3,690 research outputs found
Human Leukocyte Antigen Testing: Technology Versus Policy in Cases of Disputed Parentage
This Note assumes that the judicial trend of using HLA test results as affirmative evidence will continue, and accepts the proposal that these results are scientifically reliable.\u27 The Note will focus on the policy considerations and arguments that should affect the admissibility of the HLA blood test as affirmative evidence in various disputed parentage cases.This Note first examines the use of HLA test results to determine the paternity of illegitimate children who do not have a legal father, and concludes that courts should admit the results unconditionally in these circumstances. Second, the Note analyzes the use of the HLA blood test to settle paternity disputes that arise in a divorce context. Because of the important policy considerations that exist, the Note recommends that courts admit the results subject to a legislatively developed statute of limitations of two or three years. Finally, the Note advocates that public policy factors indicate the need for a two-year statute of limitations to govern the admissibility of HLA test results in situations in which an unmarried father attempts to introduce them to assert paternity rights concerning a presumably legitimate child who has a legal father
Anharmonicity and self-energy effects of the E2g phonon in MgB2
We present a Raman scattering study of the E2g phonon anharmonicity and of
superconductivity induced self-energy effects in MgB2 single crystals. We show
that anharmonic two phonon decay is mainly responsible for the unusually large
linewidth of the E2g mode. We observe ~ 2.5 % hardening of the E2g phonon
frequency upon cooling into the superconducting state and estimate the
electron-phonon coupling strength associated with this renormalization.Comment: 4 pages, 3 figures, accepted to PR
Magnetic order in lightly doped La_{2-x}Sr_{x}CuO_{4}
We study long wavelength magnetic excitations in lightly doped
La_{2-x}Sr_{x}CuO_{4} (x < 0.03) detwinned crystals. The lowest energy magnetic
anisotropy induced gap can be understood in terms of the antisymmetric spin
interaction inside the antiferromagnetic (AF) phase. The second magnetic
resonace, analyzed in terms of in-plane spin anisotropy, shows unconventional
behavior within the AF state and led to the discovery of collective spin
excitations pertaining to a field induced magnetically ordered state. This
state persists in a 9 T field to more than 100 K above the N\'{e}el temperature
in x = 0.01.Comment: 5 pages, 5 figure
Resonant Two-Magnon Raman Scattering and Photoexcited States in Two-Dimensional Mott Insulators
We investigate the resonant two-magnon Raman scattering in two-dimensional
(2D) Mott insulators by using a half-filled 2D Hubbard model in the strong
coupling limit. By performing numerical diagonalization calculations for small
clusters, we find that the Raman intensity is enhanced when the incoming photon
energy is not near the optical absorption edge but well above it, being
consistent with experimental data. The absence of resonance near the gap edge
is associated with the presence of background spins, while photoexcited states
for resonance are found to be characterized by the charge degree of freedom.
The resonance mechanism is different from those proposed previously.Comment: REVTeX4, 4 pages, 3 figures, to be published in Phys. Rev. Let
Inhomogeneous CuO_{6} Tilt Distribution and Charge/Spin Correlations in La_{2-x-y}Nd_{y}Sr_{x}CuO$_{4} around commensurate hole concentration
Phononic and magnetic Raman scattering are studied in
LaNdSrCuO with three doping concentrations: x ~
1/8, y = 0; x ~ 1/8, y = 0.4; and x = 0.01, y = 0. We observe strong disorder
in the tilt pattern of the CuO_{6} octahedra in both the orthorhombic and
tetragonal phases which persist down to 10 K and are coupled to bond disorder
in the cation layers around 1/8 doping independent of Nd concentration. The
weak magnitude of existing charge/spin modulations in the Nd doped structure
does not allow us to detect the specific Raman signatures on lattice dynamics
or two-magnon scattering around 2200 cm-1.Comment: to be published in Phys. Rev.
Sliding Density-Wave in Sr_{14}Cu_{24}O_{41} Ladder Compounds
We used transport and Raman scattering measurements to identify the
insulating state of self-doped spin 1/2 two-leg ladders of Sr_{14}Cu_{24}O_{41}
as a weakly pinned, sliding density wave with non-linear conductivity and a
giant dielectric response that persists to remarkably high temperatures
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