805 research outputs found
Determination of critical cooling rates in metallic glass forming alloy libraries through laser spike annealing
No full textThe glass forming ability (GFA) of metallic glasses (MGs) is quantified by the critical cooling rate (RC). Despite its key role in MG research, experimental challenges have limited measured RC to a minute fraction of known glass formers. We present a combinatorial approach to directly measure RC for large compositional ranges. This is realized through the use of compositionally-graded alloy libraries, which were photo-thermally heated by scanning laser spike annealing of an absorbing layer, then melted and cooled at various rates. Coupled with X-ray diffraction mapping, GFA is determined from direct RC measurements. We exemplify this technique for the Au-Cu-Si system, where we identify Au56Cu27Si17 as the alloy with the highest GFA. In general, this method enables measurements of RC over large compositional areas, which is powerful for materials discovery and, when correlating with chemistry and other properties, for a deeper understanding of MG formation.Peer reviewe
Obtaining Thickness-Limited Electrospray Deposition for 3D coating
No full textThe electrospray process utilizes the balance of electrostatic forces and surface tension within a charged spray to produce charged microdroplets with a narrow dispersion in size. In electrospray deposition, each droplet carries a small quantity of suspended material to a target substrate. Past electrospray deposition results fall into two major categories: (1) continuous spray of films onto conducting substrates and (2) spray of isolated droplets onto insulating substrates. A cross-over regime, or a self-limited spray, has only been limitedly observed in the spray of insulating materials onto conductive substrates. In such sprays, a limiting thickness emerges where the accumulation of charge repels further spray. In this study, we examined the parametric spray of several glassy polymers to both categorize past electrospray deposition results and uncover the critical parameters for thickness-limited sprays. The key parameters for determining the limiting thickness were (1) field strength and (2) the spray temperature, related to (1) the necessary repulsive field and (2) the ability for the deposited materials to swell in the carrier solvent vapor and redistribute charge. These control mechanisms can be applied to the uniform or controllably varied microscale coating of complex 3D objects.Peer reviewe
Intelligibility of high-pitched vowel sounds in the singing and speaking of a female Cantonese Opera singer
No full textThe question whether or not vowel quality can be maintained at F0 of the sounds exceeding statistical F1 of „normal“ speech is still a matter of debate. The present study investigates the perception of long Cantonese vowels /i, y, œ, a, ɔ, u/, spoken and sung in (C)V and (C)V:S context by a well-known female Cantonese Opera singer in the range of F0 of c. 560–860Hz. 172 high-pitched syllables or isolated vowel sounds were selected and extracted from a live recording. Corresponding vowel perception was tested in a listening test performed by 26 students of linguistics. All six vowels proved to be identifiable > 80% up to F0 of c. 700Hz, and sounds of /i, a, ɔ, u/ proved to be identifiable > 80% up to a range of F0 of c. 820–860Hz. Confusion matrices are provided in the present paper and spectral illustrations of all sounds are presented at http://is2014.phones-and-phonemes.org
Pragmatic approach to nutrition in the ICU: Expert opinion regarding which calorie protein target
No full textBACKGROUND & AIMS:Since the publications of the ESPEN guidelines on enteral and parenteral nutrition in ICU, numerous studies have added information to assist the nutritional management of critically ill patients regarding the recognition of the right population to feed, the energy-protein targeting, the route and the timing to start.
METHODS: We reviewed and discussed the literature related to nutrition in the ICU from 2006 until October 2013.
RESULTS: To identify safe, minimal and maximal amounts for the different nutrients and at the different stages of the acute illness is necessary. These amounts might be specific for different phases in the time course of the patient's illness. The best approach is to target the energy goal defined by indirect calorimetry. High protein intake (1.5 g/kg/d) is recommended during the early phase of the ICU stay, regardless of the simultaneous calorie intake. This recommendation can reduce catabolism. Later on, high protein intake remains recommended, likely combined with a sufficient amount of energy to avoid proteolysis.
CONCLUSIONS: Pragmatic recommendations are proposed to practically optimize nutritional therapy based on recent publications. However, on some issues, there is insufficient evidence to make expert recommendations
The key role of nitric oxide in hypoxia: hypoxic vasodilation and energy supply-demand matching
No full textSignificance: a mismatch between energy supply and demand induces tissue hypoxia with the potential to cause cell death and organ failure. Whenever arterial oxygen concentration is reduced, increases in blood flow - 'hypoxic vasodilation' - occur in an attempt to restore oxygen supply. Nitric oxide is a major signalling and effector molecule mediating the body's response to hypoxia, given its unique characteristics of vasodilation (improving blood flow and oxygen supply) and modulation of energetic metabolism (reducing oxygen consumption and promoting utilization of alternative pathways). Recent advances: this review covers the role of oxygen in metabolism and responses to hypoxia, the hemodynamic and metabolic effects of nitric oxide, and mechanisms underlying the involvement of nitric oxide in hypoxic vasodilation. Recent insights into nitric oxide metabolism will be discussed, including the role for dietary intake of nitrate, endogenous nitrite reductases, and release of nitric oxide from storage pools. The processes through which nitric oxide levels are elevated during hypoxia are presented, namely (i) increased synthesis from nitric oxide synthases, increased reduction of nitrite to nitric oxide by heme- or pterin-based enzymes and increased release from nitric oxide stores, and (ii) reduced deactivation by mitochondrial cytochrome c oxidase. Critical issues: several reviews covered modulation of energetic metabolism by nitric oxide, while here we highlight the crucial role NO plays in achieving cardiocirculatory homeostasis during acute hypoxia through both vasodilation and metabolic suppression Future directions: we identify a key position for nitric oxide in the body's adaptation to an acute energy supply-demand mismatc
26th Annual African American Living Legends Series - Etta James, Clinton Tatum, Jr., and [unknown]
No full textSinger, author, and event honoree Etta James (seated) with Deputy Supervisor Clinton Tatum, Jr. (right) and [unknown] (rear)
26th Annual African American Living Legends Series - Honoring Etta James and Essie Mae Washington-Williams
No full textSinger, author, and event honoree Etta James (center) stands to accept the award as other dignitaries and the audience applauds
"Death, Buddhism, and Existentialism in the Songs of Tr???nh C??ng S??n"
No full textVarious explanations have been offered for the extraordinary popularity of the composer and singer Tr???nh C??ng S??n: his poetic lyrics, his avoidance of the clich??s of prewar music, his antiwar themes, his ability to choose talented female singers, and the like. But little has been said about the Buddhist themes in his songs, perhaps because Vietnamese scholars take them for granted. This article points out these themes and argues that they help explain the Tr???nh C??ng S??n phenomenon. It also discusses European existentialism, which the author argues fascinated Tr???nh C??ng S??n but was ultimately not a major influence on his work
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Learning, Remembering, and Relating Sequences in the Hippocampus
No full textAs a crossroads between sensory inputs and long term memories, the hippocampus turns a plethora of information into concise episodes for us to remember. The hippocampus can employ different strategies to achieve this transformation. By selecting only notable experiences to transfer to long term memory storage, we can remember important experiences while forgetting the mundane. By encoding common principles among several experiences, we can remember appropriate general responses and predict future similar experiences. We considered ways the hippocampus might achieve these two possibilities by examining hippocampal activity while rats executed sequences for rewards. Given that we must remember the experiences that lead to reward in order to exploit these rewards in the future, we asked if memory processes are enhanced by reward. In particular we examined hippocampal sharp wave-ripples (SWRs) because reactivation of previous experiences during SWRs is thought to be essential for event memory storage. We found that SWR activity increases when animals receive reward. This reward related SWR activity is further enhanced when animals have to learn new path-reward associations. Additionally, SWR activity reactivates neural patterns that occur as animals run to or from the reward. Because SWRs are implicated in memory consolidation, this enhanced SWR reactivation could be a mechanism to preferentially remember experiences associated with reward. Furthermore, when navigating environments with many repeated elements, generalizing across elements can be advantageous to efficiently encode appropriate responses. Simultaneously, each element must also be differentiated from the others. To study this, we then examined hippocampal activity as animals traversed environments with many repeated elements and had to distinguish between these elements to receive reward. We found that some hippocampal cells fire very similarly on multiple repeated elements, while other cells encode the elements differently. Cells that generalize across similar elements have correlated moment to moment activity, suggesting that they are part of functional ensembles. Furthermore, this generalizing / path equivalent activity increases as animals learn new relationships between repeated elements. This generalization across repeating elements could be a mechanism to extract general principles about related experiences
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