The Generic Annular Bucket Histogram for Estimating the Selectivity of Spatial Selection and Spatial Join

Selectivity estimation is crucial for query optimizers choosing an optimal spatial execution plan in a spatial database management system.This paper presents an Annular Bucket spatial histogram(AB histogram)that can estimate the selectivity in finer spatial selection and spatial join operations even when the spatial query has more operators or more joins.The AB histogram is represented as a set of bucket-range,bucket-count value pairs.The bucket-range often covers an annular region like a sin-gle-cell-sized photo frame.The bucket-count is the number of objects whose Minimum Bounding Rectangles(MBRs)fall between outer rectangle and inner rectangle of the bucket-range.Assuming that all MBRs in each a bucket distribute evenly,for every buck-et,we can obtain serial probabilities that satisfy a certain spatial selection or join conditions from the operations' semantics and the spatial relations between every bucket-range and query ranges.Thus,according to some probability theories,spatial selection or join selectivity can be estimated by the every bucket-count and its probabilities.This paper also shows a way to generate an updated AB histogram from an original AB histogram and those probabilities.Our tests show that the AB histogram not only supports the selectivity estimation of spatial selection or spatial join with "disjoint","intersect","within","contains",and "overlap" operators but also provides an approach to generate a reliable updated histogram whose spatial distribution is close to the distribution of ac-tual query result.

Gene-associated microsatellite markers confi rm panmixia and indicate a diff erent pattern of spatially varying selection in the endangered Japanese eel Anguilla japonica

The Japanese eel(Anguilla japonica)is a commercially important fi sh species in East Asia and its recruitment has been rapidly declining since 1990s.Clarifying the genetic population structure of A.japonica is the basis of multinational cooperation on its management and protection,due to its large distribution range.Gene-associated markers have been proved powerful in delineating fi ne-scale population genetic structure and spatially varying selection.In the present study,we developed 24 polymorphic gene-associated microsatellite markers including 18 loci associated with the genes under selection in the two North Atlantic eel species(Anguilla anguilla and Anguilla rostrata)and 6 loci based on transcript sequences.A total of 13 geographic populations were sampled across its distribution range,including 11 samples from China(9 from China’s mainland and 2 from Taiwan region),and 2 samples from Japan.A total of 416 individuals(mostly glass eels)were collected and genotyped at the 24 microsatellites.All measures of diff erentiation were accordant with a panmictic scenario(F ST=-0.001)in A.japonica.No footprints of spatially varying selection were found,indicating that the selection pattern in A.japonica might be diff erent from that in the two North Atlantic eel species.We suggest that A.japonica should be managed as a single unit and management and conservation eff orts must be coordinated at the international level,as overexploitation in any region will decrease its recruitment across the whole distributional range.

Optically spatial information selection with hybridly polarized beam in atomic vapor

Vector beams with spatially variant polarization have attracted much attention in recent years, with potential applications in both classical optics and quantum optics. In this work, we study a polarization selection of spatial intensity distribution by utilizing a hybridly polarized beam as a coupling beam and a circularly polarized beam as a probe beam in87 Rb atom vapor. We experimentally observe that the spatial intensity distribution of the probe beam after passing through atoms can be modulated by the hybridly polarized beam due to the optical pumping effect. Then, the information loaded in the probe beam can be designedly filtrated by an atomic system with a high extinction ratio. A detailed process of the optical pumping effect in our configurations and the corresponding absorption spectra are presented to interpret our experimental results, which can be used for the spatial optical information locally extracted based on an atomic system, which has potential applications in quantum communication and computation.

Decline of selectivity of V1 neurons to visual stimulus spatial frequencies in old cats

Objective To examine whether the selectivity of visual cortical neurons to stimulus spatial frequencies would be affected by aging in cats.Methods In vivo extracellular single-unit recording techniques were employed to record the tuning responses of V1 neurons to different stimulus spatial frequencies in old and young adult cats.Results Statistical analysis showed that the mean optimal spatial frequency of grating stimuli that evoked the maximal response of V1 neurons in old cats was significantly lower than that in young adult cats.Furthermore,the mean high cut-off spatial frequency of grating stimuli that evoked the half amplitude of the maximal response of V1 neurons in old cats was also significantly lower than that in young adult cats.Conclusion These results are consistent with those reported in the V1 of old monkeys,suggesting that the age-related decline in the selectivity of visual cortical cells to spatial frequency could be generalized to all mammalian species and might contribute to visual acuity reduction in senescent individuals.

Neural mechanisms of top-down divided and selective spatial attention in visual and auditory perception

Top-down attention mechanisms require the selection of specificobjects or locations;however,the brain mechanism involved when attention is allocated across different modalities is not well understood.The aim of this study was to use functional magnetic resonance imaging to define the neural mechanisms underlyingdivided and selective spatial attention.A concurrent audiovisual stimulus was used,and subjects were prompted to focus on a visual,auditory and audiovisual stimulus in a Posner paradigm.Ourbehavioral results confirmed the better performance of selectiveattention compared to devided attention.We found differences in the activation level of the frontoparietal network,visual/auditorycortex,the putamen and the salience network under differentattention conditions.We further used Granger causality(GC)toexplore effective connectivity differences between tasks.Differences in GC connectivity between visual and auditory selective tasksreflected the visual dominance effect under spatial attention.In addition,our results supported the role of the putamen inredistributing attention and the functional separation of the saliencenetwork.In summary,we explored the audiovisual top-down allocation of attention and observed the differences in neuralmechanisms under endogenous attention modes,which revealedthe differences in cross-modal expression in visual and auditory attention under attentional modulation.

空间选择性缺陷管理制备高性能碳基CsPbI_(3)钙钛矿太阳能电池

Defects formed at the surface,buried interface and grain boundaries(GB)of CsPbI_(3)perovskite films considerably limit photovoltaic performance.Such defects could be passivated effectively by the most prevalent post modification strategy without compromising the photoelectric properties of perovskite films,but it is still a great challenge to make this strategy comprehensive to different defects spatially distributed throughout the films.Herein,a spatially selective defect management(SSDM)strategy is developed to roundly passivate various defects at different locations within the perovskite film by a facile one-step treatment procedure using a piperazine-1,4-diium tetrafluoroborate(PZD(BF_(4))_(2))solution.The small-size PZD^(2+)cations could penetrate into the film interior and even make it all the way to the buried interface of CsPbI_(3)perovskite films,while the BF_(4)^(-)anions,with largely different properties from I^(-)anions,mainly anchor on the film surface.Consequently,virtually all the defects at the surface,buried interface and grain boundaries of CsPbI_(3)perovskite films are effectively healed,leading to significantly improved film quality,enhanced phase stability,optimized energy level alignment and promoted carrier transport.With these films,the fabricated CsPbI_(3)PSCs based on carbon electrode(C-PSCs)achieve an efficiency of18.27%,which is among the highest-reported values for inorganic C-PSCs,and stability of 500 h at 85℃with 65%efficiency maintenance.

Wavefront-selective Fano resonant metasurfaces

Fano resonances are conventionally understood as sharp spectral features with selectivity in the momentum-frequency domain,implying that they can be excited only by plane waves with specific frequencies and incident angles.We demonstrate that Fano resonances can be made generally selective in the spacefrequency domain.They can be tailored to resonate only when excited by a frequency,polarization,and wavefront of choice.This generalization reveals that Fano systems are characterized by eigenwaves that scatter to their time-reversed image upon reflection.Although in conventional Fano systems this trivially occurs for normally incident plane waves,we show that,in general,the selected wavefront is locally retroreflected everywhere across the device.These results show that conventional Fano resonances are a subset of a broader dichroic phenomenon with spin,spatial,and spectral selectivity.We demonstrate these concepts with nonlocal metasurfaces whose governing principles are deeply rooted in the symmetry features of quasi-bound states in the continuum.Enhanced light–matter interactions and symmetry-protection make these phenomena uniquely suited for enriching applications in quantum optics,non-linear optics,augmented reality,and secure optical communications,laying the groundwork for a range of novel compact optical sources and devices.

Chaff Cloud Jamming Suppression Based on Wavelet Transform

Radar target signals and chaff cloud jamming signals have different characters by the wavelet transform.The wavelet coefficients of radar target signals are highly correlated with its near-and-near-scale wavelet coefficients,however the correlativity between the wavelet coefficients of chaff cloud jamming signals and its nearand-near scale wavelet coefficients is less significant.Based on the binary-base discrete wavelet transform and the correlation algorithm,the method of target entropy to estimate standard variance of the jamming signals and each scale is proposed to ensure reasonable threshold,to suppress chaff cloud signals and finally to reconstruct mixed signals by the improved spatially selective noise filtration(ISSNF) method.The extensive simulation results show that the proposed method can availably suppress chaff cloud jamming and decontaminate target echo.