14 research outputs found
Unidimensional model of the ad-atom diffusion on a substrate submitted to a standing acoustic wave II. Solutions of the ad-atom motion equation
The ad-atom dynamic equation, a Langevin type equation is analyzed and solved
using some non-linear analytical and numerical tools. We noticeably show that
the effect of the surface acoustic wave is to induce an effective potential
that governs the diffusion of the ad-atom: the minima of this effective
potential correspond to the preferential sites in which the ad-atom spends more
time. The strength of this effective potential is compared to the destructuring
role of the thermal diffusion and to the crystalline potential induced by the
substrate
Unidimensional model of the ad-atom diffusion on a substrate submitted to a standing acoustic wave I. Derivation of the ad-atom motion equation
The effect of a standing acoustic wave on the diffusion of an ad-atom on a
crystalline surface is theoretically studied. We used an unidimensional space
model to study the ad-atom+substrate system. The dynamic equation of the
ad-atom, a Generalized Langevin equation, is analytically derived from the full
Hamiltonian of the ad-atom+substrate system submitted to the acoustic wave. A
detailed analysis of each term of this equation, as well as of their
properties, is presented. Special attention is devoted to the expression of the
effective force induced by the wave on the ad-atom. It has essentially the same
spatial and time dependences as its parent standing acoustic wave
Predictive equations for resting metabolic rate are not appropriate to use in Brazilian male adolescent football athletes.
High accuracy in estimating energy expenditure is essential for enhancing sports performance. The resting metabolic rate (RMR), as a primary component of total energy expenditure (TEE), is commonly estimated using predictive equations. However, these references may not be applicable to adolescent athletes. The purpose of this cross-sectional study was to analyse the differences between predicted RMR in relation to energy expenditure measured by indirect calorimetry (IC) among 45 Brazilian male adolescent football athletes. Indirect calorimetry (IC) and anthropometric (bioimpedance) measurements were recorded at a single visit to the laboratory after fasting overnight. The mean age was 15.6 ± 1.14 years, body mass was 63.05 ± 7.8 kg, and height was 172 ± 7.5 cm. The RMR values predicted by equations proposed by the Food and Agriculture Organization (FAO) (United Nations), Henry and Rees (HR), Harris Benedict (HB), and Cunningham (CUN) were compared with IC RMR values, by correlation analysis. The FAO and HR predictive equations yielded different values from IC (IC: 1716.26 ± 202.58, HR: 1864.87 ± 147.78, FAO: 1854.28 ± 130.19, p = 0.001). A moderate correlation of 0.504 was found between the results of HB and IC. In the survival-agreement model, the CUN equation showed low disagreement with the IC RMR, with error values between 200 and 300 kcal/day. The results showed that HB and CUN yielded similar values as IC, with the CUN equation showing low disagreement with IC; hence, adolescent athletes should undergo evaluation with precise laboratory methods to ensure that accurate information about RMR is recorded