Influence Estimation for Generative Adversarial Networks

Identifying harmful instances, whose absence in a training dataset improves model performance, is important for building better machine learning models. Although previous studies have succeeded in estimating harmful instances under supervised settings, they cannot be trivially extended to generative adversarial networks (GANs). This is because previous approaches require that (1) the absence of a training instance directly affects the loss value and that (2) the change in the loss directly measures the harmfulness of the instance for the performance of a model. In GAN training, however, neither of the requirements is satisfied. This is because, (1) the generator's loss is not directly affected by the training instances as they are not part of the generator's training steps, and (2) the values of GAN's losses normally do not capture the generative performance of a model. To this end, (1) we propose an influence estimation method that uses the Jacobian of the gradient of the generator's loss with respect to the discriminator's parameters (and vice versa) to trace how the absence of an instance in the discriminator's training affects the generator's parameters, and (2) we propose a novel evaluation scheme, in which we assess harmfulness of each training instance on the basis of how GAN evaluation metric (e.g., inception score) is expect to change due to the removal of the instance. We experimentally verified that our influence estimation method correctly inferred the changes in GAN evaluation metrics. Further, we demonstrated that the removal of the identified harmful instances effectively improved the model's generative performance with respect to various GAN evaluation metrics.Comment: Published as a conference paper at ICLR 2021 (Spotlight

Soybean-Derived Phosphatidylserine Improves Memory Function of the Elderly Japanese Subjects with Memory Complaints

Soybean-derived phosphatidylserine (Soy-PS) is a phosphatidylserine made from soybean lecithin by enzymatic reaction with L-serine. A double-blind, randomized controlled study was conducted to investigate the effects of Soy-PS on the cognitive functions of the elderly Japanese subjects with memory complaints. Seventy-eight elderly people with mild cognitive impairment (50–69 years old) were randomly allocated to take Soy-PS (100 mg, 300 mg/day) or placebo for 6 months. As a result, there was no difference in blood markers and vital signs during Soy-PS treatment and any side effect caused by Soy-PS treatment was not observed. Neuropsychological test scores were similarly increased in all groups including placebo group. However, in the subjects with relatively low score at baseline, the memory scores in PS treated groups were significantly increased against the baseline, while those of placebo group remained unchanged. And the memory improvements in Soy-PS-treated groups were mostly attributed to the increase in delayed verbal recall, a memory ability attenuated in the earliest stage of dementia. In conclusion, Soy-PS used in this study is considered as safety food ingredient and 6 months of Soy-PS supplementation could improve the memory functions of the elderly with memory complaints

Resection of Segments 4, 5 and 8 for a Cystic Liver Tumor Using the Double Liver Hanging Maneuver

To achieve complete anatomic central hepatectomy for a large tumor compressing surrounding vessels, transection by an anterior approach is preferred but a skillful technique is necessary. We propose the modified technique of Belghiti's liver hanging maneuver (LHM). The case was a 77-year-old female with a 6-cm liver cystic tumor in the central liver compressing hilar vessels and the right hepatic vein. At the hepatic hilum, the spaces between Glisson's pedicle and hepatic parenchyma were dissected, which were (1) the space between the right anterior and posterior Glisson pedicles and (2) the space adjacent to the umbilical Glisson pedicle. Two tubes were repositioned in each space and ‘double LHM’ was possible at the two resected planes of segments 4, 5 and 8. Cut planes were easily and adequately obtained and the compressed vessels were secured. Double LHM is a useful surgical technique for hepatectomy for a large tumor located in the central liver

Milk Replacers and Bovine Spongiform Encephalopathy in Calves, Japan

Milk Replacers and Bovine Spongiform Encephalopathy in Calves, Japa

Gluteal-fold adipofascial perforator flap transposition for rectourethral fistula reconstruction

If a rectourinary fistula does not close spontaneously, it requires surgical closure. We present our experience of rectourethral fistula reconstruction using a gluteal-fold perforator flap, resulting in a successful outcome. The patient was a 64-year-old man with prostate cancer who underwent radical prostatectomy. However, he developed rectourinary fistula, which required surgical closure. A dissection was undertaken to divide the fistula tract, and the rectal and urethral defect were closed. A 12.0×3.0 cm gluteal-fold adipofascial perforator flap was harvested and placed in the space between the rectum and urethra. The viability of lap was favourable, without infection or necrosis. The patient could walk the next day, and was discharged 2 weeks later without fecaluria or liquid stool. We conclude that the gluteal-fold adipofascial perforator flap offers excellent functional advantages in rectourethral fistula reconstruction with minimal morbidity at the donor site