1,797 research outputs found
Planar spin exchange in LiNiO_2
We study the planar spin exchange couplings in LiNiO2 using a perturbative
approach. We show that the inclusion of the trigonal crystal field splitting at
the Oxygen sites leads to the appearance of antiferromagnetic exchange
integrals in deviation from the Goodenough-Kanamori-Anderson rules for this 90
degree bond. That gives a microscopic foundation for the recently observed
coexistence of ferromagnetic and antiferromagnetic couplings in the
orbitally-frustrated state of LiNiO2. (F. Reynaud et al, Phys. Rev. Lett. 86,
3638 (2001))Comment: latex, revtex4, 6 pages, 3 figure
Scaling of Traction Forces with Size of Cohesive Cell Colonies
To understand how the mechanical properties of tissues emerge from
interactions of multiple cells, we measure traction stresses of cohesive
colonies of 1-27 cells adherent to soft substrates. We find that traction
stresses are generally localized at the periphery of the colony and the total
traction force scales with the colony radius. For large colony sizes, the
scaling appears to approach linear, suggesting the emergence of an apparent
surface tension of order 1E-3 N/m. A simple model of the cell colony as a
contractile elastic medium coupled to the substrate captures the spatial
distribution of traction forces and the scaling of traction forces with the
colony size.Comment: 5 pages, 3 figure
The effects of exposure to a rotating environment /10 rpm/ on four aviators for a period of twelve days
Motion sickness studies of aviators exposed to rotating environment - Aerospace medicin
A Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron
Recoil proton polarization observables were measured for both the p(,e) and d(,en reactions at two values of Q using a newly commissioned proton
Focal Plane Polarimeter at the M.I.T.-Bates Linear Accelerator Center. The
hydrogen and deuterium spin-dependent observables and
, the induced polarization and the form factor ratio
were measured under identical kinematics. The deuterium and
hydrogen results are in good agreement with each other and with the plane-wave
impulse approximation (PWIA).Comment: 9 pages, 1 figure; accepted by Phys. Rev. Let
Noise-reduction in the nondegenerate parametric oscillator with direct detection feedback
A quantum analysis of the above-threshold intensity fluctuations in a nondegenerate parametric oscillator with direct-detection feedback onto the pump amplitude is presented. We derive a master equation for the signal (in-loop) and idler (out-of-loop) modes by adiabatically eliminating the pump mode and incorporating a feedback term, using the Wiseman-Milburn quantum feedback theroy [Phys. Rev. Lett. 70, 548 (1993)]. In the absence of feedback and far above threshold, we find that both beams are 50% intensity squeezed. For small negative (positive) feedback, the intensity fluctuations in the out-of-loop (in-loop) beam are reduced further. For larger values of feedback, the fluctuations grow, the fields eventually becoming unsqueezed
A theory-based approach to understanding condom errors and problems reported by men attending an STI clinic
The official published version can be accessed from the link below - Copyright @ 2008 Springer VerlagWe employed the information–motivation–behavioral skills (IMB) model to guide an investigation of correlates for correct condom use among 278 adult (18–35 years old) male clients attending a sexually transmitted infection (STI) clinic. An anonymous questionnaire aided by a CD-recording of the questions was administered. Linear Structural Relations Program was used to conduct path analyses of the hypothesized IMB model. Parameter estimates showed that while information did not directly affect behavioral skills, it did have a direct (negative) effect on condom use errors. Motivation had a significant direct (positive) effect on behavioral skills and a significant indirect (positive) effect on condom use errors through behavioral skills. Behavioral skills had a direct (negative) effect on condom use errors. Among men attending a public STI clinic, these findings suggest brief, clinic-based, safer sex programs for men who have sex with women should incorporate activities to convey correct condom use information, instill motivation to use condoms correctly, and directly enhance men’s behavioral skills for correct use of condoms
Instruments of RT-2 Experiment onboard CORONAS-PHOTON and their test and evaluation III: Coded Aperture Mask and Fresnel Zone Plates in RT-2/CZT Payload
Imaging in hard X-rays of any astrophysical source with high angular
resolution is a challenging job. Shadow-casting technique is one of the most
viable options for imaging in hard X-rays. We have used two different types of
shadow-casters, namely, Coded Aperture Mask (CAM) and Fresnel Zone Plate (FZP)
pair and two types of pixellated solid-state detectors, namely, CZT and CMOS in
RT-2/CZT payload, the hard X-ray imaging instrument onboard the CORONAS-PHOTON
satellite. In this paper, we present the results of simulations with different
combinations of coders (CAM & FZP) and detectors that are employed in the
RT-2/CZT payload. We discuss the possibility of detecting transient Solar
flares with good angular resolution for various combinations. Simulated results
are compared with laboratory experiments to verify the consistency of the
designed configuration.Comment: 27 pages, 16 figures, Accepted for publication in Experimental
Astronomy (in press
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