Small informal meetings of two to four participants are very common in work environments. For this reason, a convenient way for recording and archiving these meetings is of great interest. In order to efficiently archive such meetings, an important task to address is to keep trace of "who talked when" during a meeting. This paper proposes a new multi-modal approach to tackle this speaker activity detection problem. One of the novelty of the proposed approach is that it uses a human tracker that relies on scanning laser range finders (LRFs) to localize the participants. This choice is especially relevant for robotic applications as robots are often equipped with LRFs for navigation purpose. In the proposed system, a table top microphone array in the center of the meeting room acquires the audio data while the LRF based human tracker monitors the movement of the participants. Then the speaker activity detection is performed using Gaussian mixture models that were trained before hand. An experiment reproducing a meeting configuration demonstrates the performance of the system for speaker activity detection. In particular, the proposed hands free system maintains an good level of performance compared to the use of close talking microphone while participants are simultaneously speaking.

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Abstract. Esophageal squamous cell carcinoma (SCC) is one of the biological malignant tumors. Once a tumor invades the submucosa, an incidence of lymph node (LN) metastases is very high, thus resulting in poor survival. Recently, chemokines have been reported to play an important role in organspecific metastases in several malignancies. In particular, CCR7 has been reported to be associated with LN metastases by immunohistochemistry. However, there have been no studies of quantitative analyses of CCR7 mRNA expression on cancer cells. In this study, we investigated the clinical significance of the expression of CCR7 in the establishment of LN metastases of esophageal SCC. A series of 78 patients with esophageal SCC who underwent esophagectomy were consecutively selected. The expression of CCR7 mRNA from tumor tissue samples was analyzed by quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), and that from cancer cell samples collected using laser microdissection system was analyzed by qRT-PCR. Immunohistochemical staining of CCR7 was also performed. Although CCR7 mRNA expression in tumor tissues demonstrated no association with the LN metastases, that in cancer cells correlated with LN metastases (p<0.05) due to the fact that not only cancer cells but also infiltrating lymphocytes expressed CCR7 in tumor tissue. Multivariate logistic regression analysis revealed a high CCR7 expression in cancer cells to be an independent predictive factor for LN metastases. These results suggested that CCR7 expression might play an important role in establishing LN metastases in patients with esophageal SCC.

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