Study of the cavitating instability on a grooved Venturi profile

Cavitation is a limiting phenomenon in many domains of fluid mechanics. Instabilities of a partial cavity developed on an hydrofoil, a converging-diverging step or in an inter-blade channel in turbomachinery, have already been investigated and described in many previous works. The aim of this study is to evaluate a passive control method of the sheet cavity. According to operating conditions, cavitation can be described by two different regimes: an unstable regime with a cloud cavitation shedding and a stable regime with only a pulsating sheet cavity. Avoiding cloud cavitation can limit structure damages since a pulsating sheet cavity is less agressive. The surface condition of a converging-diverging step, like a Venturi-type obstacle, is here studied as a solution for a passive control of the cavitation. This study discusses the effect of an organized roughness, in the shape of longitudinal grooves, on the developed sheet cavity. Analyzes conducted with Laser Doppler Velocimetry, visualisations and pressure measurements show that the grooves geometry, and especially the groove depth, acts on the sheet cavity dynamics. Results show that modifying the surface condition, by varying the grooves geometry, can reduce cavity sheet length and even suppress the cloud cavitation shedding.Comment: Submitted to Journal of Fluids Engineerin

Development of a microelectronic module Final report

Feasibility of operating gallium arsenide devices in high temperature microelectronic circuit

Bayesian Classification Using Probabilistic Graphical Models

Bayesian Classifiers are used to classify unseen observations to one of the probable class category (also called class labels). Classification applications have one or more features and one or more class variables. Naïve Bayes Classifier is one of the simplest classifier used in practice. Though Naïve Bayes Classifier performs well in practice (in terms of its prediction accuracy), it assumes strong independence among features given class variable. Naïve Bayes assumption may reduce prediction accuracy when two or more features are dependent given class variable. In order to improve prediction accuracy, we can relax Naïve Bayes assumption and allow dependencies among features given class variable. Capturing feature dependencies more likely improves prediction accuracy for classification applications in which two (or more) features have some correlation given class variable. The purpose of this project is to exploit these feature dependencies to improve prediction by discovering them from input data. Probabilistic Graphical Model concepts are used to learn Bayesian Classifiers effectively and efficiently

Intestinal fungi contribute to development of alcoholic liver disease

This study was supported in part by NIH grants R01 AA020703, U01 AA021856 and by Award Number I01BX002213 from the Biomedical Laboratory Research & Development Service of the VA Office of Research and Development (to B.S.). K.H. was supported by a DFG (Deutsche Forschungsgemeinschaft) fellowship (HO/ 5690/1-1). S.B. was supported by a grant from the Swiss National Science Foundation (P2SKP3_158649). G.G. received funding from the Yale Liver Center NIH P30 DK34989 and R.B. from NIAAA grant U01 AA021908. A.K. received support from NIH grants RC2 AA019405, R01 AA020216 and R01 AA023417. G.D.B. is supported by funds from the Wellcome Trust. We acknowledge the Human Tissue and Cell Research (HTCR) Foundation for making human tissue available for research and Hepacult GmbH (Munich, Germany) for providing primary human hepatocytes for in vitro analyses. We thank Dr. Chien-Yu Lin Department of Medicine, Fu-Jen Catholic University, Taiwan for statistical analysis.Peer reviewedPublisher PD

Understanding the Role of Eed Deletion in Medulloblastoma

Medulloblastoma, the most common malignant pediatric brain cancer, is uniquely sensitive to DNA damage-inducing therapies, with conventional treatment resulting in an 80% 5-year survival rate. Researching the apoptotic pathways that make treatment effective in some tumors and how those pathways contribute to resistance in others may identify therapies that reduce the need for toxic radiation and chemotherapy. In cerebellar development, physiologic Sonic Hedgehog (SHH) signaling drives proliferation of cerebellar granule neuron progenitors (CGNPs). Similarly, pathologic SHH hyperactivation drives proliferation in SHH-subgroup medulloblastoma, which makes up 30% of medulloblastoma cases. SHH signaling upregulates target genes in part by preventing H3K27 trimethylation marks via the JMJD3/KDM6B demethylase complex. In differentiated cerebellar neurons, where SHH signaling is low, the polycomb repressive complex 2 (PRC2) silences SHH target genes by trimethylating H3K27 residues in regulatory regions. Our data show that blocking the PRC2 through genetic deletion has varying effects in different contexts. When the PRC2-component Eed is deleted in SHH-subtype medulloblastomas that form in mice engineered for SHH hyperactivation, the tumors show initially slower growth compared to tumors in Eed-intact controls; however, the mice have significantly poorer survival. Therefore, this study aims to understand the mechanisms of initially reduced tumor growth and ultimately more rapid tumor progression. Our recent single cell gene expression analysis showed that Eed deletion in CGNPs induced genes involved in muscle cell differentiation, including myogenin and troponin. We will characterize Eed-deleted medulloblastoma using fluorescence-activated cell sorting (FACS) as well as immunohistochemistry (IHC). The first aim of this study is to elucidate how cell cycle dynamics are altered in Eed-deleted medulloblastomas. The second aim of the study tests whether Eed deletion alters the levels of cell cycle markers, cell death, and aberrant expression of muscular proteins in SHH-driven medulloblastoma. Our cell cycle studies show that Eed deletion slows tumor growth in early development, but the tumor later develops EED independence, resulting in more rapid progression and decreased survival. Additionally, our data show that Eed deletion alters the expression of proteins related to proliferation, differentiation, apoptosis, and muscle development.Bachelor of Scienc

Study of passive control study of the cavitation instability on a venturi profile

This paper presents experimental and numerical results concerning the operation of a configuration that includes an axial pump and a bundle of tubes that mimics the cool source of a heat exchanger. The pump used in the tests has a low solidity and two blades designed in forced vortex, the tip clearance is approximately 3.87% of tip radius. The experimental measures of the characteristic curves and of the wall static pressure fluctuations signals upstream and downstream the pump and the exchanger were compared to the numerical results. The numerical simulations were carried out by using a Fluent code, with URANS (Unsteady Reynolds Averaged Navier-Stokes) approach and k-w SST turbulence model

Mutagenesis of Acinetobacter Baumannii A118

Acinetobacter baumannii is a gram negative, nosocomial pathogen, which has ability to gain resistance against antibiotics. According to CDC antibiotic resistance threats report, 2013, approximately 500 deaths happen annually in the United States of America (U.S.A) (26). The A. baumannii A118 strain was found to be susceptible to several known antibiotics and naturally competent, which was helpful for the genetic study of the A118 strain. In this research, the entA gene was selected to be replaced with the kanamycin resistant gene (KanR) to get the A118 mutant. The entA gene encodes the enzyme that catalyzes the production of the 2,3-dihydroxybenzoic acid (DHBA), which participates in the biosynthesis of the acinetobactin siderophore. To achieve the mutation, homologous recombination mechanism was followed. The KanR gene, attached with the flanking regions homologous to the entA gene flanking regions was ligated into pCVD442 vector, giving pMDMT1 recombinant plasmid. A. baumannii A118 cells were transformed with the pMDMT1 recombinant plasmid and the transformants were analyzed to check the mutation. There were no conclusive results for the mutation, but successful recombinant plasmid pMDMT1 was achieved.978035516426

Study of passive control study of the cavitation instability on a venturi profile

This paper presents experimental and numerical results concerning the operation of a configuration that includes an axial pump and a bundle of tubes that mimics the cool source of a heat exchanger. The pump used in the tests has a low solidity and two blades designed in forced vortex, the tip clearance is approximately 3.87% of tip radius. The experimental measures of the characteristic curves and of the wall static pressure fluctuations signals upstream and downstream the pump and the exchanger were compared to the numerical results. The numerical simulations were carried out by using a Fluent code, with URANS (Unsteady Reynolds Averaged Navier-Stokes) approach and k-w SST turbulence model

Ammonia-induced brain edema requires macrophage and T cell expression of Toll-like receptor 9

BACKGROUND &amp; AIM: Ammonia is central in the pathogenesis of brain edema in acute liver failure (ALF) with infection and systemic inflammation expediting development of intracranial hypertension (ICH). Patients with acetaminophen-induced ALF have increased neutrophil TLR9 expression which can be induced by ammonia. We determined whether ammonia-induced brain edema and immune dysfunction are mediated by TLR9 and if this could be prevented in a TLR9-deficient mouse model.METHODS: Ammonium acetate (NH4-Ac; 4mmol/kg) was injected intraperitoneally in wild type (WT), Tlr9-/- and Lysm-Cre Tlr9fl/fl mice (TLR9 absent in neutrophils and macrophages including Kupffer cells) and compared to controls. Six hours after NH4-Ac injection, intracellular cytokine production was determined in splenic macrophages, CD4+ and CD8+ T cells. Brain water (BW) and total plasma DNA (tDNA) were also measured. The impact of the TLR9 antagonist ODN2088 (50μg/mouse) was evaluated.RESULTS: Following NH4-Ac injection, BW, macrophage and T cell cytokine production increased (p&lt;0.0001) in WT but not Tlr9-/- mice (p&lt;0.001). ODN2088 inhibited macrophage and T cell cytokine production (p&lt;0.05) and prevented an increase in BW (p&lt;0.0001). Following NH4-Ac injection, macrophage cytokine production and BW were ameliorated in Lysm-Cre Tlr9fl/fl mice compared to WT mice (p&lt;0.05) but there was no difference compared to Tlr9-/- mice. Following NH4-Ac injection, plasma tDNA levels increased in WT and Tlr9-/- mice (p&lt;0.05) suggesting that TLR9 may be activated by DNA released from ammonia-stimulated cells.CONCLUSION: Ammonia-induced brain edema requires macrophage and T cell expression of TLR9. Amelioration of brain edema and lymphocyte cytokine production by ODN2088 supports exploration of TLR9 antagonism in early ALF to prevent progression to ICH.</p