981 research outputs found
Immigrants and Homeownership in Urban America: An Examination of Nativity, Socio-economic Status and Place
A unique pilot project conducted in America's small and medium-sized cities shows that broad-based community coalitions can proactively integrate the newcomers who are increasingly transforming Main St., USA. In the first project of its kind, a consortium of leading organizations in three mid-sized metropolitan areas undertook inclusive community-building. The project's final report contains valuable findings for policymakers, funders and organizations collectively approaching the challenge of helping newcomers adapt to their new communities and local communities welcome newcomers
Adiabatic fission barriers in superheavy nuclei
Using the microscopic-macroscopic model based on the deformed Woods-Saxon
single-particle potential and the Yukawa-plus-exponential macroscopic energy we
calculated static fission barriers for 1305 heavy and superheavy nuclei
, including even - even, odd - even, even - odd and odd -
odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces
were calculated by a minimization over configurations with one blocked neutron
or/and proton on a level from the 10-th below to the 10-th above the Fermi
level. The parameters of the model that have been fixed previously by a fit to
masses of even-even heavy nuclei were kept unchanged. A search for saddle
points has been performed by the "Imaginary Water Flow" method on a basic
five-dimensional deformation grid, including triaxiality. Two auxiliary grids
were used for checking the effects of the mass asymmetry and hexadecapole
non-axiallity. The ground states were found by energy minimization over
configurations and deformations. We find that the non-axiallity significantly
changes first and second fission barrier in many nuclei. The effect of the mass
- asymmetry, known to lower the second, very deformed barriers in actinides, in
the heaviest nuclei appears at the less deformed saddles in more than 100
nuclei. It happens for those saddles in which the triaxiallity does not play
any role, what suggests a decoupling between effects of the mass-asymmetry and
triaxiality. We studied also the influence of the pairing interaction strength
on the staggering of for odd- and even-particle numbers. Finally, we
provide a comparison of our results with other theoretical fission barrier
evaluations and with available experimental estimates.Comment: submitted to PR
Superdeformed Oblate Superheavy Nuclei?
We study stability of superdeformed oblate (SDO) superheavy
nuclei predicted by systematic macroscopic-microscopic calculations in 12D
deformation space and confirmed by the Hartree-Fock calculations with the
realistic SLy6 force. We include into consideration high- isomers that very
likely form at the SDO shape. Although half-lives s
are calclulated or estimated for even-even spin zero systems, decay hindrances
known for high- isomers suggest that some SDO superheavy nuclei may be
detectable by the present experimental technique.Comment: 4 pages, 5 figure
Effect of oxygen plasma on nanomechanical silicon nitride resonators
Precise control of tensile stress and intrinsic damping is crucial for the
optimal design of nanomechanical systems for sensor applications and quantum
optomechanics in particular. In this letter we study the in uence of oxygen
plasma on the tensile stress and intrinsic damping of nanomechanical silicon
nitride resonators. Oxygen plasma treatments are common steps in micro and
nanofabrication. We show that oxygen plasma of only a few minutes oxidizes the
silicon nitride surface, creating several nanometer thick silicon dioxide
layers with a compressive stress of 1.30(16)GPa. Such oxide layers can cause a
reduction of the e ective tensile stress of a 50 nm thick stoichiometric
silicon nitride membrane by almost 50%. Additionally, intrinsic damping
linearly increases with the silicon dioxide lm thickness. An oxide layer of
1.5nm grown in just 10s in a 50W oxygen plasma almost doubled the intrinsic
damping. The oxide surface layer can be e ciently removed in bu ered HF
UBQLN4 Represses Homologous Recombination and Is Overexpressed in Aggressive Tumors
Genomic instability can be a hallmark of both human genetic disease and cancer. We identify a deleterious UBQLN4 mutation in families with an autosomal recessive syndrome reminiscent of genome instability disorders. UBQLN4 deficiency leads to increased sensitivity to genotoxic stress and delayed DNA double-strand break (DSB) repair. The proteasomal shuttle factor UBQLN4 is phosphorylated by ATM and interacts with ubiquitylated MRE11 to mediate early steps of homologous recombination-mediated DSB repair (HRR). Loss of UBQLN4 leads to chromatin retention of MRE11, promoting non-physiological HRR activity in vitro and in vivo. Conversely, UBQLN4 overexpression represses HRR and favors non-homologous end joining. Moreover, we find UBQLN4 overexpressed in aggressive tumors. In line with an HRR defect in these tumors, UBQLN4 overexpression is associated with PARP1 inhibitor sensitivity. UBQLN4 therefore curtails HRR activity through removal of MRE11 from damaged chromatin and thus offers a therapeutic window for PARP1 inhibitor treatment in UBQLN4-overexpressing tumors
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