Two-dimensional Ising model with Einstein site phonons

This work was supported by CONICET (Argentina), and ANPCYT (Argentina) via Grant PICT-2013-2004.We consider a simple Ising magnetic model in two dimensions with Einstein site phonons and study it using Monte Carlo simulations that take into account both degrees of freedom simultaneously. In nonfrustrated systems, like the square lattice with ferromagnetic and antiferromagnetic interactions, we find that the coupling of the magnetic to the elastic degrees of freedom gradually lowers the magnetic ordering transition until it is completely suppressed at a critical value of the coupling constant. Above this the system suffers a simultaneous magnetic and structural transition into a dimerized state with lower crystalline symmetry and ferromagnetic clusters antiferromagnetically aligned. In the case of the Kagomé lattice with antiferromagnetic interactions, which is frustrated, we show that a similar ordered state takes place when the coupling constant is above a critical value.PostprintPeer reviewe

Anomalous out-of-equilibrium dynamics in the spin-ice material Dy2Ti2O7 under moderate magnetic fields

This work was supported by Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) through grants PICT 2013-2004, PICT 2014-2618 and PICT 2017-2347, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) through Grant PIP 0446.We study experimentally and numerically the dynamics of the spin ice material Dy2Ti2O7 in the low temperature (T) and moderate magnetic field (B) regime (T ∈ [0.1, 1.7]  K, B ∈ [0, 0.3]  T). Our objective is to understand the main physics shaping the out-of-equilibrium magnetisation vs temperature curves in two different regimes. Very far from equilibrium, turning on the magnetic field after having cooled the system in zero field (ZFC) can increase the concentration of magnetic monopoles (localised thermal excitations present in these systems); this accelerates the dynamics. Similarly to electrolytes, this occurs through dissociation of bound monopole pairs. However, for spin ices the polarisation of the vacuum out of which the monopole pairs are created is a key factor shaping the magnetisation curves, with no analog. We observe a threshold field near 0.2 T for this fast dynamics to take place, linked to the maximum magnetic force between the attracting pairs. Surprisingly, within a regime of low temperatures and moderate fields, an extended Ohm's law can be used to describe the ZFC magnetisation curve obtained with the dipolar spin-ice model. However, in real samples the acceleration of the dynamics appears even sharper than in simulations, possibly due to the presence of avalanches. On the other hand, the effect of the field nearer equilibrium can be just the opposite to that at very low temperatures. Single crystals, as noted before for powders, abandon equilibrium at a blocking temperature TB which increases with field. Curiously, this behaviour is present in numerical simulations even within the nearest-neighbours interactions model. Simulations and experiments show that the increasing trend in TB is stronger for B||[100]. This suggests that the field plays a part in the dynamical arrest through monopole suppression, which is quite manifest for this field orientation.PostprintPeer reviewe

ECOG-ACRIN (E4805) Randomized Phase II Study to Determine the Effect of 2 Different Doses of Aflibercept in Patients with Metastatic Renal Cell Carcinoma

Background—Aflibercept is a recombinantly-produced fusion protein that has potent anti-VEGF activity. We tested whether aflibercept has clinical activity in clear cell renal cell carcinoma (ccRCC). The recommended Phase 2 dose was 4 mg/kg but several patients treated at 1 mg/kg demonstrated prolonged progression-free survival (PFS). We therefore tested both doses in a parallel group randomized trial. Methods—Eligible patients (pts) had histologically confirmed advanced or metastatic ccRCC and previous treatments including prior exposure to a VEGF RTKI. Patients received aflibercept (either 1 mg/kg or 4 mg/kg) day 1 of a 14-day cycle until progression. Patients randomized to 1 mg/kg could crossover to 4 mg/kg at progression. The primary endpoint was proportion alive and progression-free at 8 weeks. A Simon 2-stage design was used for each arm with 33 and 24 eligible pts/arm enrolled in stages 1 and 2. Results—94 pts were enrolled, 59 and 35 to 4 mg and 1 mg doses, respectively. 72% had 1 prior tx most commonly sunitinib. 16 eligible pts crossed over at progression to the 4 mg dose. Most common adverse events were hypertension, proteinuria, and fatigue. Only 4 pts reported Grade 4 or higher toxicity. With 36/59 (61%) pts PFS at 8 wks, the 4-mg/kg dose met protocol specified efficacy criteria. Conclusions—Aflibercept is active in previously treated ccRCC and may be worthy of further study

Study of solar brightness profiles in the 18-26 GHz frequency range with INAF radio telescopes I: solar radius

The Sun is an extraordinary workbench, from which several fundamental astronomical parameters can be measured with high precision. Among these parameters, the solar radius $R_{\odot}$ plays an important role in several aspects, such as in evolutionary models. Despite the efforts in obtaining accurate measurements of $R_{\odot}$, the subject is still debated and measurements are puzzling and/or lacking in many frequency ranges. We aimed to determine the mean, equatorial, and polar radii of the Sun ($R_c$, $R_{eq}$, and $R_{pol}$) in the frequency range 18.1 - 26.1 GHz. We employed single-dish observations from the newly-appointed Medicina "Gavril Grueff" Radio Telescope and the Sardinia Radio Telescope (SRT) throughout 5 years, from 2018 to mid-2023, in the framework of the SunDish project for solar monitoring. Two methods to calculate the radius at radio frequencies are considered and compared. To assess the quality of our radius determinations, we also analysed the possible degrading effects of the antenna beam pattern on our solar maps, using two 2D-models. We carried out a correlation analysis with the evolution of the solar cycle through the calculation of Pearson's correlation coefficient $\rho$. We obtained several values for the solar radius - ranging between 959 and 994 arcsec - and $\rho$, with typical errors of a few arcsec. Our $R_{\odot}$ measurements, consistent with values reported in literature, suggest a weak prolatness of the solar limb ($R_{eq}$ > $R_{pol}$), although $R_{eq}$ and $R_{pol}$ are statistically compatible within 3$\sigma$ errors. The correlation analysis using the solar images from Grueff shows (1) a positive correlation between the solar activity and the temporal variation of $R_c$ (and $R_{eq}$) at all observing frequencies, and (2) a weak anti-correlation between the temporal variation of $R_{pol}$ and the solar activity at 25.8 GHz.Comment: 18 pages, 12 figures, 6 tables, accepted by A&A; v

Gravitational waves from single neutron stars: an advanced detector era survey

With the doors beginning to swing open on the new gravitational wave astronomy, this review provides an up-to-date survey of the most important physical mechanisms that could lead to emission of potentially detectable gravitational radiation from isolated and accreting neutron stars. In particular we discuss the gravitational wave-driven instability and asteroseismology formalism of the f- and r-modes, the different ways that a neutron star could form and sustain a non-axisymmetric quadrupolar "mountain" deformation, the excitation of oscillations during magnetar flares and the possible gravitational wave signature of pulsar glitches. We focus on progress made in the recent years in each topic, make a fresh assessment of the gravitational wave detectability of each mechanism and, finally, highlight key problems and desiderata for future work.Comment: 39 pages, 12 figures, 2 tables. Chapter of the book "Physics and Astrophysics of Neutron Stars", NewCompStar COST Action 1304. Minor corrections to match published versio

Observation of an Excited Bc+ State

Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date

Multi-wavelength observations of the lensed quasar PKS 1830−-211 during the 2019 γ\gamma-ray flare

PKS 1830$-$211 is a $\gamma$-ray emitting, high-redshift (z $= 2.507 \pm 0.002$), lensed flat-spectrum radio quasar. During the period mid-February to mid-April 2019, this source underwent a series of strong $\gamma$-ray flares that were detected by both AGILE-GRID and Fermi-LAT, reaching a maximum $\gamma$-ray flux of $F_{\rm E>100 MeV}\approx 2.3\times10^{-5}$ ph cm$^{-2}$ s$^{-1}$. Here we report on a coordinated campaign from both on-ground (Medicina, OVRO, REM, SRT) and orbiting facilities (AGILE, Fermi, INTEGRAL, NuSTAR, Swift, Chandra), with the aim of investigating the multi-wavelength properties of PKS 1830$-$211 through nearly simultaneous observations presented here for the first time. We find a possible break in the radio spectra in different epochs above 15 GHz, and a clear maximum of the 15 GHz data approximately 110 days after the $\gamma$-ray main activity periods. The spectral energy distribution shows a very pronounced Compton dominance (> 200) which challenges the canonical one-component emission model. Therefore we propose that the cooled electrons of the first component are re-accelerated to a second component by, e.g., kink or tearing instability during the $\gamma$-ray flaring periods. We also note that PKS 1830$-$211 could be a promising candidate for future observations with both Compton satellites (e.g., e-ASTROGAM) and Cherenkov arrays (CTAO) which will help, thanks to their improved sensitivity, in extending the data availability in energy bands currently uncovered.Comment: Accepted for publication in MNRAS. 16 pages, 18 figures, 12 table

Clinical Effectiveness of Transversus Abdominis Plane (TAP) Block versus Local Anesthesia Wound Infiltration for Postoperative Pain Relief After Laparoscopic Appendicectomy in Children: A Study Protocol for a Multicenter Double-Blind Randomized Controlled Phase III Trial

Geoffrey Bloy,1 Amelie Jurine,1 Yann Chaussy,2 Frederic Auber,2 Pierre-Gregoire Guinot,3 Belaid Bouhemad,3 Michel Francois,4 Lucie Vettoretti,1 Sebastien Pili-Floury,5 Maxime Nguyen,3 Guillaume Besch5 1CHU Besançon, Département d’Anesthésie Réanimation Chirurgicale, Besançon, F-25000, France; 2Université de Franche-Comté, CHU Besançon, SINERGIES, Service de Chirurgie Pédiatrique, Besançon, F-25000, France; 3University of Burgundy and Franche-Comté, Dijon University Hospital, INSERM LNC UMR1231, FCS Bourgogne Franche-Comté LipSTIC LabEx, Dijon, F-21000, France; 4Université de Bourgogne, CHU Dijon, Service de Chirurgie Pédiatrique, Dijon, F-21000, France; 5Université de Franche-Comté, CHU Besançon, SINERGIES, Département d’Anesthésie Réanimation Chirurgicale, Besançon, F-25000, FranceCorrespondence: Guillaume Besch, Département d’Anesthésie Réanimation Chirurgicale, CHU Besançon, 3 bvd Alexandre Fleming, Besançon, 25030, France, Tel +3381218958, Fax +3381669331, Email [email protected]: Postoperative pain relief after laparoscopic appendicectomy is a key determinant of early rehabilitation in children. Recent guidelines recommend performing either a transversus abdominis plane (TAP) block or local anesthesia (LA) wound infiltration as part of multimodal postoperative analgesia after appendectomy. To date, the clinical effectiveness of TAP block versus LA wound infiltration has never been compared. The hypothesis of this study is that the TAP block may provide a greater opioid-sparing effect after laparoscopic appendicectomy in children than LA wound infiltration.Study Design and Methods: We designed a multicenter double-blind randomized controlled phase III trial and aim to include 110 children who undergo laparoscopic appendicectomy. Children are randomized to receive either TAP block (TAP group) or LA wound infiltration (infiltration group). Multimodal analgesia is standardized in the two groups using the same protocol, which includes the stepwise prescription of paracetamol, phloroglucinol, ketoprofene, and nalbuphine according to the hetero-evaluation of pain performed by the nurses who were blinded to the treatment allocated using the validated FLACC scale. The primary outcome is the total dose of nalbuphine administered within 24 hours after surgery.Discussion: No study has specifically compared the clinical effectiveness of TAP block versus LA wound infiltration for postoperative pain relief after laparoscopic appendectomy in children. This paper describes the protocol for a randomized trial that addresses this issue. The results of this trial will be useful for editing guidelines with a higher level of evidence on this topic.Keywords: laparoscopic appendectomy, TAP block, wound infiltration, analgesia, childre