Analogue Methods in Palaeoecology: Using the analogue Package

Palaeoecology is an important branch of ecology that uses the subfossil remains of organisms preserved in lake, ocean and bog sediments to inform on changes in ecosystems and the environment through time. The analogue package contains functions to perform modern analogue technique (MAT) transfer functions, which can be used to predict past changes in the environment, such as climate or lake-water pH from species data. A related technique is that of analogue matching, which is concerned with identifying modern sites that are floristically and faunistically similar to fossil samples. These techniques, and others, are increasingly being used to inform public policy on environmental pollution and conservation practices. These methods and other functionality in analogue are illustrated using the Surface Waters Acidification Project diatom:pH training set and diatom counts on samples of a sediment core from the Round Loch of Glenhead, Galloway, Scotland. The paper is aimed at palaeoecologists who are familiar with the techniques described but not with R.

Effects of Aspen Phenolic Glycosides on Gypsy Moth (Lepidoptera: Lymantriidae) Susceptibility to \u3ci\u3eBacillus Thuringiensis\u3c/i\u3e

Performance of the gypsy moth, Lymantria dispar, on quaking aspen, Populus tremuloides, is strongly affected by foliar concentrations of phenolic glycosides. Because the microbial insecticide Bacillus thuringiensis is widely used against gypsy moths and has a mode of action similar to that of phenolic glycosIdes, we investigated the combined effects of the two toxins on gypsy moth larvae. The experimental design was a 2 x 2 factorial: two levels (0, +) of phenolicglycosides for each of two levels (0, +) of B. thuringiensis. The toxins were incorporated into artificial diets and bioassayed against first and fourth instars. Bacillus thuringiensis and phenolic glycosides ne~atively and addi· tively affected larval survival, growth and development tImes. Both agents slightly reduced consumption rates. In addition, B. thuringiensis reduced diet digestibility whereas phenolic glycosides decreased the efficiency with which food was converted to biomass. These results suggest that the efficacy of B. thuringiensis applications in aspen forests is likely to be affected by the allelo· chemical composition of foliage

Unemployment insurance claims and economic activity

Economic forecasters pay especially close attention to labor market indicators during periods of economic uncertainty. Labor market data are thought to provide early evidence about changes in the course of the economy. This article examines whether monthly changes in labor market indicators are useful for predicting real GDP. It then examines whether weekly changes in initial and continuing unemployment insurance claims are useful for helping to predict changes in important labor market indicators. Incoming monthly data on nonfarm payroll jobs and the index of aggregate weekly hours help predict changes in real GDP growth, but data on the civilian unemployment rate do not. The authors also find that unemployment insurance claims help to predict changes in monthly labor variables. As others have found, these predictions work best in periods of recession. However, this article shows that there was also some predictive ability during the 1990s expansion.Unemployment ; Labor market

Stability in a model of staggered-reserve accounting

An investigation of the nature of the dynamic process implied by staggered-reserve accounting, using a simple reduced-form model of the money-supply process.Bank reserves ; Money supply

Forecasting inflation and output: comparing data-rich models with simple rules

There has been a resurgence of interest in dynamic factor models for use by policy advisors. Dynamic factor methods can be used to incorporate a wide range of economic information when forecasting or measuring economic shocks. This article introduces dynamic factor models that underlie the data-rich methods and also tests whether the data-rich models can help a benchmark autoregressive model forecast alternative measures of inflation and real economic activity at horizons of 3, 12, and 24 months ahead. The authors find that, over the past decade, the data-rich models significantly improve the forecasts for a variety of real output and inflation indicators. For all the series that they examine, the authors find that the data-rich models become more useful when forecasting over longer horizons. The exception is the unemployment rate, where the principal components provide significant forecasting information at all horizons.Inflation (Finance) ; Economic forecasting

Available labor supply

Labor supply ; Employment

Velocity: a multivariate time-series approach

The Federal Reserve announces targets for the monetary aggregates that are implicitly conditioned on an assumption about future velocity for each of the monetary aggregates. In this paper we present explicit models of velocity for constructing rigorous tests to determine whether the behavior of velocity has changed from what was expected when the targets were chosen. We use time-series methods to develop alternative forecasts of velocity. Multivariate time-series models of velocity that include information about past interest rates produce significantly better out-of-sample forecasts than do univariate methods. Using this multivariate time-series framework, we analyze the Federal Reserve's decisions to change, miss, and switch targets from 1980:IQ to l984:IIQ. For this period, we find that when the Federal Reserve deviated from its announced target, velocity deviated significantly from its predicted value.Money supply ; Time-series analysis

Catalytic constructive deoxygenation of lignin-derived phenols: new C-C bond formation processes from imidazole-sulfonates and ether cleavage reactions

Funding: UK Engineering and Physical Sciences Research Council (EPSRC)As part of a programme aimed at exploiting lignin as a chemical feedstock for less oxygenated fine chemicals, several catalytic C-C bond forming reactions utilising guaiacol imidazole sulfonate are demonstrated. These include the cross-coupling of a Grignard, a non-toxic cyanide source, a benzoxazole, and nitromethane. A modified Meyers reaction is used to accomplish a second constructive deoxygenation on a benzoxazole functionalised anisole.Publisher PDFPeer reviewe

Exploring the formation by core accretion and the luminosity evolution of directly imaged planets: The case of HIP 65426 b

A low-mass companion to the two-solar mass star HIP65426 has recently been detected by SPHERE at around 100 au from its host. Explaining the presence of super-Jovian planets at large separations, as revealed by direct imaging, is currently an open question. We want to derive statistical constraints on the mass and initial entropy of HIP65426b and to explore possible formation pathways of directly imaged objects within the core-accretion paradigm, focusing on HIP65426b. Constraints on the planet's mass and post-formation entropy are derived from its age and luminosity combined with cooling models. For the first time, the results of population synthesis are also used to inform the results. Then, a formation model that includes N-body dynamics with several embryos per disc is used to study possible formation histories and the properties of possible additional companions. Finally, the outcomes of two- and three-planet scattering in the post-disc phase are analysed, taking tides into account. The mass of HIP65426b is found to be Mp = 9.9 +1.1 -1.8 MJ using the hot population and Mp = 10.9 +1.4 -2.0 MJ with the cold-nominal population. Core formation at small separations from the star followed by outward scattering and runaway accretion at a few hundred AU succeeds in reproducing the mass and separation of HIP65426b. Alternatively, systems having two or more giant planets close enough to be on an unstable orbit at disc dispersal are likely to end up with one planet on a wide HIP65426b-like orbit with a relatively high eccentricity (>~ 0.5). If this scattering scenario explains its formation, HIP65426b is predicted to have a high eccentricity and to be accompanied by one or several roughly Jovian-mass planets at smaller semi-major axes, which also could have a high eccentricity. This could be tested by further direct-imaging as well as radial-velocity observations.Comment: 17 pages, 11 figures. A&A in press. Bern EXoplanet cooling curves (BEX) available upon request. v2: Language and other minor changes; Fig. 4 now has labels summarising a possible formation pathway discussed in the tex

Quantum magnetism in the rare-earth pyrosilicates

2021 Spring.Includes bibliographical references.In recent years, both physicists and non-physicists have shown immense interest in the burgeoning field of quantum computing and the possible applications a quantum computer could be used for [1]. However, current quantum computers suffer from issues of decoherence: where the quantum state used for computation is broken by external noise. A new possible avenue for quantum computation would be to use systems that are intrinsically protected from some level of noise, such as topologically protected states. Topological states are inherently protected from small perturbations due to their topological nature. However, to exploit this feature of topologically protected systems more experimental realizations are needed to better understand the underlying mechanisms. This has motivated a surge in interest of condensed matter systems with topologically protected states, such as the quantum spin liquid or fractional quantum Hall systems. A current focus in the subfield of quantum magnetism has focused on using the anisotropic exchange properties of the rare-earth (La - Lu) ions to find quantum spin liquid states, such as the Kitaev spin liquid that is predicted for systems exhibiting a honeycomb lattice. The Kitaev model is an exactly solvable model with a quantum spin liquid ground state, allowing for precise comparison between experiment and theory. Currently, no system has been rigorously proven to be a Kitaev spin liquid but developing our understanding of the underlying physical mechanisms in these systems may allow for the "engineering" of systems that are likely to be Kitaev spin liquids. The desire to understand the underlying mechanisms for quantum spin liquids and other quantum ground states led to the study of the three-honeycomb rare-earth pyrosilicate compounds discussed in this dissertation. The first compound, Yb2Si2O7, is a quantum dimer magnet system with the first evidence for a rare-earth based triplon Bose-Einstein condensate. Inelastic neutronscattering, specific heat, and ultrasound velocity measurements showed a characteristic (for triplon Bose-Einstein condensates) dome in the field-temperature phase diagram and provided evidence for predominantly isotropic exchange, something that is not typically expected for rare-earth systems. Following this work on Yb2Si2O7, our focused turned to two of the Er3+ rare-earth pyrosilicates. The first of these Er3+-based pyrosilicates measured was D-Er2Si2O7. Previous work on D-Er2Si2O7 discovered a highly anisotropic g-tensor, an antiferromagnetic ground state, and modeled some of the magnetic field induced transitions via Monte-Carlo simulations [2]. Our work followed up on this with AC susceptibility, powder inelastic neutron scattering, and powder neutron diffraction measurements to further investigate the ground state of this quantum magnet. Through this we discovered that the system enters an antiferromagnetic state with the spins almost aligned along the previously determined local Ising-axis [2]. The inelastic neutron scattering spectrum show a gapped excitation at zero field - consistent with Ising-like exchange. Transverse field AC susceptibility shows a change in the susceptibility at 2.65 T. These signatures indicate that D-Er2Si2O7 exhibits predominantly Ising-like exchange and that a transition can be induced by a field applied transverse to the Ising axis. This allows for the possibility of D-Er2Si2O7 bein g a new experimental realization of the Transverse Field Ising Model (TFIM). The TFIM is a simple, anisotropic exchange, theoretically tractable model exhibiting quantum criticality with few experimental examples, making new experimental examples of this model highly desired. These intriguing results on D-Er2Si2O7 and Yb2Si2O7 led to an interest in the polymorph formed at lower synthesis temperatures, C-Er2Si2O7, which happens to be isostructural to Yb2Si2O7. Measurements of the neutron diffraction, specific heat, and magnetization/susceptibility in this system allowed for us to determine that C-Er2Si2O7 magnetically orders at 2.3 K into an antiferromagnetic Néel state. While this is the expected ground state for an isotropically exchange coupled honeycomb system, C-Er2Si2O7 does not form a "perfect" honeycomb lattice and it is interesting that C-Er2Si2O7 magnetically orders while Yb2Si2O7 does not. Understanding the ground state for C-Er2Si2O7 will allow for bettering our understanding of Yb2Si2O7 and rare-earth quantum magnet ground states by comparing the properties of the two systems. Overall, the work on these three compounds required numerous experimental techniques, models, and theoretical understanding. It is my hope that the preliminary understanding for these three pyrosilicates will motivate future work within the rare-earth pyrosilicate family and provide a family of rare-earth quantum magnets that can be studied to improve our understanding of novel quantum states