Single-shot characterization of vector beams by generalized measurements.

Vector vortex beams, featuring independent spatial modes in orthogonal polarization components, offer an increase in information density for emerging applications in both classical and quantum communication technology. Recent advances in optical instrumentation have led to the ability of generating and manipulating such beams. Their tomography is generally accomplished by projection measurements to identify polarization as well as spatial modes. In this paper we demonstrate spatially resolved generalized measurements of arbitrary vector vortex beams. We perform positive operator valued measurements (POVMs) in an interferometric setup that characterizes the vector light mode in a single-shot. This offers superior data acquisition speed compared to conventional Stokes tomography techniques, with potential benefits for communication protocols as well as dynamic polarization microscopy of materials.

Inverted electron-hole alignment in InAs-GaAs self-assembled quantum dots.

New information on the electron-hole wave functions in InAs-GaAs self-assembled quantum dots is deduced from Stark effect spectroscopy. Most unexpectedly it is shown that the hole is localized towards the top of the dot, above the electron, an alignment that is inverted relative to the predictions of all recent calculations. We are able to obtain new information on the structure and composition of buried quantum dots from modeling of the data. We also demonstrate that the excited state transitions arise from lateral quantization and that tuning through the inhomogeneous distribution of dot energies can be achieved by variation of electric field.

Timing of stress testing in an asymptomatic survivor of inferior myocardial infarction.

Exercise electrocardiography with or without thallium-201 scintigraphy was performed (pre-hospital discharge) in 66 asymptomatic survivors of a first inferior myocardial infarction (IMI). Although coronary angiography revealed an 82% incidence of multivessel coronary artery disease (MV-CAD) in the total cohort, the sensitivity of exercise ECG for MV-CAD in the group with absent anterior ST-depression in the acute phase was low (11%). In contrast the presence of acute phase anterior ST-segment depression improved the yield for MV-CAD to 55%. Forty-six patients agreed to a symptom-limited exercise ECG plus/minus thallium imaging at 8-10 weeks post IMI. The sensitivity of detecting MV-CAD improved by 15% in patients with no acute phase anterior ST-segment depression and 16% in patients with acute phase anterior ST-segment depression. At each exercise protocol, thallium improved the sensitivity of exercise in detecting ischemia in the noninfarct zone. It is concluded that following IMI, a high percentage of asymptomatic patients whose acute phase ECG showed anterior ST-segment depression will have MV-CAD detected by heart-rate limited and, more so, by symptom-limited exercise ECG. The detection rate will double in patients with no anterior ST-segment depression if exercise testing is delayed until 8-10 weeks post IMI.

Nifedipine induced bradycardia in a patient with autonomic neuropathy.

An 80 year old diabetic male with evidence of peripheral and autonomic neuropathy was admitted with chest pain. He was found to have atrial flutter at a ventricular rate of 70/min which slowed down to 30-40/min when nifedipine (60 mg) in 3 divided doses, during which he was paced at a rate of 70/min. This is inconsistent with the well-established finding that nifedipine induces tachycardia in normally innervated hearts. However, in hearts deprived of compensatory sympathetic drive, it may lead to bradycardia.

Lipoproteins and apolipoproteins in young male survivors of myocardial infarction.

Plasma and lipoprotein cholesterol, triglycerides, apolipoproteins (apo) A-I, A-II, B and phospholipid concentrations were measured at 10 days and 4 months after myocardial infarction (MI) in 60 young Kuwaiti male MI survivors below the age of 40 years. Controls were matched for age, relative weights, smoking, dietary habits and physical activities. The young MI survivors had significantly higher levels of total and LDL-cholesterol, and ratios of LDL/HDL- and LDL/HDL2-cholesterol. Total VLDL and LDL triglycerides, and phospholipids were also elevated in MI survivors compared to controls. Similarly, plasma and LDL-apo B as well as the ratios of apo B/apo A-I were higher in the MI group. There was no significant change in the levels of VLDL and HDL3-cholesterol and of apo A-II in these patients compared to their controls. Concentrations of HDL- and HDL2-cholesterol and of plasma and HDL apo A-I were significantly lower in the young MI survivors compared to the control subjects. The better discriminating lipoproteins and apolipoproteins in MI patients in descending order were HDL2-cholesterol greater than apo B greater than apo A-I greater than VLDL-triglyceride greater than HDL-cholesterol greater than LDL/HDL2-cholesterol greater than triglycerides. The data indicate that measurement of HDL2-cholesterol, apo B and apo A-I may be useful indicators in assessing coronary artery disease risk than triglycerides (TG), total cholesterol (TC), LDL-cholesterol and HDL-cholesterol.