13,504 research outputs found
Wireless Biosensing Network for Drivers' Health Monitoring
Biosensors integrated into the vehicle controller area network are used for detecting symptoms such as anxiety, pain, and fatigue that may affect driving safety. The proposed system provides a flexible option for implementation in a diverse range of mass-produced automotive accessories without affecting the driver's movement
Ultrasensitive and Wide-Bandwidth Thermal Measurements of Graphene at Low Temperatures
Graphene is a material with remarkable electronic properties[1] and exceptional thermal transport
properties near room temperature, which have been well examined and understood[2, 3].
However at very low temperatures the thermodynamic and thermal transport properties are much
less well explored[4, 5] and somewhat surprisingly, is expected to exhibit extreme thermal isolation.
Here we demonstrate an ultra-sensitive, wide-bandwidth measurement scheme to probe the
thermal transport and thermodynamic properties of the electron gas of graphene. We employ
Johnson noise thermometry at microwave frequency to sensitively measure the temperature of the
electron gas with resolution of 4mK/√Hz and a bandwidth of 80 MHz. We have measured the
electron-phonon coupling from 2-30 K at a charge density of 2 •10^(11)cm^(-2). Utilizing bolometric
mixing, we have sensed temperature oscillations with period of 430 ps and have determined the
heat capacity of the electron gas to be 2 • 10^(-21)J/(K •µm^2) at 5 K which is consistent with that
of a two dimensional, Dirac electron gas. These measurements suggest that graphene-based devices
together with wide bandwidth noise thermometry can generate substantial advances in the
areas of ultra-sensitive bolometry[6], calorimetry[7], microwave and terahertz photo-detection[8],
and bolometric mixing for applications in areas such as observational astronomy[9] and quantum
information and measurement[10]
Flavoured Soft Leptogenesis
We study the impact of flavour in ``soft leptogenesis'' (leptogenesis induced
by soft supersymmetry breaking terms). We address the question of how flavour
effects can affect the region of parameters in which successful soft
leptogenesis induced by CP violation in the right-handed sneutrino mixing is
possible. We find that for decays which occur in the intermediate to strong
washout regimes for all flavours, the produced total asymmetry can be up
to a factor larger than the one predicted with flavour effects
being neglected. This enhancement, permits slightly larger values of the
required lepton violating soft bilinear term.Comment: 20 pages, 5 figures. Version accepted in JHEP. Results unchange
Quantum phase transition induced by Dzyaloshinskii-Moriya in the kagome antiferromagnet
We argue that the S=1/2 kagome antiferromagnet undergoes a quantum phase
transition when the Dzyaloshinskii-Moriya coupling is increased. For
the system is in a moment-free phase and for the system develops
antiferromagnetic long-range order. The quantum critical point is found to be
using exact diagonalizations and finite-size scaling. This
suggests that the kagome compound ZnCu_6_3$ may be in a quantum
critical region controlled by this fixed point.Comment: 5 pages, 4 figures; v2: add. data included, show that D=0.1J is at a
quantum critical poin
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