Analysis Of Intensity Distribution Research Articles

A high-speed particle phase discriminator (PPD-HS) for the classification of airborne particles, as tested in a continuous flow diffusion chamber

Abstract. A new instrument, the High-speed Particle Phase Discriminator (PPD-HS), developed at the University of Hertfordshire, for sizing individual cloud hydrometeors and determining their phase is described herein. PPD-HS performs an in situ analysis of the spatial intensity distribution of near-forward scattered light for individual hydrometeors yielding shape properties. Discrimination of spherical and aspherical particles is based on an analysis of the symmetry of the recorded scattering patterns. Scattering patterns are collected onto two linear detector arrays, reducing the complete 2-D scattering pattern to scattered light intensities captured onto two linear, one-dimensional strips of light sensitive pixels. Using this reduced scattering information, we calculate symmetry indicators that are used for particle shape and ultimately phase analysis. This reduction of information allows for detection rates of a few hundred particles per second. Here, we present a comprehensive analysis of instrument performance using both spherical and aspherical particles generated in a well-controlled laboratory setting using a vibrating orifice aerosol generator (VOAG) and covering a size range of approximately 3–32 µm. We use supervised machine learning to train a random forest model on the VOAG data sets that can be used to classify any particles detected by PPD-HS. Classification results show that the PPD-HS can successfully discriminate between spherical and aspherical particles, with misclassification below 5 % for diameters >3 µm. This phase discrimination method is subsequently applied to classify simulated cloud particles produced in a continuous flow diffusion chamber setup. We report observations of small, near-spherical ice crystals at early stages of the ice nucleation experiments, where shape analysis fails to correctly determine the particle phase. Nevertheless, in the case of simultaneous presence of cloud droplets and ice crystals, the introduced particle shape indicators allow for a clear distinction between these two classes, independent of optical particle size. From our laboratory experiments we conclude that PPD-HS constitutes a powerful new instrument to size and discriminate the phase of cloud hydrometeors. The working principle of PPD-HS forms a basis for future instruments to study microphysical properties of atmospheric mixed-phase clouds that represent a major source of uncertainty in aerosol-indirect effect for future climate projections.

Evaluation of Temporal Aggregation Processes Using Spatial Intensity Distribution Analysis.

Small proteinaceous oligomeric species contribute to the formation of larger aggregates, a phenomenon that is of direct relevance to the characterization of protein aggregation in biopharmaceuticals and understanding the underlying processes contributing to neurodegenerative diseases.The ability to monitor in situ oligomerization and aggregation processes renders imaging and image analysis an attractive approach for gaining a mechanistic insight into early processes contributing to the formation of larger aggregates in disease models and biologics. The combination of image analysis tools enables the detection of both oligomeric and larger aggregate subtype in contrast to conventional kinetic-based approaches that lack the ability to resolve dimers from monomeric moieties in samples containing mixed populations.In this chapter, we describe the process for confocal time series image acquisition for monitoring the in situ loss of monomers, and the subsequent analysis pipeline using spatial intensity distribution analysis (SpIDA) to evaluate oligomer content.

Analysis of Intensity Distribution in the He-Ne Laser Beam by Gaussian Distribution Function

The purpose of this research is to analyze the distribution of density in the laser beam, both from the experimental and theoretical point of view. I measured the density distribution through the He-Ne laser beam and prepared an attempt to compare it with the Gaussian distribution function. Image profiling can be used to determine the distance of objects depending on the distribution of the laser beam spot surroundings by their width. It can also be used to take pictures of things and define their distances and shape things. As we see, Nubia is very good. From the compatibility analysis found that (the program that made the fitting mention of GNUPLOT).

From LiDAR Waveforms to Hyper Point Clouds: A Novel Data Product to Characterize Vegetation Structure

Full waveform (FW) LiDAR holds great potential for retrieving vegetation structure parameters at a high level of detail, but this prospect is constrained by practical factors such as the lack of available handy processing tools and the technical intricacy of waveform processing. This study introduces a new product named the Hyper Point Cloud (HPC), derived from FW LiDAR data, and explores its potential applications, such as tree crown delineation using the HPC-based intensity and percentile height (PH) surfaces, which shows promise as a solution to the constraints of using FW LiDAR data. The results of the HPC present a new direction for handling FW LiDAR data and offer prospects for studying the mid-story and understory of vegetation with high point density (~182 points/m2). The intensity-derived digital surface model (DSM) generated from the HPC shows that the ground region has higher maximum intensity (MAXI) and mean intensity (MI) than the vegetation region, while having lower total intensity (TI) and number of intensities (NI) at a given grid cell. Our analysis of intensity distribution contours at the individual tree level exhibit similar patterns, indicating that the MAXI and MI decrease from the tree crown center to the tree boundary, while a rising trend is observed for TI and NI. These intensity variable contours provide a theoretical justification for using HPC-based intensity surfaces to segment tree crowns and exploit their potential for extracting tree attributes. The HPC-based intensity surfaces and the HPC-based PH Canopy Height Models (CHM) demonstrate promising tree segmentation results comparable to the LiDAR-derived CHM for estimating tree attributes such as tree locations, crown widths and tree heights. We envision that products such as the HPC and the HPC-based intensity and height surfaces introduced in this study can open new perspectives for the use of FW LiDAR data and alleviate the technical barrier of exploring FW LiDAR data for detailed vegetation structure characterization.

Capabilities of X-ray diffuse scattering method for study of microdefects in semiconductor crystals

The capabilities of X-ray diffuse scattering (XRDS) method for the study of microdefects in semiconductor crystals have been overviewed. Analysis of the results has shown that the XRDS method is a highly sensitive and information valuable tool for studying early stages of solid solution decomposition in semiconductors. A review of the results relating to the methodological aspect has shown that the most consistent approach is a combination of XRDS with precision lattice parameter measurements. It allows one to detect decomposition stages that cannot be visualized using transmission electron microscopy (TEM) and moreover to draw conclusions as to microdefect formation mechanisms. TEM-invisible defects that are coherent with the matrix and have smeared boundaries with low displacement field gradients may form due to transmutation doping as a result of neutron irradiation and relaxation of disordered regions accompanied by redistribution of point defects and annihilation of interstitial defects and vacancies. For GaP and InP examples, a structural microdefect formation mechanism has been revealed associated with the interaction of defects forming during the decomposition and residual intrinsic defects. Analysis of XRDS intensity distribution around the reciprocal lattice site and the related evolution of lattice constant allows detecting different decomposition stages: first, the formation of a solution of Frenkel pairs in which concentration fluctuations develop, then the formation of matrix-coherent microdefects and finally coherency violation and the formation of defects with sharp boundaries. Fundamentally, the latter defects can be precipitating particles. Study of the evolution of diffuse scattering iso-intensity curves in GaP, GaAs(Si) and Si(O) has allowed tracing the evolution of microdefects from matrix-coherent ones to microdefects with smeared coherency resulting from microdefect growth during the decomposition of non-stoichiometric solid solutions heavily supersaturated with intrinsic (or impurity) components.

Study on separation performance of tri-cone water medium cyclone based on CFD

ABSTRACT The present paper investigated the separation performance of tri-cone water medium cyclone and conducted simulation studies on flow field inside cyclone by ANSYS FLUENT, by comparison with that of single-cone cyclone. The separation mechanism was revealed by analysis of internal pressure distribution, speed distribution, turbulence intensity, and density distribution both in tri-cone and single-cone cyclones. Compared with single-cone cyclone, the density distribution of tri-cone cyclone was clearer: Along the center of the cyclone, the density of particles increased outwardly as the radius increased. Along the axial direction of the cyclone, the density of particles gradually increased from top to bottom for the three cones. By experimental study, the separation performance of tri-cone cyclone was better than that of single-cone cyclone, which was caused by much greater turbulence intensity in tri-cone cyclone in the central gas-phase region of the cone. The air drawn in from the underflow port carried the low-density particles in the inner liquid phase from the overflow port upon upward flow, which can improve the separation efficiency.

Determination of the interface parameter in terahertz quantum-cascade laser structures based on transmission electron microscopy

We have determined the interface profiles of GaAs/Al0.25Ga0.75As and GaAs/AlAs terahertz quantum-cascade laser structures using transmission electron microscopy (TEM). The experimental composition profiles are directly extracted from the analysis of the diffracted intensity distribution of g002 dark-field TEM images. Simulated composition profiles, which have been obtained using a Fourier-transform-based model, are in remarkably good agreement with the experimental results so that the determined interface parameter can be used for designing terahertz quantum-cascade lasers. Due to the interface grading, these actual profiles reveal a significantly lower aluminum content of the Al0.25Ga0.75As and AlAs barriers than the nominal values.

Average fractional polarization of extragalactic sources at Planck frequencies

Recent detailed simulations have shown that an insufficiently accurate characterization of the contamination of unresolved polarized extragalactic sources can seriously bias measurements of the primordial cosmic microwave background (CMB) power spectrum if the tensor-to-scalar ratio r ∼ 0.001, as predicted by models currently of special interest (e.g., Starobinsky’s R2 and Higgs inflation). This has motivated a reanalysis of the median polarization fraction of extragalactic sources (radio-loud AGNs and dusty galaxies) using data from the Planck polarization maps. Our approach, exploiting the intensity distribution analysis, mitigates or overcomes the most delicate aspects of earlier analyses based on stacking techniques. By means of simulations, we have shown that the residual noise bias on the median polarization fraction, Πmedian, of extragalactic sources is generally ≲0.1%. For radio sources, we have found Πmedian ≃ 2.83%, with no significant dependence on either frequency or flux density, in good agreement with the earlier estimate and with high-sensitivity measurements in the frequency range 5–40 GHz. No polarization signal is detected in the case of dusty galaxies, implying 90% confidence upper limits of Πdusty ≲ 2.2% at 353 GHz and of ≲3.9% at 217 GHz. The contamination of CMB polarization maps by unresolved point sources is discussed.

Myosin Head Configurations in Resting and Contracting Murine Skeletal Muscle.

Transgenic mouse models have been important tools for studying the relationship of genotype to phenotype for human diseases, including those of skeletal muscle. We show that mouse skeletal muscle can produce high quality X-ray diffraction patterns establishing the mouse intact skeletal muscle X-ray preparation as a potentially powerful tool to test structural hypotheses in health and disease. A notable feature of the mouse model system is the presence of residual myosin layer line intensities in contracting mouse muscle patterns. This provides an additional tool, along with the I1,1/I1,0 intensity ratio, for estimating the proportions of active versus relaxed myosin heads under a given set of conditions that can be used to characterize a given physiological condition or mutant muscle type. We also show that analysis of the myosin layer line intensity distribution, including derivation of the myosin head radius, Rm, may be used to study the role of the super-relaxed state in myosin regulation. When the myosin inhibitor blebbistatin is used to inhibit force production, there is a shift towards a highly quasi-helically ordered configuration that is distinct from the normal resting state, indicating there are more than one helically ordered configuration for resting crossbridges.

Effect of Indole-3-Carbinol on Dimyristoylphosphatidylcholine Multilamellar Vesicles.

This study reports the interaction of indole-3-carbinol (I3C), which is a chemopreventive reagent, with an artificial model membrane {(dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLVs)}, using the intrinsic fluorescence properties of I3C, extrinsic fluorescence properties of Nile Red (NR), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and confocal microscopy. The intrinsic fluorescence of I3C helps to provide information about its location, partitioning ability, and sensitivity toward the phase-transition temperature of liposomes, confirmed by cetylpyridinium chloride (CPC) quenching study, partition coefficient values {(4.60 ± 0.1) × 105 (solid gel phase) and (7.29 ± 0.1) × 105 M-1 (liquid crystalline phase)} and temperature-dependent emission behavior of I3C. I3C perturbs the DMPC MLVs above 15 mol %, as observed using the fluorescence properties of NR, DSC, and DLS data. This perturbation occurs as a consequence of interfacial hydration of the DMPC MLVs, which was clearly indicated by the fluorescence properties (emission intensity, fluorescence lifetime, and nonextensive distribution analysis) of NR.

A cell culture device equipped with a micro-needle electrode array fabricated using backside exposure mold and resin casting.

A cell culture device equipped with a micro-needle electrode array was fabricated for the signal analysis of cell spheroids, cell masses, and cell sheets. For the analysis, sharp needle electrodes with a high aspect ratio for facilitating easy penetration into the cell mass and a small pitch for fine spatial resolution were required. Microelectromechanical systems (MEMS) technology is one of the common solutions for the fabrication of devices. However, an additional process, such as anisotropic etching or electro-polishing, is required for fabricating sharp needles. Tapered needles were fabricated using backside exposure for coating a layer of thick resist film on a glass substrate. The incident beam from mask apertures were diffracted and attenuated in the medium, resulting in tapered intensity distribution. A needle-like shape was obtained after performing resist development without using additional MEMS process. In this study, the theoretical analysis of optical intensity distribution and design and fabrication process of the device were described. Finally, the effectiveness of the device was evaluated by adding cultured cell mass on the needle array. Signals with spikes and fluctuations were observed in the electrode covered with cell mass, whereas only noise was observed on the non-covered electrode, demonstrating the signal pick-up ability of the device during cell culture.

Advancements of the sFIDA method for oligomer-based diagnostics of neurodegenerative diseases.

Early diagnosis of Alzheimer's disease (AD) is of great importance for the development of therapeutics and their application in the clinical environment. Amyloid β (Aβ) oligomers are crucial for the onset and progression of AD and represent a popular drug target, being presumably the most direct biomarker. Efforts to measure Aβ oligomers in body fluids are hampered by the low analyte concentration and presence of Aβ monomers. The surface-based fluorescence intensity distribution analysis (sFIDA) features both highly specific and sensitive oligomer quantitation as well as total insensitivity towards monomers. In this Review, we highlight structural features of oligomeric and fibrillar Aβ. Recent advancements in sFIDA assay development have been the successful automation, adaption for additional biomarkers such as α-synuclein oligomers, and significant improvement of essential assay parameters.

Estimation of the stress level on a cross section of a reinforced concrete beam via Acoustic emission Intensity Distribution (AID) analysis

Measuring stress is critical in the Civil Engineering. However, established acoustic emission-based techniques can hardly evaluate the stress level which a structure is experiencing. Accordingly, an idea of ‘listening’ to Acoustic Emission (AE) to evaluate critical stress states in reinforced concrete (RC) beams is investigated here. Previous work found that the stress diagram of an RC beam cross section strongly correlates with the corresponding AE event intensity distribution pattern. Therefore, the stress level of this type of structures was estimated by utilising the remarkable correlation in this study. First of all, the stress diagrams of a cross section of an RC beam loaded to failure were analysed, revealing features which had close relations with the stress level of the section. Thanks to the correlation, these features were also extracted from the corresponding distribution patterns of the AE event intensity and then used to estimate the stress state. As a result, the AE Intensity Distribution (AID) analysis approach was developed. Data from an experiment conducted on six RC beams with a Digital Image Correlation (DIC) system and an AE device were adopted to verify the approach. Results showed that the indicators of the approach strongly correlated with the stress levels of the specimens; that the approach can characterise the stress states precisely, with an error of about five per cent in critical stages. Besides the approach, more profound significance of this work lies in that it demonstrated the great capability of an innovative strategy, namely characterising structural behaviours accurately via correlating an AE distribution pattern with the corresponding stress diagram.

Near Field Formation via Colloid Particles in Problems of Nanoprocessing Silicon Substrates

A mathematical model for the analysis of the near field intensity distribution in problems of light scattering by particles on the substrate is developed based on the Discrete Sources Method. The influence of the size and material of the particles and the refractive index of the ambient medium on the distribution of the field intensity inside the substrate near the particle is examined.

Classification of Malignancy in Suspicious Lesions Using Autofluorescence Bronchoscopy

This paper presents a novel approach to the classification of bronchial tissue as either malignant or precancerous based on autofluorescence bronchoscopy (AFB) images. The study consisted of 44 images, of which 22 were confirmed as malignant and 22 as nonmalignant precancerous cases. Our approach starts with the detection of a region of interest (ROI). This is followed by an analysis of semi-normal intensity distributions in gray-scale images of red and green components of the previously identified ROI. Based on the results of this analysis, features are computed, which are then used to build an image-classification model. This model classifies the tissue images into malignant/nonmalignant classes. We utilized several classification algorithms, i.e., naive Bayes, K-nearest-neighbor (K-NN), and support vector machine (SVM) with dot kernel. The criteria used when testing their performance were accuracy, sensitivity, specificity, and the area under the curve. Wilcoxon’s signed-rank test was used to confirm the accuracy of the classification method. The proposed method was compared to a similar approach reported by Buountris et al., who analyzed the texture features in a gray-level co-occurrence matrix (GLCM). Using the bestperforming classification algorithm (SVM with dot kernel), the accuracy of the proposed approach (95.8 %) was better than that reported by Bountris et al. (92.1 %).

Analysis of the in-vivo GABAB receptor relocalization and oligomerization in chronic pain conditions using spatial intensity distribution analysis

Abstract The response to the synaptic release of γ-Aminobutyric acid (GABA) in the central nervous system is mediated by the GABAB receptor, inter alia dependent on the formation of receptor oligomers. Spatial intensity distribution analysis (SpIDA) is an image analysis method measuring the oligomerization and density of proteins. It was used to quantify the oligomerization of GABAB receptors in the rodent spinal cord under conditions of chronic pain and inflammation. SpIDA reports a lowered density of tetrameric GABAB receptor entities in GABAergic neurons of the dorsal horn under these conditions compared to sham samples. The soma of neurons in the ventral horn is shown to be populated by single entities of the GABAB receptor. The findings underline the role of receptor oligomerization, as well as the membrane environment in regulating receptor function.

Understanding the photoemission distribution of strongly interacting two-dimensional overlayers

Photoemission tomography (PT), the analysis of the photoemission intensity distribution within the plane wave final-state approximation, is being established as a useful tool for extracting the electronic and geometric structure of weakly interacting organic overlayers. Here we present a simple method for extending PT, which until now has been based on the calculations of isolated molecules. By including the substrate and a damped plane-wave final state, we are able to simulate the photoemission intensity distribution of two-dimensional molecular overlayers with both strong intermolecular and molecule-substrate interactions, here demonstrated for the model system 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) on Cu(100). It is shown that the interaction and hybridization of the lowest unoccupied molecular orbital of PTCDA with substrate states leads to its occupation and the formation of a strongly dispersing intermolecular band, whose experimental magnitude of 1.1 eV and $k$-space periodicity is well reproduced theoretically.

SFIDA: PLATFORM TECHNOLOGY FOR DIAGNOSTICS OF PROTEIN MISFOLDING DISEASES

Protein misfolding is a common hallmark of many neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and prion diseases. Mounting evidence argues that especially smaller aggregates, so called oligomers, are the pathological culprits in these proteinopathies. Therefore the pathological oligomers might be the most direct and reliable biomarker of the respective disorder. To quantify oligomers in body fluids like blood plasma and cerebrospinal fluid (CSF), however, two major technical challenges have to be addressed: i) the extremely low concentration of oligomers and ii) the ubiquitous presence of an excess of monomers. We have developed a method designated sFIDA (surface-based fluorescence intensity distribution analysis) for quantitating single oligomers of amyloid beta, alpha-synuclein and prion protein, respectively. In sFIDA, protein aggregates are fixed on a capture-coated glass surface and loaded with at least two antibodies carrying two different fluorescence dyes. Single protein aggregates are detected by high-resolution imaging like laser scanning and total internal reflection fluorescence microscopy. The use of the same epitope for capturing and probing renders the assay insensitive against monomeric proteins. By sFIDA analysis of CSF samples, a small cohort of AD-affected patients could be distinguished from an age-matched control group. Here we present recent advancements of the sFIDA technology including application of standard molecules for calibration and quantification, assay automatization as well as novel data obtained on patient samples. The sFIDA assay will be employed for biomarker-based monitoring of therapeutic success in drug trials and further adapted for differential diagnostics of other protein misfolding diseases.

Spatial intensity distribution analysis quantifies the extent and regulation of homodimerization of the secretin receptor

Previous studies have indicated that the G-protein-coupled secretin receptor is present as a homodimer, organized through symmetrical contacts in transmembrane domain IV, and that receptor dimerization is critical for high-potency signalling by secretin. However, whether all of the receptor exists in the dimeric form or if this is regulated is unclear. We used measures of quantal brightness of the secretin receptor tagged with monomeric enhanced green fluorescent protein (mEGFP) and spatial intensity distribution analysis to assess this. Calibration using cells expressing plasma membrane-anchored forms of mEGFP initially allowed us to demonstrate that the epidermal growth factor receptor is predominantly monomeric in the absence of ligand and while wild-type receptor was rapidly converted into a dimeric form by ligand, a mutated form of this receptor remained monomeric. Equivalent studies showed that, at moderate expression levels, the secretin receptor exists as a mixture of monomeric and dimeric forms, with little evidence of higher-order complexity. However, sodium butyrate-induced up-regulation of the receptor resulted in a shift from monomeric towards oligomeric organization. In contrast, a form of the secretin receptor containing a pair of mutations on the lipid-facing side of transmembrane domain IV was almost entirely monomeric. Down-regulation of the secretin receptor-interacting G-protein Gαs did not alter receptor organization, indicating that dimerization is defined specifically by direct protein–protein interactions between copies of the receptor polypeptide, while short-term treatment with secretin had no effect on organization of the wild-type receptor but increased the dimeric proportion of the mutated receptor variant.

A Molecular Basis for Selective Antagonist Destabilization of Dopamine D3 Receptor Quaternary Organization

The dopamine D3 receptor (D3R) is a molecular target for both first-generation and several recently-developed antipsychotic agents. Following stable expression of this mEGFP-tagged receptor, Spatial Intensity Distribution Analysis indicated that a substantial proportion of the receptor was present within dimeric/oligomeric complexes and that increased expression levels of the receptor favored a greater dimer to monomer ratio. Addition of the antipsychotics, spiperone or haloperidol, resulted in re-organization of D3R quaternary structure to promote monomerization. This action was dependent on ligand concentration and reversed upon drug washout. By contrast, a number of other antagonists with high affinity at the D3R, did not alter the dimer/monomer ratio. Molecular dynamics simulations following docking of each of the ligands into a model of the D3R derived from the available atomic level structure, and comparisons to the receptor in the absence of ligand, were undertaken. They showed that, in contrast to the other antagonists, spiperone and haloperidol respectively increased the atomic distance between reference α carbon atoms of transmembrane domains IV and V and I and II, both of which provide key interfaces for D3R dimerization. These results offer a molecular explanation for the distinctive ability of spiperone and haloperidol to disrupt D3R dimerization.