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## Characterization of speed fluctuation and drag force in young swimmers: a gender comparison

Barbosa, Tiago M.; Costa, M.J.; Morais, J.E.; Morouço, P.; Moreira, M.; Garrido, N.; Marinho, D.A.; Silva, A.J.
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.54%
The aim of this study was to compare the speed fluctuation and the drag force in young swimmers between genders. Twenty-three young pubertal swimmers (12 boys and 11 girls) volunteered as subjects. Speed fluctuation was measured using a kinematical mechanical method (i.e., speedo-meter) during a maximal 25-m front crawl bout. Active drag, active drag coefficient and power needed to overcome drag were measured with the velocity perturbation method for another two maximal 25 m front crawl bouts with and without the perturbation device. Passive drag and the passive drag coefficient were estimated using the gliding decay velocity method after a maximal push-off from the wall while being fully immersed. The technique drag index was also assessed as a ratio between active and passive drag. Boys presented meaningfully higher speed fluctuation, active drag, power needed to overcome drag and technique drag index than the girls. There were no significant gender differences for active drag coefficient, passive drag and passive drag coefficient. There were positive and moderate- strong associations between active drag and speed fluctuation when controlling the effects of swim velocity. So, increasing speed fluctuation leads to higher drag force values and those are even higher for boys than for girls.

## Growth influences biomechanical profile of talented swimmers during the summer break

Moreira, M.; Morais, J.E.; Marinho, D.A.; Silva, A.J.; Barbosa, Tiago M.; Costa, M.J.
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
16.33%
This study aimed to analyse the effect of growth during a summer break on biomechanical proﬁle of talented swimmers. Twenty-ﬁve young swimmers (12 boys and 13 girls) undertook several anthropometric and biomechanical tests at the end of the 2011–2012 season (pre-test) and 10 weeks later at the beginning of the 2012–2013 season (post-test). Height, arm span, hand surface area, and foot surface area were collected as anthropometric parameters, while stroke frequency, stroke length, stroke index, propelling efﬁciency, active drag, and active drag coefﬁcient were considered as biomechanical variables. The mean swimming velocity during an all-out 25m front crawl effort was used as the performance outcome. After the 10-week break, the swimmers were taller with an increased arm span, hand, and foot areas. Increases in stroke length, stroke index, propelling efﬁciency, and performance were also observed. Conversely, the stroke frequency, active drag, and drag coefﬁcient remained unchanged. When controlling the effect of growth, no signiﬁcant variation was determined on the biomechanical variables. The performance presented high associations with biomechanical and anthropometric parameters at pre-test and post-test, respectively. The results show that young talented swimmers still present biomechanical improvements after a 10-week break...

## Estudo aerodinâmico de uma aeronave utilizando mecânica dos fluidos computacional; Aerodynamic analysis of an aircraft using computational fluid dynamics

Moschetta, Bruno
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
POR
Relevância na Pesquisa
26.38%

## Growth influences biomechanical profile of young talented swimmers after the summer break

Moreira, Marc Francis
ENG
Relevância na Pesquisa
16.33%

## Application of Drag-Reducing Polymer Solutions as Test Fluids for In Vitro Evaluation of Potential Blood Damage in Blood Pumps

Daly, Amanda R.; Sobajima, Hideo; Olia, Salim E.; Takatani, Setsuo; Kameneva, Marina V.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.27%
In vitro evaluation of the potential of a circulatory-assist device to damage blood cells has generally been performed using blood from various species. Problems with this approach include the variability of blood sensitivity to mechanical stress in different species, preparation of blood including the adjustment of hematocrit to a standard value, changes in the mechanical properties of blood that occur during storage, and necessity to pool blood samples to obtain an adequate amount of blood for in vitro circulating systems. We investigated whether the mechanical degradation of a drag-reducing polymer (DRP) solution resulting in the loss of drag-reducing ability can indicate the degree of shear-induced blood damage within blood pumps. DRP solution (polyethylene oxide, 4,500 kDa, 1,000 ppm) or porcine blood were driven through a turbulent flow system by a centrifugal pump, either the Bio-Pump BPX-80 (Medtronic, Inc.) or CentriMag (Levitronix LLC) at a constant pressure gradient of 300 mm Hg for 120 minutes. DRP mechanical degradation was evaluated by reduction of flow rate and solution viscosity. A proposed index of DRP mechanical degradation (PDI) is similar to the normalized index of hemolysis (NIH) typically used to quantify the results of in vitro testing of blood pumps. Results indicate that the mechanical degradation of DRP solutions may provide a sensitive standard method for the evaluation of potential blood trauma produced by blood pumps without the use of blood.

## Effect of long-term dietary lead exposure on some maturation and reproductive parameters of a female Prussian carp (Carassius gibelio B.)

Łuszczek-Trojnar, Ewa; Drąg-Kozak, Ewa; Szczerbik, Paweł; Socha, Magdalena; Popek, Włodzimierz
Fonte: Springer Berlin Heidelberg Publicador: Springer Berlin Heidelberg
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
25.84%
Lead is reported to be an endocrine disruptor. In the current study, we exposed female Prussian carp to artificial feed, supplemented with five doses of dietary Pb (0, 1 (control), 8, 13, 24, and 49 mg/kg) over either a 24-month period or a 12-month period, followed by further 12 months where the fish were fed the control diet. Periodically, oocyte maturation, gonadosomatic index (GSI), ability to secret luteinizing hormone (LH) as well as gonad Pb concentrations were measured. It was found that the reproductive system of the female Prussian carp is not indifferent to chronic exposure to lead. The negative effect was manifested by a decrease in the GSI after 12 months despite the fact that a higher proportion of oocytes at more advanced maturity stages were concurrently observed. After 12 months of exposure, the effect on LH secretion varied according to the dose. In the group exposed to the lowest dose (8 mg/kg), LH decreased spontaneously, and in the groups exposed to the highest two doses (24 and 48 mg/kg), a significantly higher LHRH-A-stimulated LH secretion was observed. After 24 months of lead exposure, the effects on oocyte maturation and size and on GSI values were not pronounced. Analysis of the effect of lead exposure on LH secretion showed that the relationships were similar to those observed after 12 months but nonsignificant. During chronic a 24-month period exposure to Pb...

## Albania - Urban Growth, Migration and Poverty Reduction : A Poverty Assessment

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
25.84%
This sector report claims that in the three years between 2002 and 2005 alone, almost 235,000 people have moved out of poverty in Albania. Strong economic growth and large inflow of remittances are at the center of this impressive achievement. However, low productivity of predominantly small family farms has put a drag on rural growth prospects. Moreover, Ndihma Ekonomike (NE) program, the means-tested income support program is small in scale, and has a low coverage so that it has had only a modest impact on poverty reduction. As a result of these developments, the poor are mostly rural residents, low skilled (measured as years of schooling completed) and large families. The main conclusion of this report is that as Albania looks ahead it faces the challenges of consolidating and sustaining these improvements in living conditions and narrow the widening rural and urban differences. To tackle these challenges, Albania needs to maintain the high growth path, raise rural productivity and improve the targeting performance of its NE program

## Drag coefficient estimation model to simulate dynamic control of autonomous underwater vehicle (AUV) motion

Tan, K.; Lu, T.F.; Anvar, A.
Fonte: The Modelling and Simulation Society of Aust & NZ; Australia Publicador: The Modelling and Simulation Society of Aust & NZ; Australia
Tipo: Conference paper
Relevância na Pesquisa
36.35%
A vehicle dynamics model is crucial for the design of control system for an autonomous underwater vehicle (AUV). However, it is not a simple task to determine the hydrodynamic forces especially the drag coefficient involved for any particular vehicle model. This paper describes a novel approach to approximate the drag coefficient of any given vehicle shapes and sizes using fourth order regression method. The vehicle is subjected to pre-conditioning phase, where it can be done with CFD modelling or subject to simple experimental test within an open environment. In the pre-conditioning phase, the vehicle is required to navigate freely around custom test environment to obtain the drag profile in real-time. With sufficient data, using the correlation 3D graph of drag coefficient and the change in angles, the drag profile of any given shape can be determined. The accuracy of the model is based on the frequency of trial runs, as well as the efficiency of the vehicle’s on-board inertial navigation sensors. In this paper, the proposed approach is being demonstrated using ANSYS-CFX and the results obtained provide close approximation to the real drag coefficient. Therefore, the proposed novel approach is promising and can be used to find the drag coefficients for any given underwater vehicle at any conditions.; http://www.mssanz.org.au/modsim2013/index.html; Kuan M.Tan...

## Sharp nose lens design using refractive index gradient

Amichai, Oded
Tipo: Relatório
EN_US
Relevância na Pesquisa
26.06%
For infrared sensors located at the nose of a missile or a projectile, an age-old problem occurs. A conflict between optical quality and aerodynamic drag exists. A new approach for solving this problem is being developed using gradient refractive index, GRIN, for lens design. The equations for lens design incorporating GRIN are formulated for the special case of spherically symmetrical GRIN. A computer code for designing a GRIN lens and for determining aberrations has been developed. A different program (LENS) calculates lens design and lens performance for the case of homogeneous refractive index. Results of this program provide a check on the more complex program which includes GRIN. The computed program calculates the spot diagram for both meridianal and skew rays. The spot diagram, which is the intersection of rays with the focal plane, is plotted, and the Oj-j^g and centroid location of the spot diagram are calculated. Also a cumulative energy diagram is obtained from the program. The computer code has been organized to calculate the items enumerated above for either a circular cone for the inside or outside surface of the pointed lens. For homogeneous refractive index, both cases are included in the program discussed in this report. However...

## The power output and sprinting performance of young swimmers

Barbosa, Tiago M.; Morais, J.E.; Marques, M.C.; Costa, M.J.; Marinho, D.A.
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.29%
The aim of this article was to compare swimming power output between boys and girls and to model the relationship between swimming power output and sprinting performance in young swimmers. One hundred young swimmers (49 boys and 51 girls, aged between 11 and 13 years) underwent a test battery including anthropometrics (body mass, height, arm span [AS], and trunk transverse surface area), kinematic and efﬁciency (velocity, stroke frequency, stroke length, speed ﬂuc- tuation, normalized speed ﬂuctuation, stroke index, and Froude efﬁciency), hydrodynamics (active drag and active drag coefﬁ- cient), and power output (power to overcome drag, power to transfer kinetic energy to water, and external power) assess- ments and sprinting performance (ofﬁcial 100 freestyle race). All variables but the trunk transverse surface area, stroke length normalize to AS, speed ﬂuctuation, active drag coefﬁcient, and Froude efﬁciency were signiﬁcantly higher in boys than in girls with moderate-strong effects. Comparing both sexes but con- trolling the effect of the sprinting performance, most variables presented a no-signiﬁcant variation. There was a signiﬁcant and strong relationship between power output and sprinting performance: y = 24.179x2.9869 (R2 = 0.426; standard error of estimation = 0.485; p ...

## The use of a computer to obtain flight manual data

Oh, Chang Whan
Tipo: Tese de Doutorado Formato: 87 p.
EN_US
Relevância na Pesquisa
25.84%
Approved for public release; distribution is unlimited; The one thing among many that must be prepared for every flight is the making of a flight plan. Pilots must use charts or graphs from the flight manual to compute the fuel flow that is essential to flight plan. Since this requires many steps of interpolation to compute the specfic conditions that cannot be read directly from flight manual, it is time consuming and increases the probability of making a mistake. This problem obstructs the execution of various mission changes and continuous sorties. A computer program for personal computer or hand-held calculator is developed to compute the desired fuel flow by modifing the equations for an 'IDEAL' airplane; http://archive.org/details/useofcomputertoo00ohch; Major, Republic of Korea Air Force

## Why Don’t Banks Lend to Egypt’s Private Sector?

Herrera, Santiago; Hurlin, Christophe; Zaki, Chahir
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
25.96%
Bank credit to Egypt's private sector decreased over the last decade, despite a recapitalized banking system and high rates of economic growth. Recent macro-economic turmoil has reinforced the trend. This paper explains the decrease based on credit supply and demand considerations by 1) presenting stylized facts regarding the evolution of the banks' sources and fund use in 2005 to 2011, noting two different cycles of external capital flows, and 2) estimating private credit supply and demand equations using quarterly data from 1998 to 2011. The system of simultaneous equations is estimated both assuming continuous market clearing and allowing for transitory price rigidity entailing market disequilibrium. The main results are robust to the market clearing assumption. During the global financial crisis, a significant capital outflow stalled bank deposit growth, which in turn affected the private sector's credit supply. At the same time, the banking sector increased credit to the government. Both factors reduced the private sector's credit supply during the period under study. After the trough of the global crisis...

## World Bank East Asia and Pacific Economic Update, April 2013 : A Fine Balance

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: Publication
EN_US
Relevância na Pesquisa
26.06%
The developing economies of the East Asia and Pacific (EAP) region grew by 7.5 percent in 2012, lower than the 8.3 percent growth recorded in 2011, but still higher than that of any other region. Within the region, available data in the first quarter of the year indicate that external weakness may be abating, while domestic demand remains resilient. The expectation of some stabilization in external demand, coupled with still resilient domestic activity, may be showing in the industrial production and purchasing manager's index numbers, which are generally positive. The growth forecasts for EAP for 2013 and 2014 remain roughly similar to those of December last year. Both the global and regional outlooks are subject to several risks, most of which are by now familiar. Though the developing economies of East Asia are generally well-prepared to absorb external shocks, an emerging concern is the risk of over-heating in some of the larger economies in the region. Policy makers in developing EAP should strive to strike the right balance between managing the near-term risks, and sustaining and increasing inclusive growth in the medium-term by enhancing the underlying productive capacity-human and physical-of these economies.

## World Bank East Asia and Pacific Economic Update 2012, Volume 1 : Capturing New Sources of Growth

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: Publication
EN_US
Relevância na Pesquisa
26.16%
Growth in developing East Asia and the Pacific remained strong in 2011, although it slowed from its post-crisis peaks. Strong domestic demand offset weaker external demand from the United States and Western Europe. Looking ahead, the external environment is likely to remain weak. The best prospects for the region to maintain high rates of growth, job creation, and poverty reduction are through rebalancing towards domestic demand and investing in productivity increases and further international integration. The region remains vulnerable to the continued uncertainty in Europe through trade and financial linkages. Although last December's fiscal pact and liquidity support from the European Central Bank helped stabilize financial markets, recent political events and market developments point to continued challenges. Renewed market volatility and a further slowdown in European economies cannot be ruled out. The European Union (EU), along with the US and Japan, accounts for over 40 percent of the region's direct export shipments and an estimated 60 percent if intraregional trade linked to production networks is taken into account. A serious disruption in the EU would also have knock-on effects on East Asia's exports and growth by lowering growth in other regions...

## Quasi-stationary States of Dust Flows Under Poynting-Robertson Drag: New Analytical and Numerical Solutions

Gor'kavyi, N. N.; Ozernoy, L. M.; Mather, J. C.; Taidakova, T.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.15%
The effect of solar or stellar radiation on dust particles' trajectories (the Poynting-Robertson drag) has been studied by a number of authors and applied to interplanetary dust dynamics in numerical computations. Meanwhile some important features of dust flows can be studied analytically by implementing our novel hydrodynamical approach to use the continuity equation written in the particle's orbital elements as coordinates (Gor'kavyi, Ozernoy, & Mather 1997). By employing this approach and integrating the continuity equation, we are able to find two integrals of motion when the Poynting-Robertson drag dominates the dissipative forces in the dust flow. These integrals of motion enable us to explore basic characteristics of dust flows from any sources in the Solar system (such as asteroids, comets, Kuiper belt, etc.) or in another planetary system. In particular, we have reproduced the classical solution $n(r)\propto r^{-1}$ that approximately represents the overall distribution of dust in the Solar system. We have also investigated various factors that could be responsible for the deviations of the power law index in $n(r)\propto r^{\delta}$ from $\delta=-1$, including the influences of the orbital characteristics of dust sources...

## Experimental Constraints of Using Slow-Light in Sodium Vapor for Light-Drag Enhanced Relative Rotation Sensing

Tripathi, Renu; Pati, G. S.; Messall, M.; Salit, K.; Shahriar, M. S.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.84%
We report on experimental observation of electromagnetically induced transparency and slow-light (vg ~ c/607) in atomic sodium vapor, as a potential medium for a recently proposed experiment on slow-light enhanced relative rotation sensing [11]. We have performed an interferometric measurement of the index variation associated with a two-photon resonance to estimate the dispersion characteristics of the medium that is relevant to the slow-light based rotation sensing scheme. We also show that the presence of counter-propagating pump beams in an optical Sagnac loop produces a backward optical phase conjugation beam that can generate spurious signals, which may complicate the measurement of small rotations in the slow-light enhanced gyroscope. We identify techniques for overcoming this constraint.; Comment: 18 pages, 8 figures

## Nonlinear Dynamical Friction of a Circular-Orbit Perturber in a Gaseous Medium

Kim, Woong-Tae
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
16.26%
We use three-dimensional hydrodynamic simulations to investigate the nonlinear gravitational responses of gas to, and the resulting drag forces on, very massive perturbers moving on circular orbits. This work extends our previous studies that explored the cases of low-mass perturbers on circular orbits and massive perturbers on straight-line trajectories. The background medium is assumed to be non-rotating, adiabatic with index 5/3, and uniform with density rho0 and sound speed a0. We model the gravitating perturber using a Plummer sphere with mass Mp and softening radius rs in a uniform circular motion at speed Vp and orbital radius Rp, and run various models with differing R=rs/Rp, Mach=Vp/a0, and B=G*Mp/(a0^2*Rp). A quasi-steady density wake of a supersonic model consists of a hydrostatic envelope surrounding the perturber, an upstream bow shock, and a trailing low-density region. The continuous change in the direction of the perturber motion makes the detached shock distance reduced compared to the linear-trajectory cases, while the orbit-averaged gravity of the perturber gathers the gas toward the center of the orbit, modifying the background preshock density to rho1=(1 + 0.46B)*rho0 depending weakly on Mach. For sufficiently massive perturbers...

## Inertial forces - a la Newton in General Relativity

Prasanna, A. R.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.84%
In this we briefly cover the covariant approach to describe inertial forces in general relativity and in particular look at the behaviour of the cumulative drag index for stationary Kerr geometry.; Comment: Lecture notes 18 pages including five figs

## Cumulative Dragging - An Intrinsic Characteristic of Stationary Axisymmetric Spacetime

Prasanna, A. R.; Iyer, Sai
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.28%
The Cumulative Drag Index defined recently by Prasanna has been generalised to include the centrifugal acceleration. We have studied the behaviour of the drag index for the Kerr metric and the Neugebauer-Meinel metric representing a self-gravitating rotating disk and their Newtonian approximations. The similarity of the behaviour of the index for a given set of parameters both in the full and approximated forms, suggests that the index characterises an intrinsic property of spacetime with rotation. Analysing the index for a given set of parameters shows possible constraints on them.; Comment: Discussion of Neugebauer-Meinel rotating disk and clarifications added

## Análise descritiva do desempenho em uma prova de 100 m nado livre feminino baseada em variáveis biomecânicas; Descriptive analysis of performance in the female 100 meters free swimming based on biomechanics variables

Farah, Breno Quintella; Silva, Windson Carlos Motta; Santos, Marcos André; Melo, Wilson Viana de Castro
Fonte: Universidade de São Paulo. Escola de Educação Física e Esporte Publicador: Universidade de São Paulo. Escola de Educação Física e Esporte
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf