Detritus type alters the outcome of interspecific competition between Aedes aegypti and Aedes albopictus (Diptera : Culicidae)

Many studies of interspecific competition between Aedes albopictus (Skuse) and Aedes aegypti (L.) (Diptera: Culicidae) larvae show that Ae. albopictus are superior resource competitors to Ae. aegypti. Single-species studies indicate that growth and survival of Ae. albopictus and Ae. aegypti larvae are affected by the type of detritus present in containers, which presumably affects the amount and quality of microorganisms that the mosquito larvae consume. We tested whether different detritus types alter the intensity of larval competition by raising 10 different density/species combinations of Ae. albopictus and Ae. aegypti larvae under standard laboratory conditions, with one of four detritus types (oak, pine, grass, or insect) provided as a nutrient base. Intraspecific competitive effects on survival were present with all detritus types. Ae. albopictus survivorship was unaffected by interspecific competition in all treatments. Negative interspecific effects on Ae. aegypti survivorship were present with three of four detritus types, but absent with grass. Estimated finite rate of increase (lambda\u27) was lower with pine detritus than with any other detritus type for both species. Furthermore, Ae. aegypti lambda\u27 was negatively affected by high interspecific density in all detritus types except grass. Thus, our experiment confirms competitive asymmetry in favor of Ae. albopictus with oak, pine, or insect detritus, but also demonstrates that certain detritus types may eliminate interspecific competition among the larvae of these species, which may allow for stable coexistence. Such variation in competitive outcome with detritus type may help to account for observed patterns of coexistence/exclusion of Ae. albopictus and Ae. aegypti in the field

Kinematic control design for wheeled mobile robots with longitudinal and lateral slip

The motion control of wheeled mobile robots at high speeds under adverse ground conditions is a difficult task, since the robots' wheels may be subject to different kinds of slip. This work introduces an adaptive kinematic controller that is capable of solving the trajectory tracking problem of a nonholonomic mobile robot under longitudinal and lateral slip. While the controller can effectively compensate for the longitudinal slip, the lateral slip is a more involved problem to deal with, since nonholonomic robots cannot directly produce movement in the lateral direction. To show that the proposed controller is still able to make the mobile robot follow a reference trajectory under lateral and longitudinal time-varying slip, the solutions of the robot's position and orientation error dynamics are shown to be uniformly ultimately bounded. Numerical simulations are presented to illustrate the robot's performance using the proposed adaptive control law

Cysteine 904 is required for maximal insulin degrading enzyme activity and polyanion activation

Cysteine residues in insulin degrading enzyme have been reported as non-critical for its activity. We found that converting the twelve cysteine residues in rat insulin degrading enzyme (IDE) to serines resulted in a cysteine-free form of the enzyme with reduced activity and decreased activation by polyanions. Mutation of each cysteine residue individually revealed cysteine 904 as the key residue required for maximal activity and polyanion activation, although other cysteines affect polyanion binding to a lesser extent. Based on the structure of IDE, Asn 575 was identified as a potential hydrogen bond partner for Cys904 and mutation of this residue also reduced activity and decreased polyanion activation. The oligomerization state of IDE did not correlate with its activity, with the dimer being the predominant form in all the samples examined. These data suggest that there are several conformational states of the dimer that affect activity and polyanion activation

Specific fluorogenic substrates for neprilysin (neutral endopeptidase, EC 3.4.24.11) which are highly resistant to serine- and metalloproteases

Two intramolecularly quenched fluorogenic peptides containing o-aminobenzoyl (Abz) and ethylenediamine 2,4-dinitrophenyl (EDDnp) groups at amino- and carboxyl-terminal amino acid residues, Abz-DArg-Arg-Leu-EDDnp (Abz-DRRL-EDDnp) and Abz-DArg-Arg-Phe-EDDnp (Abz-DRRF-EDDnp), were selectively hydrolyzed by neutral endopeptidase (NEP, enkephalinase, neprilysin, EC 3.4.24.11) at the Arg-Leu and Arg-Phe bonds, respectively. The kinetic parameters for the NEP-catalyzed hydrolysis of Abz-DRRL-EDDnp and Abz-DRRF-EDDnp were Km = 2.8 µM, kcat = 5.3 min-1, kcat/Km = 2 min-1 µM-1 and Km = 5.0 µM, kcat = 7.0 min-1, kcat/Km = 1.4 min-1 µM-1, respectively. The high specificity of these substrates was demonstrated by their resistance to hydrolysis by metalloproteases [thermolysin (EC 3.4.24.2), angiotensin-converting enzyme (ACE; EC 3.4.24.15)], serineproteases [trypsin (EC 3.4.21.4), a-chymotrypsin (EC 3.4.21.1)] and proteases present in tissue homogenates from kidney, lung, brain and testis. The blocked amino- and carboxyl-terminal amino acids protected these substrates against the action of aminopeptidases, carboxypeptidases and ACE. Furthermore, DR amino acids ensured total protection of Abz-DRRL-EDDnp and Abz-DRRF-EDDnp against the action of thermolysin and trypsin. Leu-EDDnp and Phe-EDDnp were resistant to hydrolysis by a-chymotrypsin. The high specifity of these substrates suggests their use for specific NEP assays in crude enzyme preparationsUniversidade Federal do CearáUniversité de MontréalUniversidade Federal de São Paulo (UNIFESP)UNIFESPSciEL

Kernel Interpolation of Incident Sound Field in Region Including Scattering Objects

A method for estimating the incident sound field inside a region containing scattering objects is proposed. The sound field estimation method has various applications, such as spatial audio capturing and spatial active noise control; however, most existing methods do not take into account the presence of scatterers within the target estimation region. Although several techniques exist that employ knowledge or measurements of the properties of the scattering objects, it is usually difficult to obtain them precisely in advance, and their properties may change during the estimation process. Our proposed method is based on the kernel ridge regression of the incident field, with a separation from the scattering field represented by a spherical wave function expansion, thus eliminating the need for prior modeling or measurements of the scatterers. Moreover, we introduce a weighting matrix to induce smoothness of the scattering field in the angular direction, which alleviates the effect of the truncation order of the expansion coefficients on the estimation accuracy. Experimental results indicate that the proposed method achieves a higher level of estimation accuracy than the kernel ridge regression without separation.Comment: Accepted to IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA) 202

Characterization of thimet oligopeptidase and neurolysin activities in B16F10-Nex2 tumor cells and their involvement in angiogenesis and tumor growth

<p>Abstract</p> <p>Background</p> <p>Angiogenesis is a fundamental process that allows tumor growth by providing nutrients and oxygen to the tumor cells. Beyond the oxygen diffusion limit from a capillary blood vessel, tumor cells become apoptotic. Angiogenesis results from a balance of pro- and anti-angiogenic stimuli. Endogenous inhibitors regulate enzyme activities that promote angiogenesis. Tumor cells may express pro-angiogenic factors and hydrolytic enzymes but also kinin-degrading oligopeptidases which have been investigated.</p> <p>Results</p> <p>Angiogenesis induced by B16F10-Nex2 melanoma cells was studied in a co-culture with HUVEC on Matrigel. A stimulating effect on angiogenesis was observed in the presence of B16F10-Nex2 lysate and plasma membrane. In contrast, the B16F10-Nex2 culture supernatant inhibited angiogenesis in a dose-dependent manner. This effect was abolished by the endo-oligopeptidase inhibitor, JA-2. Thimet oligopeptidase (TOP) and neurolysin activities were then investigated in B16F10-Nex2 melanoma cells aiming at gene sequencing, enzyme distribution and activity, influence on tumor development, substrate specificity, hydrolytic products and susceptibility to inhibitors. Fluorescence resonance energy transfer (FRET) peptides as well as neurotensin and bradykinin were used as substrates. The hydrolytic activities in B16F10-Nex2 culture supernatant were totally inhibited by <it>o</it>-phenanthrolin, JA-2 and partially by Pro-Ile. Leupeptin, PMSF, E-64, Z-Pro-Prolinal and captopril failed to inhibit these hydrolytic activities. Genes encoding M3A enzymes in melanoma cells were cloned and sequenced being highly similar to mouse genes. A decreased proliferation of B16F10-Nex2 cells was observed in vitro with specific inhibitors of these oligopeptidases. Active rTOP but not the inactive protein inhibited melanoma cell development in vivo increasing significantly the survival of mice challenged with the tumor cells. On Matrigel, rTOP inhibited the bradykinin – induced angiogenesis. A possible regulation of the homologous tumor enzyme in the perivascular microenvironment is suggested based on the observed rTOP inhibition by an S-nitrosothiol NO donor.</p> <p>Conclusion</p> <p>Data show that melanoma cells secrete endo-oligopeptidases which have an important role in tumor proliferation in vitro and in vivo. rTOP inhibited growth of subcutaneously injected B16F10-Nex2 cells in mice. TOP from tumor cells and bradykinin in endothelial cells are two antagonist factors that may control angiogenesis essential for melanoma growth. A regulatory role of NO or S-nitrosothiols is suggested.</p

A Methodology to Predict the Remaining Service Life of CSCPs

Despite the fact that corrugated steel culvert pipe (CSCP) is widely used for stream crossings and drainage in many transportation systems in the US, historically, very little has been done regarding its condition assessment and planned maintenance. This research provides a methodology for developing a comprehensive plan for inspection, cleaning, condition assessment and prediction of remaining service of CSCP. Inspection frequency guidelines were developed based upon culvert size, age, importance and environmental factors, e.g., corrosion and erosion, bed load and pH. The CSCPs are classified into three levels according to increasing need for inspection, e.g., annual inspections are recommended for Level III. A four Condition State assessment system was developed based upon the CalTrans system, which includes quantifiable section losses, specific surface features, and a prescribed response associated with each condition state. A Markov deterioration model was used to predict the future Condition States and the probability of failure of new CSCP over a 30-year life for both urban and rural settings. The transition probabilities were based upon inspection data and corrosion case studies. The probability of failure ranged from 25 to 65 percent for the rural and urban areas respectively. Improvements to the model that will take into account the effects of maintenance and rehabilitation will be addressed in the next phase of the research project

A Methodology to Predict the Remaining Service Life of CSCPs

Despite the fact that corrugated steel culvert pipe (CSCP) is widely used for stream crossings and drainage in many transportation systems in the US, historically, very little has been done regarding its condition assessment and planned maintenance. This research provides a methodology for developing a comprehensive plan for inspection, cleaning, condition assessment and prediction of remaining service of CSCP. Inspection frequency guidelines were developed based upon culvert size, age, importance and environmental factors, e.g., corrosion and erosion, bed load and pH. The CSCPs are classified into three levels according to increasing need for inspection, e.g., annual inspections are recommended for Level III. A four Condition State assessment system was developed based upon the CalTrans system, which includes quantifiable section losses, specific surface features, and a prescribed response associated with each condition state. A Markov deterioration model was used to predict the future Condition States and the probability of failure of new CSCP over a 30-year life for both urban and rural settings. The transition probabilities were based upon inspection data and corrosion case studies. The probability of failure ranged from 25 to 65 percent for the rural and urban areas respectively. Improvements to the model that will take into account the effects of maintenance and rehabilitation will be addressed in the next phase of the research project