337 research outputs found
Inter-species variation in the oligomeric states of the higher plant Calvin cycle enzymes glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase
In darkened leaves the Calvin cycle enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK) form a regulatory multi-enzyme complex with the small chloroplast protein CP12. GAPDH also forms a high molecular weight regulatory mono-enzyme complex. Given that there are different reports as to the number and subunit composition of these complexes and that enzyme regulatory mechanisms are known to vary between species, it was reasoned that protein-protein interactions may also vary between species. Here, this variation is investigated. This study shows that two different tetramers of GAPDH (an A2B2 heterotetramer and an A4 homotetramer) have the capacity to form part of the PRK/GAPDH/CP12 complex. The role of the PRK/GAPDH/CP12 complex is not simply to regulate the 'non-regulatory' A4 GAPDH tetramer. This study also demonstrates that the abundance and nature of PRK/GAPDH/CP12 interactions are not equal in all species and that whilst NAD enhances complex formation in some species, this is not sufficient for complex formation in others. Furthermore, it is shown that the GAPDH mono-enzyme complex is more abundant as a 2(A2B2) complex, rather than the larger 4(A2B2) complex. This smaller complex is sensitive to cellular metabolites indicating that it is an important regulatory isoform of GAPDH. This comparative study has highlighted considerable heterogeneity in PRK and GAPDH protein interactions between closely related species and the possible underlying physiological basis for this is discussed. © 2011 The Author(s)
Weighing simulated galaxy clusters using lensing and X-ray
We aim at investigating potential biases in lensing and X-ray methods to
measure the cluster mass profiles. We do so by performing realistic simulations
of lensing and X-ray observations that are subsequently analyzed using
observational techniques. The resulting mass estimates are compared among them
and with the input models. Three clusters obtained from state-of-the-art
hydrodynamical simulations, each of which has been projected along three
independent lines-of-sight, are used for this analysis. We find that strong
lensing models can be trusted over a limited region around the cluster core.
Extrapolating the strong lensing mass models to outside the Einstein ring can
lead to significant biases in the mass estimates, if the BCG is not modeled
properly for example. Weak lensing mass measurements can be largely affected by
substructures, depending on the method implemented to convert the shear into a
mass estimate. Using non-parametric methods which combine weak and strong
lensing data, the projected masses within R200 can be constrained with a
precision of ~10%. De-projection of lensing masses increases the scatter around
the true masses by more than a factor of two due to cluster triaxiality. X-ray
mass measurements have much smaller scatter (about a factor of two smaller than
the lensing masses) but they are generally biased low by 5-20%. This bias is
ascribable to bulk motions in the gas of our simulated clusters. Using the
lensing and the X-ray masses as proxies for the true and the hydrostatic
equilibrium masses of the simulated clusters and averaging over the cluster
sample we are able to measure the lack of hydrostatic equilibrium in the
systems we have investigated.Comment: 27 pages, 21 figures, accepted for publication on A&A. Version with
full resolution images can be found at
http://pico.bo.astro.it/~massimo/Public/Papers/massComp.pd
A STUDY ON CLOUD COMPUTING EFFICIENT JOB SCHEDULING ALGORITHMS
cloud computing is a general term used to depict another class of system based computing that happens over the web. The essential advantage of moving to Clouds is application versatility. Cloud computing is extremely advantageous for the application which are sharing their resources on various hubs. Scheduling the errand is a significant testing in cloud condition. Typically undertakings are planned by client prerequisites. New scheduling techniques should be proposed to defeat the issues proposed by organize properties amongst client and resources. New scheduling systems may utilize a portion of the customary scheduling ideas to consolidate them with some system mindful procedures to give answers for better and more effective employment scheduling. Scheduling technique is the key innovation in cloud computing. This paper gives the study on scheduling calculations. There working regarding the resource sharing. We systemize the scheduling issue in cloud computing, and present a cloud scheduling pecking order
Synthesis, characterization, docking and antimicrobial activity studies of binuclear Co(II) and Ni(II) complexes of bis aroylhydrazone and phenanthroline
ABSTRACT. Schiff base (HL) N1,N3-bis(4-(methylthio)benzylidene)-5-nitrobenzene-1,3-dihydrazide (HL) has been prepared from condensation of 4-(methyl thio)benzaldehyde with 5-nitrobenzene-1,3-dihydrazide. Binucleated mixed ligand complexes of nickel(II) ([Ni2(L)(dmphen)2]Cl2, [Ni2(L)(phen)2]Cl2) and cobalt(II) ([Co2(HL)(dmphen)2]Cl2, [Co2(HL)(phen)2]Cl2) complexes have been synthesized from Schiff base (HL) and 1,10-phenanthroline/2,9-dimethyl-1,10-phenanthroline. The synthesized compounds have been characterized by elemental analysis, 1H-NMR, 13C-NMR, FT-IR, UV-Visible, magnetic moment, SEM, powder X-ray diffraction and molar conductivity measurements. Further, the Schiff base and its metal complexes have been investigated for fluorescence activity and molecular docking studies. In addition, Schiff base and its metal complexes were screened for antimicrobial activity against bacteria: Escherichia coli, Bacillus subtilis and fungi: Sclerotium rolfsii and Macrophomina phaseolina.
KEY WORDS: Growth inhibitors, Ternary complex, Tuberculosis, Fluorescence activity, Crystal system
Bull. Chem. Soc. Ethiop. 2021, 35(3), 499-511.
DOI: https://dx.doi.org/10.4314/bcse.v35i3.
Engineering Silicon Nanocrystals: Theoretical study of the effect of Codoping with Boron and Phosphorus
We show that the optical and electronic properties of nanocrystalline silicon
can be efficiently tuned using impurity doping. In particular, we give
evidence, by means of ab-initio calculations, that by properly controlling the
doping with either one or two atomic species, a significant modification of
both the absorption and the emission of light can be achieved. We have
considered impurities, either boron or phosphorous (doping) or both (codoping),
located at different substitutional sites of silicon nanocrystals with size
ranging from 1.1 nm to 1.8 nm in diameter. We have found that the codoped
nanocrystals have the lowest impurity formation energies when the two
impurities occupy nearest neighbor sites near the surface. In addition, such
systems present band-edge states localized on the impurities giving rise to a
red-shift of the absorption thresholds with respect to that of undoped
nanocrystals. Our detailed theoretical analysis shows that the creation of an
electron-hole pair due to light absorption determines a geometry distortion
that in turn results in a Stokes shift between adsorption and emission spectra.
In order to give a deeper insight in this effect, in one case we have
calculated the absorption and emission spectra going beyond the single-particle
approach showing the important role played by many-body effects. The entire set
of results we have collected in this work give a strong indication that with
the doping it is possible to tune the optical properties of silicon
nanocrystals.Comment: 14 pages 19 figure
Measuring the three-dimensional shear from simulation data, with applications to weak gravitational lensing
We have developed a new three-dimensional algorithm, based on the standard
PM method, for computing deflections due to weak gravitational lensing. We
compare the results of this method with those of the two-dimensional planar
approach, and rigorously outline the conditions under which the two approaches
are equivalent. Our new algorithm uses a Fast Fourier Transform convolution
method for speed, and has a variable softening feature to provide a realistic
interpretation of the large-scale structure in a simulation. The output values
of the code are compared with those from the Ewald summation method, which we
describe and develop in detail. With an optimal choice of the high frequency
filtering in the Fourier convolution, the maximum errors, when using only a
single particle, are about 7 per cent, with an rms error less than 2 per cent.
For ensembles of particles, used in typical -body simulations, the rms
errors are typically 0.3 per cent. We describe how the output from the
algorithm can be used to generate distributions of magnification, source
ellipticity, shear and convergence for large-scale structure.Comment: 22 pages, latex, 11 figure
Discovering study-specific gene regulatory networks
This article has been made available through the Brunel Open Access Publishing Fund.Microarrays are commonly used in biology because of their ability to simultaneously measure thousands of genes under different conditions. Due to their structure, typically containing a high amount of variables but far fewer samples, scalable network analysis techniques are often employed. In particular, consensus approaches have been recently used that combine multiple microarray studies in order to find networks that are more robust. The purpose of this paper, however, is to combine multiple microarray studies to automatically identify subnetworks that are distinctive to specific experimental conditions rather than common to them all. To better understand key regulatory mechanisms and how they change under different conditions, we derive unique networks from multiple independent networks built using glasso which goes beyond standard correlations. This involves calculating cluster prediction accuracies to detect the most predictive genes for a specific set of conditions. We differentiate between accuracies calculated using cross-validation within a selected cluster of studies (the intra prediction accuracy) and those calculated on a set of independent studies belonging to different study clusters (inter prediction accuracy). Finally, we compare our method's results to related state-of-the art techniques. We explore how the proposed pipeline performs on both synthetic data and real data (wheat and Fusarium). Our results show that subnetworks can be identified reliably that are specific to subsets of studies and that these networks reflect key mechanisms that are fundamental to the experimental conditions in each of those subsets
The Qatar Biobank: background and methods
Background: The Qatar Biobank aims to collect extensive lifestyle, clinical, and biological information from up to
60,000 men and women Qatari nationals and long-term residents (individuals living in the country for â„15 years)
aged â„18 years (approximately one-fifth of all Qatari citizens), to follow up these same individuals over the long
term to record any subsequent disease, and hence to study the causes and progression of disease, and disease
burden, in the Qatari population.
Methods: Between the 11th-December-2012 and 20th-February-2014, 1209 participants were recruited into the pilot
study of the Qatar Biobank. At recruitment, extensive phenotype information was collected from each participant,
including information/measurements of socio-demographic factors, prevalent health conditions, diet, lifestyle,
anthropometry, body composition, bone health, cognitive function, grip strength, retinal imaging, total body dual
energy X-ray absorptiometry, and measurements of cardiovascular and respiratory function. Blood, urine, and saliva
were collected and stored for future research use. A panel of 66 clinical biomarkers was routinely measured on
fresh blood samples in all participants. Rates of recruitment are to be progressively increased in the coming period
and the recruitment base widened to achieve a cohort of consented individuals broadly representative of the
eligible Qatari population. In addition, it is planned to add additional measures in sub-samples of the cohort,
including Magnetic Resonance Imaging (MRI) of the brain, heart and abdomen.
Results: The mean time for collection of the extensive phenotypic information and biological samples from each
participant at the baseline recruitment visit was 179 min. The 1209 pilot study participants (506 men and 703
women) were aged between 28â80 years (median 39 years); 899 (74.4 %) were Qatari nationals and 310 (25.6 %)
were long-term residents. Approximately two-thirds of pilot participants were educated to graduate level or above.
Conclusions: The pilot has proven that recruitment of volunteers into the Qatar Biobank project with intensive
baseline measurements of behavioural, physical, and clinical characteristics is well accepted and logistically feasible.
Qatar Biobank will provide a powerful resource to investigate the major determinants of ill-health and well-being in
Qatar, providing valuable insights into the current and future public health burden that faces the country.Qatar Foundation for Education, Science and Community Development and the Supreme Council of Healt
Cleaning of ceramic membranes for produced water filtration
The application of ceramic microfiltration membranes to the tertiary treatment of produced water from an Arabian Gulf oilfield has been studied using a dedicated pilot plant. Studies were based on a previously published protocol in which the retentate stream was recycled so as to successively increase the feed concentration throughout the experimental run. Chemical cleaning in place (CIP) was applied between each run and the flux and permeability recovery recorded for various cleaning protocols studied, the CIP being based on the combination of caustic soda (NaOH) and citric acid. Surface analysis of the membrane, and specifically its hydrophilicity, was also conducted.
Results indicated the main influencing factor on permeability recovery from the CIP to be the employment of backflushing during the CIP itself. A final flux of 700âŻLâŻmâ2âŻhâ1 was sustained through the application of 6âŻwt% NaOH with 6âŻwt% citric acid combined with backflushing at approximately twice the rate of the filtration cycle flux. A consideration of the impact of this flux value on the viability of two commercially-available ceramic membrane technologies indicated the footprint incurred to be slightly lower than that of the upstream induced gas flotation technology and corroborated a previously published estimate. The flux was sustained despite surface analysis indicating a loss of the innate hydrophilicity of the ceramic membrane
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