55 research outputs found
Quantum Transport in Semiconductor Nanostructures
I. Introduction (Preface, Nanostructures in Si Inversion Layers,
Nanostructures in GaAs-AlGaAs Heterostructures, Basic Properties).
II. Diffusive and Quasi-Ballistic Transport (Classical Size Effects, Weak
Localization, Conductance Fluctuations, Aharonov-Bohm Effect, Electron-Electron
Interactions, Quantum Size Effects, Periodic Potential).
III. Ballistic Transport (Conduction as a Transmission Problem, Quantum Point
Contacts, Coherent Electron Focusing, Collimation, Junction Scattering,
Tunneling).
IV. Adiabatic Transport (Edge Channels and the Quantum Hall Effect, Selective
Population and Detection of Edge Channels, Fractional Quantum Hall Effect,
Aharonov-Bohm Effect in Strong Magnetic Fields, Magnetically Induced Band
Structure).Comment: 111 pages including 109 figures; this review from 1991 has retained
much of its usefulness, but it was not yet available electronicall
The need for focused, hard X-ray investigations of the Sun
Understanding accelerated particles at the Sun is one of the most important problems in heliophysics. Flare-accelerated particles have huge energies; are an important source of particles in the heliosphere; and are the most important corollary to other areas of high-energy astrophysics. This paper describes the scientific motivation for X-ray studies of particle acceleration at the Sun
The need for focused, hard X-ray investigations of the Sun
Understanding the nature of energetic particles in the solar atmosphere is
one of the most important outstanding problems in heliophysics.
Flare-accelerated particles compose a huge fraction of the flare energy budget;
they have large influences on how events develop; they are an important source
of high-energy particles found in the heliosphere; and they are the single most
important corollary to other areas of high-energy astrophysics. Despite the
importance of this area of study, this topic has in the past decade received
only a small fraction of the resources necessary for a full investigation. For
example, NASA has selected no new Explorer-class instrument in the past two
decades that is capable of examining this topic. The advances that are
currently being made in understanding flare-accelerated electrons are largely
undertaken with data from EOVSA (NSF), STIX (ESA), and NuSTAR (NASA
Astrophysics). This is despite the inclusion in the previous Heliophysics
decadal survey of the FOXSI concept as part of the SEE2020 mission, and also
despite NASA's having invested heavily in readying the technology for such an
instrument via four flights of the FOXSI sounding rocket experiment. Due to
that investment, the instrumentation stands ready to implement a hard X-ray
mission to investigate flare-accelerated electrons. This white paper describes
the scientific motivation for why this venture should be undertaken soon.Comment: White paper submitted to the Decadal Survey for Solar and Space
Physics (Heliophysics) 2024-2033; 15 pages, 5 figure
The need for focused, hard X-ray investigations of the Sun
Understanding accelerated particles at the Sun is one of the most important problems in heliophysics. Flare-accelerated particles have huge energies; are an important source of particles in the heliosphere; and are the most important corollary to other areas of high-energy astrophysics. This paper describes the scientific motivation for X-ray studies of particle acceleration at the Sun
Monitoring conterminous United States (CONUS) land cover change with Web-Enabled Landsat Data (WELD)
A Dosimetric Evaluation of MiniPIX Performance Using In-situ and Simulated Environments
Space weather is becoming increasingly relevant as human activity in space and around grows. Primary contributors to this space radiation are galactic cosmic rays (GCRs) which continue to mystify scientists with their high energies and unknown origins. Despite the unknowns, active monitoring of the radiation environment beyond the Earth’s surface is important for the safety of commercial airlines and astronauts. This thesis examines the use of a MiniPIX camera as a relatively low-cost, portable radiation dosimeter used on-board high altitude balloon flights under the High Altitude Student Platform (HASP). The MiniPIX was housed within a miniature container designed to replicate the structure of the International Space Station (ISS). The goal of this construction is to model a complex and exotic environment, such as the ISS, using a simplified representation in attempt to reduce the high dependence of simulations for monitoring the dose received by human on commercial flights or in space by generalizing this methodology to other applications. Its performance is compared to simulations executed by the FLUKA transport code which strive to replicate the atmospheric environment and GCR sources during the HASP missions. The use of the simulations in this context is to validate the configuration flown on the balloon. The results from the simulations are not directly comparable to those from the balloon, but characteristic features within the simulated data are present. Lastly, results from experiments and simulations performed by others are examined and compared to the results from the HASP mission and the simulations performed in this study.Physics, Department ofHonors Colleg
Reaktionen der Azido- und Isocyanatorhodium(I)-Komplexetrans-(Ph3P)2Rh(CO)X mit dem Nitrosyl-Kation in Gegenwart von Alkoholen
Nested Machine Learning Facilitates Increased Sequence Content for Large-Scale Automated High Resolution Melt Genotyping
High Resolution Melt (HRM) is a versatile and rapid post-PCR DNA analysis technique primarily used to differentiate sequence variants among only a few short amplicons. We recently developed a one-vs-one support vector machine algorithm (OVO SVM) that enables the use of HRM for identifying numerous short amplicon sequences automatically and reliably. Herein, we set out to maximize the discriminating power of HRM + SVM for a single genetic locus by testing longer amplicons harboring significantly more sequence information. Using universal primers that amplify the hypervariable bacterial 16 S rRNA gene as a model system, we found that long amplicons yield more complex HRM curve shapes. We developed a novel nested OVO SVM approach to take advantage of this feature and achieved 100% accuracy in the identification of 37 clinically relevant bacteria in Leave-One-Out-Cross-Validation. A subset of organisms were independently tested. Those from pure culture were identified with high accuracy, while those tested directly from clinical blood bottles displayed more technical variability and reduced accuracy. Our findings demonstrate that long sequences can be accurately and automatically profiled by HRM with a novel nested SVM approach and suggest that clinical sample testing is feasible with further optimization
Texture of MBE grown Cr films on α-Al2O3(0001): the occurrence of Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) related orientation relationships
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