Collaborative Localization for Multi-Robot System with Fault Detection and Exclusion Based on the Kullback-Leibler Divergence

Multi-robot system attracted attention in various applications in order to replace the human operators. To achieve the intended goal, one of the main challenges of this system is to ensure the integrity of localization by adding a sensor fault diagnosis step to the localization task. In this paper, we present a framework able, in addition of localizing a group of robots, to detect and exclude the faulty sensors from the group with an optimized thresholding method. The estimator has the informational form of the Kalman Filter (KF) namely Information Filter (IF). A residual test based on the Kullback-Leibler divergence (KLD) between the predicted and the corrected distributions of the IF is developed. It is generated from two tests: the first acts on the means and the second deals with the covariance matrices. Thresholding using entropy based criterion and Receiver Operating Characteristics (ROC) curve are discussed. Finally, the validation of this framework is studied on real experimental data from a group of robots.     

Effect of polyaniline–montmorillonite nanocomposite powders addition on corrosion performance of epoxy coatings on Al 5000

A series of polyaniline (PANI)/montmorillonite (MMT) nanocomposite materials has been successfully prepared by in-situ emulsion polymerization in the presence of inorganic nanolayers of clay with camphorsulfonic acid (CSA) and ammonium peroxydisulfate (APS) as surfactant and initiator, respectively. The nanocomposite materials were characterized by Fourier Transformation Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Epoxy resin was used as a binder for the nanocomposites in order to obtain a thick and uniform coating. In order to understand the effect of MMT and PANI on the corrosion inhibition performance of the epoxy coatings in 3.5% saline solution at 65 °C, the epoxy (E), epoxy blend with polyaniline (EP), epoxy blend with polyaniline and MMT (EPM) coatings were investigated by electrochemical impedance spectroscopy (EIS). The results showed that EPM coatings with 5% clay on pretreated aluminum by anodizing were much superior in corrosion protection, with respect to the other samples. Incorporation of PACN nanocomposites inside the epoxy significantly increases the resistance of the coating in comparison to the other coatings in 3.5% saline solution at 65 °C. These phenomena can be attributed to specific morphology of the nanocomposite.     

Shear Strength of Fiber-Reinforced Sands

Soil reinforcement using discrete randomly distributed fibers has been widely investigated over the last 30 years. Several models were suggested to estimate the improvement brought by fibers to the shear strength of soils. The objectives of this paper are to (1) supplement the data available in the literature on the behavior of fiber-reinforced sands; (2) study the effect of several parameters which are known to affect the shear strength of fiber-reinforced sands; and (3) investigate the effectiveness of current models in predicting the improvement in shear strength of fiber-reinforced sand. An extensive direct shear testing program was implemented using coarse and fine sands tested with three types of fibers. Results indicate the existence of a fiber-grain scale effect which is not catered for in current prediction models. A comparison between measured and predicted shear strengths indicates that the energy dissipation model is effective in predicting the shear strength of fiber-reinforced specimens in reference to the tests conducted in this study. On the other hand, the effectiveness of the predictions of the discrete model is affected by the parameters of the model, which may depend on the test setup and the procedure used for mixing the fibers.     

Tyrosine-dependent and -independent mechanisms of STAT3 activation by the human granulocyte colony-stimulating factor (G-CSF) receptor are differentially utilized depending on G-CSF concentration

The granulocyte colony-stimulating factor receptor (G-CSF-R) activates multiple STAT proteins. Although the membrane-proximal cytoplasmic region of the G-CSF-R is necessary and sufficient for activation of STAT1 and STAT5, activation of STAT3 requires the membrane distal region that contains four tyrosines. Although one of these (Y704) has previously been shown to be involved in STAT3 activation from a truncated G-CSF-R derived from a patient with severe chronic neutropenia (SCN), this tyrosine is not required for STAT3 activation by the full-length G-CSF-R. To investigate possible alternative mechanisms of STAT3 activation, we generated a series of Ba/F3 cell transfectants expressing the wild-type G-CSF-R or mutant receptors that either completely lack tyrosines or retain just one of the four cytoplasmic tyrosines of the G-CSF-R. We show that, at saturating G-CSF concentrations, STAT3 activation from the full-length G-CSF-R is efficiently mediated by the C-terminal domain in a manner independent of receptor tyrosines. In contrast, at low G-CSF concentrations, Y704 and Y744 of the G-CSF-R play a major role in STAT3 activation. Both tyrosine-dependent and -independent mechanisms of STAT3 activation are sensitive to the Jak2 inhibitor AG-490, follow similar kinetics, and lead to transactivation of a STAT3 reporter construct, indicating functional equivalence. STAT3 activation is also impaired, particularly at nonsaturating G-CSF concentrations, in bone marrow cells from mice expressing a truncated G-CSF-R (gcsfr-triangle up715). These findings suggest that G-CSF-induced STAT3 activation during basal granulopoiesis (low G-CSF) and "emergency" granulopoiesis (high G-CSF) are differentially controlled. In addition, the data establish the importance of the G-CSF-R C-terminus in STAT3 activation in primary cells, which has implications for understanding why truncated G-CSF-R derived from SCN patients are defective in maturation signaling.     

Phacoemulsification for visual refraction on the clear lens. Apropos of 33 severely myopic eyes

PURPOSE: To evaluate visual benefit, predictability and complications after clear lens phakoemulsification and posterior chamber implantation in highly myopic eyes. METHODS: Thirty-three highly myopic eyes were reviewed at a mean postoperative follow-up of 27 months. The mean age of the 19 patients was 31.04 +/- 5.51 years. The mean preoperative spherical equivalent was -19.50 +/- 7.0 D (-12 to -40 D). Preoperative best spectacle corrected visual acuity was compared with the last postoperative one. Postoperative spherical equivalent was compared with the desired value. All complications were reviewed. RESULTS: A mean visual benefit of 0.24 +/- 0.18 (decimal notation) was noted (p < 0.05). The mean postoperative spherical equivalent (-2.57 +/- 1.84 D) was not significantly different from the mean previous value (p = 0.75). Retinal detachment arose in the two eyes of the same patient (incidence of 6.1%). BSCVA decreased slightly in only one of the two eyes (0.1). The incidence of Nd-YAG capsulotomy was 30%. CONCLUSION: Clear lens phakoemulsification is an effective and predictable method for the correction of high myopia. Retinal detachment is the major complication of this technique, even if a severe decrease of the visual acuity is not usual.     

Chiral separation of amines by high-performance liquid chromatography after tagging with 4-(N,N-dimethylaminosulphonyl)-7-(2-chloroformylpyrrolidin-1-yl)- 2,1,3-benzoxadiazole

Chiral tagging reagents, 4-(N,N-dimethylaminosulphonyl)-7-(2-chloroformylpyrrolidin-1 -yl)-2,1,3- benzoxadiazole (R(+)-DBD-Pro-COCl and S(-)-DBD-Pro-COCl), react with mirror image enantiomers of amines to produce corresponding diastereomers in the presence of pyridine as a catalyst. The maximal excitation and emission wavelengths of the resulting diastereomers were ca. 450 nm and 560 nm, respectively. The diastereomers derived from some aliphatic amines were resolved by a reversed-phase chromatography with water-acetonitrile or normal-phase chromatography with n-hexane-ethyl acetate as the eluent. The reactivities of both enantiomers of DBD-Pro-COCl to chiral amines were almost comparable, whereas a slight difference of fluorescence intensity was observed with S(-)-DBD-Pro-COCl. When (S-)-DBD-Pro-COCl was used as the derivatization reagent, amines corresponding to S-configuration were eluted faster than R-configuration. The opposite elution order was obtained with the use of R(+)-DBD-Pro-COCl, instead of S(-)-DBD-Pro-COCl. The Rs values obtained from 1-cyclohexylethylamine (CEA) having aliphatic ring structure was larger than those of amines (1-(1-naphthyl)ethylamine (NEA) and 1-phenylethylamine (PEA)) having aromatic ring structures.     

High- versus low-dose ACE inhibition in chronic heart failure: a double-blind, placebo-controlled study of imidapril

OBJECTIVES: To determine dose-related clinical and neurohumoral effects of angiotensin-converting enzyme (ACE) inhibitors in patients with chronic heart failure (CHF), we conducted a double-blind, placebo-controlled, randomized study of three doses (2.5 mg, 5 mg and 10 mg) of the long-acting ACE inhibitor imidapril. BACKGROUND: The ACE inhibitors have become a cornerstone in the treatment of CHF, but whether high doses are more effective than low doses has not been fully elucidated, nor have the mechanisms involved in such a dose-related effect. METHODS: In a parallel group comparison, the effects of three doses of imidapril were examined. We studied 244 patients with mild to moderate CHF (New York Heart Association class II-III: +/-80%/20%), who were stable on digoxin and diuretics. Patients were treated for 12 weeks, and the main end points were exercise capacity and plasma neurohormones. RESULTS: At baseline, the four treatment groups were well-matched for demographic variables. Of the 244 patients, 25 dropped out: 3 patients died, and 9 developed progressive CHF (3/182 patients on imidapril vs. 6/62 patients on placebo, p < 0.05). Exercise time increased 45 s in the 10-mg group (p = 0.02 vs. placebo), but it did not significantly change in the 5-mg (+16 s), and 2.5-mg (+11 s) imidapril group, compared to placebo (+3 s). Physical working capacity also increased in a dose-related manner. Plasma brain and atrial natriuretic peptide decreased (p < 0.05 for linear trend), while (nor)epinephrine, aldosterone and endothelin were not significantly affected. Renin increased in a dose-related manner, but plasma ACE activity was suppressed similarly (+/-60%) on all three doses. CONCLUSIONS: Already within 3 months after treatment initiation, high-dose ACE inhibition (with imidapril) is superior to low-dose. This is reflected by a more pronounced effect on exercise capacity and some of the neurohormones, but it does not appear to be related to the extent of suppression of plasma ACE.     

Increased MPTP neurotoxicity in vesicular monoamine transporter 2 heterozygote knockout mice

The neurotoxic action of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been proposed to be attenuated by sequestration into intracellular vesicles by the vesicular monoamine transporter (VMAT2). The purpose of this study was to determine if mice with genetically reduced levels of VMAT2 (heterozygote knockout; VMAT2 +/-) were more vulnerable to MPTP. Striatal dopamine (DA) content, the levels of DA transporter (DAT) protein, and the expression of glial fibrillary acidic protein (GFAP) mRNA, a marker of gliosis, were assessed as markers of MPTP neurotoxicity. In all parameters measured VMAT2 +/- mice were more sensitive than their wild-type littermates (VMAT2 +/+). Administration of MPTP (7.5, 15, or 30 mg/kg, b.i.d.) resulted in dose-dependent reductions in striatal DA levels in both VMAT2 +/- and VMAT2 +/+ animals, but the neurotoxic potency of MPTP was approximately doubled in the VMAT2 +/- mice: 59 versus 23% DA loss 7 days after 7.5 mg/kg dose for VMAT2 +/- and VMAT2 +/+ mice, respectively. Dopaminergic nerve terminal integrity, as assessed by DAT protein expression, also revealed more drastic reductions in the VMAT2 +/- mice: 59 versus 35% loss at 7.5 mg/kg and 95 versus 58% loss at 15 mg/kg for VMAT2 +/- and VMAT2 +/+ mice, respectively. Expression of GFAP mRNA 2 days after MPTP was higher in the VMAT2 +/- mice than in the wild-type: 15.8- versus 7.8-fold increase at 7.5 mg/kg and 20.1- versus 9.6-fold at 15 mg/kg for VMAT2 +/- and VMAT2 +/+ mice, respectively. These observations clearly demonstrate that VMAT2 +/- mice are more susceptible to the neurotoxic effects of MPTP, suggesting that VMAT2-mediated sequestration of the neurotoxin into vesicles may play an important role in attenuating MPTP toxicity in vivo.