The equation of state of neutron matter, symmetry energy, and neutron star structure

We review the calculation of the equation of state of pure neutron matter using quantum Monte Carlo (QMC) methods. QMC algorithms permit the study of many-body nuclear systems using realistic two- and three-body forces in a nonperturbative framework. We present the results for the equation of state of neutron matter, and focus on the role of three-neutron forces at supranuclear density. We discuss the correlation between the symmetry energy, the neutron star radius and the symmetry energy. We also combine QMC and theoretical models of the three-nucleon interactions, and recent neutron star observations to constrain the value of the symmetry energy and its density dependence.Comment: 11 pages, 11 figure

Uncertainty in the determination of soil hydraulic parameters and its influence on the performance of two hydrological models of different complexity

Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still debated. However, we may wonder how the uncertainty in soil hydraulic parameters relates to the uncertainty of the selected modelling approach. We performed an intensive monitoring study during the cropping season of a 10 ha maize field in Northern Italy. The data were used to: i) compare different methods for determining soil hydraulic parameters and ii) evaluate the effect of the uncertainty in these parameters on different variables (i.e. evapotranspiration, average water content in the root zone, flux at the bottom boundary of the root zone) simulated by two hydrological models of different complexity: SWAP, a widely used model of soil moisture dynamics in unsaturated soils based on Richards equation, and ALHyMUS, a conceptual model of the same dynamics based on a reservoir cascade scheme. We employed five direct and indirect methods to determine soil hydraulic parameters for each horizon of the experimental profile. Two methods were based on a parameter optimization of: a) laboratory measured retention and hydraulic conductivity data and b) field measured retention and hydraulic conductivity data. The remaining three methods were based on the application of widely used Pedo-Transfer Functions: c) Rawls and Brakensiek, d) HYPRES, and e) ROSETTA. Simulations were performed using meteorological, irrigation and crop data measured at the experimental site during the period June – October 2006. Results showed a wide range of soil hydraulic parameter values generated with the different methods, especially for the saturated hydraulic conductivity Ksat and the shape parameter a of the van Genuchten curve. This is reflected in a variability of the modeling results which is, as expected, different for each model and each variable analysed. The variability of the simulated water content in the root zone and of the bottom flux for different soil hydraulic parameter sets is found to be often larger than the difference between modeling results of the two models using the same soil hydraulic parameter set. Also we found that a good agreement in simulated soil moisture patterns may occur even if evapotranspiration and percolation fluxes are significantly different. Therefore multiple output variables should be considered to test the performances of methods and model

Properties of nuclei up to A=16A=16 using local chiral interactions

We report accurate quantum Monte Carlo calculations of nuclei up to $A=16$ based on local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We examine the theoretical uncertainties associated with the chiral expansion and the cutoff in the theory, as well as the associated operator choices in the three-nucleon interactions. While in light nuclei the cutoff variation and systematic uncertainties are rather small, in $^{16}$O these can be significant for large coordinate-space cutoffs. Overall, we show that chiral interactions constructed to reproduce properties of very light systems and nucleon-nucleon scattering give an excellent description of binding energies, charge radii, and form factors for all these nuclei, including open-shell systems in $A=6$ and 12.Comment: 6 pages, 4 figure

Confirmation of an exoplanet using the transit color signature: Kepler-418b, a blended giant planet in a multiplanet system

We announce confirmation of Kepler-418b, one of two proposed planets in this system. This is the first confirmation of an exoplanet based primarily on the transit color signature technique. We used the Kepler public data archive combined with multicolor photometry from the Gran Telescopio de Canarias and radial velocity follow-up using FIES at the Nordic Optical Telescope for confirmation. We report a confident detection of a transit color signature that can only be explained by a compact occulting body, entirely ruling out a contaminating eclipsing binary, a hierarchical triple, or a grazing eclipsing binary. Those findings are corroborated by our radial velocity measurements, which put an upper limit of ~1 Mjup on the mass of Kepler-418b. We also report that the host star is significantly blended, confirming the ~10% light contamination suspected from the crowding metric in the Kepler light curve measured by the Kepler team. We report detection of an unresolved light source that contributes an additional ~40% to the target star, which would not have been detected without multicolor photometric analysis. The resulting planet-star radius ratio is 0.110 +/- 0.0025, more than 25% more than the 0.087 measured by Kepler, leading to a radius of 1.20 +/- 0.16 Rjup instead of the 0.94 Rjup measured by the Kepler team. This is the first confirmation of an exoplanet candidate based primarily on the transit color signature, demonstrating that this technique is viable from ground for giant planets. It is particularly useful for planets with long periods such as Kepler-418b, which tend to have long transit durations. Additionally, multicolor photometric analysis of transits can reveal unknown stellar neighbors and binary companions that do not affect the classification of the transiting object but can have a very significant effect on the perceived planetary radius.Comment: accepted by Astronomy & Astrophysic

The Early Career Framework – A Guide for Mentors and Early Career Teachers

This guide has been developed from findings from the Early Career Teacher Support pilot evaluation (Hardman et al., 2020), funded by the Education Endowment Foundation (EEF). It is one of three guides intended to summarise the key messages from the evaluation and provide strategic and practical suggestions that can inform planning to support the development of Early Career Teachers (ECTs) in schools. The guidance is applicable to all school contexts and is not specific to particular programmes of support. The Early Career Framework (ECF) has been introduced in some parts of England from September 2020 and will be rolled out nationally in September 2021 along with guidance to support participating Early Career Teachers and mentors. Stemming from the Recruitment and Retention Strategy (DfE, 2019) the ECF seeks to ensure that all teachers in England receive high quality support in the first two years of their career. During 2019-20 the Centre for Teachers and Teaching Research at UCL Institute of Education undertook an evaluation of three pilot programmes which were designed to test different ways of supporting Early Career Teachers and their mentors. We worked with the Chartered College of Teaching, Ambition Institute and The Education Endowment Foundation as well as 98 schools (both primary and secondary) to evaluate the impact of these pilot programmes. Following the pilot which we evaluated, the DfE selected four suppliers to develop freely available resources for schools to use. This included a separate team from UCL Institute of Education. We shared our initial findings with these suppliers to inform their materials. From 2021 there will be six suppliers, including UCL Institute of Education, offering programmes based on one of these four initial programmes. Schools now have three options around how they implement the ECF. The guidance in this document is relevant to all three options

The Early Career Framework – A Guide for Implementation

This guide has been developed from findings from the Early Career Teacher Support pilot evaluation (Hardman et al., 2020), funded by the Education Endowment Foundation (EEF). It is one of three guides intended to summarise the key messages from the evaluation and provide strategic and practical suggestions that can inform planning to support the development of Early Career Teachers (ECTs) in schools. The guidance is applicable to all school contexts and is not specific to particular programmes of support. The Early Career Framework (ECF) has been introduced in some parts of England from September 2020 and will be rolled out nationally in September 2021 along with guidance to support participating Early Career Teachers and mentors. Stemming from the Recruitment and Retention Strategy (DfE, 2019) the ECF seeks to ensure that all teachers in England receive high quality support in the first two years of their career. During 2019-20 the Centre for Teachers and Teaching Research at UCL Institute of Education undertook an evaluation of three pilot programmes which were designed to test different ways of supporting Early Career Teachers and their mentors. We worked with the Chartered College of Teaching, Ambition Institute and The Education Endowment Foundation as well as 98 schools (both primary and secondary) to evaluate the impact of these pilot programmes. Following the pilot which we evaluated, the DfE selected four suppliers to develop freely available resources for schools to use. This included a separate team from UCL Institute of Education. We shared our initial findings with these suppliers to inform their materials. From 2021 there will be six suppliers, including UCL Institute of Education, offering programmes based on one of these four initial programmes. Schools now have three options around how they implement the ECF. The guidance in this document is relevant to all three options