Forced internal convection mist cooling heat transfer

Issued as final reportThis report describes work completed and results achieved on the” Forced Internal Convection Mist Cooling Heat Transfer” project from its inception on November 4, 2002 through its conclusion on August 31, 2013. This work involved close collaboration between the Georgia Institute of Technology (GT), the Schoonover Consulting Group (SCG), and the Naval Research Laboratory (NRL). The primary goal of the project was to design, develop, and test a system to adequately cool the Hibachi foils in the Electra KrF laser at the Naval Research Laboratory in Washington, DC. Though it took several iterations, we did successfully devise a system which met the goal of keeping the foils cool with minimal disruption to the focal profile or efficiency of the laser. By withdrawing a relatively small amount of KrF gas from the laser and redirecting it towards the Hibachi foils in the form of hundreds of tiny high velocity near-wall jets the foils showed a dramatic decrease in temperature. Focal profile measurements of the laser beam were far better than that achieved by any other cooling system. It is unfortunate that Congressional funding cuts scuttled the Electra program before we were able to complete full-scale, long-term testing with gas recirculation.Schoonover Consulting Grou

The Effect of Water Depth on Energy Expenditure and Perception of Effort in Female Subjects While Walking

The purpose of this study was to compare energy expenditure (EE), heart rate, and perceived effort during walking in water at several depths versus land in female participants. Eighteen females walked on three separate days on a land treadmill (Land) and in a water treadmill (ATM) at 30° C at 6 speeds. Water depth was at the xiphoid (xip), 10 cm below (-10 cm), and 10 cm above xip (+10 cm). Heart rate (HR), oxygen consumption (VO2) and carbon dioxide production (VCO2) were recorded. RPE overall (RPE-O) and RPE legs (RPE-L) were solicited following each bout. Regardless of walking speed, EE and HR were influenced by water depth, with -10 cm significantly greater than xip, +10 cm and Land, and xip significantly greater than +10 cm and Land (all p \u3c 0.001). Land EE and HR were similar to +10 cm. RPE-O was significantly higher for -10 cm vs. xip, +10 cm, and Land, while xip was greater than Land. RPE-L was greater for -10 cm vs. xip, +10 cm and Land, while xip was greater than +10 cm & Land. Our results showed that small changes in water depth influences exercise EE, HR and RPE. These differences are attributed to a changing relationship between drag resistances and buoyancy in water

A trajectory-based sampling strategy for sequentially refined metamodel management of metamodel-based dynamic optimization in mechatronics

Dynamic optimization problems based on computationally expensive models that embody the dynamics of a mechatronic system can result in prohibitively long optimization runs. When facing optimization problems with static models, reduction in the computational time and thus attaining convergence can be established by means of a metamodel placed within a metamodel management scheme. This paper proposes a metamodel management scheme with a dedicated sampling strategy when using computationally demanding dynamic models in a dynamic optimization problem context. The dedicated sampling strategy enables to attain dynamically feasible solutions where the metamodel is locally refined during the optimization process upon satisfying a feasibility-based stopping condition. The samples are distributed along the iterate trajectories of the sequential direct dynamic optimization procedure. Algorithmic implementation of the trajectory-based metamodel management is detailed and applied on two case studies involving dynamic optimization problems. These numerical experiments illustrate the benefits of the presented scheme and its sampling strategy on the convergence properties. It is shown that the acceleration of the solution time of the dynamic optimization problem can be achieved when evaluating the metamodel that is lower than 90% compared to the computationally expensive model

Bipolar spintronics: From spin injection to spin-controlled logic

An impressive success of spintronic applications has been typically realized in metal-based structures which utilize magnetoresistive effects for substantial improvements in the performance of computer hard drives and magnetic random access memories. Correspondingly, the theoretical understanding of spin-polarized transport is usually limited to a metallic regime in a linear response, which, while providing a good description for data storage and magnetic memory devices, is not sufficient for signal processing and digital logic. In contrast, much less is known about possible applications of semiconductor-based spintronics and spin-polarized transport in related structures which could utilize strong intrinsic nonlinearities in current-voltage characteristics to implement spin-based logic. Here we discuss the challenges for realizing a particular class of structures in semiconductor spintronics: our proposal for bipolar spintronic devices in which carriers of both polarities (electrons and holes) contribute to spin-charge coupling. We formulate the theoretical framework for bipolar spin-polarized transport, and describe several novel effects in two- and three-terminal structures which arise from the interplay between nonequilibrium spin and equilibrium magnetization.Comment: 16 pages, 7 figure

Whole Transcriptome Sequencing Reveals Gene Expression and Splicing Differences in Brain Regions Affected by Alzheimer's Disease

Recent studies strongly indicate that aberrations in the control of gene expression might contribute to the initiation and progression of Alzheimer's disease (AD). In particular, alternative splicing has been suggested to play a role in spontaneous cases of AD. Previous transcriptome profiling of AD models and patient samples using microarrays delivered conflicting results. This study provides, for the first time, transcriptomic analysis for distinct regions of the AD brain using RNA-Seq next-generation sequencing technology. Illumina RNA-Seq analysis was used to survey transcriptome profiles from total brain, frontal and temporal lobe of healthy and AD post-mortem tissue. We quantified gene expression levels, splicing isoforms and alternative transcript start sites. Gene Ontology term enrichment analysis revealed an overrepresentation of genes associated with a neuron's cytological structure and synapse function in AD brain samples. Analysis of the temporal lobe with the Cufflinks tool revealed that transcriptional isoforms of the apolipoprotein E gene, APOE-001, -002 and -005, are under the control of different promoters in normal and AD brain tissue. We also observed differing expression levels of APOE-001 and -002 splice variants in the AD temporal lobe. Our results indicate that alternative splicing and promoter usage of the APOE gene in AD brain tissue might reflect the progression of neurodegeneration

Central Exercise Action Increases the AMPK and mTOR Response to Leptin

AMP-activated protein kinase (AMPK) and mammalian Target of Rapamycin (mTOR) are key regulators of cellular energy balance and of the effects of leptin on food intake. Acute exercise is associated with increased sensitivity to the effects of leptin on food intake in an IL-6-dependent manner. To determine whether exercise ameliorates the AMPK and mTOR response to leptin in the hypothalamus in an IL-6-dependent manner, rats performed two 3-h exercise bouts, separated by one 45-min rest period. Intracerebroventricular IL-6 infusion reduced food intake and pretreatment with AMPK activators and mTOR inhibitor prevented IL-6-induced anorexia. Activators of AMPK and fasting increased food intake in control rats to a greater extent than that observed in exercised ones, whereas inhibitor of AMPK had the opposite effect. Furthermore, the reduction of AMPK and ACC phosphorylation and increase in phosphorylation of proteins involved in mTOR signal transduction, observed in the hypothalamus after leptin infusion, were more pronounced in both lean and diet-induced obesity rats after acute exercise. Treatment with leptin reduced food intake in exercised rats that were pretreated with vehicle, although no increase in responsiveness to leptin-induced anorexia after pretreatment with anti-IL6 antibody, AICAR or Rapamycin was detected. Thus, the effects of leptin on the AMPK/mTOR pathway, potentiated by acute exercise, may contribute to appetite suppressive actions in the hypothalamus

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder