1,468 research outputs found
Gate Tunable Dissipation and "Superconductor-Insulator" Transition in Carbon Nanotube Josephson Transistors
Dissipation is ubiquitous in quantum systems, and its interplay with
fluctuations is critical to maintaining quantum coherence. We experimentally
investigate the dissipation dynamics in single-walled carbon nanotubes coupled
to superconductors. The voltage-current characteristics display gate-tunable
hysteresis, with sizes that perfectly correlate with the normal state
resistance RN, indicating the junction undergoes a periodic modulation between
underdamped and overdamped regimes. Surprisingly, when a device's Fermi-level
is tuned through a local conductance minimum, we observe a gate-controlled
transition from superconducting-like to insulating-like states, with a
"critical" R_N value of about 8-20 kohm.Comment: Figures revised to improve clarity. Accepted for publication by
Physical Review Letter
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Who Dominate TDI? A Big Data Evidence from DMO and UGC Short Videos
Abstract
In the formation of tourism destination image (TDI), understanding and being able to measure, analyze, compare, and contrast the images projected by user-generated content(UGC) and destination marketing organizations(DMOs) is crucial in tourism management and destination marketing. This study aims to propose a specific way to measure and compare UGC and DMO projected images within 249 short videos. Using machine learning algorithms, four indicators (the number of short videos, the number of likes, comments and shares) were identified to measure the influences of DMO and UGC short videos, and extracted 7 dimensions representing the destination image extracted through video content analysis, namely, nature environment, infrastructure, culture and art, people, food and beverage, specific activities, and transportation. The data analysis further revealed statistical differences in several dimensions of these images at different destination’s life cycle. Theoretical and practical implications were also discussed.
Keywords
tourism destination image, destination’s life cycle, short video, video captaining,brand hijac
Quantum Transport and Field Induced Insulating States in Bilayer Graphene pnp Junctions
We perform transport measurements in high quality bilayer graphene pnp
junctions with suspended top gates. At a magnetic field B=0, we demonstrate
band gap opening by an applied perpendicular electric field, with an On/Off
ratio up to 20,000 at 260mK. Within the band gap, the conductance decreases
exponentially by 3 orders of magnitude with increasing electric field, and can
be accounted for by variable range hopping with a gate-tunable density of
states, effective mass, and localization length. At large B, we observe quantum
Hall conductance with fractional values, which arise from equilibration of edge
states between differentially-doped regions, and the presence of an insulating
state at filling factor {\nu}=0. Our work underscores the importance of bilayer
graphene for both fundamental interest and technological applications.Comment: 4 figures, to appear in Nano Lett. Minor typos correcte
Electrical Transport in High Quality Graphene pnp Junctions
We fabricate and investigate high quality graphene devices with contactless,
suspended top gates, and demonstrate formation of graphene pnp junctions with
tunable polarity and doping levels. The device resistance displays distinct
oscillations in the npn regime, arising from the Fabry-Perot interference of
holes between the two pn interfaces. At high magnetic fields, we observe
well-defined quantum Hall plateaus, which can be satisfactorily fit to
theoretical calculations based on the aspect ratio of the device.Comment: to appear in a special focus issue in New Journal of Physic
Gas kinematics and star formation in the filamentary molecular cloud G47.06+0.26
We performed a multi-wavelength study toward the filamentary cloud
G47.06+0.26 to investigate the gas kinematics and star formation. We present
the 12CO (J=1-0), 13CO (J=1-0) and C18O (J=1-0) observations of G47.06+0.26
obtained with the Purple Mountain Observation (PMO) 13.7 m radio telescope to
investigate the detailed kinematics of the filament. The 12CO (J=1-0) and 13CO
(J=1-0) emission of G47.06+0.26 appear to show a filamentary structure. The
filament extends about 45 arcmin (58.1 pc) along the east-west direction. The
mean width is about 6.8 pc, as traced by the 13CO (J=1-0) emission. G47.06+0.26
has a linear mass density of about 361.5 Msun/pc. The external pressure (due to
neighboring bubbles and H II regions) may help preventing the filament from
dispersing under the effects of turbulence. From the velocity-field map, we
discern a velocity gradient perpendicular to G47.06+0.26. From the Bolocam
Galactic Plane Survey (BGPS) catalog, we found nine BGPS sources in
G47.06+0.26, that appear to these sources have sufficient mass to form massive
stars. We obtained that the clump formation efficiency (CFE) is about 18% in
the filament. Four infrared bubbles were found to be located in, and adjacent
to, G47.06+0.26. Particularly, infrared bubble N98 shows a cometary structure.
CO molecular gas adjacent to N98 also shows a very intense emission. H II
regions associated with infrared bubbles can inject the energy to surrounding
gas. We calculated the kinetic energy, ionization energy, and thermal energy of
two H II regions in G47.06+0.26. From the GLIMPSE I catalog, we selected some
Class I sources with an age of about 100000 yr, which are clustered along the
filament. The feedback from the H II regions may cause the formation of a new
generation of stars in filament G47.06+0.26.Comment: 10 pages, 11 figures, accepted for publication in A&
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