Quantitative analysis of nonlinear optical input/output of a quantum-dot network based on the echo state property.

The echo state property, which is related to the dynamics of a neural network excited by input driving signals, is one of the well-known fundamental properties of recurrent neural networks. During the echo state, the neural network reveals an internal memory function that enables it to remember past inputs. Due to the echo state property, the neural network will asymptotically update its condition from the initial condition and is expected to exhibit temporally nonlinear input/output. As a physical neural network, we fabricated a quantum-dot network that is driven by sequential optical-pulse inputs and reveals corresponding outputs, by random dispersion of quantum-dots as its components. In the network, the localized optical energy of excited quantum-dots is allowed to transfer to neighboring quantum-dots, and its stagnation time due to multi-step transfers corresponds to the hold time of the echo state of the network. From the experimental results of photon counting of the fluorescence outputs, we observed nonlinear optical input/output of the quantum-dot network due to its echo state property. Its nonlinearity was quantitatively verified by a correlation analysis. As a result, the relation between the nonlinear input/outputs and the individual compositions of the quantum-dot network was clarified.

Intranasal immunization with Leish-111f induces IFN-gamma production and protects mice from Leishmania major infection.

The mucosal vaccination is a non-invasive alternative approach for not only mucosal pathogens but also parenteral pathogens, since it induces both mucosal and systemic immunoreactions. The purpose of this study was to evaluate the application of intranasal (i.n.) immunization with a recombinant leishmanial protein against Leishmania infection. BALB/c mice were i.n. administered 1-3 times with Leish-111f plus cholera toxin (CT) adjuvant (Leish-111f/CT). Splenocytes from i.n. immunized mice produced high level of IFN-gamma but not IL-4 in response to Leish-111f. When infected with 1x10(6) of Leishmania major promastigotes 2 weeks after the final administration, lesion development was completely controlled in all mice i.n. administered with Leish-111f/CT. Mice i.n. administered with Leish-111f alone showed neither cytokine productions nor lesion control even after 6 administrations, suggesting the importance of CT adjuvant. This report demonstrated for the first time that i.n. administration of a recombinant leishmanial protein induces Th1 type immunity and protects mice from Leishmania infection.