TBA-like equations and Casimir effect in (non-)perturbative AdS/CFT

We consider high spin, $s$, long twist, $L$, planar operators (asymptotic Bethe Ansatz) of strong ${\cal N}=4$ SYM. Precisely, we compute the minimal anomalous dimensions for large 't Hooft coupling $\lambda$ to the lowest order of the (string) scaling variable $\ell \sim L/ (\ln \mathcal{S} \sqrt{\lambda})$ with GKP string size $\sim\ln \mathcal{S}\equiv 2 \ln (s/\sqrt{\lambda})$. At the leading order $(\ln \mathcal{S}) \cdot \ell ^2$, we can confirm the O(6) non-linear sigma model description for this bulk term, without boundary term $(\ln \mathcal{S})^0$. Going further, we derive, extending the O(6) regime, the exact effect of the size finiteness. In particular, we compute, at all loops, the first Casimir correction $\ell ^0/\ln \mathcal{S}$ (in terms of the infinite size O(6) NLSM), which reveals only one massless mode (out of five), as predictable once the O(6) description has been extended. Consequently, upon comparing with string theory expansion, at one loop our findings agree for large twist, while reveal for negligible twist, already at this order, the appearance of wrapping. At two loops, as well as for next loops and orders, we can produce predictions, which may guide future string computations.Comment: Version 2 with: new exact expression for the Casimir energy derived (beyond the first two loops of the previous version); UV theory formulated and analysed extensively in the Appendix C; origin of the O(6) NLSM scattering clarified; typos correct and references adde

Event-based quickflow simulation with OpenLISEM in a burned Mediterranean forest catchment

Recently burnt areas typically reveal strong to extreme hydrological responses, as a consequence of loss of protective soil cover and heating-induced changes in topsoil properties. Soil water repellency (SWR) has frequently been referred to as one of the explanatory variables for fireenhanced surface runoff generation but this has been poorly demonstrated, especially at the catchment scale. This study employs a process-based modelling approach to better understand the relevance of SWR in the hydrological response of a small, entirely burnt catchment in central Portugal, in particular by comparing hydrological events under contrasting initial conditions of dry vs wet soils. The OpenLISEM model was applied to a selection of 16 major rainfall runoff events that occurred during the first 2 post-fire years. The automatic calibration procedure resulted in good model performance, but it worsened for validation events. Furthermore, uncertainty analysis revealed an elevated sensitivity of OpenLISEM to event-specific conditions, especially for predicting the events’ total and peak flows. Also, predicted spatial patterns in runoff poorly agreed with the runoff observed in microplots. Model performance improved when events were separated by dry and wet initial moisture conditions, particularly for wet conditions, suggesting the role of variables other than initial soil moisture.info:eu-repo/semantics/publishedVersio

Multi-Regge kinematics and the moduli space of Riemann spheres with marked points

We show that scattering amplitudes in planar N = 4 Super Yang-Mills in multi-Regge kinematics can naturally be expressed in terms of single-valued iterated integrals on the moduli space of Riemann spheres with marked points. As a consequence, scattering amplitudes in this limit can be expressed as convolutions that can easily be computed using Stokes' theorem. We apply this framework to MHV amplitudes to leading-logarithmic accuracy (LLA), and we prove that at L loops all MHV amplitudes are determined by amplitudes with up to L + 4 external legs. We also investigate non-MHV amplitudes, and we show that they can be obtained by convoluting the MHV results with a certain helicity flip kernel. We classify all leading singularities that appear at LLA in the Regge limit for arbitrary helicity configurations and any number of external legs. Finally, we use our new framework to obtain explicit analytic results at LLA for all MHV amplitudes up to five loops and all non-MHV amplitudes with up to eight external legs and four loops.Comment: 104 pages, six awesome figures and ancillary files containing the results in Mathematica forma

Sensorimotor synchronization when walking side by side with a point light walker

[Excerpt] Synchronization of periodic movements like side-by-side walking [7] is frequently modeled by coupled oscillators [5] and the coupling strength is defined quantitatively [3]. In contrast, in most studies on sensorimotor synchronization (SMS), simple movements like finger taps are synchronized with simple stimuli like metronomes [4]. While the latter paradigm simplifies matters and allows for the assessment of the relative weights of sensory modalities through systematic variation of the stimuli [1], it might lack ecological validity. Conversely, using more complex movements and stimuli might complicate the specification of mechanisms underlying coupling. We merged the positive aspects of both approaches to study the contribution of auditory and visual information on synchronization during side-by-side walking. As stimuli, we used Point Light Walkers (PLWs) and auralized steps sound; both were constructed from previously captured walking individuals [2][6]. PLWs were retro-projected on a screen and matched according to gender, hip height, and velocity. The participant walked for 7.20m side by side with 1) a PLW, 2) steps sound, or 3) both displayed in temporal congruence. Instruction to participants was to synchronize with the available stimuli. [...]Acknowledgments: [Supported by Fundação Bial (Grant 77/12) and Fundação para a Ciência e Tecnologia - FCT: SFRH/BD/88396/2012; EXPL/MHC-PCN/0162/2013; FCOMP-01-0124 - FEDER-022674 and PEst-C/CTM/U10264/2011; FCOMP-01-0124-FEDER-037281 and PEstC/EEI/LA0014/2013. This work was financed by FEDER grants through the Operational Competitiveness Program – COMPETE]

Modern rhodolith-dominated carbonates at Punta Chivato, Mexico

Rhodolith-dominated carbonate environments, characterized by high abundances of free-living coralline algae, have been described globally from a wide range of Recent and fossil shallow marine settings. In the present-day warm-temperate Gulf of California, Mexico, rhodolith-dominated systems are important contributors to carbonate production. One of the most prolific rhodolith factories is located on the Punta Chivato shelf, in the central Gulf of California, where due to a lack of input of terrigenous material from the arid hinterland, carbonate content averages 79%. Punta Chivato rhodoliths thrive above the shallow euphotic zone under normal saline, warm-temperate and meso- to eutrophic conditions. A detailed sedimentologic study combined with acoustic seafloor mapping indicates the presence of extensive rhodolith-dominated facies at subtidal water depth covering an area of \u3e17 km2. Additional facies, surrounding the rhodolith-dominated facies include a fine-grained molluscan, a transitional bivalve-rhodolith and a bivalve facies. While the Punta Chivato shelf yields average abundances of 38% rhodolith-derived coralline algal components in the gravel-sized sediment fraction, the rhodolith facies itself is characterized by more than 60% coralline algal components. Other important carbonate producers at Punta Chivato include bivalves (35%), bryozoa (11%) and gastropods (8%). The present study shows that acoustic sediment mapping yields highly resolved continuous coverage of the seafloor and can distinguish modern rhodolith facies from surrounding sediment. This has important implications for quantifying rhodolith-dominated settings globally, as well as for ecological and conservation studies. © Publications Scientifiques du Muséum national d\u27Histoire naturelle, Paris

Functional Integration Approach to Hysteresis

A general formulation of scalar hysteresis is proposed. This formulation is based on two steps. First, a generating function g(x) is associated with an individual system, and a hysteresis evolution operator is defined by an appropriate envelope construction applied to g(x), inspired by the overdamped dynamics of systems evolving in multistable free energy landscapes. Second, the average hysteresis response of an ensemble of such systems is expressed as a functional integral over the space G of all admissible generating functions, under the assumption that an appropriate measure m has been introduced in G. The consequences of the formulation are analyzed in detail in the case where the measure m is generated by a continuous, Markovian stochastic process. The calculation of the hysteresis properties of the ensemble is reduced to the solution of the level-crossing problem for the stochastic process. In particular, it is shown that, when the process is translationally invariant (homogeneous), the ensuing hysteresis properties can be exactly described by the Preisach model of hysteresis, and the associated Preisach distribution is expressed in closed analytic form in terms of the drift and diffusion parameters of the Markovian process. Possible applications of the formulation are suggested, concerning the interpretation of magnetic hysteresis due to domain wall motion in quenched-in disorder, and the interpretation of critical state models of superconducting hysteresis.Comment: 36 pages, 9 figures, to be published on Phys. Rev.

The mirror module design for the cryogenic x-ray imaging spectrometer on-board ORIGIN

ORIGIN is a medium size high-energy mission concept submitted to ESA in response to the Cosmic Vision call issued on July 2010. The mission will investigate the evolution of the Universe by performing soft X-ray high resolution spectroscopic measurements of metals formed in different astrophysical environments, from the first population III stars at z > 7 to the present large scale structures. The main instrument on-board ORIGIN will be a large format array of TES X-ray micro-calorimeters covering a FOV of 30' at the focal plane of a grazing incidence optical module with a focal length of 2.5 m and an angular resolution of 30'' HEW at 1 keV. We present the optical module design which is based on hybrid technologies, namely Silicon Pore Optics for the outer section and Ni electro-forming for the inner section, and we present the expected performances based on test measurements and ray-tracing simulations

Developing and testing a robotic MRI/CT fusion biopsy technique using a purpose-built interventional phantom.

BACKGROUND: Magnetic resonance imaging (MRI) can be used to target tumour components in biopsy procedures, while the ability to precisely correlate histology and MRI signal is crucial for imaging biomarker validation. Robotic MRI/computed tomography (CT) fusion biopsy offers the potential for this without in-gantry biopsy, although requires development. METHODS: Test-retest T1 and T2 relaxation times, attenuation (Hounsfield units, HU), and biopsy core quality were prospectively assessed (January-December 2021) in a range of gelatin, agar, and mixed gelatin/agar solutions of differing concentrations on days 1 and 8 after manufacture. Suitable materials were chosen, and four biopsy phantoms were constructed with twelve spherical 1-3-cm diameter targets visible on MRI, but not on CT. A technical pipeline was developed, and intraoperator and interoperator reliability was tested in four operators performing a total of 96 biopsies. Statistical analysis included T1, T2, and HU repeatability using Bland-Altman analysis, Dice similarity coefficient (DSC), and intraoperator and interoperator reliability. RESULTS: T1, T2, and HU repeatability had 95% limits-of-agreement of 8.3%, 3.4%, and 17.9%, respectively. The phantom was highly reproducible, with DSC of 0.93 versus 0.92 for scanning the same or two different phantoms, respectively. Hit rate was 100% (96/96 targets), and all operators performed robotic biopsies using a single volumetric acquisition. The fastest procedure time was 32 min for all 12 targets. CONCLUSIONS: A reproducible biopsy phantom was developed, validated, and used to test robotic MRI/CT-fusion biopsy. The technique was highly accurate, reliable, and achievable in clinically acceptable timescales meaning it is suitable for clinical application