Abundance, growth, and predation by non-native brown trout in the Trinity River, CA

Brown Trout were introduced to the Trinity River in Northern California in the 1890’s. Since 1932, Brown Trout have sustained their population without additional stocking. Over the last 15 years, fisheries managers have been concerned that predation by piscivorous Brown Trout may impede efforts to restore native salmonids, in particular endangered Coho Salmon. I investigated predation by Brown Trout on native fish in the 64 km of the main stem Trinity River below Lewiston Dam. Using a bioenergetics approach parameterized with field measurements of Brown Trout abundance and growth, I estimated the amount of energy needed to sustain the 2015 Brown Trout population and used stable isotope analysis and gastric lavage to quantify the biomass of prey consumed over the course of a single year. I found that Brown Trout, particularly large individuals, primarily ate hatchery fish. Invertebrates were the next most popular prey followed by wild salmonids and ammocoetes. I estimated that in 2015, Brown Trout ate 6.5% of the biomass released from Trinity Hatchery (95% CI 4.1 to 9.6 %) and the wild consumption was equivalent to 23% (95% CI 1.4 to 88%) of the biomass of wild salmonids which survived to emigrate out of the study reach

ValueMapper: an interactive web-based tool to map and visualise spatial data

ValueMapper is a flexible and easy-to-use web-based application for mapping, visualising, and storing spatial information. The tool was developed to support mapping areas of conservation, cultural or economic interest, a.k.a. place or landscape values, but can be used for other purposes. The tool allows mapping, modifying, describing, and saving polygons in ESRI Shapefile format, which can be visualised using the tool or further edited using GIS software. The web-based interface allows users to draw and save polygons with information about the features (areas) of interest. For example, documenting their name, category, description, accuracy, sensitivity, custodians, and other relevant characteristics of the mapped features of interest. The software facilitates participatory mapping of landscape values to support environmental planning and management, including conservation and land/ water use planning initiatives. James Cook University developed the tool to support a project on multi-objective planning in northern Australia. The tool was developed and tested during a research project guiding participatory scenario planning to explore alternative development pathways for the Fitzroy River catchment of the Kimberley, Western Australia. Depending on the mapping and planning exercise's goals, context, and resources, more advanced and custom-made tools may be required. The software can be combined with other tools (e.g. interactive tabletop projectors, 3D models), facilitating knowledge sharing and co-production

Tunneling between fermionic vacua and the overlap formalism

The probability amplitude for tunneling between the Dirac vacua corresponding to different signs of a parity breaking fermionic mass $M$ in $2+1$ dimensions is studied, making contact with the continuum overlap formulation for chiral determinants. It is shown that the transition probability in the limit when $M \to \infty$ corresponds, via the overlap formalism, to the squared modulus of a chiral determinant in two Euclidean dimensions. The transition probabilities corresponding to two particular examples: fermions on a torus with twisted boundary conditions, and fermions on a disk in the presence of an external constant magnetic field are evaluated.Comment: Reference added. 12 pages, LateX, no figure

Targeting of mesenchymal stem cells to ovarian tumors via an artificial receptor

<p>Abstract</p> <p>Background</p> <p>Mesenchymal Progenitor/Stem Cells (MSC) respond to homing cues providing an important mechanism to deliver therapeutics to sites of injury and tumors. This property has been confirmed by many investigators, however, the efficiency of tumor homing needs to be improved for effective therapeutic delivery. We investigated the feasibility of enhancing MSC tumor targeting by expressing an artificial tumor-binding receptor on the MSC surface.</p> <p>Methods</p> <p>Human MSC expressing an artificial receptor that binds to erbB2, a tumor cell marker, were obtained by transduction with genetically modified adenoviral vectors encoding an artificial receptor (MSC-AR). MSC-AR properties were tested <it>in vitro </it>in cell binding assays and <it>in vivo </it>using two model systems: transient transgenic mice that express human erbB2 in the lungs and ovarian xenograft tumor model. The levels of luciferase-labeled MSCs in erbB2-expressing targeted sites were evaluated by measuring luciferase activity using luciferase assay and imaging.</p> <p>Results</p> <p>The expression of AR enhanced binding of MSC-AR to erbB2-expressing cells <it>in vitro</it>, compared to unmodified MSCs. Furthermore, we have tested the properties of erbB2-targeted MSCs <it>in vivo </it>and demonstrated an increased retention of MSC-AR in lungs expressing erbB2. We have also confirmed increased numbers of erbB2-targeted MSCs in ovarian tumors, compared to unmodified MSC. The kinetic of tumor targeting by ip injected MSC was also investigated.</p> <p>Conclusion</p> <p>These data demonstrate that targeting abilities of MSCs can be enhanced via introduction of artificial receptors. The application of this strategy for tumor cell-based delivery could increase a number of cell carriers in tumors and enhance efficacy of cell-based therapy.</p

Exact Beta Functions in the Vector Model and Renormalization Group Approach

The validity of the renormalization group approach for large $N$ is clarified by using the vector model as an example. An exact difference equation is obtained which relates free energies for neighboring values of $N$. The reparametrization freedom in field space provides infinitely many identities which reduce the infinite dimensional coupling constant space to that of finite dimensions. The effective beta functions give exact values for the fixed points and the susceptibility exponents.Comment: 13 pages (no figures) in LaTeX, TIT/HEP-215, NUP-A-93-4, a few minor correction

Renormalizable 1/N_f Expansion for Field Theories in Extra Dimensions

We demonstrate how one can construct renormalizable perturbative expansion in formally nonrenormalizable higher dimensional field theories. It is based on $1/N_f$-expansion and results in a logarithmically divergent perturbation theory in arbitrary high space-time dimension. First, we consider a simple example of $N$-component scalar filed theory and then extend this approach to Abelian and non-Abelian gauge theories with $N_f$ fermions. In the latter case, due to self-interaction of non-Abelian fields the proposed recipe requires some modification which, however, does not change the main results. The resulting effective coupling is dimensionless and is running in accordance with the usual RG equations. The corresponding beta function is calculated in the leading order and is nonpolynomial in effective coupling. It exhibits either UV asymptotically free or IR free behaviour depending on the dimension of space-time. The original dimensionful coupling plays a role of a mass and is also logarithmically renormalized. We analyze also the analytical properties of a resulting theory and demonstrate that in general it acquires several ghost states with negative and/or complex masses. In the former case, the ghost state can be removed by a proper choice of the coupling. As for the states with complex conjugated masses, their contribution to physical amplitudes cancels so that the theory appears to be unitary.Comment: 32 pages, 20 figure

Calculation of the Characteristic Functions of Anharmonic Oscillators

The energy levels of quantum systems are determined by quantization conditions. For one-dimensional anharmonic oscillators, one can transform the Schrodinger equation into a Riccati form, i.e., in terms of the logarithmic derivative of the wave function. A perturbative expansion of the logarithmic derivative of the wave function can easily be obtained. The Bohr-Sommerfeld quantization condition can be expressed in terms of a contour integral around the poles of the logarithmic derivative. Its functional form is B_m(E,g) = n + 1/2, where B is a characteristic function of the anharmonic oscillator of degree m, E is the resonance energy, and g is the coupling constant. A recursive scheme can be devised which facilitates the evaluation of higher-order Wentzel-Kramers-Brioullin (WKB) approximants. The WKB expansion of the logarithmic derivative of the wave function has a cut in the tunneling region. The contour integral about the tunneling region yields the instanton action plus corrections, summarized in a second characteristic function A_m(E,g). The evaluation of A_m(E,g) by the method of asymptotic matching is discussed for the case of the cubic oscillator of degree m=3.Comment: 11 pages, LaTeX; three further typographical errors correcte

Van Der Waals Heterostructure Engineered Quantum Anomalous Hall Effect

The quantum anomalous hall effect (QAHE) is a phase of matter in which a dissipationless current is made to flow around the edge of a two dimensional (2D) material. Making use of this effect for next generation electronics could lead to faster processors and low power devices. There are very few materials that exist in nature that intrinsically possess the QAHE, however by sandwiching target 2D materials together we can establish this highly sought after phase. By using three 2D materials: graphene, molybdenum disulfide (MoS2) and chromium tri-iodide (CrI3) forming a van der Waals heterostructure we can create a proximity induced magnetism effect. Here, we took highly sensitive capacitance measurements of graphene on MoS2 devices at low temperatures and high magnetic fields. By taking measurements of the penetration field capacitance vs charge density and polarization of a graphene and MoS2 device at 2 Kelvin and zero external magnetic field, we are able to see the charge neutrality point in graphene and the conduction band of MoS2. Using this method of capacitance measurements we plan to integrate thin CrI3 flakes into our graphene and MoS2 devices to develop a full device to study the proximity induced QAHE.https://digitalscholarship.unlv.edu/durep_podium/1019/thumbnail.jp

On the Electric Charge of Monopoles at Finite Temperature

We calculate the electric charge at finite temperature $T$ for non-Abelian monopoles in spontaneously broken gauge theories with a CP violating $\theta$-term. A careful treatment of dyon's gauge degrees of freedom shows that Witten formula for the dyon charge at $T=0$, $Q = e(n - \theta/2\pi)$, remains valid at $T \ne 0$.Comment: 13 pages, latex file, no figure