Implementation of the Explicit Group Iterative Method for Solving Image Blurring Problem using Non-Linear Diffusion Equations

Diffusion equations have been known to solve various image processing problems. This study employs the diffusion equations as the partial difference equations (PDEs)-based image processing techniques for image blurring which also can be refer as the process of image smoothing. The solutions of diffusion equations were obtained using the iterative algorithms and thereafter applied in the image blurring processes. The images were blurred without destroying the crucial information of an image that need to be preserve such as sharp edges, lines and shapes as the diffusion occurs inside the image locations, where the images with different sizes were tested. In terms of performance comparison, the standard point Gauss-Seidel and two-point Explicit Group (2-EG) methods were considered to produce the same quality image of classical point iterative method which is Jacobi. The numerical results showed that 2-EG iterative method capable to smooth the inner region of the images faster compared to the standard point iterative method. It was shown that the 2-EG iterative method more efficient in reducing the number of iterations and computational time than the standard point iterative method

Cloning, sequencing, and characterization of the hexahydro-1,3,5-trinitro-1,3,5-triazine degradation gene cluster from Rhodococcus rhodochrous

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a high explosive which presents an environmental hazard as a major land and groundwater contaminant. Rhodococcus rhodochrous strain 11Y was isolated from explosive contaminated land and is capable of degrading RDX when provided as the sole source of nitrogen for growth. Products of RDX degradation in resting-cell incubations were analyzed and found to include nitrite, formaldehyde, and formate. No ammonium was excreted into the medium, and no dead-end metabolites were observed. The gene responsible for the degradation of RDX in strain 11Y is a constitutively expressed cytochrome P450-like gene, xpLA, which is found in a gene cluster with an adrenodoxin reductase homologue, xplB. The cytochrome P450 also has a flavodoxin domain at the N terminus. This study is the first to present a gene which has been identified as being responsible for RDX biodegradation. The mechanism of action of XplA on RDX is thought to involve initial denitration followed by spontaneous ring cleavage and mineralization

LUKISAN FAUNA, POLA SEBARAN DAN LANSKAP BUDAYA DI KAWASAN KARS SULAWESI BAGIAN SELATAN

Tulisan ini menyajikan studi tentang lanskap pada situs gua-gua yang memiliki gambar dari masa prasejarah. Gua-gua prasejarah di bagian selatan Pulau Sulawesi merupakan kawasan gua dengan karakter lukisan telapak tangan dan fauna. Penelitian ini difokuskan pada lukisan fauna dan lanskap budaya. Metode yang digunakan diantaranya mengumpulkan hasil penelitian lukisan di wilayah ini kemudian mengklasifikasi jenis lukisan fauna dan keletakan situs berlukis tersebut dalam peta dengan menggunakan software GIS. Software ini juga digunakan untuk menghitung jarak situs terdekat dan terjauh dengan pantai di masa Pleistosen.  Hasil identifikasi berdasarkan lukisan fauna, pola sebaran gua dan lingkungan masa lalu menjelaskan bahwa kawasan gua-gua prasejarah di bagian selatan Sulawesi merupakan lanskap budaya yang telah diokupasi oleh dua kelompok identitas yang berbeda berdasarkan karakter lukisannya

Modelling and validation of proton exchange membrane fuel cell (PEMFC)

This paper is the outcome of a small scale fuel cell project. Fuel cell is an electrochemical device that converts energy from chemical reaction to electrical work. Proton Exchange Membrane Fuel Cell (PEMFC) is one of the different types of fuel cell, which is more efficient, having low operational temperature and fast start up capability results in high energy density. In this study, a mathematical model of 1.2 W PEMFC is developed and simulated using MATLAB software. This model describes the PEMFC behaviour under steady-state condition. This mathematical modeling of PEMFC determines the polarization curve, power generated, and the efficiency of the fuel cell. Simulation results were validated by comparing with experimental results obtained from the test of a single PEMFC with a 3 V motor. The performance of experimental PEMFC is little lower compared to simulated PEMFC, however both results were found in good agreement. Experiments on hydrogen flow rate also been conducted to obtain the amount of hydrogen consumed to produce electrical work on PEMFC

Neutron cryo-crystallography captures the protonation state of ferryl heme in a peroxidase

Heme enzymes activate oxygen through formation of transient iron-oxo (ferryl) intermediates of the heme iron. A long-standing question has been the nature of the iron-oxygen bond and, in particular, the protonation state. We present neutron structures of the ferric derivative of cytochrome c peroxidase and its ferryl intermediate; these allow direct visualization of protonation states. We demonstrate that the ferryl heme is an Fe(IV)=O species and is not protonated. Comparison of the structures shows that the distal histidine becomes protonated on formation of the ferryl intermediate, which has implications for the understanding of O–O bond cleavage in heme enzymes. The structures highlight the advantages of neutron cryo-crystallography in probing reaction mechanisms and visualizing protonation states in enzyme intermediates

First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters

Publisher's version (útgefin grein)Entanglement in fishing gear is a significant anthropogenic source of large whale injury and mortality. Although entanglements have been reported in the eastern North Atlantic, their frequency has not been previously estimated. This study used systematic scar analysis to estimate the frequency of non-lethal entanglements among individual humpback whales Megaptera novaeangliae off coastal Iceland, from 2005 through 2017. Images of the caudal peduncle and fluke insertions of 379 individuals were analyzed for wrapping injuries and notches known to be indicative of entanglement. The results indicated that at least 24.8% (n = 94, 95% confidence intervals [95% CI]: 20.5-29.1%) of individuals had a history of prior entanglement when first encountered. Depending on the metric used, the whales subsequently acquired new entanglement-related injuries at an average rate of 1.9% (95% CI: 0.6-3.2%) or 16.3% (95% CI: 3.0-29.3%) per year, with no statistically significant change over time. Furthermore, evidence suggests that at least some entanglements occurred locally. Observations of whales with gear still entangling the body confirmed the patterns of injury studied here. These results are lower than scar-based estimates from other parts of the world, but the cause of this difference requires further study. Scar-based methods underestimate the frequency of prior entanglement because some injuries heal beyond recognition, do not involve the caudal peduncle, and may occur on whales that die before they are studied. Long-term monitoring of humpback whale entanglement in Icelandic coastal waters is important for evaluating the local effects of fisheries, as well as the viability of the endangered Cape Verde breeding population.This work was funded in part by a National Geographic Explorer Grant awarded by the National Geographic Society, a PhD sponsorship grant awarded by Gentle Giants Whale Watching, and a Doctoral Grant awarded by Rannís Icelandic Research Fund. We thank all the students at the University of Iceland’s Húsavík Research Center for contributing data, the Faxaflói Ceta - cean Research volunteers (in Húsavík and Reykjavík), and all the whale-watching companies in Iceland who showed interest in the project and contributed photographs and/or space onboard their vessels for data collection. Furthermore, we thank the anonymous reviewers, who provided valuable input into the manuscript. Photographs used in the figures are copyright of University of Iceland (Figs. 2,3,4a1,b,c, 5 & 6a,b,d) Elding Adventures at Sea (Fig. 6c), and Charlie Frank Lavin (Elding Whale Watching Akureyri) (Fig. 4a2).Peer Reviewe

Three applications of path integrals: equilibrium and kinetic isotope effects, and the temperature dependence of the rate constant of the [1,5] sigmatropic hydrogen shift in (Z)-1,3-pentadiene

Recent experiments have confirmed the importance of nuclear quantum effects even in large biomolecules at physiological temperature. Here we describe how the path integral formalism can be used to describe rigorously the nuclear quantum effects on equilibrium and kinetic properties of molecules. Specifically, we explain how path integrals can be employed to evaluate the equilibrium (EIE) and kinetic (KIE) isotope effects, and the temperature dependence of the rate constant. The methodology is applied to the [1,5] sigmatropic hydrogen shift in pentadiene. Both the KIE and the temperature dependence of the rate constant confirm the importance of tunneling and other nuclear quantum effects as well as of the anharmonicity of the potential energy surface. Moreover, previous results on the KIE were improved by using a combination of a high level electronic structure calculation within the harmonic approximation with a path integral anharmonicity correction using a lower level method.Comment: 9 pages, 4 figure

Accuracy of diagnosis and classification of COPD in primary and specialist nurse-led respiratory care in Rotherham, UK : a cross-sectional study

Background: Studies have suggested that chronic obstructive pulmonary disease (COPD) is commonly misdiagnosed and misclassified in primary care, but less is known about the quality of diagnosis in specialist respiratory care. Aims: To measure the accuracy of COPD diagnosis and classification of airway obstruction in primary care and at a specialist respiratory centre, and to explore associations between misdiagnosis and misclassification and a range of explanatory factors. Methods: Data were obtained for 1,205 referrals to a specialist respiratory centre between 2007 and 2010. Standard analysis methods were used. Results: The majority of patients were referred for pulmonary rehabilitation (676/1,205, 56%). Of 1,044 patients with a primary care diagnosis of COPD, 211 (20%) had spirometry inconsistent with COPD. In comparison, of 993 specialist centre diagnoses, 65 (6.5%) had inconsistent spirometry. There was poor agreement between the airflow obstruction grade recorded on the referral and that based on spirometry (kappa=0.26, n=448), whereas agreement between the respiratory centre assessment of airflow obstruction and spirometry was good (kappa=0.88, n=1,016). Referral by practice nurse was associated with accuracy of airflow obstruction classification in primary care (OR 1.85, 95% CI 1.33 to 2.57). Males were more likely than females to have an accurate specialist care classification of airway obstruction (OR 1.40, 95% CI 1.01 to 1.93). Grade of airway obstruction changed between referral and assessment in 56% of cases. Conclusions: In primary care, a proportion of patients diagnosed with COPD do not have COPD, and misclassification of grade of airflow obstruction is common. Misdiagnosis and misclassification is less common in the specialist care setting of BreathingSpace

Characterizing the protein-protein interaction between MDM2 and 14-3-3σ; proof of concept for small molecule stabilization

Mouse Double Minute 2 (MDM2) is a key negative regulator of the tumor suppressor protein p53. MDM2 overexpression occurs in many types of cancer and results in the suppression of WT p53. The 14-3-3 family of adaptor proteins are known to bind MDM2 and the 14-3-3σ isoform controls MDM2 cellular localization and stability to inhibit its activity. Therefore, small molecule stabilization of the 14-3-3σ/MDM2 protein-protein interaction (PPI) is a potential therapeutic strategy for the treatment of cancer. Here, we provide a detailed biophysical and structural characterization of the phosphorylation-dependent interaction between 14-3-3σ and peptides that mimic the 14-3-3 binding motifs within MDM2. The data show that di-phosphorylation of MDM2 at S166 and S186 is essential for high affinity 14-3-3 binding and that the binary complex formed involves one MDM2 di-phosphorylated peptide bound to a dimer of 14-3-3σ. However, the two phosphorylation sites do not simultaneously interact so as to bridge the 14-3-3 dimer in a 'multivalent' fashion. Instead, the two phosphorylated MDM2 motifs 'rock' between the two binding grooves of the dimer, which is unusual in the context of 14-3-3 proteins. In addition, we show that the 14-3-3σ-MDM2 interaction is amenable to small molecule stabilization. The natural product fusicoccin A forms a ternary complex with a 14-3-3σ dimer and an MDM2 di-phosphorylated peptide resulting in the stabilization of the 14-3-3σ/MDM2 PPI. This work serves as a proof-of-concept of the drugability of the 14-3-3/MDM2 PPI and paves the way toward the development of more selective and efficacious small molecule stabilizers.</p

The Mechanism of Substrate Inhibition in Human Indoleamine 2,3-Dioxygenase

Indoleamine 2,3-dioxygenase catalyzes the O(2)-dependent oxidation of L-tryptophan (L-Trp) to N-formylkynurenine (NFK) as part of the kynurenine pathway. Inhibition of enzyme activity at high L-Trp concentrations was first noted more than 30 years ago, but the mechanism of inhibition has not been established. Using a combination of kinetic and reduction potential measurements, we present evidence showing that inhibition of enzyme activity in human indoleamine 2,3-dioxygenase (hIDO) and a number of site-directed variants during turnover with L-tryptophan (L-Trp) can be accounted for by the sequential, ordered binding of O(2) and L-Trp. Analysis of the data shows that at low concentrations of L-Trp, O(2) binds first followed by the binding of L-Trp; at higher concentrations of L-Trp, the order of binding is reversed. In addition, we show that the heme reduction potential (E(m)(0)) has a regulatory role in controlling the overall rate of catalysis (and hence the extent of inhibition) because there is a quantifiable correlation between E(m)(0) (that increases in the presence of L-Trp) and the rate constant for O(2) binding. This means that the initial formation of ferric superoxide (Fe(3+)-O(2)(•-)) from Fe(2+)-O(2) becomes thermodynamically less favorable as substrate binds, and we propose that it is the slowing down of this oxidation step at higher concentrations of substrate that is the origin of the inhibition. In contrast, we show that regeneration of the ferrous enzyme (and formation of NFK) in the final step of the mechanism, which formally requires reduction of the heme, is facilitated by the higher reduction potential in the substrate-bound enzyme and the two constants (k(cat) and E(m)(0)) are shown also to be correlated. Thus, the overall catalytic activity is balanced between the equal and opposite dependencies of the initial and final steps of the mechanism on the heme reduction potential. This tuning of the reduction potential provides a simple mechanism for regulation of the reactivity, which may be used more widely across this family of enzymes