scholarly journals STRUCTURAL AND METABOLIC CHARACTERIZATION OF THE MUSCLES USED TO POWER RUNNING IN THE EMU (DROMAIUS NOVAEHOLLANDIAE), A GIANT FLIGHTLESS BIRD

1993 ◽  
Vol 175 (1) ◽  
pp. 233-249 ◽  
Author(s):  
A. Patak ◽  
J. Baldwin
Keyword(s):  
High Speed ◽  
High Energy ◽  
Lower Leg ◽  
Creatine Kinase Activity ◽  
Muscle Fibres ◽  
Endurance Running ◽  
Major Power ◽  
Total Body Mass ◽  
Leg Muscles ◽  
Lift Off

The emu is a giant flightless bird, capable of sustained high-speed running. Anatomical, histochemical and biochemical properties of the lower leg muscles used to power running were investigated. The gastrocnemius is the largest muscle in the emu leg. It has a short inelastic tendon and contains only fast fibres. It is the major power-producing muscle of the lower leg, with a greater capacity than the digital flexor muscles for bursts of high work output. In marked contrast, the digital flexors have long elastic tendons and contain both fast and slow muscle fibres. It is proposed that these muscles, rather than the gastrocnemius, are responsible for maintaining posture and that they facilitate elastic energy storage and retrieval in their tendons during running. In comparison with equivalent muscles of flying and diving birds, emu lower leg muscles display features consistent with greater power output during both short burst and endurance running. The emu muscles are more massive relative to body size, and the gastrocnemii of other birds invariably contain slow fibres This study illustrates some of the similarities as well as differences between muscles used during flying and running. Capacities for sustained high-energy work appear to be similar in flying birds and running emus as judged from (1) the muscle masses used during locomotion when expressed as a proportion of total body mass and (2) muscle fibre type compositions and their potential for fuel catabolism. The lower creatine kinase activity in emu leg muscles could be attributed to higher energy demands during the initial stages of lift-off for flight.

Histochemical properties of locomotory muscles of European hares and cottontail rabbits

1984 ◽  
Vol 62 (11) ◽  
pp. 2157-2163 ◽  
Author(s):  
D. L. Schnurr ◽  
V. G. Thomas
Keyword(s):  
High Speed ◽  
Succinic Dehydrogenase ◽  
Oxidative Capacity ◽  
Muscle Fibres ◽  
Sylvilagus Floridanus ◽  
Endurance Running ◽  
Locomotor Muscles ◽  
Transverse Area ◽  
Lepus Capensis ◽  
Fast Twitch

European hares (Lepus capensis) and cottontail rabbits (Sylvilagus floridanus) represent near extremes in the locomotory pattern encountered among leporids. Animals of both species were collected and four major hindlimb locomotor muscles were examined histochemically for succinic dehydrogenase and myosin adenosine triphosphatase activities. Muscle fibres were classified as fast-twitch glycolytic, fast-twitch oxidative glycolytic, or slow-twitch oxidative, and the percent composition and transverse area of the fibre types were obtained. Hare muscles had a much greater oxidative capacity than cottontail muscles as shown by 32–55% more fast-twitch oxidative glycolytic fibres than cottontail muscles. This correlates with the capacity of hares for high-speed endurance running and their inhabiting open, expansive environments. Cottontail muscles had a large proportion (45–54%) of fast-twitch glycolytic fibres of large transverse area resulting in the muscles being composed primarily of fast-twitch glycolytic fibres. This reflects the capacity of rabbits for quick bursts of activity and this type of locomotor pattern may restrict cottontails to densely covered deciduous habitats.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

scholarly journals 1.5 °C degrowth scenarios suggest the need for new mitigation pathways

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lorenz T. Keyßer ◽  
Manfred Lenzen
Keyword(s):  
Technological Change ◽  
High Speed ◽  
Large Scale ◽  
High Energy ◽  
Climate Mitigation ◽  
Intergovernmental Panel ◽  
Economic Output ◽  
Integrated Assessment Modelling ◽  
Negative Emissions ◽  
Energy Emissions

Abstract1.5  °C scenarios reported by the Intergovernmental Panel on Climate Change (IPCC) rely on combinations of controversial negative emissions and unprecedented technological change, while assuming continued growth in gross domestic product (GDP). Thus far, the integrated assessment modelling community and the IPCC have neglected to consider degrowth scenarios, where economic output declines due to stringent climate mitigation. Hence, their potential to avoid reliance on negative emissions and speculative rates of technological change remains unexplored. As a first step to address this gap, this paper compares 1.5  °C degrowth scenarios with IPCC archetype scenarios, using a simplified quantitative representation of the fuel-energy-emissions nexus. Here we find that the degrowth scenarios minimize many key risks for feasibility and sustainability compared to technology-driven pathways, such as the reliance on high energy-GDP decoupling, large-scale carbon dioxide removal and large-scale and high-speed renewable energy transformation. However, substantial challenges remain regarding political feasibility. Nevertheless, degrowth pathways should be thoroughly considered.

Asymmetrical Neural Adaptation in Lower Leg Muscles as a Consequence of Stereotypical Motor Training

2012 ◽  
Vol 44 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Tetsuya Ogawa ◽  
Noritaka Kawashima ◽  
Shuji Suzuki ◽  
Kimitaka Nakazawa
Keyword(s):  
Lower Leg ◽  
Neural Adaptation ◽  
Motor Training ◽  
Leg Muscles

Detector commissioning and development for PETRA-III

2010 ◽  
Vol 1 (SRMS-7) ◽  
Author(s):  
David Pennicard ◽  
Heinz Graafsma ◽  
Michael Lohmann
Keyword(s):  
High Speed ◽  
Materials Science ◽  
Dynamic Range ◽  
Photon Counting ◽  
High Energy ◽  
X Rays ◽  
Silicon Detectors ◽  
Time Resolved ◽  
Wide Range ◽  
Synchrotron Light

The new synchrotron light source PETRA-III produced its first beam last year. The extremely high brilliance of PETRA-III and the large energy range of many of its beamlines make it useful for a wide range of experiments, particularly in materials science. The detectors at PETRA-III will need to meet several requirements, such as operation across a wide dynamic range, high-speed readout and good quantum efficiency even at high photon energies. PETRA-III beamlines with lower photon energies will typically be equipped with photon-counting silicon detectors for two-dimensional detection and silicon drift detectors for spectroscopy and higher-energy beamlines will use scintillators coupled to cameras or photomultiplier tubes. Longer-term developments include ‘high-Z’ semiconductors for detecting high-energy X-rays, photon-counting readout chips with smaller pixels and higher frame rates and pixellated avalanche photodiodes for time-resolved experiments.

High Speed Imaging of Forced Ignition Kernels in Non-Uniform Jet Fuel/Air Mixtures

2017 ◽  
Author(s):  
Sheng Wei ◽  
Brandon Sforzo ◽  
Jerry Seitzman
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Air Flow ◽  
Cetane Number ◽  
High Energy ◽  
Liquid Fuels ◽  
High Speed Imaging ◽  
Ignition Probability ◽  
Turbine Engine ◽  
Planar Laser

This paper describes experimental measurements of forced ignition of prevaporized liquid fuels in a well-controlled facility that incorporates non-uniform flow conditions similar to those of gas turbine engine combustors. The goal here is to elucidate the processes by which the initially unfueled kernel evolves into a self-sustained flame. Three fuels are examined: a conventional Jet-A and two synthesized fuels that are used to explore fuel composition effects. A commercial, high-energy recessed cavity discharge igniter located at the test section wall ejects kernels at 15 Hz into a preheated, striated crossflow. Next to the igniter wall is an unfueled air flow; above this is a premixed, prevaporized, fuel-air flow, with a matched velocity and an equivalence ratio near 0.75. The fuels are prevaporized in order to isolate chemical effects. Differences in early ignition kernel development are explored using three, synchronized, high-speed imaging diagnostics: schlieren, emission/chemiluminescence, and OH planar laser-induced fluorescence (PLIF). The schlieren images reveal rapid entrainment of crossflow fluid into the kernel. The PLIF and emission images suggest chemical reactions between the hot kernel and the entrained fuel-air mixture start within tens of microseconds after the kernel begins entraining fuel, with some heat release possibly occurring. Initially, dilution cooling of the kernel appears to outweigh whatever heat release occurs; so whether the kernel leads to successful ignition or not, the reaction rate and the spatial extent of the reacting region decrease significantly with time. During a successful ignition event, small regions of the reacting kernel survive this dilution and are able to transition into a self-sustained flame after ∼1–2 ms. The low aromatic/low cetane number fuel, which also has the lowest ignition probability, takes much longer for the reaction zone to grow after the initial decay. The high aromatic, more easily ignited fuel, shows the largest reaction region at early times.

Long-Lasting Changes in Muscle Twitch Force During Simulated Work While Standing or Walking

2016 ◽  
Vol 58 (8) ◽  
pp. 1117-1127 ◽  
Author(s):  
Maria-Gabriela Garcia ◽  
Rudolf Wall ◽  
Benjamin Steinhilber ◽  
Thomas Läubli ◽  
Bernard J. Martin
Keyword(s):  
Muscle Function ◽  
Signal Amplitude ◽  
Lower Leg ◽  
Muscle Twitch ◽  
Prolonged Standing ◽  
Twitch Force ◽  
Slow Pace ◽  
Leg Muscles ◽  
Ergonomic Interventions ◽  
Hard Floor

Objective: The aim of this study was to evaluate the long-lasting effects of prolonged standing work on a hard floor or floor mat and slow-pace walking on muscle twitch force (MTF) elicited by electrical stimulation. Background: Prolonged standing work may alter lower-leg muscle function, which can be quantified by changes in the MTF amplitude and duration related to muscle fatigue. Ergonomic interventions have been proposed to mitigate fatigue and discomfort; however, their influences remain controversial. Method: Ten men and eight women simulated standing work in 320-min experiments with three conditions: standing on a hard floor or an antifatigue mat and walking on a treadmill, each including three seated rest breaks. MTF in the gastrocnemius-soleus muscles was evaluated through changes in signal amplitude and duration. Results: The significant decrease of MTF amplitude and an increase of duration after standing work on a hard floor and on a mat persisted beyond 1 hr postwork. During walking, significant MTF metrics changes appeared 30 min postwork. MTF amplitude decrease was not significant after the first 110 min in any of the conditions; however, MTF duration was significantly higher than baseline in the standing conditions. Conclusion: Similar long-lasting weakening of MTF was induced by standing on a hard floor and on an antifatigue mat. However, walking partially attenuated this phenomenon. Application: Mostly static standing is likely to contribute to alterations of MTF in lower-leg muscles and potentially to musculoskeletal disorders regardless of the flooring characteristics. Occupational activities including slow-pace walking may reduce such deterioration in muscle function.

scholarly journals Comparison of physical and qualitative traits of meat of two Polish conservative flocks of ducks

2004 ◽  
Vol 47 (4) ◽  
pp. 367-375 ◽  
Author(s):  
T. Kisiel ◽  
J. M. Książkiewicz
Keyword(s):  
Subcutaneous Fat ◽  
Biceps Femoris ◽  
Point Of View ◽  
Muscle Fibres ◽  
Mean Values ◽  
Qualitative Traits ◽  
Biceps Femoris Muscle ◽  
Leg Muscles ◽  
L Value ◽  
Femoris Muscle

Abstract. In two Polish conservative flocks of Miniduck (K2) and Pekin (P33), registered by FAO as domestic genetic resources (World Watch List, 2000) the mean values of physical (tissue components) and qualitative traits of meat (pH15, pH24, colour of meat) were determined. The experimental flocks showed significant variations in body weight at 7 weeks of age (1540 vs 2088 in drakes and 1395 vs 1986 g in ducks), in the proportion of breast and leg muscles and skin with subcutaneous fat in eviscerated carcass. K2 ducks are characterized by outstanding musculature of breast and P33 ducks by that of lower leg and by low fatness. pH15 values of breast and leg muscles in K2 and P33 birds were greater than pH24 of these muscles. In both flocks pH15 values of 6.09 to 6.33 and pH24 values of 5.90 to 6.05 in breast muscles were lower than in leg muscles (6.33 to 6.46 and 6.12 to 6.37, respectively). A significantly lower L* value (darker colour) of breast muscle was characteristic of K2 birds (43.7 in males and 40.5 in females) compared to P33 males and females. Furthermore, breast muscles of K2 drakes and ducks had significantly higher redness (a*) and yellowness values (b*) than P33. In pectoralis superficialis muscle of K2 and P33 females, a significantly lower diameter was found for white muscle fibres (αW) (30.0 to 30.5 μm) and for red muscle fibres (βR) (16.9 to 17.6 μm) than in biceps femoris muscle (αW from 48.3 to 54.2; βR from 36.0 to 37.1 μm). Muscle fibres of K2 compared to P33 ducks were characterized by significantly greater diameters of βR muscle fibre in pectoralis superficialis muscle, and by lower αW and βR fibre diameters in biceps femoris muscle. The experiment showed that meat of ducks from the conservative flocks studied is valuable from the consumer’s point of view.

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