4,081 research outputs found
Accelerating universe in two-dimensional noncommutative dilaton cosmology
We show that the phase transition from the decelerating universe to the
accelerating universe, which is of relevance to the cosmological coincidence
problem, is possible in the semiclassically quantized two-dimensional dilaton
gravity by taking into account the noncommutative field variables during the
finite time. Initially, the quantum-mechanically induced energy from the
noncommutativity among the fields makes the early universe decelerate and
subsequently the universe is accelerating because the dilaton driven cosmology
becomes dominant later.Comment: 14 pages, 2 figures; to appear in Phys. Lett.
Dihydropyrimidine-thiones and clioquinol synergize to target beta-amyloid cellular pathologies through a metal-dependent mechanism
The lack of therapies for neurodegenerative diseases arises from our incomplete understanding of their underlying cellular toxicities and the limited number of predictive model systems. It is critical that we develop approaches to identify novel targets and lead compounds. Here, a phenotypic screen of yeast proteinopathy models identified dihydropyrimidine-thiones (DHPM-thiones) that selectively rescued the toxicity caused by β-amyloid (Aβ), the peptide implicated in Alzheimer’s disease. Rescue of Aβ toxicity by DHPM-thiones occurred through a metal-dependent mechanism of action. The bioactivity was distinct, however, from that of the 8-hydroxyquinoline clioquinol (CQ). These structurally dissimilar compounds strongly synergized at concentrations otherwise not competent to reduce toxicity. Cotreatment ameliorated Aβ toxicity by reducing Aβ levels and restoring functional vesicle trafficking. Notably, these low doses significantly reduced deleterious off-target effects caused by CQ on mitochondria at higher concentrations. Both single and combinatorial treatments also reduced death of neurons expressing Aβ in a nematode, indicating that DHPM-thiones target a conserved protective mechanism. Furthermore, this conserved activity suggests that expression of the Aβ peptide causes similar cellular pathologies from yeast to neurons. Our identification of a new cytoprotective scaffold that requires metal-binding underscores the critical role of metal phenomenology in mediating Aβ toxicity. Additionally, our findings demonstrate the valuable potential of synergistic compounds to enhance on-target activities, while mitigating deleterious off-target effects. The identification and prosecution of synergistic compounds could prove useful for developing AD therapeutics where combination therapies may be required to antagonize diverse pathologies.D.F.T was funded by NRSA Fellowship NIH 5F32NS061419. D.F.T. and S.L. were supported by WIBR funds in support of research on Regenerative Disease, the Picower/JPB Foundation, and the Edward N. and Della L. Thome Foundation. G.A.C. and S.L. were funded by a Howard Hughes Medical Institute (HHMI) Collaborative Innovation Award. L.E.B., R.T., and S.E.S. were funded by NIH GM086180, NIH GM067041, and NIH GM111625. (5F32NS061419 - NRSA Fellowship NIH; WIBR funds in support of research on Regenerative Disease; Picower/JPB Foundation; Edward N. and Della L. Thome Foundation; Howard Hughes Medical Institute (HHMI) Collaborative Innovation Award; GM086180 - NIH; NIH GM067041 - NIH; NIH GM111625 - NIH)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5705239/Accepted manuscrip
A Quintessential Axion
The model independent axion of string theory has a decay constant of order of
the Planck scale. We explore the properties of this quintessence candidate
(quintaxion) in the scheme of hidden sector supergravity breakdown. In models
allowing for a reasonable term, the hidden sector dynamics may lead to an
almost flat potential responsible for the vacuum energy of . A solution to the strong CP-problem is provided by an additional
hidden sector pseudoscalar (QCD axion) with properties that make it an
acceptable candidate for cold dark matter of the universe.Comment: 11 pages, Revtex, 1 figur
Interacting holographic generalized Chaplygin gas model
In this paper we consider a correspondence between the holographic dark
energy density and interacting generalized Chaplygin gas energy density in FRW
universe. Then we reconstruct the potential of the scalar field which describe
the generalized Chaplygin cosmology.Comment: 12 pages, no figur
Neutrino Oscillations and Lepton Flavor Mixing
In view of the recent announcement on non-zero neutrino mass from
Super-Kamiokande experiment, it would be very timely to investigate all the
possible scenarios on masses and mixings of light neutrinos. Recently suggested
mass matrix texture for the quark CKM mixing, which can be originated from the
family permutation symmetry and its suitable breakings, is assumed for the
neutrino mass matrix and determined by the four combinations of solar,
atmospheric and LSND neutrino data and cosmological hot dark matter bound as
input constraints. The charged-lepton mass matrix is assumed to be diagonal so
that the neutrino mixing matrix can be identified directly as the lepton flavor
mixing matrix and no CP invariance violation originates from the leptonic
sector. The results favor hierarchical patterns for the neutrino masses, which
follow from the case when either solar-atmospheric data or solar-HDM
constraints are used.Comment: Latex, 9 page
AWAKE-related benchmarking tests for simulation codes
Two tests are described that were developed for benchmarking and comparison
of numerical codes in the context of AWAKE experiment.Comment: 4 pages, 4 figures, 1 tabl
Dark energy, inflation and the cosmic coincidence problem
We show that holographic dark energy could explain why the current dark
energy density is so small, if there was an inflation with a sufficient
expansion in the early universe. It is also suggested that an inflation with
the number of e-folds may solve the cosmic coincidence problem in
this context. Assuming the inflation and the power-law acceleration phase today
we obtain approximate formulas for the event horizon size of the universe and
dark energy density as functions of time. A simple numerical study exploiting
the formula well reproduces the observed evolution of dark energy. This
nontrivial match between the theory and the observational data supports both
inflation and holographic dark energy models.Comment: final versio
Phantom Wormholes in (2+1)-dimensions
In this paper, we have constructed a (2+1)-dimensional wormhole using
inhomogeneous and anisotropic distribution of phantom energy. We have
determined the exact form of the equation of state of phantom energy that
supports the wormhole structure. Interestingly, this equation of state is
linear but variable one and is dependent only on the radial parameter of the
model.Comment: 10 pages, 5 figure
- …