853 research outputs found

    Exact two-particle eigenstates in partially reduced QED

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    We consider a reformulation of QED in which covariant Green functions are used to solve for the electromagnetic field in terms of the fermion fields. It is shown that exact few-fermion eigenstates of the resulting Hamiltonian can be obtained in the canonical equal-time formalism for the case where there are no free photons. These eigenstates lead to two- and three-body Dirac-like equations with electromagnetic interactions. Perturbative and some numerical solutions of the two-body equations are presented for positronium and muonium-like systems, for various strengths of the coupling.Comment: 33 pages, LaTex 2.09, 4 figures in EPS forma

    On the formation history of Galactic double neutron stars

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    Double neutron stars (DNSs) have been observed as Galactic radio pulsars, and the recent discovery of gravitational waves from the DN merger GW170817 adds to the known DNS population. We perform rapi population synthesis of massive binary stars and discuss mode predictions, including DNS formation rates, mass distributions, an delay time distributions. We vary assumptions and parameters of physica processes such as mass transfer stability criteria, supernova natal kic distributions, remnant mass prescriptions, and common-envelop eccentricity distribution of the Galactic DNS population under each o our population synthesis models, allowing us to quantitatively compar burning secondary (case BB) on to a neutron star is most likel dynamically stable. We also find that a natal kick distribution compose of both low (Maxwellian σ =30 km s^{-1}) and high (σ =265 km s^{-1} components is preferred over a single high-kick component. We conclud that the observed DNS mass distribution can place strong constraints o model assumption

    Production of entanglement in Raman three-level systems using feedback

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    We examine the theoretical limits of the generation of entanglement in a damped coupled ion-cavity system using jump-based feedback. Using Raman transitions to produce entanglement between ground states reduces the necessary feedback bandwidth, but does not improve the overall effect of the spontaneous emission on the final entanglement. We find that the fidelity of the resulting entanglement will be limited by the asymmetries produced by vibrations in the trap, but that the concurrence remains above 0.88 for realistic ion trap sizes.Comment: 8 pages, 8 figure

    Certolizumab Pegol for Treating Rheumatoid Arthritis Following Inadequate Response to a TNF-α Inhibitor: An Evidence Review Group Perspective of a NICE Single Technology Appraisal.

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    As part of its single technology appraisal (STA) process, the National Institute for Health and Care Excellence (NICE) invited the manufacturer (UCB Pharma) of certolizumab pegol (CZP; Cimzia(®)) to submit evidence of its clinical and cost effectiveness for the treatment of rheumatoid arthritis (RA) following inadequate response to a tumour necrosis factor-α inhibitor (TNFi). The School of Health and Related Research Technology Appraisal Group at the University of Sheffield was commissioned to act as the independent Evidence Review Group (ERG). The ERG produced a detailed review of the evidence for the clinical and cost effectiveness of the technology, based upon the company's submission to NICE. The clinical effectiveness evidence in the company's submission for CZP was based predominantly on six randomised controlled trials (RCTs) comparing the efficacy of CZP against placebo. The clinical effectiveness review identified no head-to-head evidence on the efficacy of CZP against the comparators within the scope; therefore, the company performed a network meta-analysis (NMA). The company's NMA concluded that CZP had a similar efficacy to that of its comparators. The company submitted a Markov model that assessed the incremental cost effectiveness of CZP versus comparator biologic disease-modifying antirheumatic drugs (bDMARDs) for the treatment of RA from the perspective of the National Health Service for three decision problems, each of which followed an inadequate response to a TNFi. These were (1) a comparison against rituximab (RTX) in combination with methotrexate (MTX); (2) a comparison against bDMARDs when RTX was contraindicated or withdrawn due to an adverse event; and (3) a comparison against bDMARDs when MTX was contraindicated or withdrawn due to an adverse event. Results from the company's economic evaluation showed that CZP resulted in a similar number of quality-adjusted life years (QALYs) produced at similar or lower costs compared with comparator bDMARDs. The commercial-in-confidence patient access schemes for abatacept and tocilizumab could not be incorporated by the company, but were incorporated by the ERG in a confidential appendix for the NICE Appraisal Committee (AC). The company estimated that the addition of CZP before RTX in a sequence for patients who could receive MTX produced more QALYs at an increased cost, with a cost per QALY of £33,222. Following a critique of the model, the ERG undertook exploratory analyses that did not change the conclusions reached based on the company's economic evaluation in relation to the comparison with bDMARDs. The ERG estimated that where CZP replaced RTX, CZP was dominated, as it produced fewer QALYs at an increased cost. The AC concluded that there was little difference in effectiveness between CZP and comparator bDMARDs and that equivalence among bDMARDs could be accepted. The AC consequently recommended CZP plus MTX for people for whom RTX is contraindicated or not tolerated and CZP monotherapy for people for whom MTX is contraindicated or not tolerated. The AC concluded that CZP plus MTX could not be considered a cost-effective use of National Health Service resources when RTX plus MTX is a treatment option

    Perturbation Theory with a Variational Basis: the Generalized Gaussian Effective Potential

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    The perturbation theory with a variational basis is constructed and analyzed.The generalized Gaussian effective potential is introduced and evaluated up to the second order for selfinteracting scalar fields in one and two spatial dimensions. The problem of the renormalization of the mass is discussed in details. Thermal corrections are incorporated. The comparison between the finite temperature generalized Gaussian effective potential and the finite temperature effective potential is critically analyzed. The phenomenon of the restoration at high temperature of the symmetry broken at zero temperature is discussed.Comment: RevTex, 49 pages, 16 eps figure

    Certolizumab Pegol for Treating Rheumatoid Arthritis Following Inadequate Response to a TNF-α Inhibitor: An Evidence Review Group Perspective of a NICE Single Technology Appraisal.

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    As part of its single technology appraisal (STA) process, the National Institute for Health and Care Excellence (NICE) invited the manufacturer (UCB Pharma) of certolizumab pegol (CZP; Cimzia(®)) to submit evidence of its clinical and cost effectiveness for the treatment of rheumatoid arthritis (RA) following inadequate response to a tumour necrosis factor-α inhibitor (TNFi). The School of Health and Related Research Technology Appraisal Group at the University of Sheffield was commissioned to act as the independent Evidence Review Group (ERG). The ERG produced a detailed review of the evidence for the clinical and cost effectiveness of the technology, based upon the company's submission to NICE. The clinical effectiveness evidence in the company's submission for CZP was based predominantly on six randomised controlled trials (RCTs) comparing the efficacy of CZP against placebo. The clinical effectiveness review identified no head-to-head evidence on the efficacy of CZP against the comparators within the scope; therefore, the company performed a network meta-analysis (NMA). The company's NMA concluded that CZP had a similar efficacy to that of its comparators. The company submitted a Markov model that assessed the incremental cost effectiveness of CZP versus comparator biologic disease-modifying antirheumatic drugs (bDMARDs) for the treatment of RA from the perspective of the National Health Service for three decision problems, each of which followed an inadequate response to a TNFi. These were (1) a comparison against rituximab (RTX) in combination with methotrexate (MTX); (2) a comparison against bDMARDs when RTX was contraindicated or withdrawn due to an adverse event; and (3) a comparison against bDMARDs when MTX was contraindicated or withdrawn due to an adverse event. Results from the company's economic evaluation showed that CZP resulted in a similar number of quality-adjusted life years (QALYs) produced at similar or lower costs compared with comparator bDMARDs. The commercial-in-confidence patient access schemes for abatacept and tocilizumab could not be incorporated by the company, but were incorporated by the ERG in a confidential appendix for the NICE Appraisal Committee (AC). The company estimated that the addition of CZP before RTX in a sequence for patients who could receive MTX produced more QALYs at an increased cost, with a cost per QALY of £33,222. Following a critique of the model, the ERG undertook exploratory analyses that did not change the conclusions reached based on the company's economic evaluation in relation to the comparison with bDMARDs. The ERG estimated that where CZP replaced RTX, CZP was dominated, as it produced fewer QALYs at an increased cost. The AC concluded that there was little difference in effectiveness between CZP and comparator bDMARDs and that equivalence among bDMARDs could be accepted. The AC consequently recommended CZP plus MTX for people for whom RTX is contraindicated or not tolerated and CZP monotherapy for people for whom MTX is contraindicated or not tolerated. The AC concluded that CZP plus MTX could not be considered a cost-effective use of National Health Service resources when RTX plus MTX is a treatment option
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