1,606 research outputs found

    Plasma theory of the many-electron atom

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    A new approach to the many-electron atom, based on the formal equivalence between the Hartree-Fock equations and a quantum-mechanical generalization of the collisionless Boltzmann (Vlasov) equation, is presented. This equivalence casts the problem into the framework of conventional plasma theory, the Vlasov equation being merely replaced by its quantum-mechanical analog. The quantum Vlasov equation permits a straightforward expansion of the quantum-mechanical phase space distribution function in powers of h. The first step of this expansion, corresponding physically to a classical correlationless plasma obeying Fermi statistics, leads to the Thomas-Fermi model. Successive steps generate quantum and exchange corrections. The method is applied to the case of the "statistical" correlationless atom (or ion), generalized for the first time to arbitrary temperature and nonzero total orbital angular momentum, with quantum and exchange effects being included to order h^2

    Automatic ontology mapping for agent communication

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    Probiotics for preventing acute otitis media in children

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    This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: to assess the effects of probiotics to prevent the occurrence and reduce the severity of acute otitis media in children.</p

    Less than half of the European dietary recommendations for fish consumption are satisfied by national seafood supplies

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    Funding This research was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) under the East of Scotland Bioscience Doctoral Training Partnership (EastBio DTP) [grant number BB/M010996/1]. The research of BdR is supported by the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS). Acknowledgements We thank Dr Niall. G Fallon (University of Aberdeen) for his analytical assistance.Peer reviewedPublisher PD

    Connection between nurse managers’ stress from workload and overall job stress, job satisfaction and practice environment in central hospitals: A cross sectional study.

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    Nurse managers' workload is considered overwhelming and the resources and support insufficient. Stress from workload has adverse psychological and physical effects and impedes strategic, visible and active leadership. This study aimed to examine nurse managers' stress from workload and its associations to overall job stress, job satisfaction and practice environment. A survey comprising the Nursing Context Index was administered to 490 nurse managers in Finnish central hospitals. The study was reported using the STROBE statement. The response rate was 42.7% (n=209). A statistical analysis revealed that almost every fifth nurse manager experienced high stress from workload with connection to higher job stress overall, higher intent to leave the organization, lower job satisfaction overall, personally and professionally, as well as a more negative perception of the practice environment. Nurse managers' jobs require adequate resources, clear division of work and better empowering structures.publishedVersionPeer reviewe

    Rad51 and BRCA2 - New Molecular Targets for Sensitizing Glioma Cells to Alkylating Anticancer Drugs

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    First line chemotherapeutics for brain tumors (malignant gliomas) are alkylating agents such as temozolomide and nimustine. Despite growing knowledge of how these agents work, patients suffering from this malignancy still face a dismal prognosis. Alkylating agents target DNA, forming the killing lesion O6-alkylguanine, which is converted into DNA double-strand breaks (DSBs) that trigger apoptosis. Here we assessed whether inhibiting repair of DSBs by homologous recombination (HR) or non-homologous end joining (NHEJ) is a reasonable strategy for sensitizing glioma cells to alkylating agents. For down-regulation of HR in glioma cells, we used an interference RNA (iRNA) approach targeting Rad51 and BRCA2, and for NHEJ we employed the DNA-PK inhibitor NU7026. We also assessed whether inhibition of poly(ADP)ribosyltransferase (PARP) by olaparib would enhance the killing effect. The data show that knockdown of Rad51 or BRCA2 greatly sensitizes cells to DSBs and the induction of cell death following temozolomide and nimustine (ACNU). It did not sensitize to ionizing radiation (IR). The expression of O6-methylguanine-DNA methyltransferase (MGMT) abolished all these effects, indicating that O6-alkylguanine induced by these drugs is the primary lesion responsible for the formation of DSBs and increased sensitivity of glioma cells following knockdown of Rad51 and BRCA2. Inhibition of DNA-PK only slightly sensitized to temozolomide whereas a significant effect was observed with IR. A triple strategy including siRNA and the PARP inhibitor olaparib further improved the killing effect of temozolomide. The data provides evidence that down-regulation of Rad51 or BRCA2 is a reasonable strategy for sensitizing glioma cells to killing by O6-alkylating anti-cancer drugs. The data also provide proof of principle that a triple strategy involving down-regulation of HR, PARP inhibition and MGMT depletion may greatly enhance the therapeutic effect of temozolomide

    Experimental demonstration of ground state laser cooling with electromagnetically induced transparency

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    Ground state laser cooling of a single trapped ion is achieved using a technique which tailors the absorption profile for the cooling laser by exploiting electromagnetically induced transparency in the Zeeman structure of a dipole transition. This new method is robust, easy to implement and proves particularly useful for cooling several motional degrees of freedom simultaneously, which is of great practical importance for the implementation of quantum logic schemes with trapped ions.Comment: 4 pages, 4 figure

    Augmented feedback approach to double-leg squat training for patients with knee osteoarthritis: a preliminary study

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    The aim of this preliminary study was to explore the effects of two types of augmented feedback on the strategy used by healthy participants and patients with knee osteoarthritis (OA) to perform a double-leg squat. Seven patients with knee OA and seven healthy participants performed three sets of eight double-leg squats: one without feedback, one with real-time kinematic feedback and one with real-time kinetic feedback. Kinematic and kinetic outcome measures (peak knee flexion angle, peak knee extensor moment, and symmetry of the support knee moment between the injured and non-injured knees) demonstrate the potential influence of real-time kinetic feedback on the motor strategy used to perform a double-leg squat in both groups. This feedback could be used to develop more efficient and effective motor strategies for squatting in patients with knee OA and further evaluation is warranted

    Sympathetic ground state cooling and coherent manipulation with two-ion-crystals

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    We have cooled a two-ion-crystal to the ground state of its collective modes of motion. Laser cooling, more specific resolved sideband cooling is performed sympathetically by illuminating only one of the two 40^{40}Ca+^+ ions in the crystal. The heating rates of the motional modes of the crystal in our linear trap have been measured, and we found them considerably smaller than those previously reported by Q. Turchette {\em et. al.} Phys. Rev. A 61, 063418 (2000) in the case of trapped 9^9Be+^+ ions. After the ground state is prepared, coherent quantum state manipulation of the atomic population can be performed. Within the coherence time, up to 12 Rabi oscillations are observed, showing that many coherent manipulations can be achieved. Coherent excitation of each ion individually and ground state cooling are important tools for the realization of quantum information processing in ion traps
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