2,588 research outputs found

    A transportable strontium optical lattice clock

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    We report on a transportable optical clock, based on laser-cooled strontium atoms trapped in an optical lattice. The experimental apparatus is composed of a compact source of ultra-cold strontium atoms including a compact cooling laser set-up and a transportable ultra-stable laser for interrogating the optical clock transition. The whole setup (excluding electronics) fits within a volume of less than 2 m3^3. The high degree of operation reliability of both systems allowed the spectroscopy of the clock transition to be performed with 10 Hz resolution. We estimate an uncertainty of the clock of 7×10157\times10^{-15}.Comment: 12 pages, 9 figures, to be published in Appl. Phys.

    Two cases of feline pyothorax : medical versus surgical treatment and associated challenges

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    Pyothorax is a rare disease in cats. Underlying causes and treatment recommendations vary greatly between cases. In this case series, the management of two challenging cases of feline pyothorax is discussed. In the first case, a nine-year-old female spayed European shorthair cat with pyothorax caused by Bacteroides fragilis is described. At the time of presentation, she was diagnosed with feline immunodeficiency virus as well. The pyothorax was succesfully managed medically. Unfortunately, the cat relapsed after three months and the owner elected euthanasia. The second case involved a ten-year-old male castrated British shorthair cat with identification of filamentous bacteria on pleural fluid cytology. This cat underwent surgical intervention because thoracic drainage was very difficult. Eventually, he recovered well and did not relapse up to two months postoperatively. The challenges in the decision process and treatment complications are discussed

    Analyzing runtime and size complexity of integer programs

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    We present a modular approach to automatic complexity analysis of integer programs. Based on a novel alternation between finding symbolic time bounds for program parts and using these to infer bounds on the absolute values of program variables, we can restrict each analysis step to a small part of the program while maintaining a high level of precision. The bounds computed by our method are polynomial or exponential expressions that depend on the absolute values of input parameters. We show how to extend our approach to arbitrary cost measures, allowing to use our technique to find upper bounds for other expended resources, such as network requests or memory consumption. Our contributions are implemented in the open source tool KoAT, and extensive experiments show the performance and power of our implementation in comparison with other tools

    Pyothorax in cats and dogs

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    Pyothorax, or thoracic empyema, is an infection of the pleural space, characterized by the accumulation of purulent exudate. It is a life-threatening emergency in dogs as well as in cats, with a guarded prognosis. Dyspnea and/or tachypnea, anorexia and lethargy are the most typical clinical signs. Diagnosis is usually straightforward, based on the clinical symptoms combined with pleural fluid analysis, including cytology and bacterial culture. Most commonly, oropharyngeal flora is isolated in the pleural fluid. Treatment can be medical or surgical, but needs to be immediate and aggressive. In this article, an overview of the various causes of both feline and canine pyothorax with its similarities and differences is provided. Epidemiology, symptoms, diagnosis, treatment and prognosis are discussed

    Chemotaxis Receptor Complexes: From Signaling to Assembly

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    Complexes of chemoreceptors in the bacterial cytoplasmic membrane allow for the sensing of ligands with remarkable sensitivity. Despite the excellent characterization of the chemotaxis signaling network, very little is known about what controls receptor complex size. Here we use in vitro signaling data to model the distribution of complex sizes. In particular, we model Tar receptors in membranes as an ensemble of different sized oligomer complexes, i.e., receptor dimers, dimers of dimers, and trimers of dimers, where the relative free energies, including receptor modification, ligand binding, and interaction with the kinase CheA determine the size distribution. Our model compares favorably with a variety of signaling data, including dose-response curves of receptor activity and the dependence of activity on receptor density in the membrane. We propose that the kinetics of complex assembly can be measured in vitro from the temporal response to a perturbation of the complex free energies, e.g., by addition of ligand

    NEOTωIST: A relatively Inexpensive Kinetic Impactor Demonstration Mission Concept

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    Mission concept: NEOTωIST stands for Near-Earth Object Transfer of angular momentum (ω∙I) Spin Test, and is a concept for a kinetic impactor demonstration mission, which aims to change the spin rate of an asteroid by impacting it off-center (Drube et al. 2016, Engel et al. 2016). The change would be measured by means of lightcurve measurements with Earth-based telescopes. In contrast to most other kinetic impactor demonstration mission concepts, NEOTωIST does not require a reconnaissance spacecraft to rendezvous with the target asteroid for orbit change and impact-effect measurements, and is therefore a relatively inexpensive alternative. The NEOTωIST mission would determine the efficiency of momentum transfer (the β-factor) during an impact, and help mature the technology required for a kinetic impactor mission, both of which are important precursor measures for a future space mission to deflect an asteroid by collisional means in an emergency impact hazard situation
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