143 research outputs found
Loschmidt Echo and Berry phase of the quantum system coupled to the XY spin chain: Proximity to quantum phase transition
We study the Loschmidt echo (LE) of a coupled system consisting of a central
spin and its surrounding environment described by a general XY spin-chain
model. The quantum dynamics of the LE is shown to be remarkably influenced by
the quantum criticality of the spin chain. In particular, the decaying behavior
of the LE is found to be controlled by the anisotropy parameter of the spin
chain. Furthermore, we show that due to the coupling to the spin chain, the
ground-state Berry phase for the central spin becomes nonanalytical and its
derivative with respect to the magnetic parameter in spin chain
diverges along the critical line , which suggests an alternative
measurement of the quantum criticality of the spin chain.Comment: 15 pages, 5 figure
Improving mobility of silicon metal-oxide-semiconductor devices for quantum dots by high vacuum activation annealing
To improve mobility of fabricated silicon metal-oxide-semiconductor (MOS)
quantum devices, forming gas annealing is a common method used to mitigate the
effects of disorder at the Si/SiO2 interface. However, the importance of
activation annealing is usually ignored. Here, we show that a high vacuum
environment for implantation activation is beneficial for improving mobility
compared to nitrogen atmosphere. Low-temperature transport measurements of Hall
bars show that peak mobility can be improved by a factor of two, reaching 1.5
m^2/(Vs) using high vacuum annealing during implantation activation. Moreover,
the charge stability diagram of a single quantum dot is mapped, with no visible
disturbance caused by disorder, suggesting possibility of fabricating
high-quality quantum dots on commercial wafers. Our results may provide
valuable insights into device optimization in silicon-based quantum computing.Comment: 13 pages, 4 figure
Double Strangeness − Production as a Probe of Nuclear Equation of State at High Densities
Double strangeness production in Au+Au collisions at 2, 4, and 6
GeV/nucleon incident beam energies is studied with the pure hadron cascade
version of a multi-phase transport model. It is found that due to larger
nuclear compression, the model with the soft equation of state (EoS) gives
larger yields of both single strangeness ( and ) and
double strangeness . The sensitivity of the double strangeness
to the EoS is evidently larger than that of or
since the phase-space distribution of produced
is more compact compared to those of the single strangeness. The larger
sensitivity of the yields ratio of to the EoS from heavy and light
systems is kept compared to that of the single strangeness. The study of
production in relativistic heavy-ion collisions provides an
alternative for the ongoing heavy-ion collision program at facilities worldwide
for identifying the EoS at high densities, which is relevant to the
investigation of the phase boundary and onset of deconfinement of dense nuclear
matter.Comment: 5 pages, 5 figures, PLB, in productio
Case report: Tall cell carcinoma with reversed polarity of the breast: an additional case and review of the literature
ObjectiveThe aim of this report was to comprehensively investigate the clinicopathological features, histological characteristics, and differential diagnosis of tall cell carcinoma with reversed polarity of the breast (TCCRP) to enhance the understanding of this tumour for precise therapeutic interventions.MethodsThe clinicopathological characteristics and differential diagnosis of a patient with TCCRP were retrospectively analysed, and a systematic literature review was extracted from relevant published studies on PubMed.ResultsAll patients included in the study were female, with a median age of 51 years. Microscopically, the tumour cells exhibited a solid papillary growth pattern with tall columnar morphology and reversed nuclear polarity. Immunohistochemistry revealed that the tumours were triple-negative breast cancer (negative for ER, PR, and HER-2), with a low Ki-67 proliferation index. Different degrees of expression were observed for CK7, Calretinin, and S-100 markers; however, CK5/6 showed high expression levels.ConclusionsTCCRP is an uncommon invasive carcinoma subtype found in the breast. Its histological morphology resembles that of tall cell subtype papillary thyroid carcinoma. Accurate diagnosis requires the integration of histomorphological assessment along with immunohistochemistry and molecular genetics analysis
Seroprevalence of Toxoplasma gondii infection in pet dogs in Kunming, Southwest China
BACKGROUND: Toxoplasmosis is a zoonotic parasitic disease caused by the protozoan Toxoplasma gondii, which infects almost all warm-blooded animals, including humans, with a worldwide distribution. However, little is known of T. gondii seroprevalence in pet dogs in Kunming, the capital of Yunnan Province, southwest China. The objective of this investigation was to estimate the seroprevalence of T. gondii infection in pet dogs in this area. METHODS: A total of 611 serum samples were collected from 7 pet hospitals in Kunming, and assayed for T. gondii antibodies by the indirect haemagglutination (IHA) using a commercially-marked kit. RESULTS: 132 (21.6%) pet dogs were positive for T. gondii antibodies, and the seroprevalence ranged from 17.3% to 34.7% among different sampling regions, the difference was statistically significant (P < 0.05). The T. gondii seroprevalence in female and male dogs were 20.8% and 22.4%, respectively, the difference was not statistically significant (P > 0.05). The seroprevalence ranged from 17.5% to 23.6% among different age groups, but the difference was not statistically significant (P > 0.05), and there were no interactions in statistics (P > 0.05) between gender and age of pet dogs in the region. CONCLUSIONS: The findings of the present survey indicate high T. gondii seroprevalance in pet dogs in Kunming, southwest China, posing significant public health concern. It is necessary to enhance integrated strategies and measures to prevent and control T. gondii infection in pet dogs in this area
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