Inhomogeneous Patterns Research Articles

Quantification of gastric tube perfusion following esophagectomy using fluorescence imaging with indocyanine green

IntroductionAnastomotic leakage (AL) remains a prevalent and life-threatening complication after esophagectomy. Gastric tube perfusion assessment using indocyanine green fluorescence imaging (ICG-FI) has been published in several studies and appears to be a promising tool to reduce AL rates by changing the surgical approach, namely by an intraoperative evaluation of the anastomosis localization.MethodsIn this study, gastric tube perfusion was quantified by using ICG-FI in 20 high-risk patients undergoing esophagectomy. From a time-dependent fluorescence intensity curve, the following three parameters were evaluated: slope of fluorescence intensity (SFI), background subtracted peak fluorescence intensity (BSFI), and time to slope (TTS).ResultsThe values between pyloric region and tip showed a similar downward trend and SFI and BSFI significantly correlated with the distance to the pyloric region. SFI and BSFI were significantly decreased at the tip of the gastric tube. The placement of anastomosis in an area with homogenous fluorescence pattern was correlated with no AL in 92.9% of cases. An inhomogeneous fluorescence pattern at anastomotic site was a risk factor for the occurrence of an AL (p < 0.05). Reduction of perfusion up to 32% using SFI and up to 23% using BSFI was not associated with AL.ConclusionICG-FI can be used to quantify the gastric tube perfusion by calculating SFI, BSFI, and TTS. The anastomosis should be created in areas with homogeneous fluorescence pattern. A reduction in blood flow of up to 32% can be accepted without causing an increased rate of insufficiency.

Comparison of quasi-geostrophic, hybrid and 3-D models of planetary core convection

SUMMARY We present investigations of rapidly rotating convection in a thick spherical shell geometry relevant to planetary cores, comparing results from quasi-geostrophic (QG), 3-D and hybrid QG-3D models. The 170 reported calculations span Ekman numbers, Ek, between 10−4 and 10−10, Rayleigh numbers, Ra, between 2 and 150 times supercritical and Prandtl numbers, Pr, between 10 and 10−2. The default boundary conditions are no-slip at both the ICB and the CMB for the velocity field, with fixed temperatures at the ICB and the CMB. Cases driven by both homogeneous and inhomogeneous CMB heat flux patterns are also explored, the latter including lateral variations, as measured by Q*, the peak-to-peak amplitude of the pattern divided by its mean, taking values up to 5. The QG model is based on the open-source pizza code. We extend this in a hybrid approach to include the temperature field on a 3-D grid. In general, we find convection is dominated by zonal jets at mid-depths in the shell, with thermal Rossby waves prominent close to the outer boundary when the driving is weaker. For the thick spherical shell geometry studied here the hybrid method is best suited for studying convection at modest forcing, $Ra \le 10 \, Ra_c$ when Pr = 1, and departs from the 3-D model results at higher Ra, displaying systematically lower heat transport characterized by lower Nusselt and Reynolds numbers. We find that the lack of equatorially-antisymmetric motions and z-correlations between temperature and velocity in the buoyancy force contributes to the weaker flows in the hybrid formulation. On the other hand, the QG models yield broadly similar results to the 3-D models, for the specific aspect ratio and range of Rayleigh numbers explored here. We cannot point to major disagreements between these two data sets at Pr ≥ 0.1, with the QG model effectively more strongly driven than the hybrid case due to its cylindrically averaged thermal boundary conditions. When Pr is decreased, the range of agreement between the hybrid and 3-D models expands, for example up to $Ra \le 15 \, Ra_c$ at Pr = 0.1, indicating the hybrid method may be better suited to study convection in the low Pr regime. We thus observe a transition between two regimes: (i) at Pr ≥ 0.1 the QG and 3-D models agree in the studied range of Ra/Rac while the hybrid model fails when $Ra\gt 15\, Ra_c$ and (ii) at Pr = 0.01 the QG and 3-D models disagree for $Ra\gt 10\, Ra_c$ while the hybrid and 3-D models agree fairly well up to $Ra \sim 20\, Ra_c$. Models that include laterally varying heat flux at the outer boundary reproduce regional convection patterns that compare well with those found in similarly forced 3-D models. Previously proposed scaling laws for rapidly rotating convection are tested; our simulations are overall well described by a triple balance between Coriolis, inertia and Archimedean forces with the length-scale of the convection following the diffusion-free Rhines-scaling. The magnitude of Pr affects the number and the size of the jets with larger structures obtained at lower Pr. Higher velocities and lower heat transport are seen on decreasing Pr with the scaling behaviour of the convective velocity displaying a strong dependence on Pr. This study is an intermediate step towards a hybrid model of core convection also including 3-D magnetic effects.

Undifferentiated pleomorphic sarcoma of the pancreas: a rare case report and literature review

BackgroundPrimary undifferentiated pleomorphic sarcoma (UPS) of the pancreas is an exceedingly rare malignant tumor, with only 15 cases have been reported in the medical literature. At present, clinicians have poor recognition of the tumor, the epidemiology, diagnosis, and treatment of this disease have yet not been established.Case presentationIn this report, we depict the clinical and imaging characteristics of a 37-year-old man presenting with a primarily cystic UPS. The patient complained of epigastric pain and distention over 20 days. Abdominal CT and pancreatic magnetic resonance imaging revealed cystic and cystic solid masses in the pancreatic body and tail. An abdominal ultrasound echogram revealed the mass in the body of the pancreas to be cystic with separation echo inside, and the wall was thick, not smooth. Besides, a hypoechoic mass was seen in the tail area of the pancreas with an inhomogeneous echoic pattern, containing small patches of no echo zone in the central. Microscopically, spindle fibroblast-like cells are arranged in a characteristic storiform pattern with pleomorphic and multinucleated cells. Immunohistochemically, tumor cells were positive for CD68 and vimentin. Seven months postoperatively, he was diagnosed with pulmonary lymph node metastasis and died 5 months later. Combined with this case report, we also reviewed the literature regarding UPS of the pancreas.ConclusionsAs we know, this is the first report on ultrasonography findings of pancreatic UPS. Despite there are no distinctive manifestation of UPS, a solid cystic lesion on ultrasonography or a hypodense area in the lesion on T2-weighted imaging, should be considered for differential diagnosis with pancreatic UPS. We believe this article may add some ideas into the diagnosis and therapy of patients with this tumor.

Engineering of properties of low-dimensional materials via inhomogeneous strain

&lt;sec&gt;Low-dimensional material represents a special structure of matter. The exploring of its novel properties is an important frontier subject in the fundamental research of condensed matter physics and material science. Owing to its small length scale in one or two dimensions, low-dimensional materials are usually flexible in structure. This feature together with the prompt electronic response to structural deformations enable us to modulate the material properties via a strain way. The main purpose of this paper is to introduce the recent research progress of obtaining novel physical properties by inhomogeneously straining two-dimensional materials, with focusing on two effects, i.e., pseudomagnetic field effect and the flexoelectric effect. Of course, the influence of inhomogeneous strains on electrons is not limited to these two effects. Fundamentally, an inhomogeneous deformation breaks the symmetry of crystalline structure. This may serve as a start point to delineate the structural-properties relation. First, the symmetry breaking can eliminate the degeneracy of energy levels. Second, the symmetry breaking will also cause the heterogeneity of electronic and phonon properties in different parts of the material.&lt;/sec&gt;&lt;sec&gt;In the paper, we also introduce a special method named the generalized Bloch theorem that is suitable for dealing with the inhomogeneous strain patterns at an atomistic level. From the perspective of atomistic simulation, due to the breaking of translational symmetry, the standard quantum mechanical calculations encounter fundamental difficulties in dealing with an inhomogeneous strain, e.g., bending and torsion. The generalized Bloch method overcomes such an obstacle by considering rotational and/or screw symmetries given by bending and/or torsion in solving the eigenvalue problem. As such, quantum mechanical calculations can be still conducted with a relatively small number of atoms.&lt;/sec&gt;

Turing instability and pattern formations for reaction-diffusion systems on 2D bounded domain

&lt;p style='text-indent:20px;'&gt;In this article, Turing instability and the formations of spatial patterns for a general two-component reaction-diffusion system defined on 2D bounded domain, are investigated. By analyzing characteristic equation at positive constant steady states and further selecting diffusion rate &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ d $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; and diffusion ratio &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$ \varepsilon $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; as bifurcation parameters, sufficient and necessary conditions for the occurrence of Turing instability are established, which is called the first Turing bifurcation curve. Furthermore, parameter regions in which single-mode Turing patterns arise and multiple-mode (or superposition) Turing patterns coexist when bifurcations parameters are chosen, are described. Especially, the boundary of parameter region for the emergence of single-mode Turing patterns, consists of the first and the second Turing bifurcation curves which are given in explicit formulas. Finally, by taking diffusive Schnakenberg system as an example, parameter regions for the emergence of various kinds of spatially inhomogeneous patterns with different spatial frequencies and superposition Turing patterns, are estimated theoretically and shown numerically.&lt;/p&gt;

Nonconstant positive steady states and pattern formation of a diffusive epidemic model

It is our purpose in this paper to make a detailed description for the structure of the set of the nonconstant steady states for the two-dimensional epidemic S-I model with diffusion incorporating demographic and epidemiological processes with zero-flux boundary conditions. We first study the conditions of diffusion-driven instability occurrence, which induces spatial inhomogeneous patterns. The results will extend to the derivative of prey's functional response with prey is positive. Moreover, we establish the local and global structure of nonconstant positive steady state solutions. A priori estimates for steady state solutions will play a key role in the proof. Our results indicate that the diffusion has a great influence on the spread of the epidemic and extend well the finding of spatiotemporal dynamics in the epidemic model.

Sonographic features of lymphoma of the major salivary glands diagnosed with ultrasound-guided core needle biopsy in Sjögren's syndrome.

To identify ultrasound (US) features of lymphomas (L) of major salivary glands (SGs) in primary Sjögren's syndrome (pSS) patients and to differentiate US pattern of L and non-L. Prospectively, from September 2019 to March 2021, 27 pSS-patients with clinical findings suspicious for L of the SGs underwent US evaluation followed by US-guided core-needle biopsy (CNB). For each patient, we assessed the OMERACT score, dichotomised (0/1 "lower", 2/3 "higher"), and we compared it between L-pSS and nonL-pSS groups. For focal lesions, echogenicity, inner appearance, shape, margins, presence of septa, vascularisation and posterior acoustic features were also assessed and compared between the two groups; we planned to consider as "suspicious" features more frequently associated with L. We expected to compare frequencies at which two or more "suspicious" features were simultaneously present between L-pSS and nonL-pSS. P<0.05 were considered statistically significant. L-pSS showed more inhomogeneous glandular pattern (100% vs. 69.2% higher OMERACT; p=0.0407). For focal lesions, the "suspicious" features identified were: OMERACT grade 3, very hypoechoic, homogenous, oval shape, well-defined margins, presence of septa, colour-Doppler vascularization, posterior acoustic enhancement. 6/8 and 7/8 simultaneous suspicious features were significantly higher among L-pSS patients, compared to nonL-pSS (88.9% vs. 28.6%, p=0.034 for 6/8 features; 77.8% vs. 14.3%, p=0.040 for 7/8 features). L of the major SGs in pSS was always associated with OMERACT scores 2 or 3 and presented with diffuse or focal patterns. For focal lesions, the association of more "suspicious" features made the diagnosis of L increasingly more likely. This information can help to improve planning of US-guided CNB.

Data-Driven Retrospective Correction of B1 Field Inhomogeneity in Fast Macromolecular Proton Fraction and R1 Mapping.

Correction of B1 field non-uniformity is critical for many quantitative MRI methods including variable flip angle (VFA) T1 mapping and single-point macromolecular proton fraction (MPF) mapping. The latter method showed promising results as a fast and robust quantitative myelin imaging approach and involves VFA-based R1=1/T1 map reconstruction as an intermediate processing step. The need for B1 correction restricts applications of the above methods, since B1 mapping sequences increase the examination time and are not commonly available in clinics. A new algorithm was developed to enable retrospective data-driven simultaneous B1 correction in VFA R1 and single-point MPF mapping. The principle of the algorithm is based on different mathematical dependences of B1 -related errors in R1 and MPF allowing extraction of a surrogate B1 field map from uncorrected R1 and MPF maps. To validate the method, whole-brain R1 and MPF maps with isotropic 1.25 mm3 resolution were obtained on a 3 T MRI scanner from 11 volunteers. Mean parameter values in segmented brain tissues were compared between three reconstruction options including the absence of correction, actual B1 correction, and surrogate B1 correction. Surrogate B1 maps closely reproduced actual patterns of B1 inhomogeneity. Without correction, B1 non-uniformity caused highly significant biases in R1 and MPF ( ). Surrogate B1 field correction reduced the biases in both R1 and MPF to a non-significant level ( 0.1 ≤ P ≤ 0.8 ). The described algorithm obviates the use of dedicated B1 mapping sequences in fast single-point MPF mapping and provides an alternative solution for correction of B1 non-uniformities in VFA R1 mapping.

Bone metastases with post-treatment intralesional fatty content of the spine: imaging features from T1-weighted imaging with CT finding correlations.

Despite post-treatment intralesional fatty content (PIFAT) in bone metastases indicating a healing processes after treatment, the imaging features of PIFAT have not been studied in detail. To analyze imaging features from T1-weighted (T1W) imaging with computed tomography (CT) finding correlations in bone metastases with PIFAT of the spine. A total of 29 bone metastases with PIFAT were analyzed with T1W and CT images before and after treatment. On T1W imaging after treatment, the lesions were categorized into three types according to fat distribution patterns. CT attenuation changes after treatment were also evaluated. According to the MD Anderson (MDA) criteria, response types for all lesions were obtained on magnetic resonance (MR) and CT images. The types from T1W imaging in bone metastases with PIFAT were as follows: 14 with a return to totally normal marrow signal intensity within the lesion; 13 with an inhomogeneous patchy pattern in the lesion; and two with a peripheral halo of fatty marrow or peripheral fat signal intensity foci in the lesion. Among bone metastases with PIFAT, 93.1% showed osteosclerotic changes in this study. According to the MDA criteria, the concordance between the response types of the MR and CT images was 57.2%. Knowledge of imaging features from T1W imaging with CT correlation in bone metastases with PIFAT is important for the accurate interpretation of post-treatment MR and CT studies. Both MR and CT images have a complementary value regarding the post-treatment evaluation of bone metastases with PIFAT.

Connecting Complex Electronic Pattern Formation to Critical Exponents

Scanning probes reveal complex, inhomogeneous patterns on the surface of many condensed matter systems. In some cases, the patterns form self-similar, fractal geometric clusters. In this paper, we advance the theory of criticality as it pertains to those geometric clusters (defined as connected sets of nearest-neighbor aligned spins) in the context of Ising models. We show how data from surface probes can be used to distinguish whether electronic patterns observed at the surface of a material are confined to the surface, or whether the patterns originate in the bulk. Whereas thermodynamic critical exponents are derived from the behavior of Fortuin–Kasteleyn (FK) clusters, critical exponents can be similarly defined for geometric clusters. We find that these geometric critical exponents are not only distinct numerically from the thermodynamic and uncorrelated percolation exponents, but that they separately satisfy scaling relations at the critical fixed points discussed in the text. We furthermore find that the two-dimensional (2D) cross-sections of geometric clusters in the three-dimensional (3D) Ising model display critical scaling behavior at the bulk phase transition temperature. In particular, we show that when considered on a 2D slice of a 3D system, the pair connectivity function familiar from percolation theory displays more robust critical behavior than the spin-spin correlation function, and we calculate the corresponding critical exponent. We discuss the implications of these two distinct length scales in Ising models. We also calculate the pair connectivity exponent in the clean 2D case. These results extend the theory of geometric criticality in the clean Ising universality classes, and facilitate the broad application of geometric cluster analysis techniques to maximize the information that can be extracted from scanning image probe data in condensed matter systems.

Scalable computational measures for entropic detection of latent relations and their applications to magnetic imaging

Detection of material inhomogeneities is an important task in magnetic imaging and plays a significant role in understanding physical processes. For example, in spintronics, the sample heterogeneity determines the onset of current-driven magnetization motion. While often a significant effort is made in enhancing the resolution of an experimental technique to obtain a deeper insight into the physical properties, here we want to emphasize that an advantageous data analysis has the potential to provide a lot more insight into given data set, in particular when being close to the resolution limit where the noise becomes at least of the same order as the signal. In this work, we introduce two tools - the average latent dimension and average latent entropy - which allow for the detection of very subtle material inhomogeneity patterns in the data. For example, for the Ising model, we show that these tools are able to resolve exchange differences down to $1\%$. For a micromagnetic model, we demonstrate that the latent entropy can be used to detect changes in the easy axis anisotropy from magnetization data. We show that the latent entropy remains robust when imposing noise on the data, changing less than $0.3\%$ after adding Gaussian noise of the same amplitude as the signal. Furthermore, we demonstrate that these data-driven tools can be used to visualize inhomogeneities based on MOKE data of magnetic whirls and thereby can help to explicitly resolve impurities and pinning centers. To evaluate the performance of the average latent dimension and entropy, we show that they outperform common instruments ranging from standard statistics measures to state-of-the-art data analysis techniques such as Gaussian mixture models not only in recognition quality but also in the required computational cost.

Radiation Path of Diurnal Internal Tides in the Northwestern Pacific Controlled by Refraction and Interference

AbstractThe diurnal internal tides contribute nearly a quarter of global baroclinic tidal energy. However, their roles in shaping the spatiotemporal inhomogeneity of the tidal energy field are not well known. Based on observation‐supported numerical simulation and theoretical analyses, we clarify the combined and relative contributions of β refraction, subtidal circulation refraction and multiwave interference to the long‐range radiation and dissipation maps of diurnal internal tides in the northwestern Pacific. The diurnal tidal beams primarily emanate from the Luzon Strait (LS) and Talaud‐Halmahera Passage (THP). The β refraction shifts the mean path of the LS tidal beam equatorward by ∼40° when it arrives at the deep basin. This is consistent with previous altimetric observations. A second refraction effect by subtidal circulation with seasonal variability deflects the mean beam path by ∼10°. Multiwave interference of the tidal beams from the LS and THP further enhances the inhomogeneous pattern. It enhances or reduces the energy fluxes of the tidal beams with distinct vertical structures in the western Mariana basin. A modified line‐source model and theoretical ray‐tracing analysis explain the effects of refraction and interference well. The internal tidal dissipation map in the deep basin coincides well with the inhomogeneous and spreading radiation paths. The characterization of the world's most energetic diurnal internal tides in the northwestern Pacific could improve our understanding of global baroclinic tidal energy redistribution and tidal mixing geography.

Sectoral and growth rate control on elemental uptake by individual calcite crystals

Heterogeneous distribution of trace elements (impurities) within individual calcite crystals is a phenomenon commonly observed in natural and laboratory systems. Changes in thermodynamic intensive parameters (mostly chemical potential and temperature) cannot always explain the inhomogeneous impurity patterns in calcite crystals and it has been suggested that growth rate and crystallographic orientation may exert strong effects on elemental incorporation into calcite. In addition, there are a number of experimental studies on micro-scale element (E) distribution between non-equivalent pairs of calcite vicinal faces (known as sectoral zoning); however, the variability of partition coefficients (e.g., KE = (E/Ca)calcite/(E/Ca)fluid) within individual crystals remains undetermined.In this study, we have extended the work on elemental distribution between crystal sectors to evaluation of partition coefficients of trace and minor elements (Li, B, Mg, and Sr) in calcite crystal faces (10–14) and (01−12), whose growth rates were assessed. Growth entrapment model (GEM) and lattice strain theory were applied to explain KE heterogeneity by varying near-surface diffusivity of Mg and Sr and by varying surface enrichment factor for Li, B, Mg, and Sr. Decoupling of sectoral and growth rate effects reveals that sectoral zoning plays a key role in elemental distribution. More specifically, KLi and KB vary by more than one order of magnitude and KMg varies by a factor of two within individual crystal faces. Strontium sectoral distribution is different from those of Li, B, and Mg and KSr varies by up to a factor of two. These behaviors likely reflect different mechanisms of incorporation of Li, B, Mg, and Sr into calcite.

Spatial movement with diffusion and memory-based self-diffusion and cross-diffusion

Spatial memory has been considered significant in animal movement modeling. In this paper, we formulate a two-species interaction model by incorporating both random walk and spatial memory-based walk in their movement. The spatial memory-based walk, described by a chemotactic-like term, is derived by a modified Fick's law involving a directed movement toward the gradient of the density distribution function at a past time. For the proposed model, local stability and bifurcations are studied at constant steady states. Unlike a classical reaction-diffusion equation, we show that the accumulation points of eigenvalues for the model will locate at a vertical line in the complex plane, which will make the model generate spatially inhomogeneous time-periodic patterns through Hopf bifurcation. As illustrations, we apply these results to competition and cooperative models with memory-based diffusion. For the competition model, it turns out that the outcomes are far more complicated than those of classic Lotka-Volterra reaction-diffusion models, due to the consideration of memory-based diffusion. In particular, the existence of periodic oscillations is proved under weak competition. Similar conclusions hold for the cooperative model.

P36.02 A Case of Recurrent Giant Malignant Solitary Fibrous Tumour of the Pleura: An Elephant in the Room?

Solitary fibrous tumor of the pleura (SFTP) is a rare soft tissue neoplasm, accounting for 4% of chest tumors. The biological behavior of SFTP is generally benign, with 10-15% of SFTP that show malignant features with unpredictable long-term behavior. A 59-year-old Caucasian woman with no history of previous malignancies or comorbidities arrived at our institution with cough, increasing dyspnoea, and chest pain. A chest CT scan showed a giant intra-thoracic mass (25x16x16 cm) partially occupying the right hemithorax (fig.1A). Total body 18F-FDG/PET-CT showed a very inhomogeneous mass pattern, with necrotic areas and areas with various patterns of enhancement. A transthoracic FNAB revealed pulmonary SFTP. After cardio-respiratory complete assessment and tumor board evaluation, the patient underwent surgical excision of the mass en-bloc with right upper lobe by thoracotomy. Microscopically, the tumor showed solid spindle cells with high mitotic activity (5 mitoses/10 HPF), high Ki67 expression, and CD34, bcl2, and STAT6 positive. According to England’s criteria, the diagnosis was indicative of a giant malignant SFTP, and the tumor had a Tapias score of 5, which indicated a high risk of recurrence. The postoperative course was uneventful, and the patient was discharged on 8th postoperative day. Due to R0 resection, no adjuvant radiotherapy or chemotherapy was administered, and a strict follow-up was conducted. After 72 months of follow-up, the patient experimented local pleural recurrences (fig.1B) traded with surgical excision in re-thoracotomy. The histopathological analysis showed eight lesions with a median diameter of 1.5 cm, microscopically composed by spindle cells with 10 mitoses/10 HPF, STAT6+, CD34+. Although R0 resection was achieved, adjuvant chemotherapy was administered. A genome sequencing with the next generation approach was performed on the primary lesion and the recurrent disease. SFTP is a rare neoplasm with unpredictable biological behavior. The surgical resection represents the gold standard if complete resection can be reached. The recently introduced Tapias score can be helpful to assess the risk of recurrence: a strict and long-term follow-up should be conducted in case of a high score (>3). In case of local relapse, surgical excision remains the best therapeutic option.

Logarithmic wave-mechanical effects in polycrystalline metals: theory and experiment

Schrodinger-type wave equations with logarithmic nonlinearity occur in hydrodynamic models of Korteweg-type materials with capillarity and surface tension, which can undergo liquid-solid or liquid-gas phase transitions. One of the predictions of the theory is a periodic pattern of density inhomogeneities occurring in the form of either bubbles (topological phase), or cells (non-topological phase). Such inhomogeneities are described by solitonic solutions of a logarithmic wave equation, gaussons and kinks, in the vicinity of the liquid-solid phase transition. During the solidification process, these inhomogeneities become centers of nucleation, thus shaping the polycrystalline structure of the metal grains. The theory predicts a Gaussian profile of material density inside such a cell, which should manifest in a Gaussian-like profile of microhardness inside a grain. We report experimental evidence of large-scale periodicity in the structure of grains in the ferrite steel S235/A570, copper C-Cu/C14200, austenite in steel X10CrNiTi18-10/AISI 321, and aluminium-magnesium alloy 5083/5056; and also Gaussian-like profiles of microhardness inside an averaged grain in these materials.

Perfusion Patterns of Peripheral Organizing Pneumonia (POP) Using Contrast-Enhanced Ultrasound (CEUS) and Their Correlation with Immunohistochemically Detected Vascularization Patterns.

Purpose: To describe the perfusion patterns of peripheral organizing pneumonia (POP) by contrast-enhanced ultrasound (CEUS) and their correlation with vascularization patterns (VPs) represented by immunohistochemical CD34 endothelial staining. Methods: From October 2006 until December 2020, 38 consecutive patients with histologically confirmed POPs were standardized-examined by CEUS. The time to enhancement (TE; classified as an early pulmonary-arterial [PA] pattern of enhancement vs. delayed bronchial-arterial [BA] pattern of enhancement), the extent of enhancement (EE; classified as marked or reduced), the homogeneity of enhancement (HE; classified as homogeneous or inhomogeneous), and the decrease of enhancement (DE; classified as rapid washout [<120s] or late washout [≥120s]) were evaluated retrospectively. Furthermore, tissue samples from the study patients were immunohistochemically stained with CD34 antibody. The presence of avascular areas (AAs) and the VPs were evaluated in all tissue samples. Results: The majority of POPs showed a BA pattern of enhancement (71.1%), an isoechoic marked enhancement (76.3%), and an inhomogeneous enhancement (81.6%). A rapid DE was observed in 50.0% of cases. On CD34 staining, all POPs had a chaotic VP, indicating BA neoangiogenesis. AAs (abscess, necrosis, hemorrhage) were identified in (41.9%) cases with an inhomogeneous enhancement on CEUS. Conclusion: On CEUS, POPs predominantly revealed a marked inhomogeneous BA pattern of enhancement with a rapid washout in 50% of cases. Furthermore, we demonstrated that the presence of a PA pattern of enhancement, found in 28.9% of POPs, did not exclude a BA neoangiogenesis as an important feature of chronic inflammatory and malignant processes.

Radiative recombination of twisted electrons with hydrogenlike heavy ions: Linear polarization of emitted photons

We present a theoretical investigation of the radiative recombination of twisted Bessel electrons with initially hydrogen-like (finally helium-like) heavy ions. In our study, we focus especially on the linear polarization of x-ray photons emitted in the electron capture into the ground $1{s}_{1/2}^{2}$ ionic state. Particular emphasis is placed on the question of how this polarization is affected if incident hydrogen-like ions are themselves spin-polarized. To explore such a ``polarization transfer'' we apply the density matrix theory and derive the Stokes parameters of recombination x rays for the realistic case of collisions between macroscopic electron and ion beams. Based on the developed general approach two scenarios are discussed that are of interest for the planned experiments at ion storage rings. First, we demonstrate how the use of twisted electrons can empower the known method for the diagnostics of spin-polarized ion beams, based on the rotation of the linear polarization of recombination light. In the second scenario we show how the internal structure of ions beams with inhomogeneous intensity and spin patterns can be probed by the capture of Bessel electrons, carrying different values of angular momentum.

Algorithm for Optimal Two-Link Trajectory Planning in Evasion from Detection Problem of Mobile Vehicle with Non-Uniform Radiation Pattern

The problem of an optimal PP/TP (path/trajectory planning) evasion of a mobile vehicle from the detection is considered. The objective is to minimize the risk of a moving vehicle being detected by a static sensor when moving between two specified points on the plane. Detection is based on the primary acoustic field emitted by a vehicle with an inhomogeneous radiation pattern. An algorithm for finding a two-link optimal trajectory is proposed. The optimal trajectory and the law of speed of a mobile vehicle, as well as the value of the criterion, are found.

Light scattering in TIRF microscopy: A theoretical study of the limits to surface selectivity

In TIRF microscopy, the sample resides near a surface in an evanescent optical field that, ideally, decreases in intensity with distance from the surface in a pure exponential fashion. In practice, multiple surfaces and imperfections in the optical system and refractive index (RI) inhomogeneities in the sample (often living cells) produce propagating scattered light that degrades the exponential purity. RI inhomogeneities cannot easily be avoided. How severe is the consequent optical degradation? Starting from Maxwell’s equations, we derive a first-order perturbative approximation of the electric field strength of light scattered by sample RI inhomogeneities of several types under coherent evanescent field illumination. The approximation provides an expression for the scattering field of any arbitrary RI inhomogeneity pattern. The scattering is not all propagating; some is evanescent and remains near the scattering centers. The results presented here are only a first-order approximation, and they ignore multiple scattering and reflections off the total internal reflection (TIR) surface. For simplicity, we assume that the RI variations in the z direction are insignificant within the depth of the evanescent field and consider only scattering of excitation light, not fluorescence emission light. The general conclusion of most significance from this study is that TIR scattering from a sample with RI variations typical of those on a cell culture alters the effective thickness of the illumination to only ∼50% greater than it would be without scattering. The qualitative surface selectivity of TIR fluorescence is largely retained even in the presence of scattering. Quantitatively, however, scattering will cause a deviation from the incident exponential decay at shorter distances, adding a slower decaying background. Calculations that assume a pure exponential decay will be approximations, and scattering should be taken into account. TIR scattering is only slightly dependent on polarization but is strongly reduced for the highest accessible incidence angles.