A Challenge to All: Raising the Participation and Success of Women and Minorities in Mathematics, Science, and Technlogy

This issue of our journal is the product of a Virginia Mathematics and Science Coalition (VMSC) conference titled, Programs That Work and held in March, 2000 on the issues of raising both the levels of success and the levels of participation of women and minorities in mathematics, science, and technology. Traditionally, these two groups have had low rates of participation in these subjects, and we believe this situation can and must be changed. The conference was to Coalition\u27s first direct assault on the problem

Large-scale atomistic density functional theory calculations of phosphorus-doped silicon quantum bits

We present density functional theory calculations of phosphorus dopants in bulk silicon and of several properties relating to their use as spin qubits for quantum computation. Rather than a mixed pseudopotential or a Heitler-London approach, we have used an explicit treatment for the phosphorus donor and examined the detailed electronic structure of the system as a function of the isotropic doping fraction, including lattice relaxation due to the presence of the impurity. Doping electron densities and spin densities are examined in order to study the properties of the dopant electron as a function of the isotropic doping fraction. Doping potentials are also calculated for use in calculations of the scattering cross-sections of the phosphorus dopants, which are important in the understanding of electrically detected magnetic resonance experiments. We find that the electron density around the dopant leads to non-spherical features in the doping potentials, such as trigonal lobes in the (001) plane at energy scales of +12 eV near the nucleus and of -700 meV extending away from the dopants. These features are generally neglected in effective mass theory and will affect the coupling between the donor electron and the phosphorus nucleus. Our density functional calculations reveal detail in the densities and potentials of the dopants which are not evident in calculations that do not include explicit treatment of the phosphorus donor atom and relaxation of the crystal lattice. These details can also be used to parameterize tight-binding models for simulation of large-scale devices.Comment: 22 pages, 8 figure

On gigahertz spectral turnovers in pulsars

Pulsars are known to emit non-thermal radio emission that is generally a power-law function of frequency. In some cases, a turnover is seen at frequencies around 100~MHz. Kijak et al. have reported the presence of a new class of ''Gigahertz Peaked Spectrum'' (GPS) pulsars that show spectral turnovers at frequencies around 1 GHz. We apply a model based on free-free thermal absorption to explain these turnovers in terms of surrounding material such as the dense environments found in HII regions, Pulsar Wind Nebulae (PWNe), or in cold, partially ionized molecular clouds. We show that the turnover frequency depends on the electron temperature of the environment close to the pulsar, as well as the emission measure along the line of sight. We fitted this model to the radio fluxes of known GPS pulsars and show that it can replicate the GHz turnover. From the thermal absorption model, we demonstrate that normal pulsars would exhibit a GPS-like behaviour if they were in a dense environment. We discuss the application of this model in the context of determining the population of neutron stars within the central parsec of the Galaxy. We show that a non-negligible fraction of this population might exhibit high-frequency spectral turnovers, which has implications on the detectability of these sources in the Galactic centre.Comment: 7 pages, 3 figures, Accepted for publication in MNRA

Stalag XI B

Stalag XI B was a prisoner of war camp used by the Germans during the war. It was not like the prison camps such as Buchenwald, which held political prisoners, but was one like the many others located throughout Germany. These camps contained prisoners from other armies, such as Indians, Czechs, Poles, British, French, Russian, and American. The troops captured all over the different fronts were brought to the interior to be held there for the duration

Paul B. Sears: Lessons in Classroom, Field and Living Room

Author Institution: Department of Biology, University of New MexicoPaul B. Sears was kind and humble. He disliked false pretense and always was appreciative of the common man. He noted that the goal of teaching was to help students along the road so they could surpass the achievements of the teacher. Sears taught that a permanently balanced relationship with the environment was possible by prudent and skillful use of resources to obtain the maximum good for the longest time. His skills as a speaker, writer and artist enhanced his teaching and publications. A major goal of his teaching was to help students reconstruct the past, appreciate and understand the complexities and interactions of the present and thus knowledgeably predict the futures. Sears was active and still eager to learn and to interact with students even in the last years of his life

Height Perception of Bed Bugs, \u3cem\u3eCimex lectularius\u3c/em\u3e

It has been demonstrated that there is no significant difference in Bed bug preference for colored columns of two heights and that Bed bugs tend to hide in harborages when not stimulated. More information, however, is still needed on their visual perception and general behavior. The following study investigated height perception of Bed bugs by determining the total number of bugs that migrated toward Bed bug interceptors representing different elevations over several trials. A significant difference was found between the number of bugs that migrated toward the control and experimental elevations (3”, 6”, 9”) and the number that migrated toward the general arena area. In addition, it was observed that Bed bugs like aggregating together and prefer secluded areas and dark places. They were also found to be weaker than expected. The results of this study revealed the need to continue learning more about Bed bug behavior and senses