Sinusoidal Density Research Articles

Effects of combined growth hormone and testosterone treatments in a rat model of micropenis.

Although it is well known that penile growth is dependent on androgens, few clinical studies have reported successful treatment of micropenis with testosterone, likely due to concerns regarding the efficacy and safety of prolonged testosterone use. Thus, we assessed the synergenic effects of growth hormone (GH) treatments with and without testosterone on phallic growth in a rat model of micropenis. Fifty Sprague–Dawley rats were assigned to control (C), microphallus (MP), testosterone, GH (G) and GH plus testosterone (GT) treatment groups, and microphallus was induced by secondary hypogonadism. Pre-pubertal treatments with testosterone, GH or the combination were initiated from 7 days after birth and were maintained until 12 weeks of age. To assess the efficacy of treatments, phallic dimensions were determined and histological markers of cavernosal integrity were evaluated. Skeletal and gonadal safety profiles of the treatments were then assessed according to right tibial lengths and testicular weights, respectively. No monotreatments normalised penile dimensions, whereas combination treatments led to complete restoration. The combination treatment also prevented decreases in histological indicators of cavernosal integrity, including smooth muscle actin and collagen III expression levels and fat globule accumulation and sinusoidal density. These synergenic effects of GH treatments on penile growth may follow changes in androgen receptor expression levels and were accompanied by decreased testicular volume losses. Although the physiological conditions of phallic growth differ between humans and rats, this proof-of-concept study provides a strategy for circumventing the problems of testosterone monotherapy for human micropenis.

Влияние мелатонина на клеточный состав печени крыс Wistar при алиментарном ожирении

Цель - морфофункциональная характеристика нарушений функции печени при алиментарном ожирении и их коррекция мелатонином. Методы. В эксперименте использовано 3 группы половозрелых (2 мес.) крыс-самок Wistar с исходной массой 180-200 г. 1-я группа - контроль (интактные крысы); 2-я - группа «ожирение» (модель алиментарного ожирения воспроизводилась путем добавления (без ограничения) к стандартному лабораторному рациону в течение 3 мес. пищевых жиров животного происхождения) и 3-я группа («ожирение + мелатонин») - животные с алиментарным ожирением, которым в течение 14 сут. per os через желудочный зонд 1 раз в сут. вводили водный раствор мелатонина (0,1 г на 100 г массы тела), животные жиры из рациона во время введения препарата не исключались. Крыс декапитировали под этаминаловым наркозом (40 мг на кг), извлекали печень для морфометрического и светооптического исследования (микроскоп LEICA DM 750, камера LEICA ICC 50 HD). Патогистологические препараты готовили по общепринятой методике. Исследование препаратов печени проводили при увеличении х1000 на срезах толщиной 5 мкм, окрашенных гематоксилином Майера и эозином, сульфатом нильского голубого. Для морфометрического анализа использовали метод наложения точечных морфометрических сеток (сетка 256 точек). Определяли относительную площадь сети синусоидов, ядер и цитоплазмы гепатоцитов, численную плотность синусоидных клеток и гепатоцитов и двуядерных паренхиматозных клеток; рассчитывали ядерно-цитоплазматическое соотношение, отношение численной плотности синусоидных клеток к численной плотности всех гепатоцитов, вычисляли долю диплокариоцитов от общего числа гепатоцитов, рассчитывали коэффициент Vizotto - отношение площади сети синусоидов к площади всех гепатоцитов. Результаты. Введение мелатонина нивелировало признаки нарушения кровообращения, крово- и лимфотока. Отмечалась сохранность сосудов портального тракта, восстановление архитектоники центральных вен. Большинство участков гемо- и лимфообращения не имело признаков грубых нарушений. Заключение. Ожирение приводит к значительным нарушениям в системе кровообращения и лимфотока в печени, развитию жировой дистрофии. Введение таким животным гормона эпифиза мелатонина способствует усилению репаративных процессов в печени, нормализации микроциркуляторных процессов, восстановлению микроструктурной и функциональной организации органа.Aim. To identify and assess morpho-functional changes in the liver of Wistar rats on a model of alimentary obesity and correct the changes with the pineal hormone, melatonin, a universal adaptogen, immune modulator, and potent antioxidant. Methods. Sexually mature female Wistar rats aged 2 months and weighing 180-200 g at baseline were used for the experiment. Rats were allocated to three groups, 1) control group (intact rats); 2) group with alimentary obesity modeled by adding animal fat to the ad libitum standard laboratory diet for 3 months (obesity group); and 3) obesity group treated with melatonin 0.1 g/100 g body weight in 200 µl of distilled water, orally through a gastric tube, once daily for 14 days; during the treatment, animal fat was not excluded from the diet (obesity + melatonin group). Rats were sacrificed under etaminal anesthesia (40 mg/kg body weight) by decapitation. For morphometric and optical studies (LEICA DM 750 microscope, LEICA ICC 50 HD camera), histopathological preparations were fixed in 10% buffered formalin and examined with a standard method. Morphometric studies of liver samples were performed at a x1000 magnification on 5 µm sections stained with Mayer’s hematoxylin and eosin stain and Nile blue sulfate using superposition of point morphometric grids (grid of 256 points). Relative areas of sinusoid network, hepatocyte nuclei and cytoplasm; numerical density of sinusoidal cells, hepatocytes, and dual-parenchymal cells were measured. The nuclear-cytoplasmic ratio; ratio of sinusoidal cell numerical density to the numerical density of all hepatocytes; and per cent of diplocaryocytes of the total number of hepatocytes were computed; the Vizotto coefficient was calculated as a ratio of the area of sinusoid network to the area of all parenchymal hepatocytes. Results. Administration of the animal hormone, melatonin, exerted a pronounced effect on the studied morphometric parameters and reversed signs of circulatory and lymph flow disorders. Blood vessels of the portal area were preserved, and the architectonics of central veins was recovered. Most parts of hemo- and lymph circulation had no abnormal features. Conclusion. Obesity leads to significant disorders of blood circulation and lymph flow in the liver and results in fatty degeneration of hepatic parenchyma. Administration of the pineal hormone, melatonin, to such animals enhances reparative processes in the liver, normalizes microcirculation, and restores the structural and functional organization of the body.

Microcirculatory disturbances and cellular changes during progression of hepatic steatosis to liver tumors.

Non-alcoholic fatty liver disease is closely associated with metabolic syndrome and comprises a pathological spectrum of liver disease ranging from steatosis to steatohepatitis and can progress to fibrosis/cirrhosis and hepatocellular carcinoma. In 2013, a mouse model was described that mimics non-alcoholic fatty liver disease progression from steatohepatitis to tumors in a short time span and with high incidence. As microcirculatory disturbances play a crucial role in liver disease, the suitability of the steatosis-inflammation-tumor model for microcirculatory studies was assessed. Herein, we present a comprehensive view on morphological, microvascular, cellular, and functional aspects of non-alcoholic fatty liver disease progression in the steatosis-inflammation-tumor model using intravital microscopy, biochemical, and histological techniques. Mice develop steatohepatitis, mild fibrosis, and liver tumors at ages of 6, 12, and 20 weeks, respectively. Non-alcoholic fatty liver disease progression was accompanied by several general aspects of disease severity like increasing liver/body weight index, non-alcoholic fatty liver disease activity score, and hepatocellular apoptosis. Intravital microscopic analysis revealed significant changes in hepatic microcirculation with increasing structural alterations, elevated leukocyte adherence, and impaired nutritive perfusion. Non-alcoholic fatty liver disease was further characterized by a lower sinusoidal density with a striking rise at 20 weeks. The characteristic microcirculatory changes make the model a convenient tool for analysis of microcirculation during progression from steatosis to liver tumor. Impact statement Significant alterations of microcirculation contribute to progression of NAFLD, a chronic liver disease with increasing medical and socio-economic impact. Characterization of microcirculation in a NAFLD model reflecting all relevant stages of disease progression was still missing. Thus, we evaluated microcirculatory and cellular changes in a steatosis-inflammation-tumor model using in vivo microscopy. Analyses revealed increasing structural alterations, elevated leukocyte-endothelial interaction, and impaired nutritive perfusion. Thus, this model is suitable for further studies investigating therapeutic approaches targeting these progressive microcirculatory disturbances.

Transition of backward stimulated Raman scattering from absolute to convective instability via density modulation

The effect of a static sinusoidal density modulation on the temporal growth rate of backward stimulated Raman scattering (BSRS) is discussed by kinetic theory and Vlasov simulation. One-dimensional Vlasov simulations show that the temporal growth rate will decrease with the increasing density modulation amplitude ε, which is consistent with the kinetic theory. Moreover, the transition from an absolute instability to a convective instability via the density modulation is also observed from the variation of the temporal growth rate of BSRS. The temporal growth rate in the case of density modulation wave-number ks=0.1kl (kl is wave-number of Langmuir wave) decreases faster with increasing ε than that in the case of ks=0.5kl because of the generation of more modes, which will make Landau damping of Langmuir waves stronger. In addition to the generation of other modes, the decrease of the resonant region where BSRS occurs with the increasing density modulation amplitude ε is also a reason for the reduction of the temporal growth rate.

Dynamic Design of Spatial Patterns of Colloidal Suspensions.

We study the collective dynamics of colloidal suspensions in the presence of a time-dependent potential by means of dynamic density functional theory. We consider a nonlinear diffusion equation for the density and show that spatial patterns emerge from a sinusoidal external potential with a time-dependent wavelength. These patterns are characterized by a sinusoidal density with the average wavelength and a Bessel-function envelope with an induced wavelength that depends only on the amplitude of the temporal oscillations. As a generalization of this result, we propose a design strategy to obtain a family of spatial patterns using time-dependent potentials of practically arbitrary shape.

Line start permanent magnet motors with double‐barrier configuration for magnet conservation and performance improvement

This study proposes a new configuration for line start permanent magnet (PM) motors with low consumption of PM material, providing improved performance. The configuration is developed by analysing PM flux density distribution in the machine airgap and focusing on the d-axis armature reaction flux path and also different magnetisation types in the PM poles. It features double flux barriers for each rotor pole to facilitate near sinusoidal flux density distribution. Main characteristics of a motor with the proposed configuration are analysed by finite element method (FEM) and compared with the characteristics of a motor with the conventional configuration. Finally, the motor is built and tested. The FEM and experimental results verify the advantages of the proposed configuration. The results show that the required PM material reduces by one-third, while desirable performance is provided. The machine is capable of working with delta connection causing negligible circulating current and low torque ripples.

A high-order nodal discontinuous Galerkin method for solution of compressible non-cavitating and cavitating flows

In this work, a high-order nodal discontinuous Galerkin method is applied and assessed for the simulation of compressible non-cavitating and cavitating flows. The one-fluid approach with the thermal effects is used to properly model the cavitation phenomenon. Here, the spatial and temporal derivatives in the system of governing equations are discretized using the nodal discontinuous Galerkin method and the third-order TVD Runge–Kutta method, respectively. Various numerical fluxes such as the Roe, Rusanov, HLL, HLLC and AUSM+-up and two discontinuity capturing methods, namely, the generalized MUSCL limiter and a generalized exponential filter are implemented in the solution algorithm. At first, the sinusoidal density wave problem which has a smooth solution is simulated and the effects of the numerical fluxes on the accuracy and performance of the nodal discontinuous Galerkin method are studied. Two problems, namely, the shock–density interaction (non-cavitating flow) and the two symmetric expansion waves (cavitating flow) are then computed and the effects of the numerical fluxes and the discontinuity capturing methods on the accuracy and computational cost of the solution are investigated. For non-cavitating flows, the high-pressure water–water shock tube and the low-pressure water–water shock tube are also simulated. Then, three cavitating flow problems, namely, the two symmetric expansion waves, the shock-condensation tube and the collapsing cavitation bubble are simulated to assess the accuracy and robustness of the solution algorithm. Results show that the solution methodology based on the high-order NDGM is accurate and robust for simulating the compressible non-cavitating and cavitating flows.

Density modulation-induced absolute laser-plasma-instabilities: Simulations and theory

Fluid simulations show that when a sinusoidal density modulation is superimposed on a linear density profile, convective instabilities can become absolutely unstable. This conversion can occur for two-plasmon-decay and stimulated Raman Scattering instabilities under realistic direct-drive inertial confinement fusion conditions and can affect hot electron generation and laser energy deposition. Analysis of the three-wave model shows that a sufficiently large change of the density gradient in a linear density profile can turn convective instabilities into absolute ones. An analytical expression is given for the threshold of the gradient change for a two-slope density profile, which depends on the convective gain only.

Shear banding in metallic glasses described by alignments of Eshelby quadrupoles

Plastic deformation of metallic glasses performed well below the glass transition temperature leads to the formation of shear bands as a result of shear localization. It is believed that shear banding originates from individual stress concentrators having quadrupolar symmetry. To elucidate the underlying mechanisms of shear band formation, microstructural investigations were carried out on sheared zones using transmission electron microscopy. Here we show evidence of a characteristic signature present in shear bands manifested in the form of sinusoidal density variations. We present an analytical solution for the observed post-deformation state derived from continuum mechanics using an alignment of quadrupolar stress field perturbations for the plastic events. Since we observe qualitatively similar features for three different types of metallic glasses that span the entire range of characteristic properties of metallic glasses, we conclude that the reported deformation behavior is generic for all metallic glasses, and thus has far-reaching consequences for the deformation behavior of amorphous solids in general.

Numerical study on free convection of cold water in a square porous cavity heated with sinusoidal wall temperature

PurposeThe aim of the present study is to analyze the natural convection flow and heat transfer of cold water around °C in a square porous cavity. The horizontal walls of cavity are adiabatic, and the vertical walls are maintained at different temperatures. The right side wall is maintained at temperature θc, and the left side wall is maintained at sinusoidal temperature distribution.Design/methodology/approachThe Brinkman–Forchheimer-extended Darcy model for porous medium is used to study the effects of density inversion parameter, Rayleigh number and impact of Darcy number and porosity. The finite volume method is used to solve the governing equations.FindingsThe heat transfer rate is increased on increasing the Darcy number and porosity. Also, the convective heat transfer rate is decreased first and then increased on increasing the density inversion parameter.Research limitations/implicationsThe numerical computations have been carried out for the Darcy number ranging of 10(−4) ≤ Da ≤ 10(−1), the porosity ranging of 0.4 ≤ ε ≤ 0.8 and the density inversion parameter ranging of 0 ≤ Tm ≤ 1 and keeping Ra = 106.Practical implicationsThe results can be used in the cooling of electronic components, thermal storage system and in heat exchangers.Originality/valueThe choice of consideration of sinusoidal heating and density maximum effect produces good result in flow field and temperature distribution. The obtained results can be used in various fields.

Postreperfusion microcirculatory derangements after liver transplantation: Relationship to hemodynamics, serum mediators, and outcome.

Despite the growing data supporting the role of microcirculation in regulating liver function, little of this knowledge has been translated into clinical practice. The aim of this study is to quantify hepatic microcirculation in vivo using sidestream dark field (SDF) imaging and correlate these findings with hepatic blood flow, hemodynamic parameters, and soluble mediators. Postreperfusion hepatic microcirculation was assessed using SDF imaging. Hepatic microcirculation measurements included functional sinusoidal density (cm/cm2 ), sinusoidal diameter (μm), red blood cell velocity (μm/second), volumetric blood flow (pl/second), and flow heterogeneity (FH) index. The serum concentrations of endothelin 1 (ET-1) and other inflammatory markers were analyzed with Luminex technology. Portal venous and hepatic artery flows were measured using a flowmeter. Twenty-eight patients undergoing cadaveric liver transplantations have been included in this study. Early allograft dysfunction (EAD) occurred in 7 (25%) patients and was associated with microcirculatory dysfunction. Low arterial and portal flow, high dose of inotropes, cold ischemia time, steatosis, and high ET-1 levels were all associated with impaired microcirculation. The time interval between portal venous and hepatic arterial reperfusion significantly correlated with the changes of the liver grafts' microcirculation. EAD patients tended to have higher serum levels of ET-1 on postoperative days 1, 2, 5, and 7 (all P < 0.01). Serum levels of ET-1 correlated significantly with microcirculation parameters. In conclusion, postreperfusion hepatic microcirculation is a determinant of organ dysfunction after liver reperfusion and could be used to identify very early patients at risk of EAD. Liver Transplantation 23 527-536 2017 AASLD.

Effect of density modulation on backward stimulated Raman Scattering in a laser-irradiated plasma

The influence of an arbitrary static sinusoidal density modulation on Raman backscattering is discussed theoretically and numerically. One-dimensional Vlasov simulations show a suppression of convective gain of seed with large modulation amplitude ϵ or small modulation vector ks, which is consistent with the modulation theory, namely, the generation of harmonics. However, this initial suppression is soon replaced by a periodic enhancement of reflectivity in the nonlinear stage due to the different performance of Langmuir wave propagation in density peaks and valleys. Modulation effects are also instantiated in electron acceleration. With large ks, finite orders of harmonics may lead to obvious layers of the phase island structure, and local phase island mixing occurs when the wave amplitude increases. With small ks, electrons could be accelerated by a series of adjacent harmonics from low phase velocity to high phase velocity step by step, which may produce a large number of superthermal electrons even with relativistic kinetic energy.

Bone Marrow Remodelling and Topographic Redistribution of CD34 Positive Progenitors Characterize the Progression of Myelodysplastic Syndromes and Their Evolution to AML

Myelodysplastic Syndrome (MDS) is a multifaceted disease of Hematopoietic Stem Cells characterized by myeloproliferation associated with mono- or pan-cytopenia, ultimately leading to an advantageous clonal growth of frankly leukemic cells. Although the disruption of bone marrow (BM) architecture and alterations of differentiated hematopoietic compartments have been repeatedly described, the potential involvement of the structural remodeling and redistribution of hematopoietic progenitors within the BM on the evolution of MDS has been poorly investigated. The aim of our study was to determine whether the number and localization of CD34pos progenitors and vascular structures are differentially affected in MDS subcategories and whether these changes are associated with disease progression. Thus, the morphometric evaluation of the number and linear distance from the endosteal surface (PT: paratrabecular <20mm; IT: intertrabecular >21mm) of capillaries, sinusoids, arterioles and CD34pos progenitors was performed by immunohistochemistry on BM biopsies from 97 consecutive MDS patients (12 RA; 2 RCUD; 19 RCMD; 3 RARS-T; 2 5q-; 20 RAEB-1; 27 RAEB-2; 12 U-MDS) in stable or evolving disease and in 15 cases that progressed to AML. Controls (CTR) were represented by 22 disease-free BM biopsies. Risk stratification was based on IPSS. Compared to CTR, capillary density linearly increased in IT marrow from RA thorough RAEB-1, with a subsequent progressive drop in RAEB-2 and AML. Sinusoid density was reduced in MDS and progressively declined from RAEB-1 through AML. PT and IT arterioles increased by more than 3-fold in MDS vs CTR although a progressive rarefaction associated with an increased thickness was measured from RA thorough RAEB-2. A marked rise in arteriolar number was also observed in AML. As expected, CD34pos cell number progressively increased with the severity of the disease, however, a sharp redistribution from PT to perisinusoid and fat areas within the IT marrow was documented (Figure). Intriguingly, the BM redistribution of vascular structures had higher impact than the increased number of CD34pos progenitors to identify high risk MDS and the subset of MDS patients who subsequently developed AML. Finally, patients responsive to azacytidine displayed a reduced number and a topographic redistribution of CD34pos cells together with an increased BM capillarization. BM structural remodelling and rearrangement of hematopoietic progenitors characterize the evolution of MDS. The prognostic significance and the predictive value of these parameters may be translated in new therapeutic approaches able to improve patient management. [Display omitted] DisclosuresGiuliani:Janssen: Research Funding; Celgene: Research Funding.

Delayed liver regeneration in C3H/HeJ mice: possible involvement of haemodynamic and structural changes in the hepatic microcirculation

What is the central question of this study? The liver regenerative process is complex and involves a sequence of signalling events, but the possible involvement of structural and haemodynamic changes in vivo during this process has never been explored. What is the main finding and its importance? Normal sinusoidal blood flow and velocity are crucial for a normal regenerative response, and delays in these haemodynamic events resulted in impaired liver regeneration in lipopolysaccharide-insensitive, C3H/HeJ mice. Toll-like receptor 4 signalling is required for restoration of normal liver architecture during the liver regenerative process. Liver regeneration is delayed in mice with a defective Toll-like receptor 4 (TLR4; C3H/HeJ mice) but is normal in TLR4 knockouts (TLR4-/- ). Here, we investigated the possible involvement of structural and haemodynamic changes in vivo in the underlying mechanism. In lipopolysaccharide-sensitive (C3H/HeN and C57BL/6) and lipopolysaccharide-insensitive (C3H/HeJ and TLR4-/- ) mice, a 70% partial hepatectomy (PH) was performed under inhalational anaesthesia. At days 3 and 7 after PH, the hepatic microcirculation was interrogated using intravital microscopy. Delayed liver regeneration was confirmed in C3H/HeJ, but not in C3H/HeN, C57BL/6 (WT) or TLR4-/- mice by liver weight-to-body-weight ratio, the percentage of proliferating cell nuclear antigen (PCNA)-positive cells and mitotic index data. At day 3 after PH, sinusoidal red blood cell velocity increased by 100% in C3H/HeN mice, but by only 40% in C3H/HeJ mice. Estimated sinusoidal blood flow was significantly higher at day 7 after PH in C3H/HeN than in C3H/HeJ mice. The hepatic cord width was significantly larger in C3H/HeN than in C3H/HeJ mice at day 3 and it was significantly larger in TLR4-/- than in C57BL/6 WT mice at day 7 after PH. Hepatocyte nucleus density and functional sinusoidal density was significantly reduced at days 3 and 7 after PH in all mouse strains compared with their zero-time controls. Functional sinusoidal density was significantly lower in C3H/HeJ compared with C3H/HeN mice at day 7 after PH. The present study indicates that altered sinusoidal blood flow and velocity in C3H/HeJ mice may contribute to the observed delay in the regenerative response in these mice. In addition, restoration of normal liver architecture may be delayed in TLR4-/- mice.

A STUDY ON THE EXCITATION AND RESONANT ABSORPTION OF CORONAL LOOP KINK OSCILLATIONS

ABSTRACT We study theoretically the issue of externally driven excitations of standing kink waves and their resonant absorption into torsionally polarized m = 1 waves in the coronal loops in pressureless plasmas. We use the ideal MHD equations, for which we develop an invariant imbedding method available in cylindrical geometry. We assume a sinusoidal density profile at the loop boundary where the density inside the loop is lower than the outside and vice versa. We present field distributions for these two cases and find that they have similar behaviors. We compare the results for the overdense loops, which describe the usual coronal loops, with the analytical solutions of Soler et al. obtained using the Frobenius method. Our results show some similarity for thin nonuniform layers but deviate a lot for thick nonuniform layers. For the first case, which describes the wave train propagation in funnels, we find that resonant absorption depends crucially on the thickness of the nonuniform boundary, loop length, and density contrast. The resonant absorption of the kink mode is dominant when the loop length is sufficiently larger compared with its radius (thin loop). The behavior of the far-field pattern of the scattered wave by the coronal loop is closely related to that of the resonant absorption. For the mode conversion phenomena in inhomogeneous plasmas, a certain universal behavior of the resonant absorption is found for the first time. We expect that the main feature may also apply to the overdense loops and discuss its relation to the damping rate.

Spleen histology in children with sickle cell disease and hereditary spherocytosis: hints on the disease pathophysiology

Hereditary spherocytosis (HS) and sickle cell disease (SCD) are associated with splenomegaly and spleen dysfunction in pediatric patients. Scant data exist on possible correlations between spleen morphology and function in HS and SCD. This study aimed to assess the histologic and morphometric features of HS and SCD spleens, to get possible correlations with disease pathophysiology. In a large series of spleens from SCD, HS, and control patients, the following parameters were considered: (i) macroscopic features, (ii) lymphoid follicle (LF) density, (iii) presence of perifollicular marginal zones, (iv) presence of Gamna-Gandy bodies, (v) density of CD8-positive sinusoids, (vi) density of CD34-positive microvessels, (vii) presence/distribution of fibrosis and smooth muscle actin (SMA)-positive myoid cells, and (viii) density of CD68-positive macrophages. SCD and HS spleens had similar macroscopic features. SCD spleens had lower LF density and fewer marginal zones than did HS spleens and controls. SCD also showed lower CD8-positive sinusoid density, increased CD34-positive microvessel density and SMA-positive myoid cells, and higher prevalence of fibrosis and Gamna-Gandy bodies. HS had lower LF and CD8-positive sinusoid density than did controls. No significant differences were noted in red pulp macrophages. By multivariate analysis, most HS spleens clustered with controls, whereas SCD grouped separately. A multiparametric score could predict the degree of spleen changes irrespective of the underlying disease. In conclusion, SCD spleens display greater histologic effacement than HS, and SCD-related changes suggest impaired function due to vascular damage. These observations may contribute to guide the clinical management of patients.

Multiphysics Modeling of a Lorentz Force-Based Meander Coil Electromagnetic Acoustic Transducer via Steady-State and Transient Analyses

Electromagnetic acoustic transducer (EMAT) is a kind of non-contact ultrasonic transducer, and during its operation, no liquid coupling is required. Despite this advantage, EMAT has low transduction efficiency and its performance depends on the tested object, thus further research of its complex multiphysics transduction mechanism involving both electromagnetic and elastodynamic phenomena is paramount. In this paper, an approach to solve directly the underlying integro-differential equations involved in the eddy current model was proposed, for both steady-state and transient analyses. Skin effect and proximity effect were observed in a generalized multi-conductor electromagnetic model, both for the complete and incomplete equations. Time-varying distributions of the Lorentz force vector were solved from the static bias magnetic field and sinusoidal current density waveforms converted from the corresponding complex phasors of the frequency-domain solution for a meander coil EMAT. For a plate model without any defect and a plate model with a slot defect, the waveforms of displacement component at two points from transient analyses were recorded. The simulated traveling velocities of the wave packets were calculated to compare with the theoretical group velocities of S0 and mode-converted A0 modes of Lamb waves.

Antiangiogenic and Antitumor Activities of Aflibercept, a Soluble VEGF Receptor-1 and -2, in a Mouse Model of Hepatocellular Carcinoma

BACKGROUND & AIM: Aflibercept known as ziv-aflibercept in the United States is a soluble decoy receptor of both vascular endothelial growth factor (VEGF) receptor-1 and -2 known to inhibit the binding of VEGF and placental growth factor (PlGF) to VEGF receptor-1 and -2. Here, we analyzed the mechanisms of the antitumor effects of aflibercept in mouse hepatoma models. METHODS: In in vitro studies, we determined the effects of aflibercept on human umbilical vein cell (HUVEC) proliferation and bone marrow (BM) cell differentiation to endothelial progenitor cells (EPCs). In in vivo experiments, aflibercept was injected intraperitoneally in hepatoma cell tumor-bearing mice, and its inhibitory effects on tumor growth and BM cell migration to tumor tissues were evaluated. RESULTS: Aflibercept suppressed phosphorylation of VEGF receptor-1 and -2 in HUVEC and dose-dependently inhibited VEGF-induced HUVEC proliferation. It suppressed the differentiation of BM cells to EPCs and migration of BM cells to tumor tissues. It also suppressed tumor growth and prolonged survival time of tumor-bearing mice without side effects. In tumor tissues, aflibercept upregulated the expression of hypoxia inducible factor1-α, VEGF, PlGF, fibroblast growth factor-2, platelet derived growth factor-BB, and transforming growth factor-α and reduced microvascular density. It also reduced sinusoidal density in noncancerous liver tissues. CONCLUSIONS: Our results demonstrated potent antitumor activity for aflibercept in a mouse model of hepatocellular carcinoma. These effects were mediated through inhibition of neovascularization, caused by inhibition of endothelial cell proliferation, EPC differentiation, and BM cell migration to tumor tissues.

Eddy current damper for passive reaction force compensation of a linear motor motion stage

This article presents an eddy current damper of a passive reaction force compensation mechanism for a linear motor motion stage. The reaction force compensation mechanism with a movable magnet track and eddy current damper resolves problems with the existing spring-based reaction force compensation mechanism such as resonance, design freedom, and difficulty of assembly and manufacturing. A simplified mathematical model of the eddy current damper is derived considering the sinusoidal magnetic flux density distribution and effective width of the eddy current damper, which shows important design factors of the eddy current damper–based reaction force compensation mechanism. Then, force of the eddy current damper according to the constant speed motion of the magnet track is investigated using multi-physical finite element analysis and is verified by experiments. Finally, the passive reaction force compensation with movable magnet track and eddy current damper is identified by experiments, and the finite element analysis of the eddy current damper is verified with free and forced vibration responses.

Design of a measurement system for investigating the magnetic characteristics of soft magnetic materials for non-sinusoidal periodic excitations

Abstract This article is about the design of a measurement system for measuring the iron losses in soft magnetic materials exerted by periodic flux density characteristics. The losses are due to hysteresis and eddy currents effects. The aim is to predict the iron losses which occur in electric machines. Common loss modeling techniques are derived by considering sinusoidal flux density characteristics. As nowadays highly-utilized machine designs with special winding topologies are employed, the periodic flux density characteristics in a big part of the ferromagnetic components are far off from being sinusoidal. Hence, the here presented measurement system and the associated control are especially developed for analyzing any periodic flux density characteristics. A further part of this article is dedicated to the comparison of state-of-the-art iron loss modeling techniques and measurement results. Several scenarios with different flux density harmonic magnitudes and frequencies are considered. It turns out that currently available loss modeling techniques show significant modeling errors for non-sinusoidal periodic flux density excitations. Thus, future work has to be on deriving more accurate models by considering their applicability for computer-aided engineering software.