Effects of T-S wave amplitude on the control of boundary layer transition by streaks

The effects of streaks on boundary layer transition depend on the initial amplitude of T-S waves introduced to excite the transition. This problem was studied in a flat-plate boundary layer in water tunnel by using hydrogen bubble method. Three T-S wave initial amplitudes were tested. The results show that both narrow and wide-spacing streaks depress the transition excited by T-S waves with lower initial amplitude. However, when transition is excited by T-S waves of higher initial amplitude, the narrow-spacing streaks depress the transition, while the wide-spacing streaks promote the transition. Futrther the underlying mechanisms were also analyzed.

SOME CHARACTERISTICS OF LOW-SPEED STREAKS UNDER SHEARED AIR-WATER INTERFACES

The characteristics of low-speed fluid streaks occurring under sheared air-water interfaces were examined by means of hydrogen bubble visualization technique. A critical shear condition under which the streaky structure first appears was determined to be u(tau) approximate to 0.19 cm/s. The mean spanwise streak spacing increases with distance from the water surface owing to merging and bursting processes, and a linear relationship describing variation of non-dimensional spacing <(<lambda>+)over bar> versus y(+) was found essentially independent of shear stress on the interface. Values of <(<lambda>+)over bar>, however, are remarkably smaller than their counterparts in the near-wall region of turbulent boundary layers. Though low-speed streaks occur randomly in time and space, the streak spacing exhibits a lognormal probability distribution behavior. A tentative explanation concerning the formation of streaky structure is suggested, and the fact that <(<lambda>+)over bar> takes rather smaller values than that in wall turbulence is briefly discussed.

Numerical study on evolution of subharmonic varicose low-speed streaks in turbulent channel flow

The evolution of two spanwise-aligned low-speed streaks in a wall turbulent flow, triggered by the instability of the subharmonic varicose （SV） mode, is studied by a direct numerical simulation （DNS） method in a small spatial-periodic channel. The results show that the SV low-speed streaks are self-sustained at the early stage, and then transform into subharmonic sinuous （SS） low-speed streaks. Initially, the streamwise vortex sheets are formed by shearing, and then evolve into zigzag vortex sheets due to the mutual induction. As the intensification of the SV low-speed streaks becomes prominent, the tilted streamwise vortex tubes and the V-like streamwise vortex tubes can be formed simultaneously by increasing ＋~. When the SV low-speed streaks break down, new zigzag streamwise vortices will be generated, thus giving birth to the next sustaining cycle of the SV low-speed streaks. When the second breakdown happens, new secondary V-like streamwise vortices instead of zigzag streamwise vortices will be generated. Because of the sweep motion of the fluid induced by the secondary V-like streamwise vortices, each decayed low-speed streak can be divided into two parts, and each part combines with the part of another streak, finally leading to the formation of SS low-speed streaks.

Numerical simulation on evolution of subharmonic low-speed streaks in minimal channel turbulent flow

The evolution of low-speed streaks in the turbulent boundary layer of the minimum channel flow unit at a low Reynolds number is simulated by the direct numer- ical simulation （DNS） based on the standard Fourier-Chebyshev spectral method. The subharmonic sinuous （SS） mode for two spanwise-aligned low-speed streaks is excited by imposing the initial perturbations. The possibilities and the physical realities of the turbulent sustaining in the minimal channel unit are examined. Based on such a flow field environment, the evolution of the low-speed streaks during a cycle of turbulent sus- taining, including lift-up, oscillation, and breakdown, is investigated. The development of streamwise vortices and the dynamics of vortex structures are examined. The results show that the vortices generated from the same streak are staggered along the streamwise direction, while the vortices induced by different streaks tilt toward the normal direction due to the mutual induction effect. It is the spatial variations of the streamwise vortices that cause the lift-up of the streaks. By resolving the transport dynamics of enstrophy, the strength of the vortices is found to continuously grow in the logarithmic layer through the vortex stretching mechanism during the evolution of streaks. The enhancement of the vortices contributes to the spanwise oscillation and the following breakdown of the low-speed streaks.

A new kind of hairpin-like vortical structure induced by cross-interaction of sinuous streaks in turbulent channel

This work is motivated by previous experimental and numerical studies which reveal that the hairpin vortex could be formed by the interaction between spanwise adjacent low-speed streaks. To prove that such an interaction mechanism is still applicable in the normal direction, two sinuous low-speed streaks with the same streamwise phase are set to be in the upper half and bottom half of a small size channel, respectively, and their evolution and interaction are investigated by direct numerical simulation. A new kind of hairpin-like vortical structure, distributed in the normal direction and straddled across both halves of the channel, is found during the cross-interaction process of the low-speed streaks. The influence of such a normal-distributed hairpin-like vortex （NHV） on the turbulent statistical regularity is also revealed. It is observed that the NHV can lead to a sudden surge of wall skin friction, but the value of the normal velocity as well as the streamwise and spanwise vorticity sharply decrease to zero in the center of the channel.

Choroidal neovascularization and angioid streaks in pseudoxanthoma elasticum

AIM: To report a case of pseudoxanthoma elasticum (PXE) in a 48 year old woman that presented with bilateral blurry vision. METHODS: A case report RESULTS: A 48-year-old woman presented with bilateral blurry vision and right eye metamorphopsia. The patient had a history of angioid streaks in the left eye ten years ago for which she had received laser surgery and had poor residual vision. Visual acuity was 20/60 in the right eye and count fingers at 6 feet in the left. Fundus examination showed subretinal hemorrhage and macular thickening on the right and a disciform macular scar with focal atrophic pigment epithelial lesions on the left. Both eyes had angioid streaks and peau d’orange pigmentary pattern of the retina. External examination showed several, yellow skin papules and plaques on the lateral and posterior neck, as well as prominent mental creases. Pathologic examination of skin biopsy confirmed the diagnosis of PXE, showing calcium deposition and fragmented, clumped elastic fibers in the deep reticular dermis. She responded well to intravitreal bevacizumab injections and visual acuity improved to 20/25 OD. Preventative care was emphasized and the patient was referred to cardiology, gastroenterology and human genetics for counseling. CONCLUSION: PXE is a multisystem disorder affecting the dermatologic, ocular, and cardiovascular systems. Ophthalmic findings of angioid streaks and choroidal neovascularization in the presence of stereotypical skin changes and prominent mental creases should prompt evaluation for PXE.

Standardization of Winning Streaks in Sports

This research provides some metrics to better summarize streaks in sporting events with binary outcomes. In sporting events, information is often lost when “statistics” are presented regarding “streaks,” and whether or not certain teams or players have been recently been successful or unsuccessful. This usually leads to the presentation of metrics with no common baseline. This particular research effort provides statistics to capture the information regarding recent success or lack thereof, in a more standardized manner. To illustrate the presented metrics, data from the 2016 seasons for the American sports leagues National Basketball Association and Major League Baseball are used in an attempt to standardize streaks.

Angioid Streaks in Psuedoxanthoma Elasticum

Pseudoxanthoma elasticum (PXE) is a hereditary disorder that affects primarily the elastic tissues of skin, eyes and blood vessels. Its estimated prevalence is thought to be 1:25,000 - 100,000. PXE patients also carry an increased risk for cardiovascular and gastrointestinal diseases. Early diagnosis can play a crucial role in preventing early loss of vision and systemic complications in these patients however despite having characteristic clinical features;it is still to a large extent being under-diagnosed. Here we present two cases of PXE with reduced vision.

Using Sports Wagering Markets to Evaluate and Compare Team Winning Streaks in Sports

Point spreads and money lines from sports wagering markets are used to evaluate the impressiveness of team streaks. Sports wagering data have previously been useful in assessing competitive balance in sports. Our approach was motivated by the amount of media scrutiny that accompanied the winning streak of the NBA’s Miami Heat and the point streak of the NHL’s Chicago Blackhawks which occurred simultaneously for the most part in 2013. The topic came to the forefront again with the 2014-2015 winning streak of the Atlanta Hawks. Three streaks are highlighted in our paper. The length of the streaks, the quality of the competition, injuries, and a variety of other factors were mentioned in the media but the discussion was limited to subjective opinions as no way of properly weighing relative influence of the factors was identified. Wagering markets provide an excellent source of information for making these judgments. Several complementary measures are described and the most impressive team streaks within and across professional baseball, basketball, football, and ice hockey are identified.

Attosecond ionization time delays in strong-field physics

Electronic processes within atoms and molecules reside on the timescale of attoseconds. Recent advances in the laserbased pump-probe interrogation techniques have made possible the temporal resolution of ultrafast electronic processes on the attosecond timescale, including photoionization and tunneling ionization. These interrogation techniques include the attosecond streak camera, the reconstruction of attosecond beating by interference of two-photon transitions, and the attoclock. While the former two are usually employed to study photoionization processes, the latter is typically used to investigate tunneling ionization. In this review, we briefly overview these timing techniques towards an attosecond temporal resolution of ionization processes in atoms and molecules under intense laser fields. In particular, we review the backpropagation method, which is a novel hybrid quantum-classical approach towards the full characterization of tunneling ionization dynamics. Continued advances in the interrogation techniques promise to pave the pathway towards the exploration of ever faster dynamical processes on an ever shorter timescale.

Establishment of Reverse-transcription Loopmediated Isothermal Amplification Method for Detection of Wheat Streak Mosaic Virus

A reverse-transcription loop-mediated isothermal amplification （RT-LAMP） method was established for the detection of wheat streak mosaic virus （WSMV）. Ac-cording to the conservative regions of the genes that encode the coat protein of WSMV, 2 pairs of primers were designed. Final y, the 1st pair of primers was select-ed through the specificity test. The sensitivity test showed the sensitivity of RT-LAMP method was 10 times higher than that of RT-PCR. In addition, the amplifica-tion of target gene could be judged visual y from the presence of fluorescence （cal-cein） in the final reaction system. The RT-LAMP method, established in this study, was rapid, easy, specific and sensitive. Moreover, it did not require sophisticated equip-ment. The RT-LAMP was suitable for the rapid detection of WSMV.

英语单词扩展对比记忆法

在英语学习中,常会遇到一些词,其前或其后加上一两个字母后,意思大不相同,学生容易将它们相混淆。若将它们放在一起记忆,既利于比较,又容易记住,现在举例如下: 1.arc,arch,archaeology arc弧,arch拱门,archaeology考古(学) 你可以这样记这些单词:先在墓室壁上画个arc,然后再开个arch,就可以进行archaeology了。 2.tact,tract,abstract。

Identification of a Resistance Gene bls1 to Bacterial Leaf Streak in Wild Rice Oryza rufipogon Griff

Bacterial leaf streak （BLS） of rice, caused by Xanthomonas oryzae pv. oryzicola （Xoc） is a worldwide destructive disease. Development of resistant varieties is considered to be one of the most effective and eco-friendly ways to control the disease. However, only a few genes/QTLs having resistance to BLS have been identified in rice until now. In the present study, we have identified and primarily mapped a BLS-resistance gene, blsl, from a rice line DP3, derived from the wild rice species Oryza rufipogon Griff. A BC2F2 （9311/DP3//9311） population was constructed to map BLS-resistance gene in the rice line DP3. The segregation of the resistant and susceptible plants in BCzFz in 1：3 ratio （Z2=0.009, Z20 05,1=3.84, P〉0.05）, suggested that a recessive gene confers BLS resistance in DP3. In bulked segregant analysis （BSA）, two SSR markers RM8116 and RM584 were identified to be polymorphic in resistant and susceptible DNA bulks. For further mapping the resistance gene, six polymorphic markers around the target region were applied to analyze the genotypes of the BC2F2 individuals. As a result, the BLS-resistant gene, designated as blsl, was mapped in a 4.0-cM region flanked by RM587 and RM510 on chromosome 6.

OsBGLU19 and OsBGLU23 regulate disease resistance to bacterial leaf streak in rice

β-Glucosidase belongs to the glycoside hydrolase I family,which is widely present in multiple species and responds to various biotic and abiotic stresses.In rice,whetherβ-glucosidase is involved in the interaction between plants and microorganisms is not clear.In this study,we found that the expression of several genes encodingβ-glucosidases,including OsBGLU19 and OsBGLU23,were upregulated after inoculation with Xanthomonas oryzae pv.oryzicola(Xoc)and downregulated after inoculation with X.oryzae pv.oryzae(Xoo).The respective insertion mutants of OsBGLU19 and OsBGLU23,bglu19 and bglu23,were more susceptible to Xoc infection.The expression of OsAOS2,a key gene in the jasmonic acid signal pathway,was dramatically downregulated after inoculation with Xoc in the bglu19 and bglu23 mutants.Simultaneously,the expression of downstream disease resistance-related genes,such as OsPR1a,OsPR5 and a key transcription factors OsWRKY72 were obviously downregulated.The resistance mediated by OsBGLU19 and OsBGLU23 to bacterial leaf streak is related to disease resistance-related genes above mentioned.

In-vitro antimicrobial activity of marine actinobacteria against multidrug resistance Staphylococcus aureus

Objective:To investigate the antibacterial aclivily of marine actinobacteria against multidrug resistance Staphylococcus aureus(MDRSA).Methods:Fifty one actinobacterial strains were isolated from salt pans soil,costal area in Kothapattanam,Ongole,Andhra Pradesh.Primary screening was done using cross-streak method against MDRSA.The bioaclive compounds are extracted from efficient actinobacteria using solvent extraction.The antimicrobial activity of crude and solvent extracts was perfomied using Kirby-Bauer method.MIC for ethyl acetate extract was determined by modified agar well diffusion method.The potent actinobacteria are identified using Nonomura key,Shirling and Gottlieb 1966 with Bergey's manual of determinative bacteriology.Results:Among the fifty one isolates screened for antibacterial activity,SRB25were found efficient against MDRSA.The ethyl acetate extracts showed high inhibition against test organism.MIC test was performed with the ethyl acetate extract against MDRSA and found to be 1 000μg/mL.The isolaled actinobacteria are identified as Streptomyces sp with the help of Nonomura key.Conclusions:The current investigation reveals that the marine actinobacteria from salt pan environment can be able to produce new drug molecules against drug resistant microorganisms.

The spatial-temporal evolution of coherent structures in log law region of turbulent boundary layer

The spatial-temporal evolution of coherent structures （CS） is significant for turbulence control and drag re- duction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was based on a time series of three-dimensional and three-component （3D-3C） velocity fields of the flat plate turbulent boundary layer （TBL） measured by a Tomographic and Time-resolved PIV （Tomo TRPIV） system. Using multi-resolution wavelet transform and conditional sampling method, we extracted the intrinsic topologies and found that the streak structures appear in bar-like patterns. Furthermore, we seized locations and velocity information of transient CS, and then calculated the propagation velocity of CS based on spatial-temporal cross-correlation scanning. This laid a foundation for further studies on relevant dynamics properties.

R2N: A Novel Deep Learning Architecture for Rain Removal from Single Image

Visual degradation of captured images caused by rainy streaks under rainy weather can adversely affect the performance of many open-air vision systems.Hence,it is necessary to address the problem of eliminating rain streaks from the individual rainy image.In this work,a deep convolution neural network(CNN)based method is introduced,called Rain-Removal Net(R2N),to solve the single image de-raining issue.Firstly,we decomposed the rainy image into its high-frequency detail layer and lowfrequency base layer.Then,we used the high-frequency detail layer to input the carefully designed CNN architecture to learn the mapping between it and its corresponding derained high-frequency detail layer.The CNN architecture consists of four convolution layers and four deconvolution layers,as well as three skip connections.The experiments on synthetic and real-world rainy images show that the performance of our architecture outperforms the compared state-of-the-art de-raining models with respects to the quality of de-rained images and computing efficiency.

Numerical and experimental study of wave shaper effects on detonation wave front

In the current study, streak camera was used to find concentricity of the assembly during detonation,investigate and compare shock front within the high explosive and behavior of the shock front on the surface of the liner, one containing wave shaper and the other without wave shaper. Streaks revealed that the whole assembly was concentric till the formation of the jet. Observed streaks vindicate the uniform propagation of shock front in both the cases. Results obtained for shock front velocities are in agreement with those obtained from simulations. In the presence of wave shaper higher shock front velocity was observed both in simulation and experiment. Simulation without wave-shaper showed that shock front struck the copper cone at grazing angle while in the presence of wave-shaper it struck at an angle of 125.

Study on local topology model of low/high streak structures in wall-bounded turbulence by tomographic time-resolved particle image velocimetry

The relationship between the in the logarithmic law （log-law） region of bursting event and the low/high-speed streak a turbulent boundary layer is investigated. A tomographic time-resolved particle image velocimetry （TRPIV） system is used to measure the instantaneous three-dimensional-three-component （3D-3C） velocity field. The momentum thickness based Reynolds number is about 2 460. The topological information in the log-law region is obtained experimentally. It is found that the existence of the quadrupole topological structure implies a three-pair hairpin-like vortex packet, which is in connection with the low/high-speed streak. An idealized 3D topological model is then proposed to characterize the observed hairpin vortex packet and low/high-speed streak.

Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus

We evaluated the effects of rice black streak dwarf virus （RBSDV）-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of white-backed planthopper （WBPH） in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, whereas the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes （dismutase, catalase and peroxidase） and detoxification enzymes （acetylcholinesterase, carboxylesterase and glutathione S-transferase） were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.