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Inspired by the forward swimming of long-tailed crustaceans, we study an underwater propulsion mechanism for a swimming body with multiple rigid paddles attached underneath undergoing cycles of power and return strokes with a constant phase-difference between neighboring paddles, a phenomenon known as metachronal propulsion. To study how inter-paddle phase-difference affects flux production, we develop a computational fluid dynamics model and a numerical algorithm based on the immersed boundary method, which allows us to simulate metachronal propulsion at Reynolds numbers (RE) ranging from close to 0 to about 100. Our main finding is that the highest average flux is generated when nearest-neighbor paddles maintain an approximate 20%-25% phase-difference with the more posterior paddle leading the cycle; this result is independent of stroke frequency across the full range of RE considered here. We also find that the optimal paddle spacing and the number of paddles depend on RE; we see a qualitative transition in the dynamics of flow generated by metachronal propulsion as RE rises above 80. Roughly speaking, in terms of average flux generation, a tight paddle spacing is preferred when RE is less than 10, but a wider spacing becomes clearly favored when RE is close to or above 100. In terms of efficiency of flux generation, at RE 0.1 the maximum efficiency occurs at two paddles, and the efficiency decreases as the number of paddles increases. At RE 100 the efficiency increases as the number of paddles increases, and it appears to saturate by eight paddles, whereas using four paddles is a good tradeoff for both low and intermediate RE.

Ambient air pollutants have been reported to induce oxidative stress based inflammatory responses in humans and experimental animals. However, most of these reports describe the actions of the particulate phase of ambient and exhaust samples. We describe here results of studies investigating the actions of the vapor phase of ambient air samples collected in the midtown area of Los Angeles on human bronchial epithelial BEAS-2B cells using DNA microarray analysis. Among 26 genes whose expression increased fourfold or more, four genes were associated with detoxifying genes regulated by the transcription factor Nrf2. Consistent with these results, the vapor samples activate the Nrf2-ARE pathway, resulting in up-regulation of heme oxygenase-1 (HO-1), glutamate cysteine ligase modifier subunit, and cystine transporter (xCT) mRNA and proteins. No appreciable increases in pro-inflammatory genes were observed. These results suggest that ambient vapor samples activate the Nrf2-ARE pathway but not an inflammatory response. Also, treatment of the vapor samples with glutathione resulted in reduction in the Nrf2 activation and HO-1 induction, suggesting that electrophiles in vapor samples contribute to this Nrf2-dependent antioxidant or adaptive response.

Ryosuke Kitahata,1 Shinichiro Nakajima,1–4 Hiroyuki Uchida,1,3 Tetsu Hayashida,5 Maiko Takahashi,5 Shintaro Nio,1 Jinichi Hirano,1 Maki Nagaoka,1 Takefumi Suzuki,1 Hiromitsu Jinno,6 Yuko Kitagawa,5 Masaru Mimura1 1Psychopharmacology Research Program, Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan; 2Multimodal Imaging Group – Research Imaging Centre, 3Geriatric Mental Health Division, Centre for Addiction and Mental Health, 4Department of Psychiatry, University of Toronto, Toronto, Canada; 5Department of Surgery, School of Medicine, Keio University, 6Department of Surgery, School of Medicine, Teikyo University, Tokyo, Japan Purpose: The purpose of the study was to evaluate subjective (self-rated), family-rated, and objective (researcher-rated) cognitive functions in patients with breast cancer after chemotherapy.Method: We conducted a prospective study to trace self-rated cognitive functions in 30 patients with breast cancer at the completion of chemotherapy (T0) and 6 months later (T1). Subjective cognitive functions were assessed with Cognitive Failures Questionnaire (CFQ), Dysexecutive Questionnaire (DEX-S), and Everyday Memory Checklist (EMC-S) for attention, executive function, and episodic memory, respectively. Their family members also completed DEX-I and EMC-I for executive function and episodic memory, respectively. We also examined objective cognitive functions. Self-rated cognitive functions were compared with the normative data. They were compared between T0 and T1. We calculated correlation coefficients between self-rated and other cognitive functions.Results: At T0, 6 (20.0%) and 2 (6.7%) participants showed higher DEX-S and EMC-S scores than the normative data, respectively, while no participant had abnormal CFQ scores. At T1, DEX-S and EMC-S scores were normalized in 3 (50.0%) and 2 (100.0%) participants, respectively. No participant showed increases in CFQ scores. No changes were found in objective cognitive functions from T0 to T1. DEX-S and DEX-I or EMC-S and EMC-I scores were correlated at both T0 and T1, which did not survive multiple corrections. There was no association between subjective and objective cognitive functions.Conclusion: Impairments in subjective cognition may be transient after chemotherapy in patients with breast cancer. Furthermore, patients and their families appear to share similar prospects on their cognitive functions. Keywords: breast cancer, chemotherapy, subjective cognitive functions