Adaptive stiffness estimation for compliant robotic manipulation using stochastic disturbance models

To achieve haptic telepresence and proper contact behaviour, the control action of a robotic manipulator must be designed with respect to contact parameters. Unfortunately, it is hard to know these parameters exactly in unknown or partly known environments. In this case, contact instability and poor dynamic accuracy can arise due to the presence of modelling errors in the control design. To overcome these problems, online estimation of the relevant contact parameters can be performed, with corresponding adaptation of control laws. This article presents an algorithm for online stiffness estimation for compliant robotic manipulation based on the extended state-space representation of the system and force signals. No position or velocity measurements are required. The algorithm, supported by theoretical analysis, uses offline data concerning several stiffness mismatch scenarios and, through a least square error analysis, computes an estimate of the stiffness value. Simulation results are presented, with fast and accurate estimation even in the presence of noise, highlighting the merits of the method.     

Toward the DSM-V: The Withdrawal-Gate Model versus the DSM-IV in the diagnosis of alcohol abuse and dependence.

The Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) classifies as dependent many cases of mild alcohol problems. DSM-IV diagnoses have modest relationships with predictive and some concurrent validators and often improperly sequence the onset of abuse vs dependence, perhaps due to insufficient emphasis on physiological features. Testing reliability, syndrome prevalence, syndrome sequencing, and concurrent and predictive validity, this study contrasted the DSM-IV with the Withdrawal-Gate Model (WGM), in which alcohol withdrawal is necessary and sufficient for the dependence diagnosis. Clinical samples of adults (baseline n?=?318) and adolescents (baselinen?=?214) meeting abuse or dependence were assessed for DSM-IV alcohol symptoms and external measures of problem severity and reinterviewed at 6 (adults) and 12 mo (adults and adolescents). Among DSM-IV dependent cases, the WGM shifted 32% of adults and 80% of adolescents to the abuse category, making both categories more symptomatically severe, but had a negligible effect on prevalence of total alcohol diagnoses. The WGM was more reliable than the DSM-IV and temporally sequenced abuse before dependence in a greater number of cases. The WGM was superior to the DSM-IV in concurrent and predictive validity on most measures. Future diagnostic systems may be more reliable and valid if they require evidence of withdrawal for substance dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental health professionals' adaptive responses to racial microaggressions: An exploratory study.

This study examines adaptive responses that mental health professionals of color use to cope with racial microaggressions in their professional lives. Twenty-four mental health professionals from diverse ethnic backgrounds in the United States and Canada participated in focus groups discussing their experiences with racial microagressions and how they cope with them. Results of the analysis indicated that 8 primary coping themes illustrated strategies used by the participants. These include: identifying key issues in responding to racial microaggressions, self-care, spirituality, confrontation, support, documentation, mentoring, and collective organizing. Suggestions for mentoring professionals of color are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of phenoloxidase activity of carapace and viscera from cephalothorax of Norway lobster (Nephrops norvegicus)

The characterization of phenoloxidase activity was performed in both carapace and viscera extracts of Norway lobster. Phenoloxidase activity rose with increasing temperature up to 60 °C. The carapace enzymatic extract showed the highest themostability, retaining about 80% of maximum activity at 45 °C and 40% at 65 °C. On the other hand, both enzymatic extracts showed a single peak activity at neutral-slightly alkaline pH and were quite resistant to inactivation at alkaline pH (pH > 8), but phenoloxidase activity became unstable at pH lower than 5.5. The enzymatic extract obtained from viscera showed a higher affinity for catechol (K_M 5.97 mM) than carapace extract (K_M 19.40 mM). Both mono- and diphenoloxidase activities were found in carapace and viscera. Polyphenoloxidase and converted-hemocyanin into PPO-like enzyme could be the main responsible for these activities.     

Reinforcing effect of a kaolin surface-treated with diallyldimethylammonium in SBR vulcanizates

This paper examines the physico-chemical characteristics of a natural kaolin, its textural properties, pores, morphology, chemical surface, as well as chemical surface modification through treatment with quaternary ammonium salts in SBR mixes. Diallyldimethylammonium chloride was used as a quaternary alkali for surface modification of the kaolin, thus allowing the unsaturated allyl portion to covulcanize with the rubber. This achieved strong rubber-filler bonds with consequential enhancement of the technological properties of the vulcanizate.     

Coarsening of particles connected by dislocations

This work theoretically reinvestigates the coarsening of particles controlled by diffusion through a dislocation network, when the dislocation spacing of the network is larger than the maximum particle size and the volume fraction of the particles vanishes. Both a three-dimensional network and a plane one, such as that which might be encountered at a low-angle grain boundary, are treated. It is considered here that the number of dislocation pipes for diffusion increases with distance away from the particle. Under certain reasonable assumptions, at ^1/4 steady-state coarsening kinetics is found. The origin of the differences between the present kinetic results (t^1/4) and those predictions previously reported in the specialized literature (t ^1/5), for similar dislocation geometries, are discussed. The effect of the dislocation annihilation phenomenon on the growth kinetics is also examined qualitatively.     

Response surface methodology multivariate analysis of properties of high-pressure-induced fish mince gel

 Factorial analyses were performed to determine the effect of high-pressure treatment on the characteristics of blue whiting mince of good gel-forming quality. Pressure, time and temperature independently influenced gel characteristics. Temperature had the greatest influence of the three. High-pressure gels were generally distinguished by lower adhesiveness, higher water-holding capacity and less yellowness than heat-induced gels. The combination of pressure and temperature produced more elastic gels, whereas gels made under high pressure at chilling temperatures were much harder, more deformable and more cohesive. There was no correlation between elasticity and deformability.     

Effects of a citrus based juice on biomarkers of oxidative stress in metabolic syndrome patients

Bioactive substances found in numerous foods can be successfully and safely used to modify various cellular functions and affect the oxidative stress. The aim of this study was to analyze the effect of a citrus-based juice (juice citrus (95%) with 5% of aronia extract (Aronia melanocarpa)) on biomarkers of oxidative stress in patients with metabolic syndrome compared with healthy individuals. The study comprised 20 healthy subjects and 33 patients with metabolic syndrome. Eighteen patients consumed daily 300 mL of a citrus-based juice during 6 months and 15 patients consumed 300 mL of a placebo beverage. The control group consumed a citrus-based juice (CJ). Before, and at sixth months after consuming of a citrus-based juice the following parameters were determined: 15-isoprostane F₂, 8-hydroxydeoxyguanosine (8-OHdG), reduced and oxidized glutathione (GSH/GSSH), carbonyl groups and oxidized LDL (ox-LDL). After consuming CJ during 6 months the values of 8-OHdG, carbonyl groups and LDL-ox decreased in both analyzed groups and the values of GSH/GSSH increased. Significant differences were observed in both groups. Thus consumption of citrus-based juice improved the biomarkers of oxidative stress in metabolic syndrome patients.     

Adhesion of Listeria monocytogenes to materials commonly found in domestic kitchens

The aim of this work was to investigate the adhesion of Listeria monocytogenes ATCC 15313 to glass, granite, marble, polypropylene from a bowl (PPb), polypropylene from a cutting board (PPcb) and stainless steel (SS), which are materials commonly used in kitchens. Marble and granite were chosen because they are applied as kitchen bench covers and pavements in many countries and there are no literature reports on their behaviour in terms of microbial adhesion. The effect of surface hydrophobicity and roughness on the adhesion process was also analysed. The results showed that the highest extent of adhesion of L. monocytogenes occurred to stainless steel, followed by glass and in less extent to the other materials studied. However, it was not possible to establish a correlation between surface hydrophobicity or roughness and the extent of adhesion of L. monocytogenes . The adherence of L. monocytogenes should be dependent on other factors, like the presence of exopolymers and surface charge.     

Albumin causes a synergistic increase in the antioxidant activity of green tea catechins in oil-in-water emulsions

Model oil-in-water emulsions containing epicatechin (EC) and epigallocatechin gallate (EGCG) showed a synergistic increase in stability in emulsions containing added albumin. EGCG showed a stronger synergy (35%) with ovalbumin than did EC. Oxidation of the oil was monitored by determining peroxide values and hexanal contents. The effect of bovine serum albumin (BSA) on model oil-in-water emulsions containing each of the green tea catechins [epicatechin gallate (ECG), EGCG, EC and epigallocatechin (EGC)] was studied during storage at 30 °C. The green tea catechins showed moderate antioxidant activity in the emulsions with the order of activity being ECG ≈ EGCG > EC > EGC. Although BSA had very little antioxidant activity in the absence of phenolic antioxidants, the combination of BSA with each of the catechins showed strong antioxidant activity. BSA, in combination with EC, EGCG or EGC, showing the strongest antioxidant activity with good stability after 45 days storage. Model experiments with the catechins stored with BSA in aqueous solutions confirmed that protein–catechin adducts with antioxidant activity were formed between the catechins and protein. The antioxidant activity of the separated protein–catechin adducts increased strongly with storage time and was stronger for EGCG and ECG than for EC or EGC.