This paper introduces a new robust, dynamic quadruped, the MIT Cheetah 3. Like its predecessor, the Cheetah 3 exploits tailored mechanical design to enable simple control strategies for dynamic locomotion and features highbandwidth proprioceptive actuators to manage physical interaction with the environment. A new leg design is presented that includes proprioceptive actuation on the abduction/adduction degrees of freedom in addition to an expanded range of motion on the hips and knees. To make full use of these new capabilities, general balance and locomotion controllers for Cheetah 3 are presented. These controllers are embedded into a modular control architecture that allows the robot to handle unexpected terrain disturbances through reactive gait modification and without the need for external sensors or prior environment knowledge. The efficiency of the robot is demonstrated by a low Cost of Transport (CoT) over multiple gaits at moderate speeds, with the lowest CoT of 0.45 found during trotting. Experiments showcase the ability to blindly climb up stairs as a result of the full system integration. These results collectively represent a promising step toward a platform capable of generalized dynamic legged locomotion.

Cardiac complications and heart failure are the leading cause of death in type 2 diabetic patients. Mitochondrial dysfunction is central in the pathogenesis of the type 2 diabetic heart. However, it is unclear whether this dysfunction is specific for a particular subcellular region. The purpose of this study was to determine whether mitochondrial dysfunction in the type 2 diabetic heart is specific to a spatially distinct subset of mitochondria. We investigated mitochondrial morphology, function, and proteomic composition of subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM) in 18-wk-old db/db mice. Oxidative damage was assessed in subpopulations through the measurement of lipid peroxidation byproducts and nitrotyrosine residues. Proteomic profiles and posttranslational modifications were assessed in mitochondrial subpopulations using iTRAQ and multi-dimensional protein identification technologies, respectively. SSM from db/db hearts had altered morphology, including a decrease in size and internal complexity, whereas db/db IFM were increased in internal complexity. Db/db SSM displayed decreased state 3 respiration rates, electron transport chain activities, ATP synthase activities, and mitochondrial membrane potential and increased oxidative damage, with no change in IFM. Proteomic assessment revealed a greater impact on db/db SSM compared with db/db IFM. Inner mitochondrial membrane proteins, including electron transport chain, ATP synthesis, and mitochondrial protein import machinery, were predominantly decreased. We provide evidence that mitochondrial dysfunction in the type 2 diabetic heart is associated with a specific subcellular locale. Furthermore, mitochondrial morphological and functional indexes are impacted differently during type 2 diabetic insult and may result from the modulation of spatially distinct mitochondrial proteomes.

Diabetic cardiomyopathy is associated with increased risk of heart failure in type 1 diabetic patients. Mitochondrial dysfunction is suggested as an underlying contributor to diabetic cardiomyopathy. Cardiac mitochondria are characterized by subcellular spatial locale, including mitochondria located beneath the sarcolemma, subsarcolemmal mitochondria (SSM), and mitochondria situated between the myofibrils, interfibrillar mitochondria (IFM). The goal of this study was to determine whether type 1 diabetic insult in the heart influences proteomic make-up of spatially distinct mitochondrial subpopulations and to evaluate the role of nuclear encoded mitochondrial protein import. Utilizing multiple proteomic approaches (iTRAQ and two-dimensional-differential in-gel electrophoresis), IFM proteomic make-up was impacted by type 1 diabetes mellitus to a greater extent than SSM, as evidenced by decreased abundance of fatty acid oxidation and electron transport chain proteins. Mitochondrial phosphate carrier and adenine nucleotide translocator, as well as inner membrane translocases, were decreased in the diabetic IFM ( P < 0.05 for both). Mitofilin, a protein involved in cristae morphology, was diminished in the diabetic IFM ( P < 0.05). Posttranslational modifications, including oxidations and deamidations, were most prevalent in the diabetic IFM. Mitochondrial heat shock protein 70 (mtHsp70) was significantly decreased in diabetic IFM ( P < 0.05). Mitochondrial protein import was decreased in the diabetic IFM with no change in the diabetic SSM ( P < 0.05). Taken together, these results indicate that mitochondrial proteomic alterations in the type 1 diabetic heart are more pronounced in the IFM. Further, proteomic alterations are associated with nuclear encoded mitochondrial protein import dysfunction and loss of an essential mitochondrial protein import constituent, mtHsp70, implicating this process in the pathogenesis of the diabetic heart.

In December 2013, 16 teams from around the world gathered at Homestead Speedway near Miami, FL to participate in the DARPA Robotics Challenge (DRC) Trials, an aggressive robotics competition partly inspired by the aftermath of the Fukushima Daiichi reactor incident. While the focus of the DRC Trials is to advance robotics for use in austere and inhospitable environments, the objectives of the DRC are to progress the areas of supervised autonomy and mobile manipulation for everyday robotics. NASA's Johnson Space Center led a team comprised of numerous partners to develop Valkyrie, NASA's first bipedal humanoid robot. Valkyrie is a 44 degree‐of‐freedom, series elastic actuator‐based robot that draws upon over 18 years of humanoid robotics design heritage. Valkyrie's application intent is aimed at not only responding to events like Fukushima, but also advancing human spaceflight endeavors in extraterrestrial planetary settings. This paper presents a brief system overview, detailing Valkyrie's mechatronic subsystems, followed by a summarization of the inverse kinematics‐based walking algorithm employed at the Trials. Next, the software and control architectures are highlighted along with a description of the operator interface tools. Finally, some closing remarks are given about the competition, and a vision of future work is provided.

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Mitochondrial dysfunction is a contributor to diabetic cardiomyopathy. Previously, we observed proteomic decrements within the inner mitochondrial membrane (IMM) and matrix of diabetic cardiac interfibrillar mitochondria (IFM) correlating with dysfunctional mitochondrial protein import. The goal of this study was to determine whether overexpression of mitochondria phospholipid hydroperoxide glutathione peroxidase 4 (mPHGPx), an antioxidant enzyme capable of scavenging membrane-associated lipid peroxides in the IMM, could reverse proteomic alterations, dysfunctional protein import, and ultimately, mitochondrial dysfunction associated with the diabetic heart. MPHGPx transgenic mice and controls were made diabetic by multiple low-dose streptozotocin injections and examined after 5 wk of hyperglycemia. Five weeks after hyperglycemia onset, in vivo analysis of cardiac contractile function revealed decreased ejection fraction and fractional shortening in diabetic hearts that was reversed with mPHGPx overexpression. MPHGPx overexpression increased electron transport chain function while attenuating hydrogen peroxide production and lipid peroxidation in diabetic mPHGPx IFM. MPHGPx overexpression lessened proteomic loss observed in diabetic IFM. Posttranslational modifications, including oxidations and deamidations, were attenuated in diabetic IFM with mPHGPx overexpression. Mitochondrial protein import dysfunction in diabetic IFM was reversed with mPHGPx overexpression correlating with protein import constituent preservation. Ingenuity Pathway Analyses indicated that oxidative phosphorylation, tricarboxylic acid cycle, and fatty acid oxidation processes most influenced in diabetic IFM were preserved by mPHGPx overexpression. Specific mitochondrial networks preserved included complex I and II, mitochondrial ultrastructure, and mitochondrial protein import. These results indicate that mPHGPx overexpression can preserve the mitochondrial proteome and provide cardioprotective benefits to the diabetic heart.

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