Li-8 Magnetic Dipole-Moment

Polarized 8Li nuclei recoiling from the reaction 7Li(d, p)8Li were implanted in Au, Pd, and Pt foils, and the Knight-shifted values of the 8Li magnetic dipole moment in these metals were measured by a resonant depolarization technique. From measurements of the spinlattice relaxation times of 8Li implanted in Au, Pd, and Pt, the Knight shifts of 8Li in these metals were estimated. A corrected value for the magnetic dipole moment of 8Li was found to be μ(8Li)=(1.653 35±0.000 35)μN. Attempts were also made to measure the quadrupole couplings of 8Li in single crystals of Be and Mg. While the resonance lines could not be distinctly resolved, upper and lower limits have been deduced for |e2qQ/h| in these two metals

Framing the Discourse, Advancing the Work: Philanthropy at the Nexus of Peace and Social Justice and Arts andCulture

Framing the Discourse, Advancing the Work Philanthropy at the Nexus of Peace and Social Justice and Arts andCulture is based on Moukhtar Kocache's research and his experience in this field of work; and information gathered through interviews with artists, cultural producers and philanthropy practitioners; and in a convening held in August 2013 in Ontario, Canada.It presents an overview of the relationship between progressive social change work and the arts, explores the role of philanthropy in supporting this work and sets out recommendations for how philanthropy might further its engagement with work at this nexus. The objective of the report is to stimulate further reflection and exchange of lessons and opportunities for inculcating practices in philanthropy for supporting arts and culture work as a means to advance social justice and peace.The process of compiling this report has been a journey and, like all journeys, it has involved changes of perspective and, like some journeys, a revision of ideas. During its course, it has become clear to us that arts and culture are not just a matter of better tools for supporting change; they are often central to personal and social transformation. The arts often reach us -- and influence us - in ways that direct explanation cannot. The call to philanthropy that seeks to support progressive social change is to recognise this transformational power of arts and culture and to engage with it as a holistic strategy.This argument will be presented more extensively in a brief paper (to be published in August 2014) entitled, 'Making the Case for the Arts to Social Justice Funders'

Quadrupole Couplings of N12 and B12 Implanted in Metal Single-Crystals

Measurements have been made of the quadrupole couplings of 12N implanted in single crystals of Be and Mg and of 12B implanted in a single crystal of Zn. A comparison of the 12N couplings in Be and Mg suggests that (i) the final stopping sites of the implanted 12N ions are substitutional sites, i.e., the 12N ions occupy metal-ion lattice positions, and (ii) the 12N ions implanted in Be and Mg have the same charge state and quadrupole shielding factor. A procedure is outlined for deducing Q(12N). The 12B couplings in Zn imply the existence of two inequivalent stopping sites. The problems encountered in deducing Q(12B) from couplings in metal hexagonal crystals are discussed

Measurement of Nuclear Magnetic Dipole Moment of Li-8 by Implantation in Metal Foils

Polarized 8Li nuclei have been produced through the 7Li(d,p) reaction using the 3.5-MeV Van de Graaff accelerator at Brookhaven National Laboratory. The observed polarization was a slowly-varying function of deuteron energy over the range 1.3-2.9 MeV, reaching a maximum of about +1.6%. The recoiling nuclei were stopped in Au, Pt and Pd foils and the effective dipole moments were measured by a resonant depolarization method. The results were 1.65362(22)µN, 1.65288(20)µN and 1.65270(30)µN respectively. These are consistent with the work of Connor, who found µ(8Li) =1.6530(8)µN in a LiF crystal. An upper limit for the 8Li quadrupole moment will also be discussed

Study of Stopping Sites of B12 Nuclei Implanted in Hexagonal Single-Crystals

A series of experiments to study the stopping sites of 12B nuclei implanted in single crystals of Be and Mg will be discussed. Previous measurements of the quadrupole couplings of 12B in these metals indicated that two different stopping sites existed, one of which produced a negligible quadrupole coupling

Observation of Quadrupole Splitting of B-12 in a Single Crystal

The quadrupole coupling of B-12 implanted in Be-9 has been observed using a single crystal of Be. One sees a narrow resonance line, the location of which depends in the normal way on the orientation of the crystalline c-axis with respect to the external magnetic field direction. The coupling constant is given by e2qQ/h = 54.9(6) kHz. This is consistent with our previous measurement using a Be foil. Using the field gradient at Be-9 lattice sites, calculated by Pomerantz and Das, one finds Q(B-12) = about 34.6 mb

Nuclear Quadrupole Coupling of B-12 in a Single Be Crystal

Quadrupole resonance lines of β-unstable 12B have been distinctly resolved in a single crystal of Be, and have behaved properly under field reversal and variation of the angle θ between crystal c axis and external magnetic field

Statistical Estimation Procedures for the ''burn-in'' Process

Statistical estimation procedures for identifying and eliminating poor quality or defective item

Finite-Size Scaling in the Energy-Entropy Plane for the 2D +- J Ising Spin Glass

For $L \times L$ square lattices with $L \le 20$ the 2D Ising spin glass with +1 and -1 bonds is found to have a strong correlation between the energy and the entropy of its ground states. A fit to the data gives the result that each additional broken bond in the ground state of a particular sample of random bonds increases the ground state degeneracy by approximately a factor of 10/3. For $x = 0.5$ (where $x$ is the fraction of negative bonds), over this range of $L$, the characteristic entropy defined by the energy-entropy correlation scales with size as $L^{1.78(2)}$. Anomalous scaling is not found for the characteristic energy, which essentially scales as $L^2$. When $x= 0.25$, a crossover to $L^2$ scaling of the entropy is seen near $L = 12$. The results found here suggest a natural mechanism for the unusual behavior of the low temperature specific heat of this model, and illustrate the dangers of extrapolating from small $L$.Comment: 9 pages, two-column format; to appear in J. Statistical Physic

Maximum a posteriori estimation for Markov chains based on Gaussian Markov random fields

In this paper, we present a Gaussian Markov random field (GMRF) model for the transition matrices (TMs) of Markov chains (MCs) by assuming the existence of a neighborhood relationship between states, and develop the maximum a posteriori (MAP) estimators under different observation conditions. Unlike earlier work on TM estimation, our method can make full use of the similarity between different states to improve the estimated accuracy, and the estimator can be performed very efficiently by solving a convex programming problem. In addition, we discuss the parameter choice of the proposed model, and introduce a Monte Carlo cross validation (MCCV) method. The numerical simulations of a diffusion process are employed to show the effectiveness of the proposed models and algorithms