Arkansas Lepidoptera Survey: A Preliminary Check List of Arkansas Species

The mission of the Arkansas Lepidoptera Survey is to enhance the fundamental knowledge of butterflies, skippers, and moths in Arkansas. To achieve this mission, its objectives include developing a reference collection of Arkansas Lepidoptera and maintaining a current check list of present, historical and accidental species in Arkansas. The following list includes 1360 species representing 57 families. It was compiled from original field collecting, literature review, and analysis of museum specimens. The Arkansas Lepidoptera Survey established a reference collection of Arkansas butterflies, skippers and moths located in McEver Hall on the Arkansas Tech University campus. This collection currently contains 567 species representing 28 families

Trade Flows and Wage Premiums: Does Who or What Matter?

In this paper we investigate relationships between trade, wages, and the rewards to skill for U.S. workers during the period 1981 - 92. We measure U.S. trade flows with three groups of trading partners -- industrial countries, newly industrial countries, and primary producers -- and we estimate the correlation of these trade flows with several types of wage premiums, using conditioning methods that separate pure wage premiums from the return to education industry by industry. We find that greater U.S. trade with newly industrializing countries is associated with increased rewards to skill and reduced rewards to pure labor, consistent with heightened wage inequality and distributional conflict. The opposite is usually true of greater trade with traditional industrial countries. Our interpretation of these results rests on two models. One is a model of North-North intraindustry trade in differentiated, skill-intensive intermediate goods ( horizontal' exchange) and North-South intraindustry trade in intermediates for finished manufactures ( vertical' exchange). The second is a simple model of industry wage premiums that are rewards for loyalty, firm-specific knowledge, or (dis)amenities, in which we posit different premiums for skilled and less-skilled workers whose labor markets are segmented from one another.

A Grassmann integral equation

The present study introduces and investigates a new type of equation which is called Grassmann integral equation in analogy to integral equations studied in real analysis. A Grassmann integral equation is an equation which involves Grassmann integrations and which is to be obeyed by an unknown function over a (finite-dimensional) Grassmann algebra G_m. A particular type of Grassmann integral equations is explicitly studied for certain low-dimensional Grassmann algebras. The choice of the equation under investigation is motivated by the effective action formalism of (lattice) quantum field theory. In a very general setting, for the Grassmann algebras G_2n, n = 2,3,4, the finite-dimensional analogues of the generating functionals of the Green functions are worked out explicitly by solving a coupled system of nonlinear matrix equations. Finally, by imposing the condition G[{\bar\Psi},{\Psi}] = G_0[{\lambda\bar\Psi}, {\lambda\Psi}] + const., 0<\lambda\in R (\bar\Psi_k, \Psi_k, k=1,...,n, are the generators of the Grassmann algebra G_2n), between the finite-dimensional analogues G_0 and G of the (``classical'') action and effective action functionals, respectively, a special Grassmann integral equation is being established and solved which also is equivalent to a coupled system of nonlinear matrix equations. If \lambda \not= 1, solutions to this Grassmann integral equation exist for n=2 (and consequently, also for any even value of n, specifically, for n=4) but not for n=3. If \lambda=1, the considered Grassmann integral equation has always a solution which corresponds to a Gaussian integral, but remarkably in the case n=4 a further solution is found which corresponds to a non-Gaussian integral. The investigation sheds light on the structures to be met for Grassmann algebras G_2n with arbitrarily chosen n.Comment: 58 pages LaTeX (v2: mainly, minor updates and corrections to the reference section; v3: references [4], [17]-[21], [39], [46], [49]-[54], [61], [64], [139] added

Overview of mathematical approaches used to model bacterial chemotaxis II: bacterial populations

We review the application of mathematical modeling to understanding the behavior of populations of chemotactic bacteria. The application of continuum mathematical models, in particular generalized Keller–Segel models, is discussed along with attempts to incorporate the microscale (individual) behavior on the macroscale, modeling the interaction between different species of bacteria, the interaction of bacteria with their environment, and methods used to obtain experimentally verified parameter values. We allude briefly to the role of modeling pattern formation in understanding collective behavior within bacterial populations. Various aspects of each model are discussed and areas for possible future research are postulated

Liberalizing trade in environmental goods and services

We examine the effects of trade liberalization in environmental goods in a model with one domestic downstream polluting firm and two upstream firms (one domestic, one foreign). The upstream firms offer their technologies to the downstream firm at a flat fee. The domestic government sets the emission tax rate after the outcome of R&D is known. The effect of liberalization on the domestic upstream firm's R&D incentive is ambiguous. Liberalization usually results in cleaner production, which allows the country to reach higher welfare. However this increase in welfare is typically achieved at the expense of the environment (a backfire effect)

Haloarchaea swim slowly for optimal chemotactic efficiency in low nutrient environments

Archaea have evolved to survive in some of the most extreme environments on earth. Life in extreme, nutrient-poor conditions gives the opportunity to probe fundamental energy limitations on movement and response to stimuli, two essential markers of living systems. Here we use three-dimensional holographic microscopy and computer simulations to reveal that halophilic archaea achieve chemotaxis with power requirements one hundred-fold lower than common eubacterial model systems. Their swimming direction is stabilised by their flagella (archaella), enhancing directional persistence in a manner similar to that displayed by eubacteria, albeit with a different motility apparatus. Our experiments and simulations reveal that the cells are capable of slow but deterministic chemotaxis up a chemical gradient, in a biased random walk at the thermodynamic limit

First inverse kinematics study of the Ne 22 (p,γ) Na 23 reaction and its role in AGB star and classical nova nucleosynthesis

Background: Globular clusters are known to exhibit anomalous abundance trends such as the sodium-oxygen anticorrelation. This trend is thought to arise via pollution of the cluster interstellar medium from a previous generation of stars. Intermediate-mass asymptotic giant branch stars undergoing hot bottom burning (HBB) are a prime candidate for producing sodium-rich oxygen-poor material, and then expelling this material via strong stellar winds. The amount of Na23 produced in this environment has been shown to be sensitive to uncertainties in the Ne22(p,γ)Na23 reaction rate. The Ne22(p,γ)Na23 reaction is also activated in classical nova nucleosynthesis, strongly influencing predicted isotopic abundance ratios in the Na-Al region. Therefore, improved nuclear physics uncertainties for this reaction rate are of critical importance for the identification and classification of pre-solar grains produced by classical novae. Purpose: At temperatures relevant for both HBB in AGB stars and classical nova nucleosynthesis, the Ne22(p,γ)Na23 reaction rate is dominated by narrow resonances, with additional contribution from direct capture. This study presents new strength values for seven resonances, as well as a study of direct capture. Method: The experiment was performed in inverse kinematics by impinging an intense isotopically pure beam of Ne22 onto a windowless H2 gas target. The Na23 recoils and prompt γ rays were detected in coincidence using a recoil mass separator coupled to a 4π bismuth-germanate scintillator array surrounding the target. Results: For the low-energy resonances, located at center of mass energies of 149, 181, and 248 keV, we recover stength values of ωγ149=0.17-0.04+0.05, ωγ181=2.2±0.4, and ωγ248=8.2±0.7 μeV, respectively. These results are in broad agreement with recent studies performed by the LUNA and TUNL groups. However, for the important reference resonance at 458 keV we obtain a strength value of ωγ458=0.44±0.02 eV, which is significantly lower than recently reported values. This is the first time that this resonance has been studied completely independently from other resonance strengths. For the 632-keV resonance we recover a strength value of ωγ632=0.48±0.02 eV, which is an order of magnitude higher than a recent study. For reference resonances at 610- A nd 1222-keV, our strength values are in agreement with the literature. In the case of direct capture, we recover an S factor of 60 keV b, consistent with prior forward kinematics experiments. Conclusions: In summary, we have performed the first direct measurement of Ne22(p,γ)Na23 in inverse kinematics. Our results are in broad agreement with the literature, with the notable exception of the 458-keV resonance, for which we obtain a lower strength value. We assessed the impact of the present reaction rate in reference to a variety of astrophysical environments, including AGB stars and classical novae. Production of Na23 in AGB stars is minimally influenced by the factor of 4 increase in the present rate compared to the STARLIB-2013 compilation. The present rate does however impact upon the production of nuclei in the Ne-Al region for classical novae, with dramatically improved uncertainties in the predicted isotopic abundances present in the novae ejecta

There and back again: historical perspective and future directions for Vaccinium breeding and research studies

The genus Vaccinium L. (Ericaceae) contains a wide diversity of culturally and economically important berry crop species. Consumer demand and scientific research in blueberry (Vaccinium spp.) and cranberry (Vaccinium macrocarpon) have increased worldwide over the crops' relatively short domestication history (~100&nbsp;years). Other species, including bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), and ohelo berry (Vaccinium reticulatum) are largely still harvested from the wild but with crop improvement efforts underway. Here, we present a review article on these Vaccinium berry crops on topics that span taxonomy to genetics and genomics to breeding. We highlight the accomplishments made thus far for each of these crops, along their journey from the wild, and propose research areas and questions that will require investments by the community over the coming decades to guide future crop improvement efforts. New tools and resources are needed to underpin the development of superior cultivars that are not only more resilient to various environmental stresses and higher yielding, but also produce fruit that continue to meet a variety of consumer preferences, including fruit quality and health related trait

Cell morphology governs directional control in swimming bacteria

The ability to rapidly detect and track nutrient gradients is key to the ecological success of motile bacteria in aquatic systems. Consequently, bacteria have evolved a number of chemotactic strategies that consist of sequences of straight runs and reorientations. Theoretically, both phases are affected by fluid drag and Brownian motion, which are themselves governed by cell geometry. Here, we experimentally explore the effect of cell length on control of swimming direction. We subjected Escherichia coli to an antibiotic to obtain motile cells of different lengths, and characterized their swimming patterns in a homogeneous medium. As cells elongated, angles between runs became smaller, forcing a change from a run-and-tumble to a run-and-stop/reverse pattern. Our results show that changes in the motility pattern of microorganisms can be induced by simple morphological variation, and raise the possibility that changes in swimming pattern may be triggered by both morphological plasticity and selection on morphology