106 research outputs found
Reinforced concrete in Britain, 1897-1908
SIGLEAvailable from British Library Document Supply Centre- DSC:D42208/82 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Case Study: The Impact Of Emerging Technologies On Cybersecurity Education And Workforces
A qualitative case study focused on understanding what steps are needed to prepare the cybersecurity workforces of 2026-2028 to work with and against emerging technologies such as Artificial Intelligence and Machine Learning. Conducted through a workshop held in two parts at a cybersecurity education conference, findings came both from a semi-structured interview with a panel of experts as well as small workgroups of professionals answering seven scenario-based questions. Data was thematically analyzed, with major findings emerging about the need to refocus cybersecurity STEM at the middle school level with problem-based learning, the disconnects between workforce operations and cybersecurity operators, the distrust of Non-Traditional Training Programs, and the need to build digital security generalists’ curriculum and training. Recommendations are also made for possible next steps
Temporary silicon-tethered ring-closing metathesis approach to polyketide fragments : asymmetric synthesis of the C1-C30 fragment of amphidinol 3
Structure characterization of hard sphere packings in amorphous and crystalline states
The channel size distribution in hard sphere systems, based on the local
neighbor correlation of four particle positions, is investigated for all volume
fractions up to jamming. For each particle, all three particle combinations of
neighbors define channels, which are relevant for the concept of caging. The
analysis of the channel size distribution is shown to be very useful in
distinguishing between gaseous, liquid, partially and fully crystallized, and
glassy (random) jammed states. A common microstructural feature of four
coplanar particles is observed in crystalline and glassy jammed states,
suggesting the presence of "hidden" two-dimensional order in three-dimensional
random close packings.Comment: 5 pages, 5 figure
Observation of a large lee wave in the Drake Passage
Lee waves are thought to play a prominent role in Southern Ocean dynamics, facilitating a transfer of energy from the jets of the Antarctic Circumpolar Current to microscale, turbulent motions important in water mass transformations. Two EM-APEX profiling floats deployed in the Drake Passage during the Diapycnal and Isopycnal Mixing Experiment (DIMES) independently measured a 120 ± 20-m vertical amplitude lee wave over the Shackleton Fracture Zone. A model for steady EM-APEX motion is developed to calculate absolute vertical water velocity, augmenting the horizontal velocity measurements made by the floats. The wave exhibits fluctuations in all three velocity components of over 15 cm s−1 and an intrinsic frequency close to the local buoyancy frequency. The wave is observed to transport energy and horizontal momentum vertically at respective peak rates of 1.3 ± 0.2 W m−2 and 8 ± 1 N m−2. The rate of turbulent kinetic energy dissipation is estimated using both Thorpe scales and a method that isolates high-frequency vertical kinetic energy and is found to be enhanced within the wave to values of order 10−7 W kg−1. The observed vertical flux of energy is significantly larger than expected from idealized numerical simulations and also larger than observed depth-integrated dissipation rates. These results provide the first unambiguous observation of a lee wave in the Southern Ocean with simultaneous measurements of its energetics and dynamics
Structural and dynamical properties of liquid Si. An orbital-free molecular dynamics study
Several static and dynamic properties of liquid silicon near melting have
been determined from an orbital free {\em ab-initio} molecular dynamics
simulation. The calculated static structure is in good agreement with the
available X-ray and neutron diffraction data. The dynamical structure shows
collective density excitations with an associated dispersion relation which
closely follows recent experimental data. It is found that liquid silicon can
not sustain the propagation of shear waves which can be related to the power
spectrum of the velocity autocorrelation function. Accurate estimates have also
been obtained for several transport coefficients. The overall picture is that
the dynamic properties have many characteristics of the simple liquid metals
although some conspicuous differences have been found.Comment: 12 pages, 11 figure
Pressure induced structural and dynamical changes in liquid Si. An ab-initio study
The static and dynamic properties of liquid Si at high-pressure have been
studied using the orbital free ab-initio molecular dynamics method. Four
thermodynamic states at pressures 4, 8, 14 and 23 GPa are considered. The
calculated static structure shows qualitative agreement with the available
experimental data. We analize the remarkable structural changes occurring
between 8 and 14 GPa along with its effect on several dynamic properties.Comment: 10 pages, 11 figures. Accepted for publication in Journal of Physics:
Condensed Matte
Theoretical interpretation of the experimental electronic structure of lens shaped, self-assembled InAs/GaAs quantum dots
We adopt an atomistic pseudopotential description of the electronic structure
of self-assembled, lens shaped InAs quantum dots within the ``linear
combination of bulk bands'' method. We present a detailed comparison with
experiment, including quantites such as the single particle electron and hole
energy level spacings, the excitonic band gap, the electron-electron, hole-hole
and electron hole Coulomb energies and the optical polarization anisotropy. We
find a generally good agreement, which is improved even further for a dot
composition where some Ga has diffused into the dots.Comment: 16 pages, 5 figures. Submitted to Physical Review
Prediction of a Strain Induced Conduction Band Minimum in Embedded Quantum Dots
Free standing InP quantum dots have previously been theoretically and
experimentally shown to have a direct band gap across a large range of
experimentally accessible sizes. We demonstrate that when these dots are
embedded coherently within a GaP barrier material, the effects of quantum
confinement in conjunction with coherent strain suggest there will be a
critical diameter of dot (60A), above which the dot is direct, type I, and
below which it is indirect, type II. However, the strain in the system acts to
produce another conduction state with an even lower energy, in which electrons
are localized in small pockets at the interface between the InP dot and the GaP
barrier. Since this conduction state is GaP X_1c-derived and the highest
occupied valence state is InP, Gamma-derived, the fundamental transition is
predicted to be indirect in both real and reciprocal space (``type II'') for
all dot sizes. This effect is peculiar to the strained dot, and is absent in
the free-standing dot
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