3,493 research outputs found
One- and two-dimensional higher-point conformal blocks as free-particle wavefunctions in AdS
We establish that all of the one- and two-dimensional global conformal blocks
are, up to some choice of prefactor, free-particle wavefunctions in tensor
products of AdS or limits thereof. Our first core observation is that the
six-point comb-channel conformal blocks correspond to free-particle
wavefunctions on an AdS constructed directly in cross-ratio space. This
construction generalizes to blocks for a special class of diagrams, which are
determined as free-particle wavefunctions in tensor products of AdS.
Conformal blocks for all the remaining topologies are obtained as limits of the
free wavefunctions mentioned above. Our results show directly that the
integrable models associated with all one- and two-dimensional conformal blocks
can be seen as limits of free theory, and manifest a relation between AdS and
CFT kinematics that lies outside of the standard AdS/CFT dictionary. We
complete the discussion by providing explicit Feynman-like rules that can be
used to work out blocks for all topologies, as well as a Mathematica notebook
that allows simple computation of Casimir equations and series expansions for
blocks, by requiring just an OPE diagram as input.Comment: 39 pages + an appendix, 18 figures, Mathematica notebook attache
Feynman Rules for Scalar Conformal Blocks
We complete the proof of "Feynman rules" for constructing -point conformal
blocks with external and internal scalars in any topology for arbitrary in
any spacetime dimension by combining the rules for the blocks (based on their
Witten diagram interpretation) with the rules for the construction of conformal
cross ratios (based on OPE flow diagrams). The full set of Feynman rules leads
to blocks as power series of the hypergeometric type in the conformal cross
ratios. We then provide a proof by recursion of the Feynman rules which relies
heavily on the first Barnes lemma and the decomposition of the topology of
interest in comb-like structures. Finally, we provide a nine-point example to
illustrate the rules.Comment: 61 pages + an appendi
Health-related quality of life among general practice patients with differing chronic diseases in Germany: Cross sectional survey
Background This study was carried out to compare the HRQoL of patients in general practice with differing chronic diseases with the HRQoL of patients without chronic conditions, to evaluate the HRQoL of general practice patients in Germany compared with the HRQoL of the general population, and to explore the influence of different chronic diseases on patients HRQoL, independently of the effects of multiple confounding variables. Methods A cross-sectional questionnaire survey including the SF-36, the EQ-5D and demographic questions was conducted in 20 general practices in Germany. 1009 consecutive patients aged 15–89 participated. The SF-36 scale scores of general practice patients with differing chronic diseases were compared with those of patients without chronic conditions. Differences in the SF-36 scale/summary scores and proportions in the EQ-5D dimensions between patients and the general population were analyzed. Independent effects of chronic conditions and demographic variables on the HRQoL were analyzed using multivariable linear regression and polynomial regression models. Results The HRQoL for general practice patients with differing chronic diseases tended to show more physical than mental health impairments compared with the reference group of patients without. Patients in general practice in Germany had considerably lower SF-36 scores than the general population (P < 0.001 for all) and showed significantly higher proportions of problems in all EQ-5D dimensions except for the self-care dimension (P < 0.001 for all). The mean EQ VAS for general practice patients was lower than that for the general population (69.2 versus 77.4, P < 0.001). The HRQoL for general practice patients in Germany seemed to be more strongly affected by diseases like depression, back pain, OA of the knee, and cancer than by hypertension and diabetes. Conclusion General practice patients with differing chronic diseases in Germany had impaired quality of life, especially in terms of physical health. The independent impacts on the HRQoL were different depending on the type of chronic disease. Findings from this study might help health professionals to concern more influential diseases in primary care from the patient´s perspective
The a-theorem and conformal symmetry breaking in holographic RG flows
We study holographic models describing an RG flow between two fixed points
driven by a relevant scalar operator. We show how to introduce a spurion field
to restore Weyl invariance and compute the anomalous contribution to the
generating functional in even dimensional theories. We find that the
coefficient of the anomalous term is proportional to the difference of the
conformal anomalies of the UV and IR fixed points, as expected from anomaly
matching arguments in field theory. For any even dimensions the coefficient is
positive as implied by the holographic a-theorem. For flows corresponding to
spontaneous breaking of conformal invariance, we also compute the two-point
functions of the energy-momentum tensor and the scalar operator and identify
the dilaton mode. Surprisingly we find that in the simplest models with just
one scalar field there is no dilaton pole in the two-point function of the
scalar operator but a stronger singularity. We discuss the possible
implications.Comment: 50 pages. v2: minor changes, added references, extended discussion.
v3: we have clarified some of the calculations and assumptions, results
unchanged. v4: published version in JHE
Intraocular lenses in age-related macular degeneration
Purpose:
The aim of this work is to review the lenses, assessing their advantages and disadvantages. We describe a total of seven types of intraocular lenses (IOLs) recommended for age-related macular degeneration (AMD).
Methods:
We used the PubMed web platform to search for implantable devices in various stages of AMD. We searched for both prospective and retrospective studies and also case reports.
Results:
Clinical results in AMD patients have been described for a total of seven types of IOLs recommended for AMD: an implantable miniature telescope (IMT), IOL-VIP System, Lipshitz macular implant (LMI), sulcus-implanted Lipshitz macular implant, LMI-SI, Fresnel Prism Intraocular Lens, iolAMD and Scharioth Macula Lens.
Conclusions:
We conclude that to objectively ascertain the effectiveness and safety of these lenses, further independent clinical studies with longer follow-up data are necessary prior to the general use of these optical devices
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