Processing and Ductile-Brittle Transitions in PM Manganese Steels

YesBrittleness in manganese steels can be associated with processing in a "wet¿ [micro]climate resulting in the formation of continuous oxide networks. The formation of these networks can be prevented by sintering in an atmosphere, also ¿local¿ in a semiclosed container, adhering to the Ellingham-Richardson oxide reduction criteria. When this requirement is satisfied, however, further types of ductile ¿ brittle transitions are observed. Rapid cooling, typically above 40°C/min, produces enough martensite to render Fe-(3-4)Mn-(0·6-0·7)C material macroscopically brittle. Quenched and conventionally tempered structures remain brittle. It is tentatively suggested that segregation of minor alloying/tramp element(s), as in cast materials, is responsible for this temper embrittlement. To overcome it, heat treatment at a temperature no higher than 200°C, recovery/stress relief, is recommended

Anadromous fish as marine nutrient vectors

The tidal freshwater of Virginia supports anadromous herring (Alosa spp.) spawning runs in the spring; however, their importance as nutrient delivery vectors to the freshwater fish food web remains unknown. The stable isotope signatures of fishes from 21 species and four different guilds (predators, carnivores, generalists, and planktivores) were examined in this study to test the hypothesis that marine derived nutrients (MDNs) brought by anadromous fish would be traced into the guilds that incorporated them. Spawning anadromous fish were 13C and 34S-enriched (δ13C and δ34S of approximately 18‰ and 17.7‰, respectively) relative to resident freshwater fish. Of the guilds examined, only predators showed 13C and 34S-enrichment similar to the anadromous fish; however, some generalist catfish also showed enriched signatures. Specific fatty acid δ13C signatures for gizzard shad (Dorosoma cepedianum), blue catfish (Ictalurus furcatus), and alewife (Alosa pseudoharengus), show a 10‰ range among fishes, clearly reflecting isotopically distinct dietary sources. The δ13C and δ34S distribution and range among the freshwater fishes suggest that both autochthonous and allochthonous (terrestrial C3 photosynthetic production and MDN) nutrient sources are important to the tidal freshwater fish community

Transmission Expansion in Argentina 5: The Regional Electricity Forum of Buenos Aires Province

This paper supplements analyses of Argentine transmission expansions at the federal level by looking at experience in Buenos Aires province. A Regional Electricity Forum of distribution companies has drawn up and begun to implement a ten-year transmission expansion plan. Contrary to previous fears, getting agreement between the members on investment and cost sharing has not been unduly problematic. More challenging was getting approval of the provincial government on funding. Deferring tariff reductions and using the revenues for investment facilitated the process, and now some innovative financing arrangements are underway. Again contrary to some previous suggestions, the controversial Area of Influence method was extended rather than replaced. This overcame concerns about free-riding. Progress and investment have been severely curtailed by the economic crisis in 2001 and subsequent federal government policy. The arrangements nonetheless appear to be working well, and to be conducive to more efficient transmission expansion. This confirms that it is practicable and advantageous to allow users rather than the transmission company or the regulator to propose and determine transmission investment, even in a meshed rather than radial system. An appropriate regulatory framework is needed to approve that part of the total budget to paid by distribution business consumers, but this does not require the regulator to lead or monitor the detail of the process

Economic Growth And Child Undernutrition

Sebastian Vollmer and colleagues (April, 2014)1 conclude that “the contribution of economic growth to the reduction in early childhood undernutrition in developing countries is very small, if it exists at all”. Progress will therefore require a shift from “the so-called trickle-down approach of a growth-mediated strategy” to “direct investments in health and nutrition”.

Investigating the influence of music training on verbal memory

Previous research has shown that musical training is associated with enhanced verbal memory. The current study investigated the generality of this association by presenting undergraduates who had received musical training (n = 20) and undergraduates with no formal music training (n = 20) with four types of word list; high visual imagery, high auditory imagery, high tactile imagery, and abstract. Those who had received music training showed enhanced memory for all word lists, suggesting that music training leads to a general enhancement in verbal memory that is not restricted to specific types of words (e.g., those invoking auditory imagery). The findings support previous research in showing that music training enhances cognitive skills beyond those that are specific to the domain of music. The possible cognitive and neural factors underpinning this effect are discussed

Examining the Scope of Channel Expansion: A Test of Channel Expansion Theory with New and Traditional Communication Media

This article draws on channel expansion theory to explore the selection and use of communication media by organizational members. Channel expansion theory scholars posit that media richness perceptions are dependent on experiences with communication partners, the message topic, and the communication media utilized. This study tests channel expansion theory in the context of new and traditional communication media. Respondents (N = 269) completed questionnaires regarding their use and perceptions of face-to-face, telephone, e-mail, or instant-messaging interactions. Results indicate that experience with channel, topic, partner, and social influence are all significant predictors of richness perceptions, when controlling for age and media characteristics. Findings also suggest that the richness of a medium is not fixed and may be shaped by interpersonal factors, including one’s relevant experiences

Story contexts increase susceptibility to the DRM illusion in 5-year-olds.

False recognition in children aged 5, 8, and 11 years was investigated using the standard version of the Deese-Roediger-McDermott (DRM) procedure and an alternative version in which the DRM stimuli were embedded in stories designed to emphasize their overall theme. Relative to the 8- and 11-year-olds, the 5-year-olds falsely recognized fewer critical lures when the DRM stimuli were presented in lists, but falsely recognized more critical lures when the stimuli were presented in stories. Levels of false recognition in the 8- and 11-year-olds were not affected by study format. We argue that the story context enhanced the ability of the 5-year-olds to make inferences based on the theme of the DRM stimuli. The 5-year-olds then showed higher levels of false recognition than the older children owing to their inability to reject lure words consistent with the stories

Ion implantation damage of silicon as observed by optical reflection spectroscopy in the 1 to 6 eV region

Optical reflection spectra of crystalline, sputtered, and ion implanted silicon specimens are presented. Characteristic aspects of the spectra of ion implanted specimens are related to lattice damage