pages, 9 figures, 7 tables, submitted to A&A 14/10/202

    A Partner Evokes Latent Differences between Hox Proteins

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    Hox transcription factors bind highly related DNA sequences in vitro, yet they regulate different genes and play distinct roles in anterior-posterior patterning in animals. Slattery et al. report that a common cofactor, Exd, accentuates latent sequence specificities of all eight Hox proteins and directs binding to relevant sites across the genome

    Har Gobind Khorana 1922–2011

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    Temperature-sensitive protein–DNA dimerizers

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    Programmable DNA-binding polyamides coupled to short peptides have led to the creation of synthetic artificial transcription factors. A hairpin polyamide-YPWM tetrapeptide conjugate facilitates the binding of a natural transcription factor Exd to an adjacent DNA site. Such small molecules function as protein-DNA dimerizers that stabilize complexes at composite DNA binding sites. Here we investigate the role of the linker that connects the polyamide to the peptide. We find that a substantial degree of variability in the linker length is tolerated at lower temperatures. At physiological temperatures, the longest linker tested confers a "switch"-like property on the protein-DNA dimerizer, in that it abolishes the ability of the YPWM moiety to recruit the natural transcription factor to DNA. These observations provide design principles for future artificial transcription factors that can be externally regulated and can function in concert with the cellular regulatory circuitry

    A looking-out portal (LOP) approach to enhance qualitative aspects of bandwidth utilisation in academic networks

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    Campuses of educational institutions periodically need to increase network bandwidth to keep up with increased demand and this decision is based on the quantitative aspects of the network bandwidth utilisation. The qualitative utilisation of the bandwidth is seldom looked into. Improving the qualitative utilisation of the bandwidth may not even necessitate a network upgrade. Although blacklist-based access control techniques help to a certain degree, the findings of this research indicate otherwise. A multi-tier, whitelist-based, looking-out portal (LOP) approach is presented that promises to improve the qualitative utilisation of the network while positively impacting pertinent resource identification and location of sources on the internet. The authors draw on their years of experience serving as students and staff in various campuses of universities and colleges in various countries while making recommendations

    Identification of polymorphism in promoter region of growth hormone receptor (GHR) gene and its association with milk related traits in Holstein cows

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    It is widely accepted that hormones, growth factors and other agents exert their biological effects on target tissues by binding to specific receptors on the plasma membrane. The variability in constituent sequences of growth hormone receptor (GHR) gene is very important because of its major role in mammary gland development. The aim of the present study is to detect polymorphism in promoter region of GHR gene and its association with milk related traits in Holstein cows. Blood samples were randomly collected from 93 Holstein cows, transported to the laboratory and stored at -20°C for further analysis. DNA was extracted using modified salting-out method and a fragment of 836 base pair from promoter region of GHR gene was amplified by a specific primer pairs using polymerase chain reaction (PCR). The PCR products were digested by AluI restriction enzyme and electrophoresed on 2% agarose gel. Result of enzyme digestion for GHR gene, showed allele AluI(-) with the fragment sizes of 14, 75 and 747, and allele AluI(+) with the fragment sizes of 14, 75, 145 and 602 base pairs. Frequency estimation of AluI(-) and AluI(+) alleles were 56 and 44%, respectively, and mean of heterozygosity was 0.49. Statistical analysis showed that cows with AluI(+) allele had significantly higher milk protein and fat percentage at first lactation compared with cows with AluI(-/-), while there was no significant relation between different genotypes and other traits.Keywords: Growth hormone receptor, polymorphism, milk, HolsteinAfrican Journal of Biotechnology Vol. 9(33), pp. 5460-5464, 16 August, 201

    Development of a life cycle assessment tool for the assessment of food production systems within the energy, water and food nexus

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    © 2015 The Institution of Chemical Engineers.As the demand for services and products continues to increase in light of rapid population growth, the question of energy, water and food (EWF) security is of increasing importance. The systems representing the three resources are intrinsically connected and, as such, there is a need to develop assessment tools that consider their interdependences. Specifically when evaluating the environmental performance of a food production system, it is necessary to understand its life cycle. The objective of this paper is to introduce an integrated energy, water and food life cycle assessment tool that integrates EWF resources in one robust model and at an appropriate resolution. The nexus modelling tool developed is capable of providing an environmental assessment for food production systems utilising a holistic systems approach as described by a series of subsystems that constitute each of the EWF resources. A case study set in Qatar and characterised by an agriculture sub-system, which includes the production and application of fertilisers and the raising of livestock, a water sub-system represented by mechanical and thermal desalination processes and an energy sub-system, which includes fossil fuel in the form of combined cycle natural gas based energy production and solar renewable energy is used to illustrate the model function. For the nexus system analysed it is demonstrated that the food system is the largest contributor to global warming. The GWP can be reduced by up to 30% through the utilisation of solar energy to substitute fossil fuels, which, however, comes with a significant requirement for land investment
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