Fingerprint and high-wavenumber Raman spectroscopy in a human-swine coronary xenograft in vivo

Intracoronary Raman spectroscopy could open new avenues for the study and management of coronary artery disease due to its potential to measure the chemical and molecular composition of coronary atherosclerotic lesions. We have fabricated and tested a 1.5-mm-diameter (4.5 Fr) Raman catheter capable of collecting Raman spectra in both the fingerprint (400–1800 cm[superscript −1]) and high-wavenumber (2400–3800 cm[superscript −1]) regions. Spectra were acquired in vivo, using a human-swine xenograft model, in which diseased human coronary arteries are grafted onto a living swine heart, replicating the disease and dynamic environment of the human circulatory system, including pulsatile flow and motion. Results show that distinct spectral differences, corresponding to the morphology and chemical composition of the artery wall, can be identified by intracoronary Raman spectroscopy in vivo.Prescient Medical, Inc.National Institutes of Health (U.S.) (Ruth L. Kirschstein individual fellowship)National Institute of Biomedical Imaging and Bioengineering (U.S.) (Grant no. F31EB007169

Detection of morphological markers of vulnerable atherosclerotic plaque using multimodal spectroscopy

Vulnerable plaques, which are responsible for most acute ischemic events, are presently invisible to x-ray angiography. Their primary morphological features include a thin or ulcerated fibrous cap, a large necrotic core, superficial foam cells, and intraplaque hemorrhage. We present evidence that multimodal spectroscopy (MMS), a novel method that combines diffuse reflectance spectroscopy (DRS), intrinsic fluorescence spectroscopy (IFS), and Raman spectroscopy (RS), can detect these markers of plaque vulnerability. To test this concept, we perform an MMS feasibility study on 17 human carotid artery specimens. Following the acquisition of spectra, each specimen is histologically evaluated. Two parameters from DRS, hemoglobin concentration and a scattering parameter, are used to detect intraplaque hemorrhage and foam cells; an IFS parameter that relates to the amount of collagen in the topmost layers of the tissue is used to detect the presence of a thin fibrous cap; and an RS parameter related to the amount of cholesterol and necrotic material is used to detect necrotic core. Taken together, these spectral parameters can generally identify the vulnerable plaques. The results indicate that MMS provides depth-sensitive and complementary morphological information about plaque composition. A prospective in vivo study will be conducted to validate these findings.National Institutes of Health (U.S.) (Grant R01-HL-64675)National Institutes of Health (U.S.) (Grant P41-RR-02594

Increased efficiencies on CdTe solar cells via luminescence down-shifting with excitation energy transfer between dyes

The external quantum efficiencies of CdTe solar cells fabricated by the atmospheric pressure metal organic chemical vapour deposition (AP–MOCVD) method have been measured with one and two dye doped luminescence down-shifting (LDS) layers on top. Excitation energy transfer between the dyes is used to extend the absorption ability of the LDS layer to ?=350 nm and increase the external quantum efficiency (EQE) of the cells for wavelengths ?<540 nm. The observed increase in the EQE corresponds to a rise in the short circuit current density of 1.88 mA/cm2 under AM1.5G illumination spectra, which is equivalent to a 10% relative solar cell efficiency increase. A simple model is presented, which accounts for the absorption and photon collection efficiencies of the LDS layer

The Impact of Labor Market Entry Conditions on Initial Job Assignment, Human Capital Accumulation, and Wages

We estimate the effects of labor market entry conditions on wages for male individuals first entering the Austrian labor market between 1978 and 2000. We find a large negativ effect of unfavorable entry conditions on starting wages as well as a sizeable negative long-run effect. Specifically, we estimate that a one percentage point increase in the initial local unemployment rate is associated with an approximate shortfall in lifetime earnings of 6.5%. We also show that bad entry conditions are associated with lower quality of a worker's first job and that initial wage shortfalls associated with bad entry conditions only partially evaporate upon involuntary job change. These and additional findings support the view that initial job assignment, in combination with accumulation of occupation or industry-specific human capital while on this first job, plays a key role in generating the observed wage persistencies