Numerical solutions of the inertial modes of the earth's fluid core : from the outstanding problem of the incompressible fluid shell to more realistic up to date core models

In this work we study the inertial modes of a rotating spheroidal fluid shell proportional to the Earth's fluid core. We start with the long standing problem of the modes of an incompressible and inviscid spherical fluid shell. Traditionally, a second order equation describing the pressure field of the flow, subject to the impermeability boundary condition, is solved for the eigenfrequencies and eigenfunctions of the flow. These equations are scalar hyperbolic boundary value second-order Partial Differential Equations (PDEs) which are ill-posed problems in the sense that the existence of the analytical solutions depends on the geometry of the container. The problem admits analytical solutions in a sphere but not in a spherical shell. We use the Galekin method to solve the momentum and the continuity equation together and compute the frequencies, pressure and displacement eigenfunctions for some of the low order, wavenumbers $m=0$ and $m=1$, inertial modes of this model. To show that our approach is correct we compute the inertial modes of a homogeneous, incompressible and inviscid fluid sphere for which analytical solutions for the inertial modes exist. We also compute the inertial modes of a more realistic uniformly rotating, compressible, self gravitation and inviscid fluid core model. Finally, we extend the governing equations to include first order terms in the ellipticity. In order to minimize effects of the derivatives of the material properties which are poorly determined in the existing Earth models, a Clairaut coordinate system is used to map the elliptical equipotential surfaces into the spherical ones. Also, the divergence theorem is used to implement the boundary equations.Natural Sciences and Engineering Research Council (NSERC) of Canada , School of Graduate Studies (SGS

Optimization of cloud point extraction procedure with response surface methodology for quantification of iron by means of flame atomic absorption spectrometry

A simple micelle-mediated phase separation method has been developed for the pre-concentration of trace levels of iron as a prior step to determination by flame atomic absorption spectrometry (FAAS). The method is based on the cloud point extraction (CPE) of iron using non-ionic surfactant polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5) without adding any chelating agent. Several variables affecting the extraction efficiency were studied and optimized utilizing central composite design (CCD) and three levels full factorial design. Under the optimum conditions, the limit of detection (LOD), limit of quantification (LOQ) and pre-concentration factor were 1.5 μg L-1, 5.0 μg L-1 and 100, respectively. The relative standard deviation (RSD) for six replicate determinations at 50 μg L−1 Fe(III) level was 1.97%. The calibration graph was linear in the rage of 5-100 μg L-1, with a correlation coefficient of 0.9921. The developed method was validated by the analysis of two certified reference materials and applied successfully to the determination of trace amounts of Fe(III) in water and rice samples

Evaluating the Impact of Flaky Simulators on Testing Autonomous Driving Systems

Simulators are widely used to test Autonomous Driving Systems (ADS), but their potential flakiness can lead to inconsistent test results. We investigate test flakiness in simulation-based testing of ADS by addressing two key questions: (1) How do flaky ADS simulations impact automated testing that relies on randomized algorithms? and (2) Can machine learning (ML) effectively identify flaky ADS tests while decreasing the required number of test reruns? Our empirical results, obtained from two widely-used open-source ADS simulators and five diverse ADS test setups, show that test flakiness in ADS is a common occurrence and can significantly impact the test results obtained by randomized algorithms. Further, our ML classifiers effectively identify flaky ADS tests using only a single test run, achieving F1-scores of $85$%, $82$% and $96$% for three different ADS test setups. Our classifiers significantly outperform our non-ML baseline, which requires executing tests at least twice, by $31$%, $21$%, and $13$% in F1-score performance, respectively. We conclude with a discussion on the scope, implications and limitations of our study. We provide our complete replication package in a Github repository.Comment: Accepted for publication by Empirical Software Engineering Journal (EMSE) (in November 2023

Fabrication, characterization, and magnetic properties of copper ferrite nanoparticles prepared by a simple, thermal-treatment method

Tetragonal copper ferrite nanoparticles were fabricated by a thermal-treatment method by using a solution that contained poly(vinyl alcohol) (PVA) as a capping agent and Cu and Fe nitrates as alternative sources of metal. Heat treatment was conducted at temperatures between 673 and 823 K, and final products had different crystallite sizes ranging from 11 to 42 nm. The influence of calcination temperature on the degree of crystallinity, morphology, microstructure, and phase composition was investigated by different characterization techniques, i.e., X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscope (FESEM), and Fourier transform infrared (FT-IR) spectroscopy, respectively. The compositions of the samples were determined by energy dispersion X-ray analysis (EDXA), which revealed the presence of Cu, Fe, and O in the samples. The formed nanoparticles exhibited ferromagnetic behavior with unpaired electrons spins, which was confirmed by using a vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy

Synthesis and characterization of zinc ferrite nanoparticles by a thermal treatment method

Crystalline zinc ferrite (ZnFe2O4) was prepared by the thermal treatment method, followed by calcination at various temperatures from 723 to 873 K. Poly (vinyl pyrrolidon) (PVP) was used as a capping agent to stabilize the particles and prevent them from agglomeration. The characterization studies were conducted by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle sizes of 1731 nm were obtained by TEM images, which were in good agreement with the XRD results. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands at all temperatures and the absence of organic bands at 873 K. The magnetic properties were demonstrated by a vibrating sample magnetometer (VSM), which displayed super paramagnetic behaviors for the calcined samples. The present study also substantiated that, in ferrites, the values of the quantities that were acquired by VSM, such as the saturation magnetization and coercivity field, are primarily dependent on the methods of preparation of the ferrites. Electron paramagnetic resonance (EPR) spectroscopy showed the existence of unpaired electrons and measured the peak-to-peak line width (Δ Hpp), the resonant magnetic field (Hr), and the g-factor values

Antidepressant effects of crocin and its effects on transcript and protein levels of CREB, BDNF, and VGF in rat hippocampus

BACKGROUND: Antidepressants have been shown to affect levels of brain-derived neurotrophic factor (BDNF) and VGF (non-acronymic) whose transcriptions are dependent on cAMP response element binding protein (CREB) in long term treatment. The aim of this study was to verify the subacute antidepressant effects of crocin, an active constituent of saffron (Crocus sativus L.), and its effects on CREB, BDNF, and VGF proteins, transcript levels and amount of active, phosphorylated CREB (P-CREB) protein in rat hippocampus. METHODS: Crocin (12.5, 25, and 50 mg/kg), imipramine (10 mg/kg; positive control) and saline (1 mL/kg; neutral control) were administered intraperitoneally (IP) to male Wistar rats for 21 days. The antidepressant effects were studied using the forced swimming test (FST) on day 21 after injection. Protein expression and transcript levels of genes in the rat hippocampus were evaluated using western blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. RESULTS: Crocin significantly reduced the immobility time in the FST. Western blot analysis showed that 25 and 50 mg/kg of crocin increased the levels of CREB and BDNF significantly and dose dependently. All doses of crocin increased the VGF levels in a dose-dependent manner. Levels of p-CREB increased significantly by 50 mg/kg dose of crocin. Only 12.5 mg/kg crocin could significantly increase the transcript levels of BDNF. No changes in CREB and VGF transcript levels were observed in all groups. CONCLUSIONS: These results suggest that crocin has antidepressant-like action by increasing CREB, BDNF and VGF levels in hippocampus

Risperidone-Induced Erythema Multiforme Minor: A Case Report

Erythema Multiforme (EM) is a hypersensitivity reaction that can be triggered by an infection or particular medications. Erythema multiforme minor (EM minor) represents localized skin lesions with minimal or no mucosal involvement. Only a few case of EM associated with risperidone are found in the scientific literature. In this case report, the administration of the risperidone resulted in the rapid appearance of skin lesions. Erythematous lesions were recovered upon discontinuation of the drug and no new skin lesion was observed. A 52-year-old male patient was admitted to the psychiatry hospital because of developing schizophrenic symptoms. At the time of admission, risperidone was added to her previous drug regimen. Two weeks later, the patient returned with a complaint of progressively increasing rashes over his body. The patient was diagnosed with EM minor. The prescribed risperidone was discontinued due to its side-effect profile and the patient’s drug regimen was changed entirely to the olanzapine, haloperidol, and topical clobetasol. At one month follow up visit, his skin lesions were satisfactorily controlled

Experimental and theoretical line parameters for self-and H2-broadened transitions in the first overtone band of CO

International audienceIn this study we have re-analyzed high-resolution spectra of pure CO and CO broadened by hydrogen recorded in the spectral range of the first overtone band [1]. Self-and H2-Lorentzian pressure-broadened half-width, pressure-induced shift parameters, line mixing coefficients as well as line centers and intensities were obtained for 48 (P(24) to R(23)) ro-vibrational transitions belonging to the first overtone (2←0) band of 12 C16O at the ambient temperature (~298 K)

Silver nanoparticle fabrication by laser ablation in polyvinyl alcohol solutions

A laser ablation technique is applied for synthesis of silver nanoparticles in different concentrations of polyvinyl alcohol (PVA) aqueous solution. The ablation of high pure silver plate in the solution is carried out by a nanosecond Q-switched Nd:YAG pulsed laser. X-ray diffraction and transmission electron microscopy are implemented to explore the particles sizes. The effects of PVA concentrations on the absorbance of the silver nanoparticles are studied as well, by using a UV-vis spectrophotometer. The preparation process is carried out for deionized water as a reference sample. The comparison of the obtained results with the reference sample shows that the formation efficiency of nanoparticles in PVA is much higher and the sizes of particles are also smaller