Spectral method for characterization of avalanche photodiode working as single-photon detector

In this Letter, a new method for avalanche photodiode characterization, based on the spectral analysis of the photocurrent produced during an avalanche, is proposed. The theory is developed, and an experimental characterization of an avalanche photodiode working in the Geiger mode with CW laser is performed.     

Ultrastructure and morphometry of the egg of Psorophora albigenu Lutz, 1908 (Diptera: Culicidae)

Eggs of Psorophora albigenu were analyzed by light and scanning electron microscopy. Eggs were laid singly and were black and elliptical in outline. A length of approximately 586.4 ± 10.83 μm, a width of 172.3 ± 8.09 μm (n=30), and an egg index (length/width ratio) of 3.33 were observed. The anterior extremity tapered abruptly from a width of 64.9 μm, while such tapering was more gradual at the posterior extremity from a width of 77.4 μm. The ventral surface of the chorionic coating presented cells with tubular aspect containing tubercles in rows with a density of 9-16 tubercles per cell. These tubercles presented two different sizes, with the largest measuring 7.87 ± 01.58 μm and the smallest measuring 0.71 ± 0.53 μm (n=30) in longitudinal diameter. The micropyle orifice was very evident, with a diameter of 3.36 μm. The morphometric characteristics of Ps. albigenu obtained in this study were distinct from those of other species of the Psorophora genus, including Psorophora varipes which has been considered for a long time to be synonymous with Ps. albigenu.