The present work focuses on the development of a novel computer-based approach for tear ferning(TF)featuring.The original TF images of the recently developedfive-point grading scale have been used to assign a grade fo...The present work focuses on the development of a novel computer-based approach for tear ferning(TF)featuring.The original TF images of the recently developedfive-point grading scale have been used to assign a grade for any TF image automatically.A vector characteristic(VC)representing each grade was built using the reference images.A weighted combination between features selected from textures analysis using gray level co-occurrence matrix(GLCM),power spectrum(PS)analysis and linear specificity of the image were used to build the VC of each grade.A total of 14 features from texture analysis were used.PS at di®erent frequency points and number of line segments in each image were also used.Five features from GLCM have shown significant di®erences between the recently developed grading scale images which are:angular second moment at 0and 45,contrast,and correlation at 0and 45;thesefive features were all included in the characteristic vector.Three specific power frequencies were used in the VC because of the discrimination power.Number of line segments was also chosen because of dissimilarities between images.A VC for each grade of TF reference images was constructed and was found to be significantly different from each other's.This is a basic and fundamental step toward an automatic grading for computer-based diagnosis for dry eye.展开更多
Objective To evaluate the saliva ferning test (SFT) as diagnostic test for xerostomia in patients with Sjogren’s Syndrome (SS). Methods In this study, dried samples of freshly produced saliva from 78 patients with es...Objective To evaluate the saliva ferning test (SFT) as diagnostic test for xerostomia in patients with Sjogren’s Syndrome (SS). Methods In this study, dried samples of freshly produced saliva from 78 patients with established SS according to European Community criteria and 80 healthy controls were examined by light microscopy. The crystallization was classified into 4 types according to the ferning phenomenon: uniformity, branching, spreading and integrity (type I normal and type Ⅱ,Ⅲ,Ⅳ abnormal ). Then, the 78 patients underwent lebial salivary gland biopsy. According to Tarpley’s classifica- tion, minor salivary gland biopsy (≥2 + ) was considered to be positive . Results 1. The sensitivity of SFT was high (70/ 78 = 89. 74% ). And the specificity wes also high (67/80 = 83. 75% ). 2. Abnormal SFT was observed in 70/78 (89. 74% ) samples from patients group and in 13 /80 (16. 25% ) samples from healthy controls. The differences of SFT in patients group versus controls were statistically significant (P< 0. 01 ). 3. The sensitivity of SFT and mini labial gland biopsy had no significant differences (P > 0. 05) as diagnostic tests in SS. Conclusion SFT was simple, sensitive and specific as diagnostic test in SS suspect patients just as mini labial gland biopsy.展开更多
[Objectives]To analyze the composition of lycophytes and ferns in Yunzhongshan Nature Reserve,Fujian Province.[Methods]This study examined the composition of lycophytes and ferns in Yunzhongshan Nature Reserve through...[Objectives]To analyze the composition of lycophytes and ferns in Yunzhongshan Nature Reserve,Fujian Province.[Methods]This study examined the composition of lycophytes and ferns in Yunzhongshan Nature Reserve through field investigations and specimen identification,supplemented by a review of relevant literature.[Results]A total of 84 species of lycophytes and ferns were identified,encompassing 55 genera and 29 families.This included 14 species of lycophytes distributed across 8 genera and 3 families,as well as 70 species of ferns belonging to 47 genera and 26 families.Polypodiaceae and Selaginella were the dominant family and genus,respectively,while oligospecific families and monotypic genera were significant components of lycophytes and ferns in the region.The distribution types of these families were primarily cosmopolitan and tropical.The Germline differentiation degree(SD)was 3.34,and the proportion of rare or endangered species among lycophytes and ferns was 8.33%.[Conclusions]Yunzhongshan Nature Reserve possesses a diverse array of lycophyte and fern species.This study offers valuable scientific insights that can inform efforts related to the conservation of biodiversity,resource utilization and development,species introduction,and system evolution of lycophytes and ferns within the reserve.展开更多
Background Transgenic research in crops involves using genetic engineering techniques to introduce specific genes of interest from other organisms,or even entirely new genes into plant genomes to create crops with des...Background Transgenic research in crops involves using genetic engineering techniques to introduce specific genes of interest from other organisms,or even entirely new genes into plant genomes to create crops with desirable traits that wouldn’t be possible through conventional breeding methods.Transgenic crops have been developed for various traits globally.Whitefly,Bemisia tabaci(Gennadius)is one of the major sucking pests of cotton that cause significant damage to the cotton production.To combat whitefly infestations,researchers have developed four transgenic cotton lines expressing the fern protein.And those transgenic lines need to be evaluated for their performance against the target pest—whitefly.The evaluation was designed as controlled trials in polyhouse or muslin cloth cages under open-choice and no-choice conditions by comparing four transgenic cotton lines(A,B,C,and D)with three control groups,including untransformed cotton plants with a same genetic background of the transgenic line,conventionally bred whitefly-resistant cotton,and whitefly-susceptible cotton.In order to study the generational effect,the evaluation also involved studies on whitefly development in laboratory,muslin cloth cage,and polyhouse conditions.Results Both open-choice and no-choice experiments had shown that all the four transgenic cotton lines(A,B,C,and D)expressing the fern protein reduced adult whitefly numbers significantly compared with the control lines,except for the no-choice conditions in 2021,where the transgenic line C was non-significant different from the resistant control line.Notably,the nymphal population on the resistant control line was relatively low and nonsignificant different from the transgenic line C in 2021;and the transgenic lines A and C in 2022 under open-choice conditions.Under no-choice condition,the nymphal counts in the resistant control line was non-significant different from transgenic lines C and D in 2021;and transgenic line D in 2022.All transgenic lines showed significant decrease in egg hatching in 2021 and nymphal development in 2022,except for the transgenic line C which had no significant different in the nymphal development comparing with non-transgenic control lines in 2022.Adult emergence rates in both years of evaluation showed significant decrease in transgenic lines A and B comparing with the control lines.Additionally,the results showed a significant reduction in cotton leaf curl disease and sooty mold development in all the four transgenic lines compared with susceptible control under open-choice conditions,indicating potential benefits of transgenic lines beyond direct effect on whitefly control.Furthermore,the research explored the generational effects of the fern protein on whitefly which revealed the lowest fecundity in the transgenic line C across F0,F1 and F3 generations,lower egg hatching in F1 and F2 generations in transgenic lines A and B,shorter nymphal duration in F1 and F2 generations in transgenic line B,and the least total adult emergence in the transgenic line C in F0 and F3 generations.Conclusions These findings suggest that the transgenic cotton lines expressing fern protein disrupts whitefly populations and the life cycle to a certain extent.However,results are not consistent over generations and years of study,indicating these transgenic lines were not superior over control lines and need to be improved in future breeding.展开更多
The Chilean Pampean flat slab subduction segment is characterized by the nearly horizontal subduction of the Nazca Plate within the depth range of 100-120 km.Numerous seismic tomography studies have been conducted to ...The Chilean Pampean flat slab subduction segment is characterized by the nearly horizontal subduction of the Nazca Plate within the depth range of 100-120 km.Numerous seismic tomography studies have been conducted to investigate its velocity structure;however,they have used only seismic body wave data or surface wave data.As a result,the existing velocity models in the region may have relatively large uncertainties.In this study,we use body wave arrival times from earthquakes occurring in central Chile between 2014 and 2019,as well as Rayleigh wave phase velocity maps at periods of 5-80 s from ambient noise empirical Green’s functions in Chile.By jointly using body wave arrival times and surface wave dispersion data,we refine the VS model and improve earthquake locations in the central Chile subduction zone.Compared with previous velocity models,our velocity model better reveals an eastward-dipping high-velocity plate representing the subducting Nazca Plate,which is 40-50 km thick and is more consistent with the slab thickness estimated by receiver function imaging and thermal modeling.Overall,the intraslab seismicity distribution spatially correlates well with the slab high-velocity anomalies except along the subduction paths of the CopiapóRidge and Juan Fernández Ridge.Additionally,parallel low-velocity stripes are imaged beneath the subducting plate,which are likely associated with the accumulated melts.The joint inversion velocity model also resolves widespread low-velocity anomalies in the crust beneath the Central Volcanic Zone of the central Andes,likely representing crustal magma chambers for various volcanoes.展开更多
The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the dive...The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the diversity of very few groups of ferns in this region has been explored using combined molecular and morphological approaches.Here,we updated the plastid phylogeny of the Java fern genus Leptochilus with 226(115%increase of the latest sampling)samples across the distribution range,specifically those of three phylogenetically significant species,Leptochilus ovatus,L.pedunculatus,and L.pothifolius.We also reconstructed the first nuclear phylogeny of the genus based on pgiC gene data.Based on molecular and morphological evidence,we identified three new major clades and six new subclades,redefined three existing species,discovered a number of cryptic species of the genus,and elucidated the evolution of the three most variable characters.Our divergence time analyses and ancestral area reconstruction showed that Leptochilus originated in the Oligocene and diversified from early Miocene and 15 dispersal events from lower to higher latitudes are identified.The evolution of three most important morphological characters is analyzed in a context of the new phylogeny.Our analysis showed that 30(59%of total 51)species of Leptochilus occur in Indo-Burma hotspot,24(80%of the 30 species)of which are endemic to this hotspot.We argue that the Indo-Burma hotspot should be recognized as a diversity hotspot for ferns.展开更多
The ultrastructure of oogenesis in the fern Osmunda cinnamomea L. var. asiatica Fernald has been studied by electron microscopy. During oogenesis, numerous vesicles not only moved towards the periphery, but also were ...The ultrastructure of oogenesis in the fern Osmunda cinnamomea L. var. asiatica Fernald has been studied by electron microscopy. During oogenesis, numerous vesicles not only moved towards the periphery, but also were arranged in line along the inside of plasmalemma, and in addition aggregated outside the plasmalemma by exocytosis. They released or excreted osmiophilic material. It was observed that a few vesicles containing lamellar osmiophilic material situated closely along the plasmalemma, seemed to break open. Simultaneously, a separation cavity between egg cell and archegonium wall formed. Its width was broader than the other advanced ferns reported previously, and an extra egg membrane occurred outside around the plasmalemma of the egg, its thickness being greater than in Pteridium and Dryopteris. Amyloplasts around the nucleus were filled with large triangular semicircular or subelliptical starch grains, but as the egg matured they progressively decreased. Nucleus was large and flattened, and paired membrane in two to three couples laid within the nucleus, close and parallel to the nuclear membrane. No nuclear evagination was observed. Mitochondria seemed to have been undeveloped, but finally recovered normally.展开更多
Through investigating the wild ornamental ferns in Guizhou Province, it is found that there are totally 312 species (including variations), 111 genera and 49 families of such resources in this region, which are classi...Through investigating the wild ornamental ferns in Guizhou Province, it is found that there are totally 312 species (including variations), 111 genera and 49 families of such resources in this region, which are classified into terrestrial fern, epiphytic fern, saxicolous fern, vine fern, tree fern and aquatic fern according to their ecological types. The application of ornamental ferns in garden landscaping and development countermeasures are analyzed in this study.展开更多
64 species （including 5 varieties）, 30 genera and 24 families of the edible ferns in Guizhou are preliminartiy confirmed, according to the combination of spot investigation and refereuce analySis：the species, gener...64 species （including 5 varieties）, 30 genera and 24 families of the edible ferns in Guizhou are preliminartiy confirmed, according to the combination of spot investigation and refereuce analySis：the species, genera and families account for 8.13%, 19.74% and 44.44% of ferns in Guizhou, respectively. The floristic composition characters and resource distribution of 23 kinds of the edible ferns in Guizhou are described.展开更多
Tracking registration is a key issue in augmented reality applications,particularly where there are no artificial identifier placed manually.In this paper,an efficient markerless tracking registration algorithm which ...Tracking registration is a key issue in augmented reality applications,particularly where there are no artificial identifier placed manually.In this paper,an efficient markerless tracking registration algorithm which combines the detector and the tracker is presented for the augmented reality system.We capture the target images in real scenes as template images,use the random ferns classifier for target detection and solve the problem of reinitialization after tracking registration failures due to changes in ambient lighting or occlusion of targets.Once the target has been successfully detected,the pyramid Lucas-Kanade(LK)optical flow tracker is used to track the detected target in real time to solve the problem of slow speed.The least median of squares(LMedS)method is used to adaptively calculate the homography matrix,and then the three-dimensional pose is estimated and the virtual object is rendered and registered.Experimental results demonstrate that the algorithm is more accurate,faster and more robust.展开更多
Suitable habitat is vital for the survival and restoration of a species.Understanding the suitable habitat range for lycophytes and ferns is prerequisite for effective species resource conservation and recovery effort...Suitable habitat is vital for the survival and restoration of a species.Understanding the suitable habitat range for lycophytes and ferns is prerequisite for effective species resource conservation and recovery efforts.In this study, we took Athyrium brevifrons as an example, predicted its suitable habitat using a Maxent model with 67 occurrence data and nine environmental variables in Northeast China.The area under the curve(AUC) value of independent test data, as well as the comparison with specimen county areal distribution of A.brevifrons exhibited excellent predictive performance.The type of environmental variables showed that precipitation contributed the most to the distribution prediction, followed by temperature and topography.Percentage contribution and permutation importance both indicated that precipitation of driest quarter(Bio17) was the key factor in determining the natural distribution of A.brevifrons, the reason could be proved by the fern gametophyte biology.The analysis of high habitat suitability areas also showed the habitat preference of A.brevifrons: comparatively more precipitation and less fluctuation in the driest quarter.Changbai Mountains, covering almost all the high and medium habitat suitability areas, provide the best ecological conditions for the survival of A.brevifrons, and should be considered as priority areas for protection and restoration of the wild resource.The potential habitat suitability distribution map could provide a reference for the sustainable development and utilisation of A.brevifrons resource, and Maxent modelling could be valuable for conservation management planning for lycophytes and ferns in Northeast China.展开更多
文摘The present work focuses on the development of a novel computer-based approach for tear ferning(TF)featuring.The original TF images of the recently developedfive-point grading scale have been used to assign a grade for any TF image automatically.A vector characteristic(VC)representing each grade was built using the reference images.A weighted combination between features selected from textures analysis using gray level co-occurrence matrix(GLCM),power spectrum(PS)analysis and linear specificity of the image were used to build the VC of each grade.A total of 14 features from texture analysis were used.PS at di®erent frequency points and number of line segments in each image were also used.Five features from GLCM have shown significant di®erences between the recently developed grading scale images which are:angular second moment at 0and 45,contrast,and correlation at 0and 45;thesefive features were all included in the characteristic vector.Three specific power frequencies were used in the VC because of the discrimination power.Number of line segments was also chosen because of dissimilarities between images.A VC for each grade of TF reference images was constructed and was found to be significantly different from each other's.This is a basic and fundamental step toward an automatic grading for computer-based diagnosis for dry eye.
文摘Objective To evaluate the saliva ferning test (SFT) as diagnostic test for xerostomia in patients with Sjogren’s Syndrome (SS). Methods In this study, dried samples of freshly produced saliva from 78 patients with established SS according to European Community criteria and 80 healthy controls were examined by light microscopy. The crystallization was classified into 4 types according to the ferning phenomenon: uniformity, branching, spreading and integrity (type I normal and type Ⅱ,Ⅲ,Ⅳ abnormal ). Then, the 78 patients underwent lebial salivary gland biopsy. According to Tarpley’s classifica- tion, minor salivary gland biopsy (≥2 + ) was considered to be positive . Results 1. The sensitivity of SFT was high (70/ 78 = 89. 74% ). And the specificity wes also high (67/80 = 83. 75% ). 2. Abnormal SFT was observed in 70/78 (89. 74% ) samples from patients group and in 13 /80 (16. 25% ) samples from healthy controls. The differences of SFT in patients group versus controls were statistically significant (P< 0. 01 ). 3. The sensitivity of SFT and mini labial gland biopsy had no significant differences (P > 0. 05) as diagnostic tests in SS. Conclusion SFT was simple, sensitive and specific as diagnostic test in SS suspect patients just as mini labial gland biopsy.
基金Supported by National Key Protected Plant Investigation Project in Anxi Yunzhongshan Nature Reserve Primarily Focusing on Alsophila spinulosa,Paris polyphylla,and Angiopteris fokiensis([350524]BWZ[CS]2024003).
文摘[Objectives]To analyze the composition of lycophytes and ferns in Yunzhongshan Nature Reserve,Fujian Province.[Methods]This study examined the composition of lycophytes and ferns in Yunzhongshan Nature Reserve through field investigations and specimen identification,supplemented by a review of relevant literature.[Results]A total of 84 species of lycophytes and ferns were identified,encompassing 55 genera and 29 families.This included 14 species of lycophytes distributed across 8 genera and 3 families,as well as 70 species of ferns belonging to 47 genera and 26 families.Polypodiaceae and Selaginella were the dominant family and genus,respectively,while oligospecific families and monotypic genera were significant components of lycophytes and ferns in the region.The distribution types of these families were primarily cosmopolitan and tropical.The Germline differentiation degree(SD)was 3.34,and the proportion of rare or endangered species among lycophytes and ferns was 8.33%.[Conclusions]Yunzhongshan Nature Reserve possesses a diverse array of lycophyte and fern species.This study offers valuable scientific insights that can inform efforts related to the conservation of biodiversity,resource utilization and development,species introduction,and system evolution of lycophytes and ferns within the reserve.
文摘Background Transgenic research in crops involves using genetic engineering techniques to introduce specific genes of interest from other organisms,or even entirely new genes into plant genomes to create crops with desirable traits that wouldn’t be possible through conventional breeding methods.Transgenic crops have been developed for various traits globally.Whitefly,Bemisia tabaci(Gennadius)is one of the major sucking pests of cotton that cause significant damage to the cotton production.To combat whitefly infestations,researchers have developed four transgenic cotton lines expressing the fern protein.And those transgenic lines need to be evaluated for their performance against the target pest—whitefly.The evaluation was designed as controlled trials in polyhouse or muslin cloth cages under open-choice and no-choice conditions by comparing four transgenic cotton lines(A,B,C,and D)with three control groups,including untransformed cotton plants with a same genetic background of the transgenic line,conventionally bred whitefly-resistant cotton,and whitefly-susceptible cotton.In order to study the generational effect,the evaluation also involved studies on whitefly development in laboratory,muslin cloth cage,and polyhouse conditions.Results Both open-choice and no-choice experiments had shown that all the four transgenic cotton lines(A,B,C,and D)expressing the fern protein reduced adult whitefly numbers significantly compared with the control lines,except for the no-choice conditions in 2021,where the transgenic line C was non-significant different from the resistant control line.Notably,the nymphal population on the resistant control line was relatively low and nonsignificant different from the transgenic line C in 2021;and the transgenic lines A and C in 2022 under open-choice conditions.Under no-choice condition,the nymphal counts in the resistant control line was non-significant different from transgenic lines C and D in 2021;and transgenic line D in 2022.All transgenic lines showed significant decrease in egg hatching in 2021 and nymphal development in 2022,except for the transgenic line C which had no significant different in the nymphal development comparing with non-transgenic control lines in 2022.Adult emergence rates in both years of evaluation showed significant decrease in transgenic lines A and B comparing with the control lines.Additionally,the results showed a significant reduction in cotton leaf curl disease and sooty mold development in all the four transgenic lines compared with susceptible control under open-choice conditions,indicating potential benefits of transgenic lines beyond direct effect on whitefly control.Furthermore,the research explored the generational effects of the fern protein on whitefly which revealed the lowest fecundity in the transgenic line C across F0,F1 and F3 generations,lower egg hatching in F1 and F2 generations in transgenic lines A and B,shorter nymphal duration in F1 and F2 generations in transgenic line B,and the least total adult emergence in the transgenic line C in F0 and F3 generations.Conclusions These findings suggest that the transgenic cotton lines expressing fern protein disrupts whitefly populations and the life cycle to a certain extent.However,results are not consistent over generations and years of study,indicating these transgenic lines were not superior over control lines and need to be improved in future breeding.
基金funded by the National Natural Science Foundation of China under Grant 42230101the National Agency for Research and Development of Chile(ANID)by Projects AFB180004 and AFB220002the ANID Programa de Cooperación Internacional(PCI)Grant PII-180003.
文摘The Chilean Pampean flat slab subduction segment is characterized by the nearly horizontal subduction of the Nazca Plate within the depth range of 100-120 km.Numerous seismic tomography studies have been conducted to investigate its velocity structure;however,they have used only seismic body wave data or surface wave data.As a result,the existing velocity models in the region may have relatively large uncertainties.In this study,we use body wave arrival times from earthquakes occurring in central Chile between 2014 and 2019,as well as Rayleigh wave phase velocity maps at periods of 5-80 s from ambient noise empirical Green’s functions in Chile.By jointly using body wave arrival times and surface wave dispersion data,we refine the VS model and improve earthquake locations in the central Chile subduction zone.Compared with previous velocity models,our velocity model better reveals an eastward-dipping high-velocity plate representing the subducting Nazca Plate,which is 40-50 km thick and is more consistent with the slab thickness estimated by receiver function imaging and thermal modeling.Overall,the intraslab seismicity distribution spatially correlates well with the slab high-velocity anomalies except along the subduction paths of the CopiapóRidge and Juan Fernández Ridge.Additionally,parallel low-velocity stripes are imaged beneath the subducting plate,which are likely associated with the accumulated melts.The joint inversion velocity model also resolves widespread low-velocity anomalies in the crust beneath the Central Volcanic Zone of the central Andes,likely representing crustal magma chambers for various volcanoes.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0502)a grant from Yunnan Fundamental Research Projects(Grant#202201BC070001)a Yunnan Revitalization Talent Support Program“Young Talent”Project and a CAS Scholarship to Liang Zhang.
文摘The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the diversity of very few groups of ferns in this region has been explored using combined molecular and morphological approaches.Here,we updated the plastid phylogeny of the Java fern genus Leptochilus with 226(115%increase of the latest sampling)samples across the distribution range,specifically those of three phylogenetically significant species,Leptochilus ovatus,L.pedunculatus,and L.pothifolius.We also reconstructed the first nuclear phylogeny of the genus based on pgiC gene data.Based on molecular and morphological evidence,we identified three new major clades and six new subclades,redefined three existing species,discovered a number of cryptic species of the genus,and elucidated the evolution of the three most variable characters.Our divergence time analyses and ancestral area reconstruction showed that Leptochilus originated in the Oligocene and diversified from early Miocene and 15 dispersal events from lower to higher latitudes are identified.The evolution of three most important morphological characters is analyzed in a context of the new phylogeny.Our analysis showed that 30(59%of total 51)species of Leptochilus occur in Indo-Burma hotspot,24(80%of the 30 species)of which are endemic to this hotspot.We argue that the Indo-Burma hotspot should be recognized as a diversity hotspot for ferns.
文摘The ultrastructure of oogenesis in the fern Osmunda cinnamomea L. var. asiatica Fernald has been studied by electron microscopy. During oogenesis, numerous vesicles not only moved towards the periphery, but also were arranged in line along the inside of plasmalemma, and in addition aggregated outside the plasmalemma by exocytosis. They released or excreted osmiophilic material. It was observed that a few vesicles containing lamellar osmiophilic material situated closely along the plasmalemma, seemed to break open. Simultaneously, a separation cavity between egg cell and archegonium wall formed. Its width was broader than the other advanced ferns reported previously, and an extra egg membrane occurred outside around the plasmalemma of the egg, its thickness being greater than in Pteridium and Dryopteris. Amyloplasts around the nucleus were filled with large triangular semicircular or subelliptical starch grains, but as the egg matured they progressively decreased. Nucleus was large and flattened, and paired membrane in two to three couples laid within the nucleus, close and parallel to the nuclear membrane. No nuclear evagination was observed. Mitochondria seemed to have been undeveloped, but finally recovered normally.
文摘Through investigating the wild ornamental ferns in Guizhou Province, it is found that there are totally 312 species (including variations), 111 genera and 49 families of such resources in this region, which are classified into terrestrial fern, epiphytic fern, saxicolous fern, vine fern, tree fern and aquatic fern according to their ecological types. The application of ornamental ferns in garden landscaping and development countermeasures are analyzed in this study.
基金Supported by Guiyang Science and Technology Planning Project~~
文摘64 species （including 5 varieties）, 30 genera and 24 families of the edible ferns in Guizhou are preliminartiy confirmed, according to the combination of spot investigation and refereuce analySis：the species, genera and families account for 8.13%, 19.74% and 44.44% of ferns in Guizhou, respectively. The floristic composition characters and resource distribution of 23 kinds of the edible ferns in Guizhou are described.
基金supported by National Natural Science Foundation of China(No.61125101).
文摘Tracking registration is a key issue in augmented reality applications,particularly where there are no artificial identifier placed manually.In this paper,an efficient markerless tracking registration algorithm which combines the detector and the tracker is presented for the augmented reality system.We capture the target images in real scenes as template images,use the random ferns classifier for target detection and solve the problem of reinitialization after tracking registration failures due to changes in ambient lighting or occlusion of targets.Once the target has been successfully detected,the pyramid Lucas-Kanade(LK)optical flow tracker is used to track the detected target in real time to solve the problem of slow speed.The least median of squares(LMedS)method is used to adaptively calculate the homography matrix,and then the three-dimensional pose is estimated and the virtual object is rendered and registered.Experimental results demonstrate that the algorithm is more accurate,faster and more robust.
基金Under the auspices of National Key Research and Development Program of China(No.2016YFC0500300)National Natural Science Foundation of China(No.41675153)
文摘Suitable habitat is vital for the survival and restoration of a species.Understanding the suitable habitat range for lycophytes and ferns is prerequisite for effective species resource conservation and recovery efforts.In this study, we took Athyrium brevifrons as an example, predicted its suitable habitat using a Maxent model with 67 occurrence data and nine environmental variables in Northeast China.The area under the curve(AUC) value of independent test data, as well as the comparison with specimen county areal distribution of A.brevifrons exhibited excellent predictive performance.The type of environmental variables showed that precipitation contributed the most to the distribution prediction, followed by temperature and topography.Percentage contribution and permutation importance both indicated that precipitation of driest quarter(Bio17) was the key factor in determining the natural distribution of A.brevifrons, the reason could be proved by the fern gametophyte biology.The analysis of high habitat suitability areas also showed the habitat preference of A.brevifrons: comparatively more precipitation and less fluctuation in the driest quarter.Changbai Mountains, covering almost all the high and medium habitat suitability areas, provide the best ecological conditions for the survival of A.brevifrons, and should be considered as priority areas for protection and restoration of the wild resource.The potential habitat suitability distribution map could provide a reference for the sustainable development and utilisation of A.brevifrons resource, and Maxent modelling could be valuable for conservation management planning for lycophytes and ferns in Northeast China.
