Transcend Vivoscope (China)

Development of miniature two-photon microscopy (m2PM) has made it possible to observe fine structure and activity of neurons in the brain of freely moving animals. However, the imaging field-of-view of existing m2PM is still significantly smaller than that of miniature single-photon microscopy. Here we report that, through the design of low-magnification objective, large field-of-view scan lens and small tilt angle microscanner, a 2.5-g m2PM achieved a field-of-view of 1000 × 788 µm2, comparable to that of a typical single-photon miniscope. We demonstrated its capability by imaging neurons, dendrites and spines in the millimeter field-of-view, and simultaneous recording calcium activities, through a gradient-index lens, of approximately 400 neurons in the dorsal hippocampal CA1 in a freely moving mouse. Integrated with a detachable 1.2-g fast z-scanning module, it enables a 1000 × 788 × 500 µm3 volumetric neuronal imaging in the cerebral cortex. Thus, millimeter FOV m2PM provides a powerful tool for deciphering neuronal population dynamics in experimental paradigms allowing for animal's free movement.

Miniature two-photon microscopy combines the two-photon excitation principle and is more lightweight and flexible, allowing it to be applied to freely behaving animals. The piezoelectric tube (PZT) fiber scanner is the key actuated component in miniature fiber-scanning two-photon endomicroscopy (TPEM). In this paper, we use multi-physics field finite element simulation to model and analyze a reverse-fixed PZT fiber scanner for TPEM. The simulation results show that the first two resonant frequencies of the PZT fiber scanner are 163.6 Hz and 757.9 Hz, respectively. At the first two resonant points, the PZT fiber scanner scan range are 0.078 mm and 0.68 mm, respectively. Theoretical guidance for frequency selection of the reverse-fixed PZT fiber scanner is provided by these simulation results.

We demonstrate a mode-locked NALM polarization-maintaining Nd:fiber laser at 920 nm with a repetition rate of 43.6 MHz. The average output power is 8 mW and the pulse width is 109 fs.

In this paper we discuss a new approach to Perfor mance Engineering called the Object-Oriented Per formance Engineering Approach (OOPEA). OOPEA is an innovative approach to performance modeling, simulation and design where an object-oriented per formance analysis model, a discrete-event simula tion model and an operational model are integrated into a modeling framework. We emphasize simula tion in this paper and present a case study on the UICCELL II (University of Illinois at Chicago CELLular II switching system), a software simula tor of a cellular phone system. The system can be divided into three main components: the Mobile Switching Center, Base Site, and Mobile Telephone Unit, which have client-server relationships and communicate with each other using IPC facilities, via message passing. The UICCELL II is implemented in a distributed environment on SUN SPARC 1 and 10 workstations using an Ethernet LAN. Sim ulation is used to examine the dynamic behavior of the system, and helps to capture the performance constraints, mainly the contention for resources.