Constructed Wetland Treatment Systems for Water Quality Improvement

2010 S.C. Water Resources Conferences - Science and Policy Challenges for a Sustainable Futur

Biennial wormwood (Artemisia biennis) competition with soybean (Glycine max)

Biennial wormwood has become a serious weed of several crops in the northern Great Plains of the United States and Prairie Provinces of Canada. Greenhouse replacement series experiments were conducted to investigate the effects of watering regime (stressed and non-stressed) and nitrogen rate (50, 100, 150, and 200 mg kg-1 of soil) on competition between soybean and biennial wormwood. Soybean height was reduced after 9 weeks of competition with biennial wormwood compared with soybean grown in monoculture, whereas biennial wormwood plants were taller when grown with soybean than in monoculture. The change in plant height indicated that biennial wormwood height was increased due to interspecific competition, whereas soybean height was reduced. When moisture was limited, the relative yield of biennial wormwood was greater than that of soybean, indicating that biennial wormwood was more aggressive than soybean. Soybean growth was unaffected by an increase in nitrogen rate, whereas biennial wormwood fresh weight was 30% greater when the nitrogen rate was increased from 50 to 200 mg kg-1. Biennial wormwood aggressivity tended to increase as the nitrogen rate was increased from 50 to 200 mg kg-1. Overall results suggest that the negative impact of biennial wormwood competition with soybeans under field conditions may increase when soil moisture is limited and nitrogen fertility is increased.L'armoise bisannuelle est devenue une importante mauvaise herbe pour plusieurs cultures dans le nord des Grandes Plaines des États-Unis et dans les provinces des Prairies au Canada. Des expériences avec des séries de remplacement ont été menées en serre afin d'étudier les effets du régime d'alimentation en eau (stressant et non stressant) et de la quantité d'azote (50, 100, 150 et 200 mg kg-1 de sol) sur la compétition entre le soja et l'armoise bisannuelle. Après 9 semaines de compétition avec l'armoise bisannuelle, la taille du soja était inférieure à celle du soja en monoculture alors que l'armoise bisannuelle était plus grande en présence de soja qu'en monoculture. Les différences dans la taille des plantes montrent que la compétition interspécifique a fait augmenter celle de l'armoise bisannuelle et diminuer celle du soja. Lorsque l'eau était un facteur limitatif, le rendement relatif de l'armoise bisannuelle était plus élevé que celui du soja, ce qui montre que l'armoise bisannuelle était plus agressive que le soja. L'augmentation de la quantité d'azote n'a pas affecté la croissance du soja. Cependant, le poids de matière fraîche de l'armoise bisannuelle était 30 % plus élevé lorsque la quantité d'azote est passée de 50 à 200 mg kg-1. L'agressivité de l'armoise bisannuelle a eu tendance à augmenter lorsque la quantité d'azote est passée de 50 à 200 mg kg-1. Globalement, les résultats montrent que les impacts négatifs de la compétition entre l'armoise bisannuelle et le soja, dans des conditions naturelles, peuvent s'accroître lorsque l'eau manque et que la quantité d'azote disponible augmente

Constructed Treatment Wetlands and Water Effect Ratio Study to Achieve Storm Water Compliance at Savannah River Site

2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur

Addressing Math Deficits to Improve Chemistry Success

The brain solves problems in structures termed "working memory." Between 2001 and 2010, cognitive experiments verified that at each step when solving a problem, working memory can hold only a few small elements of knowledge that are not well-memorized. One implication of this limit is that students must rely almost exclusively on the application of memorized facts and algorithms when solving mathematical or scientific calculations. Unfortunately, since 1990, K-12 math standards in most U.S. states assumed that with access to calculators and computers, memorization in math could be de-emphasized. As a result, many students have deficits in “automaticity” in the recall of math that is necessary for chemistry. This paper will include evidence that if math fundamentals are moved into memory as preparation for a chemistry topic, student success in first-year chemistry improves substantially

The \u3cem\u3elet-7\u3c/em\u3e MicroRNA Family Members \u3cem\u3emir\u3c/em\u3e-48, \u3cem\u3emir\u3c/em\u3e-84, and mir-241 Function Together to Regulate Developmental Timing in \u3cem\u3eCaenorhabditis elegans\u3c/em\u3e

The microRNA let-7 is a critical regulator of developmental timing events at the larval-to-adult transition in C. elegans. Recently, microRNAs with sequence similarity to let-7 have been identified. We find that doubly mutant animals lacking the let-7 family microRNA genes mir-48 and mir-84 exhibit retarded molting behavior and retarded adult gene expression in the hypodermis. Triply mutant animals lacking mir-48, mir-84, and mir-241 exhibit repetition of L2-stage events in addition to retarded adult-stage events. mir-48, mir-84, and mir-241 function together to control the L2-to-L3 transition, likely by base pairing to complementary sites in the hbl-1 3′ UTR and downregulating hbl-1 activity. Genetic analysis indicates that mir-48, mir-84, and mir-241 specify the timing of the L2-to-L3 transition in parallel to the heterochronic genes lin-28 and lin-46. These results indicate that let-7 family microRNAs function in combination to affect both early and late developmental timing decisions

Polarization-based Tests of Gravity with the Stochastic Gravitational-Wave Background

The direct observation of gravitational waves with Advanced LIGO and Advanced Virgo offers novel opportunities to test general relativity in strong-field, highly dynamical regimes. One such opportunity is the measurement of gravitational-wave polarizations. While general relativity predicts only two tensor gravitational-wave polarizations, general metric theories of gravity allow for up to four additional vector and scalar modes. The detection of these alternative polarizations would represent a clear violation of general relativity. The LIGO-Virgo detection of the binary black hole merger GW170814 has recently offered the first direct constraints on the polarization of gravitational waves. The current generation of ground-based detectors, however, is limited in its ability to sensitively determine the polarization content of transient gravitational-wave signals. Observation of the stochastic gravitational-wave background, in contrast, offers a means of directly measuring generic gravitational-wave polarizations. The stochastic background, arising from the superposition of many individually unresolvable gravitational-wave signals, may be detectable by Advanced LIGO at design-sensitivity. In this paper, we present a Bayesian method with which to detect and characterize the polarization of the stochastic background. We explore prospects for estimating parameters of the background, and quantify the limits that Advanced LIGO can place on vector and scalar polarizations in the absence of a detection. Finally, we investigate how the introduction of new terrestrial detectors like Advanced Virgo aid in our ability to detect or constrain alternative polarizations in the stochastic background. We find that, although the addition of Advanced Virgo does not notably improve detection prospects, it may dramatically improve our ability to estimate the parameters of backgrounds of mixed polarization.Comment: 24 pages, 20 figures; Accepted by PRX. This version includes major changes in response to referee comments and corrects an error in Eq. E

Crystal structure of the cowpox virus-encoded NKG2D ligand OMCP

The NKG2D receptor is expressed on the surface of NK, T, and macrophage lineage cells and plays an important role in antiviral and antitumor immunity. To evade NKG2D recognition, herpesviruses block the expression of NKG2D ligands on the surface of infected cells using a diverse repertoire of sabotage methods. Cowpox and monkeypox viruses have taken an alternate approach by encoding a soluble NKG2D ligand, the orthopoxvirus major histocompatibility complex (MHC) class I-like protein (OMCP), which can block NKG2D-mediated cytotoxicity. This approach has the advantage of targeting a single conserved receptor instead of numerous host ligands that exhibit significant sequence diversity. Here, we show that OMCP binds the NKG2D homodimer as a monomer and competitively blocks host ligand engagement. We have also determined the 2.25-Å-resolution crystal structure of OMCP from the cowpox virus Brighton Red strain, revealing a truncated MHC class I-like platform domain consisting of a beta sheet flanked with two antiparallel alpha helices. OMCP is generally similar in structure to known host NKG2D ligands but has notable variations in regions typically used to engage NKG2D. Additionally, the determinants responsible for the 14-fold-higher affinity of OMCP for human than for murine NKG2D were mapped to a single loop in the NKG2D ligand-binding pocket