Connecting Undergraduate Students as Partners in Computer Science Teaching and Research

Connecting undergraduate students as partners can lead to the enhancement of the undergraduate experience and allow students to see the different sides of the university. Such holistic perspectives may better inform academic career choices and postgraduate study. Furthermore, student involvement in course development has many potential benefits. This paper outlines a framework for connecting research and teaching within Computer Science- though this is applicable across other disciplines. Three case studies are considered to illustrate the approach. The first case study involves students in their honours’ stage (level 6, typically 3rd year) project, the second an undergraduate intern between stages 5 and 6, and finally, a MSc (level 7) project. All three case studies have actively involved students in core parts of the University’s teaching and research activities, producing usable software systems to support these efforts. We consider this as a continuing engagement process to enhance the undergraduate learning experience within Computer Science

The Storm-Track Response to Idealized SST Perturbations in an Aquaplanet GCM

The tropospheric response to midlatitude SST anomalies has been investigated through a series of aquaplanet simulations using a high-resolution version of the Hadley Centre atmosphere model (HadAM3) under perpetual equinox conditions. Model integrations show that increases in the midlatitude SST gradient generally lead to stronger storm tracks that are shifted slightly poleward, consistent with changes in the lower-tropospheric baroclinicity. The large-scale atmospheric response is, however, highly sensitive to the position of the SST gradient anomaly relative to that of the subtropical jet in the unperturbed atmosphere. In particular, when SST gradients are increased very close to the subtropical jet, then the Hadley cell and subtropical jet is strengthened while the storm track and eddy-driven jet are shifted equatorward. Conversely, if the subtropical SST gradients are reduced and the midlatitude gradients increased, then the storm track shows a strong poleward shift and a well-separated eddy-driven jet is produced. The sign of the SST anomaly is shown to play a secondary role in determining the overall tropospheric response. These findings are used to provide a new and consistent interpretation of some previous GCM studies concerning the atmospheric response to midlatitude SST anomalies

Evaluating Multiple Arthropod Taxa as Indicators of Invertebrate Diversity in Old Fields

Biodiversity, often quantified by species richness, is commonly used to evaluate and monitor the health of ecosystems and as a tool for conservation planning. The use of one or more focal taxa as surrogates or indicators of larger taxonomic diversity can greatly expedite the process of biodiversity measurement. This is especially true when studying diverse and abundant invertebrate fauna. Before indicator taxa are employed, however, research into their suitability as indicators of greater taxonomic diversity in an area is needed. We sampled invertebrate diversity in old fields in southern Michigan using pitfall trapping and morphospecies designations after identification to order or family. Correlation analysis was used to assess species richness relationships between focal arthropod taxa and general invertebrate diversity. Relationships were assessed at two fine spatial scales: within sampling patches, and locally across four sampling patches. Cumulative richness of all assessed taxa increased proportionately with cumulative invertebrate richness as sampling intensity increased within patches. At the among-patch scale, we tentatively identified Hemiptera and Coleoptera as effective indicator taxa of greater invertebrate richness. Although Hymenoptera, Araneae and Diptera exhibited high species richness, their total richness within patches was not associated with overall invertebrate richness among patches. Increased sampling throughout the active season and across a greater number of habitat patches should be conducted before adopting Hemiptera and Coleoptera as definitive indicators of general invertebrate richness in the Great Lakes region. Multiple sampling techniques, in addition to pitfall trapping, should also be added to overcome capture biases associated with each technique

The basic ingredients of the North Atlantic storm track. Part I: land-sea contrast and orography

Understanding and predicting changes in storm tracks over longer time scales is a challenging problem, particularly in the North Atlantic. This is due in part to the complex range of forcings (land–sea contrast, orography, sea surface temperatures, etc.) that combine to produce the structure of the storm track. The impact of land–sea contrast and midlatitude orography on the North Atlantic storm track is investigated through a hierarchy of GCM simulations using idealized and “semirealistic” boundary conditions in a high-resolution version of the Hadley Centre atmosphere model (HadAM3). This framework captures the large-scale essence of features such as the North and South American continents, Eurasia, and the Rocky Mountains, enabling the results to be applied more directly to realistic modeling situations than was possible with previous idealized studies. The physical processes by which the forcing mechanisms impact the large-scale flow and the midlatitude storm tracks are discussed. The characteristics of the North American continent are found to be very important in generating the structure of the North Atlantic storm track. In particular, the southwest–northeast tilt in the upper tropospheric jet produced by southward deflection of the westerly flow incident on the Rocky Mountains leads to enhanced storm development along an axis close to that of the continent’s eastern coastline. The approximately triangular shape of North America also enables a cold pool of air to develop in the northeast, intensifying the surface temperature contrast across the eastern coastline, consistent with further enhancements of baroclinicity and storm growth along the same axis

Effective theories of scattering with an attractive inverse-square potential and the three-body problem

A distorted-wave version of the renormalisation group is applied to scattering by an inverse-square potential and to three-body systems. In attractive three-body systems, the short-distance wave function satisfies a Schroedinger equation with an attractive inverse-square potential, as shown by Efimov. The resulting oscillatory behaviour controls the renormalisation of the three-body interactions, with the renormalisation-group flow tending to a limit cycle as the cut-off is lowered. The approach used here leads to single-valued potentials with discontinuities as the bound states are cut off. The perturbations around the cycle start with a marginal term whose effect is simply to change the phase of the short-distance oscillations, or the self-adjoint extension of the singular Hamiltonian. The full power counting in terms of the energy and two-body scattering length is constructed for short-range three-body forces.Comment: 19 pages (RevTeX), 2 figure

Force chains as the link between particle and bulk friction angles in granular material

From sediment transport in rivers to landslides, predictions of granular motion rely on a Mohr-Coulomb failure criterion parameterized by a friction angle. Measured friction angles are generally large for single grains, smaller for large numbers of grains, and no theory exists for intermediate numbers of grains. We propose that a continuum of friction angles exists between single-grain and bulk friction angles due to grain-to-grain force chains. Physical experiments, probabilistic modeling, and discrete element modeling demonstrate that friction angles decrease by up to 15° as the number of potentially mobile grains increases from 1 to ~20. Decreased stability occurs as longer force chains more effectively dislodge downslope “keystone” grains, implying that bulk friction angles are set by the statistics of single-grain friction angles. Both angles are distinct from and generally larger than grain contact-point friction, with implications for a variety of sediment transport processes involving small clusters of grains

Solid-state interconversions: Unique 100% reversible transformations between the ground and metastable states in single-crystals of a series of nickel( II) nitro complexes

The solid-state, low-temperature linkage isomerism in a series of five square planar group 10 phosphino nitro complexes have been investigated by a combination of photocrystallographic experiments, Raman spectroscopy and computer modelling. The factors influencing the reversible solid-state interconversion between the nitro and nitrito structural isomers have also been investigated, providing insight into the dynamics of this process. The cis-[Ni(dcpe)(NO2)2] (1) and cis-[Ni(dppe)(NO2)2] (2) complexes show reversible 100 % interconversion between the η1-NO2 nitro isomer and the η1-ONO nitrito form when single-crystals are irradiated with 400 nm light at 100 K. Variable temperature photocrystallographic studies for these complexes established that the metastable nitrito isomer reverted to the ground-state nitro isomer at temperatures above 180 K. By comparison, the related trans complex [Ni(PCy3)2(NO2)2] (3) showed 82 % conversion under the same experimental conditions at 100 K. The level of conversion to the metastable nitrito isomers is further reduced when the nickel centre is replaced by palladium or platinum. Prolonged irradiation of the trans-[Pd(PCy3)2(NO2)2] (4) and trans-[Pt(PCy3)2(NO2)2] (5) with 400 nm light gives reversible conversions of 44 and 27 %, respectively, consistent with the slower kinetics associated with the heavier members of group 10. The mechanism of the interconversion has been investigated by theoretical calculations based on the model complex [Ni(dmpe)Cl(NO2)]

Stable carbon Isotope evidence for neolithic and bronze age crop water management in the eastern mediterranean and southwest asia

In a large study on early crop water management, stable carbon isotope discrimination was determined for 275 charred grain samples from nine archaeological sites, dating primarily to the Neolithic and Bronze Age, from the Eastern Mediterranean and Western Asia. This has revealed that wheat (Triticum spp.) was regularly grown in wetter conditions than barley (Hordeum sp.), indicating systematic preferential treatment of wheat that may reflect a cultural preference for wheat over barley. Isotopic analysis of pulse crops (Lens culinaris, Pisum sativum and Vicia ervilia) indicates cultivation in highly varied water conditions at some sites, possibly as a result of opportunistic watering practices. The results have also provided evidence for local land-use and changing agricultural practices