701 research outputs found

    Large Charge Four-Dimensional Extremal N=2 Black Holes with R^2-Terms

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    We consider N=2 supergravity in four dimensions with small R^2 curvature corrections. We construct large charge extremal supersymmetric and non-supersymmetric black hole solutions in all space, and analyze their thermodynamic properties.Comment: 18 pages. v2,3: minor fixe

    Large Charge Four-Dimensional Non-Extremal N=2 Black Holes with R^2-Terms

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    We consider N=2 supergravity in four dimensions with small R^2 curvature corrections. We construct large charge non-extremal black hole solutions in all space, with either a supersymmetric or a non-supersymmetric extremal limit, and analyze their thermodynamic properties. This generalizes some of the extremal solutions presented in [arXiv:0902.0831]. The indexed entropy of the non-extremal extension of the supersymmetric black hole, has the form of the extremal entropy, with the charges replaced by a function of the charges, the moduli at infinity and the non-extremality parameter. This is the same behavior as in the case without R^2-terms.Comment: 13 pages. v2: stripped down to letter format, based on the background given in [arXiv:0902.0831]. v3: up to date with CQG versio

    Backward Evolving Quantum States

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    The basic concept of the two-state vector formalism, which is the time symmetric approach to quantum mechanics, is the backward evolving quantum state. However, due to the time asymmetry of the memory's arrow of time, the possible ways to manipulate a backward evolving quantum state differ from those for a standard, forward evolving quantum state. The similarities and the differences between forward and backward evolving quantum states regarding the no-cloning theorem, nonlocal measurements, and teleportation are discussed. The results are relevant not only in the framework of the two-state vector formalism, but also in the framework of retrodictive quantum theory.Comment: Contribution to the J.Phys. A special issue in honor of GianCarlo Ghirard

    Pre- and post-selection, weak values, and contextuality

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    By analyzing the concept of contextuality (Bell-Kochen-Specker) in terms of pre-and-post-selection (PPS), it is possible to assign definite values to observables in a new and surprising way. Physical reasons are presented for restrictions on these assignments. When measurements are performed which do not disturb the pre- and post-selection (i.e. weak measurements), then novel experimental aspects of contextuality can be demonstrated including a proof that every PPS-paradox with definite predictions implies contextuality. Certain results of these measurements (eccentric weak values with e.g. negative values outside the spectrum), however, cannot be explained by a "classical-like" hidden variable theory.Comment: Identical content; stream-lined verbal presentatio

    A Review to Weigh the Pros and Cons of Online, Remote, and Distance Science Laboratory Experiences

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    The effectiveness of traditional face to face labs versus non-traditional online, remote, or distance labs is difficult to assess due to the lack of continuity in the literature between terminology, standard evaluation metrics, and the use of a wide variety non-traditional laboratory experience for online courses. This narrative review presents a representative view of the existing literature in order to identify the strengths and weaknesses of non-traditional laboratories and to highlight the areas of opportunity for research. Non-traditional labs are increasingly utilized in higher education. The research indicates that these non-traditional approaches to a science laboratory experience are as effective at achieving the learning outcomes as traditional labs. While this is an important parameter, this review outlines further important considerations such as operating and maintenance cost, growth potential, and safety. This comparison identifies several weaknesses in the existing literature. While it is clear that traditional labs aid in the development of practical and procedural skills, there is a lack of research exploring if non-traditional laboratory experiments hinder student success in subsequent traditional labs. Additionally, remote lab kits blur the lines between modality by bringing experiences that are more tactile to students outside of the traditional laboratory environment. Though novel work on non-traditional labs continues to be published, investigations are still needed regarding cost differences, acquisition of procedural skills, preparation for advanced work, and instructor contact time between traditional and non-traditional laboratories

    Undergraduate Research for Online Students

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    Since the term “high impact educational prac-tices” (HIPs) was coined in 2008, it comes up often in SoTL research and professional devel-opment. Undergraduate research is one of the commonly listed HIPs. The profes sional and personal benefits to studentsP are numerous, including increased perAsistence, self-confi-dence, career preparation, enhanced mentori©ng relationships, development of transferable skills, networking opportunities, and balancing of intellectual independence and collaboration skills (Council on Undergraduate Research, 2017; Lopatto, 2006, 2010; Madan & Teitge, 2013)

    Aurora kinase A drives the evolution of resistance to third-generation EGFR inhibitors in lung cancer.

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    Although targeted therapies often elicit profound initial patient responses, these effects are transient due to residual disease leading to acquired resistance. How tumors transition between drug responsiveness, tolerance and resistance, especially in the absence of preexisting subclones, remains unclear. In epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma cells, we demonstrate that residual disease and acquired resistance in response to EGFR inhibitors requires Aurora kinase A (AURKA) activity. Nongenetic resistance through the activation of AURKA by its coactivator TPX2 emerges in response to chronic EGFR inhibition where it mitigates drug-induced apoptosis. Aurora kinase inhibitors suppress this adaptive survival program, increasing the magnitude and duration of EGFR inhibitor response in preclinical models. Treatment-induced activation of AURKA is associated with resistance to EGFR inhibitors in vitro, in vivo and in most individuals with EGFR-mutant lung adenocarcinoma. These findings delineate a molecular path whereby drug resistance emerges from drug-tolerant cells and unveils a synthetic lethal strategy for enhancing responses to EGFR inhibitors by suppressing AURKA-driven residual disease and acquired resistance

    Determining the Concentrations of Trace Metals in Caffeinated Beverages by ICP-AES

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    A myriad of different caffeinated beverages are advertised and readily available to consumers. Previous research has identified the presence of elevated levels of metals unsafe for consumption in many of these beverages, energy drinks in particularly. We aim to analyze concentrations of chromium, aluminum, and lead, three such metals, in a variety of different caffeinated beverages. A calibration curve relating concentration of chromium, lead and aluminum to corrected peak height for five solutions of standardized concentration was created using a ThermoFisher iCAP 6000 Series. The same instrument was then used to analyze samples of eight different caffeinated beverages. The corrected peak heights of each metal in each beverage was collected. Using these values in conjunction with the equation corresponding to the relationship between concentration and peak height, the concentration of each metal contained in the eight samples was calculated. The resulting concentrations were compared with both literature findings and safety regulations relating to metal concentrations in consumer products
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