Model Identification of a Micro Air Vehicle

This paper is focused on the model identification of a Micro Air Vehicle （MAV） in straight steady flight condition. The identification is based on input-output data collected from flight tests using both frequency and time dorrtain techniques. The vehicle is an in-house 40 cm wingspan airplane. Because of the complex coupled, multivariable and nonlinear dynamics of the aircraft, linear SISO structures for both the lateral and longitudinal models around a reference state were derived. The aim of the identification is to provide models that can be used in future development of control techniques for the MAV.     

Platelet-derived growth factor stimulates phospholipase C-gamma 1, extracellular signal-regulated kinase, and arachidonic acid release in rat myometrial cells: contribution to cyclic 3',5'-adenosine monophosphate production and effect on cell proliferation

In the present study, we examined downstream signaling events that followed exposure of cultured rat myometrial cells to platelet-derived growth factor (PDGF) and their effect on cell proliferation. PDGF-BB induced tyrosine phosphorylation of PDGF-beta receptors and increased inositol trisphosphate production via the tyrosine phosphorylation of phospholipase (PL)C-gamma 1. PDGF-BB also increased cAMP synthesis. This increase was potentiated by forskolin and reduced by indomethacin, a cyclooxygenase inhibitor, reflecting a Gs protein-mediated process via prostaglandin biosynthesis. The prostaglandin produced by PDGF was characterized as prostacyclin (PGI(2)). PDGF-BB increased arachidonic acid (AA) release, which, similarly to cAMP accumulation, was abolished in the presence of AACOCF3, a cytosolic PLA(2) inhibitor, and in the absence of Ca(2+). U-73122, a potent inhibitor of PLC activity, blocked both the production of inositol phosphates and the AA release triggered by PDGF-BB. Extracellular signal-regulated kinases (ERKs) 1 and 2 are expressed in myometrial cells, and PDGF-BB selectively activated ERK2. PD98059, an inhibitor of the ERK-activating kinase, blocked PDGF-BB-mediated ERK2 activation, AA release, and cAMP production. The results demonstrate that PDGF-BB stimulated cAMP formation through both PLC activation and ERK-dependent AA release and PGI(2) biosynthesis. PDGF-BB also increased cell proliferation and [(3)H]thymidine incorporation. This was abolished by PD98059, demonstrating that the ERK cascade is required for the mitogenic effect of PDGF-BB. Forskolin, which potentiated the cAMP response to PDGF-BB, attenuated both DNA synthesis and ERK activation triggered by PDGF-BB, suggesting the presence of a negative feedback regulation.     

A model for thermograms

Thermograms are curves resulting from thermal analysis and are of great interest in the study of various food and biological products physical properties. A method to separate underlying peaks is proposed, and statistical properties of estimates for some characteristic parameters are derived. The total number of peaks can be estimated with a sequential analysis of the residual plots. For each new peak, a statistical criterion is proposed to check whether it is significantly different from the noise of the recording. As an example, the method is applied to a summer milk fat fusion thermogram.     

Modelling nitrate influx in young tomato (Lycopersicon esculentum Mill.) plants

The effects of light and NO3^- nutrition on ¹⁵NO3^- influx in roots were investigated in young, 19-d-old, induced tomato plants grown at a constant air and solution temperature of 20C. Nitrate influx was measured by ¹⁵N accumulation for 5 min, on plants exposed to a wide range of exogenous concentrations, from 10 x 10^-3 to 30 mol m^-3. Influx kinetics, fitted to the data following a non-linear procedure, showed multiphasic patterns. The best fits were obtained when three pure and non-additive Michaelis-Menten kinetics were applied, with phase transitions at approximately 0.8 and 4 mol m^-3. In plants grown at 3.0 mol m^-3 NO3^-, the asymptotic maximum influx rate (Imax) of each phase declined during the night until 24 h darkness. At the end of the day period, about a 2-fold enhancement of Imax was observed when plants were pretreated for 3 d with 0.2 instead of 3.0 mol m^-3 NO3^-. The influx rates measured at any given NO3^- concentration and the Imax for any phase showed a negative non-linear correlation with plant nitrate concentration. Furthermore, the results suggest the existence of a set point, approximately 66 mol m^-3 plant nitrate, for which influx is null at any given solution nitrate concentration. A model using modified Michaelis-Menten kinetics is proposed to predict the influx rate as a function of both solution and plant NO3^- concentrations.     

Relationship in humans between spontaneously chosen crank rate and power output during upper body exercise at different levels of intensity

The aim of this study was to assess the relationship between spontaneously chosen crank rate (SCCR) and power output during two upper body exercise tests: firstly, an incremental maximal aerobic power test (T1), with an initial intensity of 50 W followed by 15-W increases at each subsequent 90-s stage and secondly, a test (T2) with consecutive exercise periods set at 50%, 60%, 70%, 80%, 110% and 120% of maximal power (Pmax) separated by passive recovery periods. Eight nationally and internationally ranked kayakers, aged 20 (SD 2) years, performed the tests. During both T1 and T2, mean SCCR values were correlated (r = 1) and increased significantly (P < 0.05) in association with the increases in power output. The finding that the subjects consistently increased their crank rate as the power output increased in different tests, i.e. at submaximal, maximal and supramaximal intensities, strongly suggests that SCCR depended on power output and not on the type of exercise (incremental or rectangular exercise). Moreover, the equation relating crank rate and power output determined from T1 suggests that it may be used to predict the crank rate which will be chosen in upper body exercise, whatever the intensity. Finally, the results of testing at 110% and 120% of Pmax would suggest that a high crank rate (>90 rpm) should be used during the test procedure using supramaximal exercises where accumulated oxygen deficit is calculated, and more particularly when exercise is performed using the upper body.     

Functional analysis of two-amino acid substitutions in gp91<Emphasis Type="Italic">phox</Emphasis> in a patient with X-linked flavocytochrome <Emphasis Type="Italic">b</Emphasis><Subscript>558</Subscript>-positive chronic granulomatous disease by means of transgenic PLB-985 cells

Chronic granulomatous disease (CGD) is a rare inherited disorder in which phagocytes lack NADPH oxidase activity. The most common form is caused by mutations in the CYBB gene encoding gp91phox protein, the heavy chain of cytochrome b₅₅₈, which is the redox element of NADPH oxidase. In some rare cases, the mutated gp91phox is normally expressed but no NADPH oxidase can be detected. This type of CGD is called X91⁺ CGD. We have previously reported an X⁺ CGD case with a double-missense mutation in gp91phox. Transgenic PLB-985 cells have now been made to study the impact of each single mutation on oxidase activity and assembly to rule out a possible new polymorphism in the CYBB gene. The His303Asn/Pro304Arg gp91phox transgenic PLB-985 cells exactly mimic the phenotype of the neutrophils of the X⁺ CGD patient. The His303Asn mutation is sufficient to inhibit oxidase activity in intact cells and in a broken cell system, whereas in the Pro304Arg mutant, residual activity suggests that the Pro304Arg substitution is less devastating to oxidase activity than the His303Asn mutation. The study of NADPH oxidase assembly following the in vitro and in vivo translocation of cytosolic factors p47phox and p67phox has demonstrated that, in the double mutant and in the His303Asn mutant, NADPH oxidase assembly is abolished, although the translocation is only attenuated in Pro304Arg mutant cells. Thus, even though the His303Asn mutation has a more severe inhibitory effect on NADPH oxidase activity and assembly than the Pro304Arg mutation, neither mutation can be considered as a polymorphism.Clara Bionda and Xing Jun Li contributed equally to this work     

Saturation transfer difference (STD) 1H-NMR experiments and in silico docking experiments to probe the binding of N-acetylneuraminic acid and derivatives to Vibrio cholerae sialidase

Saturation transfer difference (STD) (1)H NMR experiments were used to probe the epitope binding characteristics of the sialidase [EC 3.2.1.18] from the bacterium Vibrio cholerae, the causative agent of cholera. Binding preferences were investigated for N-acetylneuraminic acid (Neu5Ac, 1), the product of the sialidase catalytic reaction, for the known sialidase inhibitor 5-acetamido-2,6-anhydro-3,5-dideoxy-D-glycero-D-galacto-non-2-enoic acid (Neu5Ac2en, 2), and for the uronic acid-based Neu5Ac2en mimetic iso-propyl 2-acetamido-2,4-dideoxy-alpha-L-threo-hex-4-enopyranosiduronic acid (3), in which the native glycerol side-chain of Neu5Ac2en is replaced with an O-iso-propyl ether. The STD experiments provided evidence, supporting previous studies, that Neu5Ac (1) binds to the sialidase as the alpha-anomer. Docking experiments using DOCK (version 4.0.1) revealed further information regarding the binding characteristics of the enzyme active site in complex with Neu5Ac2en (2) and the Neu5Ac2en mimetic (3), indicating an expected dominant interaction of the acetamide moiety with the protein.