24,478 research outputs found
Can only flavor-nonsinglet H dibaryons be stable against strong decays?
Using the QCD sum rule approach, we show that the flavor-nonsinglet
dibaryon states with J, J, I=1 (27plet) are nearly
degenerate with the J, I=0 singlet dibaryon, which has been
predicted to be stable against strong decay, but has not been observed. Our
calculation, which does not require an instanton correction, suggests that the
is slightly heavier than these flavor-nonsinglet s over a wide range
of the parameter space. If the singlet mass lies above the threshold (2231~MeV), then the strong interaction breakup to would produce a very broad resonance in the
invariant mass spectrum which would be very difficult to observe. On the other
hand, if these flavor-nonsinglet J=0 and 1 dibaryons are also above the
threshold, but below the breakup threshold (2254
MeV), then because the direct, strong interaction decay to the channel is forbidden, these flavor-nonsinglet states might be more
amenable to experimental observation. The present results allow a possible
reconciliation between the reported observation of
hypernuclei, which argue against a stable , and the possible existence of
dibaryons in general.Comment: 10 pages, 2 figure
The Pairing Mechanism in HTSC investigated by Electronic Raman Scattering
By means of electronic Raman scattering we investigated the symmetry of the
energy gap Delta(k), its temperature dependence and its variation with doping
of well characterized Bi2Sr2CaCu2O8+delta single crystals. The oxygen content
delta was varied between the under- and the overdoped regime by subsequently
annealing the same single crystal in Ar and O2, respectively. The symmetry
analysis of the polarized electronic Raman scattering is consistent with a
d_x^2-y^2-wave symmetry of the energy gap in both regimes. The gap ratio
2Delta_max/k_BT_c and its temperature dependence changes with doping similar to
predictions of theories based on paramagnon coupling.Comment: 3 pages, LaTeX, 2 ps figures available on request to
[email protected]
Human phosphodiesterase 4D7 (PDE4D7) expression is increased in TMPRSS2-ERG positive primary prostate cancer and independently adds to a reduced risk of post-surgical disease progression
background: There is an acute need to uncover biomarkers that reflect the molecular pathologies, underpinning prostate cancer progression and poor patient outcome. We have previously demonstrated that in prostate cancer cell lines PDE4D7 is downregulated in advanced cases of the disease. To investigate further the prognostic power of PDE4D7 expression during prostate cancer progression and assess how downregulation of this PDE isoform may affect disease outcome, we have examined PDE4D7 expression in physiologically relevant primary human samples.
methods: About 1405 patient samples across 8 publically available qPCR, Affymetrix Exon 1.0 ST arrays and RNA sequencing data sets were screened for PDE4D7 expression. The TMPRSS2-ERG gene rearrangement status of patient samples was determined by transformation of the exon array and RNA seq expression data to robust z-scores followed by the application of a threshold >3 to define a positive TMPRSS2-ERG gene fusion event in a tumour sample.
results: We demonstrate that PDE4D7 expression positively correlates with primary tumour development. We also show a positive association with the highly prostate cancer-specific gene rearrangement between TMPRSS2 and the ETS transcription factor family member ERG. In addition, we find that in primary TMPRSS2-ERG-positive tumours PDE4D7 expression is significantly positively correlated with low-grade disease and a reduced likelihood of progression after primary treatment. Conversely, PDE4D7 transcript levels become significantly decreased in castration resistant prostate cancer (CRPC).
conclusions: We further characterise and add physiological relevance to PDE4D7 as a novel marker that is associated with the development and progression of prostate tumours. We propose that the assessment of PDE4D7 levels may provide a novel, independent predictor of post-surgical disease progression
A novel technique for selective NF-kappa B inhibition in Kupffer cells: contrary effects in fulminant hepatitis and ischaemia-reperfusion.
Background and aims: The transcription factor nuclear
factor kappa B (NF-kB) has risen as a promising target for
anti-inflammatory therapeutics. In the liver, however, NFkB
inhibition mediates both damaging and protective
effects. The outcome is deemed to depend on the liver
cell type addressed. Recent gene knock-out studies
focused on the role of NF-kB in hepatocytes, whereas the
role of NF-kB in Kupffer cells has not yet been
investigated in vivo. Here we present a novel approach,
which may be suitable for clinical application, to
selectively target NF-kB in Kupffer cells and analyse the
effects in experimental models of liver injury.
Methods: NF-kB inhibiting decoy oligodeoxynucleotides
were loaded upon gelatin nanoparticles (D-NPs) and their
in vivo distribution was determined by confocal microscopy.
Liver damage, NF-kB activity, cytokine levels and
apoptotic protein expression were evaluated after
lipopolysaccharide (LPS), D-galactosamine (GalN)/LPS, or
concanavalin A (ConA) challenge and partial warm
ischaemia and subsequent reperfusion, respectively.
Results: D-NPs were selectively taken up by Kupffer cells
and inhibited NF-kB activation. Inhibition of NF-kB in
Kupffer cells improved survival and reduced liver injury
after GalN/LPS as well as after ConA challenge. While
anti-apoptotic protein expression in liver tissue was not
reduced, pro-apoptotic players such as cJun N-terminal
kinase (JNK) were inhibited. In contrast, selective
inhibition of NF-kB augmented reperfusion injury.
Conclusions: NF-kB inhibiting decoy oligodeoxynucleotide-
loaded gelatin nanoparticles is a novel tool to
selectively inhibit NF-kB activation in Kupffer cells in vivo.
Thus, liver injury can be reduced in experimental fulminant
hepatitis, but increased at ischaemia–reperfusion
Running coupling and mass anomalous dimension of SU(3) gauge theory with two flavors of symmetric-representation fermions
We have measured the running coupling constant of SU(3) gauge theory coupled
to Nf=2 flavors of symmetric representation fermions, using the Schrodinger
functional scheme. Our lattice action is defined with hypercubic smeared links
which, along with the larger lattice sizes, bring us closer to the continuum
limit than in our previous study. We observe that the coupling runs more slowly
than predicted by asymptotic freedom, but we are unable to observe fixed point
behavior before encountering a first order transition to a strong coupling
phase. This indicates that the infrared fixed point found with the thin-link
action is a lattice artifact. The slow running of the gauge coupling permits an
accurate determination of the mass anomalous dimension for this theory, which
we observe to be small, gamma_m < 0.6, over the range of couplings we can
reach. We also study the bulk and finite-temperature phase transitions in the
strong coupling region.Comment: 17 pages, 16 figures. Substantial modifications to explain why the
fat-link result for the beta function supersedes our thin-link result; also
updated the phase diagram to reflect additional numerical work. Added
references. Final versio
Optical spin pumping of modulation doped electrons probed by a two-color Kerr rotation technique
We report on optical spin pumping of modulation electrons in CdTe-based
quantum wells with low intrinsic electron density (by 10^10 cm^{-2}). Under
continuous wave excitation, we reach a steady state accumulated spin density of
about 10^8 cm^{-2}. Using a two-color Hanle-MOKE technique, we find a spin
relaxation time of 34 ns for the localized electrons in the nearly unperturbed
electron gas. Independent variation of the pump and probe energies demonstrates
the presence of additional non-localized electrons in the quantum well, whose
spin relaxation time is substantially shorter
Effective Conformal Theory and the Flat-Space Limit of AdS
We develop the idea of an effective conformal theory describing the low-lying
spectrum of the dilatation operator in a CFT. Such an effective theory is
useful when the spectrum contains a hierarchy in the dimension of operators,
and a small parameter whose role is similar to that of 1/N in a large N gauge
theory. These criteria insure that there is a regime where the dilatation
operator is modified perturbatively. Global AdS is the natural framework for
perturbations of the dilatation operator respecting conformal invariance, much
as Minkowski space naturally describes Lorentz invariant perturbations of the
Hamiltonian. Assuming that the lowest-dimension single-trace operator is a
scalar, O, we consider the anomalous dimensions, gamma(n,l), of the
double-trace operators of the form O (del^2)^n (del)^l O. Purely from the CFT
we find that perturbative unitarity places a bound on these dimensions of
|gamma(n,l)|<4. Non-renormalizable AdS interactions lead to violations of the
bound at large values of n. We also consider the case that these interactions
are generated by integrating out a heavy scalar field in AdS. We show that the
presence of the heavy field "unitarizes" the growth in the anomalous
dimensions, and leads to a resonance-like behavior in gamma(n,l) when n is
close to the dimension of the CFT operator dual to the heavy field. Finally, we
demonstrate that bulk flat-space S-matrix elements can be extracted from the
large n behavior of the anomalous dimensions. This leads to a direct connection
between the spectrum of anomalous dimensions in d-dimensional CFTs and
flat-space S-matrix elements in d+1 dimensions. We comment on the emergence of
flat-space locality from the CFT perspective.Comment: 46 pages, 2 figures. v2: JHEP published versio
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