Ryo Kato

User Location Anonymization Method for Wide Distribution of Dummies

Advances in GPS (global positioning system) technologies have led to a variety of services utilizing the user’s location becoming available. Since location information may reveal private information, preserving location privacy has become a significant issue. To preserve this privacy, we have proposed a user location anonymization method that generates dummies on the basis of the user’s trajectory with pauses in movement. However, the previous work does not sufficiently satisfy users’ requirements for location privacy because the locations of the generated dummies tended to gather in a small area as time passed. In this paper, we propose a user location anonymization method that always keeps dummies’ locations in an area wide enough to anonymize the user’s location. Our method periodically distributes dummies by moving them to an area where there were fewer users and dummies. We simulated the user’s movement on a real map and verified that the proposed method was more effective than the previous one.

Near-field absorption imaging by a Raman nano-light source

In aperture-less near-field scanning optical microscopy (NSOM), when the apex of a sharp silicon nano-tip is illuminated with an incident laser, the Raman scattered signal from silicon creates a nano-light source with a wavelength the same as the LO phonon mode of silicon. This Raman scattered light can be absorbed by a sample placed under the tip and thus enables us to study the optical properties of the sample at the nano-scale through the absorption of silicon Raman scattered light. In this study, we demonstrate nano-scale absorption imaging by measuring the intensity of silicon Raman signals generated at the apex of a near-field probe under a platform of conventional NSOM. We used two incident lasers of different colors, which allowed the absorption properties of the sample to be observed independent of topography, revealing the inherent optical properties of the sample. The present results demonstrate the flexibility of aperture-less NSOM, not only for vibrational spectroscopies, such as tip-enhanced Raman spectroscopy, but also for electronic energy state analysis, which is achieved by monitoring the intensity of the Raman nano-light source rather than the Rayleigh scattering. This new method of near-field imaging can extend the potential applications of aperture-less NSOM.

Successful Endoscopic Treatment of Post-esophagectomy Refractory Reflux Using OverStitch: The First Clinical Case:

Aims: The reflux of duodeno-gastric contents into the remnant esophagus (gastric tube-esophageal reflux: GTER) is a significant issues in long-term esophageal cancer survivors after radical esophagectomy. We attempted endoscopic valve (funnel) creation for prevention for GTER using OverStitch endoscopic suturing system. Methods: The OverStitch was mounted onto a standard double-channel endoscope. Under general anesthesia, the funnel creation was attempted by placing semi-full thickness sutures on the gastric wall, at 3 cm distal to the primary esophago-gastric anastomosis. The postoperative outcomes were also evaluated. Results: In total, 4 sutures were needed and the operating time was 62 minutes without complication. The endoscopic and swallowing studies, as well as pH profile, were all improved postoperatively. The patient’s quality of life was dramatically improved with complete disappearance of night-time reflux in spine position. Conclusions: Endoscopic antireflux funnel creation was feasible and safe. This procedure may become a useful treatment for patients with severe GTER after esophagectomy.

Increased Tim-3+ T cells in PBMCs during nivolumab therapy correlate with responses and prognosis of advanced esophageal squamous cell carcinoma patients

The recent development of immune checkpoint inhibitors for many types of cancers has prompted us to identify markers that predict patients with clinical benefits. Several trials on nivolumab for the treatment of esophageal squamous cell carcinoma (ESCC) have been performed worldwide, and the identification of markers specific to ESCC is urgently needed. We conducted a clinical trial on nivolumab for advanced ESCC (JapicCTI-No.142422) and investigated markers using peripheral blood collected from 20 patients enrolled in our institute, including 1 with a complete response (CR), 5 with a partial response (PR), 6 with a stable disease (SD), and 8 with a progressive disease (PD) as clinical responses. The expression of surface molecules and cytokine production by T cells were analyzed using flow cytometry, and clinicopathological factors and general blood parameters were examined. Albumin, neutrophils, %Tim3, %OX40, %CD103, %CD45RA−CD27−, and IL-1b after the first cycle of nivolumab treatment, but not at baseline, distinguished CR/PR from SD/PD patients. When markers to distinguish longer survivors with nivolumab therapy were analyzed, changes in these levels between baseline and after the first cycle of nivolumab treatment, but not levels at each period, were indicative, similar to the tumor burden. Among them, elevations in %Tim-3+CD4 had a marked impact on survival rates. In conclusion, dynamic elevations in %Tim-3 in T cells in the early period of nivolumab therapy have potential as a marker for the clinical responses and prognosis of advanced ESCC patients.

Near-field visible light absorption imaging by Raman-nano-light source

We propose a new nano-imaging technique for intrinsic absorption properties of materials under a platform of conventional aperture-less near-field scanning optical microscopy (NSOM). In aperture-less NSOM, when a silicon nanotip is utilized and illuminated by the visible light instead of a metallic tip, Raman scattering of silicon from the tip apex can be obtained. Since the wavelength of this Raman scattered light is shifted to 520cm-1 from the one of the excitation light, far-field background signal excited by the diffraction limited focus spot of the incident light, which is one of the major problems in aperture-less NSOM, can be avoided. When the silicon nano-tip is on the sample and illuminated, the Raman signal of silicon can be partially absorbed by the sample while passing through it, so that measuring the intensity of the Raman signal of silicon enables us to observe the absorption behavior of the sample at nano-scale. Because the absorbance of light is dependent on the absorption coefficient of the sample as well as its sample topography, it is needed to eliminate the effect of the sample topography from the absorption measurement to technically evaluate the absorption coefficient of the sample. For this purpose, we simultaneously employed two different incident lasers and utilized absorbance ratio between two wavelengths to monitor the absorption coefficient of the sample. As an example, we demonstrated that two types of carbon nanotubes, which have different absorption properties, could be clearly distinguished with nano-scale resolution by our technique.