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The common chimpanzee (Pan troglodytes) is a facultative biped and our closest living relative. As such, the musculoskeletal anatomies of their pelvis and hind limbs have long provided a comparative context for studies of human and fossil hominin locomotion. Yet, how the chimpanzee pelvis and hind limb actually move during bipedal walking is still not well defined. Here, we describe the three-dimensional (3-D) kinematics of the pelvis, hip, knee and ankle during bipedal walking and compare those values to humans walking at the same dimensionless and dimensional velocities. The stride-to-stride and intraspecific variations in 3-D kinematics were calculated using the adjusted coefficient of multiple correlation. Our results indicate that humans walk with a more stable pelvis than chimpanzees, especially in tilt and rotation. Both species exhibit similar magnitudes of pelvis list, but with segment motion that is opposite in phasing. In the hind limb, chimpanzees walk with a more flexed and abducted limb posture, and substantially exceed humans in the magnitude of hip rotation during a stride. The average stride-to-stride variation in joint and segment motion was greater in chimpanzees than humans, while the intraspecific variation was similar on average. These results demonstrate substantial differences between human and chimpanzee bipedal walking, in both the sagittal and non-sagittal planes. These new 3-D kinematic data are fundamental to a comprehensive understanding of the mechanics, energetics and control of chimpanzee bipedalism.

Barium strontium titanate (Ba0.8Sr0.2TiO3, BST) nanocrystalline ceramics have been synthesized by high energy ball milling. As the sintering temperature increases from 1200 °C to 1350 °C, the average grain size of BST ceramics increases from 86 nm to 123 nm. The X-ray diffraction (XRD) studies show that these ceramics are tetragonal. The phase and grain size of the sintered pellets have been estimated from the XRD patterns, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The effect of grain size on dielectric and ferroelectric properties is studied. The dielectric and piezoelectric parameters are greatly improved at room temperature with increase in grain size. The Curie transition temperature is found to shift slightly towards higher temperatures as the grain increases from 86 nm to 123 nm. The coercive field decreases and the remnant polarization and spontaneous polarization increase as the grain size of BST nano ceramics increases. These ceramics are promising materials for tunable capacitor device applications.

The abnormal aggregation of tau protein into paired helical filaments (PHFs) is one of the hallmarks of Alzheimer’s disease. Although some small molecules capable of inhibiting the aggregation have...

Inspired by the enormous importance attributed to the structure and function of human telomeric DNA, we focus our attention on the interaction of [Ru(bpy)(2)(dppz)](2+) with the guanine-rich single-strand oligomer 5'-AGGGTTAGGGTTAGGGTTAGGG-3' (22AG) and the complementary cytosine-rich strand (22CT). In Na(+) buffer, 22AG may adopt an antiparallel basket quadruplex, whereas, it favours a mixed parallel/antiparallel structure in K(+) buffer. 22CT may self-associate at acidic pH into an i-motif. In this paper, the interaction between [Ru(bpy)(2)(dppz)](2+) and each unusual DNA was evaluated. It was interesting that [Ru(bpy)(2)(dppz)](2+) could promote the human telomeric repeat 22AG to fold into intramolecular antiparallel G-quadruplex without any other cations. What's more, [Ru(bpy)(2)(dppz)](2+) was found to have a strong preference for binding to G-quadruplexes that were induced through either Na(+) or K(+), while weak binding to i-motif was observed. The results also indicated that [Ru(bpy)(2)(dppz)](2+) could serve as a prominent molecular "light switch" for both G-quadruplexes, revealing a potential application of the title complex in luminescent signaling of G-quadruplex DNA.

Variability in motor rehabilitation program outcomes can be attributed not only to individual components (human patient/rehabilitation equipment) but also to their system-level interactions. Thus, effective deployment of a rehabilitation program depends upon: 1) suitable therapist selection of user-device ergonomics; 2) adjustable device settings; and 3) exercise regimen parameters; to achieve desired system-level motor performance. In this paper, we discuss aspects of creation of a virtual design environment, leveraging tools from musculoskeletal analysis, optimization, and simulation-based design, to permit therapists to rapidly evaluate and systematically customize rehabilitation programs. Specifically, this framework is intended to facilitate 1) parametric study of ergonomic/device/regimen settings on musculoskeletal performance; 2) use of design tools such as optimization for decision support in arriving at the best program; and 3) scaffolded examination of linkage between form and function by iterative what-if type of analyses. We use two case studies (bicep-curling and motor rehabilitative driving) to highlight benefits of such simulation-based rehabilitation program evaluation.

The colored noise in a single-mode laser with injected signal is investigated by the method of two-dimensional unified colored noise approximation. The normalized correlation function , the intensity correlation time and effective eigenvalue are calculated. The effects of the injected signal , colored noise strength and the noise correlation time on the dynamical properties of the single-mode laser are discussed.

The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturation laser theory with backscattering. The theoretical predictions are in good agreement with the experimental measurements. Further investigation reveals that the backscattering can reduce the fluctuations in the system while the full saturation effect plays a major role when the laser is operated above threshold. It is also quite important to notice that the injected signal can drive the weak mode from incoherent light to coherent light.

The dynamical properties of two-mode ring laser with different values of mode coupling constants are investigated by the full saturation laser theory with an injected signal. By a one-dimensional approximation, the intensity correlation time and effective eigenvalue are calculated. The effects of backscattering and injected signal are discussed.

The dynamical properties of a two-mode ring laser with both the additive and multiplicative noises are analyzed. Time-dependent probability density is obtained by the method of one-dimensional approximation. Some special behaviors of and are discussed when the multiplicative pump noise and saturation effect are included in the laser theory.

The title complex, [Co(C(15)H(12)N(3)O(2)S)(2)], consists of an octahedrally coordinated Co(II) ion, with two crystallographically independent 1,4-dibenzoylthiosemicarbazidate ligands in a tridentate mer coordination [Co-O = 2.064 (3)-2.132 (3) A and Co-N = 2.037 (3)-2.043 (3) A]. There are intermolecular N-H...S hydrogen bonds involving one ligand and strong pi-pi stacking interactions involving the other ligand, resulting in a three-dimensional supramolecular framework. The hydrogen bonds and pi-pi interactions, as well as different intramolecular aryl-benzamide H-C...H(-N) distances, give rise to a difference in conformation between the two ligands.

As an interdisciplinary field lying at the intersection of biology and robotics, bio-inspired robotics has seen considerable interest from a research, education, and ultimately application perspective. The scope of this interest has ranged from creating and operating walking, crawling, and flying robots based on biological counterparts; to evaluating biological algorithms for potential engineering applications; to deconstructing the functioning of living organisms from the macro- to the microlevels; and ultimately to constructing the next generation of bio-inspired robots from the bottom up. Significant synergies are forthcoming from such an approach, but numerous limitations still exist. We begin with the discussion of general principles behind taking inspiration from a biological source and converting it into implementable engineering concepts using case studies of bird-inspired robots, snake-inspired robots, and mastication robots. These case studies describe how useful features of the biological creatures were selected and simplified so that they can be implemented using the existing technologies.

Parallel-architecture haptic devices offer significant advantages over serial-architecture counterparts in applications requiring high stiffness and high accuracy. To this end, many haptic devices have been created and deployed by modularly piecing together several serial-chain arms to form an in-parallel system. Furthermore, recent haptic devices design such as the Sensable’s PHANToM Premium line of haptic devices and Quanser’s High Definition Haptic Device (HD)2 placed the 2nd actuated joint (of a 2-DOF RR serial manipulator) at the base of the device that allowed the control of the 2nd joint through a parallelogram/fourbar structure. This design is favorable from the view point of reducing the overall weight that the first motor has to carry. However, such design choices can affect the overall system performance which depends both on the nature of the individual arms as well as their interactions. In this paper, we build on the rich theoretical background of constrained articulated mechanical systems to provide a systematic framework for formulation of system-level kinematic performance from individual-arm characteristics. Specifically, we discuss: (i) development of pertinent symbolic equations; (ii) generalization to arbitrary architectures; and (iii) combined symbolic/numeric analyses of performance, focusing on manipulability and stiffness. These aspects are illustrated using the example of Quanser High Definition Haptic Device (HD)2 — an in-parallel haptic device formed by coupling two 3-link PHANToM 1.5 type serial chain manipulators with appropriate passive joints.

The loss of metal homeostasis and the toxic effect of metal ion are important events in neurodegenerative and age-related diseases, such as Alzheimer's disease (AD). For the first time, we investigated the impacts of mercury(II) ions on the folding and aggregation of Alzheimer's tau fragment R2 (residues 275-305: VQIIN KKLDL SNVQS KCGSK DNIKH VPGGGS), corresponding to the second repeat unit of the microtubule-binding domain, which was believed to be pivotal to the biochemical properties of full tau protein. By ThS fluorescence assay and electron microscopy, we found that mercury(II) dramatically promoted heparin-induced aggregation of R2 at an optimum molar ratio of 1: 2 (metal: protein), and the resulting R2 filaments became smaller. Isothermal titration calorimetry (ITC) experiment revealed that the strong coordination of mercury(II) with R2 was an enthalpy-controlled, entropy-decreased thermodynamic process. The exceptionally large magnitude of heat release (ΔH₁ = -34.8 Kcal mol⁻¹) suggested that the most possible coordinating site on the R2 peptide chain was the thiol group of cysteine residue (Cys291), and this was further confirmed by a control experiment using Cys291 mutated R2. Circular dichroism spectrum demonstrated that this peptide underwent a significant conformational change from random coil to β-turn structure upon its binding to mercury(II) ion. This study was undertaken to better understand the mechanism of tau aggregation, and evaluate the possible role of mercury(II) in the pathogenesis of AD.

Parallel-architecture haptic devices offer significant advantages over serial-architecture counterparts in applications requiring high stiffness and high accuracy. To this end, many haptic devices have been created and deployed by modularly piecing together several serial-chain arms to form an in-parallel system. However, the overall system performance depends both on the nature of the individual arms as well as their interactions. We build on the rich theoretical background of constrained articulated mechanical systems to provide a systematic framework for formulation of system-level kinematic performance from individual-arm characteristics. Specifically, we develop the system-level kinematic model in a symbolic (yet algorithmic) fashion that facilitates: (i) computational development of pertinent symbolic equations; (ii) generalization to arbitrary architectures; and (iii) combined symbolic/numeric analyses of performance (workspace, singularities, design sensitivities). These various aspects are illustrated using the example of the Quanser High Definition Haptic Device (HD)2 — an in-parallel haptic device formed by coupling two 3-link Phantom 1.5 type serial chain manipulators with appropriate passive joints. We also briefly discuss aspects of ongoing work for design-prototyping and validation, taking advantage of tools from Virtual Prototyping and Hardware-in-the-Loop testing.

Cable robots have seen considerable recent interest ensuing from their ability to combine a large workspace with significant payload capacity. However, the cables can apply forces to the end-effector only when they are in tension, and thus form a subclass of control problems requiring unilateral control inputs. Furthermore, actuation redundancy occurs when surplus cables are introduced within the system. On one hand, such redundancy needs to be carefully resolved for accurate tracking of the task. On the other hand, it allows the redistribution of the actuation forces to satisfy some secondary criteria. In this paper, we apply such redundancy for enhanced trajectory tracking by actively controlling the task stiffness of the end-effector. The scheme allow us to specify a lower bound of the task stiffness, which is intended to provide improved trajectory tracking and disturbance rejection performance. Finally, we illustrate the improved control performance within a virtual prototype cosimulation framework.

[Ru(phen)(2)(dppz)](2+)can serve as a prominent molecular "light switch" for G-quadruplexes and i-motif, but it preferentially binds to G-quadruplexes over i-motif.

Exoskeletons are a new class of articulated mechanical systems whose performance is realized while in intimate contact with the human user. The overall performance depends on many factors including selection of architecture, device, parameters and the nature of the coupling to the human, offering numerous challenges to design-evaluation and refinement. In this paper, we discuss merger of techniques from the musculoskeletal analysis and simulation-based design to study and analyze the performance of such exoskeletons. A representative example of a simplified exoskeleton interacting with and assisting the human arm is used to illustrate principal ideas. Overall, four different case-scenarios are developed and examined with quantitative performance measures to evaluate the effectiveness of the design and allow for design refinement. The results show that augmentation by way of the exoskeleton can lead to a significant reduction in muscle loading.

In recent years there has been a significant increase in the variety and complexity of Articulated-Multi-Body-Systems (AMBS) used in various applications. There is also increased interest in the model-based design-refinement and controller-development, which is critically dependent upon availability of underlying plant-models. Kinematic and dynamic plant-models for AMBSs can be formulated by systematic application of physics postulates. This process, in its various variants, forms the basis of various mechanisms/robotics courses. However, the type and complexity of the example systems is often limited by the tractability of first generating and subsequently analyzing complex equations-of-motion. Nevertheless, using simpler examples alone may sometimes fail to capture important physical phenomena (e.g. gyroscopic, coriolis). Hence, we examine the use of some contemporary symbolic- and numeric-computation tools to assist with the automated symbolic equation generation and subsequent analysis. We examine a host of examples beginning with simple pendulum, double pendulum; building up to intermediate examples like the four-bar mechanism and finally examine the implementation of 3-P RR and 3-R RR planar parallel platform mechanisms. The principal underlying philosophy of our effort is to establish linkage between traditional modeling approaches and use of these contemporary tools. We also try to make a case for use of automatic symbolic computation and manipulation as a means for enhancing understanding of both basic and advanced AMBS concepts. Lastly, we document our efforts towards creation of self-paced tutorials and case-studies that serve to showcase the benefits.Copyright © 2010 by ASME

A critical precursor to deployment of model-based controllers for articulated-mechanical-systems is availability of a systematic means for generating plant-model-equations. However, the complexity and tractability of generating and analyzing models serves to limit the size of the chosen examples. Hence, we examine the use of contemporary symbolic-computation tools to assist with the automated symbolic equation generation and subsequent analysis to support control systems course work. In particular, we seek to establish linkage between traditional-approach and block-diagram-based symbolic-modeling and controller-development. The Furuta Pendulum example allows us to showcase the emergence of model-complexity, even in relatively-simple two-jointed mechanical system, while studying various aspects of model-creation, model-linearization and model-based controller development in a timely manner.Copyright © 2010 by ASME

The potential for use of robotic systems in remote applications arenas has long motivated development of robust and stable means of teleoperated control of slave systems. However, telerobotic systems face challenges stemming from the devices themselves, environmental factors, communication and control complexities. To address these challenges, we will adopt the passivity based synchronization framework [1] and study its applicability to safely synchronize two heterogeneous Lagrangian systems. Within this framework, an adaptive controller identifies and stabilizes the dynamics of the master and slave systems and renders the dynamics passive to a secondary coupling input. The passive mapping used to couple the output states of the master and slave systems and is made insensitive to lossy and delayed communication medium. Specifically, an adaptive passive synchronization teleoperation controller is developed between an Omni haptic device that serves as our master and a differentially driven nonholonomic Wheel Mobile Robot (WMR) as the slave system. A battery of hardware-in-the-loop simulations are used to verify the proposed controller.

Doctors, dentists, nurses, athletic trainers, occupational therapists and allied health-care professionals are expected to learn the linkage between anatomy, physiology and ultimately functional-performance of muscles i.e. how muscles affect movement or which sets of muscles carry various loads. However the extent of understanding of functional-performance that can be imparted in a didactic-lecture or cadaver-lab setting of a ldquoGross Anatomyrdquo class is limited. Hence we seek to create the architecture and algorithms for scaffolded interaction with human musculoskeletal simulation models (virtual prototypes) that can make varied ldquowhat-ifrdquo type analyses and hypothesis-testing possible. This is very pertinent in the context of the target audience of healthcare professionals who may lack prior exposure to such virtual computational scenario testing tools. Providing such access is vital to training of the next generation of health care professionals to leverage ubiquitous computing and the quantitative-paradigm.

In the past decade, ongoing revolutions in computing effectiveness and miniaturization of processors/sensors/actuators have facilitated the transition of research focus from an individual mobile robot to networked distributed teams of mobile robots. The development of effective motion-planning methods for such collectives is critical to realizing the full potential of the group in numerous applications ranging from reconnaissance, foraging, herding to cooperative payload transport. While considerable literature exists for motion planning of individual mobile agents, the renewed challenge lies in creating motion plans for the entire team while incorporating notions such as cooperation. The “formation” paradigm has emerged as a convenient mechanism for abstraction and coordination with approaches ranging from leader-following (Wang, 1991; Desai et al., 2001), virtual structures (Lewis and Tan, 1997; Beard et al., 2001) and virtual leaders (Leonard and Fiorelli, 2001; Ogren et al., 2002). The group control problem now reduces to a well-known single-agent control problem from which the other agents derive their control laws but requires communication of some coordination information. Early implementations involved the kinematic specification of the followers’ motion-plans as a “prescribed motions” relative to a team-leader without the ability to affect the dynamics of the leader. Subsequent approaches have incorporated some form of “formation-feedback” from the members to the overall group using natural or artificially introduced dynamics within the constraints. The formation paradigm has evolved to allow prescription of parameterized formation maneuvers and group feedback (Egerstedt and Hu, 2001; Young et al., 2001; Ogren et al., 2002). From these seemingly disparate approaches, a dynamic system-theoretic perspective has emerged for examining the decentralized multiagent “behavioral control” in the context of “formations” (Lawton et al., 2000; Egerstedt and Hu, 2001; Leonard and Fiorelli, 2001; Young et al., 2001; Ogren et al., 2002; Olfati-Saber and Murray, 2006). “Behavioral” control laws, derived implicitly as gradients of limited-range artificial potentials, can be implemented in a decentralized manner while permitting a Lyapunov-based analysis of formation maintenance. Various variants of the Artificial Potential Field (APF) framework have been leveraged in implementing such behavioral motion-planning/control of robot collectives due to their seeming ease of formulation, decentralization and scalability. However, we note that while

The Steer-By-Wire (SBW) paradigm for vehicle control offers many advantages over traditional use of mechanical steering systems but comes at the cost of loss of proprioception (“road feel”). To this end, haptic interfaces for SBW systems have been proposed to restore the intimacy of interactive control back to the driver. However, the degree of realism for the interaction is dependent on the fidelity of the underlying computational vehicle dynamics model. Hence we focus on quantitative comparative testing of the role of vehicle dynamics modeling fidelity for haptic SBW tasks. Additionally the SBW paradigm can simplify implementation of shared/collaborative control (steering) of the underlying mechanical system (vehicle). Possibilities range from sharing of control between multiple individual users or between user and automation technology. Performance evaluation of 3 modes of shared control vs. individual control of driving was carried out and preliminary analysis of results is presented in the paper.Copyright © 2007 by ASME

In this paper, we evaluate the performance of two candidate formulations for distributed motion planning of robot collectives within an Artificial Potential Field (APF) framework. We exploit the parallel between the formulation of motion planning for group of robots coupled by constraints and the forward dynamics simulation of constrained multibody systems to develop the candidate approaches. We compare and contrast these approaches on the basis of ease of formulation, distribution of computation and overall computational accuracy. Traditionally penalty formulations have enjoyed a prominent position in motion planning of robot collectives due to their ease of formulation, decentralization and scalability. However, the instabilities introduced in the form of “formulation stiffness” at the algorithm development stage have the potential to hinder the subsequent control. Representative results from the distributed motion planning for a group of 3 point-mass robots moving in formation to a desired target location are used to highlight the differences.

Rehabilitation is a complex multifaceted process with complexity and variability that depends not only on human patients and/or specialized equipment but also on the nature of their functional interaction. Rapid and effective customization of the functional interactions between the patient and the rehabilitation device thus becomes critical for any rehabilitation program. Two principal dimensions govern the effectiveness of such functional interactions: geometric placement of user-device (ergonomics) and exercise selection and performance (regimen). In this paper, we discuss aspects of creation of a virtual design environment, leveraging tools from musculoskeletal analysis, optimization, and simulation-based design, which will permit a therapist to rapidly evaluate and systematically customize various candidate rehabilitation programs. Specifically, this framework: (i) permits study of parametric performance variability due to ergonomic or regimen variability; and (ii) facilitates use of all design tools such as optimization to determine the best program. We illustrate various aspects of this customization using an illustrative case-study of a motor-rehabilitation haptic virtual driving environment

By permitting designers to realistically, accurately and quantitatively prototype and test multiple intermediate models within virtual environment, Virtual Prototyping (VP), also known as Simulation-Based Design (SBD), has rapidly gained popularity and become a crucial part of most engineering design processes. While there is a significant demand from industry for students trained in this methodology, currently there is not much room in engineering curriculum to permit widespread adoption in the lecture-based classroom. In this paper, we describe the rationale and the stages in the development of a series of web-based and self-paced VP tutorials targeted at students of a course in machine and mechanism design. These undergraduate seniors are permitted to: (1) interactively explore the process of creating engineering analysis models in integrated VP environment; (2) develop skills for interactive SBD of models; and (3) develop their engineering judgment by interactive exploration of a spectrum of examples. The outcome of a phased introduction of these exercises and our experience based on the first successful course offering are also discussed.Copyright © 2003 by ASME

It is revealed in the present paper that the reflectance around the defect mode of one-dimensional defective photonic crystal (PC) in an asymmetric structure approaches to 1, while the phase-shift depends on the number of the coupled-defect layers, i.e., the phase shift is 2π for every sub-peak of the defect mode. When the defect layer is a temperature sensitive material, very small change of temperature will cause a significant phase change. Secondly, it is demonstrated that the relationship of phase and temperature has a linear range. According to the above characteristics, a highly sensitive temperature sensor is designed based on the phase property of photonic crystal. Moreover, this principle of PC phase sensing can be extended to study other sensors, such as the two-dimensional PC, which is suitable for optical integration.