66,882 research outputs found
Human muscle fascicle behavior in agonist and antagonist isometric contractions
No full textIntroduction: The aim of this study was to compare, at a given level of electromyographic (EMG) activity, the behavior of dorsiflexor and plantarflexor muscles as assessed via their architecture (pennation angle and fiber length) during agonist or antagonist isometric contractions. Methods: Realtime ultrasonography and EMG activity of gastrocnemius medialis (GM) and tibialis anterior (TA) muscles were obtained while young males performed ramp isometric contractions in dorsiand plantarflexion. Results: For both muscles, at a similar level of EMG activity, fiber length was longer, and pennation angle was smaller, during antagonist than during agonist contractions. Conclusions: These results indicate that, at similar levels of EMG activity, GM and TA muscles elicit a higher mechanical output while acting as an antagonist. These findings have important implications for muscle function testing. They show that estimation of antagonistic force using the common method based on the EMG/net torque relationship yields underestimated values
Mining e-mail content for author identification forensics
No full textWe describe an investigation into e-mail content mining for author identification, or authorship attribution, for the purpose of forensic investigation. We focus our discussion on the ability to discriminate between authors for the case of both aggregated e-mail topics as well as across different email topics. An extended set of e-mail document features including structural characteristics and linguistic patterns were derived and, together with a Support Vector Machine learning algorithm, were used for mining the e-mail content. Experiments using a number of e-mail documents generated by different authors on a set of topics gave promising results for both aggregated and multi-topic author categorisation
Training-induced changes in structural and mechanical properties of the patellar tendon are related to muscle hypertrophy but not to strength gains
No full textTo obtain a better understanding of the adaptations of human tendon to chronic overloading, we examined the relationships between these adaptations and the changes in muscle structure and function. Fifteen healthy male subjects (20 ± 2 yr) underwent 9 wk of knee extension resistance training. Patellar tendon stiffness and modulus were assessed with ultrasonography, and cross-sectional area (CSA) was determined along the entire length of the tendon by using magnetic resonance imaging. In the quadriceps muscles, architecture and volume measurements were combined to obtain physiological CSA (PCSA), and maximal isometric force was recorded. Following training, muscle force and PCSA increased by 31% (P < 0.0001) and 7% (P < 0.01), respectively. Tendon CSA increased regionally at 20-30%, 60%, and 90-100% of tendon length (5-6%; P < 0.05), and tendon stiffness and modulus increased by 24% (P < 0.001) and 20% (P < 0.01), respectively. Although none of the tendon adaptations were related to strength gains, we observed a positive correlation between the increase in quadriceps PCSA and the increases in tendon stiffness (r = 0.68; P < 0.01) and modulus (r = 0.75; P < 0.01). Unexpectedly, the increase in muscle PCSA was inversely related to the distal and the mean increases in tendon CSA (in both cases, r = -0.64; P < 0.05). These data suggest that, following short-term resistance training, changes in tendon mechanical and material properties are more closely related to the overall loading history and that tendon hypertrophy is driven by other mechanisms than those eliciting tendon stiffening. Copyright © 2009 the American Physiological Society
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Comparison between whole body vibration and static resistance training in postmenopausal women : long-term effects on quadriceps muscle volume and power
No full textIntroduction. Reductions in muscle mass, force and peak power occurring with aging markedly affect the quality of life of elderly people, particularly regarding the performance of daily activities such as walking, stair negotiation and standing up. However, resistance training has been shown to play a useful role in counteracting these impairments. Recently, Whole Body Vibration (WBV) exercise has been promoted as an alternative and feasible method to enhance strength and muscle performance. Although WBV seems to acutely increase muscle strength and power, its long-term efficacy on muscle structural and functional properties is still controversial and strictly controlled studies are lacking in literature (Rehn et al. 2007). Whether WBV is effective in combating sarcopenia and muscle weakness in old age is thus unknown.
Aim of the study. The aim of this research was to compare the long-term effects of a pure vibration training regime with an exercise protocol based on the same type of resistance training without vibration in order to identify the possible differences due to the vibration itself. Because elderly women are known to be at greater risk of losing functional independence than elderly men (Skelton et al. 1994), this study was performed in a population of post-menopausal women.
Material and methods. Eleven postmenopausal, recreationally active women, were assigned either to a vibration training group (VT, n=7, mean ± S.D: age 67.7±6.3 years, BMI 23.2±2) or to a control training group (CT, n=4, mean ± S.D: age 68.2±8.8 years, BMI 30.7±5.6). The VT underwent static isometric training on a vibration platform (Galileo Fitness ©, Novotec Maschinen GmbH, Germany) 3 times per week for 8 weeks. Each session consisted of four sets of ten isometric semi-squats lasting ten seconds (80° of knee flexion) on the vibration platform at 30 Hz (amplitude: 0–5.2 mm), with ten seconds rest off the platform between each repetition. The CT undertook the same protocol but without vibration. During the workout all participants wore a weighted vest corresponding to 60% of one repetition maximum (1 RM), assessed weekly with a leg extension machine, in order to increase the intensity of the exercise. Quadriceps muscle volume (MV) assessed by magnetic resonance imaging, relative peak power (RP), peak power per muscle volume (PV) and height (JH) assessed during counter-movement jumps performed on a force platform (Leonardo ©, Novotec Medical, Pforzheim, Germany), were measured before and after the training periods.
Results. Between pre- and post-training VT and CT showed a non significant increase in MV by 3.3 and 4.9%, and in RP by 3.9 and 3.8% respectively (p>0.05). PV did not change in VT and slightly decreased (-2%) in CT in a non significant manner (p>0.05). JH did not show any change. Furthermore, no significant differences were found between the two training groups (p>0.05).
Conclusion. The results of this study suggest that whole body vibration, associated with strength training, does not produce greater gains in muscle volume and power than strength training alone. We cannot exclude that with a training period longer than the present one (8 weeks) or targeting an elderly population of older age, greater benefits may be seen. A noteworthy and positive observation is that none of the elderly participants found WBV uncomfortable.
Keywords: vibration, training, postmenopausal, muscle volume
References
Rehn B, Lidström J, Skoglund J, Lindström B. Effects on leg muscular performance from whole-body vibration exercise: a systematic review. Scand J Med Sci Sports 2007; 17: 2–11
Skelton DA, Greig CA, Davies JM, Young A. Strength, power and related functional ability of healthy people aged 65–89 years. Age Aging 1994; 23: 371–
Suplemento 39. Diversidad y reconocimiento, aproximaciones al multiculturalismo e interculturalidad en América Latina: Boletín Interno de los investigadores del área de Antropología. 88 (2006) noviembre. Diario de Campo
No full text- Presentación: Multiculturalismo e interculturalidad en América Latina por Alicia M. Barabas. - Notas sobre Multiculturalismo e Interculturalidad por Alicia M. Barabas. - Interculturalidad. Una revisión desde y con los pueblos indígenas (Argentina) por Liliana Tamagno. - Descubriendo la multiculturalidad. El caso chileno por Luis Campos Muñoz. - Indios, negros y ciudadanos. Luchas multiculturales por el reconocimiento (Brasil) por Gabriel O. Álvarez. - Bolivia. Plurinacional e Intercultural por Xavier Albó. - Multiculturalidad e indianismo en el Perú por Juan M. Ossio. - Antropología abierta, antropología ambigua. Tendencias actuales de la antropología ecuatoriana por Segundo E. Moreno Yánez. - Interculturalidad y diversidad cultural en el marco de la revolución bolivariana en Venezuela por Nelly Arvelo Jiménez. - El pluralismo cultural en México por Cristina Oehmichen
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