A tiling approach to eight identities of Rogers

AbstractBeginning in 1893, L.J. Rogers produced a collection of papers in which he considered series expansions of infinite products. Over the years, his identities have been given a variety of partition-theoretic interpretations and proofs. These existing combinatorial techniques, however, do not highlight the similarities and the subtle differences seen in so many of these remarkable identities. It is the goal of this paper to present a new combinatorial approach that unifies numerous q-series identities. The eight identities of Rogers that appear in G.E. Andrews’ 1986 CBMS monograph on q-series will serve as a basis for the collection of identities studied in this paper

Yield and Production Costs for Three Potential Dedicated Energy Crops in Mississippi and Oklahoma Environments

The objective of this paper is to determine production costs of switchgrass, eastern gammagrass, and giant miscanthus using Mississippi and Oklahoma data. Production costs were computed using a standard enterprise budgeting approach by species and method of harvest. Results indicate cost difference across species and method of harvest.Yield and Cost, biomass species, Crop Production/Industries, Resource /Energy Economics and Policy,

Prophylactic properties of biofloc- or Nile tilapia-conditioned water against Vibrio parahaemolyticus infection of whiteleg shrimp (Penaeus vannamei)

Isolates of Vibrio parahaemolyticus (VpAHPND) that carry a plasmid encoding two Pir-like toxins cause acute hepatopancreatic necrosis disease (AHPND), a disease that has caused devastating economic losses to the shrimp industry, particularly in Asia. However, lower prevalence of AHPND infection has been associated with farms that operate with biofloc or lower salinity culture water. Therefore, the aim of this present study was to investigate the effects of biofloc and Nile tilapia (Oreochromis niloticus)-conditioned water prepared at different culture water salinities on survival of whiteleg shrimp (Penaeus vannamei) bath-challenged experimentally with VpAHPND. First, groups of shrimp were bath-challenged with VpAHPND in clear 15 ppt seawater (CW) or in the presence of a pre-cultured biofloc at 25%, 50% and 100% (v/v). Survival during 96 h post-challenge was significantly greater in groups cultured in 50% and 100% biofloc (p

Computational modelling of solvent effects in a prolific solvatomorphic porous organic cage

Crystal structure prediction methods can enable the in silico design of functional molecular crystals, but solvent effects can have a major influence on relative lattice energies sometimes thwarting predictions. This is particularly true for porous solids, where solvent included in the pores can have an important energetic contribution. Here we present a Monte Carlo solvent insertion procedure for predicting the solvent filling of porous structures from crystal structure prediction landscapes, tested using a highly solvatomorphic porous organic cage molecule, CC1. We use this method to rationalise the fact that the predicted global energy minimum structure for CC1 is never observed from solvent crystallisation. We also explain the formation of three different solvatomorphs of CC1 from three structurally-similar chlorinated solvents. Calculated solvent stabilisation energies are found to correlate with experimental results from thermogravimetric analysis, suggesting a future computational framework for a priori materials design that includes solvation effects

Mining predicted crystal structure landscapes with high throughput crystallisation: old molecules, new insights

Organic molecules tend to close pack to form dense structures when they are crystallized from organic solvents. Porous molecular crystals defy this rule: they typically crystallize with lattice solvent in the interconnected pores. However, the design and discovery of such structures is often challenging and time consuming, in part because it is difficult to predict solvent effects on crystallization. Here, we combine crystal structure prediction (CSP) with a high-throughput crystallization screening method to accelerate the discovery of stable hydrogen-bonded frameworks. We exemplify this strategy by finding new phases of two well-studied molecules in a computationally targeted way. Specifically, we find a new porous polymorph of trimesic acid, δ-TMA, that has a guest free hexagonal pore structure, as well as three new solvent-stabilized diamondoid frameworks of adamantane-1,3,5,7-tetracarboxylic acid (ADTA)

The Halo Occupation Distribution: Towards an Empirical Determination of the Relation Between Galaxies and Mass

We investigate galaxy bias in the framework of the ``Halo Occupation Distribution'' (HOD), which defines the bias of a population of galaxies by the conditional probability P(N|M) that a dark matter halo of virial mass M contains N galaxies, together with prescriptions that specify the relative spatial and velocity distributions of galaxies and dark matter within halos. By populating the halos of a cosmological N-body simulation using a variety of HOD models, we examine the sensitivity of different galaxy clustering statistics to properties of the HOD. The galaxy correlation function responds to different aspects of P(N|M) on different scales. Obtaining the observed power-law form of xi(r) requires rather specific combinations of HOD parameters, implying a strong constraint on the physics of galaxy formation; the success of numerical and semi-analytic models in reproducing this form is entirely non-trivial. Other clustering statistics such as the galaxy-mass correlation function, the bispectrum, the void probability function, the pairwise velocity dispersion, and the group multiplicity function are sensitive to different combinations of HOD parameters and thus provide complementary information about galaxy bias. We outline a strategy for determining the HOD empirically from redshift survey data. This method starts from an assumed cosmological model, but we argue that cosmological and HOD parameters will have non-degenerate effects on galaxy clustering, so that a substantially incorrect cosmological model will not reproduce the observations for any choice of HOD. Empirical determinations of the HOD as a function of galaxy type from the 2dF and SDSS redshift surveys will provide a detailed target for theories of galaxy formation, insight into the origin of galaxy properties, and sharper tests of cosmological models.Comment: 60 pages + 21 eps figures. Replaced with accepted ApJ version. Minor changes + added reference

Passing the Panda Standard: A TAD Off the Mark?

Tilapia, a tropical freshwater fish native to Africa, is an increasingly important global food commodity. The World Wide Fund for Nature (WWF), a major environmental nongovernmental organization, has established stakeholder dialogues to formulate farm certification standards that promote ‘‘responsible’’ culture practices. As a preface to its ‘‘tilapia aquaculture dialogue,’’ the WWF for Nature commissioned a review of potential certification issues, later published as a peer-reviewed article. This article contends that both the review and the draft certification standards subsequently developed fail to adequately integrate critical factors governing the relative sustainability of tilapia production and thereby miss more significant issues related to resource-use efficiency and the appropriation of ecosystem space and services. This raises a distinct possibility that subsequent certification will promote intensive systems of tilapia production that are far less ecologically benign than existing widely practiced semiintensive alternatives. Given the likely future significance of this emergent standard, it is contended that a more holistic approach to certification is essential

A collagen-hydroxyapatite scaffold allows for binding and co-delivery of recombinant bone morphogenetic proteins and bisphosphonates.

An emerging paradigm in orthopedics is that a bone-healing outcome is the product of the anabolic (bone-forming) and catabolic (bone-resorbing) outcomes. Recently, surgical and tissue engineering strategies have emerged that combine recombinant human bone morphogenetic proteins (rhBMPs) and bisphosphonates (BPs) in order to maximize anabolism and minimize catabolism. Collagen-based scaffolds that are the current surgical standard can bind rhBMPs, but not BPs. We hypothesized that a biomimetic collagen-hydroxyapatite (CHA) scaffold would bind both agents and produce superior in vivo outcomes. Consistent with this concept, in vitro elution studies utilizing rhBMP-2 ELISA assays and scintillation counting of (14)C-radiolabeled zoledronic acid (ZA) confirmed delayed release of both agents from the CHA scaffold. Next, scaffolds were tested for their capacity to form ectopic bone after surgical implantation into the rat hind limb. Using CHA, a significant 6-fold increase in bone volume was seen in rhBMP-2/ZA groups compared to rhBMP-2 alone, confirming the ability of ZA to enhance rhBMP-2 bone formation. CHA scaffolds were found to be capable of generating mineralized tissue in the absence of rhBMP-2. This study has implications for future clinical treatments of critical bone defects. It demonstrates the relative advantages of co-delivering anabolic and anti-catabolic agents using a multicomponent scaffold system

Individual, Environmental, and Meteorological Predictors of Daily Personal Ultraviolet Radiation Exposure Measurements in a United States Cohort Study

Background Individual exposure to ultraviolet radiation (UVR) is challenging to measure, particularly for diseases with substantial latency periods between first exposure and diagnosis of outcome, such as cancer. To guide the choice of surrogates for long-term UVR exposure in epidemiologic studies, we assessed how well stable sun-related individual characteristics and environmental/meteorological factors predicted daily personal UVR exposure measurements. Methods We evaluated 123 United States Radiologic Technologists subjects who wore personal UVR dosimeters for 8 hours daily for up to 7 days (N = 837 days). Potential predictors of personal UVR derived from a self-administered questionnaire, and public databases that provided daily estimates of ambient UVR and weather conditions. Factors potentially related to personal UVR exposure were tested individually and in a model including all significant variables. Results The strongest predictors of daily personal UVR exposure in the full model were ambient UVR, latitude, daily rainfall, and skin reaction to prolonged sunlight (R2 = 0.30). In a model containing only environmental and meteorological variables, ambient UVR, latitude, and daily rainfall were the strongest predictors of daily personal UVR exposure (R2 = 0.25). Conclusions In the absence of feasible measures of individual longitudinal sun exposure history, stable personal characteristics, ambient UVR, and weather parameters may help estimate long-term personal UVR exposure