In five-axis machining,tool orientation above a blade stream surface may lead to tool collision and a decrease in workpiece rigidity.Hence,collisionless tool orientation smoothing(TOS)becomes an important issue.On the...In five-axis machining,tool orientation above a blade stream surface may lead to tool collision and a decrease in workpiece rigidity.Hence,collisionless tool orientation smoothing(TOS)becomes an important issue.On the basis of a constant scallop height tool path,the triangular facets in the faces,vertices format are constructed from cutter contact(CC)using the Voronoi incremental algorithm.The cutter location(CL)points candidate set is represented by an oblique elliptic cone whose vertex lies at CC using NURBS envelope.Whether the CL point is above its CC is judged by the dot product between the normal vector and the point on triangulation nearest to the CL point.The curvatures at CC are obtained by fitting a moving least square(MLS) quadratic patch to the local neighborhood of a vertex and calculating eigenvectors and eigenvalues of the Hessian matrix.Triangular surface elastic energy is employed as the weight in selection from the NURBS envelope.The collision is judged by NURBS surface intersection.TOS can then be expressed by selecting a CL point for each CC point and converted into a numerical control(NC)code automatically according to the postprocessor type of the machine center.The proposed method is verified by finishing of a cryogenic turboexpander impeller of air separation equipment.展开更多
Background:Timing of breeding season of temperate passerines has been considered to be adjusted to their food availability.There is little work to reveal the cell stress responses of the nestlings hatched asynchronize...Background:Timing of breeding season of temperate passerines has been considered to be adjusted to their food availability.There is little work to reveal the cell stress responses of the nestlings hatched asynchronized with the food abundance peak,which is important for understanding the physiological link between the timing of breeding and the fitness of offspring.Methods:Using gene expression level of blood HSP70 and HSP90 as indicators,we compared the cell stress response of Asian Short-toed Lark(Calandrella cheleensis)nestlings hatched under conditions of low,mid or high food(grasshopper nymph)availability in 2017.Results:Nymph biomass,sample time and interaction of these two factors significantly influenced the blood gene expression level of HSP70 and HSP90 of Asian Short-toed Lark nestlings.HSP70 and HSP90 gene expression levels of the nestlings at 14:00 were significantly higher than those at 5:00.At either 5:00 or 14:00,the gene expression levels of HSP70 and HSP90 increase with the decrease of nymph biomass.Conclusions:These results indicate that food availability is an important environment factor inducing cellular stress of Asian Short-toed Lark nestlings.The interactive effect of the nymph abundance and sample time on the HSPs response may be related with the daily temperature variation of the grassland.Over cell stress response may be one of physiological factor mediating the effect of food availability and the nestling’s fitness.展开更多
Abstract Instagram is a popular photo-sharing social ap- plication. It is widely used by tourists to record their journey information such as location, time and interest. Consequently, a huge volume of get-tagged phot...Abstract Instagram is a popular photo-sharing social ap- plication. It is widely used by tourists to record their journey information such as location, time and interest. Consequently, a huge volume of get-tagged photos with spatio-temporal in- formation are generated along tourist＇s travel trajectories. Such Instagram photo trajectories consist of travel paths, travel density distributions, and traveller behaviors, prefer- ences, and mobility patterns. Mining Instagram photo trajec- tories is thus very useful for many mobile and location-based social applications, including tour guide and recommender systems. However, we have not found any work that extracts interesting group-like travel trajectories from Instagram pho- tos asynchronously taken by different tourists. Motivated by this, we propose a novel concept： coterie, which reveals representative travel trajectory patterns hidden in Instagram photos taken by users at shared locations and paths. Our work includes the discovery of （1） coteries, （2） closed co- teries, and （3） the recommendation of popular travel routes based on closed coteries. For this, we first build a statistically reliable trajectory database from Instagram get-tagged pho- tos. These trajectories are then clustered by the DBSCAN method to find tourist density. Next, we transform each raw spatio-temporal trajectory into a sequence of clusters. All dis- criminative closed coteries are further identified by a Cluster- Growth algorithm. Finally, distance-aware and conformity- aware recommendation strategies are applied on closed co- teries to recommend popular tour routes. Visualized demosand extensive experimental results demonstrate the effective- ness and efficiency of our methods.展开更多
Purpose: Historically the classification of Thoracic Outlet Syndrome (TOS) has been based on symptoms rather than the underlying pathology. Therefore, TOS has been classified into Neurogenic (NTOS), Venous (VTOS or Pa...Purpose: Historically the classification of Thoracic Outlet Syndrome (TOS) has been based on symptoms rather than the underlying pathology. Therefore, TOS has been classified into Neurogenic (NTOS), Venous (VTOS or Paget Schroetter Syndrome) and Arterial (ATOS) subgroups. This classification has resulted in confusion among medical practitioners, difficulty in making the diagnosis, and the poor results with surgical intervention. Methods: The published papers from PubMed on the newer understanding of the pathogenesis and the surgical treatment of TOS were reviewed. Results: More recently TOS has been classified based on the underlying pathologic entity. Based on this classification, patients who are suspected of having TOS should be classified as having 1. Cervical Rib Disease (CRD), or 2. TOS as the result of “Subclavian Vein Compression Syndrome”. This classification has resulted in more accurate diagnosis, better patient selection for surgery, and excellent surgical results. This paper outlines the algorithm for making the appropriate diagnosis in patients who present with neurovascular symptoms of the upper extremity and the selection of the appropriate patients for surgery. Conclusion: Based on the algorithm for surgical decision making, patients with Cervical Rib Disease should undergo cervical exploration and resection of the pathologic entity which results in compression of the brachial plexus or the subclavian artery in the neck. Patients with Thoracic outlet Syndrome who are found to have extrinsic compression of the subclavian vein by a pathologic tubercle at the sternocostal joint on Multiphasic MRA should undergo robotic first rib resection.展开更多
基金Project supported by the National Basic Research Program (973) of China (No. 2011CB706506)the National Science and Technology Major Project of China (Nos. 2011ZX04014-131 and 2012ZX04010 011)the National Science Foundation for Young Scholars of China (No. 51005204)
文摘In five-axis machining,tool orientation above a blade stream surface may lead to tool collision and a decrease in workpiece rigidity.Hence,collisionless tool orientation smoothing(TOS)becomes an important issue.On the basis of a constant scallop height tool path,the triangular facets in the faces,vertices format are constructed from cutter contact(CC)using the Voronoi incremental algorithm.The cutter location(CL)points candidate set is represented by an oblique elliptic cone whose vertex lies at CC using NURBS envelope.Whether the CL point is above its CC is judged by the dot product between the normal vector and the point on triangulation nearest to the CL point.The curvatures at CC are obtained by fitting a moving least square(MLS) quadratic patch to the local neighborhood of a vertex and calculating eigenvectors and eigenvalues of the Hessian matrix.Triangular surface elastic energy is employed as the weight in selection from the NURBS envelope.The collision is judged by NURBS surface intersection.TOS can then be expressed by selecting a CL point for each CC point and converted into a numerical control(NC)code automatically according to the postprocessor type of the machine center.The proposed method is verified by finishing of a cryogenic turboexpander impeller of air separation equipment.
基金supported by the National Natural Science Foundation of China(No.31872246)
文摘Background:Timing of breeding season of temperate passerines has been considered to be adjusted to their food availability.There is little work to reveal the cell stress responses of the nestlings hatched asynchronized with the food abundance peak,which is important for understanding the physiological link between the timing of breeding and the fitness of offspring.Methods:Using gene expression level of blood HSP70 and HSP90 as indicators,we compared the cell stress response of Asian Short-toed Lark(Calandrella cheleensis)nestlings hatched under conditions of low,mid or high food(grasshopper nymph)availability in 2017.Results:Nymph biomass,sample time and interaction of these two factors significantly influenced the blood gene expression level of HSP70 and HSP90 of Asian Short-toed Lark nestlings.HSP70 and HSP90 gene expression levels of the nestlings at 14:00 were significantly higher than those at 5:00.At either 5:00 or 14:00,the gene expression levels of HSP70 and HSP90 increase with the decrease of nymph biomass.Conclusions:These results indicate that food availability is an important environment factor inducing cellular stress of Asian Short-toed Lark nestlings.The interactive effect of the nymph abundance and sample time on the HSPs response may be related with the daily temperature variation of the grassland.Over cell stress response may be one of physiological factor mediating the effect of food availability and the nestling’s fitness.
文摘Abstract Instagram is a popular photo-sharing social ap- plication. It is widely used by tourists to record their journey information such as location, time and interest. Consequently, a huge volume of get-tagged photos with spatio-temporal in- formation are generated along tourist＇s travel trajectories. Such Instagram photo trajectories consist of travel paths, travel density distributions, and traveller behaviors, prefer- ences, and mobility patterns. Mining Instagram photo trajec- tories is thus very useful for many mobile and location-based social applications, including tour guide and recommender systems. However, we have not found any work that extracts interesting group-like travel trajectories from Instagram pho- tos asynchronously taken by different tourists. Motivated by this, we propose a novel concept： coterie, which reveals representative travel trajectory patterns hidden in Instagram photos taken by users at shared locations and paths. Our work includes the discovery of （1） coteries, （2） closed co- teries, and （3） the recommendation of popular travel routes based on closed coteries. For this, we first build a statistically reliable trajectory database from Instagram get-tagged pho- tos. These trajectories are then clustered by the DBSCAN method to find tourist density. Next, we transform each raw spatio-temporal trajectory into a sequence of clusters. All dis- criminative closed coteries are further identified by a Cluster- Growth algorithm. Finally, distance-aware and conformity- aware recommendation strategies are applied on closed co- teries to recommend popular tour routes. Visualized demosand extensive experimental results demonstrate the effective- ness and efficiency of our methods.
文摘Purpose: Historically the classification of Thoracic Outlet Syndrome (TOS) has been based on symptoms rather than the underlying pathology. Therefore, TOS has been classified into Neurogenic (NTOS), Venous (VTOS or Paget Schroetter Syndrome) and Arterial (ATOS) subgroups. This classification has resulted in confusion among medical practitioners, difficulty in making the diagnosis, and the poor results with surgical intervention. Methods: The published papers from PubMed on the newer understanding of the pathogenesis and the surgical treatment of TOS were reviewed. Results: More recently TOS has been classified based on the underlying pathologic entity. Based on this classification, patients who are suspected of having TOS should be classified as having 1. Cervical Rib Disease (CRD), or 2. TOS as the result of “Subclavian Vein Compression Syndrome”. This classification has resulted in more accurate diagnosis, better patient selection for surgery, and excellent surgical results. This paper outlines the algorithm for making the appropriate diagnosis in patients who present with neurovascular symptoms of the upper extremity and the selection of the appropriate patients for surgery. Conclusion: Based on the algorithm for surgical decision making, patients with Cervical Rib Disease should undergo cervical exploration and resection of the pathologic entity which results in compression of the brachial plexus or the subclavian artery in the neck. Patients with Thoracic outlet Syndrome who are found to have extrinsic compression of the subclavian vein by a pathologic tubercle at the sternocostal joint on Multiphasic MRA should undergo robotic first rib resection.
