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The photovoltaic effect can occur without metal/semiconductor or semiconductor/semiconductor interfaces in materials with spontaneous electric polarization due to a lack of spatial inversion symmetry. This anomalous phenomenon is known as the bulk photovoltaic (BPV) effect owing to the shift current, which facilitates photoelectric conversion. Alpha-phase indium selenide (α-In2Se3) is a ferroelectric semiconductor with spontaneous electric polarization. Here, we report an experimental demonstration of the BPV effect in α-In2Se3 films along the out-of-plane direction by utilizing graphite films as transparent electrodes. A short-circuit current was detected under white light irradiation, and the sign was inverted upon inverting the direction of electric polarization, thus suggesting its origin to be the shift current, distinct from the effect occurring at the interface. The trend of BPV performances owing to the shift current with respect to the irradiated photon energy is consistent with the dependence of its absorption coefficient. The quantum efficiency of photoelectric conversion for α-In2Se3 along the out-of-plane direction was a few orders of magnitude greater than that of conventional and layered ferroelectric materials and was comparable to that of low-dimensional interface structures and strained two-dimensional materials. Our results pave the way for the innovative design of photoelectric conversion devices. [ABSTRACT FROM AUTHOR]

Purpose: In recent years, deep learning–based image processing has emerged as a valuable tool for medical imaging owing to its high performance. However, the quality of deep learning–based methods heavily relies on the amount of training data; the high cost of acquiring a large data set is a limitation to their utilization in medical fields. Herein, based on deep learning, we developed a computed tomography (CT) modality conversion method requiring only a few unsupervised images. Methods: The proposed method is based on cycle‐consistency generative adversarial network (CycleGAN) with several extensions tailored for CT images, which aims at preserving the structure in the processed images and reducing the amount of training data. This method was applied to realize the conversion of megavoltage computed tomography (MVCT) to kilovoltage computed tomography (kVCT) images. Training was conducted using several data sets acquired from patients with head and neck cancer. The size of the data sets ranged from 16 slices (two patients) to 2745 slices (137 patients) for MVCT and 2824 slices (98 patients) for kVCT. Results: The required size of the training data was found to be as small as a few hundred slices. By statistical and visual evaluations, the quality improvement and structure preservation of the MVCT images converted by the proposed model were investigated. As a clinical benefit, it was observed by medical doctors that the converted images enhanced the precision of contouring. Conclusions: We developed an MVCT to kVCT conversion model based on deep learning, which can be trained using only a few hundred unpaired images. The stability of the model against changes in data size was demonstrated. This study promotes the reliable use of deep learning in clinical medicine by partially answering commonly asked questions, such as "Is our data sufficient?" and "How much data should we acquire?" [ABSTRACT FROM AUTHOR]

Background: The efficacy of a hydrogel spacer in stereotactic body radiotherapy (SBRT) has not been clarified. We evaluated the safety and efficacy of SBRT in combination with a hydrogel spacer for prostate cancer.Methods: This is a prospective single-center, single-arm phase II study. Prostate cancer patients without lymph node or distant metastasis were eligible. All patients received a hydrogel spacer insertion, followed by SBRT of 36.25 Gy in 5 fractions with volumetric modulated arc therapy. The primary endpoint was physician-assessed acute gastrointestinal (GI) toxicity within 3 months. The secondary endpoints were physician-assessed acute genitourinary (GU) toxicity, patient-reported outcomes evaluated by the EPIC and FACT-P questionnaires, and dosimetric comparison. We used propensity score-matched analyses to compare patients with the hydrogel spacer with those without the spacer. The historical data of the control without a hydrogel spacer was obtained from our hospital's electronic records.Results: Forty patients were enrolled between February 2017 and July 2018. A hydrogel spacer significantly reduced the dose to the rectum. Grade 2 acute GI and GU toxicity occurred in seven (18%) and 17 (44%) patients. The EPIC bowel and urinary summary score declined from the baseline to the first month (P < 0.01, < 0.01), yet it was still significantly lower in the third month (P < 0.01, P = 0.04). For propensity score-matched analyses, no significant differences in acute GI and GU toxicity were observed between the two groups. The EPIC bowel summary score was significantly better in the spacer group at 1 month (82.2 in the spacer group and 68.5 in the control group).Conclusions: SBRT with a hydrogel spacer had the dosimetric benefits of reducing the rectal doses. The use of the hydrogel spacer did not reduce physician-assessed acute toxicity, but it improved patient-reported acute bowel toxicity.Trial Registration: Trial registration: UMIN-CTR, UMIN000026213. Registered 19 February 2017, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000029385 . [ABSTRACT FROM AUTHOR]

Purpose: Cone‐beam computed tomography (CBCT) offers advantages over conventional fan‐beam CT in that it requires a shorter time and less exposure to obtain images. However, CBCT images suffer from low soft‐tissue contrast, noise, and artifacts compared to conventional fan‐beam CT images. Therefore, it is essential to improve the image quality of CBCT. Methods: In this paper, we propose a synthetic approach to translate CBCT images with deep neural networks. Our method requires only unpaired and unaligned CBCT images and planning fan‐beam CT (PlanCT) images for training. The CBCT images and PlanCT images may be obtained from other patients as long as they are acquired with the same scanner settings. Once trained, three‐dimensionally reconstructed CBCT images can be directly translated into high‐quality PlanCT‐like images. Results: We demonstrate the effectiveness of our method with images obtained from 20 prostate patients, and provide a statistical and visual comparison. The image quality of the translated images shows substantial improvement in voxel values, spatial uniformity, and artifact suppression compared to those of the original CBCT. The anatomical structures of the original CBCT images were also well preserved in the translated images. Conclusions: Our method produces visually PlanCT‐like images from CBCT images while preserving anatomical structures. [ABSTRACT FROM AUTHOR]

We conducted a feasibility study to predict malignant glioma grades via radiomic analysis using contrast-enhanced T1-weighted magnetic resonance images (CE-T1WIs) and T2-weighted magnetic resonance images (T2WIs). We proposed a framework and applied it to CE-T1WIs and T2WIs (with tumor region data) acquired preoperatively from 157 patients with malignant glioma (grade III: 55, grade IV: 102) as the primary dataset and 67 patients with malignant glioma (grade III: 22, grade IV: 45) as the validation dataset. Radiomic features such as size/shape, intensity, histogram, and texture features were extracted from the tumor regions on the CE-T1WIs and T2WIs. The Wilcoxon–Mann–Whitney (WMW) test and least absolute shrinkage and selection operator logistic regression (LASSO-LR) were employed to select the radiomic features. Various machine learning (ML) algorithms were used to construct prediction models for the malignant glioma grades using the selected radiomic features. Leave-one-out cross-validation (LOOCV) was implemented to evaluate the performance of the prediction models in the primary dataset. The selected radiomic features for all folds in the LOOCV of the primary dataset were used to perform an independent validation. As evaluation indices, accuracies, sensitivities, specificities, and values for the area under receiver operating characteristic curve (or simply the area under the curve (AUC)) for all prediction models were calculated. The mean AUC value for all prediction models constructed by the ML algorithms in the LOOCV of the primary dataset was 0.902 ± 0.024 (95% CI (confidence interval), 0.873–0.932). In the independent validation, the mean AUC value for all prediction models was 0.747 ± 0.034 (95% CI, 0.705–0.790). The results of this study suggest that the malignant glioma grades could be sufficiently and easily predicted by preparing the CE-T1WIs, T2WIs, and tumor delineations for each patient. Our proposed framework may be an effective tool for preoperatively grading malignant gliomas. [ABSTRACT FROM AUTHOR]

Stereotactic body radiotherapy (SBRT) for centrally‑located lung tumors remains a challenge because of the increased risk of treatment‑related adverse events (AEs), and uncertainty around prescribing the optimal dose. The present study reported the results of central tumor SBRT with 56 Gy in 7 fractions (fr) at the University of Tokyo Hospital. A total of 35 cases that underwent SBRT with or without volumetric‑modulated arc therapy consisting of 56 Gy/7 fr for central lung lesions between 2010 and 2016 at the University of Tokyo Hospital were reveiwed. A central lesion was defined as a tumor within 2 cm of the proximal bronchial tree (RTOG 0236 definition) or within 2 cm in all directions of any critical mediastinal structure. Local control (LC), overall survival (OS), and AEs were investigated. The Kaplan‑Meier method was used to estimate LC and OS. AEs were scored per the Common Terminology Criteria for Adverse Events Version 4.0. Thirty‑five patients with 36 central lung lesions were included. Fifteen lesions were primary non‑small cell lung cancer (NSCLC), 13 were recurrences of NSCLC, and 8 had oligo‑recurrences from other primaries. Median tumor diameter was 29 mm. Eighteen patients had had prior surgery. At a median follow‑up of 13.1 months for all patients and 18.3 months in surviving patients, 22 patients had died, ten due to primary disease (4 NSCLC), while three were treatment‑related. The 1‑ and 2‑year OS were 57.3 and 40.4%, respectively, and median OS was 15.7 months. Local recurrence occurred in only two lesions. 1‑ and 2‑year LC rates were both 96%. Nine patients experienced grade ≥3 toxicity, representing 26% of the cohort. Two of these were grade 5, one pneumonitis and one hemoptysis. Considering the background of the subject, tumor control of our central SBRT is promising, especially in primary NSCLC. However, the safety of SBRT to central lung cancer remains controversial. [ABSTRACT FROM AUTHOR]

The low-energy effective theories for gapped insulators are classified by three parameters: permittivity ϵ, permeability μ, and theta angle θ. Crystals with periodic ϵ are known as photonic crystals. We here study the band structure of photons in a new type of crystals with periodic θ (modulo 2 π) in space, which we call the axion crystals. We find that the axion crystals have a number of new properties that the usual photonic crystals do not possess, such as the helicity-dependent mass gap and nonrelativistic gapless dispersion relation at small momentum. We briefly discuss possible realizations of axion crystals in condensed matter systems and high-energy physics. [ABSTRACT FROM AUTHOR]

In hadron resonances different structures of hadronic composite (molecule) and elementary (quark-intrinsic) natures may coexist. We sketch discussions based on our previous publications on the origin of hadron resonances (Hyodo et al. Phys. Rev. C 78:025203, ) on exotic $${\bar D (B)}$$ meson-nucleons as candidates of hadronic composites (Yamaguchi et al. Phys. Rev. D 84:014032, ) and on a for the coexistence/mixing of the two different natures (Nagahiro et al. Phys. Rev. D 83:111504, ). [ABSTRACT FROM AUTHOR]

We study the kaon photoproduction associated with the production of the ground state Λ. We investigate the role of K and K* exchange in the t-channel, which can be tested by the photon asymmetry in comparison with experimental data. We find a significant amount of contribution from the one-loop diagram induced by the gauged Wess-Zumino-Witten term for QCD anomaly. This enable us to use coupling constants which are determined in a microscopic way, unlike the previous phenomenological studies where the K* coupling strengths were treated as a free parameter. [ABSTRACT FROM AUTHOR]

β-N-Acetylgalactosaminidase [EC 3.2.1.53] was purified to homogeneity from the culture media of Bacillus sp. AT173-1. The enzyme has a molecular weight of 48,000 as estimated by SDS-PAGE under reducing conditions and an isoelectric point of 4.3. The enzyme requires dithiothreitol as an activator and is most active at pH 6.0. Analysis of its substrate specificity using 2-aminopyridine-labeled oligosaccharides as substrates revealed the enzyme specifically hydrolyzes β-N-acetylgalactosaminyl linkages of GalNAcβ1-4Galβ1-4Glc, GalNAcβ1-3Galα1-4Galβ1-4Glc, and N-glycans terminating with β-N-acetylga-lactosamine residues but not those with β-N-acetylglucosamine residues. The enzyme is thus a novel β-N-acetylgalactosaminidase with practically no β-N-acetylglucosamin-idase activity. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]