Parity Doubling and the S Parameter Below the Conformal Window

We describe a lattice simulation of the masses and decay constants of the lowest-lying vector and axial resonances, and the electroweak S parameter, in an SU(3) gauge theory with $N_f = 2$ and 6 fermions in the fundamental representation. The spectrum becomes more parity doubled and the S parameter per electroweak doublet decreases when $N_f$ is increased from 2 to 6, motivating study of these trends as $N_f$ is increased further, toward the critical value for transition from confinement to infrared conformality.Comment: 4 pages, 5 figures; to be submitted to PR

Making space for cultural ecosystem services: insights from a study of the UK Nature Improvement Initiative

A study of the cultural ecosystem services (CES) arising from peoples’ interactions with the rural environment is conducted within the context of a landscape scale, ‘nature improvement’ initiative in the United Kingdom. Taking a mixed methodological approach, the research applies, and demonstrates empirically, a framework for CES developed under the UK National Ecosystem Assessment (Fish et al., 2016). Applications of the framework involve the study of the ‘environmental spaces’ and ‘cultural practices’ that contribute to the realisation of benefits to well-being. In this paper empirical work is undertaken to inform the CES evidence base informing management priorities of the Northern Devon Nature Improvement Area (NDNIA) in south west England. Findings from a questionnaire survey, qualitative mapping, group discussion and a participatory arts-based research process are presented to document the many and diverse ways this study area matters to local communities. The paper analyses the qualities that research participants attribute to the environmental space of the NDNIA, the cultural practices conducted and enabled within it, and their associated benefits. The implications of the study for applying this framework through mixed methodological research are discussed, alongside an account of the impact of this approach within the NDNIA itself.This research was funded through the UK National Ecosystem Assessment Follow-On (Work Package 5: Cultural ecosystem services and indicators) funded by the UK Department of the Environment, Food and Rural Affairs (Defra), the Welsh Government, the UK Natural Environment Research Council (NERC), Economic and Social Research Council (ESRC), and Arts and Humanities Research Council (AHRC)

ARPES: A probe of electronic correlations

Angle-resolved photoemission spectroscopy (ARPES) is one of the most direct methods of studying the electronic structure of solids. By measuring the kinetic energy and angular distribution of the electrons photoemitted from a sample illuminated with sufficiently high-energy radiation, one can gain information on both the energy and momentum of the electrons propagating inside a material. This is of vital importance in elucidating the connection between electronic, magnetic, and chemical structure of solids, in particular for those complex systems which cannot be appropriately described within the independent-particle picture. Among the various classes of complex systems, of great interest are the transition metal oxides, which have been at the center stage in condensed matter physics for the last four decades. Following a general introduction to the topic, we will lay the theoretical basis needed to understand the pivotal role of ARPES in the study of such systems. After a brief overview on the state-of-the-art capabilities of the technique, we will review some of the most interesting and relevant case studies of the novel physics revealed by ARPES in 3d-, 4d- and 5d-based oxides.Comment: Chapter to appear in "Strongly Correlated Systems: Experimental Techniques", edited by A. Avella and F. Mancini, Springer Series in Solid-State Sciences (2013). A high-resolution version can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Reviews/ARPES_Springer.pdf. arXiv admin note: text overlap with arXiv:cond-mat/0307085, arXiv:cond-mat/020850

Measurement of Peroxide Values in Oils by Triphenylphosphine/Triphenylphosphine Oxide (TPP/TPPO) Assay Coupled with FTIR-ATR Spectroscopy: Comparison with Iodometric Titration

Hydroperoxides (LOOH) measurement is a common technique to determine the degree of oxidation of oils and fats. Although it appears to have some limitations (time consuming, and uses of toxic solvents as chloroform), the iodometric titration is one of the most common methods. Herein, an alternative method by measuring the oxidation level using Fourier transform infrared (FTIR) with an attenuated total reflectance mode (ATR), based on the stoichiometric conversion of triphenylphosphine (TPP) into triphenylphosphine oxide (TPPO) by hydroperoxides, is proposed. The FTIR-ATR spectroscopy allows for a simple and accurate detection of the TPPO formed by selective reaction with LOOH, with measurement of its specific adsorption band at 542cm(-1). Calibration is made with TPPO solubilized in butan-2-one and covers a range of peroxide values (PV) from approximate to 2 to approximate to 800mEqkg(-1). The comparison of the iodometric titration and TPP/TPPO assay is performed with standard hydroperoxides (tert-butyl hydroperoxide and cumene hydroperoxide). The iodometric titration shows higher PV overestimations in comparison with the TPP/TPPO assay, for both hydroperoxides. An accelerated oxidation of different oils is assessed with the two methods, and the results confirm this observation since higher PV values are measured with the titration method. The TPP/TPPO assay coupled with the ATR-FTIR spectroscopy appears as a simpler and faster assay, which may limit overestimation and use of toxic solvents, especially suitable for routine analysis of oil and fats.Practical Applications: One of the first indicator of oxidation in oils and fats is the presence of hydroperoxides, therefore, it is important to find a reliable method to assess these oxidation products. One of the most common methods to determine lipid hydroperoxide (LOOH) concentrations is iodometric titration. Although this method is simple to set up, it is labor-intensive, time consuming, and uses a lot of solvent. TPP/TPPO assay coupled with FTIR-ATR spectroscopy is a good alternative to the iodometric method since it allows a fast and robust hydroperoxide measurement, with minimal use of organic solvents. This rapid peroxide value determination can be adapted for routine quality control analyses, especially for oxidation in real-time and accelerated aging assays to evaluate oxidative stability during shelf-life, for industrial purpose or lab scale experiments. The TPP/TPPO coupled with FTIR-ATR allows for a fast, simple, reasonably sensitive (adequate for most purposes) and reproducible alternative assay to conventional iodometric titration for peroxide value assessment