Collinear and Soft Limits of Multi-Loop Integrands in N=4 Yang-Mills

It has been argued in arXiv:1112.6432 that the planar four-point integrand in N=4 super Yang-Mills theory is uniquely determined by dual conformal invariance together with the absence of a double pole in the integrand of the logarithm in the limit as a loop integration variable becomes collinear with an external momentum. In this paper we reformulate this condition in a simple way in terms of the amplitude itself, rather than its logarithm, and verify that it holds for two- and three-loop MHV integrands for n>4. We investigate the extent to which this collinear constraint and a constraint on the soft behavior of integrands can be used to determine integrands. We find an interesting complementarity whereby the soft constraint becomes stronger while the collinear constraint becomes weaker at larger n. For certain reasonable choices of basis at two and three loops the two constraints in unison appear strong enough to determine MHV integrands uniquely for all n.Comment: 27 pages, 14 figures; v2: very minor change

All-mass n-gon integrals in n dimensions

We explore the correspondence between one-loop Feynman integrals and (hyperbolic) simplicial geometry to describe the "all-mass" case: integrals with generic external and internal masses. Specifically, we focus on $n$-particle integrals in exactly $n$ space-time dimensions, as these integrals have particularly nice geometric properties and respect a dual conformal symmetry. In four dimensions, we leverage this geometric connection to give a concise dilogarithmic expression for the all-mass box in terms of the Murakami-Yano formula. In five dimensions, we use a generalized Gauss-Bonnet theorem to derive a similar dilogarithmic expression for the all-mass pentagon. We also use the Schl\"afli formula to write down the symbol of these integrals for all $n$. Finally, we discuss how the geometry behind these formulas depends on space-time signature, and we gather together many results related to these integrals from the mathematics and physics literature.Comment: 49 pages, 8 figure

Thermodynamic Bethe Ansatz Equations for Minimal Surfaces in AdS_3

We study classical open string solutions with a null polygonal boundary in AdS_3 in relation to gluon scattering amplitudes in N=4 super Yang-Mills at strong coupling. We derive in full detail the set of integral equations governing the decagonal and the dodecagonal solutions and identify them with the thermodynamic Bethe ansatz equations of the homogeneous sine-Gordon models. By evaluating the free energy in the conformal limit we compute the central charges, from which we observe general correspondence between the polygonal solutions in AdS_n and generalized parafermions.Comment: 25 pages, 4 figures, v2: a figure and references added, minor corrections, v3: references added, minor corrections, to appear in JHE

Atom--Molecule Coherence in a Bose-Einstein Condensate

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

Series Solution and Minimal Surfaces in AdS

According to the Alday-Maldacena program the strong coupling limit of Super Yang-Mills scattering amplitudes is given by minimal area surfaces in AdS spacetime with a boundary consisting of a momentum space polygon. The string equations in AdS systematically reduce to coupled Toda type equations whose Euclidean classical solutions are then of direct relevance. While in the simplest case of AdS_3 exact solutions were known from earlier studies of the sinh-Gordon equation, there exist at present no similar exact forms for the generalized Toda equations related to AdS_d with d>=4. In this paper we develop a series method for the solution to those equations and evaluate their contribution to the finite piece of the worldsheet area. For the known sinh-Gordon case the method is seen to give results in excellent agreement with the exact answer.Comment: 19 pages, no figures; references added, one note adde

Cost-utility model of brivaracetam in the adjunctive treatment of patients with epilepsy in Spain

[EN] Objective This study aims to assess the cost utility of Brivaracetam compared with the third-generation anti-epileptic drugs used as standard care. Methods A cost utility analysis of Brivaracetam was carried out with other third-generation comparators. The treatment pathway of a hypothetical cohort over a period of 2 years was simulated using the Markov model. Data for effectiveness and the QALYs of each health status for epilepsy, as well as for the disutilities of adverse events of treatments, were analyzed through a studies review. The cost of the anti-epileptics and the use of medical resources linked to the different health statuses were taken into consideration. A probabilistic sensitivity analysis was performed using a Monte Carlo simulation. Results Brivaracetam was shown to be the dominant alternative, with Incremental Cost Utility Ratio (ICUR) values from -11,318 for Lacosamide to -128,482 for Zonisamide. The probabilistic sensitivity analysis validates these results. The ICUR sensitivity is greater for increases in the price of Brivaracetam than for decreases, and for Eslicarbizapine over the other adjunctives considered in the analysis. Conclusions Treatment with Brivaracetam resulted in cost effective and incremental quality adjusted life years come at an acceptable cost.Barrachina Martínez, I.; Vivas-Consuelo, D.; Reyes-Santias, F. (2020). Cost-utility model of brivaracetam in the adjunctive treatment of patients with epilepsy in Spain. Expert review of pharmacoeconomics & outcomes research (Online). 1-10. https://doi.org/10.1080/14737167.2021.1838899S110WHO | Epilepsy: aISBN public health imperative. ISBN 978-92-4-151593-1. World Health Organization. 2019. Printed in Thailand.Ngugi, A. K., Kariuki, S. M., Bottomley, C., Kleinschmidt, I., Sander, J. W., & Newton, C. R. (2011). Incidence of epilepsy: A systematic review and meta-analysis. Neurology, 77(10), 1005-1012. doi:10.1212/wnl.0b013e31822cfc90Henning, O., Landmark, C. J., Henning, D., Nakken, K. O., & Lossius, M. I. (2019). Challenges in epilepsy—The perspective of Norwegian epilepsy patients. Acta Neurologica Scandinavica, 140(1), 40-47. doi:10.1111/ane.13098Brodie, M. J. (2005). Diagnosing and predicting refractory epilepsy. Acta Neurologica Scandinavica, 112(s181), 36-39. doi:10.1111/j.1600-0404.2005.00507.xGarcía-Ramos, R., Pastor, A. G., Masjuan, J., Sánchez, C., & Gil, A. (2011). FEEN: Informe sociosantario FEEN sobre la epilepsia en España. Neurología, 26(9), 548-555. doi:10.1016/j.nrl.2011.04.002Kwan, P., & Brodie, M. J. (2000). Early Identification of Refractory Epilepsy. New England Journal of Medicine, 342(5), 314-319. doi:10.1056/nejm200002033420503Brodie, M. J. (2008). Epilepsy: randomised trials and genetic tribulations. The Lancet Neurology, 7(1), 7-8. doi:10.1016/s1474-4422(07)70301-0French, J. A. (2006). Refractory Epilepsy: One Size Does Not Fit All. Epilepsy Currents, 6(6), 177-180. doi:10.1111/j.1535-7511.2006.00137.xLaxer, K. D., Trinka, E., Hirsch, L. J., Cendes, F., Langfitt, J., Delanty, N., … Benbadis, S. R. (2014). The consequences of refractory epilepsy and its treatment. Epilepsy & Behavior, 37, 59-70. doi:10.1016/j.yebeh.2014.05.031Giordano, C., Marchiò, M., Timofeeva, E., & Biagini, G. (2014). Neuroactive Peptides as Putative Mediators of Antiepileptic Ketogenic Diets. Frontiers in Neurology, 5. doi:10.3389/fneur.2014.00063European Medicines Agency. Committee for Medicinal Products for Human Use (CHMP). Briviact brivaracetam. Assessment Report EMA/CHMP/822086/2015 Nov.Markham, A. (2016). Brivaracetam: First Global Approval. Drugs, 76(4), 517-522. doi:10.1007/s40265-016-0555-6Willems, L. M., Bauer, S., Rosenow, F., & Strzelczyk, A. (2019). Recent advances in the pharmacotherapy of epilepsy: brivaracetam and perampanel as broad-spectrum antiseizure drugs for the treatment of epilepsies and status epilepticus. Expert Opinion on Pharmacotherapy, 20(14), 1755-1765. doi:10.1080/14656566.2019.1637420Craig, D., Rice, S., Paton, F., Fox, D., & Woolacott, N. (2013). Retigabine for the Adjunctive Treatment of Adults with Partial-Onset Seizures in Epilepsy with and without Secondary Generalization. PharmacoEconomics, 31(2), 101-110. doi:10.1007/s40273-012-0018-1Charokopou, M., Harvey, R., Srivastava, K., Brandt, C., & Borghs, S. (2019). Relative performance of brivaracetam as adjunctive treatment of focal seizures in adults: a network meta-analysis. Current Medical Research and Opinion, 35(8), 1345-1354. doi:10.1080/03007995.2019.1584501Chhatwal J. Changing cycle lengths in state-transition models: doing it the right way; [cited 2018 Jan 23]. Available from: https://www.ispor.org/News/Connections_methodology_state-transition-models.PDFMulhern, B., Rowen, D., Snape, D., Jacoby, A., Marson, T., Hughes, D., … Brazier, J. (2014). Valuations of epilepsy-specific health states: a comparison of patients with epilepsy and the general population. Epilepsy & Behavior, 36, 12-17. doi:10.1016/j.yebeh.2014.04.011Kristian, B., Wachtmeister, K., Stefan, F., & Forsgren, L. (2013). Retigabine as add-on treatment of refractory epilepsy - a cost-utility study in a Swedish setting. Acta Neurologica Scandinavica, 127(6), 419-426. doi:10.1111/ane.12077Vera-Llonch, M., Brandenburg, N. A., & Oster, G. (2008). Cost-effectiveness of Add-on Therapy with Pregabalin in Patients with Refractory Partial Epilepsy. Epilepsia, 49(3), 431-437. doi:10.1111/j.1528-1167.2007.01279.xSimoens, S. (2010). Pharmacoeconomics of anti-epileptic drugs as adjunctive therapy for refractory epilepsy. Expert Review of Pharmacoeconomics & Outcomes Research, 10(3), 309-315. doi:10.1586/erp.10.18Wijnen, B. F. M., van Mastrigt, G. A. P. G., Evers, S. M. A. A., Gershuni, O., Lambrechts, D. A. J. E., Majoie, M. H. J. M., … de Kinderen, R. J. A. (2017). A systematic review of economic evaluations of treatments for patients with epilepsy. Epilepsia, 58(5), 706-726. doi:10.1111/epi.13655Boeck, J. D., Verpoorten, K., Luyten, K., & Coninx, K. (2007). A Comparison between Decision Trees and Markov Models to Support Proactive Interfaces. 18th International Conference on Database and Expert Systems Applications (DEXA 2007). doi:10.1109/dexa.2007.94Zhang, Y., Wu, H., Denton, B. T., Wilson, J. R., & Lobo, J. M. (2017). Probabilistic sensitivity analysis on Markov models with uncertain transition probabilities: an application in evaluating treatment decisions for type 2 diabetes. Health Care Management Science, 22(1), 34-52. doi:10.1007/s10729-017-9420-8Swallow, E., Fang, A., Signorovitch, J., Plumb, J., & Borghs, S. (2017). Can Matching-Adjusted Indirect Comparison Methods Mitigate Placebo Response Differences Among Patient Populations in Adjunctive Trials of Brivaracetam and Levetiracetam? CNS Drugs, 31(10), 899-910. doi:10.1007/s40263-017-0462-8Malyshkina NV, Mannering FL. Markov switching multinomial logit model: an application to accident injury severities; 2008 [cited 2019 Sep 25]. Available from: http://arxiv.org/abs/0811.3644Hawkins, N., Epstein, D., Drummond, M., Wilby, J., Kainth, A., Chadwick, D., & Sculpher, M. (2005). Assessing the Cost-Effectiveness of New Pharmaceuticals in Epilepsy in Adults: The Results of a Probabilistic Decision Model. Medical Decision Making, 25(5), 493-510. doi:10.1177/0272989x05280559Agencia Española del Medicamento. Utilización de medicamentos antiepilépticos en España durante el periodo 2008–2016 [Internet]; 2017 [cited 2019 Sep 25]. Available from: https://www.aemps.gob.es/medicamentosUsoHumano/observatorio/docs/antiepilepticos-periodo-2008-2016.pdfMegiddo, I., Colson, A., Chisholm, D., Dua, T., Nandi, A., & Laxminarayan, R. (2016). Health and economic benefits of public financing of epilepsy treatment in India: An agent‐based simulation model. Epilepsia, 57(3), 464-474. doi:10.1111/epi.13294De Andrés-Nogales, F., Oyagüez, I., Álvarez-Sala, L. A., García-Bragado, F., Navarro, A., González, P., … Soto, J. (2017). Análisis coste-efectividad y coste-utilidad de apixaban frente a dabigatrán y rivaroxaban en el tratamiento y prevención secundaria del tromboembolismo venoso. PharmacoEconomics Spanish Research Articles, 14(1), 7-18. doi:10.1007/s40277-016-0064-8Fricke-Galindo, I., Jung-Cook, H., LLerena, A., & López-López, M. (2018). Farmacogenética de reacciones adversas a fármacos antiepilépticos. Neurología, 33(3), 165-176. doi:10.1016/j.nrl.2015.03.005Steinhoff, B. J., Bacher, M., Bucurenciu, I., Hillenbrand, B., Intravooth, T., Kornmeier, R., … Staack, A. M. (2017). Real-life experience with brivaracetam in 101 patients with difficult-to-treat epilepsy—A monocenter survey. 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Two Years Later: Journals Are Not Yet Enforcing the ARRIVE Guidelines on Reporting Standards for Pre-Clinical Animal Studies

There is growing concern that poor experimental design and lack of transparent reporting contribute to the frequent failure of pre-clinical animal studies to translate into treatments for human disease. In 2010, the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines were introduced to help improve reporting standards. They were published in PLOS Biology and endorsed by funding agencies and publishers and their journals, including PLOS, Nature research journals, and other top-tier journals. Yet our analysis of papers published in PLOS and Nature journals indicates that there has been very little improvement in reporting standards since then. This suggests that authors, referees, and editors generally are ignoring guidelines, and the editorial endorsement is yet to be effectively implemented

g-Functions and gluon scattering amplitudes at strong coupling

We study gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling by calculating the area of the minimal surfaces in AdS_3 based on the associated thermodynamic Bethe ansatz system. The remainder function of the amplitudes is computed by evaluating the free energy, the T- and Y-functions of the homogeneous sine-Gordon model. Using conformal field theory (CFT) perturbation, we examine the mass corrections to the free energy around the CFT point corresponding to the regular polygonal Wilson loop. Based on the equivalence between the T-functions and the g-functions, which measure the boundary entropy, we calculate corrections to the T- and Y-functions as well as express them at the CFT point by the modular S-matrix. We evaluate the remainder function around the CFT point for 8 and 10-point amplitudes explicitly and compare these analytic expressions with the 2-loop formulas. The two rescaled remainder functions show very similar power series structures.Comment: 51 pages, 4 figures, v2: some comments and references added, based on the published version, v3: minor change

Complete Equivalence Between Gluon Tree Amplitudes in Twistor String Theory and in Gauge Theory

The gluon tree amplitudes of open twistor string theory, defined as contour integrals over the ACCK link variables, are shown to satisfy the BCFW relations, thus confirming that they coincide with the corresponding amplitudes in gauge field theory. In this approach, the integration contours are specified as encircling the zeros of certain constraint functions that force the appropriate relation between the link variables and the twistor string world-sheet variables. To do this, methods for calculating the tree amplitudes using link variables are developed further including diagrammatic methods for organizing and performing the calculations.Comment: 38 page