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  • 1
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    Genetic analysis of digestive physiology using fluorescent phospholipid reporters (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-05-19
    Description: Zebrafish are a valuable model for mammalian lipid metabolism; larvae process lipids similarly through the intestine and hepatobiliary system and respond to drugs that block cholesterol synthesis in humans. After ingestion of fluorescently quenched phospholipids, endogenous lipase activity and rapid transport of cleavage products results in intense gall bladder fluorescence. Genetic screening identifies zebrafish mutants, such as fat free, that show normal digestive organ morphology but severely reduced phospholipid and cholesterol processing. Thus, fluorescent lipids provide a sensitive readout of lipid metabolism and are a powerful tool for identifying genes that mediate vertebrate digestive physiology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Farber, S A -- Pack, M -- Ho, S Y -- Johnson, I D -- Wagner, D S -- Dosch, R -- Mullins, M C -- Hendrickson, H S -- Hendrickson, E K -- Halpern, M E -- DK 54942/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 2001 May 18;292(5520):1385-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21210, USA. sfarber@lac.jci.tju.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11359013" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anticholesteremic Agents/pharmacology ; Atorvastatin Calcium ; Bile Acids and Salts/pharmacology ; Boron Compounds/metabolism ; Cholesterol/metabolism ; Digestive System/drug effects/*metabolism/pathology ; *Digestive System Physiological Phenomena/drug effects ; Fluorescent Dyes/*metabolism ; Gallbladder/drug effects/metabolism ; Heptanoic Acids/pharmacology ; Larva/drug effects/metabolism ; Lipase/metabolism ; Mice ; Microscopy, Fluorescence ; Microscopy, Video ; Mutation/genetics ; Phospholipids/*metabolism ; Pyrroles/pharmacology ; Signal Transduction/drug effects ; Zebrafish/embryology/genetics/*metabolism/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Lethargus is a Caenorhabditis elegans sleep-like state (2008)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2008-01-11
    Description: There are fundamental similarities between sleep in mammals and quiescence in the arthropod Drosophila melanogaster, suggesting that sleep-like states are evolutionarily ancient. The nematode Caenorhabditis elegans also has a quiescent behavioural state during a period called lethargus, which occurs before each of the four moults. Like sleep, lethargus maintains a constant temporal relationship with the expression of the C. elegans Period homologue LIN-42 (ref. 5). Here we show that quiescence associated with lethargus has the additional sleep-like properties of reversibility, reduced responsiveness and homeostasis. We identify the cGMP-dependent protein kinase (PKG) gene egl-4 as a regulator of sleep-like behaviour, and show that egl-4 functions in sensory neurons to promote the C. elegans sleep-like state. Conserved effects on sleep-like behaviour of homologous genes in C. elegans and Drosophila suggest a common genetic regulation of sleep-like states in arthropods and nematodes. Our results indicate that C. elegans is a suitable model system for the study of sleep regulation. The association of this C. elegans sleep-like state with developmental changes that occur with larval moults suggests that sleep may have evolved to allow for developmental changes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Raizen, David M -- Zimmerman, John E -- Maycock, Matthew H -- Ta, Uyen D -- You, Young-jai -- Sundaram, Meera V -- Pack, Allan I -- England -- Nature. 2008 Jan 31;451(7178):569-72. doi: 10.1038/nature06535. Epub 2008 Jan 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Sleep and Respiratory Neurobiology, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania 19104, USA. raizen@mail.med.upenn.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18185515" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arousal/genetics/physiology ; Biological Evolution ; Caenorhabditis elegans/enzymology/genetics/*physiology ; Caenorhabditis elegans Proteins/genetics/metabolism ; Conserved Sequence/genetics ; Cyclic GMP-Dependent Protein Kinases/genetics/metabolism ; Drosophila melanogaster/genetics/physiology ; Homeostasis/physiology ; Larva/physiology ; Lethargy ; Molting/physiology ; Sleep/genetics/*physiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Differential lysosomal proteolysis in antigen-presenting cells determines antigen fate (2005)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2005-03-12
    Description: Antigen-presenting cells (APCs) internalize antigens and present antigen-derived peptides to T cells. Although APCs have been thought to exhibit a well-developed capacity for lysosomal proteolysis, here we found that they can exhibit two distinct strategies upon antigen encounter. Whereas macrophages contained high levels of lysosomal proteases and rapidly degraded internalized proteins, dendritic cells (DCs) and B lymphocytes were protease-poor, resulting in a limited capacity for lysosomal degradation. Consistent with these findings, DCs in vivo degraded internalized antigens slowly and thus retained antigen in lymphoid organs for extended periods. Limited lysosomal proteolysis also favored antigen presentation. These results help explain why DCs are able to efficiently accumulate, process, and disseminate antigens and microbes systemically for purposes of tolerance and immunity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Delamarre, Lelia -- Pack, Margit -- Chang, Henry -- Mellman, Ira -- Trombetta, E Sergio -- R37-AI34098/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2005 Mar 11;307(5715):1630-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology and Department of Immunobiology, Ludwig Institute for Cancer Research, Yale University School of Medicine, 333 Cedar Street, Post Office Box 208002, New Haven, CT 06520-8002, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15761154" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antigen Presentation ; Antigen-Presenting Cells/*enzymology/*immunology/metabolism ; Antigens/*metabolism ; B-Lymphocytes/enzymology/immunology/metabolism ; Cells, Cultured ; Dendritic Cells/*enzymology/immunology/metabolism ; Endocytosis ; Green Fluorescent Proteins/immunology/metabolism ; Histocompatibility Antigens Class II/immunology ; Horseradish Peroxidase/immunology/metabolism ; Lymphoid Tissue/cytology/enzymology/immunology ; Lysosome-Associated Membrane Glycoproteins ; Lysosomes/*enzymology/ultrastructure ; Macrophages/enzymology/immunology/metabolism ; Membrane Glycoproteins/metabolism ; Mice ; Mice, Inbred C3H ; Peptide Hydrolases/*metabolism ; Ribonuclease, Pancreatic/immunology/metabolism ; Ribonucleases/immunology/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Overview of Active Flow Control at NASA Langley Research Center (1998)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The paper summarizes Active Flow Control projects currently underway at the NASA Langley Research Center. Technology development is being pursued within a multidisciplinary, cooperative approach, involving the classical disciplines of fluid mechanics, structural mechanics, material science, acoustics, and stability and control theory. Complementing the companion papers in this session, the present paper will focus on projects that have the goal of extending the state-of-the-art in the measurement, prediction, and control of unsteady, nonlinear aerodynamics. Toward this goal, innovative actuators, micro and macro sensors, and control strategies are considered for high payoff flow control applications. The target payoffs are outlined within each section below. Validation of the approaches range from bench-top experiments to wind-tunnel experiments to flight tests. Obtaining correlations for future actuator and sensor designs are implicit in the discussion. The products of the demonstration projects and design tool development from the fundamental NASA R&D level technology will then be transferred to the Applied Research components within NASA, DOD, and US Industry. Keywords: active flow control, separation control, MEMS, review
    Keywords: Fluid Mechanics and Thermodynamics
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  • 5
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    Multiple Mode Actuation of a Turbulent Jet (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is pi +/- pi/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2001-0735 , Aerospace Sciences; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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  • 6
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    Multiple Mode Actuation of a Turbulent Jet (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is pi +/- pi/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2001-0735 , Aerospace Sciences; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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  • 7
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    Sweeping Jet Optimization Studies (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Progress on experimental efforts to optimize sweeping jet actuators for active flow control (AFC) applications with large adverse pressure gradients is reported. Three sweeping jet actuator configurations, with the same orifice size but dierent internal geometries, were installed on the flap shoulder of an unswept, NACA 0015 semi-span wing to investigate how the output produced by a sweeping jet interacts with the separated flow and the mechanisms by which the flow separation is controlled. For this experiment, the flow separation was generated by deflecting the wing's 30% chord trailing edge flap to produce an adverse pressure gradient. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the three actuator configurations. The actuator with the largest jet deflection angle, at the pressure ratios investigated, was the most efficient at controlling flow separation on the flap of the model. Oil flow visualization studies revealed that the flow field controlled by the sweeping jets was more three-dimensional than expected. The results presented also show that the actuator spacing was appropriate for the pressure ratios examined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-22842 , 2016 AIAA Aviation Technology, Integration, and Operations Conference; Jun 13, 2016 - Jun 17, 2016; Washington, DC; United States
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  • 8
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    Active Flow Control Using Sweeping Jet Actuators on a Semi-Span Wing Model (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Wind tunnel experiments were performed using active flow control on an unswept semispan wing model with a 30% chord trailing edge flap to aid in the selection of actuators for a planned high Reynolds number experiment. Two sweeping jet actuator sizes were investigated to determine the influence of actuator size on the active flow control system efficiency. Sweeping jet actuators with orifice sizes of 1 mm x 2 mm and 2 mm x 4 mm were selected because of the differences in actuator jet sweep angle. The parameters that were varied include actuator momentum, freestream velocity, and trailing edge flap deflection angle. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the two actuators. In addition to the wind tunnel experiments, benchtop studies of the actuators were performed to characterize the jets produced by each actuator. Benchtop investigations of the smaller actuator reveal that the jet exiting the actuator has a reduced sweep angle compared to published data for larger versions of this type of actuator. The larger actuator produces an oscillating jet that attaches to the external diuser walls at low supply pressures and produces the expected sweep angles. The AFC results using the smaller actuators show that while the actuators can control flow separation, the selected spacing of 3.3 cm may be too large due to the reduced sweep angle. In comparison, the spacing for the larger actuators, 6.6 cm, appears to be optimal for the Mach numbers investigated. Particle Image Velocimetry results are presented and show how the wall jets produced by the actuators cause the flow to attach to the flap surface.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-21616 , AIAA SciTech Conference; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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