Temperature dependence of ferroelectric properties and the activation energy of polarization reversal in (Pr,Mn)-codoped BiFeO3 thin films

We applied Vopsaroiu\u27s model to (Bi,Pr)(Fe,Mn)O3 (BPFM) and Pb(Zr,Ti)O3 (PZT) ferroelectric thin films fabricated by chemical solution deposition. The temperature dependences of the saturation polarization and the coercive field were measured in a low-temperature region from 100 to 200K. The saturation polarizations of BPFM thin films decreased on decreasing the measurement temperature due to the polarization pinning effect, while that of PZT thin film was almost unchanged over the temperature region. The coercive fields of all the thin films were increased linearly on decreasing the measurement temperature. The activation energies for polarization reversal in as-grown BPFM, postannealed BPFM, and PZT thin films were 1.18, 1.25, and 0.95eV, respectively. These results indicate that BPFM thin films have large activation energies for polarization reversal compared with PZT thin films. In addition, the postannealed BPFM thin film has a larger activation energy than the as-grown BPFM thin film. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Impact of HBV Infection on Outcomes of Direct-Acting Antiviral Therapy of Chronic Hepatitis C

Background: Most clinical trials of direct-acting antiviral (DAA) therapy for hepatitis C virus (HCV) infection have excluded hepatitis B virus (HBV) coinfection, and little is known about the effects of DAA on chronic hepatitis C patients with HBV coinfection. Recent studies have reported that DAA therapy for HCV can also cause HBV reactivation in patients with HBV and HCV coinfection. The aim of this study was to assess the effects of DAA on sustained virologic response (SVR) and HBV reactivation in patients with chronic hepatitis C. Methods: Participants comprised 199 chronic hepatitis C patients who received DAA therapy (96 men, 103 women; mean age, 66.7 ± 12.0 years). Results: Twelve patients were coinfected with HCV and HBV. Sixty patients were HBV surface antigen negative but positive for hepatitis B core antibody and/or hepatitis B surface antibody, and one hundred and twenty-seven patients had not been exposed to HBV. Rates of SVR in HBV and HCV coinfected patients, HBV prior infection, and no exposure to HBV were 100, 95, and 97%, respectively. Significant differences were seen between each group. No case showed HBV reactivation. Conclusions: DAA treatments were effective in patients with HBV coinfection or HBV prior infection, as well as HCV monoinfection. As the number of cases was small, we still suggest caution regarding HBV reactivation in HCV and HBV coinfected patients undergoing treatment with DAA

Calibration Method of Visual Parameters for See-Through Head-Mounted Display

It is expected that See-Through Head-Mounted Display (STHMD), which superimposes the virtual environment generated by computer graphics (CG) on the real world, can vividly execute various simulations and designs by using both of the real and virtual environment around us. In STHMDs, information given as a virtual environment has to exactly match with the real environment, because both environments are visible. This is one of the problems to be solved for practical use. Particularly for matching of locations and size between real and virtual objects, disaccordance is likely to occur between the world coordinate of the real environment where the user of STHMD actually exists and that of the virtual environment described as parameters of CG, which directly causes displacement of locations where virtual objects are superimposed. This must be calibrated so that the virtual environment is superimposed properly. Among causes of such errors, we focused both on systematic errors of visual parameters caused in manufacturing process and differences between actual and supposed location of user\u27s eye on STHMD when in use. The former is required to be calibrated only once after the fabrication of STHMDs, whereas the latter has to be calibrated every time users start using STHMDs. We have proposed calibration methods which are suitable to properties of these causes of errors. In the method, the direct fitting of the virtual cursor drawn in the virtual environment onto targets in the real environment is performed. Then, based on the result of fitting, the least square method identifies values of the visual parameters which minimize differences between locations of virtual cursor in the virtual environment and targets in the real environment. Application of the method to the STHMD which we have made is also reported. The differences between the virtual cursor and targets in the real environment due to systematic errors caused in the manufacturing process were reduced to about 1 [mm] per target, which was less than one-thirtieth of that before the calibration. The differences between the virtual cursor and targets in the real environment due to the location of user\u27s eyes were also reduced about 2 [mm] per target, which was a half of that before the calibration. This result was well enough to prove the effectiveness of the calibration methods

Large or multiple pseudocysts can impede or complicate the nonsurgical treatment of pancreatolithiasis

Objectives: We aimed to determine when a coexisting pseudocyst was likely to complicate the nonsurgical treatment of pancreatolithiasis. Methods: We treated 165 patients with pancreatolithiasis nonsurgically between 1992 and 2020, including 21 with pseudocysts. Twelve patients had a single pseudocyst less than 60 mm in diameter. Pseudocysts in the other nine patients had diameters of at least 60 mm or were multiple. The locations of pseudocysts along the length of the pancreas varied from the area with stone involvement to the pancreatic tail. We compared the outcomes in these groups. Results: We found no significant differences in pain relief, stone clearance, stone recurrence, or the likelihood of adverse events between pseudocyst groups or between patients with vs without pseudocysts. However, 4 of 9 patients with large or multiple pseudocysts required transition to surgical treatment (44%) compared with 13 of 144 patients with pancreatolithiasis and no pseudocyst (9.0%) (P=0.006). Conclusions: Patients with smaller pseudocysts typically underwent nonsurgical stone clearance successfully with few adverse events, similar to findings in patients with pancreatolithiasis and no pseudocysts. Pancreatolithiasis complicated by large or multiple pseudocysts did not cause more adverse events but was more likely to require transition to surgery compared with pancreatolithiasis without pseudocysts. In patients with large or multiple pseudocysts, early transition to surgery should be considered when nonsurgical treatment is ineffective

Rigid foldability is NP-hard

In this paper, we show that the rigid-foldability of a given crease pattern using all creases is weakly NP-hard by a reduction from the partition problem, and that rigid-foldability with optional creases is NP-hard by a reduction from the 1-in-3 SAT problem. Unlike flat-foldabilty of origami or flexibility of other kinematic linkages, whose complexity originates in the complexity of the layer ordering and possible self-intersection of the material, rigid foldabilltiy from a planar state is hard even though there is no potential self-intersection. In fact, the complexity comes from the combinatorial behavior of the different possible rigid folding configurations at each vertex. The results underpin the fact that it is harder to fold from an unfolded sheet of paper than to unfold a folded state back to a plane, frequently encountered problem when realizing folding-based systems such as self-folding matters and reconfigurable robots