نتایج جستجو برای: spectroscopic
تعداد نتایج: 46257 فیلتر نتایج به سال:
NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in por...
Multilayer epitaxial graphene is investigated using far infrared transmission experiments in the different limits of low magnetic fields and high temperatures. The cyclotron-resonance-like absorption is observed at low temperature in magnetic fields below 50 mT, probing the nearest vicinity of the Dirac point. The carrier mobility is found to exceed 250,000 cm2/(V x s). In the limit of high tem...
The high-fidelity reconstruction of compressed and low-resolution magnetic resonance (MR) data is essential for simultaneously improving patient care, accuracy in diagnosis and quality in clinical research. Sponsored by the Royal Society through the Newton Mobility Grant Scheme, we held a half-day workshop on reconstruction schemes for MR data on 17 August 2016 to discuss new ideas from related...
Recent research in brain imaging has highlighted the role of different neural networks in the resting state (ie, no task) in which the brain displays spontaneous low-frequency neuronal oscillations. These can be indirectly measured with resting-state functional magnetic resonance imaging, and functional connectivity can be inferred as the spatiotemporal correlations of this signal. This techniq...
We demonstrate a Doppler-free spectroscopic method that we test on Rb and Rb vapor. By using a magnetic field to induce a dichroism on the sample, we generate a dispersive signal with low background, which allows us to lock a diode laser even on small spectroscopic features. We elaborate the advantages of this simple and easy method by comparing it to other methods. PACS. 39.30.+w Spectroscopic...
OBJECTIVE This review is a primer on the technical aspects of performing a high-quality MRI and MR spectroscopic imaging examination of the prostate. CONCLUSION MRI and MR spectroscopic imaging are useful tools in the localization, staging, and functional assessment of prostate cancer. Performing a high-quality MR spectroscopic examination requires understanding of the technical aspects and l...
Fast multiple spin-echo spectroscopic imaging, also called turbo spectroscopic imaging (TSI), may be enhanced in terms of acquisition speed by taking advantage of the higher spectral separation afforded at higher field strength and by further combining it with sensitivity encoding (SENSE). This article demonstrates the possibilities of this approach at 3T, resulting in scan-time reductions of u...
A blood pre-centrifugation delay of 24 h at room temperature influenced the proton NMR spectroscopic profiles of human serum. A blood pre-centrifugation delay of 24 h at 4°C did not influence the spectroscopic profile as compared with 4 h delays at either room temperature or 4°C. Five or ten serum freeze-thaw cycles also influenced the proton NMR spectroscopic profiles. Certain common in vitro ...
From the aerial parts of Tanacetum balsamita L. (Compositae) a flavonol aglycon was isolated using chromatographic techniques. The structure of this compound was determined using spectroscopic methods (UV, H-NMR and MS) as 3',4',5,7-Tetrahydroxy flavonol (Quercetin).
Currently, images acquired via magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) technology are reconstructed using the discrete inverse Fourier transform. While computationally convenient, this approach is not able to filter out noise. This is a serious limitation because the amount of noise in MRI and fMRI can be substantial. In this paper, we propose an altern...
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