243 research outputs found

    Complete intersections and mod p cochains

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    We give homotopy invariant definitions corresponding to three well known properties of complete intersections, for the ring, the module theory and the endomorphisms of the residue field, and we investigate them for the mod p cochains on a space, showing that suitable versions of the second and third are equivalent and that the first is stronger. We are particularly interested in classifying spaces of groups, and we give a number of examples. This paper follows on from arXiv:0906.4025 which considered the classical case of a commutative ring and arXiv:0906.3247 which considered the case of rational homotopy theory.Comment: To appear in AG

    Time resolved anisotropic emission from an aluminium laser produced plasma

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    The polarisation anisotropy of the emission from a laser produced aluminium plasma has been studied using time and polarisation resolved spectroscopy at various background pressures of air. A Wollaston prism was used to resolve the emission from the plasma into polarisation components that are parallel and orthogonal to the plasma expansion axis. Spectroscopy reveals that as the background pressure is increased, strongly polarised continuum emission dominates at early stages of the plasma formation. The results are compared and contrasted to similar experiments and discussed in the framework of a recombining plasma

    Nanoimaging using soft X-ray and EUV laser-plasma sources

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    In this work we present three experimental, compact desk-top imaging systems: SXR and EUV full field microscopes and the SXR contact microscope. The systems are based on laser-plasma EUV and SXR sources based on a double stream gas puff target. The EUV and SXR full field microscopes, operating at 13.8 nm and 2.88 nm wavelengths are capable of imaging nanostructures with a sub-50 nm spatial resolution and short (seconds) exposure times. The SXR contact microscope operates in the "water-window" spectral range and produces an imprint of the internal structure of the imaged sample in a thin layer of SXR sensitive photoresist. Applications of such desk-top EUV and SXR microscopes, mostly for biological samples (CT26 fibroblast cells and Keratinocytes) are also presented. Details about the sources, the microscopes as well as the imaging results for various objects will be presented and discussed. The development of such compact imaging systems may be important to the new research related to biological, material science and nanotechnology applications

    Do risk factors for suicidal behavior differ by affective disorder polarity?

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    BACKGROUND: Suicide is a leading cause of death and has been strongly associated with affective disorders. The influence of affective disorder polarity on subsequent suicide attempts or completions and any differential effect of suicide risk factors by polarity were assessed in a prospective cohort. METHODS: Participants with major affective disorders in the National Institute of Mental Health Collaborative Depression Study were followed prospectively for up to twenty-five years. A total of 909 participants meeting prospective diagnostic criteria for major depressive and bipolar disorders were followed through 4,204 mood cycles. Suicidal behavior was defined as suicide attempts or completions. Mixed-effects, grouped-time survival analysis assessed risk of suicidal behavior and differential effects of risk factors for suicidal behavior by polarity. In addition to polarity, the main effects of age, gender, hopelessness, married status, prior suicide attempts, and active substance abuse were modeled with mood cycle as the unit of analysis. RESULTS: After controlling for age of onset, there were no differences in prior suicide attempts by polarity though bipolar participants had more prior severe attempts. During follow-up, forty cycles ended in suicide and 384 cycles contained at least one suicide attempt. Age, hopelessness, and active substance abuse but not polarity predicted suicidal behavior. The effects of risk factors did not differ by polarity. CONCLUSIONS: Bipolarity does not independently influence risk of suicidal behavior or the influence of well-established suicide risk factors within affective disorders. Suicide risk assessment strategies may continue to appraise these common risk factors without regard to mood polarity

    Laser-produced plasma EUV source based on tin-rich, thin-layer targets

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    In this paper a new approach to a laser-produced plasma EUV source based on a tin target is presented. A thin layer of pure tin and composite layers consisting of Sn with Si, SiO and LiF are investigated. The target composed of several thin layers produces less debris than the other targets and provides a conversion efficiency (CE) in the 13.5-nm +/- 1% band at least comparable to the CE for the pure tin slab target. The largest CE was observed for the target composed of a mixture of Sn and LiF, due to the fact that lithium, similarly to tin, is a strong emitter at 13.5 nm

    Why proanthocyanidins elute at increasing order of molecular masses when analysed by normal phase high performance liquid chromatography? Considerations of use

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    Although it is widely known that proanthocyanidins elute at an increasing order of molecular masses when analysed by normal phase high performance liquid chromatography (NP-HPLC), there is no a consistent explanation of the mechanisms of their separation until now. Therefore, the aim of the present study was to give a reliable response to this question, using a complex procyanidin-rich grape seed extract. For this, an off-column static simulation of extract injection and a fragmented-column dynamic procyanidin location tests were studied to show their precipitation in an aprotic solvent, besides another off-column static simulation and multiple contact dynamic solubilisation tests to confirm procyanidin redissolution in an aprotic/protic solvent system. The results showed that separation of procyanidins in the aprotic/protic solvent system of Diol-NP-HPLC was governed by precipitation/redissolution mechanism, that could be extended to all known plant proanthocyanidin homopolymers, including hydrolysable tannins, if they are able to accomplish this condition. However, separation of monomer species, namely catechins and some hydroxybenzoic acids, was based on classic adsorption/partition mechanism. Other factors, such as analyte solubility, chromatographic conditions and sample preparation, that affect the viability of proanthocyanidin analysis by NP-HPLC were stand out and guidelines for its durable and reproducible use were definedWe thank the Consejería de Educación e Investigación from Comunidad de Madrid Consejería de Ciencia, Universidades e Innovación (ref. IND2019/BIO-17238) for the financial support of this study and the fellow-ship grant of Esperanza Guerrero-Hurtado and contract of Alba Gutiérrez-Doci

    Bioimaging using full field and contact EUV and SXR microscopes with nanometer spatial resolution

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    We present our recent results, related to nanoscale imaging in the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges and demonstrate three novel imaging systems recently developed for the purpose of obtaining high spatial resolution images of nanoscale objects with the EUV and SXR radiations. All the systems are based on laser-plasma EUV and SXR sources, employing a double stream gas puff target. The EUV and SXR full field microscopes—operating at 13.8 nm and 2.88 nm wavelengths, respectively—are currently capable of imaging nanostructures with a sub-50 nm spatial resolution with relatively short (seconds) exposure times. The third system is a SXR contact microscope, operating in the “water-window” spectral range (2.3–4.4 nm wavelength), to produce an imprint of the internal structure of the investigated object in a thin surface layer of SXR light sensitive poly(methyl methacrylate) photoresist. The development of such compact imaging systems is essential to the new research related to biological science, material science, and nanotechnology applications in the near future. Applications of all the microscopes for studies of biological samples including carcinoma cells, diatoms, and neurons are presented. Details about the sources, the microscopes, as well as the imaging results for various objects will be shown and discussed

    New perspectives for eye-sparing treatment strategies in primary uveal melanoma

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    Uveal melanoma is the most common intraocular malignancy and arises from melanocytes in the choroid, ciliary body, or iris. The current eye-sparing treatment options include surgical treatment, plaque brachytherapy, proton beam radiotherapy, stereotactic photon radiotherapy, or photodynamic therapy. However, the efficacy of these methods is still unsatisfactory. This article reviews several possible new treatment options and their potential advantages in treating localized uveal melanoma. These methods may be based on the physical destruction of the cancerous cells by applying ultrasounds. Two examples of such an approach are High-Intensity Focused Ultrasound (HIFU)—a promising technology of thermal destruction of solid tumors located deep under the skin and sonodynamic therapy (SDT) that induces reactive oxygen species. Another approach may be based on improving the penetration of anti-cancer agents into UM cells. The most promising technologies from this group are based on enhancing drug delivery by applying electric current. One such approach is called transcorneal iontophoresis and has already been shown to increase the local concentration of several different therapeutics. Another technique, electrically enhanced chemotherapy, may promote drug delivery from the intercellular space to cells. Finally, new advanced nanoparticles are developed to combine diagnostic imaging and therapy (i.e., theranostics). However, development. these methods More are mostly advanced at an and early targeted stage of preclinical development. studies More and advanced clinical trials and targeted would be preclinical needed to studies introduce and some clinical of trials these would techniques be needed to routine to introduce clinical practice. some of these techniques to routine clinical practice
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