基于CBAM-U-Net的全二维气相色谱streak目标分割

针对全二维气相色谱(GC×GC)图像中streak目标具有低对比度特点而难以分割的问题,提出了一种基于CBAM-U-Net的图像分割模型,所提出的模型在U-Net网络模型的基础上,通过在网络特征提取阶段嵌入CBAM注意力机制,来增强目标区域的特征信息,保留更多图像纹理。基于企业提供的全二维气相色谱数据集的实验结果表明,所提出方法的Acc、CPA、Dice系数等方面均有所提升,分别达到了98.80%、73.50%和71.73%,说明融合CBAM注意力机制的U-Net模型能够有效提升对streak目标区域的分割精度。

OsBLS6.2:A rice bacterial leaf streak resistance gene identified by GWAS and RNA-seq

Bacterial leaf streak(BLS),caused by Xanthomonas oryzae pv.oryzicola(Xoc),is a bacterial disease affecting rice production in Asia and Africa,whose severity is expected to increase with climate change.Identification of new quantitative-trait loci(QTL)or resistance genes for BLS resistance is essential for developing resistant rice.A genome-wide association study to identify QTL associated with BLS resistance was conducted using phenotypic and genotypic data from 429 rice accessions.Of 47 QTL identified,45 were novel and two co-localized with previously reported QTL or genes conferring BLS resistance.qBLS6.2 on chromosome 6 explained the greatest phenotypic variation.Combined analysis of differential expression and annotations of predicted genes near qBLS6.2 based on haplotype and disease phenotype identified OsBLS6.2(LOC_Os06g02960)as a candidate gene for qBLS6.2.OsBLS6.2 knockout plants showed higher resistance to Xoc than wild-type plants.Many other candidate genes for resistance to Xoc were identified.

POD analysis of the instability mode of a low-speed streak in a laminar boundary layer

The instability of one single low-speed streak in a zero-pressure-gradient laminar boundary layer is investigated experimentally via both hydrogen bubble visualization and planar particle image velocimetry(PIV) measurement. A single low-speed streak is generated and destabilized by the wake of an interference wire positioned normal to the wall and in the upstream. The downstream development of the streak includes secondary instability and self-reproduction process, which leads to the generation of two additional streaks appearing on either side of the primary one. A proper orthogonal decomposition(POD) analysis of PIV measured velocity field is used to identify the components of the streak instability in the POD mode space: for a sinuous/varicose type of POD mode, its basis functions present anti-symmetric/symmetric distributions about the streak centerline in the streamwise component, and the symmetry condition reverses in the spanwise component. It is further shown that sinuous mode dominates the turbulent kinematic energy(TKE) through the whole streak evolution process, the TKE content first increases along the streamwise direction to a saturation value and then decays slowly. In contrast, varicose mode exhibits a sustained growth of the TKE content,suggesting an increasing competition of varicose instability against sinuous instability.

Detection,Occurrence,and Survey of Rice Stripe and BlackStreaked Dwarf Diseases in Zhejiang Province,China

The major viral diseases that occur on rice plants in Zhejiang Province, eastern China, are stripe and rice black-streaked dwarf diseases. Rice stripe disease is only caused by rice stripe tenuivirus （RSV）, while rice black-streaked dwarf disease can be caused by rice black-streaked dwarf fijivirus （RBSDV） and/or southem rice black-streaked dwarf fijivirus （SRBSDV）. Here we review the characterization of these viruses, methods for their detection, and extensive surveys showing their occurrence and spread in the province.

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.

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.

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.

The Efficiency of Southern rice black-streaked dwarf virus Transmission by the Vector Sogatella furcifera to Different Host Plant Species

Southern rice black-streaked dwarf disease is a new rice disease that severely affects rice production in South China.To understand transmission capacity of the vector Sogatella furcifera to Southern rice black-streaked dwarf virus（SRBSDV） among different host plant species,potential host plants of SRBSDV collected from the diseased rice field and/or adjacent to the field in Hunan Province,China,were determined by RT-PCR,and the transmission rates of SRBSDV by S.furcifera among different host plant species were investigated.The results showed that host plants of SRBSDV in the rice fields were five of family Gramineae（Oryza sativa,Echinochloa crusgalli,Zea mays,Paspalum distichum,Alopecurus aequali） and two of family Cyperaceae（Juncellus serotinus and Cyperus difformis）.S.furcifera could not transmit SRBSDV between gramineous plants and cyperaceous plants,and could not transmit SRBSDV between the gramineous plants,J.serotinus and C.difformis as well.However,SRBSDV could be transmitted by S.furcifera within gramineous plants.S.furcifera could transmit SRBSDV between interspecies among three species plants（O.sativa,E.crusgalli and Z.mays）,and between P.distichum and A.aequali.At 15,20,25,30,and 35°C,both macropterous and brachypterous adult of S.furcifera could transmit SRBSDV from the plants（e.g.,E.crusgalli,Z.mays and O.sativa） infected with SRBSDV to rice seedlings.The transmission rates were first increased and then decreased with the increase of temperature.Macropterous adults transmitted SRBSDV from the viruliferous E.crusgalli,Z.may and rice plants to the healthy rice seedlings,and the infected rates of rice seedlings were 26.2,18.8 and 23.7% at 15°C,56.6,64.6 and 53.6% at 25°C,and was 11.2,10.2 and 7.3% at 35°C,respectively.Transmission capacity of brachypterous adults was significantly higher than that of macropterous adults at 15,20 and 25°C（P0.05）,while transmission capacity of brachypterous adults was relatively lower compared with that of macropterous ones at 35°C.These results offer evidence on the transmission of SRBSDV via the vector S.furcifer among different host plants,which can be helpful to control Southern rice black-streaked dwarf disease by the appropriate cultural measures in South China.

Genetic Analysis of Streaked and Abnormal Floret Mutant st-fon

A double mutant with streaked leaf and abnormal floret was found and temporarily named streaked leaf and floral organ number mutant （st-fon）. For this mutant, besides white streak appeared on culm, leaves and panicles, the number of floral organs increased and florets cracked. The extreme phenotype was that several small florets grew from one floret or branch rachis in small florets extended and developed into panicles. By using transmission electron microscope to observe the ultrastructure of white histocytes of leaves at the seedling stage, the white tissues which showed abnormal plastids, lamellas and thylakoids could not develop into normal chloroplast, and the development of chloroplast was blocked at the early growth stage of plastid. Scanning electron microscope and paraffin section were also used to observe the development of floral organs, and the results indicated that the development of floral meristem was out of order and unlimited, whereas in the twisty leaves, vascular bundle sheath cells grew excessively, or some bubbly cells increased. Genetic analyses carried out by means of cross and backcross with four normal-leaf-color materials revealed that the mutant is of cytoplasm inheritance.

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.

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.

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.

Design of a control system with high stability for a streak camera using isolated ADC

The streak camera is an ultra-fast diagnostic instrument with high sensitivity, and a high temporal and spatial resolution. It is primarily employed in various scientific research, such as inertial confinement fusion(ICF),synchrotron light sources, and electron–positron colliders.An automatic control system for an X-ray streak camera is presented in this paper. The output terminal of an analogto-digital converter was isolated from its input terminal, to reduce interference from high-voltage electrodes. Compared with traditional methods, this scheme also improved the internal electromagnetic interface immunity. Therefore,the system stability was enhanced. With this optimized control system, some characterizations of the streak camera were measured. Static and dynamic spatial resolutions of 25 and 20 lp/mm(CTF = 20%), respectively, were obtained. In addition, a dynamic range of 552:1 and a temporal resolution of 7.3 ps were achieved. The results confirmed that these characterizations are sufficient for the specifications derived from the diagnostic requirements of ICF.

Remote Monitoring of Wheat Streak Mosaic Progression Using Sub-Pixel Classification of Landsat 5 TM Imagery for Site Specific Disease Management in Winter Wheat

Wheat streak mosaic (WSM), caused by Wheat streak mosaic virus is a viral disease that affects wheat (Triticum aestivum L.), other grains, and numerous grasses over large geographical areas around the world. To improve disease management and crop production, it is essential to have adequate methods for monitoring disease epidemics at various scales and multiple times. Remote sensing has become an essential tool for monitoring and quantifying crop stress due to biotic and abiotic factors. The objective of our study was to explore the utility of Landsat 5 TM imagery for detecting, quantifying, and mapping the occurrence of WSM in irrigated commercial wheat fields. The infection and progression of WSM was biweekly assessed in the Texas Panhandle during the 2007-2008 crop years. Diseased-wheat was separated from uninfected wheat on the images using a sub-pixel classifier. The overall classification accuracies were >91% with kappa coefficient between 0.80 and 0.94 for disease detection were achieved. Omission errors varied between 2% and 14%, while commission errors ranged from 1% to 21%. These results indicate that the TM image can be used to accurately detect and quantify disease for site-specific WSM management. Remote detection of WSM using geospatial imagery may substantially improve monitoring, planning, and management practices by overcoming some of the shortcomings of the ground-based surveys such as observer bias and inaccessibility. Remote sensing techniques for accurate disease mapping offer a unique set of advantages including repeatability, large area coverage, and cost-effectiveness over the ground-based methods. Hence, remote detection is particularly and practically critical for repeated disease mo- nitoring and mapping over time and space during the course of a growing season.

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.

Transmission of Rice Black-Streaked Dwarf Virus from Frozen Infected Leaves to Healthy Rice Plants by Small Brown Planthopper (Laodelphax striatellus)

In order to preserve virus for identifying the resistance of rice varieties against rice black-streaked dwarf disease, a simple and reliable method was developed, through which virus-free small brown planthopper （SBPH） acquired rice black-streaked dwarf virus （RBSDV） from frozen infected leaves and the virus was transmitted to healthy rice plants. The experimental results showed that SBPH could obtain RBSDV from frozen infected rice leaves and the virus could be transmitted to a susceptible rice variety. For the ability to acquire RBSDV and transmit the virus to healthy plants by SBPH, there was no significant difference between frozen infected leaves and in vitro infected leaves. The novel method could be applied to identification of rice variety resistance to rice black-streaked dwarf disease, facilitating the breeding process for rice black-streaked dwarf disease resistance.

Color and chemical characterization of partially black-streaked heartwood in teak (Tectona grandis)

The heartwood of teak in certain areas of Java Island displays irregular black streaks along the annual rings. We investigated the color and chemical characteristics in a radial direction of partially black-streaked heartwood samples. Color properties （pH value, inorganic element, extractive content and extractive characterization） were measured in the color co-ordinates CIELAB system. The results show that the black streak part was 12-15 brightness （L^＊） value units less than the normal heartwood. Furthermore, the black streak part had more red （a^＊） but less yellow （b^＊）, hue （h） and chroma （C^＊） than the normal wood. The pH value, ash content and calcium contents of the black streak part were slightly higher than those obtained for the normal wood. The content of the low-polar extractive （n-hexane and ethyl acetate） of the black streak part was considerably higher than that for the normal wood. The blackening process was speculated to be a kind of defense mechanism indicated by remarkable amount ofbioactive compound called tectoquinone.

Screening of Broad-spectrum Resistance Resources against Rice Bacterial Leaf Streak

[ Objectives] Rice materials with broad-spectrum resistance against several pathogenic strains of Xanthomans oryzae pv. Oryzicola （Xooc） at multiple growth stages were screened, in order to provide reliable resistance sources for variety breeding against rice bacterial leaf streak. [ Methods] A total of 1 100 rice lines with rich genetic background were offered as selective objects, and highly susceptible cultivar Jingang 30 was used as the control. Inoculation was carried out with five strong pathogenic strains of Xooc through acupuncture method at various growth stages for resistance identification. [ Results] Fourteen disease-resistant materials were obtained through preliminary screening, accounting for 1.27% of the total materials. Nine materials moderately resistant to bacterial leaf streak were obtained via secondary screening, accounting for 0.82% of the total materials. Besides, three of them （ RL6, RL9 and RLL4） were resistant to a number of pathogenic strains of Xooc at three growth stages. In particular, RL16 presented broad-spectrum resistance to multi-strains with high resistance levels. Six of them （ RI2, RIA, RIS, RL8, RL11 and RL12） were resistant to single strain at single growth stage. [ Conclusions] The obtained three materials have broad-spectrum resistance to bacterial leaf streak at multiple growth stages, which can be served as an important source to cultivate disease-resistant rice varieties. RL6 maintains high broad-spectrum resistance at all growth stages, which can be used as a prior resistance source for rice variety breeding. Six materials obtained with resistance against bacterial leaf streak at particular growth stages can be used as candidate resistance sources.