EFFECTS OF COVER BOARD AGE, SEASON, AND HABITAT ON THE OBSERVED ABUNDANCE OF EASTERN RED-BACKED SALAMANDERS (PLETHODON CINEREUS)

Plethodontid salamanders are potentially good ecological indicator species in woodland habitats due to their abundance and sensitivity to changes in the environment. The use of terrestrial salamanders as ecological indicators depends on effective means of surveying their abundance and distribution. Our study examined the use of old and new artificial cover boards by Eastern Red-backed Salamanders (Plethodon cinereus). We also considered the effects of season (spring vs. fall) and habitat type (deciduous vs. coniferous vs. mixed) on cover board use by P. cinereus. Our results indicated that P. cinereus abundance was greater under old cover boards compared to new cover boards. However, the difference between the use of old and new cover boards was greater during the spring than the fall, suggesting that the effect of cover board age became weaker over time. Plethodon cinereus showed strong seasonal variation in observed abundance, with peaks during the spring and fall seasons and very low surface activity during the summer. Plethodon cinereus had higher observed abundance in deciduous habitats than in coniferous and mixed habitats. Our results suggested that care should be taken to account for cover board age in long-term monitoring programs, especially if cover boards are replaced during a study

Approaches to Three-Dimensional Transformation Optical Media Using Quasi-Conformal Coordinate Transformations

We introduce an approach to the design of three-dimensional transformation optical (TO) media based on a generalized quasi-conformal mapping approach. The generalized quasi-conformal TO (QCTO) approach enables the design of media that can, in principle, be broadband and low-loss, while controlling the propagation of waves with arbitrary angles of incidence and polarization. We illustrate the method in the design of a three-dimensional "carpet" ground plane cloak and of a flattened Luneburg lens. Ray-trace studies provide a confirmation of the performance of the QCTO media, while also revealing the limited performance of index-only versions of these devices

Asset Pricing with Observable Stochastic Discount Factors.

The stochastic discount factor model provides a general framework for pricing assets. By specifying the discount factor suitably it encompasses most of the theories currently in use, including CAPM and consumption CAPM. The SDF model has been based on the use of single and multiple factors, and on latent and observed factors. In most situations, and especially for the term structure, single factor models are inappropriate, whilst latent variables require the somewhat arbitrary specification of generating processes and are difficult to interpret. In this paper we survey the principal different implementations of the SDF model for FOREX, equity and bonds and we propose a new approach. This is based on the use of multiple factors that are observable and modelling the joint distribution of excess returns and the factors using a multi-variate GARCH-in-mean process. We argue that in general single equation and VAR models, although widely used in empirical finance, are inappropriate as they do not satisfy the no-arbitrage condition. Since risk premia arise from conditional covariation between returns and the factors, both a multi-variate context and having conditional covariances in the conditional mean process, is essential. We explain how apparent exceptions, such as the CIR and Vasicek models, in fact meet this requirement - but at a price. We explain our new approach, discuss how it might be implemented and present some empirical evidence, mainly from our own researches. Partly, to enable comparisons to be made, the survey also includes evidence from recent empirical work using more traditional approaches.Asset Pricing; Stochastic Discount Factors; Forex; Equity Term Structure; Affine Factor Models; Consumption CAPM; Financial Econometrics; GARCH

Parameter estimation applied to Nimbus 6 wide-angle longwave radiation measurements

A parameter estimation technique was used to analyze the August 1975 Nimbus 6 Earth radiation budget data to demonstrate the concept of deconvolution. The longwave radiation field at the top of the atmosphere is defined from satellite data by a fifth degree and fifth order spherical harmonic representation. The variations of the major features of the radiation field are defined by analyzing the data separately for each two-day duty cycle. A table of coefficient values for each spherical harmonic representation is given along with global mean, gradients, degree variances, and contour plots. In addition, the entire data set is analyzed to define the monthly average radiation field

Trends in long-term prescribing of dependence forming medicines

Using patient-level primary care data to estimate the extent to which antidepressant medicines are prescribed to people continuously for long periods of time. Aim This descriptive research used patient-level primary care data to estimate the extent to which antidepressant medicines are prescribed to people continuously for long periods of time. The study also drew on survey data and data on the number of prescriptions dispensed. Findings - The number of antidepressant prescriptions dispensed each year in England doubled between 2008 and 2018 - Survey data show that the proportion of adults reporting use of antidepressants in the past year increased in the 1990s, and again between 2007 and 2014 - The average length of time that antidepressants are continuously prescribed to people for has increased over time. - Some types of antidepressants (for example, tricyclics and other antidepressants) tend to be prescribed for longer periods than other types (such as SSRIs). - In 2014, one in twelve prescribing periods for tricyclics and other antidepressants lasted for three years or more Methods The analyses in this report are descriptive and show the overall prevalence of long-term prescribing in each year. We used a sample of around 50,000 patients prescribed at least one antidepressant medicine between 2000 and 2017. This was drawn from the Clinical Practice Research Datalink (CPRD). The CPRD contains data about prescriptions issued by GPs (including the length and size of prescription) and characteristics of the patients prescribed to (such as their age, sex, and area where they live). Medicines were grouped for analysis into: tricyclics, selective serotonin reuptake inhibitors (SSRIs), and other ADMs. The length of individual prescriptions and continuous prescribing periods were derived using information on consultation dates, the quantity of tablets prescribed, and the numeric daily dose

Light echoes reveal an unexpectedly cool Eta Carinae during its 19th-century Great Eruption

Eta Carinae (Eta Car) is one of the most massive binary stars in the Milky Way. It became the second-brightest star in the sky during its mid-19th century "Great Eruption," but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique among known astronomical transients in that it exceeded the Eddington luminosity limit for 10 years. Because it is only 2.3 kpc away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that in its 19th century eruption, Eta Car ejected more than 10 M_solar in an event that had 10% of the energy of a typical core-collapse supernova without destroying the star. Here we report the discovery of light echoes of Eta Carinae which appear to be from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km/s, in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-G5 supergiant spectra, which have effective temperatures of ~5000 K. In contrast to the class of extragalactic outbursts assumed to be analogs of Eta Car's Great Eruption, the effective temperature of its outburst is significantly cooler than allowed by standard opaque wind models. This indicates that other physical mechanisms like an energetic blast wave may have triggered and influenced the eruption.Comment: Accepted for publication by Nature; 4 pages, 4 figures, SI: 6 pages, 3 figures, 5 table

Macroeconmic Sources of FOREX Risk.

This paper considers the problem of measuring macroeconomic sources of financial risk. 1. It aims to provide a general theory of asset pricing suitable for taking account of macroeconomic sources of risk. Stochastic discount factor theory is used to provide the theoretical framework. This is capable of embracing most of the approaches in the literature, including general equilibrium theory. Market structure needs to be added to this. 2. It is shown that many of the models used in the empirical literature of asset pricing have a fundamental flaw: they admit unlimited arbitrage opportunities. High profile suites of computer programs just produced and sold world-wide suffer the same problem, and hence should not be used. 3. Modelling the exchange rate is key to much of monetary policy (eg the Bank of England's Monetary Policy Committee), and to testing FOREX market efficiency. The forward premium puzzle lies at the heart of the difficulty of doing this. The theoretical results of this paper are used to re-examine the distribution of exchange rate movements and to try to resolve this puzzle. Stochastic discount factor theory is used to derive expressions for the risk premia for domestic and foreign investors. It is shown that these are likely to be different. A combined theory of market risk when both types of investor are trading is then obtained. The cases of complete and incomplete markets are considered. It is shown how macroeconomic sources of risk can be introduced by modelling the stochastic discount factor using observable macroeconomic variables. Three SDF models are compared: a benchmark model which provides a reformulation of traditional tests of FOREX efficiency; inter-temporal consumption-based CAPM; and the monetary model of the exchange rate, a familiar macroeconomic model of FOREX which can be interpreted as arising from traditional hedging concerns. The joint distribution of the excess return to foreign exchange and the macro factors is specified in a way that satisfies the no-arbitrage assumption. It is assumed that the joint distribution has multivariate GARCH and it is shown that to eliminate arbitrage opportunities it is necessary for the conditional distribution of the excess return to exhibit GARCH-in-mean. The omission of the conditional covariance between the excess return and the sources of risk is the reason why nearly all financial statistical packages are not suitable for use in financial econometrics. The presence of this term implies that the analysis must be conducted in a multi-variate and not a uni-variate framework. The theory admits the possibility that domestic and foreign investors may have different attitudes to risk. This is incorporated into the model by introducing a switching formulation of the conditional covariance structure. Extreme changes in exchange rates suggest that the usual assumption of log-normality may fail to capture the excess kurtosis of excess returns. The model is therefore also estimated assuming a log t-distribution. It is notoriously difficult to achieve convergence in multi-variate GARCH models, and GARCH-in-mean effects increase the difficulty. This is a major limitation in the practicality of the whole approach. It is shown that assuming constant correlation greatly simplifies the estimation without sacrificing any essential elements. Tests are conducted to enable a comparison of different SDF models, different market structures, different attitudes to risk, and differences between the SDF model and the Fama approach. The empirical work is based on monthly data for the sterling-dollar exchange rate 1975-1997. Our main new finding is that the evidence is more consistent with the FOREX risk premium arising from traditional partial equilibrium models of currency risk that form the basis of hedging than with consumption-CAPM, a general equilibrium theory. In particular, US and UK output appear to be important sources of FOREX risk.FOREX, market efficiency, risk premium, stochastic discount factors, GARCH.