19-Azasqualene-2,3-epoxide and its N-oxide: Metabolic fate and inhibitory effect on sterol biosynthesis in Saccharomyces cerevisiae

19-Azasqualene-2,3-epoxide was more inhibitory than the corresponding N-oxide against 2,3-oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC₅₀ 7±2 and 25±5 μM, respectively). Both compounds showed a reversible, noncompetitive-type inhibition on solubilized OSC. Different inhibitory properties between the compounds were especially evident when measuring [¹⁴C]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19-azasqualene-2,3-epoxide at 30 μM, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over 40% of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N-oxide derivative under the same conditions. 19-Azasqualene-2,3-epoxide was also more effective than the N-oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 μM, respectively). The two inhibitors underwent different metabolic fates in the yeast: while 19-azasqualene-2,3-epoxide did not undergo any transformation, its N-oxide was actively reduced to the corresponding amine in whole and in “ultrasonically stimulated” cells. The N-oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic fates is discussed.     

Role of Crystallographic Textures on Failure Behavior in HSLA Grade-420 Steel During Cold Rolling

The microstructural and textural evolution was analyzed during rolling at room temperature to obtain detailed information about the failure behavior in HSLA grade-420 steel. Electron backscatter diffraction measurements were carried out in both non-cracked and cracked areas after cold rolling to find a correlation between microstructural parameters (i.e., grain orientation, grain boundary characteristics and Taylor factor) and crack propagation. The results showed that the crack tended to propagate along grains oriented with {001} planes parallel to the normal direction with high Taylor factor value. The special boundaries associated with the {111}, {110} and {221} planes were indicated as crack resistance, while ∑ 5, 13a and 17a, which related to the {001} planes, were crack-susceptible. Transgranular cracking was subjected within grains with high Taylor factor, while mismatch in Taylor factor between neighboring grains could provide an easy path for intergranular crack propagation.     

The Age-Sensitive Efficacy of Calorie Restriction on Mitochondrial Biogenesis and mtDNA Damage in Rat Liver

Calorie restriction (CR) is the most efficacious treatment to delay the onset of age-related changes such as mitochondrial dysfunction. However, the sensitivity of mitochondrial markers to CR and the age-related boundaries of CR efficacy are not fully elucidated. We used liver samples from ad libitum-fed (AL) rats divided in: 18-month-old (AL-18), 28-month-old (AL-28), and 32-month-old (AL-32) groups, and from CR-treated (CR) 28-month-old (CR-28) and 32-month-old (CR-32) counterparts to assay the effect of CR on several mitochondrial markers. The age-related decreases in citrate synthase activity, in TFAM, MFN2, and DRP1 protein amounts and in the mtDNA content in the AL-28 group were prevented in CR-28 counterparts. Accordingly, CR reduced oxidative mtDNA damage assessed through the incidence of oxidized purines at specific mtDNA regions in CR-28 animals. These findings support the anti-aging effect of CR up to 28 months. Conversely, the protein amounts of LonP1, Cyt c, OGG1, and APE1 and the 4.8 Kb mtDNA deletion content were not affected in CR-28 rats. The absence of significant differences between the AL-32 values and the CR-32 counterparts suggests an age-related boundary of CR efficacy at this age. However, this only partially curtails the CR benefits in counteracting the generalized aging decline and the related mitochondrial involvement.     

Nanostructured hematite thin films produced by spin-coating deposition solution: Application in water splitting

Doped and undoped hematite films for photoelectrochemical hydrogen production were prepared by spin-coating deposition solution (SCDS). To understand the influence of the Si-doping and identify the critical parameters of the proposed SCDS method an extensive characterization was conducted. The Si-doped hematite exhibited higher photocurrent response when compared with undoped films. We have shown that the crystallographic orientation degree of the films appears to be a dominant factor affecting the photocurrent. The performance of our hematite electrodes is well below the maximum theoretical efficiency and the conceivable explanation could be given by the high value of recombination phenomena (electron/hole pair).     

EXPERIMENTAL IMPLEMENTATION OF AN ARTIFICIAL IMMUNE SYSTEM ON A ROBOTIC MANIPULATOR

An artificial immune system (AIS) has been used to realize robust control of a robotic manipulator. The AIS recognizes “self” and “non-self” operation of a closed-loop system, where self is defined as a condition where controller gains are appropriate for a given manipulator configuration. As configuration changes occur, the changing performance of the system indicates a transition to non-self. When non-self operation is first detected, the corresponding dynamic response is defined as a receptor and a genetic algorithm (GA) is called to optimize the controller for the new configuration. A library of receptors is built as additional configuration changes are experienced. For subsequent self to non-self transitions, new and recorded receptors are compared. In the event of a high correlation between the receptors, previously determined controller gains are implemented without calling the GA. The system is agile and robust and can recognize and respond to recognized receptors within a single reference step.     

Observations of wind and ocean wave fields using ERS Synthetic Aperture Radar imagery

The aim of the research reported here is to evaluate Synthetic Aperture Radar (SAR) capability to estimate the wind vector and associated directional wave spectrum. Two ERS–2 SAR images of the Mediterranean Sea, one over the Sicily Channel and one over the Ligurian Sea, were selected as case studies. Wind speed was estimated using SAR calibrated backscatter response, in conjunction with empirically derived ERS scatterometer models such as CMOD4 and CMOD–IFREMER. The predictions of these models were then compared with the actual sea surface wave spectra either provided by in situ measurements or resulting from the inversion of the SAR image spectrum. SAR-detected effects of both wind and wave features, induced either by atmospheric boundary layer instability or by land shadowing, were also used as reliable indicators of wind direction.     

Verification of cardiac tissue electrophysiology simulators using an N-version benchmark

Ongoing developments in cardiac modelling have resulted, in particular, in the development of advanced and increasingly complex computational frameworks for simulating cardiac tissue electrophysiology. The goal of these simulations is often to represent the detailed physiology and pathologies of the heart using codes that exploit the computational potential of high-performance computing architectures. These developments have rapidly progressed the simulation capacity of cardiac virtual physiological human style models; however, they have also made it increasingly challenging to verify that a given code provides a faithful representation of the purported governing equations and corresponding solution techniques. This study provides the first cardiac tissue electrophysiology simulation benchmark to allow these codes to be verified. The benchmark was successfully evaluated on 11 simulation platforms to generate a consensus gold-standard converged solution. The benchmark definition in combination with the gold-standard solution can now be used to verify new simulation codes and numerical methods in the future.     

Onion under Microscope: An in-depth analysis of the Tor Web

World Wide Web - Tor is an open source software that allows accessing various kinds of resources, known as hidden services, while guaranteeing sender and receiver anonymity. Tor relies on a free,...     

Two-space variability compensation technique for speaker verification in short length and reverberant environments

The performance of state-of-the-art speaker verification in uncontrolled environment is affected by different variabilities. Short duration variability is very common in these scenarios and causes the speaker verification performance to decrease quickly while the duration of verification utterances decreases. Linear discriminant analysis (LDA) is the most common session variability compensation algorithm, nevertheless it presents some shortcomings when trained with insufficient data. In this paper we introduce two methods for session variability compensation to deal with short-length utterances on i-vector space. The first method proposes to incorporate the short duration variability information in the within-class variance estimation process. The second proposes to compensate the session and short duration variabilities in two different spaces with LDA algorithms (2S-LDA). First, we analyzed the behavior of the within and between class scatters in the first proposed method. Then, both proposed methods are evaluated on telephone session from NIST SRE-08 for different duration of the evaluation utterances: full (average 2.5 min), 20, 15, 10 and 5 s. The 2S-LDA method obtains good results on different short-length utterances conditions in the evaluations, with a EER relative average improvement of 1.58%, compared to the best baseline (WCCN[LDA]). Finally, we applied the 2S-LDA method in speaker verification under reverberant environment, using different reverberant conditions from Reverb challenge 2013, obtaining an improvement of 8.96 and 23% under matched and mismatched reverberant conditions, respectively.