Thesis (Ph. D.)--University of Wisconsin, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 232-237).

Thesis (M.Eng.)--Memorial University of Newfoundland, 1997. / Restricted until May 1998. Bibliography: leaves 148-152.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 74-75).

Thesis (M.S.)--University of British Columbia, 2003. / Includes bibliographical references (leaves 76-81).

Thesis (M.S.)--University of Oregon, 2003. / Includes bibliographical references (leaves 75-81).

Human locomotor economy and efficiency are highly variable. This study investigated the role that stature plays in this variation, by evaluating metabolic and respiratory responses to walking and running at speeds set relative to one's stature. Four groups of subjects: male, high V0₂ max (n = 11); male, average V0₂ max (n = 10); female, high V0₂ max (n = 10); and female, average V0₂ max (n = 11) were habituated to treadmill locomotion prior to the measurement of maximal oxygen consumption (V0₂ max). The V0₂ max test entailed 1 km.h⁻¹ increases per min from 3 to 6 km.h⁻¹ walking, and 7 - 17 km.h⁻¹ running then 1% grade increments per min until exhaustion. On each of four other occasions, the subject walked or ran at 6 of a variety of relative speeds - walking at 0.5, 0.7, 0.9, 1.1, 1.3; running at 1.5, 1.7, 1.9 and for selected subjects 2.1, 2.3 and 2.5 statures.s⁻¹ ,and grades - 0%, +3%, -3%. Steady-state respiratory and metabolic responses, and treadmill speed were monitored by an on-line computer system developed for this study. Cadence and RPE were also monitored. All subjects demonstrated an exponential relationship between V0₂ and walking relative speed (st.s⁻¹) (RS) . V0₂ (ml.kg⁻¹.min⁻¹ ) = 4.747 * e(1.371*RS) During running this relationship was essentially linear . The variability of economy at relative speed (9.08%) and absolute speed (9. 01%) did not differ. Male and female subjects did not differ in response to absolute speed but females were more economical at relative speeds (p<0.05). Those with high and average aerobic capacity did not differ in locomotor economy at relative speed. Higher freely-chosen stride length was associated with a higher V0₂ response as velocity increased. The V0₂ of uphill walking was 1.4 times greater than that for downhill walking (running: 1.28 times) . Stride length decreased with increasing speed in uphill locomotion but the reverse was the case for downhill. The economy and efficiency of walking was greater than that of running. Walking economy was maximal between 0.7 and 0.9 st. s⁻¹. Running economy remained essentially unaffected by increased velocity. The setting of locomotor velocity relative to stature does not minimize inter-subject variability in metabolic and respiratory response .

Orientador: Franco Giuseppe Dedini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-13T06:15:58Z (GMT). No. of bitstreams: 1 Silva_JoelFerreirada_M.pdf: 9536924 bytes, checksum: c20506c78c6b701b46bf63781f7fc0c6 (MD5) Previous issue date: 2009 / Resumo: O objetivo deste trabalho é propor um mecanismo alternativo para a superação de barreiras arquitetônicas do tipo rampas de até 8°. As cadeiras de rodas manuais convencionais exigem esforço muscular do usuário nos aros de propulsão, sendo muitas vezes um mecanismo ineficiente na superação destas barreiras arquitetônicas. Este mecanismo alternativo dotado de uma combinação de alavancas propulsoras e embreagem seletiva que permite o travamento das rodas traseiras da cadeira de rodas no avanço de superação de rampas e rodas livres no momento da propulsão convencional. Foi utilizado o ambiente de Working Model 3D® para a simulação da cadeira de rodas no momento da progressão da superação de rampas. A partir de uma revisão bibliográfica dos padrões de propulsão, desempenho e de mecanismos alternativos existentes, foi elaborada a proposta do presente mecanismo alternativo. / Abstract: This study aims to present a proposal of an alternative mechanism that is able to surpass architectural barriers like ramps with an inclination up to 8 degrees. The conventional manual wheelchair requires muscular effort from the user at rims of propulsion. Although this thousandyear- old mechanism of propulsion isn't efficient enough to surpass architectural barriers. This alternative mechanism, composed by a combination of propellers levers and selective clutch, allows the user to break the rear wheels when advancing ramps, and free wheels at the moment of conventional propulsion.For this study it was considered a Working Model 3D® environment to simulate the wheelchairs at the moment of progressive surpass of ramps. A bibliographical review envolving the binomial wheelchair - user, considering standards of propulsion, performance and existing alternative mechanisms, generated the proposal of this present alternative mechanism. / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

The stopping of an earlier intended action is best explained in a race between a go process and a stop process (Logan & Cowan, 1984). The finish line, to which each process races, has been likened to a point of no return, specifically one that marks the onset of a final ballistic (unstoppable) process. Of note is the typical relation of reduced go probabilities and faster go latencies at shorter signal onset asynchronies (SOAs). (The SOA is the time interval between presentation of the go signal and presentation of the stop signal.) We report, in some cases, sub-maximal surface electromyograms (EMGs) at onset when trying to stop a maximal speeded action. These data indicate reduced synaptic drive to reach the motor pools as a result of earlier stopping effects and, as such, hold important implications for a theory of control. First, we interpret these data to suggest that the point of no return is phantom. Sub-maximal EMGs indicate a point in the control stream beyond which some EMG will be later observed but, importantly, they fail to mark the onset of a final ballistic process if, once breached, the same process remains subject to further effects of stopping. The alternative interpretation, however, that of a final ballistic process that receives sub-maximal input which results in sub-maximal output (i.e., EMG onset) cannot be ruled out from these data. We used the Hoffmann (H) reflex to probe further the mechanism of control for stopping a voluntary action. The H-reflex, an involuntary reflex that is taken as an index of spinal control, is relevant to the control of stopping because it is typically facilitated a short time before EMG onset. In other words, it provides a window of control within which a final ballistic process would otherwise be expected to locate. Thus, we interpret the effects of stopping on the H-reflex before EMG onset as strong evidence against a final ballistic process. Second, while the race model can explain the relation between the go probabilities, the go latencies and the SOAs, it fails to explain the sub-maximal EMG onsets that describe that same action in some cases. We submit a mechanism of excitatory-inhibitory interaction at all times up to the motor pool to explain both sets of empirical data. The viability of this theory is demonstrated using computer analyses. / Education, Faculty of / Kinesiology, School of / Graduate

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