Observation of long spin-relaxation times in bilayer graphene at room temperature.

We report on the first systematic study of spin transport in bilayer graphene (BLG) as a function of mobility, minimum conductivity, charge density, and temperature. The spin-relaxation time τ(s) scales inversely with the mobility µ of BLG samples both at room temperature (RT) and at low temperature (LT). This indicates the importance of D'yakonov-Perel' spin scattering in BLG. Spin-relaxation times of up to 2 ns at RT are observed in samples with the lowest mobility. These times are an order of magnitude longer than any values previously reported for single-layer graphene (SLG). We discuss the role of intrinsic and extrinsic factors that could lead to the dominance of D'yakonov-Perel' spin scattering in BLG. In comparison to SLG, significant changes in the carrier density dependence of τ(s) are observed as a function of temperature.

Electrocardiographic changes during exercise in asymptomatic men: 3-year follow-up.

Electrocardiographic (ECG) changes during maximal bicycle exercise and risk factors for coronary heart disease (CHD) were studied in 510 male civic employees who were followed for 3 years. Clinical CHD developed in 15 (24.6 percent) of the 61 men with an ischemic exercise ECG on the initial examination and in 11 (2.4 percent) of the 449 subjects with a normal initial exercise ECG. A normal maximal exercise ECG is no guarantee that severe CHD does not exist and that a subject will not soon sustain major myocardial damage; and an ischemic exercise ECG does not necessarily indicate underlying CHD. In the former group angina was the most frequent clinical CHD episode; in the latter group, infarction. Among those with an abnormal initial exercise ECG, CHD was most likely to develop in association with a poor exercise capacity. Subjects with subsequent clinical CHD and those with abnormal ECGs after 3 years tended to have a higher frequency of risk factors; subjects whose abnormal ECGs reverted to normal after 3 years tended to have a lower frequency of risk factors.

Exercise ECG changes in normal women.

Submaximal and/or maximal exercise was carried out by 357 women without a history of cardiovascular disease, using a bicycle ergometer and/or treadmill while monitored by a bipolar ECG lead CM(5). In 40- to 60-year-old women the incidence of an ischemic ECG pattern during or after exercise ranged from 20 to 50%. Because clinical coronary disease can be expected in less than 10% of normal women followed for 16 years, most of these ECG changes were not considered to be due to occult coronary disease. At the present time exercise ECG changes in women cannot be used with any reliability as an aid in the diagnosis of chest pain or in screening normal female populations for coronary heart disease.