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Biomedical subjects

M J Lea

Publications and source records attributed to M J Lea.

4 recordsLinked to original sources
PubMed2002

Microwave saturation of the Rydberg States of electrons on helium.

We present measurements of the resonant microwave excitation of Rydberg energy levels for surface-state electrons on superfluid helium. The temperature-dependent contribution to the linewidth gamma(T) agrees with theoretical predictions and is very small below 700 mK, in the ripplon scattering regime. Absorption saturation and power broadening were observed as the fraction of electrons in the first excited state was increased to 0.49, close to the thermal excitation limit of 0.5. The Rabi frequency Omega was determined as a function of microwave power. High values of the ratio Omega/gamma confirm this system as an excellent candidate for creating qubits.

Journal Article↗
PubMed2001

Observation of dynamical ordering in a confined Wigner crystal.

We present measurements of the conduction of nondegenerate free electrons along a low-dimensional channel at low temperatures, using surface-state electrons on liquid helium in novel microelectronic devices. Above 1 K, the electrons form an ideal classical Drude conductor. Below 1 K, Coulomb interactions produce electronic spatial order, leading to strong non-Ohmic effects and negative differential conductivity. Evidence is presented for self-organized current filaments in the channel, created by a nonequilibrium phase transition. Periodic conductance oscillations suggest an anisotropic spatial order with lines of electrons along the channel edges.

Journal Article↗
PubMed1985

Descriptive epidemiology of night sweats upon admission to a university hospital.

Between March 1 and Sept 1, 1980, we interviewed a 25% random sample of patients admitted to medicine, surgery, and obstetric, and gynecology services to determine the frequency and descriptive characteristics of night sweats (NS). Seventy-two (41%) of 174 patients interviewed reported NS within three months before admission. Obstetric patients reported NS significantly more often than nonobstetric patients (60% vs 33%, P less than .02). The duration of NS ranged from one day to 27 years (mean 10.5 months; median two months). NS were mild in 36 (50%), moderate in 17 (24%), and severe in 19 (26%). Severe NS were reported significantly more often by nonobstetric patients, and most often by those on the medicine service. Among nonobstetric patients, NS were associated with metastatic adenocarcinoma of the prostate gland, and severe NS with the use of antipyretics. NS were not associated with elevated temperature measurements during hospitalization.

Adolescent↗