1,178 research outputs found

    The Cause of Photospheric and Helioseismic Responses to Solar Flares: High-Energy Electrons or Protons?

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    Analysis of the hydrodynamic and helioseismic effects in the photosphere during the solar flare of July 23, 2002, observed by Michelson Doppler Imager (MDI) on SOHO, and high-energy images from RHESSI shows that these effects are closely associated with sources of the hard X-ray emission, and that there are no such effects in the centroid region of the flare gamma-ray emission. These results demonstrate that contrary to expectations the hydrodynamic and helioseismic responses (''sunquakes") are more likely to be caused by accelerated electrons than by high-energy protons. A series of multiple impulses of high-energy electrons forms a hydrodynamic source moving in the photosphere with a supersonic speed. The moving source plays a critical role in the formation of the anisotropic wave front of sunquakes.Comment: 13 pages, 5 figures, ApJL in pres

    Enhancing the biocompatibility of rhodamine fluorescent probes by a neighbouring group effect

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    Fluorescence microscopy is an essential tool for understanding dynamic processes in living cells and organisms. However, many fluorescent probes for labelling cellular structures suffer from unspecific interactions and low cell permeability. Herein, we demonstrate that the neighbouring group effect which results from positioning an amide group next to a carboxyl group in the benzene ring of rhodamines dramatically increases cell permeability of the rhodamine-based probes through stabilizing a fluorophore in a hydrophobic spirolactone state. Based on this principle, we create probes targeting tubulin, actin and DNA. Their superb staining intensity, tuned toxicity and specificity allows long-term 3D confocal and STED nanoscopy with sub-30 nm resolution. Due to their unrestricted cell permeability and efficient accumulation on the target, the new probes produce high contrast images at low nanomolar concentrations. Superior performance is exemplified by resolving the real microtubule diameter of 23 nm and selective staining of the centrosome inside living cells for the first time

    Stratospheric sounding by infrared heterodyne spectroscopy

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    Intensity profiles of infrared spectral lines of stratospheric constituents can be fully resolved with a heterodyne spectrometer of sufficiently high resolution. The constituents' vertical distributions can then be evaluated accurately by analytic inversion of the measured line profiles. Estimates of the detection sensitivity of a heterodyne receiver are given in terms of minimum detectable volume mixing ratios of stratospheric constituents, indicating a large number of minor constituents which can be studied. Stratospheric spectral line shapes, and the resolution required to measure them are discussed in light of calculated synthetic line profiles for some stratospheric molecules in a model atmosphere. The inversion technique for evaluation of gas concentration profiles is briefly described and applications to synthetic lines of O3, CO2, CH4 and N2O are given

    Blinking fluorescent probes for tubulin nanoscopy in living and fixed cells

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    Here we report a small molecule tubulin probe for single-molecule localization microscopy (SMLM), stimulated emission depletion (STED) microscopy and MINFLUX nanoscopy, which can be used in living and fixed cells. We explored a series of taxane derivatives containing spontaneously blinking far-red dye hydroxymethyl silicon–rhodamine (HMSiR) and found that the linker length profoundly affects the probe permeability and off-targeting in living cells. The best performing probe, HMSiR-tubulin, is composed of cabazitaxel and the 6′-regioisomer of HMSiR bridged by a C6 linker. Microtubule diameter of ≤50 nm was routinely measured in SMLM experiments on living and fixed cells. HMSiR-tubulin allows a complementary use of different nanoscopy techniques for investigating microtubule functions and developing imaging methods. For the first time, we resolved the inner microtubule diameter of 16 ± 5 nm by optical nanoscopy and thereby demonstrated the utility of a self-blinking dye for MINFLUX imaging

    Дослідження сучасних підходів до формування асортиментної політики вітчизняних фармацевтичних підприємств

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    The article summarizes the current approaches to formation of the assortment policy of the manufacturing pharmaceutical companies. The classification of methods of the assortment policy formation for a manufacturing company has been carried out. The specific features of the assortment policy formation of the leading domestic pharmaceutical manufacturers have been analyzed. It has been determined that the combination of several assortment strategies in the company’s work promotes formation of the best assortment policy.В статье обобщены современные подходы к формированию ассортиментной политики производственных фармацевтических предприятий. Осуществлена классификация методов формирования ассортиментной политики промышленного предприятия. Проанализированы особенности формирования ассортиментной политики ведущих отечественных фармацевтических производителей. Установлено, что формированию самой выгодной ассортиментной политики способствует сочетание нескольких ассортиментных стратегий в работе предприятия.У статті узагальнено сучасні підходи до формування асортиментної політики виробничих фармацевтичних підприємств. Здійснено класифікацію методів формування асортиментної політики промислового підприємства. Проаналізовано особливості формування асортиментної політики провідних вітчизняних фармацевтичних виробників. Встановлено, що формуванню найвигіднішої асортиментної політики сприяє поєднання кількох асортиментних стратегій у роботі підприємства

    Towards an Imaging Mid-Infrared Heterodyne Spectrometer

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    We are developing a concept for a compact, low-mass, low-power, mid-infrared (MIR; 5- 12 microns) imaging heterodyne spectrometer that incorporates fiber optic coupling, Quantum Cascade Laser (QCL) local oscillator, photomixer array, and Radio Frequency Software Defined Readout (RFSDR) for spectral analysis. Planetary Decadal Surveys have highlighted the need for miniaturized, robust, low-mass, and minimal power remote sensing technologies for flight missions. The drive for miniaturization of remote sensing spectroscopy and radiometry techniques has been a continuing process. The advent of MIR fibers, and MEMS techniques for producing waveguides has proven to be an important recent advancement for miniaturization of infrared spectrometers. In conjunction with well-established photonics techniques, the miniaturization of spectrometers is transitioning from classic free space optical systems to waveguide/fiber-based structures for light transport and producing interference effects. By their very nature, these new devices are compact and lightweight. Mercury-Cadmium-Telluride (MCT) and Quantum Well Infrared Photodiodes (QWIP) arrays for heterodyne applications are also being developed. Bulky electronics is another barrier that precluded the extension of heterodyne systems into imaging applications, and our RFSDR will address this aspect

    Discovery of natural gain amplification in the 10 muon m CO2 laser bands on Mars: The first definite natural laser

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    Fully resolved intensity profiles of various lines in the CO2 bands at 9.4 micrometers and 10.4 micrometers were measured on Mars using an infrared heterodyne spectrometer. Analysis of the line shapes shows that the Mars atmosphere exhibits positive gain on these lines, providing the first definite detection of natural optical gain amplification and enabling identification of these lines as the first definite natural laser ever discovered

    Stratospheric ozone measurement with an infrared heterodyne spectrometer

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    A stratospheric ozone absorption line in the 10 microns band was measured and resolved completely, using an infrared heterodyne spectrometer with spectral resolution of 5 MHz (0.000167 cm to -1 power). The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectral line profile. The absolute total column density was 0.34 cm atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) to (7,1,7) O3 line center frequency was found to be 1043.1775 + or - 0.00033 cm to toe -1 power, or 430 + or - 10 MHz higher than the P(24) CO2 laser line frequency
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