scholarly journals Can the Center of Mass Reflect the Metabolic Expenditure?

2010 ◽  
Vol 16 (1) ◽  
pp. 16-21
Author(s):  
Ying ki FUNG ◽  
Tyzz yuang SHIANG
Keyword(s):  
Pulmonary Ventilation ◽  
Center Of Mass ◽  
Metabolic Cost ◽  
The Past ◽  
Transition Speed ◽  
Wide Range ◽  
Locomotion Pattern ◽  
Metabolic Expenditure ◽  
Analysis System ◽  
Preferred Transition Speed

LANGUAGE NOTE | Document text in English; abstract also in Chinese. In the past studies, the movement of center or mass (COM) was one of the descriptor to estimate the metabolic expenditure. However, the sensitivity of this method among the wide range speed, the locomotion pattern and during the Energetically Optimal Transition Speed (EOTS) is still unexplored. Hence that, the purpose of this investigation was to determine the metabolic and COM pattern differences between walk and run among the EOTS with a reflective marker motion analysis system and indirect pulmonary ventilation machine. The results showed that there is a metabolic intersection on two locomotion patterns (walk and run) between 100 and 125% Preferred Transition Speed (PTS), which coincides with the past EOTS studies, whereas, COM result showed that the variation of vertical COM displacement for running is significantly higher than walking among the entire tested speed. The pattern between the metabolic and COM variables is an inverse relation after the EOTS. Hence, the present investigator doubted that there would be a reliability problem for those instruments which use the COM displacement to estimate the metabolic cost or the intensity of physical activity among 5.15 to 9.82km/h for walk and run. 在過去的研究，身體質量中心移動常常被用作評估身體耗能的一種方法。可是這種方法在不同速度、動作型態及最佳轉換速度(EOTS)之可信範圍一直都沒有作出深入探討。因此本研究目的希望利用動作及生理分析系統對身體中心及身體耗能在兩種動作型態(走和跑)和在EOTS的情況底下的趨勢上作出分析及探討。結果顯示在兩個動作型態上在100及125%自然轉換速度情況下身體耗能出現交叉點(EOTS)，而此發現與過去EOTS之文獻相吻合，反之身體質量中心結果顯示，跑步在身體質量中心之穩定性在所有測試速度情況下都比走路有統計上之差異，跑步的垂直位移變異量明顯比走路大。由此可見身體耗能及身體質量中心變異量顯示出兩者在EOTS出現後是反比關係。因此本研究結果可推斷現在有利用身體質量中心變異量去推估身體耗能或身體活動量的儀器在速度5.15—9.82公里的情況底下可能會出現信度問題。

scholarly journals Does the Preferred Walk-Run Transition Speed on Steep Inclines Minimize Energetic Cost, Heart Rate or Neither?

2021 ◽  
pp. jeb.233056
Author(s):  
Jackson W. Brill ◽  
Rodger Kram
Keyword(s):  
Heart Rate ◽  
Linear Regression ◽  
Energetic Cost ◽  
Regression Equations ◽  
Rate Data ◽  
Heart Rate Data ◽  
Transition Speed ◽  
Wide Range ◽  
Incremental Protocol ◽  
Preferred Transition Speed

Humans prefer to walk at slow speeds and to run at fast speeds. In between, there is a speed at which people choose to transition between gaits, the Preferred Transition Speed (PTS). At slow speeds, it is energetically cheaper to walk and at faster speeds, it is cheaper to run. Thus, there is an intermediate speed, the Energetically Optimal Transition Speed (EOTS). Our goals were to determine: 1) how PTS and EOTS compare across a wide range of inclines and 2) if the EOTS can be predicted by the heart rate optimal transition speed (HROTS). Ten healthy, high-caliber, male trail/mountain runners participated. On day 1, subjects completed 0° and 15° trials and on day 2, 5° and 10°. We calculated PTS as the average of the walk-to-run transition speed (WRTS) and the run-to-walk transition speed (RWTS) determined with an incremental protocol. We calculated EOTS and HROTS from energetic cost and heart rate data for walking and running near the expected EOTS for each incline. The intersection of the walking and running linear regression equations defined EOTS and HROTS. We found that PTS, EOTS, and HROTS all were slower on steeper inclines. PTS was slower than EOTS at 0°, 5°, and 10°, but the two converged at 15°. Across all inclines, PTS and EOTS were only moderately correlated. Although EOTS correlated with HROTS, EOTS was not predicted accurately by heart rate on an individual basis.

scholarly journals Evaluating the energetics of entrainment in a human–machine coupled oscillator system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryan T. Schroeder ◽  
James L. Croft ◽  
John E. A. Bertram
Keyword(s):  
Central Pattern Generators ◽  
Metabolic Cost ◽  
The Body ◽  
Vertical Force ◽  
Wide Range ◽  
Metabolic Expenditure ◽  
Pattern Generators ◽  
Positive Work ◽  
Phase Relationships

AbstractDuring locomotion, humans sometimes entrain (i.e. synchronize) their steps to external oscillations: e.g. swaying bridges, tandem walking, bouncy harnesses, vibrating treadmills, exoskeletons. Previous studies have discussed the role of nonlinear oscillators (e.g. central pattern generators) in facilitating entrainment. However, the energetics of such interactions are unknown. Given substantial evidence that humans prioritize economy during locomotion, we tested whether reduced metabolic expenditure is associated with human entrainment to vertical force oscillations, where frequency and amplitude were prescribed via a custom mechatronics system during walking. Although metabolic cost was not significantly reduced during entrainment, individuals expended less energy when the oscillation forces did net positive work on the body and roughly selected phase relationships that maximize positive work. It is possible that individuals use mechanical cues to infer energy cost and inform effective gait strategies. If so, an accurate prediction may rely on the relative stability of interactions with the environment. Our results suggest that entrainment occurs over a wide range of oscillation parameters, though not as a direct priority for minimizing metabolic cost. Instead, entrainment may act to stabilize interactions with the environment, thus increasing predictability for the effective implementation of internal models that guide energy minimization.

scholarly journals The Role of Entrainment in Human Walking: Energy Minimization in Oscillating Environments

2020 ◽  
Author(s):  
Ryan Schroeder ◽  
James Croft ◽  
John Bertram
Keyword(s):  
Energy Minimization ◽  
Central Pattern Generators ◽  
Metabolic Cost ◽  
Vertical Force ◽  
Effective Implementation ◽  
Wide Range ◽  
Metabolic Expenditure ◽  
Pattern Generators ◽  
Phase Relationships

Abstract During locomotion, humans often entrain (i.e. synchronize) their steps to external oscillations: e.g. swaying bridges, tandem walking, bouncy harnesses, vibrating treadmills, exoskeletons. Previous studies have discussed the role of nonlinear oscillators (e.g. central pattern generators) in facilitating entrainment. However, the underlying benefits of entrainment are unknown. Given substantial evidence that humans prioritize economy during locomotion, we tested whether reduced metabolic expenditure accompanies human entrainment to vertical force oscillations, where frequency and amplitude were prescribed via a custom mechatronics system during walking. Although metabolic cost was not significantly reduced during entrainment, individuals who experienced negative work from oscillations had a higher cost than those who experienced positive work, and subjects generally selected phase relationships indicating the latter. It is possible that individuals use mechanical cues to infer energy cost and inform effective gait strategies. If so, an accurate prediction may rely on the relative stability of interactions with the environment. Our results suggest that entrainment is preferred over a wide range of oscillation parameters, though not as a direct priority for minimizing metabolic cost. Instead, entrainment may act to stabilize interactions with the environment, thus increasing predictability for the effective implementation of internal models that guide energy minimization.

scholarly journals The comparison of EMG characteristics and metabolic cost between walking and running near preferred transition speed

2017 ◽  
Vol 12 (2) ◽  
pp. 16-00544-16-00544
Author(s):  
Ying-Ki FUNG ◽  
Ming-Sheng CHAN ◽  
Yin-Shin LEE ◽  
Tzyy-Yuang SHIANG
Keyword(s):  
Metabolic Cost ◽  
Transition Speed ◽  
Preferred Transition Speed

scholarly journals Does the Preferred Walk-Run Transition Speed on Inclines Minimize Energetic Cost, Heart Rate or Neither?

2020 ◽  
Author(s):  
Jackson W. Brill ◽  
Rodger Kram
Keyword(s):  
Heart Rate ◽  
Linear Regression ◽  
Energetic Cost ◽  
Regression Equations ◽  
Rate Data ◽  
Heart Rate Data ◽  
Transition Speed ◽  
Wide Range ◽  
Incremental Protocol ◽  
Preferred Transition Speed

ABSTRACTHumans prefer to walk at slow speeds and to run at fast speeds. In between, there is a speed at which people choose to transition between gaits, the Preferred Transition Speed (PTS). At slow speeds, it is energetically cheaper to walk and at faster speeds, it is cheaper to run. Thus, there is an intermediate speed, the Energetically Optimal Transition Speed (EOTS). Our goals were to determine: 1) how PTS and EOTS compare across a wide range of inclines and 2) if the EOTS can be predicted by the heart rate optimal transition speed (HROTS). Ten healthy, high-caliber, male trail/mountain runners participated. On day 1, subjects completed 0° and 15° trials and on day 2, 5° and 10°. We calculated PTS as the average of the walk-to-run transition speed (WRTS) and the run-to-walk transition speed (RWTS) determined with an incremental protocol. We calculated EOTS and HROTS from energetic cost and heart rate data for walking and running near the expected EOTS for each incline. The intersection of the walking and running linear regression equations defined EOTS and HROTS. We found that PTS, EOTS, and HROTS all were slower on steeper inclines. PTS was slower than EOTS at 0°, 5°, and 10°, but the two converged at 15°. PTS and EOTS were only moderately correlated. Although EOTS correlated with HROTS, EOTS was not predicted accurately by heart rate on an individual basis.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

Pursuit of the Abscopal Effect

2020 ◽  
Vol 04 (04) ◽  
pp. 369-372
Author(s):  
Paul B. Romesser ◽  
Christopher H. Crane
Keyword(s):  
Tumor Immunology ◽  
Antitumor Immunity ◽  
Clinical Success ◽  
Immune Recognition ◽  
Immune Modulators ◽  
Cancer Subtypes ◽  
The Past ◽  
Tumor Irradiation ◽  
Wide Range ◽  
Tumor Recognition

AbstractEvasion of immune recognition is a hallmark of cancer that facilitates tumorigenesis, maintenance, and progression. Systemic immune activation can incite tumor recognition and stimulate potent antitumor responses. While the concept of antitumor immunity is not new, there is renewed interest in tumor immunology given the clinical success of immune modulators in a wide range of cancer subtypes over the past decade. One particularly interesting, yet exceedingly rare phenomenon, is the abscopal response, characterized by a potent systemic antitumor response following localized tumor irradiation presumably attributed to reactivation of antitumor immunity.

The Many Pasts of Detective Fiction

2020 ◽  
Vol 1 (2) ◽  
pp. 157-172
Author(s):  
Thomas Leitch
Keyword(s):  
Detective Fiction ◽  
Golden Age ◽  
Public History ◽  
Detective Novel ◽  
Sherlock Holmes ◽  
Detective Story ◽  
The Past ◽  
Wide Range ◽  
Detective Novels ◽  
The Many

Building on Tzvetan Todorov's observation that the detective novel ‘contains not one but two stories: the story of the crime and the story of the investigation’, this essay argues that detective novels display a remarkably wide range of attitudes toward the several pasts they represent: the pasts of the crime, the community, the criminal, the detective, and public history. It traces a series of defining shifts in these attitudes through the evolution of five distinct subgenres of detective fiction: exploits of a Great Detective like Sherlock Holmes, Golden Age whodunits that pose as intellectual puzzles to be solved, hardboiled stories that invoke a distant past that the present both breaks with and echoes, police procedurals that unfold in an indefinitely extended present, and historical mysteries that nostalgically fetishize the past. It concludes with a brief consideration of genre readers’ own ambivalent phenomenological investment in the past, present, and future each detective story projects.

Nine Centuries of Man

2017 ◽  
Keyword(s):  
Twentieth Century ◽  
Diverse Range ◽  
Gender Expectations ◽  
Court Records ◽  
The Past ◽  
Wide Range ◽  
Police Reports ◽  
Late Twentieth ◽  
Scottish History ◽  
Late Twentieth Century

What did it mean to be a man in Scotland over the past nine centuries? Scotland, with its stereotypes of the kilted warrior and the industrial ‘hard man’, has long been characterised in masculine terms, but there has been little historical exploration of masculinity in a wider context. This interdisciplinary collection examines a diverse range of the multiple and changing forms of masculinities from the late eleventh to the late twentieth century, exploring the ways in which Scottish society through the ages defined expectations for men and their behaviour. How men reacted to those expectations is examined through sources such as documentary materials, medieval seals, romances, poetry, begging letters, police reports and court records, charity records, oral histories and personal correspondence. Focusing upon the wide range of activities and roles undertaken by men – work, fatherhood and play, violence and war, sex and commerce – the book also illustrates the range of masculinities that affected or were internalised by men. Together, the chapters illustrate some of the ways Scotland’s gender expectations have changed over the centuries and how, more generally, masculinities have informed the path of Scottish history

Free but fragile: Human relations amidst poverty and HIV in democratic South Africa

2015 ◽  
Vol 2 (2) ◽  
pp. 85-94
Author(s):  
Christina Landman
Keyword(s):  
South Africa ◽  
Predominantly White ◽  
Black People ◽  
Hiv Treatment ◽  
Human Relations ◽  
White People ◽  
Black And White ◽  
The Past ◽  
Wide Range ◽  
Black Township

Dullstroom-Emnotweni is the highest town in South Africa. Cold and misty, it is situated in the eastern Highveld, halfway between the capital Pretoria/Tswane and the Mozambique border. Alongside the main road of the white town, 27 restaurants provide entertainment to tourists on their way to Mozambique or the Kruger National Park. The inhabitants of the black township, Sakhelwe, are remnants of the Southern Ndebele who have lost their land a century ago in wars against the whites. They are mainly dependent on employment as cleaners and waitresses in the still predominantly white town. Three white people from the white town and three black people from the township have been interviewed on their views whether democracy has brought changes to this society during the past 20 years. Answers cover a wide range of views. Gratitude is expressed that women are now safer and HIV treatment available. However, unemployment and poverty persist in a community that nevertheless shows resilience and feeds on hope. While the first part of this article relates the interviews, the final part identifies from them the discourses that keep the black and white communities from forming a group identity that is based on equality and human dignity as the values of democracy.

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