Blood lactate clearance after maximal exercise depends on active recovery intensity

AIM: High-intensity exercise is time-limited by onset of fatigue, marked by accumulation of blood lactate. This is accentuated at maximal, all-out exercise that rapidly accumulates high blood lactate. The optimal active recovery intensity for clearing lactate after such maximal, all-out exercise remains unknown. Thus, we studied the intensity-dependence of lactate clearance during active recovery after maximal exercise.<p></p> METHODS: We constructed a standardized maximal, all-out treadmill exercise protocol that predictably lead to voluntary exhaustion and blood lactate concentration >10 mM. Next, subjects ran series of all-out bouts that increased blood lactate concentration to 11.5±0.2 mM, followed by recovery exercises ranging 0% (passive)-100% of the lactate threshold.<p></p> RESULTS: Repeated measurements showed faster lactate clearance during active versus passive recovery (P<0.01), and that active recovery at 60-100% of lactate threshold was more efficient for lactate clearance than lower intensity recovery (P<0.05). Active recovery at 80% of lactate threshold had the highest rate of and shortest time constant for lactate clearance (P<0.05), whereas the response during the other intensities was graded (100%=60%>40%>passive recovery, P<0.05).<p></p> CONCLUSION: Active recovery after maximal all-out exercise clears accumulated blood lactate faster than passive recovery in an intensity-dependent manner, with maximum clearance occurring at active recovery of 80% of lactate threshold

Pedagogy, Protests, and Moving Toward Progress

Our world is in constant flux and educators are at the ship’s helm steering toward what former U.S. Representative John Lewis called “good trouble.” However, in many cases, educators lack the training required to be most effective in doing so. As instructors face student demands to address topics on race and social justice, many educators are unsure about how to respond appropriately to the chants of “No Justice, No Peace!” Thus, this essay explores humanistic and pragmatic approaches for doing so in terms of fostering cultural communication competence when incorporating topics on race and social justice issues in the classroom

Granular circulation in a cylindrical pan: simulations of reversing radial and tangential flows

Granular flows due to simultaneous vertical and horizontal excitations of a flat-bottomed cylindrical pan are investigated using event-driven molecular dynamics simulations. In agreement with recent experimental results, we observe a transition from a solid-like state, to a fluidized state in which circulatory flow occurs simultaneously in the radial and tangential directions. By going beyond the range of conditions explored experimentally, we find that each of these circulations reverse their direction as a function of the control parameters of the motion. We numerically evaluate the dynamical phase diagram for this system and show, using a simple model, that the solid-fluid transition can be understood in terms of a critical value of the radial acceleration of the pan bottom; and that the circulation reversals are controlled by the phase shift relating the horizontal and vertical components of the vibrations. We also discuss the crucial role played by the geometry of the boundary conditions, and point out a relationship of the circulation observed here and the flows generated in vibratory conveyors.Comment: 10 pages, 8 figure

Interplay Between Time-Temperature-Transformation and the Liquid-Liquid Phase Transition in Water

We study the TIP5P water model proposed by Mahoney and Jorgensen, which is closer to real water than previously-proposed classical pairwise additive potentials. We simulate the model in a wide range of deeply supercooled states and find (i) the existence of a non-monotonic ``nose-shaped'' temperature of maximum density line and a non-reentrant spinodal, (ii) the presence of a low temperature phase transition, (iii) the free evolution of bulk water to ice, and (iv) the time-temperature-transformation curves at different densities.Comment: RevTeX4, 4 pages, 4 eps figure

Carrier thermal escape in families of InAs/InP self-assembled quantum dots

We investigate the thermal quenching of the multimodal photoluminescence from InAs/InP (001) self-assembled quantum dots. The temperature evolution of the photoluminescence spectra of two samples is followed from 10 K to 300 K. We develop a coupled rate-equation model that includes the effect of carrier thermal escape from a quantum dot to the wetting layer and to the InP matrix, followed by transport, recapture or non-radiative recombination. Our model reproduces the temperature dependence of the emission of each family of quantum dots with a single set of parameters. We find that the main escape mechanism of the carriers confined in the quantum dots is through thermal emission to the wetting layer. The activation energy for this process is found to be close to one-half the energy difference between that of a given family of quantum dots and that of the wetting layer as measured by photoluminescence excitation experiments. This indicates that electron and holes exit the InAs quantum dots as correlated pairs

A SQUAMOSA MADS-box gene involved in the regulation of anthocyanin accumulation in bilberry fruits

Anthocyanins are important health promoting phytochemicals that are abundant in many fleshy fruits. Bilberry (Vaccinium myrtillus L.) is one of the best sources of these compounds. Here we report on the expression pattern and functional analysis of a SQUAMOSA (SQUA) class MADS-box transcription factor, VmTDR4, associated with anthocyanin biosynthesis in bilberry. Levels of VmTDR4 expression were spatially and temporally linked with colour development and anthocyanin-related gene expression. Virus induced gene silencing (VIGS) was used to suppress VmTDR4 expression in bilberry resulting in substantial reduction in anthocyanin levels in fully ripe fruits. Chalcone synthase was used a positive control in the VIGS experiments. Additionally, in sectors of fruit tissue in which the expression of the VmTDR4 gene was silenced, the expression of R2R3 MYB family transcription factors related to the biosynthesis of flavonoids were also altered. We conclude that VmTDR4 plays an important role in the accumulation of anthocyanins during normal ripening in bilberry; probably through direct or indirect control of transcription factors belonging to the R2R3 MYB family

Carbon isotope effect in superconducting MgCNi_3

The effect of Carbon isotope substitution on T_c in the intermetallic perovskite superconductor MgCNi_3 is reported. Four independent groups of samples were synthesized and characterized. The average T_c for the Carbon-12 samples was found to be 7.12(2) K and the average T_c for the Carbon-13 samples was found to be 6.82(2) K. The resulting carbon isotope effect coefficient is alfa_C = 0.54(3). This indicates that carbon-based phonons play a critical role in the presence of superconductivity in this compound.Comment: To be published in Phys. Rev. B. 4 pages, 1 figur

Scanning Quantum Decoherence Microscopy

The use of qubits as sensitive magnetometers has been studied theoretically and recent demonstrated experimentally. In this paper we propose a generalisation of this concept, where a scanning two-state quantum system is used to probe the subtle effects of decoherence (as well as its surrounding electromagnetic environment). Mapping both the Hamiltonian and decoherence properties of a qubit simultaneously, provides a unique image of the magnetic (or electric) field properties at the nanoscale. The resulting images are sensitive to the temporal as well as spatial variation in the fields created by the sample. As an example we theoretically study two applications of this technology; one from condensed matter physics, the other biophysics. The individual components required to realise the simplest version of this device (characterisation and measurement of qubits, nanoscale positioning) have already been demonstrated experimentally.Comment: 11 pages, 5 low quality (but arXiv friendly) image