19,404 research outputs found
Multiparticle Entanglement in the Lipkin-Meshkov-Glick Model
The multiparticle entanglement in the Lipkin-Meshkov-Glick model has been
discussed extensively in this paper. Measured by the global entanglement and
its generalization, our calculation shows that the multiparticle entanglement
can faithfully detect quantum phase transitions. For an antiferromagnetic case
the multiparticle entanglement reaches the maximum at the transition point,
whereas for ferromagnetic coupling, two different behaviors of multiparticle
entanglement can be identified, dependent on the anisotropic parameter in the
coupling.Comment: 7 pages and 5 figure
TimeClave: Oblivious In-enclave Time series Processing System
Cloud platforms are widely adopted by many systems, such as time series
processing systems, to store and process massive amounts of sensitive time
series data. Unfortunately, several incidents have shown that cloud platforms
are vulnerable to internal and external attacks that lead to critical data
breaches. Adopting cryptographic protocols such as homomorphic encryption and
secure multi-party computation adds high computational and network overhead to
query operations.
We present TimeClave, a fully oblivious in-enclave time series processing
system: TimeClave leverages Intel SGX to support aggregate statistics on time
series with minimal memory consumption inside the enclave. To hide the access
pattern inside the enclave, we introduce a non-blocking read-optimised ORAM
named RoORAM. TimeClave integrates RoORAM to obliviously and securely handle
client queries with high performance. With an aggregation time interval of
, summarised data blocks and 8 aggregate functions, TimeClave run
point query in and a range query of 50 intervals in . Compared
to the ORAM baseline, TimeClave achieves lower query latency by up to
and up to throughput, with up to 22K queries per second.Comment: The short version of this paper has been accepted as a Full Paper in
the International Conference on Information and Communications Security
(ICICS) 202
Shot noise of inelastic tunneling through quantum dot systems
We present a theoretical analysis of the effect of inelastic electron
scattering on current and its fluctuations in a mesoscopic quantum dot (QD)
connected to two leads, based on a recently developed nonperturbative technique
involving the approximate mapping of the many-body electron-phonon coupling
problem onto a multichannel single-electron scattering problem. In this, we
apply the B\"uttiker scattering theory of shot noise for a two-terminal
mesoscopic device to the multichannel case with differing weight factors and
examine zero-frequency shot noise for two special cases: (i) a single-molecule
QD and (ii) coupled semiconductor QDs. The nonequilibrium Green's function
method facilitates calculation of single-electron transmission and reflection
amplitudes for inelastic processes under nonequilibrium conditions in the
mapping model. For the single-molecule QD we find that, in the presence of the
electron-phonon interaction, both differential conductance and differential
shot noise display additional peaks as bias-voltage increases due to
phonon-assisted processes. In the case of coupled QDs, our nonperturbative
calculations account for the electron-phonon interaction on an equal footing
with couplings to the leads, as well as the coupling between the two dots. Our
results exhibit oscillations in both the current and shot noise as functions of
the energy difference between the two QDs, resulting from the spontaneous
emission of phonons in the nonlinear transport process. In the "zero-phonon"
resonant tunneling regime, the shot noise exhibits a double peak, while in the
"one-phonon" region, only a single peak appears.Comment: 10 pages, 6 figures, some minor changes, accepted by Phys. Rev.
Enhancement of Transition Temperature in FexSe0.5Te0.5 Film via Iron Vacancies
The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8<x<1) on
superconductivity and electronic properties have been studied. A significant
enhancement of the superconducting transition temperature (TC) up to 21K was
observed in the most Fe deficient film (x=0.8). Based on the observed and
simulated structural variation results, there is a high possibility that Fe
vacancies can be formed in the FexSe0.5Te0.5 films. The enhancement of TC shows
a strong relationship with the lattice strain effect induced by Fe vacancies.
Importantly, the presence of Fe vacancies alters the charge carrier population
by introducing electron charge carriers, with the Fe deficient film showing
more metallic behavior than the defect-free film. Our study provides a means to
enhance the superconductivity and tune the charge carriers via Fe vacancy, with
no reliance on chemical doping.Comment: 15 pages, 4 figure
Impact of elevated precipitation, nitrogen deposition and warming on soil respiration in a temperate desert
Abstract. Soil respiration (Rs) is the most important source of carbon
dioxide emissions from soil to atmosphere. However, it is unclear what the
interactive response of Rs would be to environmental changes such
as elevated precipitation, nitrogen (N) deposition and warming, especially in
unique temperate desert ecosystems. To investigate this an in situ field
experiment was conducted in the Gurbantunggut Desert, northwest China, from
September 2014 to October 2016. The results showed that precipitation and N
deposition significantly increased Rs, but warming decreased
Rs, except in extreme precipitation events, which was mainly
through its impact on the variation of soil moisture at 5 cm depth. In
addition, the interactive response of Rs to combinations of the
factors was much less than that of any single-factor, and the main response
was a positive effect, except for the response from the interaction of
increased precipitation and high N deposition
(60 kg N ha−1 yr−1). Although Rs was found to show
a unimodal change pattern with the variation of soil moisture, soil
temperature and soil NH4+-N content, and it was significantly
positively correlated to soil dissolved organic carbon (DOC) and pH, a
structural equation model found that soil temperature was the most important
controlling factor. Those results indicated that Rs was mainly
interactively controlled by the soil multi-environmental factors and soil
nutrients, and was very sensitive to elevated precipitation, N deposition and
warming. However, the interactions of multiple factors largely reduced
between-year variation of Rs more than any single-factor,
suggesting that the carbon cycle in temperate deserts could be profoundly
influenced by positive carbon–climate feedback.
</jats:p
Multipotent stem cells with neural crest stem cells characteristics exist in bovine adipose tissue
Neural crest stem cells (NCSCs) often referred to as the fourth germ layer, comprise a migratory, stem and progenitor cell population and are synonymous with vertebrate evolution and development. The cells follow specific paths to migrate to different locations of the body where they generate a diverse array of cell types and tissues. There are NCSCs which are maintained in an undifferentiated state throughout the life in the animal tissues. Based on some cells migratory property, we successfully developed a separation strategy to isolate and identify a population of adipose-derived stem cells with neural crest stem cell features in adult bovine adipose tissues within minimally-invasive surgical procedures. The cells have a high degree of multi-potency and self-renewal capabilities, can be cultured and maintained in feeder-free adhesion conditions as monolayer cells, and also be able to grow in the suspension condition in the form of neurosphere. For the purpose of simple description, we name this type cell as bovine adipose-derived neural crest stem cell (baNCSC). Taken together our study describes a readily accessible source of multipotent baNCSC for autologous tissue engineer and cell-based therapeutic researches
- …