11,896 research outputs found
Effect of Antiferromagnetic Interlayer Coupling on Current-Assisted Magnetization Switching
We compare magnetization switching in Co/Cu/Co nanopillars with uncoupled and
dipole-field coupled Co layers. In uncoupled nanopillars, current-driven
switching is hysteretic at low magnetic field H and changes to reversible,
characterized by telegraph noise, at high H. We show that dipolar coupling both
affects the switching current and causes the switching to become reversible at
small H. The coupling thus changes the switching to reversible, hysteretic, and
then reversible again as H increases. We describe our results in terms of
current-assisted thermal activation.Comment: 3 pages, 3 figure
Switching Current vs. Magnetoresistance in Magnetic Multilayer Nanopillars
We study current-driven magnetization switching in nanofabricated magnetic
trilayers, varying the magnetoresistance in three different ways. First, we
insert a strongly spin-scattering layer between the magnetic trilayer and one
of the electrodes, giving increased magnetoresistance. Second, we insert a
spacer with a short spin-diffusion length between the magnetic layers,
decreasing the magnetoresistance. Third, we vary the angle between layer
magnetizations. In all cases, we find an approximately linear dependence
between magnetoresistance and inverse switching current. We give a qualitative
explanation for the observed behaviors, and suggest some ways in which the
switching currents may be reduced.Comment: 3 pages, 4 figure
Comment on "Canonical and Mircocanonical Calculations for Fermi Systems"
In the context of nuclear physics Pratt recently investigated noninteracting
Fermi systems described by the microcanonical and canonical ensemble. As will
be shown his discussion of the model of equally spaced levels contains a flaw
and a statement which is at least confusing.Comment: Comment on S. Pratt, Phys. Rev. Lett. 84, 4255 (2000) and
nucl-th/990505
The phase transition in the localized ferromagnet EuO probed by muSR
We report results of muon spin rotation measurements performed on the
ferromagnetic semiconductor EuO, which is one of the best approximations to a
localized ferromagnet. We argue that implanted muons are sensitive to the
internal field primarily through a combination of hyperfine and Lorentz fields.
The temperature dependences of the internal field and the relaxation rate have
been measured and are compared with previous theoretical predictions.Comment: 4 pages, 4 figure
Chromosome 9p deletion in clear cell renal cell carcinoma predicts recurrence and survival following surgery
BACKGROUND: Wider clinical applications of 9p status in clear cell renal cell carcinoma (ccRCC) are limited owing to the lack of validation and consensus for interphase fluorescent in situ hybridisation (I-FISH) scoring technique. The aim of this study was to analytically validate the applicability of I-FISH in assessing 9p deletion in ccRCC and to clinically assess its long-term prognostic impact following surgical excision of ccRCC. METHODS: Tissue microarrays were constructed from 108 renal cell carcinoma (RCC) tumour paraffin blocks. Interphase fluorescent in situ hybridisation analysis was undertaken based on preset criteria by two independent observers to assess interobserver variability. 9p status in ccRCC tumours was determined and correlated to clinicopathological variables, recurrence-free survival and disease-specific survival. RESULTS: There were 80 ccRCCs with valid 9p scoring and a median follow-up of 95 months. Kappa statistic for interobserver variability was 0.71 (good agreement). 9p deletion was detected in 44% of ccRCCs. 9p loss was associated with higher stage, larger tumours, necrosis, microvascular and renal vein invasion, and higher SSIGN (stage, size, grade and necrosis) score. Patients with 9p-deleted ccRCC were at a higher risk of recurrence (P=0.008) and RCC-specific mortality (P=0.001). On multivariate analysis, 9p deletion was an independent predictor of recurrence (hazard ratio 4.323; P=0.021) and RCC-specific mortality (hazard ratio 4.603; P=0.007). The predictive accuracy of SSIGN score improved from 87.7% to 93.1% by integrating 9p status to the model (P=0.001). CONCLUSIONS: Loss of 9p is associated with aggressive ccRCC and worse prognosis in patients following surgery. Our findings independently confirm the findings of previous reports relying on I-FISH to detect 9p (CDKN2A) deletion
Current-Driven Magnetic Excitations in Permalloy-Based Multilayer Nanopillars
We study current-driven magnetization switching in nanofabricated
Ni84Fe16/Cu/Ni84Fe16 trilayers at 295 K and 4.2 K. The shape of the hysteretic
switching diagram at low magnetic field changes from 295 K to 4.2 K. The
reversible behavior at higher field involves two phenomena, a threshold current
for magnetic excitations closely correlated with the switching current, and a
peak in differential resistance characterized by telegraph noise, with average
period that decreases exponentially with current and shifts with temperature.
We interpret both static and dynamic results at 295 K and 4.2 K in terms of
thermal activation over a potential barrier, with a current dependent effective
magnetic temperature.Comment: 4 pages, 4 Figure
A system of relational syllogistic incorporating full Boolean reasoning
We present a system of relational syllogistic, based on classical
propositional logic, having primitives of the following form:
Some A are R-related to some B;
Some A are R-related to all B;
All A are R-related to some B;
All A are R-related to all B.
Such primitives formalize sentences from natural language like `All students
read some textbooks'. Here A and B denote arbitrary sets (of objects), and R
denotes an arbitrary binary relation between objects. The language of the logic
contains only variables denoting sets, determining the class of set terms, and
variables denoting binary relations between objects, determining the class of
relational terms. Both classes of terms are closed under the standard Boolean
operations. The set of relational terms is also closed under taking the
converse of a relation. The results of the paper are the completeness theorem
with respect to the intended semantics and the computational complexity of the
satisfiability problem.Comment: Available at
http://link.springer.com/article/10.1007/s10849-012-9165-
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