Optically induced coherent intra-band dynamics in disordered semiconductors

On the basis of a tight-binding model for a strongly disordered semiconductor with correlated conduction- and valence band disorder a new coherent dynamical intra-band effect is analyzed. For systems that are excited by two, specially designed ultrashort light-pulse sequences delayed by tau relatively to each other echo-like phenomena are predicted to occur. In addition to the inter-band photon echo which shows up at exactly t=2*tau relative to the first pulse, the system responds with two spontaneous intra-band current pulses preceding and following the appearance of the photon echo. The temporal splitting depends on the electron-hole mass ratio. Calculating the population relaxation rate due to Coulomb scattering, it is concluded that the predicted new dynamical effect should be experimentally observable in an interacting and strongly disordered system, such as the Quantum-Coulomb-Glass.Comment: to be published in Physical Review B15 February 200

Cross-reactions of sera from dogs infected with <it>Angiostrongylus vasorum</it> in commercially available <it>Dirofilaria immitis</it> test kits

<p>Abstract</p> <p>Background</p> <p><it>Dirofilaria immitis</it> and <it>Angiostrongylus vasorum</it> are both important potentially fatal canine nematodes with overlapping endemic areas, especially in Europe. The preadult and adult stages of both species are living in the Arteria pulmonalis and the right heart, and diagnostically detectable circulating parasite antigens have been demonstrated for both species. For the detection of <it>D. immitis</it> infections, a variety of commercial tests have been developed, however, they have not been evaluated for cross-reactions against circulating antigens of <it>A. vasorum.</it></p> <p>Methods</p> <p>In this study, potential cross-reactions of sera from 16 dogs, which were experimentally infected with <it>A. vasorum</it> and which had circulating antigens as confirmed by a species-specific ELISA, were evaluated for the detection of <it>A. vasorum</it> antigen in six commercially available <it>D. immitis</it> test kits.</p> <p>Results</p> <p>In three fast tests (Witness® Dirofilaria, SensPERT® Canine Heartworm, SNAP® 4Dx® Plus), all sera were negative. One fast membrane ELISA (SNAP® HTWM RT Test) was positive with four sera (25%), and one serum delivered a non-valid result twice. In the PetChek® HTWM PF Test, depending on the interpretation protocol, 5 or 8 dogs (31.2 – 50%) were positive. With the DiroCHEK®-ELISA, a single <it>A. vasorum</it>-infected dog (6.2%) tested positive.</p> <p>Conclusions</p> <p>Due to potential cross-reactions with <it>A. vasorum</it> in commercially available test kits for the detection of <it>D. immitis</it> antigen, the simultaneous use of highly specific diagnostic methods for the differentiation of these two canine heart worms is recommended.</p