99 research outputs found
Formation and Thermal Stability of sub-10 nm Carbon Templates on Si(100)
We report a lithographic process for creating high-resolution (<10 nm) carbon
templates on Si(100). A scanning electron microscope, operating under low
vacuum (10E-6 mbar), produces a carbon-containing deposit ("contamination
resist") on the silicon surface via electron-stimulated dissociation of ambient
hydrocarbons, water and other adsorbed molecules. Subsequent annealing at
temperatures up to 1320 K in ultra-high vacuum removes SiO2 and other
contaminants, with no observable change in dot shape. The annealed structures
are compatible with subsequent growth of semiconductors and complex oxides.
Carbon dots with diameter as low as 3.5 nm are obtained with a 200 us
electron-beam exposure time.Comment: 13 pages, 4 figure
Enhanced Out-of-plane Emission of K+ Mesons observed in Au+Au Collisions at 1 AGeV
The azimuthal angular distribution of K+ mesons has been measured in Au + Au
collisions at 1 AGeV. In peripheral and semi-central collisions, K+ mesons
preferentially are emitted perpendicular to the reaction plane. The strength of
the azimuthal anisotropy of K+ emission is comparable to the one of pions. No
in-plane flow was found for K+ mesons near projectile and target rapidity.Comment: Accepted for publication in Phys. Rev.Let
Development and Performance of the Nanoworkbench: A Four Tip STM for Electrical Conductivity Measurements Down to Sub-micrometer Scales
A multiple-tip ultra-high vacuum (UHV) scanning tunneling microscope (MT-STM)
with a scanning electron microscope (SEM) for imaging and molecular-beam
epitaxy growth capabilities has been developed. This instrument (nanoworkbench)
is used to perform four-point probe conductivity measurements at micrometer
spatial dimension. The system is composed of four chambers, the multiple-tip
STM/SEM chamber, a surface analysis and preparation chamber, a molecular-beam
epitaxy chamber and a load-lock chamber for fast transfer of samples and
probes. The four chambers are interconnected by a unique transfer system based
on a sample box with integrated heating and temperature-measuring capabilities.
We demonstrate the operation and the performance of the nanoworkbench with STM
imaging on graphite and with four-point-probe conductivity measurements on a
silicon-on-insulator (SOI) crystal. The creation of a local FET, whose
dimension and localization are respectively determined by the spacing between
the probes and their position on the SOI surface, is demonstrated.Comment: 39 pages, 15 figure
Evaluating the impact of integrated development: are we asking the right questions? A systematic review [version 2; referees: 2 approved, 1 approved with reservations]
Background: Emerging global transformations - including a new Sustainable Development Agenda - are revealing increasingly interrelated goals and challenges, poised to be addressed by similarly integrated, multi-faceted solutions. Research to date has focused on determining the effectiveness of these approaches, yet a key question remains: are synergistic effects produced by integrating two or more sectors? We systematically reviewed impact evaluations on integrated development interventions to assess whether synergistic, amplified impacts are being measured and evaluated. Methods: The International Initiative for Impact Evaluation’s (3ie) Impact Evaluation Repository comprised our sampling frame (n = 4,339). Following PRISMA guidelines, we employed a three-stage screening and review process. Results: We identified 601 journal articles that evaluated integrated interventions. Seventy percent used a randomized design to assess impact with regard to whether the intervention achieved its desired outcomes. Only 26 of these evaluations, however, used a full factorial design to statistically detect any synergistic effects produced by integrating sectors. Of those, seven showed synergistic effects. Conclusions: To date, evaluations of integrated development approaches have demonstrated positive impacts in numerous contexts, but gaps remain with regard to documenting whether integrated programming produces synergistic, amplified outcomes. Research on these program models needs to extend beyond impact only, and more explicitly examine and measure the synergies and efficiencies associated with linking two or more sectors. Doing so will be critical for identifying effective integrated development strategies that will help achieve the multi-sector SDG agenda
Medium Effects in Kaon and Antikaon Production in Nuclear Collisions at Subthreshold Beam Energies
Production cross sections of K and K mesons have been measured in C+C
collisions at beam energies per nucleon below and near the nucleon-nucleon
threshold. At a given beam energy, the spectral slopes of the K mesons are
significantly steeper than the ones of the K mesons. The excitation
functions for K and K mesons nearly coincide when correcting for the
threshold energy. In contrast, the K yield exceeds the K yield by a
factor of about 100 in proton-proton collisions at beam energies near the
respective nucleon-nucleon thresholds.Comment: Accepted for publication in Phys. Rev. Let
Predicting the impact of Lynch syndrome-causing missense mutations from structural calculations
Accurate methods to assess the pathogenicity of mutations are needed to fully leverage the possibilities of genome sequencing in diagnosis. Current data-driven and bioinformatics approaches are, however, limited by the large number of new variations found in each newly sequenced genome, and often do not provide direct mechanistic insight. Here we demonstrate, for the first time, that saturation mutagenesis, biophysical modeling and co-variation analysis, performed in silico, can predict the abundance, metabolic stability, and function of proteins inside living cells. As a model system, we selected the human mismatch repair protein, MSH2, where missense variants are known to cause the hereditary cancer predisposition disease, known as Lynch syndrome. We show that the majority of disease-causing MSH2 mutations give rise to folding defects and proteasome-dependent degradation rather than inherent loss of function, and accordingly our in silico modeling data accurately identifies disease-causing mutations and outperforms the traditionally used genetic disease predictors. Thus, in conclusion, in silico biophysical modeling should be considered for making genotype-phenotype predictions and for diagnosis of Lynch syndrome, and perhaps other hereditary diseases
Azimuthally anisotropic emission of pions in symmetric heavy-ion collisions
Triple differential cross sections d3 sigma /dp3 for charged pions produced in symmetric heavy-ion collisions were measured with the KaoS magnetic spectrometer at the heavy-ion synchrotron facility SIS at GSI. The correlations between the momentum vectors of charged pions and the reaction plane in 197Au+197Au collisions at an incident energy of 1 GeV/nucleon were determined. We observe, for the first time, an azimuthally anisotropic distribution of pions, with enhanced emission perpendicular to the reaction plane. The anisotropy is most pronounced for pions of high transverse momentum in semicentral collisions
Design for, and Evaluation of Life Cycle Performance
Project evaluation necessarily requires
performance estimates over the project life
cycle. In contrast to new and clean conditions,
extended life performance inherently
introduces additional complexity and variability
in developing such estimates, due
to changing operating environment, maintenance
policies, operating procedures,
equipment availabilities, etc. This paper
discusses the general nature, and the thermal
interaction of power plant components
as individual equipment degradation occurs,
describing overall plant performance trends
and quantifying typical ranges for a given
application. A specific cogeneration example
will be discussed and the economic
effects of life cycle performance with
various plant design assumptions will be
shown. Design considerations to minimize
long term performance degradation will also
be described
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