620 research outputs found
Generation linewidth of an auto-oscillator with a nonlinear frequency shift: Spin-torque nano-oscillator
It is shown that the generation linewidth of an auto-oscillator with a
nonlinear frequency shift (i.e. an auto-oscillator in which frequency depends
on the oscillation amplitude) is substantially larger than the linewidth of a
conventional quasi-linear auto-oscillator due to the renormalization of the
phase noise caused by the nonlinearity of the oscillation frequency. The
developed theory, when applied to a spin-torque nano-contact auto-oscillator,
predicts a minimum of the generation linewidth when the nano-contact is
magnetized at a critical angle to its plane, corresponding to the minimum
nonlinear frequency shift, in good agreement with recent experiments.Comment: 4 pages, 2 figure
Study Of Oxidation Processes In Duck Meat With Application Of Rosemary And Grape Seed Extracts
The substantiation of the expedience of using antioxidants of a natural origin to decelerate oxidation processes in different meat products is an urgent direction of these studies. The prospective way of a solution of the problem of meat products oxidation spoilage is the use of vegetable extracts. The experimental studies of the effective use of the composition of rosemary and grape seed extracts in Peking duck forcemeat at the long storage were realized. Their influence on the dynamics of hydrolytic and peroxide oxidation of forcemeat lipids was studied. The analysis of oxidation secondary products accumulation was realized at the same time.The positive effect of the combined use of rosemary and grape seeds extracts on frozen Peking duck forcemeat was established, the optimal concentration of offered preparations was determined
Optimizing data collection for public health decisions: a data mining approach
Background: Collecting data can be cumbersome and expensive. Lack of relevant, accurate and timely data for research to inform policy may negatively impact public health. The aim of this study was to test if the careful removal of items from two community nutrition surveys guided by a data mining technique called feature selection, can (a) identify a reduced dataset, while (b) not damaging the signal inside that data.
Methods: The Nutrition Environment Measures Surveys for stores (NEMS-S) and restaurants (NEMS-R) were completed on 885 retail food outlets in two counties in West Virginia between May and November of 2011. A reduced dataset was identified for each outlet type using feature selection. Coefficients from linear regression modeling were used to weight items in the reduced datasets. Weighted item values were summed with the error term to compute reduced item survey scores. Scores produced by the full survey were compared to the reduced item scores using a Wilcoxon rank-sum test.
Results: Feature selection identified 9 store and 16 restaurant survey items as significant predictors of the score produced from the full survey. The linear regression models built from the reduced feature sets had R2 values of 92% and 94% for restaurant and grocery store data, respectively.
Conclusions: While there are many potentially important variables in any domain, the most useful set may only be a small subset. The use of feature selection in the initial phase of data collection to identify the most influential variables may be a useful tool to greatly reduce the amount of data needed thereby reducing cost
Noise properties of a resonance-type spin-torque microwave detector
We analyze performance of a resonance-type spin-torque microwave detector
(STMD) in the presence of noise and reveal two distinct regimes of STMD
operation. In the first (high-frequency) regime the minimum detectable
microwave power is limited by the low-frequency Johnson-Nyquist
noise and the signal-to-noise ratio (SNR) of STMD is proportional to the input
microwave power . In the second (low-frequency) regime is limited by the magnetic noise, and the SNR is proportional to
. The developed formalism can be used for the optimization
of the practical noise-handling parameters of a STMD.Comment: 3 pages, 2 figure
Parametric resonance of magnetization excited by electric field
Manipulation of magnetization by electric field is a central goal of
spintronics because it enables energy-efficient operation of spin-based
devices. Spin wave devices are promising candidates for low-power information
processing but a method for energy-efficient excitation of short-wavelength
spin waves has been lacking. Here we show that spin waves in nanoscale magnetic
tunnel junctions can be generated via parametric resonance induced by electric
field. Parametric excitation of magnetization is a versatile method of
short-wavelength spin wave generation, and thus our results pave the way
towards energy-efficient nanomagnonic devices
Pattern formation during electrodeposition of copper-antimony alloys
Aim of the present study is to establish the conditions of the electrolysis for the preparation of structured and unstressed purple-pink coatings of copper-antimony alloys, including their phase characterization. Also the task of the present investigation is, by changing drastically the metal content in the methanesulfonic electrolyte to find out the conditions of electrolysis where the self-organization of the different phases is expressed by higher-order structures - not only waves but also spirals and targets. The possibility to obtain copper-antimony alloy with up to 80 wt. % Sb from methanesulfonic acid is shown. The deposition rate, morphology and the phase composition of the obtained coatings are established. The phenomena of formation of spatio-temporal structures in this alloy are described.It is determined that the observed structures consist of Cu2Sb and Cu11Sb3 intermetallic phases
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