High-resolution Image Analysis Research Articles

Feature Selection for Object-Based Classification of High-Resolution Remote Sensing Images Based on the Combination of a Genetic Algorithm and Tabu Search.

In object-based image analysis of high-resolution images, the number of features can reach hundreds, so it is necessary to perform feature reduction prior to classification. In this paper, a feature selection method based on the combination of a genetic algorithm (GA) and tabu search (TS) is presented. The proposed GATS method aims to reduce the premature convergence of the GA by the use of TS. A prematurity index is first defined to judge the convergence situation during the search. When premature convergence does take place, an improved mutation operator is executed, in which TS is performed on individuals with higher fitness values. As for the other individuals with lower fitness values, mutation with a higher probability is carried out. Experiments using the proposed GATS feature selection method and three other methods, a standard GA, the multistart TS method, and ReliefF, were conducted on WorldView-2 and QuickBird images. The experimental results showed that the proposed method outperforms the other methods in terms of the final classification accuracy.

Strain in Ultrathin SiGeSn Layers in a Silicon Matrix

Strain in SiGeSn alloy layers with thicknesses of d = 1.5 and 2.0 nm grown in a Si matrix by molecular-beam epitaxy is investigated using the geometric-phase analysis of high-resolution electron microscopy images. The layer thickness is comparable to the spatial resolution of the method (Δ ~ 1 nm), which leads to a considerable distortion of the strain distribution profile and an error in determining the strain value. A correction to the measured strain making it closer to the true value is obtained by comparing the shapes of the observed and real strain distributions in the investigated layers. The correction is determined by the Δ/d ratio. The found strain values are in good agreement with the calculations for pseudomorphic layers in the model of a rigid substrate.

Improved Water-Resistance Test Methods Utilizing a Multispectral Imaging System to Quantify Black and Color Ink Bleeding for Plain Paper Office and Legal Documents Printed with Pigment- and Dye-Based Inkjet Inks

Current ISO standards that pertain to water-resistance testing with inkjet prints were developed for moisture-impermeable RC photo papers and do not take into account the kinds of ink diffusion behavior that can occur with inkjet printing on highly absorbent plain papers, especially with dye-based inks. Contact with water with plain paper documents can result in significant lateral ink bleeding, migration of inks through the paper to the backside of the sheet, transfer of ink from one sheet to adjacent sheets, and two-way transfer of inks with double-sided printed documents. Shipping labels and envelopes can become illegible should they become wet, and Barcodes and QR codes may be rendered completely unreadable. This study attempts to better understand the water-resistance behavior of plain paper documents printed with dye-based and pigment inkjet inks. The use of high-resolution multispectral imaging and colorimetric analysis systems to provide a quantitative assessment of ink bleeding, migration, and ink transfer to adjacent pages is explored as an alternative to the subjective, qualitative, water-resistance evaluation methods specified in current ISO standards.

Determination of thermal diffusivity of persimmon flesh tissue using three-dimensional structure model based on X-ray computed tomography

Computed tomography (CT) images were acquired for an intact fruit and the cell tissues of persimmon flesh using two types of X-ray CT devices. The relationship between the porosity and mean CT value for small tissue samples having a volume of 0.3 mm × 0.3 mm × 0.3 mm was investigated. The three-dimensional microstructure of the issue was reconstructed using image processing software and heat transfer simulation was carried out based on the real structure model. The effective thermal conductivity of the tissue was determined by comparing the results of the three-dimensional (3D) model simulation with those of the homogeneous model simulation and was related to the porosity of the sample. The Brailsford model was selected as the most suitable model to predict the effective thermal conductivity of the tissue. The porosity, thermal conductivity and moisture distributions were visualized for an intact fruit based on analysis of high-resolution X-ray image.

Network-based approaches to quantify multicellular development.

Multicellularity and cellular cooperation confer novel functions on organs following a structure–function relationship. How regulated cell migration, division and differentiation events generate cellular arrangements has been investigated, providing insight into the regulation of genetically encoded patterning processes. Much less is known about the higher-order properties of cellular organization within organs, and how their functional coordination through global spatial relations shape and constrain organ function. Key questions to be addressed include: why are cells organized in the way they are? What is the significance of the patterns of cellular organization selected for by evolution? What other configurations are possible? These may be addressed through a combination of global cellular interaction mapping and network science to uncover the relationship between organ structure and function. Using this approach, global cellular organization can be discretized and analysed, providing a quantitative framework to explore developmental processes. Each of the local and global properties of integrated multicellular systems can be analysed and compared across different tissues and models in discrete terms. Advances in high-resolution microscopy and image analysis continue to make cellular interaction mapping possible in an increasing variety of biological systems and tissues, broadening the further potential application of this approach. Understanding the higher-order properties of complex cellular assemblies provides the opportunity to explore the evolution and constraints of cell organization, establishing structure–function relationships that can guide future organ design.

Azimuthally anisotropic hydride lens structures in Zircaloy 4 nuclear fuel cladding: High-resolution neutron radiography imaging and BISON finite element analysis

High-resolution neutron radiography has been used to image bulk circumferential hydride lens particles in unirradiated Zircaloy 4 tubing cross section specimens. Zircaloy 4 is a common light water nuclear reactor (LWR) fuel cladding; hydrogen pickup, hydride formation, and the concomitant effect on the mechanical response are important for LWR applications. Ring cross section specimens with three hydrogen concentrations (460, 950, and 2830 parts per million by weight) and an as-received reference specimen were imaged. Azimuthally anisotropic hydride lens particles were observed at 950 and 2830 wppm. The BISON finite element analysis nuclear fuel performance code was used to model the system elastic response induced by hydride volumetric dilatation. The compressive hoop stress within the lens structure becomes azimuthally anisotropic at high hydrogen concentrations or high hydride phase fraction. This compressive stress anisotropy matches the observed lens anisotropy, implicating the effect of stress on hydride formation as the cause of the observed lens azimuthal asymmetry. The cause and effect relation between compressive stress and hydride lens anisotropy represents an indirect validation of a key BISON output, the evolved hoop stress associated with hydride formation.

Endodermal germ-layer formation through active actin-driven migration triggered by N-cadherin

Germ-layer formation during gastrulation is both a fundamental step of development and a paradigm for tissue formation and remodeling. However, the cellular and molecular basis of germ-layer segregation is poorly understood, mostly because of the lack of direct in vivo observations. We used mosaic zebrafish embryos to investigate the formation of the endoderm. High-resolution live imaging and functional analyses revealed that endodermal cells reach their characteristic innermost position through an active, oriented, and actin-based migration dependent on Rac1, which contrasts with the previously proposed differential adhesion cell sorting. Rather than being attracted to their destination, the yolk syncytial layer, cells appear to migrate away from their neighbors. This migration depends on N-cadherin that, when imposed in ectodermal cells, is sufficient to trigger their internalization without affecting their fate. Overall, these results lead to a model of germ-layer formation in which, upon N-cadherin expression, endodermal cells actively migrate away from their epiblastic neighbors to reach their internal position, revealing cell-contact avoidance as an unexplored mechanism driving germ-layer formation.

High resolution imaging analysis of female carriers and patients of Choroideremia with CHM gene mutation

PurposeTo report the high resolution imaging features of Japanese patient and female carriers of choroideremia using adaptive optics(AO) and other imaging modalities.MethodsThree carriers and one patient underwent comprehensive examinations including AO fundus camera (rtx1™ Imagine eyes, France), spectral domain optical coherence topography (SD‐OCT)and fundus autofluoresence (FAF). Cone density was measured by peak density method and compared with the data of 34 normal controls. The mutation analysis of the CHM gene was performed by Sanger sequencing. The protocol conformed to the tenets of the Declaration of Helsinki and was approved by the IRB of The Jikei University and Nippon Medical School.ResultsThree female carriers 1, 2, 3 (sister 9 y.o, mother 37 y.o and grandmother 65 y.o) and one patient (6 y.o, male). They had same CHM mutation, c.646delA, p.T216LfsX16. All carriers did not complain any symptoms, the BCVA of all were over 20/20. Fundus examination of carrier 2 showed mild generation in only periphery, the other carriers showed diffuse degeneration. AF showed mottled hypo‐autofluoresence in degeneration area. SD‐OCT of the carriers showed nearly normal,although peripheral SD‐OCT and patient showed diffuse disruptions of interdigitation and ellipsoid zones.Cone density was measured at 2 to 8 degree temporal from the fovea in every 1 degree, using 50 x 50 micron images. Cone counting was performed by AO detect (Imagine eyes) with manual correction. Patient showed lower cone density more than 2 SD of normal control. The carriers showed lower cone density only at 7 and 8 degrees.ConclusionsAO cone counting showed reduction of photoreceptors in carriers mainly at peripheral region. To elucidate the mechanism of peripheral degeneration and foveal sparing of female carriers may help preventing the disease progression of choroideremia patients.

Dislocation-free axial InAs-on-GaAs nanowires on silicon

We report on the growth of axial InAs-on-GaAs nanowire heterostructures on silicon by molecular beam epitaxy using 20 nm diameter Au catalysts. First, the growth parameters of the GaAs nanowire segment were optimized to achieve a pure wurtzite crystal structure. Then, we developed a two-step growth procedure to enhance the yield of vertical InAs-on-GaAs nanowires. We achieved 90% of straight InAs-on-GaAs nanowires by further optimizing the growth parameters. We investigated the composition change at the interface by energy dispersive x-ray spectroscopy and the nanowire crystal structure by transmission electron microscopy. The composition of the nominal InAs segment is found to be InxGa1−xAs with x = 0.85 and corresponds to 6% of lattice mismatch with GaAs. Strain mapping performed by the geometrical phase analysis of high-resolution images revealed a dislocation-free GaAs/In0.85Ga0.15As interface. In conclusion, we successfully fabricated highly mismatched heterostructures, confirming the prediction that axial GaAs/In0.85Ga0.15As interfaces are pseudomorphic in nanowires with a diameter smaller than 40 nm.

The Star Blended with the MOA-2008-BLG-310 Source Is Not the Exoplanet Host Star

Abstract High-resolution Hubble Space Telescope (HST) image analysis of the MOA-2008-BLG-310 microlens system indicates that the excess flux at the location of the source found in the discovery paper cannot primarily be due to the lens star because it does not match the lens–source relative proper motion, , predicted by the microlens models. This excess flux is most likely to be due to an unrelated star that happens to be located in close proximity to the source star. Two epochs of HST observations indicate proper motion for this blend star that is typical of a random bulge star but is not consistent with a companion to the source or lens stars if the flux is dominated by only one star, aside from the lens. We consider models in which the excess flux is due to a combination of an unrelated star and the lens star, and this yields a 95% confidence level upper limit on the lens star brightness of and . A Bayesian analysis using a standard Galactic model and these magnitude limits yields a host star mass of and a planet mass of at a projected separation of au. This result illustrates that excess flux in a high-resolution image of a microlens–source system need not be due to the lens. It is important to check that the lens–source relative proper motion is consistent with the microlensing prediction. The high-resolution image analysis techniques developed in this paper can be used to verify the WFIRST exoplanet microlensing survey mass measurements.

Imaging and reconstruction of cell cortex structures near the cell surface

Total internal reflection fluorescence microscopy (TIRFM) provides high optical sectioning capability and superb signal-to-noise ratio for imaging of cell cortex structures. The development of multi-angle (MA)-TIRFM permits high axial resolution imaging and reconstruction of cellular structures near the cell surface. Cytoskeleton is composed of a network of filaments, which are important for maintenance of cell function. The high-resolution imaging and quantitative analysis of filament organization would contribute to our understanding of cytoskeleton regulation in cell. Here, we used a custom-developed MA-TIRFM setup, together with stochastic photobleaching and single molecule localization method, to enhance the lateral resolution of TIRFM imaging to about 100 nm. In addition, we proposed novel methods to perform filament segmentation and 3D reconstruction from MA-TIRFM images. Furthermore, we applied these methods to study the 3D localization of cortical actin and microtubule structures in U373 cancer cells. Our results showed that cortical actins localize ∼27 nm closer to the plasma membrane when compared with microtubules. We found that treatment of cells with chemotherapy drugs nocodazole and cytochalasin B disassembles cytoskeletal network and induces the reorganization of filaments towards the cell periphery. In summary, this study provides feasible approaches for 3D imaging and analyzing cell surface distribution of cytoskeletal network. Our established microscopy platform and image analysis toolkits would facilitate the study of cytoskeletal network in cells.

More features, more tools, moreCrysTBox

A new release of theCrysTBoxsoftware is introduced. The original toolbox allows for an automated analysis of transmission electron microscope (TEM) images and for crystallographic visualization. The existing tools, which are capable of highly precise analyses of high-resolution TEM images, as well as spot, disc and ring diffraction patterns, are extended to include a tool for automatically measuring TEM sample thickness using convergent beam electron diffraction in a two-beam approximation. An implementation of geometric phase analysis is newly available, employing one of the existing tools to identify parameters and indices of crystallographic planes depicted in the input image and allowing easier and more accurate analysis. The crystallographic visualization capabilities are extended as well. Along with the simulated diffraction pattern and atomic structure, a stereographic projection and inverse pole figure tool is newly offered. A new tool able to visualize the atomic structure of two different phases and their interface is also introduced.

Effects of BOW Model With Affinity Propagation and Spatial Pyramid Matching on Polarimetric SAR Image Classification

The bag of visual words (BOW) model has attracted a great deal of attention in high-resolution remote sensing image classification. Related studies based on polarimetric synthetic aperture radar (PolSAR) image classification are also still challenging. This paper presents a new method of PolSAR image classification based on the BOW model and supplemented by an affinity propagation clustering algorithm (AP), as well as a spatial pyramid matching (SPM) technique (AP_SPM_BOW). Its classification effect is analyzed compared to those of BOW models with other clustering algorithms (e.g., K -means, meanshift, Gaussian mixture model), as well as the ML classification method by using two types of PolSAR images with different resolutions collected from EMISAR and RADARSAT-2 sensors. These results demonstrate that the proposed AP_SPM_BOW model is not only a stable and effective tool for PolSAR image classification but also more suitable for the analysis of high-resolution PolSAR images. In addition, the use of polarimetric information in BOW models can effectively improve the classification accuracy.

ISDoT: in situ decellularization of tissues for high-resolution imaging and proteomic analysis of native extracellular matrix.

The extracellular matrix (ECM) is a master regulator of cellular phenotype and behavior. It has a crucial role in both normal tissue homeostasis and disease pathology. Here we present a fast and efficient approach to enhance the study of ECM composition and structure. Termed in situ decellularization of tissues (ISDoT), it allows whole organs to be decellularized, leaving native ECM architecture intact. These three-dimensional decellularized tissues can be studied using high-resolution fluorescence and second harmonic imaging, and can be used for quantitative proteomic interrogation of the ECM. Our method is superior to other methods tested in its ability to preserve the structural integrity of the ECM, facilitate high-resolution imaging and quantitatively detect ECM proteins. In particular, we performed high-resolution sub-micron imaging of matrix topography in normal tissue and over the course of primary tumor development and progression to metastasis in mice, providing the first detailed imaging of the metastatic niche. These data show that cancer-driven ECM remodeling is organ specific, and that it is accompanied by comprehensive changes in ECM composition and topological structure. We also describe differing patterns of basement-membrane organization surrounding different types of blood vessels in healthy and diseased tissues. The ISDoT procedure allows for the study of native ECM structure under normal and pathological conditions in unprecedented detail.

SPECTRUM, VELOCITY AND DRIFT OF DROPLETS SPRAYED BY NOZZLES WITH AND WITHOUT AIR INDUCTION AND MINERAL OIL

ABSTRACT The aim of this study was to evaluate the spectrum, the velocity and the potential drift risk of droplets sprayed by nozzles with and without air induction, with the addition of mineral oil to the spray solution. The experiment was conducted in a completely randomized design with five replications; in a factorial model 2 × 2 (two spray nozzles and spray solution with and without mineral oil Assist®). Spray nozzles with and without air induction were evaluated, with nominal flow rate of 1.14 L min−1 and pressure of 300 kPa. The spectrum and the velocity of droplets were evaluated directly, using a droplet analyzer (VisiSize D30) in real time based on the analysis of high-resolution images. The drift potential was evaluated in an open circuit wind tunnel. The data were submitted to analysis of variance and comparison test. In general, the addition of mineral oil (1.5% V V−1) resulted in an increase in the velocity of droplets, reduced drift and more homogeneous droplet spectrum. Air induction nozzles promoted larger and less homogeneous droplets, but they little affected the velocity of the droplets. There is an inverse correlation between drift potential and volume median diameter (VMD), which indicates that VMD can be used to predict the behavior of drift risk.

High-Resolution 3D FIB-SEM Image Analysis and Validation of Numerical Simulations of Nanometre-Scale Porous Ceramic with Comparisons to Experimental Results

The development of focused ion beam-scanning electron microscopy (FIB-SEM) techniques has allowed high-resolution 3D imaging of nanometre-scale porous materials. These systems are of important interest to the oil and gas sector, as well as for the safe long-term storage of carbon and nuclear waste. This work focuses on validating the accurate representation of sample pore space in FIB-SEM-reconstructed volumes and the predicted permeability of these systems from subsequent single-phase flow simulations using a highly homogeneous nanometre-scale, mesoporous (2–50 nm) to macroporous (>50 nm), porous ceramic in initial developments for digital rock physics. The limited volume of investigation available from FIB-SEM has precluded direct quantitative validation of petrophysical parameters estimated from such studies on rock samples due to sample heterogeneity, large variations in recorded sample pore sizes and lack of pore connectivity. By using homogeneous synthetic ceramic samples we have shown that lattice-Boltzmann flow simulations using processed FIB-SEM images are capable of predicting the permeability of a homogeneous material dominated by 10–100 nanometre-scale pores (similar, albeit simpler, to those in natural samples) at the much larger scale where permeability measurements become practical. This result shows the LB flow simulations can be used with confidence in pores at this scale allowing future work to focus on sample preparation techniques for samples sensitive to drying and multiple FIB-SEM site selection for the population of larger-scale models for heterogeneous systems.

A fast alternative to three- and four-component scattering models for polarimetric SAR image decomposition

ABSTRACTModel-based decomposition techniques are widely used for extraction of information from polarimetric synthetic aperture radar (PolSAR) images. The solution of almost all the model-based decomposition methods is based on an assumption. The reason for this is that these models have more number of unknowns than the number of equations. In this paper, we present a fast alternative approach to solve the conventional three- and four-component model-based decomposition methods. Utilizing the matrix rotation theory, we have proposed coherency matrix transformations by two new rotation matrices. After the proposed transformations, the dependency of two unknowns on element of coherency matrix vanishes, so that the number of unknowns become equal to number of equations. This makes the proposed decomposition techniques computationally efficient and more suitable for the analysis of high resolution images where the number of pixels are quite large.

Quantitative Image Analysis For Geologic Core Description

Abstract: Many basic rock properties—such as lithology, bedding, grain size, sorting, and porosity—are expressed in geologic cores by changes in color, brightness, and texture. Quantitative descriptive rock properties can thus be derived from digital core images. Despite the widespread availability of high-resolution core images and image analysis software, these data are underutilized by geoscientists tasked with describing core. This paper demonstrates the application of image analysis for quantitative core description using examples from three different carbonate reservoirs: (1) evaporite-rich dolostone from the First Eocene, Kuwait–Saudi Arabia Partitioned Zone, (2) vuggy dolostone from the Cretaceous Toca Formation, offshore Angola, (3) thin-bedded limestone and mudrock from the Ordovician Utica Formation, Ohio, USA. In each example, quantitative data are extracted from core images using ImageJ or WellCAD software. The image-derived descriptive parameters are consistent with petrophysical log and core data, supporting the validity of this approach to core description. Image-analysis-guided core description offers many advantages over traditional hand-drawn core description: 1) hand-drawn core descriptions tend to be qualitative and core-log integration is difficult and imprecise, whereas image analysis generates quantitative descriptive data that are directly comparable with petrophysical datasets; 2) image analysis can characterize fine-scale geologic heterogeneity that is difficult or impossible to resolve using log and core plug data and hand-drawn core descriptions; 3) image analysis allows geologists to generate preliminary descriptions prior to actual core viewing, a more efficient workflow that minimizes time expended in offsite core viewing, perhaps in remote locations with limited time available; 4) integration of image-derived core data with petrophysical log and core data allows rigorous evaluation of core data quality—before, during, and after the process of core description. Image analysis thus provides a valuable tool for geoscientists to efficiently generate quantitative, petrophysically significant core descriptions.

High-resolution dynamic imaging and quantitative analysis of lung cancer xenografts in nude mice using clinical PET/CT.

Considering the general application of dedicated small-animal positron emission tomography/computed tomography is limited, an acceptable alternative in many situations might be clinical PET/CT. To estimate the feasibility of using clinical PET/CT with [F-18]-fluoro-2-deoxy-D-glucose for high-resolution dynamic imaging and quantitative analysis of cancer xenografts in nude mice. Dynamic clinical PET/CT scans were performed on xenografts for 60 min after injection with [F-18]-fluoro-2-deoxy-D-glucose. Scans were reconstructed with or without SharpIR method in two phases. And mice were sacrificed to extracting major organs and tumors, using ex vivo γ-counting as a reference. Strikingly, we observed that the image quality and the correlation between the all quantitive data from clinical PET/CT and the ex vivo counting was better with the SharpIR reconstructions than without. Our data demonstrate that clinical PET/CT scanner with SharpIR reconstruction is a valuable tool for imaging small animals in preclinical cancer research, offering dynamic imaging parameters, good image quality and accurate data quatification.

Efficacy comparison of Accell Evo3 and Grafton demineralized bone matrix putties against autologous bone in a rat posterolateral spine fusion model

Background ContextSpinal fusion procedures are intended to stabilize the spinal column for a multitude of disorders including abnormal curvature, traumatic instability, degenerative instability, and damage from infections or tumors. As an aid in the bone healing response, bone graft materials are used to bridge joints for arthrodesis and promote unions in pseudoarthrosis. Currently, the gold standard for stabilizing fusion masses in spinal procedures involves using the osteogenic, osteoinductive, and osteoconductive properties of autologous iliac crest corticocancellous bone. However, considerable morbidity is associated with harvesting the autologous graft. Donor site complications including infection, large hematomas, and pain have been reported at rates as high as 50% (Boden and Jeffrey, 1995). Biologically, the rate of bone repair dictates the rate at which the fusion mass will unite under autologous graft conditions. PurposeThe purpose of this study is to compare the quality and rate of fusion between Accell Evo3 and Grafton demineralized bone matrix (DBM), with the gold standard iliac crest bone graft (ICBG) as the control, in athymic rat posterolateral fusion. Study DesignThis study was a randomized, controlled study in a laboratory setting at the Hospital for Special Surgery in New York City. Blinded observations were made, which created an assessment of outcomes for successful fusions between each method. Patient SampleForty-eight (48) athymic rats were used in this study and underwent posterolateral lumbar fusion. They were assessed at either 3 weeks or 9 weeks to see the rate and efficacy of fusion. Outcome MeasuresOutcome measures will be the efficacy of the different bone grafts and their success rates of fusion in the rats. MethodsA comparison of the quality and rate of fusion between Accell Evo3® (DBM A) and Grafton (DBM B), with the gold standard iliac crest bone graft (ICBG) as the control, was performed using the established posterolateral intertransverse process on an athymic rat model. Materials were evaluated for fusion by several criteria, including manual palpation, standard and high-resolution radiographic imaging, micro-computed topography, and histologic analysis. Forty-eight (48) athymic rats received a bilateral intertransverse process fusion, using either bone from the iliac crest (control group), Accell Evo3, or Grafton. Twelve (12) rats (four from each group) were sacrificed at 3 weeks postoperatively, whereas the remaining thirty-six (36) were sacrificed at 9 weeks postoperatively. Three blinded observers examined the spines after the rats were euthanized, and they blindly assessed each rat for fusion success. ResultsManual palpation of the three different groups at 3 weeks postoperatively found successful fusion in 1 of 4 (25%) of the autologous bone graft (ABG) group and 4 of 4 (100%) of both DBM A and B groups. Manual palpation of the remaining animals that were sacrificed at 9 weeks postoperatively showed successful fusion in 4 of 12 (33%) of the ABG group, 8 of 12 (66%) of the DBM A group, and 12 of 12 (100%) of the DBM B group. Radiography found that 9 of 16 (56%) of the ABG group and 16 of 16 (100%) of both DBM Putty A and B groups had fused. Histologic analysis of the ABG group demonstrated less mature and less organized osteoid at both 3 and 9 weeks than the DBM Putty A and B groups. Nondestructive mechanical testing demonstrated increased stiffness in 4-point bending of both DBM A and B compared with ABG. ConclusionsBoth DBM-treated groups achieved a significantly higher rate of fusion than the ABG-treated group at 9 weeks in this model. Successful fusion was also demonstrated in the DBM-treated groups at 3 weeks.