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91.
We investigate the squeezing properties of a trapped ion in a standing-wave laser. Our results show that the squeezing of a trapped ion in the standing-wave laser is dependent on its position in the latter, the detuning parameter and the initial average phonon number. 相似文献
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Lu Meng Jing Xiang Rupesh Kotecha Douglas Rose Hong Zhao Dazhe Zhao Jinzhu Yang Ton Degrauw 《Magnetic resonance imaging》2010
Background and Purpose
The widespread propagation of synchronized neuronal firing in seizure disorders may affect cortical and subcortical brain regions. Diffusion tensor imaging (DTI) can noninvasively quantify white matter integrity. The purpose of this study was to investigate the abnormal changes of white matter in children and adolescents with focal temporal lobe epilepsy (TLE) using DTI.Materials and Methods
Eight patients with clinically diagnosed TLE and eight age- and sex-matched healthy controls were studied. DTI images were obtained with a 3-T magnetic resonance imaging scanner. The epileptic foci were localized with magnetoencephalography. Fractional anisotropy (FA), mean diffusivity (MD), parallel (λ||) and perpendicular (λ⊥) diffusivities in the genu of the corpus callosum, splenium of the corpus callosum (SCC), external capsule (EC), anterior limbs of the internal capsule (AIC), and the posterior limbs of the internal capsule (PIC) were calculated. The DTI parameters between patients and controls were statistically compared. Correlations of these DTI parameters of each selected structure with age of seizure onset and duration of epilepsy were analysed.Results
In comparison to controls, both patients' seizure ipsilateral and contralateral had significantly lower FA in the AIC; PIC and SCC and higher MD, λ|| and λ⊥ in the EC, AIC, PIC and SCC. The MD, λ|| and λ⊥ were significantly correlated with age of seizure onset in the EC and PIC. λ|| was significantly correlated with the duration of epilepsy in the EC and PIC.Conclusion
The results of the present study indicate that children and adolescents with TLE had significant abnormalities in the white matter in the hemisphere with seizure foci. Furthermore, these abnormalities may extend to the other brain hemisphere. The age of seizure onset and duration of epilepsy may be important factors in determining the extent of influence of children and adolescents TLE on white matter. 相似文献93.
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Yuehan ZHAO;Xiang HAO 《光子学报》2022,51(8):301-313
Due to its simplicity and minimal invasion, light microscopy has been widely applied in biological science, medicine and chemistry. However, as the result of diffraction, the spatial resolution of standard optical microscopy is limited to about half the wavelength of light, with a lateral dimension of around 200~300 nm and an axial dimension of approximately 500~700 nm. This diffraction limits the ability of light microscopy to resolve the subcellular organization of individual molecules or molecular complexes. To overcome the resolution barrier of optical microscopy caused by diffraction limit, a variety of super-resolution microscopy techniques have been developed over the past 15 years, which significantly improved the resolution of light microscopy to 10 nm. These techniques can be roughly classified into two categories： 1） single-molecule localization microscopy such as stochastic optical reconstruction microscopy and photoactivation localization microscopy, and 2） spatially patterned illumination-based methods, such as stimulated emission depletion microscopy and structured illumination microscopy. These techniques have revolutionized our understanding of the nanoscale world, Bringing new opportunities and challenges to molecular-scale biological research.This review summarizes the multicolor single-molecule localization microscopy techniques developed in the past five years from the perspectives of biological sample preparation and optical system improvement, The basic principles of each technique are explained and their advantages and disadvantages are discussed.According to the type of fluorescent probes select during sample preparation, some multicolor SMLM can be classified into three categories： Activator-free SMLM technology using synthetic dyes, which requires fluorophores that exhibit similar blinking efficiency under identical photoswitching buffer conditions. techniques using probes with both an activator and a reporter fluorophore enable multicolor SMLM using different activation lasers. And spectrally selective activation of the reporter fluorophores and multicolor SMLM by repetitive quenching and labelling biological samples.The addition of optical elements allows different wavelengths to be processed according to the spectral information of a fluorophore and multicolor imaging can be realized through data post-processing. These multicolor SMLM methods are mainly divided into three categories： Ratiometric SMLM, spectrally resolved SMLM and methods based on Point-Spread-Function （PSF） engineering.In Ratiometric SMLM, synthetic dyes can be efficiently excited by the same laser wavelength in the same switching buffer, but exhibit different emission peaks. The emission fluorescence is spectrally separated by a dichroic beam splitter and imaged into two parts of the same camera. Spectrally resolved SMLM separate the emission fluorescence of different dyes through a dispersive device, and records the emission spectrum and position information separately. The last method for multicolor single-molecule localization is PSF engineering. Additional optical elements are used to make the PSF shape vary with the depth of the emitter and the wavelength of the fluorophore. The problem with the Ratiometric approach is that the Crosstalk between channels is higher than in the other two methods. However, an outstanding challenge of the last two techniques is the accurate and precise localization of individual point emitters in densely labelled samples.Finally, we present an outlook on the fast-growing field of multicolor single-molecule localization microscopy. One of the future development directions of multicolor single molecules is the research on probes, including the brighter organic fluorescent dyes or fluorescent proteins and more universal imaging buffers. Further research can also be done on reducing the complexity of the optical system and expanding the field of view of imaging. It can be envisioned that multicolor SMLM will play a more prominent role in biological and medical research for many years to come. We hope that this review can help researchers choose the appropriate multicolor SMLM for their own experiments. 相似文献
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AbstractA new C19-diterpenoid alkaloid named hemsleyaline (1), along with fourteen known alkaloids (2-15), were isolated from the roots of Aconitum hemsleyanum Pritz. (Ranunculaceae), a herbal medicine in southwest China. Their structures were established on the basis of extensive spectroscopic analyses. Compound 1 showed mild cholinesterase inhibitory effect with IC50 value of 471?±?9?μM. 相似文献