Noninvasive prediction of Blood Lactate through a machine learning-based approach.

We hypothesized that blood lactate concentration([Lac]blood) is a function of cardiopulmonary variables, exercise intensity and some anthropometric elements during aerobic exercise. This investigation aimed to establish a mathematical model to estimate [Lac]blood noninvasively during constant work rate (CWR) exercise of various intensities. 31 healthy participants were recruited and each underwent 4 cardiopulmonary exercise tests: one incremental and three CWR tests (low: 35% of peak work rate for 15 min, moderate: 60% 10 min and high: 90% 4 min). At the end of each CWR test, venous blood was sampled to determine [Lac]blood. 31 trios of CWR tests were employed to construct the mathematical model, which utilized exponential regression combined with Taylor expansion. Good fitting was achieved when the conditions of low and moderate intensity were put in one model; high-intensity in another. Standard deviation of fitting error in the former condition is 0.52; in the latter is 1.82 mmol/liter. Weighting analysis demonstrated that, besides heart rate, respiratory variables are required in the estimation of [Lac]blood in the model of low/moderate intensity. In conclusion, by measuring noninvasive cardio-respiratory parameters, [Lac]blood during CWR exercise can be determined with good accuracy. This should have application in endurance training and future exercise industry

Charmless Three-body Decays of B Mesons

Charmless 3-body decays of B mesons are studied in the framework of the factorization approach. The nonresonant contributions arising from $B\to P_1P_2$ transitions are evaluated using heavy meson chiral perturbation theory (HMChPT). The momentum dependence of nonresonant amplitudes is assumed to be in the exponential form e^{-\alpha_{NR}} p_B\cdot(p_i+p_j)} so that the HMChPT results are recovered in the soft meson limit $p_i, p_j\to 0$. In addition, we have identified another large source of the nonresonant signal in the matrix elements of scalar densities, e.g. $$, which can be constrained from the decay $\bar B^0\to K_SK_SK_S$ or $B^-\to K^-K_SK_S$. The intermediate vector meson contributions to 3-body decays are identified through the vector current, while the scalar meson resonances are mainly associated with the scalar density. Their effects are described in terms of the Breit-Wigner formalism. Our main results are: (i) All KKK modes are dominated by the nonresonant background. The predicted branching ratios of $K^+K^-K_{S(L)}$, $K^+K^-K^-$ and $K^-K_SK_S$ modes are consistent with the data within errors. (ii) Although the penguin-dominated $B^0\to K^+K^-K_{S}$ decay is subject to a potentially significant tree pollution, its effective $\sin 2\beta$ is very similar to that of the $K_SK_SK_S$ mode. However, direct CP asymmetry of the former, being of order -4%, is more prominent than the latter. (iii) For $B\to K\pi\pi$ decays, we found sizable nonresonant contributions in $K^-\pi^+\pi^-$ and $\bar K^0\pi^+\pi^-$ modes, in agreement with the Belle measurements but larger than the BaBar result.Comment: 39 pages, 2 figures, version to appear in PR