Small Irregularities Research Articles

Analysis of results of the aggregate microtexture evaluation by volumetric characteristics

The article is concerned about the evaluation of aggregate microtexture. It is very important parameter from the traffic safety point of view and is described as a configuration of small irregularities on the aggregate surface. The new evaluating approach of aggregate microtexture based on the 3-D method is described in this article. 3-D model of surface of aggregate particle was generated from the measurements by microscope method. New program was developed for quantification of aggregate microtexture by a volumetric characteristics. Usability of this method was tested on samples of two coarse aggregate fraction taken from the eleven different quarries in Slovakia. The results of this evaluation have shown a high variability of values of volumetric characteristics between the fractions of aggregate and also between quarries.

Modeling of random ground roughness effects by an effective impedance and application to time-domain methods

Natural grounds can exhibit small scale geometric irregularities, compared to the acoustic wavelength, known as ground roughness. This roughness has a noticeable effect on sound pressure levels and produces a surface wave. In the context of prediction methods improvement for outdoor sound propagation, using an effective impedance appears to be an useful approach to model the effects of surface roughness. Two time-domain numerical methods are considered: finite difference schemes (FDTD), and the transmission line modeling (TLM) method. An effective impedance model for random ground roughness defined by a roughness spectrum, called the SPM model, is exposed. The efficiency of this model for taking into account the mean effects of random roughness on sound pressure levels and for modeling the roughness-induced surface wave is shown, by comparing with results of TLM simulations of propagation above random rough grounds. The direct implementation of the SPM model as a boundary condition in both TLM and FDTD methods is then studied. This approach allows the modeling of ground roughness effects in numerical methods without having to mesh finely the ground roughness profile, allowing easier and faster computations, and more accurate predictions for future impact studies in environmental acoustics.

Study on the scale distribution of the field-aligned irregularities in E-region

The field-aligned backscattering region in the ionospheric E-region is considered to contain many small irregularities, which are arrayed along the magnetic lines. The scale and number of these irregularities in the backscattering region are different. The irregularities of a certain scale can reflect the radio wave of the corresponding wavelength on the basis of the Bragg scattering theory. The more the irregularities of a scale, the stronger is the backscattered power. Thus, the scale distribution can be estimated by the function relationship between the scale and the echo amplitude, while the incidence direction of the wave path is perpendicular to the geomagnetic field. Moreover, the echoes with oblique incidence direction can also be used to estimate the scale distribution, considering the factor of the angle between the wave path and the perpendicular field direction.

Frequency correlation of probe waves backscattered from small scale ionospheric irregularities generated by high power HF radio waves

Aspect sensitive scattering of multi-frequency probe signals by artificial, magnetic field aligned density irregularities (with transverse size ∼1–10 m) generated in the ionosphere by powerful radio waves is considered. Fluctuations of received signals depending on stochastic properties of the irregularities are calculated. It is shown that in the case of HF probe waves two mechanisms may contribute to the scattered signal fluctuations. The first one is due to the propagation of probe waves in the ionospheric plasma as in a randomly inhomogeneous medium. The second one lies in non-stationary stochastic behavior of irregularities which satisfy the Bragg conditions for the scattering geometry and therefore constitute centers of scattering. In the probe wave frequency band of the order of 10–100 MHz the second mechanism dominates which delivers opportunity to recover some properties of artificial irregularities from received signals. Correlation function of backscattered probe waves with close frequencies is calculated, and it is shown that detailed spatial distribution of irregularities along the scattering vector can be found experimentally from observations of this correlation function.

Formation of transgressive anorthosite seams in the Bushveld Complex via tectonically induced mobilisation of plagioclase-rich crystal mushes

The formation of anorthosites in layered intrusions has remained one of petrology's most enduring enigmas. We have studied a sequence of layered chromitite, pyroxenite, norite and anorthosite overlying the UG2 chromitite in the Upper Critical Zone of the eastern Bushveld Complex at the Smokey Hills platinum mine. Layers show very strong medium to large scale lateral continuity, but abundant small scale irregularities and transgressive relationships. Particularly notable are irregular masses and seams of anorthosite that have intrusive relationships to their host rocks. An anorthosite layer locally transgresses several 10 s of metres into its footwall, forming what is referred to as a “pothole” in the Bushveld Complex. It is proposed that the anorthosites formed from plagioclase-rich crystal mushes that originally accumulated at or near the top of the cumulate pile. The slurries were mobilised during tectonism induced by chamber subsidence, a model that bears some similarity to that generally proposed for oceanic mass flows. The anorthosite slurries locally collapsed into pull-apart structures and injected their host rocks. The final step was down-dip drainage of Fe-rich intercumulus liquid, leaving behind anorthosite adcumulates.

A mathematical framework for virtual IMRT QA using machine learning.

It is common practice to perform patient-specific pretreatment verifications to the clinical delivery of IMRT. This process can be time-consuming and not altogether instructive due to the myriad sources that may produce a failing result. The purpose of this study was to develop an algorithm capable of predicting IMRT QA passing rates a priori. From all treatment, 498 IMRT plans sites were planned in eclipse version 11 and delivered using a dynamic sliding window technique on Clinac iX or TrueBeam Linacs. 3%/3 mm local dose/distance-to-agreement (DTA) was recorded using a commercial 2D diode array. Each plan was characterized by 78 metrics that describe different aspects of their complexity that could lead to disagreements between the calculated and measured dose. A Poisson regression with Lasso regularization was trained to learn the relation between the plan characteristics and each passing rate. Passing rates 3%/3 mm local dose/DTA can be predicted with an error smaller than 3% for all plans analyzed. The most important metrics to describe the passing rates were determined to be the MU factor (MU per Gy), small aperture score, irregularity factor, and fraction of the plan delivered at the corners of a 40 × 40 cm field. The higher the value of these metrics, the worse the passing rates. The Virtual QA process predicts IMRT passing rates with a high likelihood, allows the detection of failures due to setup errors, and it is sensitive enough to detect small differences between matched Linacs.

Existence of the stationary solution of a Rayleigh-type equation

A fluid flow along a semi-infinite plate with small periodic irregularities on the surface is considered for large Reynolds numbers. The boundary layer has a double-deck structure: a thin boundary layer (“lower deck”) and a classical Prandtl boundary layer (“upper deck”). The aim of this paper is to prove the existence and uniqueness of the stationary solution of a Rayleigh-type equation, which describes oscillations of the vertical velocity component in the classical boundary layer.

Seismic Ductility Reduction of Flexural-type Structures with Vertical Irregularities

Seismic ductility reduction factors for flexural-type structures with vertical irregularities subjected to pulse-like and non-pulse-like ground motions are investigated in this paper. By establishing various multi-node flexural cantilever-column models, the ductility reduction factor of vertically irregular structures is studied by modifying the ductility reduction factor of irregular structures. The effects of various factors such as ductility level, irregular ratio and pulse-like earthquake excitation on modification coefficient are also explored. The analysis results reveal that: 1) the modification coefficient decreases with smaller irregularity ratio; 2) ductility reduction factors for vertically irregular structures are significantly smaller than those of regular structures; 3) ductility level exerts a certain influence on ductility reduction factor without an obvious trend; and 4) the modification coefficient under pulse-like excitation is smaller than those from non-pulse-like motions and the influence of pulse-like earthquake is coupled with irregularity ratio. This paper concludes with the statistical outcomes based on average of results and recommends modified factors for practice uses.

Pavement distress detection and avoidance for intelligent vehicles

Pavement distresses and potholes represent road hazards that can cause accidents and damages to vehicles. The latter may vary from a simple flat tyre to serious failures of the suspension system, and in extreme cases to collisions with third-party vehicles and even endanger passengers' lives. The primary scientific aim of this study is to investigate the problem of road hazard detection for driving assistance purposes, towards the final goal of implementing such a technology on future intelligent vehicles. The proposed approach uses a depth sensor to generate an environment representation in terms of 3D point cloud that is then processed by a normal vector-based analysis and presented to the driver in the form of a traversability grid. Even small irregularities of the road surface can be successfully detected. This information can be used either to implement driver warning systems or to generate, using a cost-to-go planning method, optimal trajectories towards safe regions of the carriageway. The effectiveness of this approach is demonstrated on real road data acquired during an experimental campaign. Normal analysis and path generation are performed in post-analysis. This approach has been demonstrated to be promising and may help to drastically reduce fatal traffic casualties, as a high percentage of road accidents are related to pavement distress.

Boundary Layer for a Non-Newtonian Flow Over a Rough Surface

We analyze how small irregularities of a solid wall affect the steady flow of a non-Newtonian fluid. We consider the generalized Stokes system for power-law type fluids, with no-slip boundary conditions. Irregularities are modeled by small periodic variations of the boundary surface, described by a small parameter. We derive an effective boundary condition---a wall law---on a smoothed boundary, with the smallest possible approximation error (in terms of the parameter). The keypoint of the mathematical analysis is the study of the boundary layer generated by the irregularities. We stress that our results apply both to shear thickening and shear thinning fluids.

Evaluation of the TRMM 3B43 gridded precipitation estimates over Greece

The goal of this study is the assessment of the reliability of the V7 TRMM (Tropical Rainfall Measuring Mission) 3B43 gridded precipitation estimates over Greece. The validation was carried out using gridded monthly precipitation data derived from 96 meteorological stations over the wider region of Greece. The TRMM 3B43 gridded estimates are on a calendar month temporal resolution and 0.25°×0.25° spatial resolution concerning the 11-year period 1998–2008. In order to compare directly the TRMM 3B43 products with the rain gauge data, the latter were interpolated at the same spatial resolution grid with that of TRMM 3B43 (0.25°×0.25°) and a new Greek gridded precipitation database (GGPDB) was constructed, using Kriging spatial interpolation method, taking into account the altitude of the meteorological stations. Further, to ensure reliable ground truth, we performed the comparison using data only over the 0.25° grid box when/where at least one reporting gauge is available. The annual and seasonal spatial distribution of the differences between the two datasets along with the spatial distribution of the correlation coefficients are presented and analyzed.The findings of the analysis revealed that the correlations between the two examined gridded databases (satellite and ground based) in winter were very high (r>0.90) for the entire Greek domain with small exceptions over sparse data continental mountainous regions and restricted areas over north and south Aegean Sea. Regarding the other seasons, small correlations occur in the northern high altitude areas (Olympus Mt.) and the central/south mountainous Peloponnese. Besides, it is worth noting the remarkable small correlations over the eastern Aegean Sea and the Cyclades complex, in summer and the Cyclades complex in autumn. The TRMM 3B43 gridded data overestimate the precipitation over the Aegean and Ionian Sea, the coastal areas of Asia Minor and western Greece, in winter (>50mm), spring (>25mm) and autumn (>60mm). On the contrary, underestimation is demonstrated on central continental highlands (Pindus mountain range) and central mountainous Peloponnese in winter (>150mm), spring (25–100mm) and autumn (60–90mm). Summer is generally characterized by small irregularities. Generally, the findings of the performed validation indicate an underestimation at higher precipitation appeared over high altitude areas against some overestimation at lower precipitation over plains and coastal regions. The TRMM 3B43 products performance was assessed by using three contingency statistics for probability of detection (POD), false alarm ratio (FAR) and critical success index (CSI). TRMM 3B43 has POD>80% and CSI>60% when the monthly precipitation is lower than 84.0mm. Moreover, the smallest POD of 44% and CSI of 34% appear when the monthly precipitation is greater than 191.5mm. This result implies that satellite products have poor performance in estimating high monthly precipitation totals, over the Greek region.

The presence of lysyl oxidase-like enzymes in human control and keratoconic corneas.

Lysyl oxidases, a family comprising lysyl oxidase (LOX) and four LOX-like enzymes (LOXL1-4), catalyse the cross-linking of elastin and collagen fibrils. Keratoconus (KC) is characterized by progressive thinning leading to irregular astigmatism, resulting in significant visual impairment. Although the pathogenesis of KC remains unclear, one of the current hypotheses is based on alterations in the organization and structure of collagen fibrils. To extend existing general knowledge about cross-linking enzymes in the human cornea, in the present study we have focused on the detection of LOXL enzymes. The localization and distribution of LOXL1-4 were assessed in cryosections of 7 control donors (three males and three females; 25-68 years; mean age 46±17.6 years) and 8 KC corneas (5 males and 3 females; 25-46 years; mean age 31.3±7.5 years) using indirect fluorescent immunohistochemistry (IHC). The specimens were examined using an Olympus BX51 microscope (Olympus Co., Tokyo, Japan) at a magnification of 200-1000x. Western blot analysis of 4 control and 4 KC corneas was performed for all tested enzymes. All four LOX-like enzymes were present in all layers of control corneas as well as in the limbus and conjunctiva. Almost no differences between control and pathological specimens were found for LOXL1. A lower staining intensity of LOXL2 was found using IHC and Western blot analysis in KC specimens. Decreases of the signal and small irregularities in the staining were found in the epithelium, keratocytes and extracellular matrix, where a gradual anterior-posterior weakening of the signal was observed. LOXL3 IHC staining was lower in the corneal stromal extracellular matrix and keratocytes of KC samples. No prominent differences were detected using IHC for LOXL4, but a slight decrease was observed in KC corneas using Western blot analysis. We presume that the decrease of LOXL2 in KC corneas is more likely a consequence of the associated pathological processes (activation of stromal cells due to tissue weakening and consequent structural changes) than a direct cause leading to KC development. At this time, we are unable to provide a coherent explanation for the observed decrease of LOXL3 and LOXL4 in KC corneas.

Novel use of immunohistochemistry for phenotypic evaluation of circulating neoplastic lymphocyte populations

CASE HISTORY: A 5-year-old male neutered Poodle cross presented with a 2-week history of non-specific gastrointestinal signs including vomiting, inappetence and lethargy (Case 1). A 14-year-old male neutered Staffordshire Bull Terrier presented with a 6-week history of progressive inappetence and lethargy (Case 2).CLINICAL FINDINGS: On presentation, Case 1 was dehydrated and had repeatable cranial abdominal pain. Mild hypoproteinemia with hypoalbuminemia, and electrolyte disturbances were found on biochemistry profile. Abdominal ultrasonography showed moderate diffuse small intestinal wall irregularity and moderate local lymphadenopathy. Haematology was repeated 2 days after initial presentation and showed a marked leucocytosis associated with an elevated circulating neoplastic cell population. On presentation, Case 2 was dehydrated, had palpable hepatomegaly and a mild generalised lymphadenopathy. A low number of large, atypical lymphocytes were found on haematology. Sonographically there was hepatomegaly with diffuse parenchymal changes and severe mesenteric lymphadenopathy.LABORATORY FINDINGS: Aspirates from the abdominal lymph nodes (Cases 1 and 2) and liver (Case 2), and blood smears revealed atypical neoplastic lymphoid populations, predominantly comprising large lymphocytes.Immunocytochemistry failed to determine the lymphoid phenotype in Case 1 but supported a T cell phenotype in Case 2. Immunohistochemistry of formalin-fixed paraffin-embedded (FF-PE) blood clots was able to identify a T cell phenotype in both cases. PCR for antigen receptor rearrangement results from both cases were consistent with an expanded T cell population.DIAGNOSIS: In both cases, immunohistochemistry on FF-PE blood clots revealed a circulating T cell lymphocyte population, consistent with T cell lymphoproliferative neoplasia.CLINICAL RELEVANCE: Immunohistochemistry on FF-PE blood clots offers clinicians a reliable, inexpensive and minimally invasive method of phenotyping neoplastic cells in circulation. Compared to other available methods, prolonged sample stability allowing for transport and retrospective examination is a distinct advantage. This technique should be considered a useful adjunct to the currently available methods for the phenotypic evaluation of lymphoid leukaemia in dogs.

Performance of the L2C civil GPS signal under various ionospheric scintillation effects

As GPS is modernizing, there are currently fourteen satellites transmitting L2C civil code and seven satellites transmitting L5 signal. While the GPS observables are subject to several sources of errors, the ionosphere is one of the largest error sources affecting GPS signals. Small irregularities in the electrons density along the GPS radio signal propagation path cause ionospheric scintillation that is characterized by rapid fluctuations in the signal amplitude and phase. The ionospheric scintillation effects are stronger in equatorial and high-latitude geomagnetic latitude regions and occur mainly due to equatorial anomaly and solar storms. Several researchers have analyzed the L2C signal quality since becoming available in December, 2005. We analyze the performance of L2C using GPS data from stations in the equatorial region of Brazil, which is subject of weak, moderate and strong ionospheric scintillation conditions. The GPS data were collected by Septentrio PolaRxS---PRO receivers as part of the CIGALA/CALIBRA network. The analysis was performed as a function of scintillations indexes S4 and Phi60, lock time (time interval in seconds that the carrier phase is tracked continuously without cycle slips), multipath RMS and position variation of precise point positioning solutions. The analysis shows that L2C code solutions are less affected by multipath effects than that of P2 when data are collected under weak ionospheric scintillation effects. In terms of analysis of positions, the kinematic PPP results using L2C instead P2 codes show accuracy improvements up to 33 % in periods of weak or strong ionospheric scintillation. When combining phase and code collected under weak scintillation effects, the results by applying L2C against P2 provide improvement in accuracy up to 59 %. However, for data under strong scintillation effects, the use of L2C for PPP with code and phase does not provide improvements in the positioning accuracy.

Vortices in the Prandtl boundary layer induced by irregularities on a plate

A fluid flow along a plate with small irregularities on the surface is considered for large Reynolds numbers. The boundary layer has a double-deck structure, i.e., both a thin boundary layer and the classical Prandtl boundary layer are present. It is proved that the solution of the boundary-value problem thus obtained exists and is unique in the Prandtl boundary layer, and the stability of the solution is investigated at large times. The results of numerical modeling are given. Supported by the Basic Research Program of the National Research University “Higher School of Economics.”

Transverse Musculocutaneous Gracilis Flap for Treatment of Capsular Contracture in Tertiary Breast Reconstruction

Capsular contracture is a common complication associated with implant-based breast reconstruction and augmentation leading to pain, displacement, and rupture. After capsulectomy and implant exchange, the problem often reappears. We performed 52 deepithelialized free transverse musculocutaneous gracilis (TMG) flaps in 33 patients for tertiary breast reconstruction or augmentation of small- and medium-sized breasts. The indications for implant removal were unnatural feel and emotion of their breasts with foreign body feel, asymmetry, pain, and sensation of cold. Anyway, most of the patients did not have a severe capsular contracture deformity. The TMG flap is formed into a cone shape by bringing the tips of the ellipse together. Depending on the contralateral breast, the muscle can also be shaped in an S-form to get more projection if needed. The operating time for unilateral TMG flap breast reconstruction or augmentation was on average 3 hours and for bilateral procedure 5 hours. One patient had a secondary revision of the donor site due to disruption of the normal gluteal fold. Eighty percent of the unilateral TMG flap reconstructions had a lipofilling procedure afterward to correct small irregularities or asymmetry. The advantages of the TMG flap such as short harvesting time, inconspicuous donor site, and the possibility of having a natural breast shape make it our first choice to treat capsular contracture after breast reconstruction and augmentation.

Spin injection from a ferromagnet into a semiconductor in the case of a rough interface

The effect of the interface roughness on the spin injection from a ferromagnet into a semiconductor is studied theoretically. Even a small interface irregularity can lead to a significant enhancement of the injection efficiency. When a typical size of the irregularity, a, is within a domain lambda_F << a << lambda_N, where lambda_F and lambda_N are the spin-diffusion lengths in the ferromagnet and semiconductor, respectively, the geometrical enhancement factor is ~lambda_N. The origin of the enhancement is the modification of the local electric field on small scales ~a near the interface. We demonstrate the effect of enhancement by considering a number of analytically solvable examples of injection through curved ferromagnet-semiconductor interfaces. For a generic curved interface the enhancement factor is ~lambda_N / R, where R is the local radius of curvature.

EFFECT OF VARIABLE INPUT AND OUTPUT ON THE CHARACTERISTICS OF A STEERING SYSTEM WITH EPS (ELECTRIC POWER SYSTEM)

The complexity of the process of controlling the steering system assistance causes that the assistance units, designed as the control systems, change their characteristics depending on the frequency and amplitude of the torque applied to the steering wheel as well as on the frequency and amplitude of the force applied to the gear toothed bar. The investigation aiming to indicate this effect involved designing a special test stand enabling differentiation of the frequency and amplitude of the input functions applied to the steering wheel or to the gear-toothed bar. The results of the investigation are the characteristics diagrams and numerically determined friction force and compliance values. The test stand allows carrying out the research in two operation modes of the assistance device – normal mode and city mode as well as at simulated different driving speeds. The investigation permitted to identify the parameters of the model of a steering system with an electric assistance device. In the paper, the results of the investigation and their preliminary analysis are presented. The load input function from the side of the toothed bar showed a strong relationship between the frequency and the torque transmitted on the steering wheel. For example, high frequencies occurring during running fast through small irregularities of the road are strongly damped. The slow-variable runs are transmitted on the steering wheel as a feedback reaction.

Magnetic properties of the multiferroic compounds Eu1-xYxMnO3 (x = 0.2 and 0.3)

Magnetic properties of multiferroic Eu1-xYxMnO3 with x = 0.2, 0.3 were studied by μSR and Mossbauer spectroscopy. Both compounds are known to become antiferromagnetic with Mn3+ being the only magnetic ion. We find TN = 47±0.5K for x = 0.2 and 45±0.5K for x = 0.3. Below TN three different magnetic states (AFM-1, AFM-2, AFM-3) are formed. The μSR parameters of the uppermost magnetic state (AFM-1) are alike in both compounds, and compatible with a commensurate modulated collinear spin structure. The magnetic ground state in x = 0.2 (AFM-3) is shown to be single phase. Its spectral parameters support the proposal of a cone-like spin structure, yet with incommensurate modulation. The ground state for x = 0.3 is found to have an incommensurate spiral spin structure. 151Eu Mössbauer spectroscopy measured the Eu hyperfine field induced by the Mn3+ ions. Its low value (~4T) means that mixing with higher Eu electronic states is small and that the Mn-Eu exchange coupling is weak (~0.5K). The various magnetic transitions appear as small irregularities in the temperature dependence of the hyperfine fields. The present results are discussed in terms of different published magnetic phase diagrams of Eu1-xYxMnO3.

Morphometric Characterization of Small Cell Lymphocytic Lymphoma

Abstract The morphometry in histopathology is used to characterize cell populations belonging to different tissues and to identify differences in their parameters with prognostic implications. To achieve morphometric examination were selected 6 of 24 cases identified as small cell lymphocytic lymphoma. For each case analysis was done on five fields, for each field measuring the parameters of 20 cells. The studied parameters were for cytoplasm: cytoplasmic area, maximum and minimum cytoplasmic diameter, cytoplasmic perimeter; for nucleus were measured: nuclear area, minimum and maximum nuclear diameter, nuclear perimeter, nuclear contour index, nuclear ellipticity index, nuclear irregularity index. Also the nucleocytoplasmic ratio was calculated in all studied cases. Small cell lymphocytic lymphoma is characterized in morphometric terms having a small cytoplasmic area (average 29.206) and also a small nuclear area (mean 28.939) having a nucleo-cytoplasmic ratio appearance suggestive for adult lymphocyte. A nuclear contour index small value (3.946), ellipticity index value also small (3.521) and small nuclear irregularity index (3.965). Standard deviations, in any of the studied morphometric categories, is around or below 1 suggesting monomorphic cell appearance. These morphometric and microscopic features characterized mainly by a small population of adult lymphocytes, monomorphic, with rounded hipercromic nuclei, dense chromatin, support the framing into indolent lymphoma group in terms of clinical outcome.