Primary intestinal lymphangiectasia (Waldmann's disease)

Primary intestinal lymphangiectasia (PIL) is a rare disorder characterized by dilated intestinal lacteals resulting in lymph leakage into the small bowel lumen and responsible for protein-losing enteropathy leading to lymphopenia, hypoalbuminemia and hypogammaglobulinemia. PIL is generally diagnosed before 3 years of age but may be diagnosed in older patients. Prevalence is unknown. The main symptom is predominantly bilateral lower limb edema. Edema may be moderate to severe with anasarca and includes pleural effusion, pericarditis or chylous ascites. Fatigue, abdominal pain, weight loss, inability to gain weight, moderate diarrhea or fat-soluble vitamin deficiencies due to malabsorption may also be present. In some patients, limb lymphedema is associated with PIL and is difficult to distinguish lymphedema from edema. Exsudative enteropathy is confirmed by the elevated 24-h stool α1-antitrypsin clearance. Etiology remains unknown. Very rare familial cases of PIL have been reported. Diagnosis is confirmed by endoscopic observation of intestinal lymphangiectasia with the corresponding histology of intestinal biopsy specimens. Videocapsule endoscopy may be useful when endoscopic findings are not contributive. Differential diagnosis includes constrictive pericarditis, intestinal lymphoma, Whipple's disease, Crohn's disease, intestinal tuberculosis, sarcoidosis or systemic sclerosis. Several B-cell lymphomas confined to the gastrointestinal tract (stomach, jejunum, midgut, ileum) or with extra-intestinal localizations were reported in PIL patients. A low-fat diet associated with medium-chain triglyceride supplementation is the cornerstone of PIL medical management. The absence of fat in the diet prevents chyle engorgement of the intestinal lymphatic vessels thereby preventing their rupture with its ensuing lymph loss. Medium-chain triglycerides are absorbed directly into the portal venous circulation and avoid lacteal overloading. Other inconsistently effective treatments have been proposed for PIL patients, such as antiplasmin, octreotide or corticosteroids. Surgical small-bowel resection is useful in the rare cases with segmental and localized intestinal lymphangiectasia. The need for dietary control appears to be permanent, because clinical and biochemical findings reappear after low-fat diet withdrawal. PIL outcome may be severe even life-threatening when malignant complications or serous effusion(s) occur

International entrepreneurship in SMEs: a study of influencing factors in the textile industry

The final publication is available at Springer via http://dx.doi.org/10.1007/s11365-012-0242-3International entrepreneurship is an incipient research area with a rapidly increasing body of knowledge and contributions. An important part of this literature has focused on the analysis of the contributing factors to IE development. From these studies, this work attempts to analyse and validate through an integrative model the effect on this construct in SME of some of the main factors proposed by the literature such as Skills and Competences, Attitude and Proactiveness, Creativity and Innovation, Networking, Employees and Activity. To proceed with this aim, we conducted an empirical research focused on 174 textile SME in Spain. The results obtained confirm a positive relationship between the studied factors and the IE development. 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Comparison and combination of two NDT methods with implications for compressive strength evaluation of selected masonry and building stones

The classic Schmidt hammer (SH) and the Equotip hardness tester (EHT) are the widely used nondestructive (NDT) instruments for measuring surface dynamic hardness (rebound hardness) of materials. In previous studies, both instruments have been used individually to establish empirical models for uniaxial compressive strength (UCS) evaluation of rock materials. However, no specific research seems to have been undertaken to investigate their relative UCS prediction effectiveness when performed on the same rock samples. In this study, we evaluated the relative UCS prediction performance of these two NDT instruments by performing laboratory tests on core specimens of some selected rock materials used as masonry and building stones. The correlations of Schmidt hammer rebound hardness (SHR) and Equotip hardness (HLB) to UCS were determined by using regression analyses and test statistics. Also, the variability of each test method was evaluated by employing variance analyses. The results indicated that the established UCS prediction models for both NDT methods were significant in the statistical sense (p value <0.05), with the EHT method showing somewhat better prediction accuracy (R-2 = 0.87; accuracy ratio = 0.60) compared to the SH method (R-2 = 0.84; accuracy ratio = 0.78). Data scatter graphs showed increasing standard deviation in UCS for increasing rebound indices. An average conversion factor (k) of 15.7 was derived in the zero-intercept regression model HLB = k . SHR, which may be used in practice as a guide to translate the measured hardness values from one instrument to another. For improved UCS prediction accuracy, an attempt was made to evaluate the potential use of a newly proposed combined NDT method involving the simultaneous use of SH and EHT test results. With this kind of approach, a relatively better prediction accuracy was achieved (R-2 = 0.89; accuracy ratio = 0.52) compared to the use of the SH and EHT methods individually

Diamond Tool Specific Wear Rate Assessment in Granite Machining by Means of Knoop Micro-Hardness and Process Parameters

The present study was undertaken to investigate the potential usability of Knoop micro-hardness, both as a single parameter and in combination with operational parameters, for sawblade specific wear rate (SWR) assessment in the machining of ornamental granites. The sawing tests were performed on different commercially available granite varieties by using a fully instrumented side-cutting machine. During the sawing tests, two fundamental productivity parameters, namely the workpiece feed rate and cutting depth, were varied at different levels. The good correspondence observed between the measured Knoop hardness and SWR values for different operational conditions indicates that it has the potential to be used as a rock material property that can be employed in preliminary wear estimations of diamond sawblades. Also, a multiple regression model directed to SWR prediction was developed which takes into account the Knoop hardness, cutting depth and workpiece feed rate. The relative contribution of each independent variable in the prediction of SWR was determined by using test statistics. The prediction accuracy of the established model was checked against new observations. The strong prediction performance of the model suggests that its framework may be applied to other granites and operational conditions for quantifying or differentiating the relative wear performance of diamond sawblades

Rock cuttability assessment using the concept of hybrid dynamic hardness (HDH)

Hybrid dynamic hardness (HDH) is an indentation-based rock hardness concept which is a formulated combination of the surface rebound hardness and the deformation ratio of a given rock material. This new concept was recently put forward by one of the present authors and was successfully applied to estimate the uniaxial compressive strength of carbonate rocks. So far, there has been no application of this hardness concept to rock cuttability assessment. Considering this fact, the present work was performed to examine the tenability of the HDH concept in rock cuttability assessment, in relation to the prediction of rock cutting specific energy, cutting forces, and the field cutting performances of some mechanical excavators. To achieve these goals, the authors have statistically evaluated a wide variety of laboratory and field data previously reported in the literature. Results of the statistical analyses indicate that the HDH testing procedure employed in the present work has the potential to be used as an index rock material property that can be employed in preliminary estimations of specific energy, cutting force, and normal force for a wide range of rocks under different operational conditions involving conical cutters (tip angle 80A degrees, attack angle 55A degrees, relieved cutting mode at optimum spacing to depth of cut ratio) and chisel cutters (rake angle -5A degrees, clearance angle 5A degrees, tip width 12.7 mm, cutting depths 1, 2, and 3 mm, unrelieved cutting mode). The close correspondence also observed between the calculated HDH values and the field-measured net cutting performance values of a roadheader and some chainsaw machines provide further evidence of the usability of this concept for rock cuttability assessment purposes

Correlative relations between three-body abrasion wear resistance and petrographic properties of selected granites used as floor coverings

Stone tiles used as flooring materials in buildings are subject to three-body abrasion wear due to pedestrian traffic. Hence, wear resistance characterization of stone materials is an important issue in civil engineering projects for appropriate selection and design of floor coverings. The objective of the present work was to identify the most influential quantitative petrographic properties of granites affecting their wear resistance values determined by the Wide Wheel Abrasion (WWA) test. For this purpose, petrographic analyzes and abrasion wear tests were performed on selected granites showing variations in their mineral modal composition, grain size distribution, hardness, porosity and density values. Results of the statistical analyzes indicate that the abrasion resistance of the tested granites is more influenced by modal mineral composition than the grain size. The overall Rosiwal hardness (HR) and the presently proposed petrographic index 'quartz to all cleavable minerals ratio' (QJCLV), both have the potential to be employed as effective tools for obtaining preliminary estimations of abrasion resistance in similar granite types. Micro-hardness determined by the Knoop indenter did not prove to be a reliable indicator of granite wear resistance, which is in disagreement with the Archard's classical wear law formulated for relatively homogeneous and isotropic materials. (C) 2016 Elsevier B.V. All rights reserved

Comparison of averaging procedures for point load testing of rock

This paper presents the experimental results of a laboratory point load testing program carried out to analyze the effect of two different point load mean value calculation procedures on the prediction accuracy of uniaxial compressive strength of rocks. Apart from the calculation procedure corresponding to the one suggested by ASTM and ISRM, a second calculation procedure involving the ordinary arithmetic mean value was used in the analyses. Axial point load tests were conducted on a total of 19 rocks having two different thickness-to-diameter ratios. Finally, the results of the point load tests were correlated with those of the standard uniaxial compressive strength tests, and some test statistics were employed to determine the relative effectiveness of the considered calculation procedures. Valid for axial testing method and the tested rock types, it was Concluded that the suggested mean value calculation procedure by the ASTM and ISRM has no significant advantage compared with the traditional statistical procedure that involves ordinary arithmetic mean

Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

WOS: 000300169000009In Europe, the Wide Wheel abrasion (WWA) test and the Bohme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation (R-2 = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly (R-2 = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity >= 1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multidirectional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse-grained granitic rocks having cleavable minerals such as plagioclase and orthoclase feldspars

Abrasion wear characterization of some selected stone flooring materials with respect to contact load

Abrasion of stone flooring materials under the influence of foot traffic is mainly a function of the load exerted on them by fine solid particles. This paper presents a study of the abrasion behavior of some natural stone flooring materials when subjected to wear under varying contact loads. Abrasion wear tests were performed on a Bohme apparatus which is widely used in the construction industry for determining flooring suitability of stone tiles. Contact loads ranging from 100 to 500 N were applied for each tested stone material, while keeping the other operational parameters constant. In the case of carbonate stone materials, abrasion wear rate was found to be linearly proportional to the applied load. The granites, however, exhibited a non-linear abrasion wear behavior, not conforming to Archard's well-known classical wear law. It was also observed that, in some cases, changes in the applied load could be an influencing factor in the ranking of flooring materials with respect to abrasion wear rate. (C) 2012 Elsevier Ltd. All rights reserved

Relative brittleness characterization of some selected granitic building stones: Influence of mineral grain size

Being crystalline materials, brittleness may be an important issue for granitic rocks, especially when they are subject to certain loading conditions. Therefore, in practice, more specifically in their usage as a natural building stone, there is a need for their brittleness characterization. This paper reports a study carried out on some selected granitic rock types in order to determine their relative brittleness index values and relate it to their mineral grain size. For this purpose, three different types of granitic rocks similar in mineral composition, but diverse in grain sizes were selected for the execution of the study. The relative brittleness index values of the studied rock types were determined from the size effect method by using the point load test apparatus. Based on the results of this investigation it is was concluded that, rather than the proportions of the rock forming minerals such as quartz and feldspars, the grain size of feldspars could be the dominant parameter affecting relative brittleness values of the tested rocks. (C) 2007 Elsevier Ltd. All rights reserved