26,516 research outputs found

    Condensation cyclization reactions of electron deficient aromatics. 4: Tricyclic nitropropene nitronates from the reaction of phloroglucinol and cycloalkanones with sym-trinitrobenzene

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    Interesting similarities have been shown between the reactions of sym-trinitrobenzene with cycloalkanones, and with phloroglucinol. Previously unsuspected common intermediates have been shown to intervene. The structurally similar products in each case are tricyclic nitropropene nitronates. Protonation of these yields the corresponding nitronic acids in certain instances

    An HI survey of the Bootes Void. II. The Analysis

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    We discuss the results of a VLA HI survey of the Bootes void and compare the distribution and HI properties of the void galaxies to those of galaxies found in a survey of regions of mean cosmic density. The Bootes survey covers 1100 Mpc3^{3}, or \sim 1\% of the volume of the void and consists of 24 cubes of typically 2 Mpc * 2 Mpc * 1280 km/s, centered on optically known galaxies. Sixteen targets were detected in HI; 18 previously uncataloged objects were discovered directly in HI. The control sample consists of 12 cubes centered on IRAS selected galaxies with FIR luminosities similar to those of the Bootes targets and located in regions of 1 to 2 times the cosmic mean density. In addition to the 12 targets 29 companions were detected in HI. We find that the number of galaxies within 1 Mpc of the targets is the same to within a factor of two for void and control samples, and thus that the small scale clustering of galaxies is the same in regions that differ by a factor of \sim 6 in density on larger scales. A dynamical analysis of the galaxies in the void suggests that on scales of a few Mpc the galaxies are gravitationally bound, forming interacting galaxy pairs, loose pairs and loose groups. One group is compact enough to qualify as a Hickson compact group. The galaxies found in the void are mostly late-type, gas rich systems. A careful scrutiny of their HI and optical properties shows them to be very similar to field galaxies of the same morphological type. This, combined with our finding that the small scale clustering of the galaxies in the void is the same as in the field, suggests that it is the near environment that mostly affects the evolution of galaxies.Comment: Latex file of abstract. The postscript version of the complete paper (0.2 Mb in gzipped format) including all the figures can be retrieved from http://www.astro.rug.nl:80/~secr/ To appear in the February 1996 issue of the Astronomical Journa

    The Geoff Egan Memorial Lecture 2011. Artefacts, art and artifice: reconsidering iconographic sources for archaeological objects in early modern Europe

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    A first systematic analysis of historic domestic material culture depicted in contemporaneous Western painting and prints, c.1400-1800. Drawing on an extensive data set, the paper proposes to methodologies and hermeneutics for historical analysis and archaeological correspondence

    124-Color Super-resolution Imaging by Engineering DNA-PAINT Blinking Kinetics

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    Optical super-resolution techniques reach unprecedented spatial resolution down to a few nanometers. However, efficient multiplexing strategies for the simultaneous detection of hundreds of molecular species are still elusive. Here, we introduce an entirely new approach to multiplexed super-resolution microscopy by designing the blinking behavior of targets with engineered binding frequency and duration in DNA-PAINT. We assay this kinetic barcoding approach in silico and in vitro using DNA origami structures, show the applicability for multiplexed RNA and protein detection in cells, and finally experimentally demonstrate 124-plex super-resolution imaging within minutes.We thank Martin Spitaler and the imaging facility of the MPI of Biochemistry for confocal imaging support

    Identification of depression in a rural general practice

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    Major depression is underdiagnosed by general practitioners, but the reasons for this are not clear. This study aimed to establish the prevalence of major depression and coexisting generalised anxiety disorder in a rural general practice in the Orange Free State. It also assessed the predictive value of a screening questionnaire for use by general practitioners. The two practitioners evaluated 858 patients over a 4-week period. Those who met the screening criteria, together with a random sample of 60 patients who did not, were re-evaluated by a registrar in psychiatry who was unaware of the findings of his colleagues. Of the patients studied, 134 (15,6%) had major depression; 59 of these (44,0%) also had coexisting generalised anxiety disorder. The general practitioners had . correctly diagnosed major depression in 32 patients (3,7%) before the study started. The screening questionnaire had a 42% chance of correctly identifying a patient with depression and a 97% chance of correctly identifying a patient who did not have major depression. Both practitioners were equally capable at identifying major depression. The study confirmed both the high prevalence of depression in a rural general practice and its low identification rate. It also showed the advantage of using a screening questionnaire to alert practitioners to the possibility of depression in their patients

    Dynamics of few-body states in a medium

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    Strongly interacting matter such as nuclear or quark matter leads to few-body bound states and correlations of the constituents. As a consequence quantum chromodynamics has a rich phase structure with spontaneous symmetry breaking, superconductivity, condensates of different kinds. All this appears in many astrophysical scenarios. Among them is the formation of hadrns during the early stage of the Universe, the structure of a neutron star, the formation of nuclei during a supernova explosion. Some of these extreme conditions can be simulated in heavy ion colliders. To treat such a hot and dense system we use the Green function formalism of many-body theory. It turns out that a systematic Dyson expansion of the Green functions leads to modified few-body equations that are capable to describe phase transitions, condensates, cluster formation and more. These equations include self energy corrections and Pauli blocking. We apply this method to nonrelativistic and relativistic matter. The latter one is treated on the light front. Because of the medium and the inevitable truncation of space, the few-body dynamics and states depend on the thermodynamic parameters of the medium.Comment: 3 pages, 2 figures, talk presented at the 19th European Conference on Few-Body System

    Testing of High Voltage Surge Protection Devices for Use in Liquid Argon TPC Detectors

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    In this paper we demonstrate the capability of high voltage varistors and gas discharge tube arrestors for use as surge protection devices in liquid argon time projection chamber detectors. The insulating and clamping behavior of each type of device is characterized in air (room temperature), and liquid argon (90~K), and their robustness under high voltage and high energy surges in cryogenic conditions is verified. The protection of vulnerable components in liquid argon during a 150 kV high voltage discharge is also demonstrated. Each device is tested for argon contamination and light emission effects, and both are constrained to levels where no significant impact upon liquid argon time projection chamber functionality is expected. Both devices investigated are shown to be suitable for HV surge protection applications in cryogenic detectors.Comment: 22 pages, 18 figures v2: reduced file size for journal submissio
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