882 research outputs found
Enhanced Orbital Degeneracy in Momentum Space for LaOFeAs
The Fermi surfaces (FS) of LaOFeAs (in =0 plane) consist of two
hole-type circles around point, which do not touch each other, and two
electron-type co-centered ellipses around M point, which are degenerate along
the M-X line. By first-principles calculations, here we show that additional
degeneracy exists for the two electron-type FS, and the crucial role of
F-doping and pressure is to enhance this orbital degeneracy. It is suggested
that the inter-orbital fluctuation is the key point to understand the
unconventional superconductivity in these materials.Comment: 4 pages, 5 figure
Darboux Transformations for a Lax Integrable System in -Dimensions
A -dimensional Lax integrable system is proposed by a set of specific
spectral problems. It contains Takasaki equations, the self-dual Yang-Mills
equations and its integrable hierarchy as examples. An explicit formulation of
Darboux transformations is established for this Lax integrable system. The
Vandermonde and generalized Cauchy determinant formulas lead to a description
for deriving explicit solutions and thus some rational and analytic solutions
are obtained.Comment: Latex, 14 pages, to be published in Lett. Math. Phy
Sociodemographic and obstetric characteristics of stillbirths in China: a census of nearly 4 million health facility births between 2012 and 2014
Background Very little is known about the burden and determinants of stillbirths in China. We used data from a
national surveillance system for health facility births to compute a stillbirth rate representative of all facility births in
China and to explore sociodemographic and obstetric factors associated with variation in the stillbirth rate.
Methods We used data from China’s National Maternal Near Miss Surveillance System between Jan 1, 2012, and
Dec 31, 2014, which covers 441 hospitals in 326 urban districts and rural counties. The surveillance aimed to
enumerate all maternal deaths and near misses in health facilities, and collected data prospectively for all pregnant
or post-partum women admitted to the obstetric department. We restricted the analysis to births of 28 or more
completed weeks of gestation or 1000 g or heavier birthweight. We examined the strength of association between
sociodemographic characteristics, gestational age, and obstetric complications and stillbirths using logistic
regression, taking account of the sampling strategy and clustering of births within hospitals and in cases of more
than one birth per woman.
Findings There were 3 956 836 births and 37 855 stillbirths, giving a stillbirth rate of 8·8 per 1000 births (95% CI
8·8–8·9). The stillbirth rate was particularly high for women younger than 15 years of age (59·9 stillbirths
per 1000 births), those who had not sought antenatal care (38·3 per 1000), the unmarried (32·5 per 1000), those with
no education (26·9 per 1000), or those who had had four or more births (23·2 per 1000). A high proportion
(29 319 [78·2%] of 37 514) of stillbirths occurred at gestational ages of younger than 37 weeks, and about two thirds
(24 787 [66·1%] of 37 514) were in women without any maternal complication at the time of birth. Of babies born at
normal gestations (37–41 weeks), maternal complications substantially increased the risk of stillbirth (odds ratio
comparing antepartum or intrapartum complications with no complication 3·96 [95% CI 3·66–4·29]), but only a
small proportion (1638 [4·4%] of 37 514) of stillbirths fell into this group.
Interpretation Our analysis of nearly 4 million births in 441 health facilities in China suggests a stillbirth rate of
8·8 per 1000 births between 2012 and 2014. Stillbirths do not feature in the Chinese Government’s 5 year plans and
most information systems do not include stillbirths. The Government need to start paying attention to stillbirths and
invest strategically in antenatal care, particularly for the most disadvantaged women, including the very young,
unmarried, and illiterate, and those at high parity
Differential expression and functions of Ehm2 transcript variants in lung adenocarcinoma
Ehm2 [also known as erythrocyte membrane protein band 4.1‑like protein 4B (EPB41L4B)] is a member of the NF2/ERM/4.1 superfamily. The overexpression of Ehm2 has been observed in metastatic cancer cells. Through alternative splicing, the Ehm2 gene produces two transcript variants that encode the two different isoforms, Ehm2/1 and Ehm2/2. The biological functions of these different Ehm2 transcript variants remain unclear. The present study aimed to determine the expression of the Ehm2 variants in lung adenocarcinoma and their involvement in the disease progression of the patients. The expression of Ehm2 transcript variants in human lung adenocarcinoma tissues was analyzed using immunohistochemistry and western blot analysis. Ehm2 variants were overexpressed or knocked down in A549 human lung adenocarcinoma cells. The consequent effects of the genetic modifications on the cellular functions of lung cancer cells were then examined using in vitro cell viability, invasion and migration assays. The expression of epithelial‑mesenchymal transition (EMT)‑related markers was evaluated by western blot analysis in the cell models. The association of Ehm2 variant expression with patient survival was analyzed using Kaplan‑Meier survival analysis. The expression of Ehm2/1 was significantly decreased in lung cancers compared with the paired normal lung tissues (P<0.05), while the Ehm2/2 protein levels were higher in the tumors than in the paired normal lung tissues, although this was not statistically significant. The overexpression of Ehm2/1 exerted inhibitory effects, while the knockdown of Ehm2/1 promoted the growth, invasion and migration of A549 cells in vitro. Ehm2/2 was expressed at low levels in the A549 cells and the enforced expression of Ehm2/2 significantly increased the invasiveness and migration of the A549 cells. Immunofluorescence staining revealed that Ehm2/1 was confined to the plasma membrane, while Ehm2/2 was observed at both the plasma membrane and cytoplasm. The overexpression of Ehm2/1 resulted in the upregulation of the epithelial marker, E‑cadherin, and in the decreased expression of the mesenchymal markers, N‑cadherin and Snail1, while the knockdown of Ehm2/1 and the enforced expression of Ehm2/2 had the opposite effects on the protein levels of EMT‑related markers. Kaplan‑Meier survival analysis revealed that higher Ehm2/1 transcript levels were associated with the longer survival of patients with lung adenocarcinoma, while the lower expression of Ehm2/2 exhibited a similar association with patient survival. Taken together, the two Ehm2 variants appear to be differentially expressed in lung adenocarcinoma. Ehm2/1 may function as a putative tumor suppressor in the disease progression of lung adenocarcinoma, while Ehm2/2 may have an opposite function
Competitions of magnetism and superconductivity in FeAs-based materials
Using the numerical unrestricted Hartree-Fock approach, we study the ground
state of a two-orbital model describing newly discovered FeAs-based
superconductors. We observe the competition of a mode spin-density
wave and the superconductivity as the doping concentration changes. There might
be a small region in the electron-doping side where the magnetism and
superconductivity coexist. The superconducting pairing is found to be spin
singlet, orbital even, and mixed s + d wave (even
parity).Comment: 5 pages, 3 figure
Nematic orders in Iron-based superconductors
In the newly discovered iron-based superconductors, many experiments have
demonstrated the existence of the rotational symmetry breaking nematic order,
which has been a prevailing phenomenon in many correlated electronic systems.
In this paper, we review nematic behaviors in iron-pnictides and the mechanism
behind the development of the nematic order. We discuss evidences that support
the spin-driven nematicity in iron-pnictides. Theories, results and predictions
will be discussed based on this picture. We also briefly discuss the
generalization of this theory to the nematicity in iron-chalcogenides.Comment: Invited review article for special issue "Stripes and Electronic
Liquid Crystals in Strongly Correlated Systems" of Physica C; Review article
for Special Issue of Physica C: "Stripes and Electronic Liquid Crystals in
Strongly Correlated Systems", 201
Prevalence of intestinal trichomonads in captive non-human primates in China
Trichomonads are protozoan symbionts with the capacity to infect vertebrates including humans and non-human primates (NHPs), sometimes with pathogenic effects. However, their diversity and prevalence in NHPs in China are poorly understood. A total of 533 fecal samples were collected from captive NHPs in Yunnan Province, China, of which 461 samples from Macaca fascicularis and 72 from Macaca mulatta. Trichomonadidae species were identified using PCR amplification of the ITS-1/5.8S/ITS-2 sequences. The overall prevalence of trichomonads in NHPs was determined to be 11.4% (61/533), with gender, diarrhea, and region identified as potential risk factors for the infections. Sequence alignment and phylogenetic analysis identified three species of trichomonads, i.e., Trichomitopsis minor (n = 45), Pentatrichomonas hominis (n = 11), and Tetratrichomonas sp. (n = 5). To the best of our knowledge, this is the first study to report Trichomitopsis minor infection in NHPs in China. Of note, Pentatrichomonas hominis is generally recognized as a parasitic organism affecting humans. Collectively, our results suggest that NHPs are potential sources of zoonotic trichomonad infections, highlighting the importance of surveillance and control measures to protect human and animal populations
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