The Social Wasps (Hymenoptera: Vespidae) of Indiana

An updated taxonomic treatment of the social wasps (Hymenoptera: Vespidae) of Indiana is made. Illustrated identification keys are provided for species of Polistes, Vespa, Vespula, and Dolichovespula. New distributional records and biological notes are provided for each species

Predicting adaptive responses - simulating occupied environments

Simulation of building performance is increasingly being used in design practice to predict comfort of occupants in finished buildings. This is an area of great uncertainty: what actions does a person take when too warm or suffering from glare; how is comfort measured; how do groups of people interact to control environmental conditions, etc? An increasing attention to model these issues is evident in current research. Two issues are covered in this paper: how comfort can be assessed and what actions occupants are likely to make to achieve and maintain a comfortable status. The former issue describes the implementation of existing codes within a computational framework. This is non-trivial as information on local air velocities, radiant temperature and air temperature and relative humidity have to be predicted as they evolve over time in response to changing environmental conditions. This paper also presents a nascent algorithm for modelling occupant behaviour with respect to operable windows. The algorithm is based on results of several field studies which show the influence of internal and external temperatures on decision making in this respect. The derivation and implementation of the algorithm is discussed, highlighting areas where further effort could be of benefit

Applying inspection to object-oriented software

The benefits of the object-oriented paradigmare widely cited. At the same time, inspection is deemed to be the most cost-effective means of detecting defects in software products. Why then, is there no published experience, let alone quantitative data, on the application of inspection to object-oriented systems? We describe the facilities of the object-oriented paradigm and the issues that these raise when inspecting object-oriented code. Several problems are caused by the disparity between the static code structure and its dynamic runtime behaviour. The large number of small methods in object-oriented systems can also cause problems. We then go on to describe three areas which may help mitigate problems found. Firstly, the use of various programming methods may assist in making object-oriented code easier to inspect. Secondly, improved program documentation can help the inspector understand the code which is under inspection. Finally, tool support can help the inspector to analyse the dynamic behaviour of the code. We conclude that while both the object-oriented paradigm and inspection provide excellent benefits on their own, combining the two may be a difficult exercise, requiring extensive support if it is to be successful

At What Rate Do Farmers Substitute Manure For Commercial Fertilizers?

Water quality has implications for the health of our ecosystem and the welfare of our population. Agriculture is one of the major contributors of non-point source pollution that contaminates our nation's water supplies. Understanding how farmers substitute manure for commercial fertilizers allows us to better understand the level of nitrogen that enters the soil and can seep into our waterways. In this paper, we explore the factors that help determine farmers' substitution rates between the two types of fertilizers. Location, crop type, and time all could play important roles. We analyze USDA farm level survey data for both crop and livestock farms covering the years 1996 to 2002 to create substitution rate estimates used on corn, soybean, and wheat fields. While the substitution rates we found did not appear to change over the time frame examined, we did find that crop type and location significantly affected the rates that farmers use. Additionally, and perhaps most importantly, the substitution rates we did find did not conform to the "perfect substitution" between N coming from commercial sources and manure used in much of the literature. This means that previous studies could have underestimated the potential level of pollution of our water by our nations' farms.Farm Management,

Spin-dependent Seebeck coefficients of Ni_{80}Fe_{20} and Co in nanopillar spin valves

We have experimentally determined the spin-dependent Seebeck coefficient of permalloy (Ni_{80}Fe_{20}) and cobalt (Co) using nanopillar spin valve devices. The devices were specifically designed to completely separate heat related effects from charge related effects. A pure heat current through the nanopillar spin valve, a stack of two ferromagnetic layers (F) separated by a non-magnetic layer (N), leads to a thermovoltage proportional to the spin-dependent Seebeck coefficient S_{S}=S_{\uparrow}-S_{\downarrow} of the ferromagnet, where S_{\uparrow} and S_{\downarrow} are the Seebeck coefficient for spin-up and spin-down electrons. By using a three-dimensional finite-element model (3D-FEM) based on spin-dependent thermoelectric theory, whose input material parameters were measured in separate devices, we were able to accurately determine a spin-dependent Seebeck coefficient of -1.8 microvolt/Kelvin and -4.5 microvolt/Kelvin for cobalt and permalloy, respectively corresponding to a Seebeck coefficient polarization P_{S}=S_{S}/S_{F} of 0.08 and 0.25, where S_{F} is the Seebeck coefficient of the ferromagnet. The results are in agreement with earlier theoretical work in Co/Cu multilayers and spin-dependent Seebeck and spin-dependent Peltier measurements in Ni_{80}Fe_{20}/Cu spin valve structures

Effect of Edge Roughness on Electronic Transport in Graphene Nanoribbon Channel Metal Oxide Semiconductor Field-Effect Transistors

Results of quantum mechanical simulations of the influence of edge disorder on transport in graphene nanoribbon metal oxide semiconductor field-effect transistors (MOSFETs) are reported. The addition of edge disorder significantly reduces ON-state currents and increases OFF-state currents, and introduces wide variability across devices. These effects decrease as ribbon widths increase and as edges become smoother. However the bandgap decreases with increasing width, thereby increasing the band-to-band tunneling mediated subthreshold leakage current even with perfect nanoribbons. These results suggest that without atomically precise edge control during fabrication, MOSFET performance gains through use of graphene will be difficult to achieve.Comment: 8 pages, 5 figure

Collective excitations in double-layer quantum Hall systems

We study the collective excitation spectra of double-layer quantum-Hall systems using the single mode approximation. The double-layer in-phase density excitations are similar to those of a single-layer system. For out-of-phase density excitations, however, both inter-Landau-level and intra-Landau-level double-layer modes have finite dipole oscillator strengths. The oscillator strengths at long wavelengths for the latter transitions are shifted upward by interactions by identical amounts proportional to the interlayer Coulomb coupling. The intra-Landau-level out-of-phase mode has a gap when the ground state is incompressible except in the presence of spontaneous inter-layer coherence. We compare our results with predictions based on the Chern-Simons-Landau-Ginzburg theory for double-layer quantum Hall systems.Comment: RevTeX, 21 page

EPR and ferromagnetism in diluted magnetic semiconductor quantum wells

Motivated by recent measurements of electron paramagnetic resonance (EPR) spectra in modulation-doped CdMnTe quantum wells, [F.J. Teran {\it et al.}, Phys. Rev. Lett. {\bf 91}, 077201 (2003)], we develop a theory of collective spin excitations in quasi-two-dimensional diluted magnetic semiconductors (DMSs). Our theory explains the anomalously large Knight shift found in these experiments as a consequence of collective coupling between Mn-ion local moments and itinerant-electron spins. We use this theory to discuss the physics of ferromagnetism in (II,Mn)VI quantum wells, and to speculate on the temperature at which it is likely to be observed in n-type modulation doped systems.Comment: 4 pages, 1 figur

A generalized Macdonald operator

We present an explicit difference operator diagonalized by the Macdonald polynomials associated with an (arbitrary) admissible pair of irreducible reduced crystallographic root systems. By the duality symmetry, this gives rise to an explicit Pieri formula for the Macdonald polynomials in question. The simplest examples of our construction recover Macdonald's celebrated difference operators and associated Pieri formulas pertaining to the minuscule and quasi-minuscule weights. As further by-products, explicit expansions and Littlewood-Richardson type formulas are obtained for the Macdonald polynomials associated with a special class of small weights.Comment: 11 pages. To appear in Int. Math. Res. Not. IMR