Weight Vectors of the Basic A_1^(1)-Module and the Littlewood-Richardson Rule

The basic representation of \A is studied. The weight vectors are represented in terms of Schur functions. A suitable base of any weight space is given. Littlewood-Richardson rule appears in the linear relations among weight vectors.Comment: February 1995, 7pages, Using AMS-Te

Decision-making without a brain: how an amoeboid organism solves the two-armed bandit

Several recent studies hint at shared patterns in decision-making between taxonomically distant organisms, yet few studies demonstrate and dissect mechanisms of decision-making in simpler organisms. We examine decision-making in the unicellular slime mould Physarum polycephalum using a classical decision problem adapted from human and animal decision-making studies: the two-armed bandit problem. This problem has previously only been used to study organisms with brains, yet here we demonstrate that a brainless unicellular organism compares the relative qualities of multiple options, integrates over repeated samplings to perform well in random environments, and combines information on reward frequency and magnitude in order to make correct and adaptive decisions. We extend our inquiry by using Bayesian model selection to determine the most likely algorithm used by the cell when making decisions. We deduce that this algorithm centres around a tendency to exploit environments in proportion to their reward experienced through past sampling. The algorithm is intermediate in computational complexity between simple, reactionary heuristics and calculation-intensive optimal performance algorithms, yet it has very good relative performance. Our study provides insight into ancestral mechanisms of decision-making and suggests that fundamental principles of decision-making, information processing and even cognition are shared among diverse biological systems

Optimizing the use of fibrous residues in beef and dairy diets

Increased corn prices over the past decade have altered land use away from traditional forage in favor of corn. Accordingly, beef and dairy producers have had to adopt non-traditional forage resources into their production systems, many of which have become available as a result of increased corn production. Byproducts of the wet and dry milling industries have been used to replace both corn and forage in beef and dairy diets. Byproducts containing corn bran have large amounts of readily digestible hemicellulose. The use of byproducts may increase milk production, ADG, and G:F in dairy, beef growing, and beef finishing diets, respectively. In beef finishing diets, byproducts allow for use of low quality forages or partial replacement of traditional forages with minimal losses in ADG or G:F by formulating for equal NDF concentrations. Corn residues have become more available due to increases in corn acres and yield. The individual plant components (i.e., husk, leaf, stem) vary in fiber digestibility (NDF digestibility estimates = 40.5%, 31.4%, and 0.6% ± 0.8 for husk, leaf, and stalk, respectively). Selectivity for husks and leaves by grazing cattle likely improves their performance. New technologies that allow for selective harvesting of husk and leaf may result in a higher value feed product. Alkaline treatment is another technology that may improve the feeding value of residues. Concentrations of up to 20% harvested corn residue treated with calcium oxide may be included in finishing diets with an average of 2.3% reduction in G:F when diets contain 40% wet or modified distillers grains. Conversely, when untreated corn residues are included in similar finishing diets, G:F may be reduced by 20%. Calcium oxide treated residues included in beef growing diets increases DMI and ADG without significant improvements in G:F. Calcium oxide treatment of corn residues has been evaluated in dairy diets by replacing corn or corn silage with variable results. Harvesting corn silage rather than separate harvest of corn grain and residue may allow for greater total net energy per acre to be captured. The use of wet and modified corn milling byproducts enhances the use of corn silage in finishing diets. While G:F may be reduced, feeding greater concentrations of corn silage may be economical. Efficient use of non-traditional fiber sources, like corn milling by products and corn residue, are critical to the future viability of ruminant animal production

Post-polymerization functionalization of poly(ethylene oxide)–poly(β-6-heptenolactone) diblock copolymers to tune properties and self-assembly

Copolymers were synthesized and functionalized with a variety of moieties to tune self-assembly and install drugs or fluorescent dyes. , Polyester-based amphiphilic block copolymers and their nanoassemblies are of significant interest for a wide range of applications due to the degradability of the polyester block. However, the commonly used polyesters lack functional groups on their backbones, limiting the possibilities to chemically modify these polymers. Described here are new poly(ethylene oxide) (PEO)–poly(β-6-heptenolactone) (PHEL) block copolymers having pendant alkenes at each repeat unit on the PHEL block. First, the self-assembly of these block copolymers in aqueous solution was studied and it was found that they formed solid nanoparticles and vesicles depending on the relative block lengths. Next the alkene moieties of the block copolymer were modified with either hydrophilic or hydrophobic pendant groups using thiol–ene reactions, allowing the hydrophilic mass fractions and consequently the self-assembled morphologies to be tuned, accessing both smaller nanoparticles and cylindrical assemblies. It was also demonstrated that the anti-cancer drug paclitaxel or a fluorescent rhodamine dye could be easily conjugated to the block copolymers and the self-assembly of these conjugates was explored. Overall, the results of this study demonstrate that PEO-PHEL block copolymers can serve as versatile backbones for the preparation of functional, polyester-based materials

The Stability of Radiatively Cooled Jets in Three Dimensions

The effect of optically thin radiative cooling on the Kelvin-Helmholtz instability of three dimensional jets is investigated via linear stability theory and nonlinear hydrodynamical simulation. Two different cooling functions are considered: radiative cooling is found to have a significant effect on the stability of the jet in each case. The wavelengths and growth rates of unstable modes in the numerical simulations are found to be in good agreement with theoretical predictions. Disruption of the jet is found to be sensitive to the precessional frequency at the origin with lower frequencies leading to more rapid disruption. Strong nonlinear effects are observed as the result of the large number of normal modes in three dimensions which provide rich mode-mode interactions. These mode-mode interactions provide new mechanisms for the formation of knots in the flows. Significant structural features found in the numerical simulations appear similar to structures observed on protostellar jets.Comment: 32 pages, 13 figures, figures included in page tota

Distribution of selenium in zebrafish larvae after exposure to organic and inorganic selenium forms

Selenium is an essential micronutrient for many organisms, and in vertebrates has a variety of roles associated with protection from reactive oxygen species. Over the past two decades there have been conflicting reports upon human health benefits and detriments arising from consumption of selenium dietary supplements. Thus, early studies report a decrease in the incidence of certain types of cancer, whereas subsequent studies did not observe any anti-cancer effect, and adverse effects such as increased risks for type 2 diabetes have been reported. A possible contributing factor may be that different chemical forms of selenium were used in different studies. Using larval stage zebrafish (Danio rerio) as a model organism, we report a comparison of the toxicities and tissue selenium distributions of four different chemical forms of selenium. We find that the organic forms of selenium tested (Se-methyl-l-selenocysteine and l-selenomethionine) show considerably more toxicity than inorganic forms (selenite and selenate), and that this appears to be correlated with the level of bioaccumulation. Despite differences in concentrations, the tissue specific pattern of selenium accumulation was similar for the chemical forms tested; selenium was found to be highly concentrated in pigment (melanin) containing tissues especially for the organic selenium treatments, with lower concentrations in eye lens, yolk sac and heart. These results suggest that pigmented tissues might serve as a storage reservoir for selenium. © 2016 The Royal Society of Chemistry

Sorting Strategies for Long Yearling Cattle Grown in an Extensive Forage Utilization Beef Production System

One hundred sixty English-cross steers (244 kg, SD=23 kg) were used in each yr of a 2-yr study to determine effects of sorting on performance, carcass characteristics, variability, and profitability in a long yearling system utilizing ranch-source calves. Steers were back grounded during winter then grazed smooth brome-grass pastures followed by warm season native range prior to entering the feedlot in the fall. Steers were stratified by BW and allotted to 1 of 4 treatments: 1) 40 head sorted by pre-grazing BW where heavy steers entered the feedlot in July (PST), 2) 40 head sorted by BW entering the feedlot (FDL), 3) 60 head sorted by BW and fat thickness at the end of the feeding period (IND), and 4) 20 head that were not sorted (UNS). No differences were observed for performance during back-grounding or grazing phases (P \u3e 0.30). Cattle receiving PST sorting weighed less entering the feedlot and consumed less feed with less feedlot ADG compared to other treatments (P \u3c 0.05). No differences in feed efficiencies were detected (P = 0.84). Cattle receiving PST sorting had greater marbling scores (P \u3c 0.05) and less variation in BW upon feedlot entry which resulted in less variation in carcass weight compared with UNS (P \u3c 0.05). Cattle sorted by BW entering the feedlot tended (P = 0.08) to have less variation in carcass weight compared with UNS. There were no differences in carcass weight or profitability when calculated on either a live or value basis. No sorting strategy increased carcass weight, reduced discounts for overweight or corpulent carcasses, or improved profitability over UNS

Comparison of Performance and Economics of a Long-yearling and Calf-fed System

Performance and economics of calf feeding and feeding long-yearlings was compared from University of Nebraska research conducted from 1996 to 2004. All calves in these studies were spring born and purchased the subsequent fall. The heaviest calves (292 ± 5 kg) were placed into the feedlot and fed an average of 168 d (calf-feds), whereas the lighter calves (239 ± 5 kg) were placed into a long-yearling system consisting of corn residue grazing followed by summer grazing before entering the feedlot for finishing. Long-yearlings were fed in the feedlot for an average of 90 d. At the beginning of the finishing period, long-yearlings were 143 kg heavier than calf-feds (P \u3c 0.01). Although daily DMI was greater for long-yearlings (P \u3c 0.01), calf-feds consumed more total DM during finishing (P \u3c 0.01). Long-yearlings had greater ADG compared with calf-feds during finishing (P \u3c 0.01); however, calf-feds were 18.7% more efficient (P \u3c 0.01). Long-yearlings were 38 kg heavier (P \u3c 0.01) than calf-feds and had 24 kg heavier hot carcass weight (P \u3c 0.01). Quality grade was not affected by production system (P \u3e 0.10); however, calf-feds had 0.15 cm greater fat thickness (P \u3c 0.01). Long-yearlings were more profitable than calf-feds (P \u3c 0.01) due to lower feed cost (P \u3c 0.01), yardage (P \u3c 0.01), and initial animal cost (P \u3c 0.01). However, long-yearlings had higher interest cost (P \u3c 0.01) and total cost (P = 0.02). Long-yearlings produced greater final BW leading to an improvement in profitability compared with calf-feds

Sorting Strategies for Long Yearling Cattle Grown in an Extensive Forage Utilization Beef Production System

One hundred sixty English-cross steers (244 kg, SD=23 kg) were used in each yr of a 2-yr study to determine effects of sorting on performance, carcass characteristics, variability, and profitability in a long yearling system utilizing ranch-source calves. Steers were back grounded during winter then grazed smooth brome-grass pastures followed by warm season native range prior to entering the feedlot in the fall. Steers were stratified by BW and allotted to 1 of 4 treatments: 1) 40 head sorted by pre-grazing BW where heavy steers entered the feedlot in July (PST), 2) 40 head sorted by BW entering the feedlot (FDL), 3) 60 head sorted by BW and fat thickness at the end of the feeding period (IND), and 4) 20 head that were not sorted (UNS). No differences were observed for performance during back-grounding or grazing phases (P \u3e 0.30). Cattle receiving PST sorting weighed less entering the feedlot and consumed less feed with less feedlot ADG compared to other treatments (P \u3c 0.05). No differences in feed efficiencies were detected (P = 0.84). Cattle receiving PST sorting had greater marbling scores (P \u3c 0.05) and less variation in BW upon feedlot entry which resulted in less variation in carcass weight compared with UNS (P \u3c 0.05). Cattle sorted by BW entering the feedlot tended (P = 0.08) to have less variation in carcass weight compared with UNS. There were no differences in carcass weight or profitability when calculated on either a live or value basis. No sorting strategy increased carcass weight, reduced discounts for overweight or corpulent carcasses, or improved profitability over UNS