Forward Scattering Research Articles

Range-Domain Subspace Detector in the Presence of Direct Blast for Forward Scattering Detection in Shallow-Water Environments

This paper aims to detect a target that crosses the baseline connecting the source and the receiver in shallow-water environments, which is a special scenario for a bistatic sonar system. In such a detection scenario, an intense sound wave, known as the direct blast, propagates directly from the source to the receiver without target scattering. This direct blast usually arrives at the receiver simultaneously with the forward scattering signal and exhibits a larger intensity than the signal, posing a significant challenge for target detection. In this paper, a range-domain subspace is constructed by the horizontal distance between the source/target and each element of a horizontal linear array (HLA) when the ranges of environmental parameters are known a priori. Meanwhile, a range-domain subspace detector based on direct blast suppression (RSD-DS) is proposed for forward scattering detection. The source and the target are located at different positions, so the direct blast and the scattered signal are in different range-domain subspaces. By projecting the received data onto the orthogonal complement subspace of the direct blast subspace, the direct blast can be suppressed and the signal that lies outside the direct blast subspace is used for target detection. The simulation results indicate that the proposed RSD-DS exhibits a performance close to the generalized likelihood ratio detector (GLRD) while requiring less prior knowledge of environments (only known are the ranges of the sediment sound speed and the bottom sound speed), and its robustness to environmental uncertainties is better than that of the latter. Moreover, the proposed RSD-DS exhibits better immunity against the direct blast than the GLRD, since it can still work effectively at a signal-to-direct blast ratio (SDR) of −30 dB, while the GLRD stops working in this case.

Subclonal Populations Detected by Flow Cytometry in Chronic Lymphocytic Leukemia

Abstract Introduction Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is a mature, small B-cell lymphoma that typically co-expresses CD5 and CD23. Molecular-targeted therapies have produced remarkable therapeutic benefits in CLL, yet many patients are resistant to treatment. This study aims to identify subpopulations in CLL by conventional flow cytometry and clustering analysis. Methods One-hundred-and-forty-one CLL cases were taken from a public database and analyzed by uniform manifold approximation and projection (UMAP). Differences in size, granularity, and intensities of CD19, CD20, CD79a, CD5, CD23, CD10, and FMC7 were plotted with BD FACSDiva Software. Eighteen cases with a new diagnosis of CLL at our institution between January 1, 2021 to December 31, 2022 were analyzed. Only peripheral blood samples were included. Markers including forward scatter, side scatter, and fluorescent intensities of CD19, CD20, CD5, CD23, CD10, surface kappa, and surface lambda were used to identify discrete CLL clusters in UMAP plots. Results: Public Dataset Clustering analysis of conventional flow cytometry data from 141 cases from a public database reveals discrete populations of cells exhibiting varying sizes, granularity and fluorescent intensities. Among the 141 cases, 33 (23.4%) had 1 cluster, 64 (45.4%) with 2 clusters, 42 (29.8%) with 3 clusters and 2 (1.4%) with 4 clusters. Among the cases with 2 clusters, a smaller population of cells deviated from the main neoplastic population. This smaller population had a higher forward and side scatter, and brighter intensities in CD45 and CD19, consistent with prolymphocytes. Among the cases with 3 clusters, a third population recurrently had a smaller size by forward scatter. A few cases additionally had varying intensities by CD23 and CD19. Among the 2 cases with 4 clusters, only slight deviations by UMAP were seen and may be artifactual. Institutional Dataset Clustering analysis of 18 cases at our institution revealed complex patterns of cell clusters exhibiting varying sizes, granularity and surface receptor expression intensity. Among the 18 cases, 1 (5.6%) had 1 cluster, 1 (5.6%) with 2 clusters, 10 (55.6%) with 3 clusters, 3 (16.7%) with 4 clusters, and 3 (16.7%) with 5 clusters. Similar to the public dataset, the third population, in addition to the predominant population and prolymphocytes, consistently varied by lower forward scatter. Additional clusters, such as a population with varying CD23 signal intensities, were identified in some cases. Conclusions In our study, multiple clonal subsets in CLL/SLL are detected by conventional flow cytometry analysis. These subclonal populations may result in therapy resistance for these patients, and identifying them by flow cytometry analysis may provide additional prognostic information in the clinical setting. Furthermore, the ability to detect these subclonal populations may allow for isolation of specific clones for future investigation in research settings.

CD5+ Large B cell lymphoma with IRF4 rearrangement: case report and review of the literature

Abstract Introduction/Objective Large B cell lymphoma with IRF4 rearrangement was introduced as a diagnosis by WHO in 2017. It is a rare entity that affects Waldeyer’s ring in mostly males, children and young adults. The lesional immunophenotype may be positive for CD10. FISH is positive for IRF4 rearrangement on chromosome 6p25.Among reported cases in the English literature only 6 cases have reported specifically CD5 being negative. We present review of the literature during years 2020-2024, and a case of large B cell lymphoma with IRF4 rearrangement, specifically positive for CD5. Methods/Case Report The patient is a 5 years old male, since 2017 suffering from recurring ear infections with approximately 4-5 episodes of otitis media during every 6 months. In 2019 the patient’s mother reported snoring, constant sore throat, bad breath for 2 years. On physical examination the left tonsil appeared enlarged; exudative tonsillitis was present. Later on, an asymmetric, firm mass in the location of the left tonsil with induration of the left palate was identified. CT scan showed mild asymmetric soft tissue thickening of the left aspect of the soft palate and left palatine tonsil. Mildly prominent left-sided levels IIa and IIb lymph nodes, measuring up to 1 cm were identified. H&E sections revealed an expansile proliferation of neoplastic cells, large with void to indented nuclei, vesicular chromatin, small nucleoli, visible cytoplasms. Frequent mitoses, apoptosis and individual cell necrosis were seen. Immunohistochemistry revealed CD20+ B cell neoplasm with high expression for MUM1 and high proliferation rate along with strong CD5+ and CD10-. By multicolor flow cytometric studies, an abnormal B cell population was found (40%) with increased forward scatter along with expression for CD5, CD19, CD20, CD22, CD45, CD79a (cytoplasmic), FMC7, (dim) lambda-restriction. Fluorescence In Situ Hybridization Study revealed IRF4 (DUSP22) rearrangement on chromosome 6p25. Results (if a Case Study enter NA) NA Conclusion We analyzed 24 cases reported in the English literature. The mean age of the patients is 7 years old. The majority are males (14/24 = 58%).The most common location is tonsil/ neck mass (15/24 = 62%).CD5 was negative in 6/24 cases.

Serotype 15C Streptococcus pneumoniae resistant to classical complement deposition and agglutination by polyclonal rabbit anti-capsular 15B sera

BackgroundS. pneumoniae (SP) serotypes 15B and 15C are frequent causative agents of invasive pneumococcal disease (IPD), otitis media, and nasopharyngeal colonization in the post PCV13 era. The principal difference between serotypes 15B and 15C is the presence of an O-acetyl group on the pentasaccharide repeating unit of 15B polysaccharide. It remains unclear if antibodies against SP15B polysaccharide demonstrate functional cross reaction with SP15C strains. We compared functional activity of polyclonal rabbit anti-capsular 15B sera against SP15B and SP15C isolates. MethodsUsing flow cytometry we measured complement factors C3c and C4d deposition on SP15B and 15C in the presence of polyclonal rabbit anti capsular 15B sera. We measured the binding of C3c, common to all complement pathways, and C4d, specific to classical pathway, on SP serotypes 15B and 15C when co-incubated with polyclonal rabbit anti capsular 15B sera and antibody depleted complement. Both the proportion of bacteria with complement deposition and the fluorescence intensity were measured. We also measured agglutination as the increase in forward and side scatter. ResultsPolyclonal rabbit anti-capsular 15B sera activated classical pathway resulting in deposition of C4d and C3c at high intensity on all SP15B cells but only achieved limited deposition and intensity of C4 with SP15C. Similarly, polyclonal rabbit anti-capsular 15B sera induced agglutination of SP15B strains in a dose dependent manner and limited agglutination of SP15C. ConclusionsAnti-capsular 15B sera induce limited C4d and C3c deposition, and minimal agglutination with SP15C strains, reflecting lower classical pathway activation in contrast to high C4d and C3c deposition and agglutination of SP15B. These observations support limited functional cross reactivity of anti-15B to SP15C strains and are consistent with the reduction in opsonophagocytic killing of SP15C reported following immunization with vaccines containing 15B polysaccharide.

A-153 Study of the evaluation of fragment flag and percentage schistocyte count in MINDRAY® BC-6800 PLUS in a public pediatric hospital in Argentina

Abstract Background Schistocytes are fragmented red blood cells (FRCs) that arise from the mechanical destruction of red blood cells (RBCs). They indicate the possible presence of a thrombotic microangiopathy (TMA). TMA includes hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura(TTP). ICSH defined schistocytes as 4 well stablish shapes always smaller than intact RBCs. The gold standard for the identification of schistocytes is microscopic evaluation. A schistocyte count should be considered clinically meaningful if it represent the main morphological RBCs abnormality in the periferic blood smear (PBS). The results should be expressed as a percentage, after counting at least 1000 RBCs in optimal areas of the PBS. The cut off for TMA was previously stablished in above 1% (adult population) and a higher percentaje in pre term newborns (above 5%). Some blood cell count analyzers have a flag for FRC, and some of them also provide methods for an automated FRC count, through the measurement of forward scatter and the intensity of fluorescence or 2-dimensional optical analysis. The Mindray® BC 6800 PLUS provides a flag for fragments and the research FRC% parameter that quantifies fragmented RBCs. When the flag and the FRC% are combined, can bring value to diagnostic TMA. Objetives Evaluate the sensitivity and specificity of the fragment flag to predict schistocyte on the PBS of pediatric samples. Evaluate the utility of FRC% as TMA diagnostic tool and compare with the gold standard. Methods 725 pediatric samples were analyzed (0-18 years).16 of them was patient samples diagnosed with TMA. All blood cell counts were determined using Mindray®BC-6800 PLUS. Cut off 1% was considered for FRC% in TMA. Inclusion criteria for TMA samples include thrombocytopenia, increased lactate dehydrogenase and decreased hemoglobin concentration. Schistocyte counting was carried out from May-Grunwald-Giemsa-stained PBS according to the recommendations proposed by ICSH. Only ICSH established shapes were kept as valid. Results Regarding the sensitivity of the fragment flag, it was 84.62% with a specificity of 91.13% to detect the presence of schistocytes in PBS samples. In the Bland-Altman analysis, the FRC% shows a difference with a tendency to underestimation with respect to the observation on the PBS, which was less at lower percentages of schistocytes. The sensitivity of the FRC% to TMA was 75% while the specificity was 94.36% and a negative predictive value (NPV) of 99.41%. Conclusions Fragments flag represents a potentially powerful tool for screening of squistocytes in pediatric samples. Although sensibility and NPV for FRC% authomatical counts were acceptable, a few false-negative samples were found. Presence of FRC% below a threshold of 1% could exclude TMA.However PBS microscopic observation is still the gold standard to determine squistocytes presence. For the purpose of complete our study and to get further larger scale prospective data, we started collecting all data for all samples entering the laboratory in order to improve an authomatical method that should have a more rapid turn-around time at lower costs.

Cell sorting based on pulse shapes from angle resolved detection of scattered light

Flow cytometry is a key technology for the analysis and sorting of cells or particles at high throughput. Conventional and current flow cytometry is primarily based on fluorescent stains to detect the cells of interest. However, such stains also have disadvantages, as their effect on cells must be carefully tested to avoid effects on the results of the experiments. Alternative approaches using imaging or other label-free techniques often require highly sophisticated setups, are commonly limited in resolution, and produce challenging amounts of data. Our technology exploits scattered light instead. The custom-built flow cytometry setup comprises a fiber array in forward scatter detection for angular resolution and captures the whole pulse shape with advanced signal processing. Thereby this setup enables cell analysis and sorting purely based on scattered light signals without the need for fluorescent labels. We demonstrate the feasibility of this cell sorting technology by sorting cell lines for their cell cycle stages based on scattered light. Furthermore, we demonstrate the ability to classify human peripheral blood T- and B-cell subsets.

FAST (fast analytical simulator of tracer)-PET: an accurate and efficient PET analytical simulation tool

Objective. Simulation of positron emission tomography (PET) images is an essential tool in the development and validation of quantitative imaging workflows and advanced image processing pipelines. Existing Monte Carlo or analytical PET simulators often compromise on either efficiency or accuracy. We aim to develop and validate fast analytical simulator of tracer (FAST)-PET, a novel analytical framework, to simulate PET images accurately and efficiently. Approach. FAST-PET simulates PET images by performing precise forward projection, scatter, and random estimation that match the scanner geometry and statistics. Although the same process should be applicable to other scanner models, we focus on the Siemens Biograph Vision-600 in this work. Calibration and validation of FAST-PET were performed through comparison with an experimental scan of a National Electrical Manufacturers Association (NEMA) Image Quality (IQ) phantom. Further validation was conducted between FAST-PET and Geant4 Application for Tomographic Emission (GATE) quantitatively in clinical image simulations in terms of intensity-based and texture-based features and task-based tumor segmentation. Main results. According to the NEMA IQ phantom simulation, FAST-PET’s simulated images exhibited partial volume effects and noise levels comparable to experimental images, with a relative bias of the recovery coefficient RC within 10% for all spheres and a coefficient of variation for the background region within 6% across various acquisition times. FAST-PET generated clinical PET images exhibit high quantitative accuracy and texture comparable to GATE (correlation coefficients of all features over 0.95) but with ∼100-fold lower computation time. The tumor segmentation masks comparison between both methods exhibited significant overlap and shape similarity with high concordance CCC > 0.97 across measures. Significance. FAST-PET generated PET images with high quantitative accuracy comparable to GATE, making it ideal for applications requiring extensive PET image simulations such as virtual imaging trials, and the development and validation of image processing pipelines.

A deep neural network for positioning and inter-crystal scatter identification in multiplexed PET detectors: a simulation study

Objective. High-resolution positron emission tomography (PET) relies on the accurate positioning of annihilation photons impinging the crystal array. However, conventional positioning algorithms in light-sharing PET detectors are often limited due to edge effects and/or the absence of additional information for identifying and correcting scattering within the crystal array (known as inter-crystal scattering). This study explores the feasibility of deep neural network (DNN) techniques for more precise event positioning in finely segmented and highly multiplexed PET detectors with light-sharing. Approach. Initially, a Geant4 Application for Tomographic Emission (GATE) simulation was used to study the spatial and statistical properties of inter-crystal scatter (ICS) events in finely segmented LYSO PET detectors. Next, a DNN for crystal localisation was designed, trained and tested with light distributions of photoelectric (P) and Compton + photoelectric (CP) events simulated using optical GATE and an analytical method to speed up data generation. Using the statistical properties of ICS events, an energy-guided positioning algorithm was then built into the DNN. The positioning algorithm enables selection of the unique or first crystal of interaction in P and CP events, respectively. Performance of the DNN was compared with Anger logic using light distributions from simulated 511 keV point sources placed at different locations around a single PET detector module. Main results. The fraction of events forward and backward scattered in the LYSO detector was 0.54 and 0.46, respectively, whereas naïve application of the Klein–Nishina formulation predicts 70% forward scatter. Despite coarse photodetector data due to signal multiplexing, the DNN demonstrated a crystal classification accuracy of 90% for P events and 82% for CP events. For crystal positioning, the DNN outperformed Anger logic by at least 34% and 14% for P and CP events, respectively. Further improvement is somewhat constrained by the physics—specifically, the ratio of backward to forward scattering of gamma rays within the crystal array being close to 1. This prevents selecting the first crystal of interaction in CP events with a high degree of certainty. Significance. Light sharing and multiplexed PET detectors are common in high-resolution PET, yet their traditional positioning algorithms often underperform due to edge effects and/or the difficulty in correcting ICS events. Our study indicates that DNN-based event positioning has the potential to enhance 2D coincidence event positioning accuracy by nearly a factor of 3 compared to Anger logic. However, further improvements are difficult to foresee without additional information such as event timing.

Prognostic Utility of the Flow Cytometry and Clonality Analysis Results for Feline Lymphomas.

Feline lymphoma, a prevalent cancer in cats, exhibits varied prognoses influenced by anatomical site and cellular characteristics. In this study, we investigated the utility of flow cytometry and clonality analysis via PCR for antigen receptor rearrangement (PARR) with respect to characterizing the disease and predicting prognosis. For this purpose, we received fine needle aspirates and/or blood from 438 feline patients, which were subjected to flow cytometry analysis and PARR. We used a subset of the results from patients with confirmed B- or T-cell lymphomas for comparison to cytological or histological evaluation (n = 53). Using them as a training set, we identified the optimal set of flow cytometry parameters, namely forward scatter thresholds, for cell size categorization by correlating with cytology-defined sizes. Concordance with cytological sizing among this training set was 82%. Furthermore, 90% concordance was observed when the proposed cell sizing was tested on an independent test set (n = 24), underscoring the reliability of the proposed approach. Additionally, lymphoma subtypes defined by flow cytometry and PARR demonstrated significant survival differences, validating the prognostic utility of these methods. The proposed methodology achieves high concordance with cytological evaluations and provides an additional tool for the characterization and management of feline lymphoproliferative diseases.

Ginsenoside Rh2 Regulates the Calcium/ROS/CK1α/MLKL Pathway to Promote Premature Eryptosis and Hemolysis in Red Blood Cells.

Ginsenoside Rh2 (GRh2) exhibits significant potential as an anticancer agent; however, progress in developing chemotherapeutic drugs is impeded by their toxicity toward off-target tissues. Specifically, anemia caused by chemotherapy is a debilitating side effect and can be caused by red blood cell (RBC) hemolysis and eryptosis. Cells were exposed to GRh2 in the antitumor range and hemolytic and eryptotic markers were examined under different experimental conditions using photometric and cytofluorimetric methods. GRh2 caused Ca2+-independent, concentration-responsive hemolysis in addition to disrupted ion trafficking with K+ and Cl- leakage. Significant increases in cells positive for annexin-V-fluorescein isothiocyanate, Fluo4, and 2,7-dichlorofluorescein were noted upon GRh2 treatment coupled with a decrease in forward scatter and acetylcholinesterase activity. Importantly, the cytotoxic effects of GRh2 were mitigated by ascorbic acid and by blocking casein kinase 1α (CK1α) and mixed lineage kinase domain-like (MLKL) signaling. In contrast, Ca2+ omission, inhibition of KCl efflux, and isosmotic sucrose aggravated GRh2-induced RBC death. In whole blood, GRh2 selectively targeted reticulocytes and lymphocytes. Altogether, this study identified novel mechanisms underlying GRh2-induced RBC death involving Ca2+ buildup, loss of membrane phospholipid asymmetry and cellular volume, anticholinesterase activity, and oxidative stress. These findings shed light on the hematologic toxicity of GRh2 which is crucial for optimizing its utilization in cancer treatment.

Multiparameter phenotyping of platelets and characterization of the effects of agonists using machine learning

BackgroundPlatelet function is driven by the expression of specialized surface markers. The concept of distinct circulating subpopulations of platelets has emerged in recent years, but their exact nature remains debatable. ObjectivesTo design a spectral flow cytometry–based phenotyping workflow to provide a more comprehensive characterization, at a global and individual level, of surface markers in resting and activated healthy platelets, and to apply this workflow to investigate how responses differ according to platelet age. MethodsA 14-marker flow cytometry panel was developed and applied to vehicle- or agonist-stimulated platelet-rich plasma and whole blood samples obtained from healthy volunteers, or to platelets sorted according to SYTO-13 (Thermo Fisher Scientific) staining intensity as an indicator of platelet age. Data were analyzed using both user-led and independent approaches incorporating novel machine learning–based algorithms. ResultsThe assay detected differences in marker expression in healthy platelets, at rest and on agonist activation, in both platelet-rich plasma and whole blood samples, that are consistent with the literature. Machine learning identified stimulated populations of platelets with high accuracy (>80%). Similarly, machine learning differentiation between young and old platelet populations achieved 76% accuracy, primarily weighted by forward scatter, cluster of differentiation (CD) 41, side scatter, glycoprotein VI, CD61, and CD42b expression patterns. ConclusionOur approach provides a powerful phenotypic assay coupled with robust bioinformatic and machine learning workflows for deep analysis of platelet subpopulations. Cleavable receptors, glycoprotein VI and CD42b, contribute to defining shared and unique subpopulations. This adoptable, low-volume approach will be valuable in deep characterization of platelets in disease.

Associations Between Visual Functions and Severity Gradings, Corneal Scatter, or Higher-Order Aberrations in Fuchs Endothelial Corneal Dystrophy.

The purpose of this study was to investigate the associations between visual function and severity grading, corneal scatter, or higher-order aberrations (HOAs) in patients with Fuchs endothelial corneal dystrophy (FECD). This observational case series study included 49 eyes of 27 patients with FECD and 10 eyes of 10 healthy individuals. We evaluated corrected distance visual acuity (CDVA) using Landolt-C and Early Treatment Diabetic Retinopathy Study charts and contrast sensitivity using the CSV-1000E chart and CSV-1000RN letter chart. We analyzed the associations between visual function and explanatory variables, including age, modified Krachmer grade, central corneal thickness (CCT), anterior segment optical coherence tomography (AS-OCT)-based grade, HOAs, intraocular straylight, and corneal densitometry. We additionally conducted receiver operating characteristic (ROC) analysis to identify the corneal densitometry thresholds for decreased visual function. There were significant associations between visual function and the modified Krachmer grade, CCT, AS-OCT-based grade, HOAs, intraocular straylight, and corneal densitometry. A modified Krachmer grade ≥ 3 was identified as a threshold for decreased visual function. Multivariate analysis showed that corneal densitometry was significantly associated with all visual function parameters, and HOAs were significantly associated with CDVA but not with contrast sensitivity. ROC analysis revealed that corneal densitometry of the posterior layer at 0 to 2mm ≥ 10 grayscale units (GSU), was identified as a threshold for decreased visual function. HOAs, forward and backward light scatter affected visual function, with backward light scatter being the most influential. In patients with FECD, modified Krachmer grade ≥ 3 and corneal densitometry ≥ 10 GSU were thresholds for visual disturbance.

Applying Nuclear Forward Scattering as In Situ and Operando Tool for the Characterization of FeN4 Moieties in the Hydrogen Evolution Reaction.

Nuclear forward scattering (NFS) is a synchrotron-based technique relying on the recoil-free nuclear resonance effect similar to Mössbauer spectroscopy. In this work, we introduce NFS for in situ and operando measurements during electrocatalytic reactions. The technique enables faster data acquisition and better discrimination of certain iron sites in comparison to Mössbauer spectroscopy. It is directly accessible at various synchrotrons to a broad community of researchers and is applicable to multiple metal isotopes. We demonstrate the power of this technique with the hydrogen evolution mechanism of an immobilized iron porphyrin supported on carbon. Such catalysts are often considered as model systems for iron-nitrogen-carbon (FeNC) catalysts. Using in situ and operando NFS in combination with theoretical predictions of spectroscopic data enables the identification of the intermediate that is formed prior to the rate-determining step. The conclusions on the reaction mechanism can be used for future optimization of immobilized molecular catalysts and metal-nitrogen-carbon (MNC) catalysts.

Forward Light Scattering of the Vitreous Gel After Enzymatic Aging: An In Vitro Model to Study Vitreous Opacification.

Symptomatic vitreous opacifications, so-called floaters, are difficult to objectively assess majorly limiting the possibility of in vitro studies. Forward light scattering was found previously to be increased in eyes with symptomatic floaters. Using an objective setup to measure forward light scattering, we studied the effects of enzymatically digesting the components of the vitreous body on straylight to develop an in vitro model of vitreous opacifications. Fifty-seven porcine vitreous bodies were digested using hyaluronidase, collagenase, trypsin, and bromelain, as well as using a combination of hyaluronidase + collagenase and hyaluronidase + bromelain. A modified C-Quant setup was used to objectively assess forward light scattering. Depletion of hyaluronic acid majorly increased vitreous straylight (mean increase 34.4 deg2/sr; P = 0.01), whereas primarily digesting the vitreous gel with collagenase or trypsin did not significantly affect straylight. When collagenase or bromelain is applied in hyaluronic acid depleted vitreous gels, the increase in forward light scattering is reversed partially. The age-related loss of hyaluronic acid primarily drives the increase in vitreous gel straylight induced by conglomerates of collagen. This process can be reversed partially by digesting collagen. This in vitro model allows the objective quantification and statistical comparison of straylight burden caused by vitreous opacities and, thus, can serve as a first testing ground for pharmacological therapies, as demonstrated with bromelain.

Rao and Wald Tests for Moving Target Detection in Forward Scatter Radar

This paper deals with adaptive moving target detection for a forward scatter radar in complex Gaussian noise. The echoes received by the forward scatter radar include not only the noise and the possible target signals but also the direct signals. To suppress the direct signals and detect the target signals, Rao and Wald tests are derived in two cases: the secondary data which contain no target signal are available or not available. Different from monostatic radar, it is proved that the derived Rao and Wald detectors for the forward scatter radar have the same test statistics as the generalized likelihood ratio test-based detector in the complex Gaussian noise both when the secondary data are available or not available. The numerical evaluation further demonstrates the equivalence and the effectiveness of the proposed detectors.

A Heuristic Forward Scatter Radar Detector for Sky Fence With Opportunistic Signals From LEO Satellites

A Heuristic Forward Scatter Radar Detector for Sky Fence With Opportunistic Signals From LEO Satellites

An Efficient Multiple Scattering Solution to Radiative Transfer Equations in Strong Forward Scattering Environments for Vegetated Land Emission and its Representation Through an Equivalent Albedo-Tau Formalism

An Efficient Multiple Scattering Solution to Radiative Transfer Equations in Strong Forward Scattering Environments for Vegetated Land Emission and its Representation Through an Equivalent Albedo-Tau Formalism

CD49f and CD146: A Possible Crosstalk Modulates Adipogenic Differentiation Potential of Mesenchymal Stem Cells.

The lack of appropriate mesenchymal stem cells (MSCs) selection methods has given the challenges for standardized harvesting, processing, and phenotyping procedures of MSCs. Genetic engineering coupled with high-throughput proteomic studies of MSC surface markers arises as a promising strategy to identify stem cell-specific markers. However, the technical limitations are the key factors making it less suitable to provide an appropriate starting material for the screening platform. A more accurate, easily accessible approach is required to solve the issues. This study established a high-throughput screening strategy with forward versus side scatter gating to identify the adipogenesis-associated markers of bone marrow-derived MSCs (BMSCs) and tonsil-derived MSCs (TMSCs). We classified the MSC-derived adipogenic differentiated cells into two clusters: lipid-rich cells as side scatter (SSC)-high population and lipid-poor cells as SSC-low population. By screening the expression of 242 cell surface proteins, we identified the surface markers which exclusively found in lipid-rich subpopulation as the specific markers for BMSCs and TMSCs. High-throughput screening of the expression of 242 cell surface proteins indicated that CD49f and CD146 were specific for BMSCs and TMSCs. Subsequent immunostaining confirmed the consistent specific expression of CD49f and CD146 and in BMSCs and TMSCs. Enrichment of MSCs by CD49f and CD146 surface markers demonstrated that the simultaneous expression of CD49f and CD146 is required for adipogenesis and osteogenesis of mesenchymal stem cells. Furthermore, the fate decision of MSCs from different sources is regulated by distinct responses of cells to differentiation stimulations despite sharing a common CD49f+CD146+ immunophenotype. We established an accurate, robust, transgene-free method for screening adipogenesis associated cell surface proteins. This provided a valuable tool to investigate MSC-specific markers. Additionally, we showed a possible crosstalk between CD49f and CD146 modulates the adipogenesis of MSCs.

A Flow Cytometry Study of the Binding and Stimulation Potential of Inactivated Trypanosoma evansi toward Dromedary Camel Leukocytes.

Surra, a wasting disease caused by Trypanosoma evansi, is one of the major animal health burdens in camel-rearing countries, imposing significant economic losses due to reduced fertility and high mortality rates. The present study used inactivated T. evansi (from the Card Agglutination Test for Trypanosomes/Trypanosoma evansi; CATT/T. evansi) and flow cytometry to investigate their binding and activation potential toward camel leukocyte subsets. Labeling T. evansi with propidium iodide (PI) enabled their flow cytometric enumeration and identification with forward scatter (FSC; indicative for cell size) and side scatter (SSC; indicative for cell internal complexity) characteristics that are comparable with values reported for Trypanosoma cruzi. The incubation of PI-labeled non-opsonized T. evansi with camel leukocyte populations revealed that camel monocytes have the highest potential to bind T. evansi, followed by granulocytes and lymphocytes. The identification of pattern recognition receptors (PRRs) on camel immune cells and the pathogen-associated molecular patterns (PAMPs) in T. evansi that are responsible for this different binding capacity requires further studies. Stimulation of camel neutrophils with Trypanosoma evansi induced shape change, reactive oxygen species (ROS) production, and neutrophil extracellular traps (NET)-formation. To ensure that T. evansi, in the parasite concentration used in this study, is not apoptotic or necrotic to camel leukocytes, we evaluated cell apoptosis and necrosis after stimulation with T. evansi. The results revealed no impact of T. evansi stimulation for 2 h on the cell viability of camel leukocytes. Subsequent work may focus on the diagnostic employment of labeled T. evansi and flow cytometry for the detection of anti-Trypanosoma antibodies in camel serum. In addition, more efforts should be deployed to investigate the host-pathogen interaction mechanisms and the escape mechanisms of T. evansi in camels. To complete these data, further studies using the living or freshly killed parasites could also be implemented in camels and/or horses.

Fluorescent characterization of differentiated myotubes using flow cytometry.

Flow cytometry is routinely used in the assessment of skeletal muscle progenitor cell (myoblast) populations. However, a full gating strategy, inclusive of difficult to interpret forward and side scatter data, which documents cytometric analysis of differentiated myoblasts (myotubes) has not been reported. Beyond changes in size and shape, there are substantial metabolic and protein changes in myotubes allowing for their potential identification within heterogenous cell suspensions. To establish the utility of flow cytometry for determination of myoblasts and myotubes, C2C12 murine cell populations were assessed for cell morphology and metabolic reprogramming. Laser scatter, both forward (FSC; size) and side (SSC; granularity), measured cell morphology, while mitochondrial mass, reactive oxygen species (ROS) generation and DNA content were quantified using the fluorescent probes, MitoTracker green, CM-H2DCFDA and Vybrant DyeCycle, respectively. Immunophenotyping for myosin heavy chain (MyHC) was utilized to confirm myotube differentiation. Cellular viability was determined using Annexin V/propidium iodide dual labelling. Fluorescent microscopy was employed to visualize fluorescence and morphology. Myotube and myoblast populations were resolvable through non-intuitive interpretation of laser scatter-based morphology assessment and mitochondrial mass and activity assessment. Myotubes appeared to have similar sizes to the myoblasts based on laser scatter but exhibited greater mitochondrial mass (159%, p < 0.0001), ROS production (303%, p < 0.0001), DNA content (18%, p < 0.001) and expression of MyHC (147%, p < 0.001) compared to myoblasts. Myotube sub-populations contained a larger viable cluster of cells which were unable to be fractionated from myoblast populations and a smaller population cluster which likely contains apoptotic bodies. Imaging of differentiated myoblasts that had transited through the flow cytometer revealed the presence of intact, 'rolled-up' myotubes, which would alter laser scatter properties and potential transit through the laser beam. Our results indicate that myotubes can be analyzed successfully using flow cytometry. Increased mitochondrial mass, ROS and DNA content are key features that correlate with MyHC expression but due to myotubes 'rolling up' during flow cytometric analysis, laser scatter determination of size is not positively correlated; a phenomenon observed with some size determination particles and related to surface properties of said particles. We also note a greater heterogeneity of myotubes compared to myoblasts as evidenced by the 2 distinct sub-populations. We suggest that acoustic focussing may prove effective in identifying myotube sub populations compared to traditional hydrodynamic focussing.