Young and Intermediate-age Distance Indicators

Distance measurements beyond geometrical and semi-geometrical methods, rely mainly on standard candles. As the name suggests, these objects have known luminosities by virtue of their intrinsic proprieties and play a major role in our understanding of modern cosmology. The main caveats associated with standard candles are their absolute calibration, contamination of the sample from other sources and systematic uncertainties. The absolute calibration mainly depends on their chemical composition and age. To understand the impact of these effects on the distance scale, it is essential to develop methods based on different sample of standard candles. Here we review the fundamental properties of young and intermediate-age distance indicators such as Cepheids, Mira variables and Red Clump stars and the recent developments in their application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in Space Science Reviews (Chapter 3 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

Customer emotions in service failure and recovery encounters

Emotions play a significant role in the workplace, and considerable attention has been given to the study of employee emotions. Customers also play a central function in organizations, but much less is known about customer emotions. This chapter reviews the growing literature on customer emotions in employee–customer interfaces with a focus on service failure and recovery encounters, where emotions are heightened. It highlights emerging themes and key findings, addresses the measurement, modeling, and management of customer emotions, and identifies future research streams. Attention is given to emotional contagion, relationships between affective and cognitive processes, customer anger, customer rage, and individual differences

Global data set of long-term summertime vertical temperature profiles in 153 lakes

peer reviewedClimate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of lake thermal structure in a time of rapid global and ecological change. © 2021, The Author(s)

Alkenones are common in prairie lakes of interior Canada

Long chain alkenone (LCA) lipids produced by haptophyte algae are ubiquitous in marine environments and are increasingly reported from enhanced conductivity, solute rich lakes worldwide. Following our survey of lakes in the United States (Toney et al., 10.1016/j.gca.2009.11.021), we examined surface sediments from 19 lakes in central Canada for alkenones and compared our data with lake characteristics. We found that 68% of surveyed lakes contained sedimentary LCAs, all have C37:4me dominated profiles. Lakes containing LCAs had salinities >1.5 g/l and SO4/CO3 ratios >3.5. LCA concentrations were highly elevated (∑C37 > 500 μg/g sediment) in sediments of meromictic lakes with permanently anoxic deep waters. Overall, the distribution of LCAs was consistent with a previous survey of lakes in the interior of the United States demonstrating that tetra-unsaturated lipids were most common in sulfate rich, saline lakes. Alkenone unsaturation indices (View the MathML source) from the upper 10 cm of the sediment column are weakly correlated with point sampled average spring water temperature (r2 = 0.30, p = 0.067) and the range of inferred temperatures is in agreement with the average, long term potential evapotranspiration weighted temperature

Environmental factors influencing the pigment composition of in situ benthic microbial communities in east Antarctic lakes

To compile reference data for palaeolimnological studies using fossil pigments, we examined the extent to which environmental variables, gross morphology and species composition influence the modern pigment content of in situ microbial communities in 62 east Antarctic lakes. Pigment contents, measured using HPLC, were compared with 32 environmental variables, gross microbial mat morphology and cyanobacterial species composition in each lake. Results showed low concentrations or an absence of pigments in the water columns of most lakes. For benthic microbial communities, multivariate statistical analyses identified lake depth as the most important factor explaining pigment composition. In deeper lakes the pigment composition was dominated by chlorophylls, in intermediate depth lakes by chlorophylls and carotenoids, and in shallow lakes by scytonemins, ultraviolet-screening pigments found in cyanobacteria. In addition to lake depth, conductivity, turbidity, dissolved oxygen, sulphate and geographical location were all significant (p less than or equal to 0.05) in explaining variance in the pigment content. Significant differences in microbial mat gross morphologies occurred at different lake depths (p less than or equal to 0.01), and were characterised by significant differences in their pigment content (p less than or equal to 0.004). Despite the high abundance of scytonemin in shallow lakes, there were only limited changes in the absolute concentrations of chlorophylls and carotenoids. We conclude that lake depth is the most significant factor influencing both gross mat morphology and pigment content, presumably as a result of its influence on the light climate. In general, the ability of the cyanobacteria to regulate their pigment content, morphology, community composition and motility to best exploit the light environment at different lake depths may explain their dominance in these systems

Consequences of fish kills for long-term trophic structure in shallow lakes: Implications for theory and restoration

Fish kills are a common occurrence in shallow, eutrophic lakes, but their ecological consequences, especially in the long-term, are poorly understood. We studied the decadal-scale response of two UK shallow lakes to fish kills using a palaeolimnological approach. Eutrophic and turbid Barningham Lake experienced two fish kills in the early 1950s and late 1970s with fish recovering after both events, whereas less eutrophic, macrophyte-dominated Wolterton Lake experienced one kill event in the early 1970s from which fish failed to recover. Our palaeo-data show fish-driven trophic cascade effects across all trophic levels (covering benthic and pelagic species) in both lakes regardless of pre-kill macrophyte coverage and trophic status. In turbid Barningham Lake, similar to long-term studies of biomanipulations in other eutrophic lakes, effects at the macrophyte-level are shown to be temporary after the first kill (c. 20 years) and non-existent after the second kill. In plant-dominated Wolterton Lake permanent fish disappearance failed to halt a long-term pattern of macrophyte community change (e.g. loss of charophytes and over-wintering macrophyte species) symptomatic of eutrophication. Important implications for theory and restoration ecology arise from our study. Firstly, our data support ideas of slow eutrophication-driven change in shallow lakes where perturbations are not necessary prerequisites for macrophyte loss. Secondly, the study emphasises a key need for lake managers to reduce external nutrient-loading if sustainable and long-term lake restoration is to be achieved. Our research highlights the enormous potential of multi-indicator palaeolimnology and alludes to an important need to consider potential fish kill signatures when interpreting results