Spruce Budworm and Other Lepidopterous Prey of Eumenid Wasps (Hymenoptera: Eumenidae) in Spruce-Fir Forests of Maine

Three species of eumenid wasps, Ancistrocerus adiabatus, Ancistrocerus antilope, and Euodynerus Ieucomelas, accepted and provisioned trap-nesting blocks with lepidopterous larvae, A pyralid. Nephopteryx sp., was the most commonly provisioned prey. A. adiabarus and E. leucomelas preyed on late instars of the spruce budworm, Choristoneura fumiferana: however. budworms accounted for only 6% of the provisioned prey. Estimates of budworm population densities before and after wasp predation, and subsample-s of provisioned prey indicated no significant reductions i = 0.065%) in budworm populations attributable to trap-nesting wasps

Prospects for the future of narrow bandgap materials

Recently there has been greatly expended interest in narrow bandgap materials. Modern epitaxial techniques and the growing interest in nanostructures have provided areas of application for some of the unique properties of the narrow bandgap material. As always, one of the primary sources of interest is the small bandgap which makes them the material of choice for many applications in the infrared. However, in recent years their other unique properties have been the basis for a broader set of interests in narrow bandgap semiconductors. The type II band offsets (InAs/GaSb) have been the basis for novel tunnel devices and infrared superlattices. The very small effective masses inherent in small bandgap materials make them the obvious candidates in which to observe quantum confinement effects at larger dimensions than in materials of larger effective mass and wider gap. The ease of making electrical contact to some of the materials (ohmic contact to n-InAs) has made them the material of choice for electrical nanostructures. The ability to put in large amounts of magnetic ions to make magnetic semiconductors has led to a number of novel properties. The technical importance of a narrow bandgap and the unique applications promised by some of the other properties of these materials bode well for substantial research in narrow bandgap semiconductors well into the next decade

Diamond-Like Carbon film from Liquid Gas on Metallic Substrates

Liquid gas was used to produce DLC films on Cu, Al and steel substrates by DC plasma technique. The absorption in IR reflectance indicates, grown films are DLC. By deconvolution of room temperature UV-visible spectra of the films grown at 50 mtorr and 200${}^\circ$C, in addition to the spectra lines reported for CL, PL, PLC and ESR, some new spectra lines were obtained. We also, have seen exciton absorption line at room temperature.Comment: 6 pages, Postscript, 2 figure

Multiplexed Memory-Insensitive Quantum Repeaters

Long-distance quantum communication via distant pairs of entangled quantum bits (qubits) is the first step towards more secure message transmission and distributed quantum computing. To date, the most promising proposals require quantum repeaters to mitigate the exponential decrease in communication rate due to optical fiber losses. However, these are exquisitely sensitive to the lifetimes of their memory elements. We propose a multiplexing of quantum nodes that should enable the construction of quantum networks that are largely insensitive to the coherence times of the quantum memory elements.Comment: 5 pages, 4 figures. Accepted for publication in PR

Mapping of AlxGa1–xAs band edges by ballistic electron emission spectroscopy

We have employed ballistic electron emission microscopy (BEEM) to study the energy positions in the conduction band of AlxGa1 – xAs. Epilayers of undoped AlxGa1 – xAs were grown by molecular beam epitaxy on conductive GaAs substrates. The Al composition x took on values of 0, 0.11, 0.19, 0.25, 0.50, 0.80 and 1 so that the material was examined in both the direct and indirect band gap regime. The AlxGa1 – xAs layer thickness was varied from 100 to 500 Å to ensure probing of bulk energy levels. Different capping layers and surface treatments were explored to prevent surface oxidation and examine Fermi level pinning at the cap layer/AlxGa1 – xAs interface. All samples were metallized ex situ with a 100 Å Au layer so that the final BEEM structure is of the form Au/capping layer/AlxGa1 – xAs/bulk GaAs. Notably we have measured the Schottky barrier height for Au on AlxGa1 – xAs. We have also probed the higher lying band edges such as the X point at low Al concentrations and the L point at high Al concentrations. Variations of these critical energy positions with Al composition x were mapped out in detail and compared with findings from other studies. Local variations of these energy positions were also examined and found to be on the order of 30–50 meV. The results of this study suggest that BEEM can provide accurate positions for multiple energy levels in a single semiconductor structure

Real-time extraction of growth rates from rotating substrates during molecular-beam epitaxy

We present a method for measuring molecular‐beam epitaxy growth rates in near real‐time on rotating substrates. This is done by digitizing a video image of the reflection high‐energy electron diffraction screen, automatically tracking and measuring the specular spot width, and using numerical techniques to filter the resulting signal. The digitization and image and signal processing take approximately 0.4 s to accomplish, so this technique offers the molecular‐beam epitaxy grower the ability to actively adjust growth times in order to deposit a desired layer thickness. The measurement has a demonstrated precision of approximately 2%, which is sufficient to allow active control of epilayer thickness by counting monolayers as they are deposited. When postgrowth techniques, such as frequency domain analysis, are also used, the reflection high‐energy electron diffraction measurement of layer thickness on rotating substrates improves to a precision of better than 1%. Since all of the components in the system described are commercially available, duplication is straightforward

Reflection high-energy electron diffraction studies of the growth of lnAs/Ga_(1-x)In_xSb strained-layer superlattices

We have used reflection high‐energy electron diffraction to study the surface periodicity of the growth front of InAs/GaInSb strained‐layer superlattices (SLSs). We found that the apparent surface lattice spacing reproducibly changed during layers which subsequent x‐ray measurements indicated were coherently strained. Abrupt changes in the measured streak spacings were found to be correlated to changes in the growth flux. The profile of the dynamic streak spacing was found to be reproducible when comparing consecutive periods of a SLSs or different SLSs employing the same shuttering scheme at the InAs/GaInSb interface. Finally, when the interface shuttering scheme was changed, it was found that the dynamic streak separation profile also changed. Large changes in the shuttering scheme led to dramatic differences in the streak separation profile, and small changes in the shuttering scheme led to minor changes in the profile. In both cases, the differences in the surface periodicity profile occurred during the parts of the growth where the incident fluxes differed

Intrinsic transverse parton momenta in deeply inelastic reactions

Intrinsic transverse parton momenta pT play an important role in the understanding of azimuthal/spin asymmetries in semi-inclusive deep-inelastic scattering (SIDIS) and the Drell-Yan process (DY). We review and update what is presently known about pT from these processes. In particular, we address the question to which extent data support the popular Gauss model for the pT-distributions. We find that the Gauss model works very well, and observe that the intrinsic transverse momenta in SIDIS and DY are compatible, which is a support for the factorization approach. As a byproduct we recover a simple but practical way of taking into account the energy dependence of pT-distributions.Comment: 19 pages, 11 figure

‘Multi-directional management’: Exploring the challenges of performance in the World Class Programme environment

Driven by the ever-increasing intensity of Olympic competition and the ‘no compromise – no stone unturned’ requirements frequently addressed by HM Government and its main agency, UK Sport, a change in culture across Olympic team landscapes is a common occurrence. With a focus on process, this paper presents reflections from eight current or recently serving UK Olympic sport Performance Directors on their experiences of creating and disseminating their vision for their sport, a vital initial activity of the change initiative. To facilitate a broad overview of this construct, reflections are structured around the vision’s characteristics and foundations, how it is delivered to key stakeholder groups, how it is influenced by these groups, the qualities required to ensure its longevity and its limitations. Emerging from these perceptions, the creation and maintenance of a shared team vision was portrayed as a highly dynamic task requiring the active management of a number of key internal and external stakeholders. Furthermore, the application of ‘dark’ traits and context-specific expertise were considered critical attributes for the activity’s success. Finally, recent calls for research to elucidate the wider culture optimisation process are reinforced