Slider crank wave energy converter performance analysis with adaptive autoregressing filtering

This study investigates a performance analysis of wave excitation force prediction to extract wave power for a slider crank power take-off system (PTOS) based on auto regressive (AR) filters. To efficiently convert wave energy into electricity, the prediction of wave excitation forces into near future to keep the generator and the wave excitation force in sync is important for maximum energy extraction. The study shows a prediction methodology of half period and zero crossings in the practical scenario of irregular ocean waves. The prediction has been tested for different wave periods and with different filter orders in noisy and noiseless environment. The prediction results have been used in the PTOS simulation to analyze the energy extraction. It has been shown that the prediction accuracy in the wave half period between the truth data and the predicted data drives the WEC energy extraction efficiency. The amplitude of the wave force is not used and hence the prediction deviation in the wave force amplitude does not affect the PTOS energy extraction. Further analysis shows that the optimum energy can be extracted at 15th order filter with moderate prediction horizon length

Carbon nanodots in endothelial cells and C57BL/6 mice: a study of toxicity and anti-inflammatory effect

The advancement of therapy for cardiovascular disease (CVD) is paramount to public health, as it is the leading global cause of mortality [1]. Nanomedicine provides new opportunities in the ongoing efforts to reduce the economic and healthcare consequences of CVD. Carbon nanodots (CNDs) green-synthesized from microwave pyrolysis of ethylenediamine and citric acid are spherical, ~3 nm in diameter, and possess exceptional hydrophilic, biocompatible, fluorescent, and anti-oxidant properties. However, there is no current report on how these CNDs affect the cardiovascular system, particularly their potential in mediating endothelial dysfunction and cardiovascular disease (CVD). As a known biomarker of inflammation, Oxidized-LDL (Ox-LDL) induces inflammatory gene expression and monocyte extravasation that leads to atherosclerotic development. This study examines the role of CNDs in mediating Ox-LDL induced inflammation in human microvascular endothelial cells (HMEC-1). Our results demonstrate that CNDs can reduce Ox-LDL induced monocyte adhesion in HMEC-1s, which demonstrates their anti-inflammatory effects. The relative gene expression of the cytokine interleukin-8 (IL-8) was reduced by the addition of CNDs, which implies their action in mediating monocyte recruitment to the site of inflammation. While reactive oxygen species (ROS) perform many essential functions, their overproduction disrupts cellular oxidative balance, induces EC dysfunction, and leads to an inflammatory state. Studying the action of CNDs through Electron paramagnetic resonance (EPR) spectroscopy showed direct superoxide and hydroxyl radical-scavenging by CNDs. This result implies that the anti-inflammatory effects of CNDs seen in vitro are attributed to their direct scavenging of ROS. Furthermore, CNDs were found to ameliorate the cytotoxicity caused by Ox-LDL in HMEC-1s. Viability assays showed CNDs were not cytotoxic at measured concentrations to HMEC-1s in vitro. Animal studies involving mice did not show any morphological or physical changes between the CND and control groups. These collective results demonstrate the potential of CNDs to reduce inflammation and cytotoxicity caused by Ox-LDL in HMEC-1s, which implies their use in the development of novel therapy for cardiovascular disease

Regulation of Myc and its localization to Histone Locus Body in Drosophila

Myc is a transcriptional factor required for normal growth and development in vertebrates and invertebrates alike. Loss of function mutations in Myc can cause embryonic lethality in mammals and larval death in flies whereas an increase in its activity can lead to tumorigenesis. Therefore, proper regulation of Myc is very important to ensure normal development. Regulation of Myc occurs by several context specific mechanisms. One such mechanism is the negative feedback autoregulation of Myc and this mechanism is lost in all tumorigenic cell lines. Like its mammalian homolog, the Drosophila Myc (dMyc) undergoes autoregulation in the presence of an ectopic myc gene leading to a Myc null phenotype. Polycomb (Pc), a chromatin binding repressor is required for Myc autoregulation. Upon Pc knockdown, levels of Su(z)2, a Pc group related protein increase significantly, suggesting that Pc represses Su(z)2. We show here that ectopic Su(z)2 can interfere with Myc autorepression and restore endogenous Myc levels as well as rescue larval lethality caused due to Myc autorepression. Su(z)2 does not however, affect general repression by Myc suggesting that repression of myc locus occurs by a different mechanism. During this study we observed that Myc protein forms distinct puncta in certain tissues. Upon investigating we found that these Myc "spots" localize to sub-nuclear organelles known as Histone Locus Body (HLB). HLBs are histone pre-mRNA processing centers formed at histone gene locus. We show here that Myc localizes to the HLBs only during the S phase. Since hisones are transcribed only during S phase we hypothesize that Myc aids in histone transcription, a novel role for Myc

Inhibition of Cytochrome P450 2E1 and Cytochrome P450 2A6 by essential oils: tarragon (Artemisia dracunculus) and basil (Ocimum basilicum)

Cytochrome P450 enzymes are involved in the metabolism of foreign substances that are present within living organisms. These P450s are classified as Phase I metabolizing enzymes that are found mainly in the liver, they belong to a superfamily of heme containing monoxygenases that are required for metabolism for a number of xenobiotics. Mechanistic approach by these enzymes involves carrying out the oxidation of carbon and nitrogen groups usually resulting in the addition of an alcohol. Cytochrome P450 enzymes have been involved in the bioactivation of inactive compounds to active electrophiles that can contribute to the production of reactive oxygen species, such as superoxide, free radicals, and peroxides. These ROS can contribute to oxidative stress, which leads to hepatic cell necrosis, lipid peroxidation, and DNA adduct formation. This study focuses on two specific Cytochrome P450s, CYP2E1 and CYP2A6. These enzymes have shown to have one of the highest rates of uncoupling among all P450s, this uncoupling leads to the production of ROS. This study focuses on finding potential inhibitors that decrease the chances of these uncoupling reactions from occurring. Human, rat, and rabbit liver microsomes were used for these studies. A series of essential oils were screened with these P450s to determine their inhibitory affects on the enzyme. From these studies, tarragon (Artemisia dracunculus) and basil (Ocimum basilicum) showed the highest inhibitory affects on the enzyme. The major constituent for both these oils was estragole, this was also confirmed via GCMS testing, because of this it was thought that it was a major reason to why the enzyme activity is being inhibited. With the initial screening data showing inhibition of CYP2E1 and CYP2A6, next goal was to determine how potent these oils were and what is the mode of inhibition, reversible or irreversible. The results of CYP2E1 and CYP2A6 with human, rat, and rabbit concluded that both essential oils and estragole inhibited the activity of the enzyme. Estragole was the most potent inhibitor of both enzymes in all 3 species. The KI value for estragole with CYP2E1 in humans was 22.4 µM, in rat 143 µM, and in rabbit 108 µM. The KI value for estragole with CYP2A6 in humans was 27.5 µM and in rabbit was 49.3 µM. Results show that the mode of inhibition shown by both these essential oils and estragole was non-competitive and a reversible type of interaction occurred with both Cytochrome P450 enzymes

ACOUSTIC SIGNAL PROPAGATION CHARACTERIZATION OF CONDUIT NETWORKS

Analysis of acoustic signal propagation in conduit networks has been an important area of research in acoustics. One major aspect of analyzing conduit networks as acoustic channels is that a propagating signal suffers frequency dependent attenuation due to thermo-viscous boundary layer effects and the presence of impedance mismatches such as side branches. The signal attenuation due to side branches is strongly influenced by their numbers and dimensions such as diameter and length. Newly developed applications for condition based monitoring of underground conduit networks involve measurement of acoustic signal attenuation through tests in the field. In many cases the exact installation layout of the field measurement location may not be accessible or actual installation may differ from the documented layout. The lack of exact knowledge of numbers and lengths of side branches, therefore, introduces uncertainty in the measurements of attenuation and contributes to the random variable error between measured results and those predicted from theoretical models. There are other random processes in and around conduit networks in the field that also affect the propagation of an acoustic signal. These random processes include but are not limited to the presence of strong temperature and humidity gradients within the conduits, blockages of variable sizes and types, effects of aging such as cracks, bends, sags and holes, ambient noise variations and presence of variable layer of water. It is reasonable to consider that the random processes contributing to the error in the measured attenuation are independent and arbitrarily distributed. The error, contributed by a large number of independent sources of arbitrary probability distributions, is best described by an approximately normal probability distribution in accordance with the central limit theorem. Using an analytical approach to model the attenuating effect of each of the random variable sources can be very complex and may be intractable. A tractable approach is to develop an empirical model of the attenuation that has a stochastic component of a finite mean and variance to account for the random variable error akin to addition of a normally distributed random variable shadowing component in the path loss models of radio frequency (RF) wireless communication channels. This approach forms the crux of the present study. To develop an empirical model, a large number of measurements in conduit networks were made in the field and in a laboratory test set up to measure the variability of attenuation with variation in four parameters. These parameters include distance of the receiver from the source, frequency, numbers and lengths of side branches. Variation in signal attenuation with distance at each transmitted frequency is predicted by using linear regression through the scatter plot of the measured data. Variations in signal attenuation due to change in frequency, number and lengths of side branches are measured in the field and laboratory tests by comparing the reference transmitted pressure with the received pressure at either the open end or at some distance away from the source along the conduit length. Residuals between measured and predicted sound pressure levels are computed and tested for normal probability distribution through a graphical method as well as a statistical goodness of fit test for quantifiable results. The findings indicate that an empirical model of signal attenuation, which includes a normally distributed random variable component to account for random variable errors in the attenuation measurements, gives a more accurate prediction of received acoustic signal strength in a conduit compared to existing theoretical models

Managerial risk in information technology investments : effects of framing, narrow framing and time inconsistent preferences on real options exercise decisions

Real options theory has been advocated as a solution to risky IT investment decisions. IT investments decisions are risky due to uncertainty around future outcomes and the inability of traditional financial measures (like NPV, IRR) to account for inherent managerial flexibility. On the one hand, it is argued that real options analysis captures and formalizes managers' intuition, hence creating a disciplined decision making process. On the other hand, the intuitive valuation of the options is criticized due to the prevalent effects of various judgmental biases. In this dissertation, we explore three potential biases that can affect the real option exercise decisions in terms of either suboptimal option exercise choice due to framing and narrow framing effects, or suboptimal exercise time due to time inconsistent preferences of IT managers. We test for framing effects in individual IT project decisions and narrow framing effects in IT portfolio decisions, by conducting an online experiment among top and mid-level IT professionals. The results show that IT professionals are prone to framing real options at exercise time and simplifying complicated real option exercise decisions by isolating them in IT portfolios. Further, their decisions are influenced by their personal risk preferences. We analyze the effect of time-inconsistent preferences of present-biased managers on the exercise time of real growth and abandonment options and the realized values using a discrete time option valuation model. The results show that present-biased managers are more likely to exercise growth options early when the net payoffs are low, the growth option payoffs have high volatility, and the risk free discount rate is small. Also, present-biased managers are more likely to exercise abandonment option late when the net payoffs from continuing the project are high, salvage value of the project is low, and the rate of change in the salvage value over the period of time is low. In addition, present biased managers are more likely to exercise a growth option early in its life when the project is performing well. We provide implications for practice and IT governance

Oralne manifestacije u pedijatrijskih bolesnika zaraženih virusom humane imunodefi cijencije na antiretrovirusnoj terapiji i bez nje: presječno istraživanje

The aim of the study was to assess and compare oral manifestations of human immunodefi ciency virus (HIV) infected pediatric patients undergoing antiretroviral therapy (ART) and those not undergoing ART. A cross sectional study included HIV positive children (receiving and not receiving ART) aged 5-15 years, registered at the District Hospital ART Centre, Udaipur, and HIV negative schoolchildren. HIV related oral lesions were diagnosed according to the World Health Organization criteria. Sociodemographic and other related information were also recorded. CD4+ cell count was determined in all study subjects. The χ2 -test, stepwise multiple linear regression and logistic regression were used on statistical analysis. In all tests, confi dence interval and p-value were set at 95% and ≤0.05, respectively. A greater proportion of HIV patients receiving treatment had CD4+ cell count of more than 750 cells/mm3 . The majority of HIV patients receiving ART for more than three years and only 20% of those not receiving ART were free from any oral lesions. The results of the present study demonstrated ART to be eff ective in reducing the prevalence of HIV related oral lesions, as already described in the literature; however, unlike previous studies, the present paper reports more valid fi ndings for having included most of the confounding variablesCilj istraživanja bio je procijeniti i usporediti oralne manifestacije u pedijatrijskih bolesnika zaraženih virusom humane imunodefi - cijencije (HIV) koji primaju antiretrovirusnu terapiju (ART) i onih koji ne primaju ovu terapiju. Ovo presječno istraživanje uključilo je HIV pozitivnu djecu (djecu koja primaju ART i djecu koja ne primaju ART) u dobi od 5-15 godina, registriranu pri Centru za ART u Pokrajinskoj bolnici u Udaipuru te HIV negativnu školsku djecu. Oralne promjene povezane s HIV-om dijagnosticirane su prema kriterijima Svjetske zdravstvene organizacije. Prikupljeni su socio-demografski te ostali podaci za svu djecu uključenu u ispitivanje. U svih je određen broj CD4+ stanica. U statističkoj analizi primijenjen je χ2 -test te postupna višestruka linearna regresija i logistička regresija. U svim testovima interval vjerodostojnosti i vrijednost p utvrđeni su na razini od 95% odnosno ≤0,05. Broj CD4+ stanica veći od 750 stanica/mm3 zabilježen je u većem postotku HIV bolesnika na ART. Bez oralnih promjena bila je većina HIV bolesnika koji su primali ART duže od tri godine, ali samo 20% onih koji nisu primali ART. Rezultati ovoga istraživanja pokazuju da ART učinkovito snižava učestalost oralnih promjena povezanih s HIV-om, što je već prije opisano u literaturi. Međutim, za razliku od prijašnjih ispitivanja, nalazi prikazani u ovom radu imaju veću vrijednost, jer uključuju većinu čimbenika koji bi mogli utjecati na rezultate

Postpartum spontaneous dissection of the first obtuse marginal branch of the left circumflex coronary artery causing acute coronary syndrome: a case report and literature review

Spontaneous coronary artery dissection (SCAD) is a very rare cause of acute coronary syndromes in young otherwise healthy patients with a striking predilection for the female gender. The pathological mechanism has not been fully clarified yet. However, several diseases and conditions have been associated with SCAD, such as atherosclerosis, connective tissue disorders and the peripartum episode. In this paper we present a review of the literature, discussing the possible mechanisms for SCAD, therapeutic options and prognosis. The review is illustrated with two SCAD patients who had a recurrence of a spontaneous dissection in another artery within a few days after the initial event. Because of the susceptibility to recurrent spontaneous dissections we propose at least one week of observation in hospital. Further, we will elaborate on the possible conservative and invasive treatment strategies in the acute phase of SCAD. Primary percutaneous coronary intervention remains the reperfusion strategy of choice; however, in small and medium-sized arteries with normalised flow conservative treatment is defendable. In addition, after the acute phase evaluation of possible underlying diseases is necessary, because it affects further treatment. (Neth Heart J 2008;16:344-9.

Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHA–PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA–PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules

Protonation of the oxo-bridged heme/copper assemblies: Modeling the oxidized state of the cytochrome c oxidase active site

In this study on model compounds for the resting oxidized state of the iron copper binuclear center in cytochrome c oxidase (CcO), we describe the synthesis of a new µ-oxo-heme/Cu complex, [(TPP)FeIII–O–CuII(tmpa)][B(C6F5)4] (2) {TPP: tetraphenyl porphyrinate(2–); TMPA: tris(2-pyridylmethylamine)}, as well as two protonation events for three µ-oxo-heme/Cu complexes with varying peripheral substituents on the heme site. The addition of increasing amounts of strong acid to these µ-oxo-heme/Cu systems successively led to the generation of the corresponding µ-hydroxo, µ-aquo, and the dissociated complexes. The heme/Cu assemblies bridged through a water ligand are reported here for the first time and the 1H NMR and 19F NMR spectral properties are consistent with antiferromagnetically coupled high-spin iron(III) and copper(II) centers. By titration using a series of protonated amines, the pKa values for the corresponding µ-hydroxo-heme/Cu species (i.e., the first protonation event) have been reported and compared with the pKa ranges previously estimated for related systems. These synthetic systems may represent structural models for the oxidized FeIII–X–CuII resting state, or turnover intermediates and can be employed to clarify the nature of proton/electron transfer events in CcO. Synopsis: The resting oxidized state of the cytochrome c oxidase active site contains an Fea3-OHx-CuB moiety. Here, we investigated two successive protonation events, for a series of µ-oxo-heme/Cu assemblies and reported the pKa values for the first protonation event. The µ-aquo-heme/Cu complexes described here are the first examples of such systems