Knee design for a bipedal walking robot based on a passive-dynamic walker

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 30).Passive-dynamic walkers are a class of robots that can walk down a ramp stably without actuators or control due to the mechanical dynamics of the robot. Using a passive-dynamic design as the basis for a powered robot helps to simplify the control problem and maximize energy efficiency compared to the traditional joint-angle control strategy. This thesis outlines the design of a knee for the robot known as Toddler, a passive-dynamic based powered walker built at the Massachusetts Institute of Technology. An actuator at the knee allows the robot to bend and straighten the leg, but a clutch mechanism allows the actuator to completely disengage so that the leg can swing freely. The clutch operates by using a motor to rotate a lead screw which engages or disengages a set of spur gears. Control of the knee is accomplished by utilizing the robot's sensors to determine whether or not the knee should be engaged. The engagement signal is then fed through a simple motor control circuit which controls the motor that turns the lead screw. The knee design was successfully implemented on Toddler but more work is required in order to optimize his walking. In order to study the dynamics of walking with knees, we also built a copy of McGeer's original passive walker with knees.by Andrew Griffin Baines.S.B

An archaeology of Iron Age domestic settlement in northern Scotland

No abstract availabl

Asymmetry in Leader Image Effects and the Implications for Leadership Positioning in the 2010 British General Election

Using national survey data on voters' perceptions of party leaders during the 2010 British general election campaign, we use logistic regression analysis to explore the association between specific image attributes and overall satisfaction for each leader. We find attribute-satisfaction relationships differ in some respects between the three main party leaders, demonstrating that leader image effects are not symmetrical across leaders. We find evidence that negative perceptions have more powerful effects on satisfaction than positive ones, implying that parties should seek to determine a leader's image attribute perceptions measured against the public's expectations of them on the same dimensions. The positions that campaigners ought then to choose are those that will have the most beneficial effect in encouraging voting behaviour for each particular leader or discouraging voting behaviour for an opponent

Does having a school-based wellbeing dog influence children’s socio-emotional development and learning? A thematic analysis of parent perspectives

This qualitative study explores the influence of having a ‘newly acquired’ school-based wellbeing dog on children’s socio-emotional development and learning, as reported by seven parents of children at a participating school. Results revealed three superordinate themes: Social Communication; Management of Emotions; and Attendance and Engagement. Parents held positive views towards the newly acquired wellbeing dog, especially regarding its role in their child’s socio-emotional development as well as their school engagement. The findings add to sparse literature, advocating for a wider distribution of wellbeing dogs in mainstream schools to support the mental health and wellbeing of children

Pumilio binds para mRNA and requires nanos and brat to regulate sodium current in drosophila motoneurons

Homeostatic regulation of ionic currents is of paramount importance during periods of synaptic growth or remodeling. Our previous work has identified the translational repressor Pumilio (Pum) as a regulator of sodium current (INa) and excitability in Drosophila motoneurons. In this current study, we show that Pum is able to bind directly the mRNA encoding the Drosophila voltage-gated sodium channel paralytic (para). We identify a putative binding site for Pum in the 3' end of the para open reading frame (ORF). Characterization of the mechanism of action of Pum, using whole-cell patch clamp and real-time reverse transcription-PCR, reveals that the full-length protein is required for translational repression of para mRNA. Additionally, the cofactor Nanos is essential for Pum-dependent para repression, whereas the requirement for Brain Tumor (Brat) is cell type specific. Thus, Pum-dependent regulation of INa in motoneurons requires both Nanos and Brat, whereas regulation in other neuronal types seemingly requires only Nanos but not Brat. We also show that Pum is able to reduce the level of nanos mRNA and as such identify a potential negative-feedback mechanism to protect neurons from overactivity of Pum. Finally, we show coupling between INa (para) and IK (Shal) such that Pum-mediated change in para results in a compensatory change in Shal. The identification of para as a direct target of Pum represents the first ion channel to be translationally regulated by this repressor and the location of the binding motif is the first example in an ORF rather than in the canonical 3'-untranslated region of target transcripts

Evaluating the long-term storage of Cryphonectria parasitica

Isolates of the Chestnut blight pathogen, Cryphonectria parasitica, from six populations in Michigan, were stored in the late 1990s as agar plugs of mycelium in vials of sterile water held at room temperature. Approximately 29% of the fungal isolates were infected with mycoviruses at the time of storage. Each isolate was tested for revivification effectiveness by taking aliquots from vials filled with agar plugs of C. parasitica and sterile water and plating onto potato dextrose agar. Average revivification success was 70.5% across populations with a range of 33—84% within populations. In situations where vials had dried out during storage, success was low (4%), while success for vials that retained sterile water averaged 90%. Most importantly however, is the loss of mycoviruses from stored isolates; only 2 of 119 stored mycovirus infected isolates still contained mycoviruses after storage, suggesting that the double-stranded RNA mycoviruses are degraded during storage

A moving grid finite element method applied to a model biological pattern generator

Many problems in biology involve growth. In numerical simulations it can therefore be very convenient to employ a moving computational grid on a continuously deforming domain. In this paper we present a novel application of the moving grid finite element method to compute solutions of reaction–diffusion systems in two-dimensional continuously deforming Euclidean domains. A numerical software package has been developed as a result of this research that is capable of solving generalised Turing models for morphogenesis

Optical mapping and optogenetics in cardiac electrophysiology research and therapy:a state-of-the-art review

State-of-the-art innovations in optical cardiac electrophysiology are significantly enhancing cardiac research. A potential leap into patient care is now on the horizon. Optical mapping, using fluorescent probes and high-speed cameras, offers detailed insights into cardiac activity and arrhythmias by analysing electrical signals, calcium dynamics, and metabolism. Optogenetics utilizes light-sensitive ion channels and pumps to realize contactless, cell-selective cardiac actuation for modelling arrhythmia, restoring sinus rhythm, and probing complex cell–cell interactions. The merging of optogenetics and optical mapping techniques for ‘all-optical’ electrophysiology marks a significant step forward. This combination allows for the contactless actuation and sensing of cardiac electrophysiology, offering unprecedented spatial–temporal resolution and control. Recent studies have performed all-optical imaging ex vivo and achieved reliable optogenetic pacing in vivo, narrowing the gap for clinical use. Progress in optical electrophysiology continues at pace. Advances in motion tracking methods are removing the necessity of motion uncoupling, a key limitation of optical mapping. Innovations in optoelectronics, including miniaturized, biocompatible illumination and circuitry, are enabling the creation of implantable cardiac pacemakers and defibrillators with optoelectrical closed-loop systems. Computational modelling and machine learning are emerging as pivotal tools in enhancing optical techniques, offering new avenues for analysing complex data and optimizing therapeutic strategies. However, key challenges remain including opsin delivery, real-time data processing, longevity, and chronic effects of optoelectronic devices. This review provides a comprehensive overview of recent advances in optical mapping and optogenetics and outlines the promising future of optics in reshaping cardiac electrophysiology and therapeutic strategies

Reconstructing glacial outburst floods (jökulhlaups) from geomorphology: challenges, solutions, and an enhanced interpretive framework

Glacial outburst floods (jökulhlaups) have been significant drivers of landscape change across Earth throughout the Quaternary and are a contemporary hazard in Arctic and alpine regions worldwide. Geomorphologic evidence is a foundation for reconstructing past and contemporary flood events and using additional analytical methods such as geochronology and paleohydraulics. Yet, accurate interpretation of jökulhlaup landforms and depositional sequences poses a persistent challenge due to complex controls on flood hydraulics and landscape evolution. Researchers have developed numerous strategies to reduce or resolve these challenges, but a comprehensive, globally applicable model to interpret flood evidence outside of sedimentary environments is lacking. This article synthesizes existing case studies to describe jökulhlaup geomorphologic interpretive challenges, discuss strategies to resolve them, and present a conceptual model of flood landform assemblages to illustrate hydraulic and environmental controls on resultant geomorphologic impacts. This enhanced interpretive framework aids researchers in identifying, interpreting, and testing geomorphologic evidence to reconstruct past jökulhlaups and predict future flood impacts as robustly as possible at a global, landscape-wide scale. Understanding jökulhlaup geomorphology yields insight into glacial lake and ice margin dynamics, the role of extreme events in landscape evolution, and interactions between climate, ice sheets, and hydrology. Moreover, it is increasingly important as glacial outburst floods may become more frequent due to climate-driven ice retreat, advancing predictive capacities to mitigate societal risk downstream.</div

Meningococcal disease in children in Merseyside, England:a 31 year descriptive study

Meningococcal disease (MCD) is the leading infectious cause of death in early childhood in the United Kingdom, making it a public health priority. MCD most commonly presents as meningococcal meningitis (MM), septicaemia (MS), or as a combination of the two syndromes (MM/MS). We describe the changing epidemiology and clinical presentation of MCD, and explore associations with socioeconomic status and other risk factors. A hospital-based study of children admitted to a tertiary children's centre, Alder Hey Children's Foundation Trust, with MCD, was undertaken between 1977 to 2007 (n = 1157). Demographics, clinical presentations, microbiological confirmation and measures of deprivation were described. The majority of cases occurred in the 1-4 year age group and there was a dramatic fall in serogroup C cases observed with the introduction of the meningococcal C conjugate (MCC) vaccine. The proportion of MS cases increased over the study period, from 11% in the first quarter to 35% in the final quarter. Presentation with MS (compared to MM) and serogroup C disease (compared to serogroup B) were demonstrated to be independent risk factors for mortality, with odds ratios of 3.5 (95% CI 1.18 to 10.08) and 2.18 (95% CI 1.26 to 3.80) respectively. Cases admitted to Alder Hey were from a relatively more deprived population (mean Townsend score 1.25, 95% CI 1.09 to 1.41) than the Merseyside reference population. Our findings represent one of the largest single-centre studies of MCD. The presentation of MS is confirmed to be a risk factor of mortality from MCD. Our study supports the association between social deprivation and MCD