I was asked to give a brief review of the black hole-STRING correspondence [1] as a warm-up for a longer SITP-group discussion of a recent paper by Chen, Maldacena, and Witten [2]. Here are my notes in written form.

Objective: determining difference limen for Frequency (DLF) in STRING musicians. Materials &Methods: This case-control study was conducted on 15STRING musicians with musicianship> 10 years (30 ears) and 15 normal hearing subjects (30 ears). They all were male and 20-30 years old. DLF was measured after otoscopy and immitance audiometry and pure tone audiometry. Results: DLF was significantly different between two groups of case and control. DLF in musicians is less than the normal hearing subjects. Conclusion: It seems that familiarization with notes results in better DLF in musicians comparing to others.

The governing equations of motion for a drill STRING considering coupling between axial, lateral and torsional vibrations are obtained using a Lagrangian approach. The result leads to a set of non-linear equations with time varying coefficients. A fully coupled model for axial, lateral, and torsional vibrations of drill STRINGs is presented. The bit/formation interactions are assumed to be related to the following parameters: bit motion, effects of gyroscopic moments, contact with the borehole wall, axial excitation due to bit/formation interactions, and hydrodynamic damping due to the presence of drilling mud. Simulation results show that parametric resonance and whirling may occur simultaneously within the range of operating conditions of drilling. The contact force between collar and borehole wall is calculated and its behavior is investigated. The dynamic behavior is quite complicated and may become non-periodic, suggesting a chaotic behavior.

Doppler ultrasound system is of great importance among the diagnostic modalities. To ensure the output of such systems that measure the physiological quantities, performance tests were carried out using AIUM and BSI protocols on 20 pulsed wave Doppler systems in 9 reference centers in Tehran. In these tests, velocity of Doppler ultrasound systems as an acoustic parameter was assessed. To evaluate the performance of pulsed wave Doppler, an in-house STRING phantom was designed for the first time in the country. This phantom was used to investigate pulsed Doppler ultrasound systems. The results show that the minimum and maximum errors in blood flow velocity measurement on 20 Doppler systems were 23 (cm/s) and 83 (cm/s), respectively. The mean± SD for velocity measurement errors in 6 Doppler systems (7. 5 MHz) and 12 systems (3. 5 MHz) were 11± 16 and 28± 9 (cm/s), respectively, the velocities ranged 10-140 (cm/s). These errors emphasize the necessity for doing performance tests in Doppler ultrasonic systems.

The holography principle relates the quantum gravity in the bulk, described by closed STRING, the gauge theory, described by open STRING on the boundary with certain asymptotic conditions. Thus, it is important to understand intimate relations between open STRING theory and closed STRING theory: In the present work we propose a cubic closed STRING field theory, introducing a double layer to describe the closed STRING world-sheet as an extension of the open STRING world-sheet of the Witten's cubic open STRING. We mapped the closed STRING world-sheet onto the complex plane, of which the lower half plane is completely covered by the extended part of the STRING world-sheet. Using the Green's function on the complex plane, evaluated the Polyakov STRING path integral, from which we extracted the Neumann functions and the vertex operators.