Characterization of Water Quality and Phytoplankton Dynamics in the Cooling Pond of the Ottertail Power Plant, Milbank, SD

Ottertail Power Plant maintains a 350-acre artificial pond to provide cooling water to the boilers within their plant. Over the past several years, plant managers have witnessed frequent blooms of noxious algae, fish kills, fish stunting and odor problems within the pond and calcium carbonate build-up on structures within the plant. The objective of this project was to develop baseline data describing current physical, chemical and biological conditions within the cooling pond. Characteristics measured were water temperature, dissolved oxygen, specific conductance, total hardness, nitrate and ammonia nitrogen, total phosphorus, water transparency, chlorophyll a and total and relative abundance of phytoplankton. Water temperatures varied seasonally by site and temperatures were highest and most variable near the plant effluent structure. Total hardness (mean = 1699, range = 1250 to 2070 mg/L as CaCO3) and specific conductance (mean = 4315, range = 3151 to 5847 uS/cm) also varied seasonally and both were highest near the effluent structure. Total phosphorus concentrations (mean = 0.93, range = 0.32 to 2.16 mg/L) were two to five times higher than measured ammonia (mean = 0.44, range = 0.13 to 3.48 mg/L as N) and nitrate (mean = 0.31, range = 0.10 to 2.6) nitrogen combined. Chlorophyll a (mean = 33.7, range = 0 to 352.4 ug/L) and Secchi depth (mean = 64.7, range = 25 to 120 cm) were found to be highest during the winter months. Total phytoplankton cell counts averaged 31,088 cells/ml and ranged from 13,392 to 66,423 cells/ml. Diatoms, green algae and euglenophytes were found in greater abundance during the winter months (mean = 11,043, range = 0 to 43,101 cells/ml) while cyanobacteria predominated during the warmer summer months (mean = 11,030, range = 0 to 28,709 cells/ml) at all sites. Calcium carbonate precipitation appears to be a function of high primary production and high calcium concentrations during the months of December to February. High nutrient concentrations and low nitrogen to phosphorus ratios appear to favor cyanobacteria during the summer months. Results of this effort provide a baseline against which future changes can be measured within the cooling pond. Data collected from this effort will be used to guide cooling pond managemen

Water Quality of Phytoplankton Dynamics of the Ottertail Poer Plant Cooling Pond, Milbank, SD

Ottertail Power Company maintains a 350-acre cooling pond to provide water to the boilers in their plant. Over the past several years, plant managers have witnessed blooms of algae, fish kills and calcium carbonate build-up on structures in the plant. The objectives of this project were to (1) develop baseline data describing current physical, chemical and biological conditions within the pond (2) develop a long-term monitoring plan for the pond and (3) draft recommendations to facilitate improvement of conditions within the pond. Water temperature, dissolved oxygen, conductivity, total hardness, total nitrogen, total phosphorus, water transparency, chlorophyll a and total and relative abundance of phytoplankton were measured monthly from five locations and three depths during 1998 and 1999. Ratio of total nitrogen (range 2.55 to 5.31 mg/L) to total phosphorus (range = 0.32 to 4.40 mg/L) averaged 3:1. Water temperatures varied by site and date (range 3 to 45ºC). Dissolved oxygen ranged from 0.2 to 15.0 mg/L. Total phytoplankton counts ranged from 11,776 to 66,423 cells/ml. Chrysophyta, Chlorophyta and Euglenophyta were found in greater abundance during the winter months (range = 0 to 43,101 cells/ml) while Cyanobacteria dominated during the summer months (range = 0 to 28,709 cells/ml) at all sites. Calcium carbonate precipitation appears to be a function of high primary production and high calcium concentrations. Low nitrogen to phosphorus ratios appears to favor summer blooms of Cyanobacteria. Summer fish kills appear to coincide with high summer water temperatures and low oxygen levels. Water temperatures during a fish kill in July 1998 approached 40ºC while oxygen levels from mid-depth to the bottom were less than 4.0 mg/L. Results of this effort provide a baseline against which future changes can be measured in the pond. Monitoring protocols have been established to facilitate future monitoring of the pond and corrective management prescriptions are under development

Nutrient Loadings and Phytoplankton Dymanics Within a Power Plant Cooling Pond

Cultural eutrophication within the Ottertail Power Plant cooling pond has led to frequent blooms of noxious algae, fish kills, and odor problems. The objectives of this project were to (1) estimate phosphorus and nitrogen loadings to the cooling pond and (2) evaluate seasonal phytoplankton dynamics and pond trophic state. Water chemistries and phytoplankton samples were collected monthly over the period January 1 to December 31, 1998 and 1999. Total nitrogen, total phosphorus, and phytoplankton counts were analyzed according to standard limnological methods. Sources of nutrient loading include Big Stone Lake water, fly ash pond return flows, domestic wastewater and overwintering waterfowl. Big Stone Lake water was found to contribute the greatest nitrogen load (4.8 g m-2 yr-1) while waterfowl were estimated to contribute the greatest total phosphorus load (0.54 g m-2 yr-1). An average volume of 3,532,766 m3/yr is pumped from Big Stone Lake into the Ottertail Cooling pond and contributes on average 76% of total nitrogen and 39% of total phosphorus loads. Overwintering waterfowl (average number = 13,464) contribute 27% of total nitrogen and 91% of total phosphorus load, respectively. Nitrogen: phosphorus ratios (by mass) average 3.2:1 in the cooling pond versus 15.7:1 in Big Stone Lake. Total phytoplankton cell counts averaged 39,099 cells/ml and ranged from 11,776 to 66,423 cells/ml. Diatoms, green algae and euglenophytes were found in great abundance during winter months (range = 0 to 30,248 cells/ml) while cyanobacteria predominated during the warmer summer months (range = 0 to 28,709 cells/ml) at all sites. High nutrient concentrations and low nitrogen to phosphorus ratios suggest that nitrogen may be limiting to algal productivity relative to phosphorus, favoring Cyanobacteria capable of fixing nitrogen during summer months

High-resolution spectroscopy of a young, low-metallicity optically-thin L=0.02L* star-forming galaxy at z=3.12

We present VLT/X-Shooter and MUSE spectroscopy of an faint F814W=28.60+/-0.33 (Muv=-17.0), low mass (~<10^7 Msun) and compact (Reff=62pc) freshly star-forming galaxy at z=3.1169 magnified (16x) by the Hubble Frontier Fields galaxy cluster Abell S1063. Gravitational lensing allows for a significant jump toward low-luminosity regimes, in moderately high resolution spectroscopy (R=lambda/dlambda ~ 3000-7400). We measured CIV1548,1550, HeII1640, OIII]1661,1666, CIII]1907,1909, Hbeta, [OIII]4959,5007, emission lines with FWHM< 50 km/s and (de-lensed) fluxes spanning the interval 1.0x10^-19 - 2.0x10^-18 erg/s/cm2 at S/N=4-30. The double peaked Lya emission with Delta_v(red-blue) = 280(+/-7)km/s and de-lensed fluxes 2.4_(blue)|8.5_(red)x10^-18 erg/s/cm2 (S/N=38_(blue)|110_(red)) indicate a low column density of neutral hydrogen gas consistent with a highly ionized interstellar medium as also inferred from the large [OIII]5007/[OII]3727>10 ratio. We detect CIV1548,1550 resonant doublet in emission, each component with FWHM ~< 45 km/s, and redshifted by +51(+/-10)km/s relative to the systemic redshift. We interpret this as nebular emission tracing an expanding optically-thin interstellar medium. Both CIV1548,1550 and HeII1640 suggest the presence of hot and massive stars (with a possible faint AGN). The ultraviolet slope is remarkably blue, beta =-2.95 +/- 0.20 (F_lambda=lambda^beta), consistent with a dust-free and young ~<20 Myr galaxy. Line ratios suggest an oxygen abundance 12+log(O/H)<7.8. We are witnessing an early episode of star-formation in which a relatively low NHI and negligible dust attenuation might favor a leakage of ionizing radiation. This galaxy currently represents a unique low-luminosity reference object for future studies of the reionization epoch with JWST.Comment: 7 pages, 4 figures and 1 table; ApJL, accepted for publicatio

Voting Technology, Vote-by-Mail, and Residual Votes in California, 1990-2010

This paper examines how the growth in vote-by-mail and changes in voting technologies led to changes in the residual vote rate in California from 1990 to 2010. We find that in California’s presidential elections, counties that abandoned punch cards in favor of optical scanning enjoyed a significant improvement in the residual vote rate. However, these findings do not always translate to other races. For instance, find that the InkaVote system in Los Angeles has been a mixed success, performing very well in presidential and gubernatorial races, fairly well for ballot propositions, and poorly in Senate races. We also conduct the first analysis of the effects of the rise of vote-by-mail on residual votes. Regardless of the race, increased use of the mails to cast ballots is robustly associated with a rise in the residual vote rate. The effect is so strong that the rise of voting by mail in California has mostly wiped out all the reductions in residual votes that were due to improved voting technologies since the early 1990s

Minding impacting events in a model of stochastic variance

We introduce a generalisation of the well-known ARCH process, widely used for generating uncorrelated stochastic time series with long-term non-Gaussian distributions and long-lasting correlations in the (instantaneous) standard deviation exhibiting a clustering profile. Specifically, inspired by the fact that in a variety of systems impacting events are hardly forgot, we split the process into two different regimes: a first one for regular periods where the average volatility of the fluctuations within a certain period of time is below a certain threshold and another one when the local standard deviation outnumbers it. In the former situation we use standard rules for heteroscedastic processes whereas in the latter case the system starts recalling past values that surpassed the threshold. Our results show that for appropriate parameter values the model is able to provide fat tailed probability density functions and strong persistence of the instantaneous variance characterised by large values of the Hurst exponent is greater than 0.8, which are ubiquitous features in complex systems.Comment: 18 pages, 5 figures, 1 table. To published in PLoS on

A Buoyancy-Based Screen of Drosophila Larvae for Fat-Storage Mutants Reveals a Role for Sir2 in Coupling Fat Storage to Nutrient Availability

Obesity has a strong genetic component, but few of the genes that predispose to obesity are known. Genetic screens in invertebrates have the potential to identify genes and pathways that regulate the levels of stored fat, many of which are likely to be conserved in humans. To facilitate such screens, we have developed a simple buoyancy-based screening method for identifying mutant Drosophila larvae with increased levels of stored fat. Using this approach, we have identified 66 genes that when mutated increase organismal fat levels. Among these was a sirtuin family member, Sir2. Sirtuins regulate the storage and metabolism of carbohydrates and lipids by deacetylating key regulatory proteins. However, since mammalian sirtuins function in many tissues in different ways, it has been difficult to define their role in energy homeostasis accurately under normal feeding conditions. We show that knockdown of Sir2 in the larval fat body results in increased fat levels. Moreover, using genetic mosaics, we demonstrate that Sir2 restricts fat accumulation in individual cells of the fat body in a cell-autonomous manner. Consistent with this function, changes in the expression of metabolic enzymes in Sir2 mutants point to a shift away from catabolism. Surprisingly, although Sir2 is typically upregulated under conditions of starvation, Sir2 mutant larvae survive better than wild type under conditions of amino-acid starvation as long as sugars are provided. Our findings point to a Sir2-mediated pathway that activates a catabolic response to amino-acid starvation irrespective of the sugar content of the diet

CLASSY VII Ly\alpha\ Profiles: The Structure and Kinematics of Neutral Gas and Implications for LyC Escape in Reionization-Era Analogs

Lyman-alpha line profiles are a powerful probe of ISM structure, outflow speed, and Lyman continuum escape fraction. In this paper, we present the Ly$\alpha$ line profiles of the COS Legacy Archive Spectroscopic SurveY, a sample rich in spectroscopic analogs of reionization-era galaxies. A large fraction of the spectra show a complex profile, consisting of a double-peaked Ly$\alpha$ emission profile in the bottom of a damped, Ly$\alpha$ absorption trough. Such profiles reveal an inhomogeneous interstellar medium (ISM). We successfully fit the damped Ly$\alpha$ absorption (DLA) and the Ly$\alpha$ emission profiles separately, but with complementary covering factors, a surprising result because this approach requires no Ly$\alpha$ exchange between high-$N_\mathrm{HI}$ and low-$N_\mathrm{HI}$ paths. The combined distribution of column densities is qualitatively similar to the bimodal distributions observed in numerical simulations. We find an inverse relation between Ly$\alpha$ peak separation and the [O III]/[O II] flux ratio, confirming that the covering fraction of Lyman-continuum-thin sightlines increases as the Ly$\alpha$ peak separation decreases. We combine measurements of Ly$\alpha$ peak separation and Ly$\alpha$ red peak asymmetry in a diagnostic diagram which identifies six Lyman continuum leakers in the CLASSY sample. We find a strong correlation between the Ly$\alpha$ trough velocity and the outflow velocity measured from interstellar absorption lines. We argue that greater vignetting of the blueshifted Ly$\alpha$ peak, relative to the redshifted peak, is the source of the well-known discrepancy between shell-model parameters and directly measured outflow properties. The CLASSY sample illustrates how scattering of Ly$\alpha$ photons outside the spectroscopic aperture reshapes Ly$\alpha$ profiles as the distances to these compact starbursts span a large range.Comment: 40 pages, 19 figures, 5 tables, submitted to ApJ, comments welcom

Tissue-Autonomous Function of Drosophila Seipin in Preventing Ectopic Lipid Droplet Formation

Obesity is characterized by accumulation of excess body fat, while lipodystrophy is characterized by loss or absence of body fat. Despite their opposite phenotypes, these two conditions both cause ectopic lipid storage in non-adipose tissues, leading to lipotoxicity, which has health-threatening consequences. The exact mechanisms underlying ectopic lipid storage remain elusive. Here we report the analysis of a Drosophila model of the most severe form of human lipodystrophy, Berardinelli-Seip Congenital Lipodystrophy 2, which is caused by mutations in the BSCL2/Seipin gene. In addition to reduced lipid storage in the fat body, dSeipin mutant flies accumulate ectopic lipid droplets in the salivary gland, a non-adipose tissue. This phenotype was suppressed by expressing dSeipin specifically within the salivary gland. dSeipin mutants display synergistic genetic interactions with lipogenic genes in the formation of ectopic lipid droplets. Our data suggest that dSeipin may participate in phosphatidic acid metabolism and subsequently down-regulate lipogenesis to prevent ectopic lipid droplet formation. In summary, we have demonstrated a tissue-autonomous role of dSeipin in ectopic lipid storage in lipodystrophy

High Sugar-Induced Insulin Resistance in Drosophila Relies on the Lipocalin Neural Lazarillo

In multicellular organisms, insulin/IGF signaling (IIS) plays a central role in matching energy needs with uptake and storage, participating in functions as diverse as metabolic homeostasis, growth, reproduction and ageing. In mammals, this pleiotropy of action relies in part on a dichotomy of action of insulin, IGF-I and their respective membrane-bound receptors. In organisms with simpler IIS, this functional separation is questionable. In Drosophila IIS consists of several insulin-like peptides called Dilps, activating a unique membrane receptor and its downstream signaling cascade. During larval development, IIS is involved in metabolic homeostasis and growth. We have used feeding conditions (high sugar diet, HSD) that induce an important change in metabolic homeostasis to monitor possible effects on growth. Unexpectedly we observed that HSD-fed animals exhibited severe growth inhibition as a consequence of peripheral Dilp resistance. Dilp-resistant animals present several metabolic disorders similar to those observed in type II diabetes (T2D) patients. By exploring the molecular mechanisms involved in Drosophila Dilp resistance, we found a major role for the lipocalin Neural Lazarillo (NLaz), a target of JNK signaling. NLaz expression is strongly increased upon HSD and animals heterozygous for an NLaz null mutation are fully protected from HSD-induced Dilp resistance. NLaz is a secreted protein homologous to the Retinol-Binding Protein 4 involved in the onset of T2D in human and mice. These results indicate that insulin resistance shares common molecular mechanisms in flies and human and that Drosophila could emerge as a powerful genetic system to study some aspects of this complex syndrome