1,141 research outputs found
Constraint Generation Algorithm for the Minimum Connectivity Inference Problem
Given a hypergraph , the Minimum Connectivity Inference problem asks for a
graph on the same vertex set as with the minimum number of edges such that
the subgraph induced by every hyperedge of is connected. This problem has
received a lot of attention these recent years, both from a theoretical and
practical perspective, leading to several implemented approximation, greedy and
heuristic algorithms. Concerning exact algorithms, only Mixed Integer Linear
Programming (MILP) formulations have been experimented, all representing
connectivity constraints by the means of graph flows. In this work, we
investigate the efficiency of a constraint generation algorithm, where we
iteratively add cut constraints to a simple ILP until a feasible (and optimal)
solution is found. It turns out that our method is faster than the previous
best flow-based MILP algorithm on random generated instances, which suggests
that a constraint generation approach might be also useful for other
optimization problems dealing with connectivity constraints. At last, we
present the results of an enumeration algorithm for the problem.Comment: 16 pages, 4 tables, 1 figur
S_3 Flavor Symmetry and Leptogenesis
We consider leptogenesis in a minimal
S_3 extension of the standard model with an additional Z_2 symmetry in the
leptonic sector. It is found that the CP phase appearing in the neutrino mixing
is the same as that for the CP asymmetries responsible for leptogenesis.
Because of the discrete S_3 x Z_2 flavor symmetries, the CP asymmetries are
strongly suppressed. We therefore assume that the resonant enhancement of the
CP asymmetries takes place to obtain a realistic size of baryon number
asymmetry in theuniverse. Three degenerate right-handed neutrino masses of
O(10) TeV are theoretically expected in this model.Comment: 25 pages, 3 figure
Homodinuclear Lanthanide Complexes with the Divergent Heterotopic 4,4′-Bipyridine N-Oxide (bipyMO) Ligand
The synthesis of dinuclear molecular complexes [Eu2(dbm)6(bipyMO)2], 1, [Tb2(dbm)6(bipyMO)2], 2, [Eu2(tta)6(bipyMO)2], 3 [Eu2(hfac)6(bipyMO)3], 4, [Tb2(hfac)6(bipyMO)3], 5 is here reported (bipyMO = 4,4′-bipyridine N-oxide, Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone). The products were obtained in mild conditions and with high yields reacting anhydrous lanthanide β-diketonates and bipyMO in 1:1 or 1.5 molar ratio in toluene. X-ray single crystal studies on 2, 3, 4 showed that the heterotopic ligands are hypodentate, bridging the two lanthanide centres exclusively through the oxygen atom. Photoluminescence studies show bright red emissions from europium derivatives with absolute quantum yields up to 44 %
TeV Scale Leptogenesis, theta_13 And Doubly Charged Particles At LHC
We explore a realistic supersymmetric SU(2)_L \times SU(2)_R \times U(1)_B-L
model spontaneously broken at around 10^12 GeV. The presence of D and F-flat
directions gives rise to TeV mass doubly charged particles which can be found
at the LHC. We implement TeV scale leptogenesis and employing both type I and
II seesaw, the three light neutrinos are partially degenerate with masses in
the 0.02-0.1 eV range. The effective mass parameter for neutrinoless double
beta decay is 0.03-0.05 eV. We also find the interesting relation tan 2
\theta_13 ~ [\Delta m^2_{\odot} / \Delta m^2_{atm}] [sin 2 \theta_12 /tan 2
\theta_23] <~ 0.02.Comment: 18 pages, 4 figures, revtex4. v2: minor changes, matches published
versio
Leptogenesis in Minimal Left-Right Symmetric Models
We analyze lepton asymmetry induced in the decay of right--handed neutrinos
in a class of minimal left--right symmetric models. In these models, which
assume low energy supersymmetry, the Dirac neutrino mass matrix is proportional
to the charged lepton mass matrix. As a result, lepton asymmetry is calculable
in terms of 9 parameters, all measurable in low energy neutrino experiments. By
solving the Boltzmann equations numerically we show that adequate baryon
asymmetry is generated in these models. This however places significant
constraints on the light neutrino parameters. We find tan^2\theta_{12} =
m_1/m_2 and \theta_{13} = (0.01 - 0.07) for the neutrino oscillation angles,
and \beta = \alpha + \pi/2 for the Majorana phases.Comment: 25 pages, 3 eps figures, references adde
The novel CXCR4 antagonist POL5551 mobilizes hematopoietic stem and progenitor cells with greater efficiency than Plerixafor
Mobilized blood has supplanted bone marrow (BM) as the primary source of hematopoietic stem cells for autologous and allogeneic stem cell transplantation. Pharmacologically enforced egress of hematopoietic stem cells from BM, or mobilization, has been achieved by directly or indirectly targeting the CXCL12/CXCR4 axis. Shortcomings of the standard mobilizing agent, granulocyte colony-stimulating factor (G-CSF), administered alone or in combination with the only approved CXCR4 antagonist, Plerixafor, continue to fuel the quest for new mobilizing agents. Using Protein Epitope Mimetics technology, a novel peptidic CXCR4 antagonist, POL5551, was developed. In vitro data presented herein indicate high affinity to and specificity for CXCR4. POL5551 exhibited rapid mobilization kinetics and unprecedented efficiency in C57BL/6 mice, exceeding that of Plerixafor and at higher doses also of G-CSF. POL5551-mobilized stem cells demonstrated adequate transplantation properties. In contrast to G-CSF, POL5551 did not induce major morphological changes in the BM of mice. Moreover, we provide evidence of direct POL5551 binding to hematopoietic stem and progenitor cells (HSPCs) in vivo, strengthening the hypothesis that CXCR4 antagonists mediate mobilization by direct targeting of HSPCs. In summary, POL5551 is a potent mobilizing agent for HSPCs in mice with promising therapeutic potential if these data can be orroborated in humans
Development of a reactive stroma associated with prostatic intraepithelial neoplasia in EAF2 deficient mice
ELL-associated factor 2 (EAF2) is an androgen-responsive tumor suppressor frequently deleted in advanced prostate cancer that functions as a transcription elongation factor of RNA Pol II through interaction with the ELL family proteins. EAF2 knockout mice on a 129P2/OLA-C57BL/6J background developed late-onset lung adenocarcinoma, hepatocellular carcinoma, B-cell lymphoma and high-grade prostatic intraepithelial neoplasia. In order to further characterize the role of EAF2 in the development of prostatic defects, the effects of EAF2 loss were compared in different murine strains. In the current study, aged EAF2-/- mice on both the C57BL/6J and FVB/NJ backgrounds exhibited mPIN lesions as previously reported on a 129P2/OLA-C57BL/6J background. In contrast to the 129P2/OLA-C57BL/6J mixed genetic background, the mPIN lesions in C57BL/6J and FVB/NJ EAF2-/- mice were associated with stromal defects characteristic of a reactive stroma and a statistically significant increase in prostate microvessel density. Stromal inflammation and increased microvessel density was evident in EAF2-deficient mice on a pure C57BL/6J background at an early age and preceded the development of the histologic epithelial hyperplasia and neoplasia found in the prostates of older EAF2 -/- animals. Mice deficient in EAF2 had an increased recovery rate and a decreased overall response to the effects of androgen deprivation. EAF2 expression in human cancer was significantly down-regulated and microvessel density was significantly increased compared to matched normal prostate tissue; furthermore EAF2 expression was negatively correlated with microvessel density. These results suggest that the EAF2 knockout mouse on the C57BL/6J and FVB/NJ genetic backgrounds provides a model of PIN lesions associated with an altered prostate microvasculature and reactive stromal compartment corresponding to that reported in human prostate tumors. © 2013 Pascal et al
The Earth Regeneration Effect of Solar Neutrinos: a Numerical Treatment with Three Active Neutrino Flavors
We introduce an integrated algorithm for full scale investigation of the
earth regeneration effect of solar neutrinos with all three active neutrinos.
We illustrate that the earth effect on low energy solar neutrinos (
MeV) causes large variations in the survival probabilities for large values of
the mixing angle for a given value of . But it is
maximal for small values of and diminishes for large values at a
given value of . The nadir angle dependence is sensitive to the
value of . As far as low energy solar neutrinos are
concerned we notice that the earth effect is more pronounced for core
penetration. We confirm that the earth effect leaves the SMA region almost
intact regardless of and that it is significant for high energy
B and neutrinos in the LMA region. We also show that for large values
of , the earth effect is significant for high energy neutrinos
() and it can be large at any nadir angle.Comment: 8 pages, 2 postscript figure
Runoff Estimation and Morphometric Analysis for Hesaraghatta Watershed Using IRS–1D LISS III FCC Satellite Data
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