36 research outputs found
Selling the Southern Highlands: Tourism and Community Development in the Mountain South
Focusing on Buncombe County, North Carolina, Blount County, Tennessee, and Sevier County, Tennessee as representative resort areas in the mountain South, this study recognizes tourism as a central factor in the historical development of the region\u27s cultural identity, economy, and landscape. In studying the variant development patterns of resort communities in the southern highlands, it is apparent that tourism has simultaneously produced both continuity and change as well as positive and negative consequences. On the one hand, tourism has often served as a source of economic, cultural, and environmental preservation. Tourism has helped to maintained cultural distinctiveness, historical identity, and a sense of place in the mountain South. Likewise, tourism has also sustained many of the economic qualities traditionally associated with the region, including a dependency on external capital, uneven distribution of economic benefits, an unorganized labor force, and seasonal employment patterns. Moreover, since scenic beauty and healthy climate have long been a main attraction for tourists, tourism has often provided the economic rationale for the protection of the environment.
On the other hand, the growth of tourism has also modified many of the qualities traditionally associated with the region. Considering the environmental changes brought by rapid commercial development and second home construction, or the cultural adaptations induced by contrived attractions and interactions between visitors and local residents in a tourist setting, or the employment, revenue, and economic dependence generated by the mass travel industry, it is clear that tourism has been a major source of change in the southern mountains. In many ways tourism has been an important factor in the transformation of the landscape as well as the modernization of the region\u27s culture and economy over the last century. Depending on the context in which it is pursued, tourism can be a healthy, sustainable development strategy that enhances the beauty of the landscape as well as the cultural foundation of the community, or it can hinder economic diversification, mar the scenery, and destroy the sense of community
Respiratory Anomaly Detection using Reflected Infrared Light-wave Signals
In this study, we present a non-contact respiratory anomaly detection method
using incoherent light-wave signals reflected from the chest of a mechanical
robot that can breathe like human beings. In comparison to existing radar and
camera-based sensing systems for vitals monitoring, this technology uses only a
low-cost ubiquitous light source (e.g., infrared light emitting diode) and
sensor (e.g., photodetector). This light-wave sensing (LWS) system recognizes
different breathing anomalies from the variations of light intensity reflected
from the chest of the robot within a 0.5m-1.5m range. The anomaly detection
model demonstrates up to 96.6% average accuracy in classifying 7 different
types of breathing data using machine learning. The model can also detect
faulty data collected by the system that does not contain breathing
information. The developed system can be utilized at home or healthcare
facilities as a smart, non-contact and discreet respiration monitoring method.Comment: 5 pages, 4 figures, submitted to IEEE conferenc
Effect of nonhydrostatic pressure on the superconducting kagome metal CsVSb
High-pressure single-crystal x-ray diffraction experiments reveal that the
superconducting kagome metal CsVSb transforms from hexagonal ()
to monoclinic () symmetry above 10 GPa if nonhydrostatic pressure
conditions are created in a diamond anvil cell with silicon oil as
pressure-transmitting medium. This is contrary to the behavior of CsVSb
under quasi-hydrostatic conditions in neon, with the hexagonal symmetry
retained up to at least 20 GPa. Monoclinic distortion leaves the kagome planes
almost unchanged but deforms honeycomb nets of the Sb atoms. Using ab initio
density-functional calculations, we show that this distortion facilitates the
pressure-induced shift of van Hove singularities away from the Fermi level and
assists in the Fermi surface reconstruction caused by the formation of
interlayer Sb-Sb bonds, thus adding a structural transition component to the
reentrant behavior of CsVSb.Comment: 5 pages, 4 figures, 2 table
Non-contact respiration monitoring
This paper covers the research and development process of creating a phantom lung (breathing robot) to test a sensor for viability of tracking respiration (the parent project). An inanimate subject was needed as it is difficult to get permission and do testing on human subjects
Role of Sb in the superconducting kagome metal CsV$3Sb5 revealed by its anisotropic compression
Pressure evolution of the superconducting kagome metal CsVSb is
studied with single-crystal x-ray diffraction and density-functional
band-structure calculations. A highly anisotropic compression observed up to 5
GPa is ascribed to the fast shrinkage of the Cs-Sb distances and suppression of
Cs rattling motion. This prevents Sb displacements required to stabilize the
three-dimensional charge-density-wave (CDW) order and elucidates the
disappearance of the CDW already at 2 GPa despite only minor changes in the
electronic structure of the normal state. At higher pressures, vanadium bands
still change only marginally, whereas antimony bands undergo a major
reconstruction caused by the gradual formation of the interlayer Sb-Sb bonds.
Our results exclude pressure tuning of vanadium kagome bands as the main
mechanism for the non-trivial evolution of superconductivity in real-world
kagome metals. Concurrently, we establish the central role of Sb atoms in the
stabilization of a three-dimensional CDW and Fermi surface reconstruction.Comment: published versio
Nuclear excitation of the Th isomer via defect states in doped crystals
When Th nuclei are doped in CaF crystals, a set of electronic defect
states appears in the crystal bandgap which would otherwise provide complete
transparency to vacuum-ultraviolet radiation. The coupling of these defect
states to the 8 eV Th nuclear isomer in the CaF crystal is
investigated theoretically. We show that although previously viewed as a
nuisance, the defect states provide a starting point for nuclear excitation via
electronic bridge mechanisms involving stimulated emission or absorption using
an optical laser. The rates of these processes are at least two orders of
magnitude larger than direct photoexcitation of the isomeric state using
available light sources. The nuclear isomer population can also undergo
quenching when triggered by the reverse mechanism, leading to a fast and
controlled decay via the electronic shell. These findings are relevant for a
possible solid-state nuclear clock based on the Th isomeric
transition
Pressure evolution of electron dynamics in the superconducting kagome metal CsVSb
The coexistence of the charge-density wave (CDW) and superconducting phases
and their tunability under external pressure remains one of the key points in
understanding the electronic structure of VSb ( = K, Rb, Cs)
kagome metals. Here, we employ synchrotron-based infrared spectroscopy assisted
by density-functional calculations to study the pressure evolution of the
electronic structure at room temperature up to 17 GPa experimentally. The
optical spectrum of CsVSb is characterized by the presence of localized
carriers seen as a broad peak at finite frequencies in addition to the
conventional metallic Drude response. The pressure dependence of this
low-energy peak reflects the re-entrant behavior of superconductivity and may
be interpreted in terms of electron-phonon coupling, varying with the growth
and shrinkage of the Fermi surface. Moreover, drastic modifications in the
low-energy interband absorptions are observed upon the suppression of CDW.
These changes are related to the upward shift of the Sb2 band that
eliminates part of the Fermi surface around the -point, whereas band saddle
points do not move significantly. These observations shed new light on the
mixed electronic and lattice origin of the CDW in CsVSb
Driven electronic bridge processes via defect states in Th-doped crystals
The electronic defect states resulting from doping Th in CaF
offer a unique opportunity to excite the nuclear isomeric state Th at
approximately 8 eV via electronic bridge mechanisms. We consider bridge schemes
involving stimulated emission and absorption using an optical laser. The role
of different multipole contributions, both for the emitted or absorbed photon
and nuclear transition, to the total bridge rates are investigated
theoretically. We show that the electric dipole component is dominant for the
electronic bridge photon. In contradistinction, the electric quadrupole channel
of the Th isomeric transition plays the dominant role for the bridge
processes presented. The driven bridge rates are discussed in the context of
background signals in the crystal environment and of implementation methods. We
show that inverse electronic bridge processes quenching the isomeric state
population can improve the performance of a solid-state nuclear clock based on
Th
Needs, trends, and advances in scintillators for radiographic imaging and tomography
Scintillators are important materials for radiographic imaging and tomography
(RadIT), when ionizing radiations are used to reveal internal structures of
materials. Since its invention by R\"ontgen, RadIT now come in many modalities
such as absorption-based X-ray radiography, phase contrast X-ray imaging,
coherent X-ray diffractive imaging, high-energy X- and ray radiography
at above 1 MeV, X-ray computed tomography (CT), proton imaging and tomography
(IT), neutron IT, positron emission tomography (PET), high-energy electron
radiography, muon tomography, etc. Spatial, temporal resolution, sensitivity,
and radiation hardness, among others, are common metrics for RadIT performance,
which are enabled by, in addition to scintillators, advances in high-luminosity
accelerators and high-power lasers, photodetectors especially CMOS pixelated
sensor arrays, and lately data science. Medical imaging, nondestructive
testing, nuclear safety and safeguards are traditional RadIT applications.
Examples of growing or emerging applications include space, additive
manufacturing, machine vision, and virtual reality or `metaverse'. Scintillator
metrics such as light yield and decay time are correlated to RadIT metrics.
More than 160 kinds of scintillators and applications are presented during the
SCINT22 conference. New trends include inorganic and organic scintillator
heterostructures, liquid phase synthesis of perovskites and m-thick films,
use of multiphysics models and data science to guide scintillator development,
structural innovations such as photonic crystals, nanoscintillators enhanced by
the Purcell effect, novel scintillator fibers, and multilayer configurations.
Opportunities exist through optimization of RadIT with reduced radiation dose,
data-driven measurements, photon/particle counting and tracking methods
supplementing time-integrated measurements, and multimodal RadIT.Comment: 45 pages, 43 Figures, SCINT22 conference overvie
Cryogenic Memory Architecture Integrating Spin Hall Effect based Magnetic Memory and Superconductive Cryotron Devices
One of the most challenging obstacles to realizing exascale computing is
minimizing the energy consumption of L2 cache, main memory, and interconnects
to that memory. For promising cryogenic computing schemes utilizing Josephson
junction superconducting logic, this obstacle is exacerbated by the cryogenic
system requirements that expose the technology's lack of high-density,
high-speed and power-efficient memory. Here we demonstrate an array of
cryogenic memory cells consisting of a non-volatile three-terminal magnetic
tunnel junction element driven by the spin Hall effect, combined with a
superconducting heater-cryotron bit-select element. The write energy of these
memory elements is roughly 8 pJ with a bit-select element, designed to achieve
a minimum overhead power consumption of about 30%. Individual magnetic memory
cells measured at 4 K show reliable switching with write error rates below
, and a 4x4 array can be fully addressed with bit select error rates
of . This demonstration is a first step towards a full cryogenic
memory architecture targeting energy and performance specifications appropriate
for applications in superconducting high performance and quantum computing
control systems, which require significant memory resources operating at 4 K.Comment: 10 pages, 6 figures, submitte