Neutron deformation inHo165

Abstract

We report asymmetries in the forward-angle difFerential cross sections for pion single-chargeexchange scattering from oriented and unoriented Ho nuclei. These asymmetries are directly related to the neutron deformation of a nucleus that has a large charge quadrupole moment. The measured asymmetry extrapolated to 0' is -0.020 6 0.024. In the model of Chiang and Johnson, this value implies a quadrupole deformation ratio P2/Pz = 0.84+0.08, indicating that the excess neutrons are less deformed than the protons. This result conSicts with the predictions of the best available Hartree-Fock models based on Skyrme interactions. We also report on asymmetries of the nonresonant continuum and of the giant dipole resonances.Elastic electron-scattering experiments provide the best systematic information on the nuclear shapes in that, to 6rst order, the momentum-transfer dependence of the cross sections is the Fourier transforxn of the charge distribution. Auxiliary information and constraints are also obtained kom inelastic-scattering experiments for which, within the &amework of vibrational or rotational models, the cross sections are proportional to the squares of the Pr, coefBcients. The quadrupole deformation moment Pz 0556-2813/94/50(2)/909

Vegetation trends over eleven years on mountain summits in NW Argentina

“…We used linear mixed models and generalized linear mixed models (LMM and GLMM; Bolker et al, 2009) to analyze variability in plant cover, species richness, and diversity index among aspects within summits, among summits, and among censuses, with aspect and census as fixed effects and summit as a random effect. For model construction, we considered Gaussian distribution for plant cover (square root transformed data) and Shannon index, using the package lme4 in R (Bates, Kliegl, Vasishth, & Baayen, 2015), and followed by lmerTest (Kuznetsova, Brockhoff, & Christensen, 2017), to obtain p values for fixed effects, and Poisson distribution for species richness using the package GLMM (Knudson, 2016).…”

“…During the period 2008 -2012, the area was influenced by the coupled oceanic -atmospheric event, El Niño Southern Oscillation (ENSO) -La Niña phase, manifested by higher precipitation at this elevation (Supporting Information Supporting Information Figure S1), like other subtropical and tropical high Andean areas (Carilla, Grau, Paolini, & Morales, 2013;Morales et al, 2015). On the contrary, El Niño phase is linked to dry periods at these elevations (e.g., El Niño 1997-98, 2003-04, 2015-2016Morales et al, 2015). ENSO oscillations are reflected in lake levels recorded off and on since 1926 (Halloy, 1985a(Halloy, , 2002Minetti, 2015).…”