344 research outputs found

    Canonical description of incompressible fluid -- Dirac brackets approach

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    We present a novel canonical description of the incompressible fluid dynamics. This description uses the dynamical constraints, in our case reflecting "incompressibility" assumption, and leads to replacement of usual hydrodynamical Poisson brackets for density and velocity fields with Dirac brackets. The resulting equations are then known nonlinear, and non-local in space, equations for incompressible fluid velocity.Comment: 7 pages, late

    Antifungal activity of Myrtus communis and Zygophyllum album extracts against human pathogenic fungi

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    Fungal infections have been increasing in recent years due to a growing number of high-risk patients, particularly immunocompromised hosts. Currently, medicinal plants are known for their properties due to their essential oils and phenolic compounds. They have been empirically used as antimicrobial agents. So the composition of the phenolic extracts and essential oils of Myrtus communis and Zygophyllum album and their antifungal activity on Candida albicans, Aspergillus fumigatus fungal strains were studied. In this fact, essential oils from the aerial parts of the plant were obtained by hydrodistillation and analyzed by GC and GC-MS, for the phenolic extracts, several extraction methods with a preliminary phytochemical study were applied. The oils showed high contents of α-pinene and cineol for M. communis and verbenone and caryophyllene for the Z. album. The MIC and minimal lethal concentration were used to evaluate the antifungal activity against Candida and Aspergillus strains. Results showed that M. communis and Z. album essential oil and phenolic extracts exhibited a significant activity against clinically relevant fungi, a significant antifungal activity of the two extracts studied (MCA and ZAM) was observed on C. albicans of these, two extracts, MCA was found to be most active with an MFC value of 25 mg/ml versus 100 mg/ml for ZAM. Nevertheless, the essential oils exhibited stronger antifungal activity than the phenolic extracts. The present study indicates that the two medicinal plants have considerable antifungal activity, deserving further investigation for clinical applications. DOI: http://dx.doi.org/10.5281/zenodo.375120

    A novel AhR ligand, 2AI, protects the retina from environmental stress.

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    Various retinal degenerative diseases including dry and neovascular age-related macular degeneration (AMD), retinitis pigmentosa, and diabetic retinopathy are associated with the degeneration of the retinal pigmented epithelial (RPE) layer of the retina. This consequently results in the death of rod and cone photoreceptors that they support, structurally and functionally leading to legal or complete blindness. Therefore, developing therapeutic strategies to preserve cellular homeostasis in the RPE would be a favorable asset in the clinic. The aryl hydrocarbon receptor (AhR) is a conserved, environmental ligand-dependent, per ARNT-sim (PAS) domain containing bHLH transcription factor that mediates adaptive response to stress via its downstream transcriptional targets. Using in silico, in vitro and in vivo assays, we identified 2,2'-aminophenyl indole (2AI) as a potent synthetic ligand of AhR that protects RPE cells in vitro from lipid peroxidation cytotoxicity mediated by 4-hydroxynonenal (4HNE) as well as the retina in vivo from light-damage. Additionally, metabolic characterization of this molecule by LC-MS suggests that 2AI alters the lipid metabolism of RPE cells, enhancing the intracellular levels of palmitoleic acid. Finally, we show that, as a downstream effector of 2AI-mediated AhR activation, palmitoleic acid protects RPE cells from 4HNE-mediated stress, and light mediated retinal degeneration in mice

    Frequency dispersion reduction and bond conversion on n-type GaAs by in situ surface oxide removal and passivation

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    The method of surface preparation on n-type GaAs, even with the presence of an amorphous-Si interfacial passivation layer, is shown to be a critical step in the removal of accumulation capacitance frequency dispersion. In situ deposition and analysis techniques were used to study different surface preparations, including NH4OH, Si-flux, and atomic hydrogen exposures, as well as Si passivation depositions prior to in situ atomic layer deposition of Al2O3. As–O bonding was removed and a bond conversion process with Si deposition is observed. The accumulation capacitance frequency dispersion was removed only when a Si interlayer and a specific surface clean were combined

    GaAs interfacial self-cleaning by atomic layer deposition

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    The reduction and removal of surface oxides from GaAs substrates by atomic layer deposition (ALD) of Al2O3 and HfO2 are studied using in situ monochromatic x-ray photoelectron spectroscopy. Using the combination of in situ deposition and analysis techniques, the interfacial "self-cleaning" is shown to be oxidation state dependent as well as metal organic precursor dependent. Thermodynamics, charge balance, and oxygen coordination drive the removal of certain species of surface oxides while allowing others to remain. These factors suggest proper selection of surface treatments and ALD precursors can result in selective interfacial bonding arrangements

    Chemical composition and anti-arthritic activity of Anacyclus valentinus extract on adjuvant-induced arthritis in rats

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    Anacyclus valentinus L. is a common annual plant in Algeria, known for her various therapeutic effects. In addition, the plant is used as a food condiment. We reported our investigations on the chemical compositions and the antiarthritic activity of methanolic extract of A. valentinus (MEAV). The polyphenol extraction by maceration with methanol (80%) gave yields of 17.82%. The identification by LC-MS and colorimetric assays revealed the wealth of methanolic extracts on phenolic compounds including flavonoids (52.15 mg Equ/g) and lactones. Acute oral toxicity of extract was performed in line with OECD guidelines and the lethal dose 50 was assessed greater than 2500 mg/Kg. Regarding the anti-arthritic power, rheumatoid arthritis was induced by Freund\u27s adjuvant in rats. The methanolic extract of A. valentinus presented a largest effect with weight gain, an arthritic score, thymus indices; spleen and serum parameters close to those of the control. The extract also inhibited edema and restored cartilage structure

    Galactomannan Does Not Precede Major Signs on a Pulmonary Computerized Tomographic Scan Suggestive of Invasive Aspergillosis in Patients with Hematological Malignancies

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    Background. Detection of serum galactomannan (GM) antigen and presence of the halo sign on a pulmonary computerized tomographic (CT) scan have a high specificity but a low sensitivity to diagnose invasive aspergillosis (IA) in patients at risk for this disease. To our knowledge, the relationship between the time at which pulmonary infiltrates are detected by CT and the time at which GM antigens are detected by enzyme immunoassay (EIA) has not been studied. Methods. In a prospective study, tests for detection of GM were performed twice weekly for patients with hematological malignancies who had undergone hematopoetic stem cell transplantation (HSCT) or had received induction and/or consolidation chemotherapy. A pulmonary CT scan was performed once weekly. Infiltrates were defined as either major or minor signs. IA was classified as proven, probable, or possible, in accordance with the definition stated by the European Organization for Research and Treatment of Cancer-Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group. Results. We analyzed 161 episodes of infection in 107 patients (65 allogeneic HSCT recipients, 30 autologous HSCT recipients, and 66 induction and/or consolidation chemotherapy recipients). A total of 109 episodes with no IA, 32 episodes with possible IA, and 20 episodes with probable or proven IA were identified. Minor pulmonary signs were detected by CT in 70 episodes (43%), and major pulmonary signs were detected by CT in 11 episodes (7%). Univariate and multivariate analyses revealed no significant association between detection of GM by EIA and detection of abnormal pulmonary signs by CT. A significant association was found between GM levels and receipt of piperacillin-tazobactam. GM test results were not positive before major signs were seen on CT images. Only 7 (10%) of 70 patients with minor pulmonary signs had positive GM test results before detection of the greatest pathologic change by CT. Conclusions. We show that detection of GM by EIA does not precede detection of major lesions by pulmonary CT. In the clinical setting, the decision to administer mold-active treatment should based on detection of new pulmonary infiltrates on CT performed early during infection, rather than on results of EIA for detection of G

    Hydrodynamics of topological defects in nematic liquid crystals

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    We show that back-flow, the coupling between the order parameter and the velocity fields, has a significant effect on the motion of defects in nematic liquid crystals. In particular the defect speed can depend strongly on the topological strength in two dimensions and on the sense of rotation of the director about the core in three dimensions.Comment: 4 pages including two figure

    Inaccurate forecasting of a randomized controlled trial

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    Published online: 22 November 2023We report the results of a forecasting experiment about a randomized controlled trial that was conducted in the field. The experiment asks Ph.D. students, faculty, and policy practitioners to forecast (1) compliance rates for the RCT and (2) treatment effects of the intervention. The forecasting experiment randomizes the order of questions about compliance and treatment effects and the provision of information that a pilot experiment had been conducted which produced null results. Forecasters were excessively optimistic about treatment effects and unresponsive to item order as well as to information about a pilot. Those who declare themselves expert in the area relevant to the intervention are particularly resistant to new information that the treatment is ineffective. We interpret our results as suggesting that we should exercise caution when undertaking expert forecasting, since experts may have unrealistic expectations and may be inflexible in altering these even when provided new information
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