Influence of cross-sectional configuration on the synchronization of Kármán vortex shedding with the cylinder oscillation

The influence of cross-sectional configuration of a cylindrical body on the lock-in phenomenon of Karman vortex shedding was investigated using a mechanical oscillator for cross-flow oscillation of the cylinder. A circular, a semi-circular and a triangular cylinder with an equal height were used as test cylinders to see the effect of the movement of the separation point. The lock-in criteria accounting for the spanwise coherency of the Karman vortex were discussed based on the experimental data under a fixed Reynolds number of around 3500. The lock-in region on the plane of non-dimensional cylinder frequency and the non-dimensional amplitude was almost the same for all of the cylinders in spite of differences in the range of the separation point movement. The minimum value of non-dimensional threshold amplitude for lock-in was much smaller than the value of 0.05 which was reported so far. Results obtained in this work imply that the movement of the separation point is a result of the lock-in phenomenon, rather than an essential cause

Suppression of Kármán vortex excitation of a circular cylinder by a second cylinder set downstream in cruciform arrangement

A new technique for suppressing the Kármán vortex excitation of an elastically supported cylinder placed in an otherwise uniform flow is presented in this paper. By placing an another cylinder downstream of it in a cruciform arrangement with a gap s between them, the oscillation of the upstream cylinder can be virtually eliminated in the range of s/d1 < 0.4, where d1 is the diameter of the upstream cylinder. Compared with conventional techniques, this possesses the following advantages: i) it is unnecessary to change the shape of the oscillating body or remodel its supporting structure, and ii) the flow approaching the upstream body is practically undisturbed

Development of robust velocimeter for natural water flow monitoring

The ring-velocimeter coupled with a hot wire/film probe was developed and has been applied to wind and water tunnel experiments in Fluids Engineering Laboratory of Nagaoka University of Technology. In this study, the hot-wire/film probe is replaced by a cantilever attached by a strain gauge to detect the drag acting on the ring. The vortex shedding frequency from the ring is determined from the drag fluctuation by applying the spectrum analysis, and the flow velocity in turn since it is proportional with the vortex shedding frequency. This technique for flow velocity measurement is robust in the sense that it is strong against the noise or decay of the detected signal since the dominant frequency is insensitive to such disturbances, and that the detecting probe is strong against the contaminants or particles/objects carried by the fluid. These advantages, together with its simple and cheap characteristics, make it possible to apply to natural water flow with severe conditions

Canary in Twitter Mine: Collecting Phishing Reports from Experts and Non-experts

The rise in phishing attacks via e-mail and short message service (SMS) has not slowed down at all. The first thing we need to do to combat the ever-increasing number of phishing attacks is to collect and characterize more phishing cases that reach end users. Without understanding these characteristics, anti-phishing countermeasures cannot evolve. In this study, we propose an approach using Twitter as a new observation point to immediately collect and characterize phishing cases via e-mail and SMS that evade countermeasures and reach users. Specifically, we propose CrowdCanary, a system capable of structurally and accurately extracting phishing information (e.g., URLs and domains) from tweets about phishing by users who have actually discovered or encountered it. In our three months of live operation, CrowdCanary identified 35,432 phishing URLs out of 38,935 phishing reports. We confirmed that 31,960 (90.2%) of these phishing URLs were later detected by the anti-virus engine, demonstrating that CrowdCanary is superior to existing systems in both accuracy and volume of threat extraction. We also analyzed users who shared phishing threats by utilizing the extracted phishing URLs and categorized them into two distinct groups - namely, experts and non-experts. As a result, we found that CrowdCanary could collect information that is specifically included in non-expert reports, such as information shared only by the company brand name in the tweet, information about phishing attacks that we find only in the image of the tweet, and information about the landing page before the redirect

A Case Control Association Study and Cognitive Function Analysis of Neuropilin and Tolloid-Like 1 Gene and Schizophrenia in the Japanese Population

BACKGROUND: Using a knock-out mouse model, it was shown that NETO1 is a critical component of the NMDAR complex, and that loss of Neto1 leads to impaired hippocampal long term potentiation and hippocampal-dependent learning and memory. Moreover, hemizygosity of NETO1 was shown to be associated with autistic-like behavior in humans. PURPOSE OF THE RESEARCH: We examined the association between schizophrenia and the neuropilin and tolloid-like 1 gene (NETO1). First, we selected eight single nucleotide polymorphisms (SNPs) within the NETO1 locus, based on the Japanese schizophrenia genome wide association study (JGWAS) results and previously conducted association studies. These SNPs were genotyped in the replication sample comprised of 963 schizophrenic patients and 919 healthy controls. We also examined the effect of associated SNPs on scores in the Continuous Performance Test and the Wisconsin Card Sorting Test Keio version (schizophrenic patients 107, healthy controls 104). RESULTS: There were no significant allele-wise and haplotype-wise associations in the replication analysis after Bonferroni correction. However, in meta-analysis (JGWAS and replication dataset) three association signals were observed (rs17795324: p = 0.028, rs8098760: p = 0.017, rs17086492: p = 0.003). These SNPs were followed up but we could not detect the allele-specific effect on cognitive performance measured by the Continuous performance test (CPT) and Wisconsin Card Sorting test (WCST). MAJOR CONCLUSIONS: We did not detect evidence for the association of NETO1 with schizophrenia in the Japanese population. Common variants within the NETO1 locus may not increase the genetic risk for schizophrenia in the Japanese population. Additionally, common variants investigated in the current study did not affect cognitive performance, as measured by the CPT and WCST

Effects of Green Tea Fractions on Oxygen-Induced Retinal Neovascularization in the Neonatal Rat

This study aimed to investigate the preventive effects of green tea fractions (GTFs) on rat model of oxygen-induced retinopathy (OIR). Neonatal Sprague-Dawley rats were exposed to daily cycles of 80% oxygen (20.5 h), ambient air (0.5 h), and progressive return to 80% oxygen (3 h) until postnatal day 12 (P12), then the rats were placed in ambient air until P18. The green tea was fractionated by DM-A50, DM-W, M-B, and M-W. The rats were treated once daily from P6 to P17 by gastric gavage of GTFs (0.05 or 0.01 g/ml) or distilled water (DW) at 50 µl/10 g body weight. On P18, the rats were sacrificed and the retinal samples were collected. The retinal neovascularization (NV) was scored and avascular areas (AVAs) were measured as a % of total retinal area (%AVAs) in ADPase stained retinas. The NV scores in 0.01 g/ml M-W were significantly lower than those in DW. The %AVAs in 0.05 g/ml DM-A50 and in 0.05 g/ml and 0.01 g/ml M-W were significantly lower than those in DW. There were less catechins, and less caffeine in M-W fraction compared with other GTFs, suggesting components of green tea except for catechins and caffeine might suppress the neovascularization in rat model of OIR

Common Variants in MAGI2 Gene Are Associated with Increased Risk for Cognitive Impairment in Schizophrenic Patients

Schizophrenia is a complex psychiatric disorder characterized by positive symptoms, negative symptoms, and cognitive impairment. MAGI2, a relatively large gene (∼1.5 Mbps) that maps to chromosome 7q21, is involved in recruitment of neurotransmitter receptors such as AMPA- and NMDA-type glutamate receptors. A genetic association study designed to evaluate the association between MAGI2 and cognitive performance or schizophrenia has not been conducted. In this case-control study, we examined the relationship of single nucleotide polymorphism (SNP) variations in MAGI2 and risk for schizophrenia in a large Japanese sample and explored the potential relationships between variations in MAGI2 and aspects of human cognitive function related to glutamate activity. Based on the result of first schizophrenia genome-wide association study in a Japanese population (JGWAS), we selected four independent SNPs and performed an association study using a large independent Japanese sample set (cases 1624, controls 1621). Wisconsin Card Sorting Test (WCST) was used to evaluate executive function in 114 cases and 91 controls. We found suggestive evidence for genetic association of common SNPs within MAGI2 locus and schizophrenia in Japanese population. Furthermore in terms of association between MAGI2 and cognitive performance, we observed that genotype effect of rs2190665 on WCST score was significant (p = 0.034) and rs4729938 trended toward significance (p = 0.08). In conclusion, although we could not detect strong genetic evidence for association of common variants in MAGI2 and increased schizophrenia risk in a Japanese population, these SNPs may increase risk of cognitive impairment in schizophrenic patients