12,714 research outputs found
Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2
Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy
Respiratory Syncytial Virus
RSV infection has an estimated global incidence of 33 million cases in children <5 years of age, with 10% requiring hospital admission and up to 199 000 dying of the disease. There is growing evidence that severe infantile RSV bronchiolitis, a condition characterised by an inflammatory reaction to the virus, is associated with later childhood wheeze in some vulnerable children; however, a direct causal relationship with asthma has not yet been established. RSV infection is also increasingly recognised as a cause of morbidity and mortality in those with underlying airway disease, the immunocompromised and frail elderly persons. Novel molecular-based diagnostic tools are becoming established, but treatment remains largely supportive, with palivizumab the only licensed agent currently available for passive prophylaxis of selected pre-term infants. While effective treatments remain elusive, there is optimism about the testing of novel antiviral drugs and the development of vaccines that may induce long-lasting immunity without the risk of disease augmentation
Urban heritage conservation and rapid urbanization : insights from Surat, India
Currently, heritage is challenged in the Indian city of Surat due to diverse pressures, including rapid urbanization, increasing housing demand, and socio‐cultural and climate changes. Where rapid demographic growth of urban areas is happening, heritage is disappearing at an alarming rate. Despite some efforts from the local government, urban cultural heritage is being neglected and historic buildings keep being replaced by ordinary concrete buildings at a worryingly rapid pace. Discussions of challenges and issues of Surat’s urban area is supported by a qualitative dataset, including in‐depth semi‐structured interviews and focus groups with local policy makers, planners, and heritage experts, triangulated by observation and a photo‐survey of two historic areas. Findings from this study reveal a myriad of challenges such as: inadequacy of urban conservation management policies and processes focused on heritage, absence of skills, training, and resources amongst decision makers and persistent conflict and competition between heritage conservation needs and developers’ interests. Furthermore, the values and significance of Surat’s tangible and intangible heritage is not fully recognized by its citizens and heritage stakeholders. A crucial opportunity exists for Surat to maximize the potential of heritage and reinforce urban identity for its present and future generations. Surat’s context is representative of general trends and conservation challenges and therefore recommendations developed in this study hold the potential to offer interesting insights to the wider planners and conservationists’ international community. This paper recommends thoughtful integration of sustainable heritage urban conservation into local urban development frameworks and the establishment of approaches that recognize the plurality of heritage values
A Tale of Two Data-Intensive Paradigms: Applications, Abstractions, and Architectures
Scientific problems that depend on processing large amounts of data require
overcoming challenges in multiple areas: managing large-scale data
distribution, co-placement and scheduling of data with compute resources, and
storing and transferring large volumes of data. We analyze the ecosystems of
the two prominent paradigms for data-intensive applications, hereafter referred
to as the high-performance computing and the Apache-Hadoop paradigm. We propose
a basis, common terminology and functional factors upon which to analyze the
two approaches of both paradigms. We discuss the concept of "Big Data Ogres"
and their facets as means of understanding and characterizing the most common
application workloads found across the two paradigms. We then discuss the
salient features of the two paradigms, and compare and contrast the two
approaches. Specifically, we examine common implementation/approaches of these
paradigms, shed light upon the reasons for their current "architecture" and
discuss some typical workloads that utilize them. In spite of the significant
software distinctions, we believe there is architectural similarity. We discuss
the potential integration of different implementations, across the different
levels and components. Our comparison progresses from a fully qualitative
examination of the two paradigms, to a semi-quantitative methodology. We use a
simple and broadly used Ogre (K-means clustering), characterize its performance
on a range of representative platforms, covering several implementations from
both paradigms. Our experiments provide an insight into the relative strengths
of the two paradigms. We propose that the set of Ogres will serve as a
benchmark to evaluate the two paradigms along different dimensions.Comment: 8 pages, 2 figure
Do CIOs Matter? Assessing the Value of CIO Presence in Top Management Teams
Though the importance of Chief Information Officers (CIOs) is well recognized in academic literature, concerns have often been expressed about the status of CIOs and their waning influence. In fact, not all firms choose to have Chief Information Officers (CIOs)as a part of their top management teams. This research investigates whether CIO presence/absence in top management teams affect firm performance. We assembled a multi-industry dataset of 205 firms that included CIOs in their TMTs and assessed their financial and market performance over a three year period (2002-2004). We found firms that included CIOs in their top management teams to have significantly better financial performance than their peer firms who did not. The results and their implications are discussed. This study provides an initial step towards understanding the empirical linkages between IT leadership and firm performance
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