Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point.

All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction to a_{µ}^{HVP} for the first time with physical values of m_{u} and m_{d} and dynamical u, d, s, and c quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of δa_{µ}^{HVP,m_{u}≠m_{d}}=+1.5(7)%, in agreement with estimates from phenomenology.

B-meson decay constants from improved lattice nonrelativistic QCD with physical u, d, s, and c quarks.

We present the first lattice QCD calculation of the decay constants f(B) and f(B(s)) with physical light quark masses. We use configurations generated by the MILC Collaboration including the effect of u, d, s, and c highly improved staggered quarks in the sea at three lattice spacings and with three u/d quark mass values going down to the physical value. We use improved nonrelativistic QCD (NRQCD) for the valence b quarks. Our results are f(B)=0.186(4) GeV, f(B(s))=0.224(4) GeV, f(B(s))/f(B)=1.205(7), and M(B(s))-M(B)=85(2) MeV, superseding earlier results with NRQCD b quarks. We discuss the implications of our results for the standard model rates for B((s))→µ(+)µ(-) and B→τν.

Prediction of the bottomonium D-wave spectrum from full lattice QCD.

We calculate the full spectrum of D-wave states in the Υ system in lattice QCD for the first time, by using an improved version of nonrelativistic QCD on coarse and fine "second-generation" gluon field configurations from the MILC Collaboration that include the effect of up, down, strange, and charm quarks in the sea. By taking the 2S-1S splitting to set the lattice spacing, we determine the (3)D2-1S splitting to 2.3% and find agreement with experiment. Our prediction of the fine structure relative to the (3)D2 gives the (3)D3 at 10.181(5) GeV and the (3)D1 at 10.147(6) GeV. We also discuss the overlap of (3)D1 operators with (3)S1 states.

Precise charm to strange mass ratio and light quark masses from full lattice QCD.

By using a single formalism to handle charm, strange, and light valence quarks in full lattice QCD for the first time, we are able to determine ratios of quark masses to 1%. For m(c)/m(s) we obtain 11.85(16), an order of magnitude more precise than the current PDG average. Combined with 1% determinations of the charm quark mass now possible this gives m(s)(2 GeV)=92.4(1.5) MeV. The MILC result for m(s)/m(l)=27.2(3) yields m(l)(2 GeV)=3.40(7) MeV for the average of u and d quark masses.

Prediction of the B{c}{*} mass in full lattice QCD.

By using the highly improved staggered quark formalism to handle charm, strange, and light valence quarks in full lattice QCD, and NRQCD to handle bottom valence quarks, we are able to determine accurately ratios of the B meson vector-pseudoscalar mass splittings, in particular, [m(B{c}{*})-m(B{c})]/[m(B{s}{*})-m(B{s})]. We find this ratio to be 1.15(15), showing the "light" quark mass dependence of this splitting to be very small. Hence we predict m(B{c}{*})=6.330(7)(2)(6) GeV, where the first two errors are from the lattice calculation and the third from existing experiment. This is the most accurate prediction of a gold-plated hadron mass from lattice QCD to date.

Physiological responses to prolonged exercise in ultramarathon athletes.

The physiological responses of 10 ultramarathon athletes to prolonged exercise at the highest intensity level they could sustain for 4 h have been examined. Energy expenditure for the 4 h of exercise was 14,146 +/- 1,789 kJ, of which 63% was provided by the oxidation of fat. Plasma free fatty acids rose, but the changes in blood lactate concentration (delta 0.2 mmol/l) and exchange ratio (delta 0.05) were small, and the postexercise glycogen content (130 +/- 42 mumol/g) of the vastus lateralis muscles was estimated to be 37-53% of normal resting values. During exercise O2 intake (VO2) increased with time from the 50th to 240th min, the rise becoming significant (P less than 0.01) after 110 min of work. The change in VO2 was equivalent to a rise in relative intensity (%VO2max) of +9.1% and a change of speed of 1.49 km/h. A rise in cardiac frequency compensated for a fall in stroke volume (SV), so that cardiac output was maintained, and the increases in rectal temperature (Tre) (delta 0.63 degree C) and sweat loss (3.49 +/- 0.50 kg, equivalent to 5.5% of body wt) and the decreased mean skin temperature (Tsk) (-1.22 degree C) were within tolerable limits during exercise. Following exercise there was a loss (-25%) of ability to generate voluntary force of the quadriceps femoris, though electrically evoked mechanical properties of the muscle remained unchanged. The results suggest that neither thermal nor cardiovascular factors are limiting to prolonged (4 h) exercise, although the ability to utilize fat as a fuel may be important in ultradistance athletes.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrically evoked isokinetic plantar flexor torque in males.

The involuntary angle-specific isokinetic plantar flexor torques of seven male subjects aged 18-21 yr were measured using a Cybex II dynamometer (Lumex) modified by the addition of a strain-gauge load cell to improve the dynamic response of the instrument. Supramaximal electrical stimuli were used to evoke a maximal tetanic response from the triceps surae and ensure constant muscle activation at each angular velocity studied. Angle-specific torques were measured over a range (0.5-5.0 rad/s) of preset velocities, torque decreasing in a nonlinear manner with increasing angular velocity. The torque-velocity data was adequately described by an exponential equation of the form: V = a(e-1/b - e-Po/b) where V = velocity (rad/s), P = torque (N.m), Po = isometric torque (N.m), and a and b are constants. The mean intrasubject coefficient of variation of torque over the range of velocities studies was 7.9 +/- 1.88% (SD).

Effects of load on oxygen intake in trained boys and men during treadmill running.

This investigation examines the effects of vertical and horizontal loading on the O2 intake (VO2) response of children (n = 8) and adults (n = 8) to treadmill running. In unloaded running, the children required a significantly greater VO2 (P less than 0.001) than the adults [mean difference 7 ml.kg-1.min-1 (18.5%)]. There was no significant difference in the VO2 response of the children and the adults to either vertical or horizontal loading. Vertical loading with 5 and 10% of body mass did not produce a significant increase in the VO2 response of either group. In contrast, horizontal loading produced a significant increase (P less than 0.001) in both groups. The consistent response to the two forms of loading suggests that there is no difference between children and adults in the apparent efficiency of running with an external load. Stride frequency showed a significant increase with vertical loading (P less than 0.001) and a significant decrease with horizontal loading (P less than 0.001) in both groups.

Physiological performance and work capacity of Sudanese cane cutters with Schistosoma mansoni infection.

Physiological tests of work performance and measurement of field productivity were made in 194 Sudanese cane cutters in order to study the effect of Schistosoma mansoni infection. The cane cutters were selected from two age ranges (16-24 and 25-45 years) and subdivided into three clinical groups: not infected, infected with, and infected without clinical signs of hepatosplenomegaly. Men infected with Schistosoma haemotobium, malaria (blood film), or with hemoglobin levels less than 10 g/100 ml were excluded. There was a statistically significant (P less than 0.002) higher mean hemoglobin concentration in those not infected but the mean difference was less than 1 g/100 ml. Submaximal responses to exercise on a stationary bicycle ergometer, oxygen intake, ventilation, tidal volume, cardiac frequency and estimated maximal aerobic power output calculated both in absolute terms and relative to lean body mass and leg volume were similar in the six groups of cane cutters. No significant differences were found in physique, body composition or in thermoregulatory function tests. The cane cutters were found to have little natural acclimatization to heat in terms of sweating capacity when compared with a group of fully acclimatized Sudanese soldiers. The mean productivity (mean daily weight of cane cut per man) was significantly correlated with the individual's estimated maximum aerobic capacity determined in the laboratory, but not with the degree of S. mansoni infection. The noninfected group was less "efficient" (mean productivity:oxygen intake) during cutting than the infected groups but a larger proportion of the noninfected were in their first season of cutting. There was a positive correlation between the number of seasons' cutting experience and the individual's age, degree of infection and mean productivity. Cane cutters studied in this investigation were a relatively fit, active population from whom the more seriously ill were excluded. These results do not, therefore necessarily reflect the effects of S. mansoni on physiological work capacity and productivity of more static populations in areas of high endemicity.

The effect of endurance-training on the maximum activities of hexokinase, 6-phosphofructokinase, citrate synthase, and oxoglutarate dehydrogenase in red and white muscles of the rat.

Adult female rats were subjected to an eleven-week endurance-training programme, and, for the first time, the maximum activities of enzymes that can indicate the quantitative capacities of both anaerobic glycolysis and the Krebs cycle in muscle (viz. 6-phosphofructokinase and oxoglutarate dehydrogenase respectively) were measured in heart plus white and fast-oxidative skeletal muscle. No changes were observed in heart muscle. In fast-oxidative skeletal muscle, activities of hexokinase, citrate synthase, and oxoglutarate dehydrogenase were increased by 51, 26, and 33% respectively but there was no effect on 6-phosphofructokinase. These results demonstrate that in red muscle there is no effect of this training programme on the anaerobic capacity but that of the aerobic system is increased by one third. In white skeletal muscle, only the activity of citrate synthase was increased, which indicates that this activity may not provide even qualitative information about changes in capacity of the Krebs cycle.

Isometric training in human elbow flexor muscles. The effects on voluntary and electrically evoked forces.

The elbow flexor muscles of four men were trained using maximal voluntary isometric contractions. Thirty contractions a day were performed for five weeks. The four men and four control subjects were tested once a week: measurements of the supramaximally stimulated isometric twitch force, the time taken for the twitch force to peak and the tetanic force were carried out; simultaneously, measurements of the force of maximal voluntary isometric contraction and resistance to fatigue were made. The testing sessions produced no training effect on control subjects. Training produced a 20 per cent increase in the force of maximal voluntary isometric contraction after five weeks, but the forces of electrically evoked twitch and tetanus showed no increase. It was concluded that the increase in the force of maximal voluntary isometric contraction must be related to factors other than the force-generating capacity of the muscle fibres themselves.