Auto-tracking camera for dry-box laparoscopic training

While laparoscopic surgery is less invasive than open surgery and is now common in various medical fields, laparoscopic surgery often requires more time for the operator to achieve mastery. Dry box training is one of the most important methods for developing laparoscopic skill. However, the camera is usually fixed to a particular point, which is different from practical surgery, during which the operational field is constantly adjusted by an assistant. Therefore, we introduced a camera for dry box training that can be moved by surgeons as desired by using computer vision. By detecting the ArUco marker, the camera attached onto the servomotor successfully tracked the forceps automatically. This system could easily be modified and become operable by a foot switch or voice, and collaborations between surgeons and medical engineers are expected

A New Constraint on the Lyα\alpha Fraction of UV Very Bright Galaxies at Redshift 7

We study the extent to which very bright (-23.0 < MUV < -21.75) Lyman-break selected galaxies at redshifts z~7 display detectable Lya emission. To explore this issue, we have obtained follow-up optical spectroscopy of 9 z~7 galaxies from a parent sample of 24 z~7 galaxy candidates selected from the 1.65 sq.deg COSMOS-UltraVISTA and SXDS-UDS survey fields using the latest near-infrared public survey data, and new ultra-deep Subaru z'-band imaging (which we also present and describe in this paper). Our spectroscopy has yielded only one possible detection of Lya at z=7.168 with a rest-frame equivalent width EW_0 = 3.7 (+1.7/-1.1) Angstrom. The relative weakness of this line, combined with our failure to detect Lya emission from the other spectroscopic targets allows us to place a new upper limit on the prevalence of strong Lya emission at these redshifts. For conservative calculation and to facilitate comparison with previous studies at lower redshifts, we derive a 1-sigma upper limit on the fraction of UV bright galaxies at z~7 that display EW_0 > 50 Angstrom, which we estimate to be < 0.23. This result may indicate a weak trend where the fraction of strong Lya emitters ceases to rise, and possibly falls between z~6 and z~7. Our results also leave open the possibility that strong Lya may still be more prevalent in the brightest galaxies in the reionization era than their fainter counterparts. A larger spectroscopic sample of galaxies is required to derive a more reliable constraint on the neutral hydrogen fraction at z~7 based on the Lya fraction in the bright galaxies.Comment: 20 pages, 7 figures, accepted for publication in Ap

CS-08-02 Strange Behaviors of Interior-point Methods for Solving Semidefinite Programming Problems in Polynomial Optimization

We observe that in a simple one-dimensional polynomial optimization problem (POP), the ‘optimal ’ values of semidefinite programming (SDP) relaxation problems reported by the standard SDP solvers converge to the optimal value of the POP, while the true optimal values of SDP relaxation problems are strictly and significantly less than that value. Some pieces of circumstantial evidences for the strange behaviours of SDP solvers are given. This result gives a warning to users of SDP relaxation method for POP to be careful in believing the results of the SDP solvers. We also demonstrate how SDPA-GMP, a multiple precision SDP solver developed by one of the authors, can deal with this situation correctly

Exploiting sparsity in primal-dual interior-point methods for semidefinite programming

The Helmberg-Rendl-Vanderbei-Wolkowicz/Kojima-Shindoh-Hara/Monteiro and Nesterov-Todd search directions have been used in many primal-dual interior-point methods for semidefinite programs. This paper proposes an efficient method for computing the two directions when the semidefinite program to be solved is large scale and sparse.