bluuebunny/crossref_metadata_2025 huggingface dataset:
Transverse strength of railway tracks: part 1. Planning and experimental setup
Authors: De Iorio Antonio , Grasso Marzio , Penta Francesco , Pucillo Giovanni Pio , Pinto Paolo , Rossi Stefano , Testa Mario , Farneti Giuseppe
Published: July 2018

Several studies have been carried out until now by various Research Agencies and Railway Administrations to quantify the effects of the track-bed geometrical characteristics on the transverse strength of the track. Unfortunately, not all the possible scenarios in terms of track components, track-bed cross profile, operating conditions etc. have been investigated and not all the relevant variables have been directly measured. Therefore data available from the literature have different degrees of reliability. With the aim of enlarging the knowledge on the track stability and covering much of the possible relevant scenarios, an experimental research program has been developed in the framework of a cooperation between RFI, Italcertifer and DII. In order to perform the investigation under quite general conditions and to reduce the experimentation costs, n. 28 significant scenarios have been identified and reproduced on as many independent track segments. By applying on each track segment a transversal load, the strength of the ballast-sleeper interface has been determined. The results relative to the first four scenarios are presented in terms of applied load vs. lateral track displacement diagrams and in more synthetic numerical tables.
Measurement and simulation of strain fields around crack tips under mixed-mode fatigue loading
Authors: Hos Y. , Vormwald M. , Freire J.L.F.
Published: July 2018

For various configurations examined in a series of fatigue experiments on thin-walled tubes under tension and torsion, the experimental results – crack path, crack growth life, near crack tip deformations, and crack closure – are measured and compared to the results of some numerical simulations. Partially automated optical inspection and the digital image correlation technique were used in the experimental investigation. In the finite element analyses, an actual geometry of a cracked structure has been modeled. The mechanical material behavior has been assumed as linear elastic in a first approach for calculating stress intensity factors. The nonlinear nature of the cyclic deformation has been taken into account by applying a cyclic plasticity model, and plasticity-induced crack closure is captured by a contact formulation.
3D thickness effects around notch and crack tip stress/strain fields
Authors: Góes R.C.O. , Castro J.T.P. , Meggiolaro M.A.
Published: July 2018

Notches and cracks are usually approximately modeled as two-dimensional problems using solutions from plane elasticity to quantify localized stress/strain concentration effects around their tips. However, they may be associated with high gradients that can severely restrict local Poisson-induced transversal strains and cause important 3D stress fields around those tips. Fatigue crack initiation and growth, plastic zone sizes and shapes, and localized constraint effects that affect toughness are typical problems associated with such 3D effects, which may lead to non-conservative damage and life predictions if neglected. To quantify how important they can be, first finite element techniques are used to simulate thickness and notch-tip radius effects in the fields around such tips, and to evaluate their importance from the structural design point of view. Then, versatile sub-modeling techniques are used to study similar effects along the fronts of short and long cracks, and a stepwise re-meshing routine is used to show how an initially straight crack must slightly curve its front during its propagation by fatigue, due to the unavoidable 3D effects that always surround real crack tips.
Can ?Keff be assumed as the driving force for fatigue crack growth?
Authors: Castro J.T.P. , Meggiolaro M.A. , González J.A.O.
Published: July 2018

This work raises some new questions about the validity of blindly assuming that Elber’s effective stress intensity factor is the actual fatigue crack driving force, and that as so it can be used to explain all load sequence effects on fatigue crack growth (FCG). Although plasticity-induced crack closure can be a quite reasonable heuristic explanation for many non-elementary FCG behaviors, it has some limitations that cannot be ignored. In fact, this never settled discussion is particularly important for the simulation of FCG lives under real service loads, a most important practical issue. After arguing that ?Keff can spoil the use of the most important similitude principle in FCG problems, simple but convincing experimental data that cannot be explained by this classical idea is presented here. This data involves the shape of fatigue crack fronts and the FCG behavior under nominally plane stress and plane strain conditions.
Growth of inclined fatigue cracks using the biaxial CJP model
Authors: Laboviciute G. , Christopher C. J. , James M. N. , Patterson E. A.
Published: July 2018

The CJP model of crack tip stresses is a modified version of the Williams crack tip stress field which takes account of simplified stress distributions that arise from the presence of a zone of plastic deformation associated with the crack flanks and crack tip, and that act on the elastic field responsible for driving crack growth. The elastic stress field responsible for crack growth is therefore controlled by the applied loading and by the induced boundary stresses at the interface with the plastic zone. This meso-scale model of crack tip stresses leads to a modified set of crack tip stress intensity factors that include the resultant influence of plastic wake-induced crack tip shielding, and which therefore have the potential to help resolve some longstanding controversies associated with plasticity-induced closure. A full-field approach has now been developed for stress using photoelasticity and also for displacement using digital image correlation. This paper considers the characterisation of crack growth rate data with the biaxial CJP model, using compact tension specimens that contain inclined cracks at the notch tip with initial angles of 30°, 45° and 60° to the horizontal axis. Significant experimental difficulties are experienced in growing cracks in a biaxial field under uniaxial tensile loading, as the natural tendency of the crack is to turn so that it becomes perpendicular to the maximum principal stress direction. However, crack angle is not an issue in the CJP model which calculates the stress field parallel with, and perpendicular to, the crack plane. These stress components can be rotated into directions comparable with the usual KI and KII directions and used to calculate stress intensity parameters that should be directly comparable with the standard stress intensity formulations. Another difficulty arises, however, in finding published expressions for KI and KII for CT specimens with curved or kinked cracks. The CJP model has been successful in achieving a sensible rationalisation of crack growth rate data for the specimens considered in this work, although some observations are not easily explained. Nonetheless, considering the complexity of characterising crack growth rates for cracks with an initial orientation of 30°, 45° or 60° to the horizontal and which subsequently change angle during growth, the results found so far indicate that there is value in further pursuing the CJP approach. The paper introduces future research directions for the CJP model.
Estimation of fatigue life of selected construction materials under cyclic loading
Authors: Kurek M. , agoda T. , Vantadori S.
Published: July 2018

In the literature, there are many criteria of multiaxial fatigue. They are based on various assumptions and parameters describing the process of fatigue. Among them, there is a special group of criteria based on the concept of critical plane. Some of them in their equations take into account the ratio of normal and shear stresses. Macha has formulated the criterion of maximum normal and shear stress in fracture plane which can be generalised for the scope of random loading of numerous criteria. In the present study authors estimated the fatigue life of several construction materials. For the purposes of the analysis, the authors proposed modified Carpinteri et al. method to find orientation of critical plane, which is used in multiaxial fatigue criterion defined in critical plane. This plane is turned through the angle of ? in relation to the plane defined by maximum normal stresses. In this study authors analyzed the variability calculation of fatigue life, depending on the angle ?. Simulation studies were conducted in which it was assumed that ? ? . For each of the 46 angles, we calculated parameters B and K appearing in the formula defining equivalent stress. Then we calculated fatigue life according to the proposed model for each of the obtained angles ?. Fatigue life analysis was carried out in order to verify which angle ? gives the most similar results.
Fast assessment of the critical principal stress direction for multiple separated multiaxial loadings
Authors: Cova M. , Livieri P. , Tovo R.
Published: July 2018

The critical plane calculation for multiaxial damage assessment is often a demanding task, particularly for large FEM models of real components. Anyway, in actual engineering requests, sometime, it is possible to take advantage of the specific properties of the investigated case. This paper deals with the problem of a mechanical component loaded by multiple, but “time-separated”, multiaxial external loads. The specific material damage is dependent from the max principal stress variation with a significant mean stress sensitivity too. A specifically fitted procedure was developed for a fast computation, at each node of a large FEM model, of the direction undergoing the maximum fatigue damage; the procedure is defined according to an effective stress definition based on the max principal stress amplitude and mean value. The procedure is presented in a general form, applicable to the similar cases.
Comparison of two multiaxial fatigue models applied to dental implants
Authors: Ayllon JM. , Navarro C , Vázquez J. , Domínguez J.
Published: July 2018

This paper presents two multiaxial fatigue life prediction models applied to a commercial dental implant. One model is called Variable Initiation Length Model and takes into account both the crack initiation and propagation phases. The second model combines the Theory of Critical Distance with a critical plane damage model to characterise the initiation and initial propagation of micro/meso cracks in the material. This paper discusses which material properties are necessary for the implementation of these models and how to obtain them in the laboratory from simple test specimens. It also describes the FE models developed for the stress/strain and stress intensity factor characterisation in the implant. The results of applying both life prediction models are compared with experimental results arising from the application of ISO-14801 standard to a commercial dental implant
Models of initiation fatigue crack paths proposed by Macha
Authors: Marciniak Z. , Rozumek D.
Published: July 2018

Professor E. Macha devoted his academic life to solving the problems connected with random multiaxial fatigue in components of machines and structures. In his studies he formulated stress, strain and energy criteria related to critical plane concept. He also proposed several methods to determine critical plane position. In particular, he formulated and verified weight functions applied in order to determine critical plane position. The variance method constituted another significant contribution to the development of methods for determining critical plane position. Apart from these criteria, Macha was exploring energy approach in fatigue of materials and the development of fatigue cracks. He has also observed that strain characteristics multiplied by stress amplitude determined at specimen half-life are applied to estimate fatigue life using energy criteria. However, for cyclically instable materials, stress amplitude value may differ a lot; therefore he proposed the method to determine energy fatigue characteristics directly from experimental research.
Fracture morphology and its evolution A review on crack path stability and brittle fracture along butt-weld
Authors: Sumi Y.
Published: July 2018

Considerations are made for the fracture morphology and its evolution in relation to the brittle fracture along butt-weld, where crack path stability may play important roles in various aspects. Analyses of a kinked and curved crack are first reviewed in the present paper. Having learned the solutions of a kinked and curved crack, several crack path criteria are compared for the crack path prediction. Then, some aspects of stability of a crack path are examined as to whether it may propagate, keeping its original direction or not in a homogeneous material, and whether crack kinking in a material having inhomogeneous fracture toughness may be predicted by seeking the state which gives rise to an energetically stable one. Having reviewed the morphology of brittle crack propagation along butt-weld, brittle fracture of extremely thick plates of high tensile steel is discussed for the fracture control of recently emerging large container ships.
A unified approach for static and dynamic fracture failure in solids and granular materials by a particle method
Authors: Brighenti Roberto , Carpinteri Andrea , Corbari Nicholas
Published: July 2018

The material structure at the microscale reveals the particulate nature of solids. By exploiting the discrete aspect of materials, the so-called particle methods developed and applied to the simulation of solids and liquids have attracted the attention of several researchers in the field of computational mechanics. In the present paper, a particle method based on a suitable force potential is proposed to describe the nature and intensity of the forces existing between particles of either the same solid or different colliding solids. The formulation applies to problems involving both granular materials and solids interacting with granular materials. The above approach is applied to simulate different problems dealing with the 3D dynamic fracture and failure of solids.
Measurement and simulation of crack growth rate and direction under non-proportional loadings
Authors: Hos Y. , Vormwald M.
Published: July 2018

A series of fatigue experiments on thin-walled tubes under tension and torsion, the experimental results – crack path and crack growth life – are measured and compared. It is observed that the cracks follow a curvature from a tensile to a shear dominated growth with increasing crack length. The results are enforced by the high amplitudes applied to the specimens causing large cyclic plastic deformations and crack growth rates in the order of 10-3 mm/cycle. The non-linear nature of the cyclic deformation has been taken into account by applying a cyclic plasticity model, and plasticity-induced crack closure is captured by a contact formulation. Already for the uniaxial reference case the current limitations in modelling plasticity induced crack closure – a prerequisite for achieving realistic simulation results – have become obvious. Measurements have shown that friction and roughness induced closure processes come up, especially for non-planar crack surfaces, challenge to be met in the future.
Fatigue cracking of aluminium alloy AlZn6Mg0.8Zr subjected to thermomechanical treatment
Authors: Kowalski A. , Ozgowicz W. , Kurek M. , Kurek A. , Lagoda T.
Published: July 2018

The paper presents the results of experimental test of the fatigue of aluminium alloy type AlZn6Mg0,8Zr exposed to various low temperature thermomechanical treatment. Basquin’s characteristics of fatigue have been determined in mechanical test on smooth specimens at a simple state of loading in conditions of alternating bending. The tests were carried out on a fatigue test stand constructed by the authors – MZGS 100. The development of fatigue cracking has been described based on metallographic and fractographic investigations of the fractured samples making use of a scanning electron microscope (SEM). The results of qualitative microfractography of the tested samples in the low-cycle temporal range of fatigue strength revealed fractures of the transcrystalline quasi-cleavage type. It has also been found that local effects of intercrystalline brittle cracking of this type do occur.
Damage of bamboo and wooden materials based on linear elastic fracture mechanics in garden design
Authors: Haiyan Tang
Published: July 2018

Bamboo and wood are the most widely applied and the oldest natural structural materials in the world. Currently, worldwide output of wooden material is 1 billion ton, almost the same as steel. Most of them are used as structure, such as load carrying girder, scaffold, floor and support. Wooden materials and bamboo materials with clear microstructure are composite biomaterials which can be studied under multiple scales. Irregular evolution behaviors of initial defects or damage during loading determines macro mechanical behavior of wooden and bamboo materials. Taking wood and bamboo as test materials, this study explored mechanical characteristics and damage crack behavior of wood and bamboo as well as toughening mechanism.
The non-proportionality of local stress paths in engineering applications
Authors: Riess C. , Obermayr M. , Vormwald M.
Published: July 2018

A scalar measure, which describes the non-proportionality of local stress paths in engineering applications, is introduced. For this purpose the moment of inertia approach by Meggiolaro is modified in a way that the stress time history is evaluated in a tresca-stress-space. This modification makes the non-proportionality factor invariant with respect to the coordinate system. An optimization procedure is implemented to derive a test set-up for new component tests with 2 load channels. The aim of the planned tests is to get a high non-proportionality at the potential crack initiation site. It is not possible to obtain a high non-proportionality factor at the failure location without selective weakening of the component (housing of a rear axle steering). Therefore specific areas of the structure are cut out and the optimization procedure is repeated. As a result of the optimization a test set-up with high local non-proportionality at the potential crack initiation site is achieved for the weakened structure. Another set-up with slightly less non-proportionality but with a very localized damage is derived. This set-up is preferred, because of the robustness in the physical test.
Comparative study of multiaxial fatigue methods applied to welded joints in marine structures
Authors: van Lieshout P.S. , den Besten J.H. , Kaminski M.L.
Published: July 2018

Marine structures are particularly prone to action of waves, winds and currents with stochastically varying composition, intensities and directions. Therefore, resultant stresses may cause multiaxial fatigue in specific welded structural details. For the assessment of multiaxial fatigue in welded joints, a wide variety of methods have been suggested. However, there is still no consensus on a method which can correctly account for non-proportional and variable amplitude loading. This paper beholds a comparative study of multiaxial fatigue methods applicable for design of marine structures. For the purpose of comparison several load cases were defined including non-proportional and variable amplitude loadings with different normal and shear stress amplitude ratios. Three types of methods are compared: those described by three different codes (i.e. Eurocode 3, IIW and DNV-GL), those described by three different multiaxial fatigue approaches from literature (i.e. Modified Carpinteri-Spagnoli Criterion, Modified Wohler Curve Method and Effective Equivalent Stress Hypothesis) and an approach based on Path-Dependent-Maximum-Range multiaxial cycle counting. From this study it has been concluded that non-proportional variable amplitude loading has a significant negative impact on the fatigue lifetime estimates, and that further research and experimental testing are essential to come to a consensus.
Experimental investigation of hardness of FSW and TIG joints of Aluminium alloys of AA7075 and AA6061
Authors: Patil Chetan , Patil Hemant , Patil Hiralal
Published: July 2018

This paper reports hardness testing conducted on welded butt joints by FSW and TIG welding process on similar and dissimilar aluminium alloys. FSW joints were produced for similar alloys of AA7075T651 and dissimilar alloys of AA7075T651- AA6061T6. The Friction stir welds of AA7075 & AA6061 aluminium alloy were produced at different tool rotational speeds of 650,700, 800, 900, 1000 and transverse speed of 30, 35, 40 mm/min. TIG welding was conducted along the rolling direction of similar and dissimilar aluminium plates. The Brinell hardness testing techniques were employed to conduct the tests; these tests were conducted on the welds to ascertain the joint integrity before characterization to have an idea of the quality of the welds
Comparison of fracture toughness values of normal and high strength concrete determined by three point bend and modified disk-shaped compact tension specimens
Authors: Seitl Stanislav , Ríos José D. , Cifuentes Hector
Published: July 2018

The modified disk shaped compact tension test is a configuration derived from standard compact tension test that is used for measuring fracture mechanical properties of primarily metallic materials. The compact tension configuration is commonly used for measurement fracture mechanical properties as e.g. fracture toughness, Young’s modulus, work of fracture etc. The modified compact tension tests imply significant modifications of the specimen morphology in order to avoid premature failure. The modified compact tension test is not proper for quasi-brittle materials due to its complicated shape (steel-concrete interface), but it is easily extracted from drill core and we do not need large amount of material for obtaining fracture properties as we need for e.g. three- or four- point bend test. Since it is a new test method, a wide range of tests is needed to be done before it can be applied. In the paper the selected outputs of the experiments performed on normal and high strength concrete will be processed and the values of fracture mechanical parameters will be discussed.
Fatigue crack propagation prediction of a pressure vessel mild steel based on a strain energy density model
Authors: Huffman P. J. , Ferreira J. , Correia J.A.F.O. , De Jesus A.M.P. , Lesiuk G. , Berto F. , Fernandez-Canteli A. , Glinka G.
Published: July 2018

Fatigue crack growth (FCG) rates have traditionally been formulated from fracture mechanics, whereas fatigue crack initiation has been empirically described using stress-life or strain-life methods. More recently, there has been efforts towards the use of the local stress-strain and similitude concepts to formulate fatigue crack growth rates. A new model has been developed which derives stress-life, strain-life and fatigue crack growth rates from strain energy density concepts. This new model has the advantage to predict an intrinsic stress ratio effect of the form ?ar=(?amp)?·(?max )(1-?), which is dependent on the cyclic stress-strain behaviour of the material. This new fatigue crack propagation model was proposed by Huffman based on Walkerlike strain-life relation. This model is applied to FCG data available for the P355NL1 pressure vessel steel. A comparison of the experimental results and the Huffman crack propagation model is made.
Pilot evaluation of a fracture process zone in a modified compact tension specimen by X-ray tomography
Authors: Klon Jiri , Seitl Stanislav , Simonova Hana , Kersner Zbynek , Kumpova Ivana , Vavrik Daniel
Published: July 2018

In the case of quasi-brittle material, there is a zone of non-linear behaving material, near the crack tip. A major part of this zone forms a socalled fracture process zone (FPZ), where mechanisms of material toughening take place. The main idea is to estimate the size of the fracture process zone under various types of load by using X-ray tomography. The estimation of the zone is supported by the theory of linear elastic fracture mechanics (LEFM) that could be a limit case of quasi-brittle mechanics. The size of the zone envelop is provided in X-ray snaps and compared with the theoretical size from LEFM.
Background Subtraction Based on a New Fuzzy Mixture of Gaussians for Moving Object Detection
Authors: Darwich Ali , Hébert Pierre-Alexandre , Bigand André , Mohanna Yasser
Published: July 2018

Moving foreground detection is a very important step for many applications such as human behavior analysis for visual surveillance, model-based action recognition, road traffic monitoring, etc. Background subtraction is a very popular approach, but it is difficult to apply given that it must overcome many obstacles, such as dynamic background changes, lighting variations, occlusions, and so on. In the presented work, we focus on this problem (foreground/background segmentation), using a type-2 fuzzy modeling to manage the uncertainty of the video process and of the data. The proposed method models the state of each pixel using an imprecise and adjustable Gaussian mixture model, which is exploited by several fuzzy classifiers to ultimately estimate the pixel class for each frame. More precisely, this decision not only takes into account the history of its evolution, but also its spatial neighborhood and its possible displacements in the previous frames. Then we compare the proposed method with other close methods, including methods based on a Gaussian mixture model or on fuzzy sets. This comparison will allow us to assess our method’s performance, and to propose some perspectives to this work.
The activity of the Clinic of Ophthalmology as the subunit of the Faculty of Medicine of the University of Lithuania (Vytautas Magnus University) during 1922–1938
Authors: Lignugarienė Asta , Petrauskienė Jadvyga , Kaselienė Snieguolė
Published: July 2018

The aim of the study was to evaluate the activity and the validity of the expansion of the Clinic of Ophthalmology of the University of Lithuania (since 1930 – Vytautas Magnus University) operating in Kaunas city between 1922 and 1938. The evaluation was based on the analysis of changes in inpatient and outpatient flow, the structure of cases of inpatient treatment, and the usage of beds. In the analysis, we used annual reports of the Clinic of Ophthalmology as well as data presented in statistical publications of the Department of Health for the studied period. The changes in the indices of the activity of the Clinic were evaluated using the logarithmic regression coefficient. A more rapid increase in the number of patients discharged from the Clinic of Ophthalmology was observed during 1922–1930 (on the average, by 9% per year). During 1931–1938, only the number of discharged men was increasing. During the studied period, the majority of the cases of inpatient treatment were lenticular diseases (19%), trachoma (16%), and corneal diseases (16%). During 1922–1930, the sharpest increase was observed in the number of inpatients with eyeball diseases and eye traumas (on the average, by 12.3% per year) and during 1931–1938, in the number of patients with trachoma (on the average, by 6.7% per year). The analysis of the indices of the activity of the inpatient unit confirmed the need for the expansion of the Clinic during 1922–1930, but revealed that the expansion of the material basis of the Clinic up to 50 beds during 1931–1938 was not efficient. In the outpatient unit of the Clinic of Ophthalmology, the number of visits per year and the number of admitted patients per year during the studied period increased by 2.5 and 3.5 times, respectively.
Transition zone volume measurement – is it useful before surgery for benign prostatic hyperplasia?
Authors: Milonas Daimantas , Matjošaitis Aivaras , Jievaltas Mindaugas
Published: July 2018

Objective. The aim of this study was to estimate the equivalence and correlation between transition zone volume, measured by transrectal ultrasound, and removed prostate tissue weight in surgically treated patients due to benign prostatic hyperplasia. Material and methods. This study involved 168 patients with histologically confirmed benign prostatic hyperplasia. Of these patients, 120 underwent transurethral resection of the prostate and 48 – open prostatectomy. The weights of the specimens were compared with the corresponding volumes of the transition zone. Equivalence and correlation between transition zone volume and removed tissue weight were analyzed. Results. The mean (standard deviation, range) transition zone volume was 25.43 mL (±13.19, 5–61.6) in the transurethral resection group and 76.1 mL (±42.97, 13–275.8) in the open operation group. The mean removed tissue weight was 22.9 g (±13.41, 5–66) and 73.96 g (±44.96, 18– 280), respectively, in the transurethral resection and open operation groups. The correlation between removed tissue weight and transition zone volume was stronger in the open operation group than it was in the resection group (r=0.957, P<0.001 vs. r=0.878, P<0.001). There was a significant difference between transition zone volume and resected tissue weight (P=0.001). However, in the open operation group, there was an agreement between transition zone volume and enucleated tissue weight (P=0.263). Conclusions. A significant correlation was detected between removed tissue weight and transition zone volume. There is a significant difference between volume measurement and resected tissue weight while enucleated tissue weight was in agreement with transition zone volume when an open prostatectomy was performed.
Aptamer Display on Diverse DNA Polyhedron Supports
Authors: Shiu Simon Chi-Chin , Fraser Lewis A. , Ding Yifan , Tanner Julian A.
Published: July 2018

DNA aptamers are important tools for molecular recognition, particularly for a new generation of tools for biomedicine based on nucleic acid nanostructures. Here, we investigated the relative abilities of different shapes and sizes of DNA polyhedra to display an aptamer which binds to the malaria biomarker Plasmodium falciparum lactate dehydrogenase (PfLDH). The aptamer was shown to perform an Aptamer-Tethered Enzyme Capture (APTEC) assay with the hypothesis that the display of the aptamer above the surface through the use of a polyhedron may lead to better sensitivity than use of the aptamer alone. We compared different numbers of points of contact, different shapes, including tetrahedron, square, and pentagon-based pyramids, as well as prisms. We also investigated the optimal height of display of the structure. Our results demonstrated that the display of an aptamer on an optimized nanostructure improved sensitivity up to 6-fold relative to the aptamer alone in the APTEC assay. Other important factors included multiple basal points of contact with the surface, a tetrahedron proved superior to the more complex shaped structures, and height above the surface only made minor differences to efficacy. The display of an aptamer on a nanostructure may be beneficial for higher sensitivity aptamer-mediated malaria diagnosis. Aptamer displays using DNA nanostructure polyhedron supports could be a useful approach in a variety of applications.
Expression of Kir2.1 Inward Rectifying Potassium Channels in Optic Nerve Glia: Evidence for Heteromeric Association with Kir4.1 and Kir5.1
Authors: Brasko Csilla , Butt Arthur
Published: July 2018

Inward rectifying potassium (Kir) channels comprise a large family with diverse biophysical properties. A predominant feature of central nervous system (CNS) glia is their expression of Kir4.1, which as homomers are weakly rectifying channels, but form strongly rectifying channels as heteromers with Kir2.1. However, the extent of Kir2.1 expression and their association with Kir4.1 in glia throughout the CNS is unclear. We have examined this in astrocytes and oligodendrocytes of the mouse optic nerve, a typical CNS white matter tract. Western blot and immunocytochemistry demonstrates that optic nerve astrocytes and oligodendrocytes express Kir2.1 and that it co-localises with Kir4.1. Co-immunoprecipitation analysis provided further evidence that Kir2.1 associate with Kir4.1 and, moreover, Kir2.1 expression was significantly reduced in optic nerves and brains from Kir4.1 knock-out mice. In addition, optic nerve glia express Kir5.1, which may associate with Kir2.1 to form silent channels. Immunocytochemical and co-immunoprecipitation analyses indicate that Kir2.1 associate with Kir5.1 in optic nerve glia, but not in the brain. The results provide evidence that astrocytes and oligodendrocytes may express heteromeric Kir2.1/Kir4.1 and Kir2.1/Kir5.1 channels, together with homomeric Kir2.1 and Kir4.1 channels. In astrocytes, expression of multiple Kir channels is the biophysical substrate for the uptake and redistribution of K+ released during neuronal electrical activity known as ‘potassium spatial buffering’. Our findings suggest a similar potential role for the diverse Kir channels expressed by oligodendrocytes, which by way of their myelin sheaths are intimately associated with the sites of action potential propagation and axonal K+ release.
Is Narcissism Sustainable in CEO Leadership of State-Owned Enterprises?
Authors: Kim Bong Hwan
Published: July 2018

The state sector has been an important part of many economies. This study measures the narcissism of the chief executive officers (CEOs) of state-owned enterprises (SOEs) unobtrusively, and examines the effect of narcissism on the performance and accounting earnings management of firms. This study shows that the narcissism of CEOs positively affects the performance of SOEs, and that the positive effect is a result of real management decisions rather than accounting earnings management. It also shows that CEO narcissism does not affect the earnings management of SOEs. However, this relation changes as the tenure of the CEO gets longer. As tenure gets longer, a CEO’s narcissism negatively affects the performance of a SOE, and a CEO with high narcissism is likely to be involved in earnings management to make up for weak performance. This study suggests that narcissism is not a sustainable leadership style. It also suggests that the personal characteristics of executives in public corporations are important in determining the performance of firms. While a longer tenure ensures that a CEO will pursue his/her strategy steadily, the leadership of a narcissistic CEO becomes negative and ineffective as their tenure gets longer. Considering the importance of SOEs in the economy, this is an important policy implication, as the appointment of a CEO and length of tenure are likely to be determined by the government.
THE USE OF FOREIGN WORDS FROM TRANSPORT PUBLICATIONS OF THE END OF THE 19TH CENTURY AND THE FIRST HALF OF THE 20TH CENTURY
Authors: Petrėtienė Angelika
Published: July 2018

The article analyses foreign words (their origin, meaning and equivalents), selected from the transport publications of the end of the 19th century and the first half of the 20th century: the conducted questionnaire method assesses the relevancy of foreign words nowadays, i.e. whether the respondents are aware of the equivalents of foreign words, as well as examines the usage frequency of foreign words. The research defines the respondents’ attitudes towards changing foreign words into their equivalents. It also examines the current usage of the foreign words in different language functional styles. The results of the research are structured and provided in the table and figures.
Política de inovação em nanotecnologia no Brasil: a trajetória dos instrumentos financeiros não reembolsáveis
Authors: Barbosa Tiago Claudino , Bagattolli Carolina , Invernizzi Noela
Published: July 2018

A nanotecnologia (NT) tem sido considerada uma das tecnologias emergentes mais promissoras. Diante disso, o objetivo deste artigo é examinar a trajetória e o volume de recursos da política de inovação em NT considerando os instrumentos de fomento financeiros não reembolsáveis. Em particular, a Subvenção Econômica à Inovação (SEI), da FINEP; o financiamento não reembolsável à associação ICT-empresa (ICT-E), da FINEP; e o programa de Formação de Recursos Humanos em Áreas Estratégicas (RHAE), destinado a pesquisadores em empresas, do CNPQ. A pesquisa é descritiva e sua metodologia consistiu em mapear os projetos aprovados nos editais direcionados à área de NT, assim como os projetos envolvendo NT aprovados em editais não específicos para essa área. A partir deste mapeamento se reconstruiu a linha do tempo dessa política evidenciando, principalmente, a falta de sustentabilidade da estratégia de fomento à nanotecnologia nos três programas, marcada por descontinuidades.
Trabalho material e imaterial e transferência de expertises do trabalhador à maquinaria tecnológica
Authors: Crocco Fábio Luiz Tezini
Published: July 2018

Este artigo analisa imbricações do trabalho material e imaterial e sua relação com os processos de racionalização do trabalho com a finalidade de refletir sobre características e contradições das forças produtivas da atualidade. A discussão da reestruturação produtiva da forma de acumulação flexível é fundamental para esclarecer as novas formas de envolvimento, da “captura” da subjetividade e da transferência de expertises dos trabalhadores para o capital. Esta investigação objetiva examinar criticamente tais processos e desmistificar a suposta aura superior e sublime do trabalho cognitivo e intelectual, principalmente aquele empregado nos setores de tecnologia avançada. Assim, apesar de suas singularidades, o trabalho imaterial apresenta-se como um conjunto de conhecimentos e atividades humanas também reféns do processo de exploração e submetidos à lógica do valor.
Polyura inopinatus Röber, 1940; a remarkable butterfly mystery resolved
Authors: Müller Chris J. , Tennent W. John
Published: July 2018

The most distinctive species of Polyura, P.inopinatus, described from a single specimen said to be from North Sulawesi, Indonesia, has been a great mystery since it was first described by Röber, in 1940. The holotype, originally illustrated in monochrome in the journal Deutsche Entomologische Zeitschrift, Iris, was lost very soon after it was described, almost certainly destroyed during allied bombing of Dresden in the 1940s. No other specimen was known for almost eight decades. We suggest that the type locality (Sulawesi) is incorrect and that the holotype was more likely to have been collected in the Baining Mountains, East New Britain Province, Papua New Guinea. We report the recent discovery of several male P.inopinatus from West New Britain Province, and describe and illustrate specimens. A neotype is designated.
La formation d’ingénieurs par apprentissage : temporalité prescrite et temporalités vécues
Authors: Zaid Abdelkarim , Lebeaume Joël
Published: July 2018

Dans la formation d’ingénieurs par apprentissage, les apprentis ingénieurs (AI) alternent des périodes successives dans des lieux sociaux différents (entreprise et université) a priori distincts, par leurs organisations, leurs acteurs, leurs fonctions économiques, etc. Leur formation professionnalisante postule la reconstruction de cette succession comme un ensemble cohérent d’actions de formation et d’apprentissage. La préoccupation centrale de cet article porte ainsi sur l’investigation didactique de la temporalité prescrite de formation, des temporalités vécues – par les AI et les tuteurs ingénieurs (TI) – et de leur rapport. La temporalité prescrite est reconstruite à partir des documents présentant l’ingénierie pédagogique de la formation en focalisant les contenus, les activités et leur progression au cours d’une séquence de formation. Les temporalités vécues et le rapport entre temporalités prescrite et vécues sont inférés à travers l’analyse thématique et lexicale des discours des AI et des TI recueillis lors d’entretiens semi-directifs. L’analyse de l’ingénierie pédagogique met en évidence un clivage entre temporalité académique et temporalité professionnelle. Ce clivage est actualisé en temporalités vécues : si les TI privilégient l’intégration de l’AI dans le processus de production de l’entreprise, les AI privilégient les acquis du processus de formation exprimés en termes de position et de trajet en entreprise.
La paléogénétique en tant qu’approche archéométrique au cours des 30 dernières années
Authors: Geigl Eva-Maria
Published: July 2018

La paléogénétique, l’étude génétique des organismes
et populations du passé, est devenue possible quand les méthodes de la
biologie moléculaire ont permis l’analyse de l’ADN préservé en état
très dégradé et en très faible quantité dans certains restes
biologiques anciens comme des ossements, des dents, des poils, ou
encore des tissus mous de momies. Ces études ont contribué de manière
très significative à l’archéologie, la paléontologie, la
paléopathologie ou encore la paléoécologie. Plus récemment, le progrès
des méthodes de séquençage de l’ADN a conduit à un nouveau saut
quantique de ce domaine puisque le séquençage de nouvelle génération
rend possible non seulement l’analyse de quelques gènes mais aussi de
génomes entiers des organismes du passé augmentant de plusieurs ordres
de grandeur la quantité d’informations que l’on peut obtenir. Ceci a
permis une révision de notre vision des dernières étapes de
l’évolution humaine et du peuplement de l’Eurasie et de l’Amérique,
mais aussi des processus de domestication des animaux et de certaines
plantes, de l’évolution des populations sauvages animales et végétales
en réponse aux changements climatiques, de l’évolution des pathogènes
responsables d’épidémies, etc. La paléogénomique a ainsi déjà réussi à
révolutionner l’idée que nous nous sommes faite de l’évolution récente
de notre espèce, et on peut légitimement attendre d’elle d’autres très
belles contributions à l’archéologie.
Modelização gráfica da Pré-História do Rio Grande do Sul: Os sítios arqueológicos ameríndios, culturas e temporalidades
Authors: Galhardo Danilo Alexandre , Zago Juliana Aparecida Rocha Luz , Passos Thiago Moraes , Pereira David Lugli Turtela
Published: July 2018

Esse artigo trabalhou com dados de sítios arqueológicos datados de diferentes culturas ameríndias – Tradições Arqueológicas – no estado do Rio Grande do Sul (região Sul do Brasil), levantados a partir de alguns trabalhos arqueológicos sínteses. A sistematização das informações permitiu a confecção de mapas temáticos (produzidos no software ArcGIS versão 10.2) e sistemas baseados no método de modelização gráfica, entendido como um “instrumento de análise regional” (THÉRY, 2004). Desse modo, a coremática sustentada por diferentes estudos arqueológicos desenvolvidos no país, as localizações dos contextos culturais e suas datações absolutas, puderam render hipóteses sobre fluxos e permanências no território.
Faut-il renouveler le regard sur les franges périphériques des villes du Sud ? Le cas des périphéries brésiliennes
Authors: Cerqueira Eugênia Viana
Published: July 2018

Dans la littérature urbaine portant sur les villes brésiliennes, on analyse toujours les marges des agglomérations avec regard binaire, qui oppose le centre et les périphéries. Pourtant, dans les dernières décennies l'on signale un éclatement des modèles classiques des périphéries urbaines, qui va de pair avec une diversification socio-spatiale des marges des villes et un renforcement des dynamiques de ségrégation et de fragmentation. Ces constats appellent à un renouvèlement du regard sur les marges des villes brésiliennes, faisant l’hypothèse que les métropoles des semi-périphéries ont aujourd’hui des trajectoires comparables à celles des villes du Nord. Cet article a pour but de discuter la question de l’étalement urbain dans les métropoles brésiliennes et la construction d’un cadre d’analyse des franges périphériques dans la recherche urbaine, en s’appuyant sur l’étude de la métropole de Belo Horizonte. Cette métropole, la troisième en population du Brésil, offre un terrain d’étude intéressant du fait de son étalement rapide et des nombreuses transformations observées dans ses franges périphériques depuis les deux dernières décennies : de l’expansion du marché immobilier formel, en passant par le desserrement des activités, à l’arrivée des classes moyennes et aisées, les franges périphériques de Belo Horizonte témoignent d’un important processus de diversification qui traduit les dynamiques à l’œuvre dans nombreuses métropoles brésiliennes et d’autres pays du Sud.
C-Idea
Authors: Martin-Nevot Mickaël , Nedjar Sébastien , Lakhal Lotfi , Cicchetti Rosine
Published: July 2018

Discovering trend reversals between two data cubes provides users with novel and interesting knowledge when the real-world context fluctuates: What is new? Which trends appear or emerge? With the concept of emerging cube, the authors capture such trend reversals by enforcing an emergence constraint. In a big data context, trend reversal predictions promote a just-in-time reaction to these strategic phenomena. In addition to prediction, a business intelligence approach aids to understand observed phenomena origins. In order to exhibit them, the proposal must be as fast as possible, without redundancy but with ideally an incremental computation. Moreover, the authors propose an algorithm called C-Idea to compute reduced and lossless representations of the emerging cube by using the concept of cube closure. This approach aims to improve efficiency and scalability while preserving integration capability. The C-Idea algorithm works à la Buc and takes the specific features of emerging cubes into account. The proposals are validated by various experiments for which we measure the size of representations.
Drivers of Urban Development in Terms of Education Based on Digital Technologies
Authors: Potapova Irina , Vasin Sergey Mikhailovich , Gamidullaeva Leyla Ayvarovna , Tolstykh Tatiana , Belyanina Lubov
Published: July 2018

To speed up urban economic development there is a need in radical transformation in the technological fields as well as in the field of mechanisms that encourage the creation and implementation of new technologies. The proposed chapter approach can become a methodological foundation of development and self-development of educational institutions on the principles of continuing education using digital technologies. The chapter deals with the methodology of creating a unified information educational environment, providing the implementation of lifelong learning, the development and implementation of educational models, programs, and media performed with the use of digital technologies. The chapter aims to develop conceptual approach to strategic control of continuing education, innovative development of regulation of educational institutions and to propose practical recommendations based on digital technology.
Model of Benchmarking for Development of Firm's Competitive Advantage to Improve Economic Growth in Cities
Authors: Mkrttchian Vardan , Berezin Andrey , Berezin Artyom Andreevich , Veretekhina Svetlana , Bershadsky Alexander , Potapova Irina
Published: July 2018

The chapter deals with the problems of digital modeling and the study of the interaction of the companies competing within the framework of bench-marking process for working out the strategy of effective increasing competitiveness that is advantageous for the urban economic growth. The companies are considered in the organizational field, representing iterative aggregate system of a big order with a nonlinear feedback where the order is defined by the number of differential equations. The system is described by coupled Van Der Pol differential equations with random right parts and a time lag. The model is built on the example of the market interaction of the two largest retailer networks. The developed model shows the mechanism of competition of the companies' pairs which are suggested to be investigated within the framework of the bench-marking concept.