Conceptual Design and Workspace Analysis of an Exechon-inspired Parallel Kinematic Machine

Inspired by the commercial application of the Exechon machine, this paper proposed a novel parallel kinematic machine (PKM) named Exe-Variant. By exchanging the sequence of kinematic pairs in each limb of the Exechon machine, the Exe-Variant PKM claims an arrangement of 2UPR/1SPR topology and consists of two identical UPR limbs and one SPR limb. The inverse kinematics of the 2UPR/1SPR parallel mechanism was firstly analyzed based on which a conceptual design of the Exe-Variant was carried out. Then an algorithm of reachable workspace searching for the Exe-Variant and the Exchon was proposed. Finally, the workspaces of two example systems of the Exechon and the Exe-Variant with approximate dimensions were numerically simulated and compared. The comparison shows that the Exe-Variant possesses a competitive workspace with the Exechon machine, indicating it can be used as a promising reconfigurable module in a hybrid 5-DOF machine tool system.

A comparação da qualidade dos momentos de interação em jogo livre entre mãe/ filho - pai /filho e mãe/criança – técnica/criança entre os 13 e 15 meses de idade

Dissertação apresentada para obtenção do grau de Mestre em Ciências da Educação Área de especialização em Intervenção Precoce

Fault tolerance force for redundant manipulators

Fault tolerant manipulators maintain their trajectory even if their joint/s fails. Assuming that the manipulator is fault tolerant on its trajectory, fault tolerant compliance manipulators provide required force at their end-effector even when a joint fails. To achieve this, the contributions of the faulty joints for the force of the end-effector are required to be mapped into the proper compensating joint torques of the healthy joints to maintain the force. This paper addresses the optimal mapping to minimize the force jump due to a fault, which is the maximum effort to maintain the force when a fault occurs. The paper studies the locked joint fault/s of the redundant manipulators and it relates the force jump at the end-effector to the faults within the joints. Adding on a previous study to maintain the trajectory, in here the objective is to providing fault tolerant force at the end-effector of the redundant manipulators. This optimal mapping with minimum force jump is presented using matrix perturbation model. And the force jump is calculated through this model for single and multiple joints fault. The proposed optimal mapping is used in different fault scenarios for a 5-DOF manipulator; also it is deployed to compensate the force at the end-effector for the 5-DOF manipulator through simulation study and the results are presented.

Grasping virtual objects with multi-point haptics

The majority of commercially available haptic devices offer a single point of haptic interaction. These devices are limited when it is desirable to grasp with multiple fingers in applications including virtual training, telesurgery and telemanipulation. Multipoint haptic devices serve to facilitate a greater range of interactions. This paper presents a gripper attachment to enable multi-point haptic grasping in virtual environments. The approach employs two Phantom Omni haptic devices to independently render forces to the user's thumb and other fingers. Compared with more complex approaches to multi-point haptics, this approach provides a number of advantages including low-cost, reliability and ease of programming. The ability of the integrated multi-point haptic platform to interact within a CHAI 3D virtual environment is also presented.

Parallel manipulators with a rotation-symmetric arm system

Parallel manipulators with a rotation-symmetric arm system possess all the typical advantages of parallel robots, such as high acceleration and high-accuracy positioning. Contrary to the majority of proposed parallel manipulators, the rotation-symmetric arm system leads to a large workspace in relation to the footprint of the manipulator. This paper focuses on a subclass of these manipulators with additional favorable qualities, including low inertia and high eigenfrequencies. These qualities are achieved using only 5-DOF lower arm links and by mounting all actuators on the nonmoving base column of the manipulator. The common feature of all previously proposed manipulators in this subclass is identified and several novel 3-DOF and 4-DOF members are introduced.

Integrating kinect and haptics for interactive STEM education in local and distributed environments

Skill shortage is a realistic social problem that Australia is currently facing, especially in the fields of Science, Technology, Engineering and Mathematics (STEM). Various approaches have been proposed to soften this issue. By now the most successful approach is to attract pre-university youth and university freshmen into those fields before they make a decision on future subjects by introducing them with interactive, modifiable and inspiring virtual environments, which incorporates most essential knowledge of STEM. We propose to design a comprehensive virtual reality platform with immersive interactions, pluggable components and flexible configurations. It also involves haptics, motion capture and gesture recognition, and could be deployed in both local and distributed environments. The platform utilizes off the shelf low cost haptics and motion capture products, however the fidelity can be maintained at a good level. The proposed platform has been implemented with different configurations and has been tested on a group of users. Preliminary test results show that the interactivity, flexibility and fidelity of the platform are highly appreciated by users. User surveys also indicate that the proposed platform could help pre-university students and university freshmen build an overview of various aspects of STEM education. Besides, users are also positive on the fact that the platform enabled them to identify the challenges for higher education in STEM by providing them opportunities to interactively modify system configurations and instantly experience the corresponding results both visually and haptically.

A method for extending planar axis-symmetric parallel manipulators to spatial mechanisms

This paper investigates axis-symmetric parallel manipulators, composed of a central base column and an arm system able to rotate around this column. The arm system includes several actuated upper arms, each connected to a manipulated platform by one or more lower arm linkages. Such manipulators feature an extensive positional workspace in relation to the manipulator footprint and equal manipulator properties in all radial half-planes defined by the common rotation-axis of the upper arms. The similarities between planar manipulators exclusively employing 2-degrees-of-freedom (2-DOF) lower arm linkages and lower mobility spatial manipulators only utilising 5-DOF lower arm linkages are analysed. The 2-DOF linkages are composed of a link with a 1-DOF hinge on both ends whilst the 5-DOF linkages utilise 3-DOF spherical joints and 2-DOF universal joints. By employing a proposed linkage substitution scheme, it is shown how a wide range of spatial axis-symmetric parallel manipulators can be derived from a limited range of planar manipulators of the same type.

Produção de β-ecdisona em Pfaffia glomerata (Spreng.) Pedersen em função da adubação orgânica em 6 épocas de crescimento

O trabalho teve como objetivo verificar a influência da adubação orgânica em 6 épocas de crescimento na produção de β-ecdisona por plantas de Pfaffia glomerata. O experimento foi conduzido na Fazenda Santo Antonio do Araquá, distrito de Catâneo Ângelo, município de São Manuel, São Paulo, Brasil. Utilizou-se o delineamento de blocos ao acaso, num esquema fatorial 5x6, com quatro repetições, considerando-se 8 plantas úteis por parcela. Os blocos foram constituídos de 6 épocas de crescimento (60, 120, 180, 240, 300 e 360 dias após a germinação) e de 5 doses de esterco de galinha curtido [testemunha (sem adubação), 15, 30, 45 e 60 t ha-1]. Após cada colheita, as raízes das plantas foram secas em estufa com circulação de ar forçada a 40ºC e pesadas para posterior extração do β-ecdisona, seguindo metodologia desenvolvida por Magalhães (2000). Os resultados foram submetidos à análise de variância e ao teste de separação de médias de Scott Knott, todos a 5% de probabilidade. Quando ocorreu interação os resultados foram avaliados usando-se análise de regressão polinominal. O teor de β-ecdisona não foi influenciado pelas doses de adubo e nem pela época do crescimento das plantas. Porém a quantidade total de β-ecdisona por raiz foi influenciada pela época de crescimento, sendo que aos 360 dias após a emergência ocorreu uma maior quantidade do princípio ativo em todos os tratamentos. Apesar de não diferir estatisticamente dos demais tratamentos, aos 360 dias após a emergência das plantas, o tratamento 30 t ha-1 foi o que proporcionou maior quantidade de β-ecdisona.

Composition and abundance of shrimp species (penaeidea and caridea) in Fortaleza Bay, Ubatuba, São Paulo, Brazil

The abundance and spatio-temporal distribution of the caridean and penaeid fauna from Fortaleza Bay, Ubatuba, São Paulo, Brazil, were analyzed. Seven transects were sampled over a one year period from November 1988 to October 1989. A total of 17047 shrimps were captured, representing 13 species belonging to 5 families. The interaction of temperature and type of sediment was fundamental in determining the presence and abundance of shrimp species in the area.

Influence of nearest-neighbor Coulomb interactions on the phase diagram of the ferromagnetic Kondo model

The influence of a nearest-neighbor Coulomb repulsion of strength V on the properties of the ferromagnetic Kondo model is analyzed using computational techniques. The Hamiltonian studied here is defined on a chain using localized S = 1/2 spins, and one orbital per site. Special emphasis is given to the influence of the Coulomb repulsion on the regions of phase separation recently discovered in this family of models, as well as on the double-exchange-induced ferromagnetic ground state. When phase separation dominates at V= 0, the Coulomb interaction breaks the large domains of the two competing phases into small islands of one phase embedded into the other. This is in agreement with several experimental results, as discussed in the text. Vestiges of the original phase separation regime are found in the spin structure factor as incommensurate peaks, even at large values of V. In the ferromagnetic regime close to density n = 0.5, the Coulomb interaction induces tendencies to charge ordering without altering the fully polarized character of the state. This regime of charge-ordered ferromagnetism may be related with experimental observations of a similar phase by Chen and Cheong [Phys. Rev. Lett. 76, 4042 (1996)]. Our results reinforce the recently introduced notion [see, e.g., S. Yunoki et al., Phys. Rev. Lett. 80, 845 (1998)] that in realistic models for manganites analyzed with unbiased many-body techniques, the ground state properties arise from a competition between ferromagnetism and phase-separation - charge-ordering tendencies. ©1999 The American Physical Society.

Abordagens estatísticas em testes de resistência de união entre dentina bovina, sistema adesivo e resina composta

Pós-graduação em Odontologia Restauradora - ICT

The panicolytic-like effect of fluoxetine in the elevated T-maze is mediated by serotonin-induced activation of endogenous opioids in the dorsal periaqueductal grey

Serotonin (5-HT), opioids and the dorsal periaqueductal grey (DPAG) have been implicated in the pathophysiology of panic disorder. In order to study 5-HT-opioid interaction, the opioid antagonist naloxone was injected either systemically (1 mg/kg, i.p.) or intra-DPAG (0.2 mu g/0.5 mu L) to assess its interference with the effect of chronic fluoxetine (10 mg/kg, i.p., daily for 21 days) or of intra-DPAG 5-HT (8 mu g/0.5 mu L). Drug effects were measured in the one-escape task of the rat elevated T-maze, an animal model of panic. Pretreatment with systemic naloxone antagonized the lengthening of escape latency caused by chronic fluoxetine, considered a panicolytic-like effect that parallels the drug's therapeutic response in the clinics. Pretreatment with naloxone injected intra-DPAG antagonized both the panicolytic effect of chronic fluoxetine as well as that of 5-HT injected intra-DPAG. Neither the performance of the inhibitory avoidance task in the elevated T-maze, a model of generalized anxiety nor locomotion measured in a circular arena was affected by the above drug treatments. These results indicate that the panicolytic effect of fluoxetine is mediated by endogenous opioids that are activated by 5-HT in the DPAG. They also allow reconciliation between the serotonergic and opioidergic hypotheses of panic disorder pathophysiology.

Characterization of the interactions between fibronectin and the Borrelia burgdorferi lipoprotein, BBK32

The findings presented in this dissertation detail the complex interaction between BBK32 and fibronectin and describe novel consequences of the interaction. BBK32 is a fibronectin-binding protein on Borrelia burgdorferi, the causative agent of Lyme disease. We found that BBK32 contains multiple fibronectin-binding motifs, recognizing the fibronectin N-terminal domain (NTD) and the gelatin binding domain (GBD) in an anti-parallel order, where corresponding sites in BBK32 and fibronectin are aligned so that there is a one-to-one interaction between the proteins. While characterizing this interaction, we discovered that binding of BBK32 to the GBD inhibits the migration stimulating factor's (MSF) motogenic activity. In the presence of BBK32, endothelial cells do not migrate in response to increasing concentrations of MSF or the GBD. MSF is found under wound healing conditions, and inhibition of its activity may allow the tick-transmitted spirochetes to delay wound healing and to establish an infection. ^ Biophysical structural studies, designed to identify a mechanism of interaction, revealed that BBK32 binding to the NTD leads to the unfolding of plasma fibronectin, which exposes α5β1 integrin recognition motifs. Binding assays demonstrate that the BBK32-NTD interaction enhances the plasma fibronectin-α5β1 integrin interaction, which may allow B. burgdorferi to invade host cells, and thereby evade the host immune system. ^ We also determined that BBK32 binds fibronectin F3 modules, which leads to plasma fibronectin aggregation and induction of superfibronectin. The resulting superfibronectin is conformationally distinct from plasma and cellular fibronectin, and can inhibit endothelial cell proliferation. BBK32's active superfibronectin-forming motif has been located to a region between residues 160 and 175, which contains two sequence motifs that are also found in anastellin, the only other known superfibronectin-inducing protein. ^ A potential consequence of BBK32-induced superfibronectin formation was identified. BBK32-induced superfibronectin formation results in the exposure of α4β1 integrin recognition sequences in fibronectin. The α4β1 integrin is required for leukocyte transendothelial cell migration. BBK32-induced superfibronectin inhibits this activity. The inhibition of leukocyte recruitment to the infection site may slow the activity of the host immune system, and permit the spirochetes to establish an infection. ^

Purification and Characterization of AsES Protein A Subtilisin Secreted by Acremonium Strictum is a Novel Plant Defense Elicitor.

In this work, the purification and characterization of an extracellular elicitor protein, designated AsES, produced by an avirulent isolate of the strawberry pathogen Acremonium strictum, are reported. The defense eliciting activity present in culture filtrates was recovered and purified by ultrafiltration (cutoff, 30 kDa), anionic exchange (Q-Sepharose, pH 7.5), and hydrophobic interaction (phenyl-Sepharose) chromatographies. Two-dimensional SDS-PAGE of the purified active fraction revealed a single spot of 34 kDa and pI 8.8. HPLC (C2/C18) and MS/MS analysis confirmed purification to homogeneity. Foliar spray with AsES provided a total systemic protection against anthracnose disease in strawberry, accompanied by the expression of defense-related genes (i.e. PR1 and Chi2-1). Accumulation of reactive oxygen species (e.g. H2O2 and O2̇̄) and callose was also observed in Arabidopsis. By using degenerate primers designed from the partial amino acid sequences and rapid amplification reactions of cDNA ends, the complete AsES-coding cDNA of 1167 nucleotides was obtained. The deduced amino acid sequence showed significant identity with fungal serine proteinases of the subtilisin family, indicating that AsES is synthesized as a larger precursor containing a 15-residue secretory signal peptide and a 90-residue peptidase inhibitor I9 domain in addition to the 283-residue mature protein. AsES exhibited proteolytic activity in vitro, and its resistance eliciting activity was eliminated when inhibited with PMSF, suggesting that its proteolytic activity is required to induce the defense response. This is, to our knowledge, the first report of a fungal subtilisin that shows eliciting activity in plants. This finding could contribute to develop disease biocontrol strategies in plants by activating its innate immunity.

An investigation into the pharmacology of tics and tic-like movements

The study of tic-like movements in mice has demonstrated close parallels both in characteristics and in pharmacology with the tics which occur in TS. Head-shakes and/or other tic-like behaviours occurring spontaneously or induced by the selective 5-HT2/1C agonist DOI, alpha-melanocyte stimulating hormone, adrenocorticotrophic hormone (1-39), thyrotropin releasing hormone, or RX336-M were blocked when tested with neuroleptics such as haloperidol and/or the alpha-2 adrenoceptor agonist clonidine. The selective dopamine D1 antagonists SCH23390 and SCH39166 dose-dependently blocked spontaneous and DOI head-shakes but the selective dopamine D2 antagonists sulpiride and raclopride were ineffective. The 5-HT1A receptor agonists 8-OH-DPAT, ipsapirone, gepirone, MDL 73005EF and buspirone (i.p) dose-dependently blocked DOI head-shakes, pindolol blocked the inhibitory effect of 8-OH-DPAT on DOI head-shakes. Parachlorophenylalanine blocked the inhibitory effect of 8-OH-DPAT and buspirone, suggesting that the 5-HT1A receptor involved is located presynaptically. The alpha-2 adrenoceptor antagonists yohimbine, idazoxan, 1-PP and RX811059 prevented the inhibitory effect of 8-OH-DPAT on DOI head-shakes suggesting that this 5-HT1A - 5-HT2 receptor interaction is under the modulatory control of adrenoceptors. Because kynurenine has previously been found to potentiate head-shaking, plasma kynurenine concentrations were measured in seven TS patients and were significantly higher than controls, but neopterin and biopterin were unchanged. The relationship between tic-like movements in rodents and their implications for understanding the aetiology and treatment of TS is discussed.