339 research outputs found
The Dual Meissner Effect and Magnetic Displacement Currents
The dual Meissner effect is observed without monopoles in quenched
QCD with Landau gauge-fixing. Magnetic displacement currents which are
time-dependent Abelian magnetic fields play a role of solenoidal currents
squeezing Abelian electric fields. Monopoles are not always necessary to the
dual Meissner effect. The squeezing of the electric flux means the dual London
equation and the massiveness of the Abelian electric fields as an asymptotic
field. The mass generation of the Abelian electric fields is related to a gluon
condensate of mass dimension 2.Comment: 4 pages, 5 Postscript figures, title modified, some references added,
minor changes made ; Accepted for publication in Phys.Rev.Let
Abelian dominance and the dual Meissner effect in local unitary gauges in SU(2) gluodynamics
Performing highly precise Monte-Carlo simulations of SU(2) gluodynamics, we
observe for the first time Abelian dominance in the confining part of the
static potential in local unitary gauges such as the F12 gauge. We also study
the flux-tube profile between the quark and antiquark in these local unitary
gauges and find a clear signal of the dual Meissner effect. The Abelian
electric field is found to be squeezed into a flux tube by the monopole
supercurrent. This feature is the same as that observed in the non-local
maximally Abelian gauge. These results suggest that the Abelian confinement
scenario is gauge independent. Observing the important role of space-like
monopoles in the Polyakov gauge also indicates that the monopoles defined on
the lattice do not necessarily correspond to those proposed by 't Hooft in the
context of Abelian projection.Comment: 4 pages, 7 figure
Testicular somatic cell-like cells derived from embryonic stem cells induce differentiation of epiblasts into germ cells
Regeneration of the testis from pluripotent stem cells is a real challenge, reflecting the complexity of the interaction of germ cells and somatic cells. Here we report the generation of testicular somatic cell-like cells (TesLCs) including Sertoli cell-like cells (SCLCs) from mouse embryonic stem cells (ESCs) in xeno-free culture. We find that Nr5a1/SF1 is critical for interaction between SCLCs and PGCLCs. Intriguingly, co-culture of TesLCs with epiblast-like cells (EpiLCs), rather than PGCLCs, results in self-organised aggregates, or testicular organoids. In the organoid, EpiLCs differentiate into PGCLCs or gonocyte-like cells that are enclosed within a seminiferous tubule-like structure composed of SCLCs. Furthermore, conditioned medium prepared from TesLCs has a robust inducible activity to differentiate EpiLCs into PGCLCs. Our results demonstrate conditions for in vitro reconstitution of a testicular environment from ESCs and provide further insights into the generation of sperm entirely in xeno-free culture
Vacuum type of SU(2) gluodynamics in maximally Abelian and Landau gauges
The vacuum type of SU(2) gluodynamics is studied using Monte-Carlo
simulations in maximally Abelian (MA) gauge and in Landau (LA) gauge, where the
dual Meissner effect is observed to work. The dual Meissner effect is
characterized by the coherence and the penetration lengths. Correlations
between Wilson loops and electric fields are evaluated in order to measure the
penetration length in both gauges. The coherence length is shown to be fixed in
the MA gauge from measurements of the monopole density around the static
quark-antiquark pair. It is also shown numerically that a dimension 2 gluon
operator A^+A^-(s) and the monopole density has a strong correlation as
suggested theoretically. Such a correlation is observed also between the
monopole density and A^2(s)= A^+A^-(s) + A^3A^3(s) condensate if the remaining
U(1) gauge degree of freedom is fixed to U(1) Landau gauge (U1LA). The
coherence length is determined numerically also from correlations between
Wilson loops and A^+A^-(s) and A^2(s) in MA + U1LA gauge. Assuming that the
same physics works in the LA gauge, we determine the coherence length from
correlations between Wilson loops and A^2(s). Penetration lengths and coherence
lengths in the two gauges are almost the same. The vacuum type of the
confinement phase in both gauges is near to the border between the type 1 and
the type 2 dual superconductors.Comment: 13 pages, 22 figures, RevTeX 4 styl
Venus Express radio occultation observed by PRIDE
Context. Radio occultation is a technique used to study planetary atmospheres
by means of the refraction and absorption of a spacecraft carrier signal
through the atmosphere of the celestial body of interest, as detected from a
ground station on Earth. This technique is usually employed by the deep space
tracking and communication facilities (e.g., NASA's Deep Space Network (DSN),
ESA's Estrack). Aims. We want to characterize the capabilities of the Planetary
Radio Interferometry and Doppler Experiment (PRIDE) technique for radio
occultation experiments, using radio telescopes equipped with Very Long
Baseline Interferometry (VLBI) instrumentation. Methods. We conducted a test
with ESA's Venus Express (VEX), to evaluate the performance of the PRIDE
technique for this particular application. We explain in detail the data
processing pipeline of radio occultation experiments with PRIDE, based on the
collection of so-called open-loop Doppler data with VLBI stations, and perform
an error propagation analysis of the technique. Results. With the VEX test case
and the corresponding error analysis, we have demonstrated that the PRIDE setup
and processing pipeline is suited for radio occultation experiments of
planetary bodies. The noise budget of the open-loop Doppler data collected with
PRIDE indicated that the uncertainties in the derived density and temperature
profiles remain within the range of uncertainties reported in previous Venus'
studies. Open-loop Doppler data can probe deeper layers of thick atmospheres,
such as that of Venus, when compared to closed-loop Doppler data. Furthermore,
PRIDE through the VLBI networks around the world, provides a wide coverage and
range of large antenna dishes, that can be used for this type of experiments
PRELP secreted from mural cells protects the function of blood brain barrier through regulation of endothelial cell-cell integrity
INTRODUCTION:
Proline/arginine-rich end leucine-rich repeat protein (PRELP), is a small secreted proteoglycan expressed by pericytes and vascular smooth muscle cells surrounding the brain vasculature of adult mouse.
METHODS:
We utilised a Prelp knockout (Prelp−/−) mouse model to interrogate vasculature integrity in the brain alongside performing in vitro assays to characterise PRELP application to endothelial cells lines. Our findings were supplemented with RNA expression profiling to elucidate the mechanism of how PRELP maintains neurovasculature function.
RESULTS:
Prelp−/− mice presented with neuroinflammation and reducedneurovasculature integrity, resulting in IgG and dextran leakage in the cerebellum and cortex. Histological analysis of Prelp−/− mice revealed reducedcell-cell integrity of the blood brain barrier, capillary attachment of pericytes andastrocyte end-feet. RNA-sequencing analysis found that cell-cell adhesion andinflammation are affected in Prelp−/− mice and gene ontology analysis as well as gene set enrichment analysis demonstrated that inflammation related processes and adhesion related processes such as epithelial-mesenchymal transition and apical junctions were significantly affected, suggesting PRELP is a regulator of cell-cell adhesion. Immunofluorescence analysis showed that adhesion junction protein expression levels of cadherin, claudin-5, and ZO-1, was suppressed in Prelp−/− mice neurovasculature. Additionally, in vitro studies revealed that PRELP application to endothelial cells enhances cell-cell integrity, induces mesenchymal-endothelial transition and inhibits TGF-β mediated damage to cell-cell adhesion.
DISCUSSION:
Our study indicates that PRELP is a novel endogenous secreted regulator of neurovasculature integrity and that PRELP application may be a potential treatment for diseases associated with neurovascular damage
Aldose reductase gene is associated with diabetic macroangiopathy in Japanese Type 2 diabetic patients
AIMS: The aldose reductase (AR) gene, a rate-limiting enzyme of the polyol pathway, has been investigated as a candidate gene in determining susceptibility to diabetic microangiopathy. However, the association of the AR gene with diabetic macroangiopathy has not been investigated. Therefore, the present study was conducted to determine whether genetic variations of AR may determine susceptibility to diabetic macroangiopathy. METHODS: There were 378 Type 2 diabetic patients enrolled in this study. A single nucleotide polymorphism in the promoter region (C-106T) was genotyped and the AR protein content of erythrocytes measured by ELISA. RESULTS: There were no significant differences in genotypic or allelic distribution in patients with or without ischaemic heart diseases, but there was a significant increase in the frequency of the CT + TT genotype and T allele in patients with stroke (P = 0.019 and P = 0.012). The erythrocyte AR protein content was increased in patients with the CT and TT genotype compared with those with the CC genotype. After adjustment for age, duration of diabetes, body mass index, systolic blood pressure, HbA(1c), and serum creatinine, triglycerides, and total cholesterol in multivariate logistic-regression models, the association between this AR genotype and stroke remained significant. CONCLUSIONS: Our results suggest that the CT or TT genotype of the AR gene might be a genetic marker of susceptibility to stroke in Type 2 diabetic patients. This observation might contribute to the development of strategies for the prevention of stroke in Type 2 diabetic patients
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