Applications of Electron Backscatter Diffraction (EBSD) in Archaeology

Electron backscattered diffraction (EBSD) has been used to study samples of archaeological gold, silver, copper and bronze prepared using simple metallographic etches. EBSD maps of orientation and local misorientation revealed the metals’ microstructures and deformation substructures, and from this, combined in some cases with information on the crystallographic texture (also determined by EBSD), the methods of manufacture and working of the artefacts were determined. EBSD was also used to examine discontinuous precipitation at grain boundaries in a silver alloy at a high resolution

Using size distributions for determining growth mechanisms of grain boundary precipitates

In the past various single parameters such as the mean, mode or maximum of the precipitate size distribution have been used in experiments to determine growth mechanisms. In the present study the development with aging time of the size and shape distributions of bcc precipitates at grain boundaries in an fcc material (Co-20Fe at 1003oK) have been compared with possible theoretical models to determine the rate controlling process. The growth of these precipitates is initially well described by the grain boundary dependent collector plate mechanism of Brailsford and Aaron. As the precipitates grow low energy facets are formed which can move only by the propagation of ledges and growth becomes interface controlled. The precipitates’ diffusion fields soon overlap and coarsening occurs with interface control. The results demonstrate that this would not have been revealed using simpler measures of precipitate size

Boundary selectivity of crack paths in corrosion fatigue of stainless steel

Stress corrosion and corrosion fatigue cracks are frequently very branched and there have been extensive attempts to define the characteristics of crack-stopping features. EBSD has been used to examine the full length (~8mm) of a corrosion fatigue crack in stainless steel. The grain boundary character distribution of the cracked boundaries is compared to that of the rest of the material and observations presented on the effect of grain boundary character on the choice of crack path at grain boundary junctions of different configurations and orientations with restect to the principle stres

Inhibition of NO-synthase and degranulation of rat omental mast cells in vitro

Mast cell amines, platelet-activating factor (PAF), thromboxanes and leukotrienes have been shown to be released during nitric oxide-synthase inhibition in the rat intestine. Mast cells in rat isolated omentum (OMCs) or isolated from the rat peritoneal cavity (PMCs) have been used here to investigate the relationship(s) between these agents. N-nitro-L-arginine methyl ester (L-NAME, 100 μM) caused some degranulation of OMCs, but no enhancement of histamine release from PMCs. PAF (5 μM) and U46619 (1 μM) degranulated OMCs and enhanced histamine release from PMCs. Pre-treatment of the omentum with BN52021 (10 μM) inhibited degranulation of OMCs in response to L-NAME, PAF or U46619. Pretreatment with 1-benzylimidazole (5 or 50 μM) inhibited the effect of L-NAME but not that of PAF. Indomethacin (1 μM) or sodium nitroprusside (10 μM) also inhibited the effects of L-NAME, but nordihydroguaiaretic acid (30 μM) did not. In PMCs BN52021 inhibited PAF-induced, but not U46619-induced, release of histamine. These results suggest that inhibition of nitric oxidesynthase in the omentum by L-NAME allows thromboxanes to release PAF, which in turn degranulates and releases histamine from OMCs

Possible bi-directional link between ETA receptors and protein kinase C in rat blood vessels

Possible links have been investigated between activation of protein kinase C (PKC) and endothelin (ET) production by small blood vessels. Perfusion pressures were recorded from rat isolated mesenteric artery, with or without the small intestine attached, before and after addition to the perfusate of either ET-1, ET-3 or the PKC activator 12-deoxyphorbol 13-phenylacetate (DOPPA). Rises in perfusion pressure in response to ET-1 (10−8 M)or DOPPA (10−6 M) were reduced significantly by pre-treatment with either the ETA receptor antagonist PD151242 (10−6 M) or the PKC inhibitor Ro 31-8220 (10−6 M). ET-3 (10−8 M) had a significant, albeit small, effect only when the gut was still attached to the mesentery. Inthis latter preparation ET-1 and DOPPA increased the permeability of villi microvessels to colloidal carbon in the perfusate. This effect of DOPPA was reduced by pre-treatment with either PD151242 or Ro 31-8220, but the effects of ET-1 were reduced significantly only by Ro 31-8220. ET-3 (10−8 M) was without effect. The results suggest a possible bi-directional link between ETA receptors and PKC in the intestinal vasculature

Rate of perfusion modulates colloidal carbon leakage from rat intestinal microvessels in vitro

In order to investigate the effects of varying the rate of flow on endothelial integrity the rat isolated small intestinal vasculature was perfused at 1, 5, 10 or 20 ml/min with a gelatin-containing physiological salt solution (GPSS), followed by an injection of colloidal carbon suspension (CC). Significantly greater microvascular CC leakage occurred at 1 or 5 ml/min than at 10 or 20 ml/ mitt. CC leakage at the two slower rates of flow was reduced by adding red blood cells to the GPSS, suggesting that the microvascular endothelium became hypoxic when perfused with GPSS at 1 or 5 ml/min. After perfusion at 20 ml/min with GPSS containing resiniferatoxin (1 μM) or 5-hydroxytryptamine (100 μM), CC leakage was significantly lower than after similar perfusion at 10 ml/min. Two nitric oxide (NO) synthesis blockers, N-nitro-L-arginine methyl ester (L-NAME, 100 μM) and methylene blue (20 μM), and an NO scavenger CPTIO (100 μM) each increased CC leakage. This suggests that NO was being produced at perfusion rates of 10 or 20 ml/min. Sodium nitroprusside (10 μM), 8-bromo-cGMP (100 μM) and BN52021 (10 μM) each significantly reduced CC leakage in the presence of L-NAME

Rat intestinal mast cell amines are released during nitric oxide synthase inhibition in vitro

Inhibition of nitric oxide synthase increases microvascular permeability in rat small intestinal villi. To determine the mechanism(s) whereby this occurs we have perfused the vasculature of rat isolated small intestines with a gelatin-containing physiological salt solution. Inclusion of N-nitro-L-argintne methyl ester (L-NAME, 100 μM) or indomethacin (1 μM) in the perfusate increased leakage of injected colloidal carbon into microvessel walls. Pre-treatment with sodium nitroprusside (10 μM) significantly reduced the effects of both L-NAME and indomethacin, whereas carbacyclin (1 μM) only reduced the effects of indomethacin. PD151242 (1 μM) showed some antagonism towards the effects of L-NAME, but nordihydroguaiaretic acid (3 μM) was inactive. Pre-tment with cyproheptadine (10 μM) reduced the effects of both L-NAME and indomethacin, and also significantly reduced background (control) colloidal carbon leakage. Small intestines from polymixin B-treated rats showed significantly reduced colloidal carbon leakage in response to L-NAME. This suggests that the leakage-enhancing effects of both L-NAME and indomethacin in this preparation may be mediated by mast cell-derived amines

Microstructures of cast silver-copper alloy archaeological artefacts

Cast silver-copper alloys objects form a significant part of the archaeological record from the first millenium BC onwards. Although age hardening of annealed and quenched material has been well studied there has been little study of cast microstructures. This work used a combination of scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and optical microscopy (OM) to explore the range of microstructures in archaeological cast silver and compare them with those in modern cast silver. Modern cast silver showed extensive fine scale precipitation of copper within the grains which was unconnected to the copper-rich phase of the primary eutectic. Ancient cast objects displayed a wide range of microstructures, some very similar to the modern cast silver but some quite different. EBSD allowed interpretation of the microstructure close to some grain boundaries whose detail was obscured by the cast structure in OM and SEM images. Orientation images showed fine-scale interpenetration of the adjoining grains suggesting cellular growth, suggesting that over archaeological time boundary modification may take place in cast as well as wrought and annealed structures

A canonical form of arithmetic and conditional expressions

This paper contributes to code clone detection by providing an algorithm that calculates canonical forms of arithmetic and conditional expressions. An experimental evaluation shows the relevance of such expressions in real code. The proposed normalization can be used in addition to dataflow normalizations

Women and work in the Fourth Industrial Revolution: An exploratory study of women's experience in IT Jobs

Information and Communication Technology (ICT) is leading the discontinuous change in every sphere of our lives, from the Internet of everything to the Internet of all, and from Artificial Intelligence and Robotics to Human Augmentation. As nations experience shifting sources of competitiveness and a “hollowing out” effect, existing competencies get destroyed and the need for new competencies arises. On one hand, there is an increasing requirement for a workforce with high technical skills and on the other hand there is a shortage of human capital that can meet this need (Choi 2017). Information Technology (IT) is one of the key sectors experiencing this phenomenon. The high gender gap - a constant 72 percent which is estimated to continue in the future – further compounds the problem. IT is seen as a male dominated occupation, as indicated, for example, by the 78 percent:22 percent male-to-female ratio of Artificial Intelligence professionals globally (World Economic Forum 2018). Even amongst the women who do work in the IT profession, studies report a “leaky pipeline” with women moving away from their IT jobs during their career (Vitores & Gil-Juárez 2016). There is an urgent need for understanding the phenomenon of gender representation in the era of the Fourth Industrial Revolution. To this end, the present study explores the experiences of women working in IT departments and organizations in Dubai, their motivations, challenges, coping strategies and organizational support systems. These women have been chosen for the study to compare the experiences of IT versus non-IT women professionals working in the IT field. Neo-classical and human capital theories highlight women’s lower levels of education and workplace experience due to childcare responsibilities. Feminist theories argue that the underlying reason lies in the patriarchal attitudes and structures that perpetuate male domination in society, which extend to the workplace. Gender studies predominantly report challenges and negative experiences that include prejudice, hostility, inequality, stereotyping etc., all of which originate from social conditioning. A gender-neutral axiological stance has been adopted for this study which broadens the understanding of womens’ experiences - both positive and negative - the sources of the challenges as well as the support from the opposite gender as well as same-gender peers, superiors and subordinates; and the elements of social conditioning that aided and those that exacerbated their experiences. The study was undertaken from a yin-and-yang positionality rather than using a gender hierarchy and hence treats both genders as complementing each other. The objective is to help address the service management imperatives of developing an enabling work culture, harnessing the potential of employees and developing a sustainable pipeline of competent professionals, which essentially involves addressing the challenges faced by women and mitigating barriers to their empowered contribution. The approach adopted was a relativist ontological approach that aimed to understand the reality as perceived by women working in IT departments/companies based on their social interactions and experiences. To address the challenges, effective service management strategies must be based on an understanding of women’s subjective reality, a qualitative study marked the first phase of the study. Keywords: Gender gap in services, IT industry, IR4, Experiences, support strategies, coping mechanisms, gender-neutral approac