Long-term population fluctuations of small mammals at the UWM Field Station

Population sizes of four small mammals, Peromyscus leucopus, Microtus pennsylvanicus, Blarina brevicauda, and Sorex cinereus, were monitored for over twenty years at the UWM Field Station. P. leucopus had moderate fluctuations in size, but showed no evidence of cyclic or regular fluctuations. M. pennsylvanicus exhibited dramatic fluctuations with cycles of 3-5 years. Neither shrew species appeared to have cyclic fluctuations. The population sizes of the two shrew species were positively correlated with each other. No other significant correlations were found between species. Population sizes were probably influenced by a number of factors including predation, competition and weather

Maintaining a way of life: trials and tribulations of farmers’ market families

Never before in our nation’s history has there been so many ways for consumers to purchase food. From grocery stores, to super centers such as Wal-Mart and Costco, convenience stores, online purchases, community supported agriculture (CSA), and farmers’ markets, Americans have a multitude of venues to choose from. Although many Americans currently purchase their foods from grocery stores, a growing number of them are buying locally at their farmers’ markets and from CSAs. As the sustainability movement takes a greater foothold in the American household, local products and local foods are becoming ever more important and prevalent. Yet with all of the statistics surrounding local agriculture, the human element is often lost. A majority of small farmers and their spouses, often the ones who sell at a local level, have to work full time both on and off farm to support their families and farms. This case study examines the professional lives of five local farm families who choose to sell their products at the Fayetteville, Arkansas farmers’ market. It seeks to understand farmers’ reasons for farming and selling locally, as well as their biggest challenges and rewards. In addition, it seeks to fill gaps in literature regarding farmers’ motivations for selling at a local level

Cellular Communication through Light

Information transfer is a fundamental of life. A few studies have reported that cells use photons (from an endogenous source) as information carriers. This study finds that cells can have an influence on other cells even when separated with a glass barrier, thereby disabling molecule diffusion through the cell-containing medium. As there is still very little known about the potential of photons for intercellular communication this study is designed to test for non-molecule-based triggering of two fundamental properties of life: cell division and energy uptake. The study was performed with a cellular organism, the ciliate Paramecium caudatum. Mutual exposure of cell populations occurred under conditions of darkness and separation with cuvettes (vials) allowing photon but not molecule transfer. The cell populations were separated either with glass allowing photon transmission from 340 nm to longer waves, or quartz being transmittable from 150 nm, i.e. from UV-light to longer waves. Even through glass, the cells affected cell division and energy uptake in neighboring cell populations. Depending on the cuvette material and the number of cells involved, these effects were positive or negative. Also, while paired populations with lower growth rates grew uncorrelated, growth of the better growing populations was correlated. As there were significant differences when separating the populations with glass or quartz, it is suggested that the cell populations use two (or more) frequencies for cellular information transfer, which influences at least energy uptake, cell division rate and growth correlation. Altogether the study strongly supports a cellular communication system, which is different from a molecule-receptor-based system and hints that photon-triggering is a fine tuning principle in cell chemistry

Factors Influencing the Green House Gas Footprint of US Dairy Farms

Environmental Economics and Policy, Livestock Production/Industries,

Economic and Conservation Evaluation of Capital Renovation Projects: Hidalgo County Irrigation District No. 1 (Edinburg) - North Branch / East Main - Final

Initial construction costs and net annual changes in operating and maintenance expenses are identified for a single-component capital renovation project proposed by Hidalgo County Irrigation District No. 1 to the Bureau of Reclamation and North American Development Bank. The proposed project involves installing 4.83 miles of multi-size pipeline to replace a segment of the North Branch / East Main canal. Both nominal and real estimates of water and energy savings and expected economic and financial costs of those savings are identified throughout the anticipated 48-year useful life for the proposed project. Sensitivity results for both the cost of water savings and cost of energy savings are presented for several important parameters. Annual water and energy savings forthcoming from the total project are estimated, using amortization procedures, to be 5,838 ac-ft of water per year and 3,293,049,926 BTUs (965,138 kwh) of energy per year. The calculated economic and financial cost of water savings is estimated to be $15.58 per ac-ft. The calculated economic and financial cost of energy savings is estimated at$0.0000392 per BTU ($0.134 per kwh). In addition, expected real (rather than nominal) values are indicated for the Bureau of Reclamation’s three principal evaluation measures specified in the United States Public Law 106-576 legislation. The initial construction cost per ac-ft of water savings measure is$30.68 per ac-ft of water savings. The initial construction cost per BTU (kwh) of energy savings measure is $0.0000544 per BTU ($0.186 per kwh). The ratio of initial construction costs per dollar of total annual economic savings is estimated to be -1.58

Detection and construction of an elliptic solution to the complex cubic-quintic Ginzburg-Landau equation

In evolution equations for a complex amplitude, the phase obeys a much more intricate equation than the amplitude. Nevertheless, general methods should be applicable to both variables. On the example of the traveling wave reduction of the complex cubic-quintic Ginzburg-Landau equation (CGL5), we explain how to overcome the difficulties arising in two such methods: (i) the criterium that the sum of residues of an elliptic solution should be zero, (ii) the construction of a first order differential equation admitting the given equation as a differential consequence (subequation method).Comment: 12 pages, no figure, to appear, Theoretical and Mathematical Physic

Interferometry with Bose-Einstein Condensates in Microgravity

Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Due to their unique coherence properties, Bose-Einstein condensates are ideal sources for an atom interferometer in extended free fall. In this paper we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far-field of a double-slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.Comment: 8 pages, 3 figures; 8 pages of supporting materia

A simulation study of the reaction of human heart to biphasic electrical shocks

BACKGROUND: This article presents a study, which examines the effects of biphasic electrical shocks on human ventricular tissue. The effects of this type of shock are not yet fully understood. Animal experiments showed the superiority of biphasic shocks over monophasic ones in defibrillation. A mathematical computer simulation can increase the knowledge of human heart behavior. METHODS: The research presented in this article was done with different models representing a three-dimensional wedge of ventricular myocardium. The electrophysiology was described with Priebe-Beuckelmann model. The realistic fiber twist, which is specific to human myocardium was included. Planar electrodes were placed at the ends of the longest side of the virtual cardiac wedge, in a bath medium. They were sources of electrical shocks, which varied in magnitude from 0.1 to 5 V. In a second arrangement ring electrodes were placed directly on myocardium for getting a better view on secondary electrical sources. The electrical reaction of the tissue was generated with a bidomain model. RESULTS: The reaction of the tissue to the electrical shock was specific to the initial imposed characteristics. Depolarization appeared in the first 5 ms in different locations. A further study of the cardiac tissue behavior revealed, which features influence the response of the considered muscle. It was shown that the time needed by the tissue to be totally depolarized is much shorter when a biphasic shock is applied. Each simulation ended only after complete repolarization was achieved. This created the possibility of gathering information from all states corresponding to one cycle of the cardiac rhythm. CONCLUSIONS: The differences between the reaction of the homogeneous tissue and a tissue, which contains cleavage planes, reveals important aspects of superiority of biphasic pulses. ..

Phase chaos in the anisotropic complex Ginzburg-Landau Equation

Of the various interesting solutions found in the two-dimensional complex Ginzburg-Landau equation for anisotropic systems, the phase-chaotic states show particularly novel features. They exist in a broader parameter range than in the isotropic case, and often even broader than in one dimension. They typically represent the global attractor of the system. There exist two variants of phase chaos: a quasi-one dimensional and a two-dimensional solution. The transition to defect chaos is of intermittent type.Comment: 4 pages RevTeX, 5 figures, little changes in figures and references, typos removed, accepted as Rapid Commun. in Phys. Rev.