527 research outputs found

    Atom--Molecule Coherence in a Bose-Einstein Condensate

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    Coherent coupling between atoms and molecules in a Bose-Einstein condensate (BEC) has been observed. Oscillations between atomic and molecular states were excited by sudden changes in the magnetic field near a Feshbach resonance and persisted for many periods of the oscillation. The oscillation frequency was measured over a large range of magnetic fields and is in excellent quantitative agreement with the energy difference between the colliding atom threshold energy and the energy of the bound molecular state. This agreement indicates that we have created a quantum superposition of atoms and diatomic molecules, which are chemically different species.Comment: 7 pages, 6 figure

    Interactive Actor Analysis for Rural Water Management in The Netherlands

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    Recent developments in the policy sciences emphasize the social environment in which decisions are made. The ‘network metaphor’ is often used to describe the key role of interactions between interdependent actors involved in decision making. These interactions take place in a policy arena drawn up by actors with an interest in and control over decisions on the issues addressed. Interdependencies, caused by the need for actors to increase their means of realizing objectives, are the driving force behind these interactions. Dependency relations are of special interest to water management and river basin management because of the fundamental asymmetrical interdependencies that exist in river basins between upstream and downstream stakeholders. Coleman’s linear system of action models decision making process involving dependencies between multiple stakeholders as exchange of control over issues, while interactions are required to negotiate exchanges of control. We developed an interactive method for actor analysis based on Coleman’s linear system of action and applied it to the national rural water management policy domain in The Netherlands. The method is firmly rooted in mathematical sociology and defies the criticism that methods for actor and stakeholder analysis do not specify a theoretical basis explaining the causal relations between the variables analyzed and policy change. With the application to the rural water management policy arena we intended to increase our insight into the practical applicability of this analyticmethod in an interactive workshop, the acceptability of the approach for the participating actors, its contribution to the process of decision making and our understanding of the rural water management policy arena in The Netherlands. We found that the Association of Water Authorities, the Ministry of Public Works and the Ministry of Agriculture are the most powerful actor in the policy domain, while governance and cost and benefits of rural water management are the most salient issues. Progress in policy development for rural water management is probably most promising for the issues governance, costs and benefits, safety and rural living conditions through improved interaction between the Association of Water Authorities, the Ministry of Agriculture and the Rural Credit Bank. Besides these analytic results the interactive approach implemented increased the participants understanding of their dependency on other actors in the rural water management policy domain and supported them in developing a sound perspective on their dependency position. We concluded that the method developed is acceptable to real-world policy decision makers, can successfully be applied in an interactive setting, potentially contributes to the process of decision making by increasing the participants understanding of their dependency position, has the potential to delivers valuable advice for future decision-making and increases our understanding of policy development for rural water management in general

    Evidence based medicine as science

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    Evidence based medicine has claimed to be science on a number of occasions but it is not clear that this status is deserved. Within philosophy of science four main theories about the nature of science are historically recognised: inductivism, falsificationism, Kuhnian paradigms and research programmes. If evidence based medicine is science knowledge claims should be derived using a process that corresponds to one of these theories. This paper analyses whether this is the case. In the first section, different theories about the nature of science are introduced. In the second section, the claim that evidence based medicine is science is reinterpreted as the claim that knowledge claims derived from randomised controlled trails and meta-analyses are science. In the third section the knowledge claims valued within evidence based medicine are considered from the perspective of inductivism, falsificationism, Kuhnian paradigms and research programmes. In the final section possible counter arguments are considered. It is argued that the knowledge claims valued by evidence based medicine are not justified using inductivism, falsificationism, Kuhnian paradigms or research programmes. If these are the main criteria for evaluating if something is science or not, evidence based medicine does not meet these criteria

    A review of wearable motion tracking systems used in rehabilitation following hip and knee replacement

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    Clinical teams are under increasing pressure to facilitate early hospital discharge for total hip replacement and total knee replacement patients following surgery. A wide variety of wearable devices are being marketed to assist with rehabilitation following surgery. A review of wearable devices was undertaken to assess the evidence supporting their efficacy in assisting rehabilitation following total hip replacement and total knee replacement. A search was conducted using the electronic databases including Medline, CINAHL, Cochrane, PsycARTICLES, and PubMed of studies from January 2000 to October 2017. Five studies met the eligibility criteria, and all used an accelerometer and a gyroscope for their technology. A review of the studies found very little evidence to support the efficacy of the technology, although they show that the use of the technology is feasible. Future work should establish which wearable technology is most valuable to patients, which ones improve patient outcomes, and the most economical model for deploying the technolog

    Adaptive remodeling of the bacterial proteome by specific ribosomal modification regulates Pseudomonas infection and niche colonisation

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    Post-transcriptional control of protein abundance is a highly important, underexplored regulatory process by which organisms respond to their environments. Here we describe an important and previously unidentified regulatory pathway involving the ribosomal modification protein RimK, its regulator proteins RimA and RimB, and the widespread bacterial second messenger cyclic-di-GMP (cdG). Disruption of rimK affects motility and surface attachment in pathogenic and commensal Pseudomonas species, with rimK deletion significantly compromising rhizosphere colonisation by the commensal soil bacterium P. fluorescens, and plant infection by the pathogens P. syringae and P. aeruginosa. RimK functions as an ATP-dependent glutamyl ligase, adding glutamate residues to the C-terminus of ribosomal protein RpsF and inducing specific effects on both ribosome protein complement and function. Deletion of rimK in P. fluorescens leads to markedly reduced levels of multiple ribosomal proteins, and also of the key translational regulator Hfq. In turn, reduced Hfq levels induce specific downstream proteomic changes, with significant increases in multiple ABC transporters, stress response proteins and non-ribosomal peptide synthetases seen for both ΔrimK and Δhfq mutants. The activity of RimK is itself controlled by interactions with RimA, RimB and cdG. We propose that control of RimK activity represents a novel regulatory mechanism that dynamically influences interactions between bacteria and their hosts; translating environmental pressures into dynamic ribosomal changes, and consequently to an adaptive remodeling of the bacterial proteome

    Reaction rates and transport in neutron stars

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    Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions.Comment: 74 pages; commissioned for the book "Physics and Astrophysics of Neutron Stars", NewCompStar COST Action MP1304; version 3: minor changes, references updated, overview graphic added in the introduction, improvements in Sec IV.A.

    Measurement and Interpretation of Fermion-Pair Production at LEP energies above the Z Resonance

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    This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions, for the e+e- -> ffbar process for centre-of-mass energies above the Z resonance, from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to study a variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering and several models which include physics beyond the Standard Model: the exchange of Z' bosons, contact interactions between fermions, the exchange of gravitons in large extra dimensions and the exchange of sneutrino in R-parity violating supersymmetry.Comment: 79 pages, 16 figures, Accepted by Eur. Phys. J.

    A Determination of the Centre-of-Mass Energy at LEP2 using Radiative 2-fermion Events

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    Using e+e- -> mu+mu-(gamma) and e+e- -> qqbar(gamma) events radiative to the Z pole, DELPHI has determined the centre-of-mass energy, sqrt{s}, using energy and momentum constraint methods. The results are expressed as deviations from the nominal LEP centre-of-mass energy, measured using other techniques. The results are found to be compatible with the LEP Energy Working Group estimates for a combination of the 1997 to 2000 data sets.Comment: 20 pages, 6 figures, Accepted by Eur. Phys. J.

    A Measurement of the Tau Hadronic Branching Ratios

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    The exclusive and semi-exclusive branching ratios of the tau lepton hadronic decay modes (h- v_t, h- pi0 v_t, h- pi0 pi0 v_t, h- \geq 2pi0 v_t, h- \geq 3pi0 v_t, 2h- h+ v_t, 2h- h+ pi0 v_t, 2h- h+ \geq 2pi0 v_t, 3h- 2h+ v_t and 3h- 2h+ \geq 1pi0 v_t) were measured with data from the DELPHI detector at LEP.Comment: 53 pages, 18 figures, Accepted by Eur. Phys. J.
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