1,670 research outputs found
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
-particle integrals in exactly 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 . 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. Seizure, 48, 11-14. doi:10.1016/j.seizure.2017.03.010De Kinderen, R. J. A., Wijnen, B. F. M., van Breukelen, G., Postulart, D., Majoie, M. H. J. 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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
TSG-6 protects cartilage and bone by modulating the activities of chondrocytes and osteoclasts: a potential therapeutic for musculoskeletal disorders
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