414 research outputs found

    Wisseling van stof

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    Solar Magnetic Carpet I: Simulation of Synthetic Magnetograms

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    This paper describes a new 2D model for the photospheric evolution of the magnetic carpet. It is the first in a series of papers working towards constructing a realistic 3D non-potential model for the interaction of small-scale solar magnetic fields. In the model, the basic evolution of the magnetic elements is governed by a supergranular flow profile. In addition, magnetic elements may evolve through the processes of emergence, cancellation, coalescence and fragmentation. Model parameters for the emergence of bipoles are based upon the results of observational studies. Using this model, several simulations are considered, where the range of flux with which bipoles may emerge is varied. In all cases the model quickly reaches a steady state where the rates of emergence and cancellation balance. Analysis of the resulting magnetic field shows that we reproduce observed quantities such as the flux distribution, mean field, cancellation rates, photospheric recycle time and a magnetic network. As expected, the simulation matches observations more closely when a larger, and consequently more realistic, range of emerging flux values is allowed (4e16 - 1e19 Mx). The model best reproduces the current observed properties of the magnetic carpet when we take the minimum absolute flux for emerging bipoles to be 4e16 Mx. In future, this 2D model will be used as an evolving photospheric boundary condition for 3D non-potential modeling.Comment: 33 pages, 16 figures, 5 gif movies included: movies may be viewed at http://www-solar.mcs.st-and.ac.uk/~karen/movies_paper1

    F-19-nanoparticles: platform for in vivo delivery of fluorinated biomaterials for F-19-MRI

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    Fluorine-19 (F-19) magnetic resonance imaging (MRI) features one of the most investigated and innovative techniques for quantitative and unambiguous cell tracking, providing information for both localization and number of cells. Because of the relative insensitivity of the MRI technique, a high number of magnetically equivalent fluorine atoms are required to gain detectable signals. However, an increased amount of F-19 nuclei induces low solubility in aqueous solutions, making fluorine-based probes not suitable for in vivo imaging applications. In this context, nanoparticle-based platforms play a crucial role, since nanoparticles may carry a high payload of F-19-based contrast agents into the relevant cells or tissues, increase the imaging agents biocompatibility, and provide a highly versatile platform. In this review, we present an overview of the F-19-based nanoprobes for sensitive F-19-MRI, focusing on the main nanotechnologies employed to date, such as fluorine and theranostic nanovectors, including their design and applications.Cardiovascular Aspects of Radiolog

    Cardiorenal syndrome: emerging role of medical imaging for clinical diagnosis and management

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    Cardiorenal syndrome (CRS) concerns the interconnection between heart and kidneys in which the dysfunction of one organ leads to abnormalities of the other. The main clinical challenges associated with cardiorenal syndrome are the lack of tools for early diagnosis, prognosis, and evaluation of therapeutic effects. Ultrasound, computed tomography, nuclear medicine, and magnetic resonance imaging are increasingly used for clinical management of cardiovascular and renal diseases. In the last decade, rapid development of imaging techniques provides a number of promising biomarkers for functional evaluation and tissue characterization. This review summarizes the applicability as well as the future technological potential of each imaging modality in the assessment of CRS. Furthermore, opportunities for a comprehensive imaging approach for the evaluation of CRS are defined.Cardiovascular Aspects of Radiolog

    Borderline Q-waves in individuals without overt cardiovascular disease: relations with adiposity, subclinical atherosclerosis and vascular stiffness

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    Background: Characteristics and risk factors associated with electrocardiographic borderline Q-waves are not fully elucidated, especially in individuals without overt cardiovascular disease (CVD). Also, the relation of isolated and non-isolated borderline Q-waves with subclinical atherosclerosis and vascular stiffness is unknown. Methods and results: We included 5746 Netherlands Epidemiology of Obesity study participants without overt CVD. Participants were divided in three groups: no Q-waves (93.7%), isolated (4.6%) and non-isolated borderline Q-waves (1.7%). Borderline Q-waves were defined as Minnesota Codes 1.2.x and 1.3.x and non-isolated as ≥1 of abnormal QRS axis, left ventricular hypertrophy or ST/T abnormalities. Several characteristics and measures of body fat were assessed. Vascular stiffness was assessed by pulse wave velocity (PWV) and subclinical atherosclerosis by carotid intima-media thickness (cIMT). Percentage of men, alcohol intake, blood pressure and fasting glucose concentrations were, compared with no Q-waves, higher in the isolated and highest in the non-isolated borderline Q-wave group. Isolated borderline Q-waves were associated with higher body mass index (difference compared with no Q-waves: 1.0 kg/m2; 95%CI: 0.3–1.7; p-value: 0.006), waist circumference (3.4 cm; 1.0–5.8; 0.005), and visceral adipose tissue (21.9 cm2; 7.4–36.3; 0.003) and differences were even larger for non-isolated borderline Q-waves. Compared with no Q-waves, non-isolated borderline Q-waves were associated with higher PWV (1.2 m/s; 0.4–2.0; 0.004) and cIMT (23.4 μm; 3.0–43.8; 0.024), whereas isolated borderline Q-waves were not. Conclusion: Cardiovascular risk factors and measures of body fat, especially abdominal adiposity, were higher in participants with isolated borderline Q-waves, compared with no Q-waves, and highest in the non-isolated borderline Q-wave group. Non-isolated borderline Q-waves were associated with subclinical atherosclerosis and vascular stiffness. Future studies should investigate potential added value of borderline Q-waves in CVD prediction

    4D flow MRI of type B dissection with later retrograde progression to type A dissection in Marfan: a case report

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    Background Due to the malfunction of connective tissue, Marfan patients are at increased risk of aortic dissection. Uncomplicated acute type B dissection is usually managed with medical therapy. Retrograde progression or new type A dissection is a relatively rare but often fatal complication that occur most frequently in the first 6 months after acute type B dissection.Case summary We present a 31-year-old male with Marfan syndrome and a recent uncomplicated type B dissection from the left subclavian to the right common iliac artery who underwent 4D flow magnetic resonance imaging (MRI). The dissection had a large proximal intimal tear just distal to the left subclavian artery (15 mm) and large false lumen (35 mm). Aortic blood flow just distal to the left subclavian artery (3.6 L/min) was split disproportionately into the true (0.8 L/min, 22%) and false lumen (2.8 L/min, 78%). 4D flow streamlines revealed vortical flow in the proximal false lumen. Increased wall shear stress was observed at the sinotubular junction (STJ), inner wall of the ascending aorta and around the subclavian artery. Two weeks after MRI, the patient presented with jaw pain. Computed tomography showed a type A dissection with an entry tear at the STJ for which an acute valve-sparing root, ascending and arch replacement was performed.Discussion Better risk assessment of life-threatening complications in uncomplicated type B dissections could improve treatment strategies in these patients. Our case demonstrates that besides clinical and morphological parameters, flow derived parameters could aid in improved risk assessment for retrograde progression from uncomplicated type B dissection to acute type A dissection.Cardiolog

    Transcriptome profiling on the response of Mycosphaerella graminicola isolates to an azole fungicide using cDNA arrays

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    Resistance to azole antifungals is a major problem in the control of diseases caused by fungal pathogens of both humans and plants. Potential for the development of azole resistance in the wheat leaf blotch pathogen Mycosphaerella graminicola, the causal agent of the most economically significant foliar disease of wheat in north-western Europe, is now of particular concern after the recent emergence of widespread resistance to quinone outside inhibitor fungicides. Using a cDNA microarray representing around 25% of the genome, we have profiled the transcriptional response of M. graminicola to epoxiconazole, currently the most widely used azole fungicide on cereal crops. By comparing the transcription profiles of two M. graminicola isolates with contrasting sensitivities to epoxiconazole we show qualitative and quantitative differences in differentially expressed genes, including those involved in ergosterol biosynthesis, mitochondrial respiration and transport mechanisms. This represents the first study investigating the response of a plant pathogenic fungus to a fungicide using cDNA microarray technology

    COVID-19 associated perimyocarditis

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    Perimyocarditis is a well-known acute inflammation of the pericardium and the underlying myocardium. Most commonly perimyocarditis is of viral aetiology, specifically the coxsackie B virus. However, nowadays SARSCoV-2 associated with COVID-19 infections has emerged as a potential rare cause of perimyocarditis. This case report will demonstrate a case of a young female with perimyocarditis as diagnosed by magnetic resonance imaging (MRI) accompanied by antigens indicating a past COVID-19 infection. Clinical status as well as Findings at MRI, echocardiography and lab results will be reviewed.Cardiolog
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