On December 22, 2008 a dike containing coal fly ash from the Tennessee Valley Authority Kingston Fossil Plant near Kingston Tennessee USA failed and resulted in the largest coal ash spill in U.S. ...history. Coal ash, a by-product of coal combustion, is known to contain multiple contaminants of concern, including arsenic and selenium. The purpose of this study was to investigate species differences in the bioaccumulation of arsenic and selenium and potential factors contributing to these differences (i.e., trophic dynamics and gut pH) in the vicinity of the Kingston coal ash spill. Elevated levels of arsenic and selenium were observed in various tissues of largemouth bass, white crappie, bluegill and redear sunfish from sites associated with the Kingston coal ash spill. Highest concentrations of selenium were found in redear sunfish with liver concentrations as high as 24.83mg/kg dry weight and ovary concentrations up to 10.40mg/kg dry weight at coal ash-associated sites. Investigations into the gut pH and trophic dynamics of redear sunfish and bluegill demonstrated a large difference in the gut physiology between these two species. Redear sunfish stomach and intestinal pH was found to be 1.1 and 0.16 pH units higher than in bluegill, respectively. In addition, fish from coal ash-associated sites showed enrichment differences (15N and 13C) compared to no ash sites, indicating differences in food web dynamics between sites. These results imply the incorporation of coal ash-associated compounds into local food webs and/or a shift in diet at ash sites compared to the no ash reference sites. Based on these results, further investigation into a broader food web at ash-associated sites is warranted.
► Environmental investigation of the largest coal ash spill in US history. ► Selenium and arsenic bioaccumulation is elevated in fish at coal ash-associated sites. ► Trophic dynamics (stable isotopes C and N) are shifted at coal ash-associated sites. ► Physiological differences in the gut of redear sunfish and bluegill exist. ► Potential evidence of coal ash constituents being incorporated into the food chain.
Evidence for a B-s(0)pi(+/-) State Askew, A.; Aushev, V.; Avila, C. ...
Physical review letters,
07/2016, Letnik:
117, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We report evidence for a narrow structure, X(5568), in the decay sequence X(5568) -> B-s(0)pi(+/-), B-s(0) -> J/psi phi, J/psi -> mu(+)mu(-), phi -> K+K-. This is evidence for the first ...instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m = 5567.8 +/- 2.9(stat)(-1.9)(+0.9) (syst) MeV/c(2) and Gamma = 21.9 +/- 6.4(stat)(-2.5)(+5.0) (syst) MeV/c(2). If the decay is X(5568) -> B-s*pi(+/-). B-s(0)gamma pi(+/-) with an unseen gamma, m(X(5568)) will be shifted up by m(B-s*) - m(B-s(0)) similar to 49 MeV/c(2). This measurement is based on 10.4 fb(-1) of p (p) over bar collision data at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
A 4.1 million m
3
coal ash release into the Emory and Clinch rivers in December 2008 at the Tennessee Valley Authority’s Kingston Fossil Plant in east Tennessee, USA, prompted a long-term, ...large-scale biological monitoring effort to determine if there are chronic effects of this spill on resident biota. Because of the magnitude of the ash spill and the potential for exposure to coal ash-associated contaminants e.g., selenium (Se), arsenic (As), and mercury (Hg) which are bioaccumulative and may present human and ecological risks, an integrative, bioindicator approach was used. Three species of fish were monitored—bluegill (
Lepomis macrochirus
), redear sunfish (
L. microlophus
), and largemouth bass (
Micropterus salmoides
)—at ash-affected and reference sites annually for 5 years following the spill. On the same individual fish, contaminant burdens were measured in various tissues, blood chemistry parameters as metrics of fish health, and various condition and reproduction indices. A multivariate statistical approach was then used to evaluate relationships between contaminant bioaccumulation and fish metrics to assess the chronic, sub-lethal effects of exposure to the complex mixture of coal ash-associated contaminants at and around the ash spill site. This study suggests that while fish tissue concentrations of some ash-associated contaminants are elevated at the spill site, there was no consistent evidence of compromised fish health linked with the spill. Further, although relationships between elevated fillet burdens of ash-associated contaminants and some fish metrics were found, these relationships were not indicative of exposure to coal ash or spill sites. The present study adds to the weight of evidence from prior studies suggesting that fish populations have not incurred significant biological effects from spilled ash at this site: findings that are relevant to the current national discussions on the safe disposal of coal ash waste.
Community structure is the observable outcome of numerous processes. We conducted a laboratory experiment using a microbial model system to disentangle effects of nutrient enrichment, dispersal, and ...predation on prey species richness and predator abundance at local and metacommunity scales. Prey species included: Chilomonas sp., Colpidium striatum, Colpoda cucullus, Paramecium tetraurelia, P. caudatum, Philodina sp., Spirostomum sp., Tetrahymena thermophila, and Uronema sp., and Stentor coeruleus was the predator used. We hypothesized that: (1) increased basal resources should maintain greater species richness and higher predator abundance; (2) dispersal should maintain greater species richness; and (3) predation should reduce species richness, especially in the high resource treatments relative to no-predator treatments. Our results support all three hypotheses. Further, we show that dispersal affects richness at the local community scale but not at the metacommunity scale. However, predation seems to have major effects at both the local and metacommunity scale. Overall, our results show that effects of resource enrichment, dispersal, and predation were mostly additive rather than interactive, indicating that it may be sometimes easier to understand their effects than generally thought due to complex interactive effects.
We present evidence for the exotic charged charmoniumlike state Zc±(3900) decaying to J/ψπ± in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent J/ψπ+π− system ...in the invariant-mass range 4.2–4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4 fb−1 of pp¯ collision data collected by the D0 experiment at the Fermilab Tevatron collider.
Hydrokinetic energy is proposed as an environmentally preferred means of generating electricity from river and tidal currents. To resolve environmental concerns, it is important to investigate ...potential effects on aquatic organisms from the electromagnetic fields (EMFs) that are created by underwater generators and transmission cables. We evaluated the behavioral responses of some representative freshwater fishes to static and variable EMFs in a series of laboratory experiments. Fish were exposed for 46 h to a static (DC) EMF with a permanent bar magnet or to a variable (AC) EMF with an electromagnet. Fish locations were recorded with a digital imaging system, and changes in activity level and distribution relative to the magnet position were quantified at 5-min intervals. Experiments with Fathead Minnow Pimephales promelas , Redear Sunfish Lepomis microlophus , Striped Bass Morone saxatilis , Lake Sturgeon Acipenser fulvescens , and Channel Catfish Ictalurus punctatus produced mixed results. Except for Fathead Minnow, there was no effect on fish activity level. Only Redear Sunfish and Channel Catfish exhibited a change in distribution relative to the position of the magnet, with both species showing an apparent attraction to the EMF source. In a separate experiment, rapid behavioral responses of Paddlefish Polyodon spathula and Lake Sturgeon to the onset of an AC field were recorded with high-speed video. Paddlefish did not react to a variable, 60-Hz magnetic field (i.e., like that emitted by an AC generator or cable), but Lake Sturgeon consistently responded with a variety of altered swimming behaviors. These results will be useful for positioning cables or generators to minimize interactions with EMF-sensitive species. Received August 10, 2012; accepted February 16, 2013
U6 small nuclear RNA (snRNA) is an essential component of the spliceosome, the ribonucleoprotein complex that carries out the splicing of pre-mRNAs. The precise function of U6 RNA is unknown, but it ...has been proposed to participate directly in catalysis of the splicing reaction. We present biochemical and genetic evidence for an intramolecular stem/loop structure in the 3' half of U6 RNA of the yeast Saccharomyces cerevisiae that is mutually exclusive with the intermolecular base-pairing between U6 RNA and U4 snRNA. Strains with mutations that stabilize the U6 RNA 3'-intramolecular stem exhibit cold-sensitive growth and accumulate free U4 RNA, indicative of a block in U4/U6 snRNP assembly. The cold sensitivity can be partially suppressed by overexpression of U4 RNA. Mutations that disrupt base-pairing in the intramolecular 3' stem and mutations elsewhere in U6 RNA also suppress the growth defect. We conclude that a large conformational switch, involving melting of the U6 RNA 3' stem, is required for U4/U6 snRNP assembly. We hypothesize that formation of the U6 RNA intramolecular 3' stem after U4 RNA leaves the assembled spliceosome serves to activate U6 RNA for splicing by juxtaposing regions in U6 RNA that interact with U2 small nuclear RNA.
Most general surgeons involved in breast cancer care have limited experience with phyllodes tumors. We analyzed a comprehensive database incorporating 8567 breast cancer cases treated surgically in ...the Tulsa, Oklahoma, region between 1969 and 1993. This yielded 32 cases of phyllodes tumors (0.37%) in 31 patients. The median age was 57 years (range, 18–91). There were 9 low-grade (28%), 2 intermediate-grade (6%), and 21 high-grade (66%) lesions. Size distribution consisted of 23 (72%) lesions 5 cm or less and 9 (28%) greater than 5 cm (mean, 3; range, 1.2–17.5 cm). Of 137 resected nodes in 13 patients, none were positive for metastatic disease. Surgical management consisted of wide excision or mastectomy. No patients received adjuvant chemoradiation therapy. The disease-free, locoregional disease-free, and overall mean survival rates were 80, 81, and 97 months, respectively. Ten-year disease-free survival (DFS), locoregional disease-free survival (LRDFS), and overall survival (OS) rates were 66, 72, and 55 per cent, respectively. Although there was a tendency toward a higher rate of locoregional recurrences and metastases with high-grade lesions, this was not statistically significant and did not affect DFS, LRDFS, or OS rates. Similarly, size of lesion did not affect DFS, LRDFS, or OS rates. Three patients (9.6%) had metastatic disease at presentation, and a further two (6.4%) developed metastases during follow-up. Overall, nine (28.1%) recurrences developed in eight patients, seven locoregional and two distant. Four patients (12.9%) died with evidence of disease. These findings indicate prolonged survival in this patient population with cystosarcoma phyllodes. Wide local excision of primary and recurrent lesions remains the mainstay of therapy. Neither regional lymph node dissection nor adjuvant chemoradiation adds significant benefit.
Passage of fishes through hydropower turbines and water pumping stations may cause mortal injury as the result of exposure to blade strike impact. Laboratory trials of simulated blade strike on two ...morphologically distinct fishes, American eel (
Anguilla rostrata
) and bluegill sunfish (
Lepomis macrochirus
) were undertaken to assess injury and mortality rates. We hypothesized that bluegill would have comparable rates of injury and mortality to other laterally compressed fishes while anguilliform American eel would be more resistant to injury. American eel had low observed mortality rates at the highest velocity tested (13.6 m/s), but many fish were observed with vertebral fractures which we categorized as functionally dead individuals. Bluegill were more susceptible to blade strike with high rates of mortality regardless of blade thickness, velocity, or impact conditions (location, angle, or fish orientation). These data have broadened our understanding of the range of responses among entrained fishes exposed to blade strike and represent species with low (American eel) and high (bluegill) susceptibility to injury and mortality. Our blade strike data can help inform safer turbine designs or prioritization of pumps that minimize traumatic injury and mortality of fishes during non-volitional passage through hydropower turbines or water pumping stations.
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