RF amplification property of the MgO-based magnetic tunnel junction using field-induced ferromagnetic resonance

The radio-frequency (RF) voltage amplification property of a tunnel magnetoresistance device driven by an RF external-magnetic-field-induced ferromagnetic resonance was studied. The proposed device consists of a magnetic tunnel junction (MTJ) and an electrically isolated coplanar waveguide. The input RF voltage applied to the waveguide can excite the resonant dynamics in the free layer magnetization, leading to the generation of an output RF voltage under a DC bias current. The dependences of the RF voltage gain on the static external magnetic field strength and angle were systematically investigated. The design principles for the enhancement of the gain factor are also discussed.Comment: 12 pages, 3 figure

Quantum phase transition in quantum wires controlled by an external gate

We consider electrons in a quantum wire interacting via a long-range Coulomb potential screened by a nearby gate. We focus on the quantum phase transition from a strictly one-dimensional to a quasi-one-dimensional electron liquid, that is controlled by the dimensionless parameter $n x_0$, where $n$ is the electron density and $x_0$ is the characteristic length of the transverse confining potential. If this transition occurs in the low-density limit, it can be understood as the deformation of the one-dimensional Wigner crystal to a zigzag arrangement of the electrons described by an Ising order parameter. The critical properties are governed by the charge degrees of freedom and the spin sector remains essentially decoupled. At large densities, on the other hand, the transition is triggered by the filling of a second one-dimensional subband of transverse quantization. Electrons at the bottom of the second subband interact strongly due to the diverging density of states and become impenetrable. We argue that this stabilizes the electron liquid as it suppresses pair-tunneling processes between the subbands that would otherwise lead to an instability. However, the impenetrable electrons in the second band are screened by the excitations of the first subband, so that the transition is identified as a Lifshitz transition of impenetrable polarons. We discuss the resulting phase diagram as a function of $n x_0$.Comment: 18 pages, 8 figures, minor changes, published versio

Measurement of electron screening in muonic lead

Energies of the transitions between high-lying (n≥6) states of muonic lead were accurately determined. The results are interpreted as a ∼2% test of the electron screening. The agreement between experiment and theory is good if it is assumed that the refilling of the electron K shell is fast. The present results furthermore severely restrict possible ionization of the electron L shell

Adaptive Investment Strategies For Periodic Environments

In this paper, we present an adaptive investment strategy for environments with periodic returns on investment. In our approach, we consider an investment model where the agent decides at every time step the proportion of wealth to invest in a risky asset, keeping the rest of the budget in a risk-free asset. Every investment is evaluated in the market via a stylized return on investment function (RoI), which is modeled by a stochastic process with unknown periodicities and levels of noise. For comparison reasons, we present two reference strategies which represent the case of agents with zero-knowledge and complete-knowledge of the dynamics of the returns. We consider also an investment strategy based on technical analysis to forecast the next return by fitting a trend line to previous received returns. To account for the performance of the different strategies, we perform some computer experiments to calculate the average budget that can be obtained with them over a certain number of time steps. To assure for fair comparisons, we first tune the parameters of each strategy. Afterwards, we compare the performance of these strategies for RoIs with different periodicities and levels of noise.Comment: Paper submitted to Advances in Complex Systems (November, 2007) 22 pages, 9 figure

Computing welfare losses from data under imperfect competition with heterogeneous goods

We study the percentage of welfare losses (PWL) yielded by imperfect competition under product differentiation. When demand is linear, if prices, outputs, costs and the number of firms can be observed, PWL is arbitrary in both Cournot and Bertrand equilibria. If in addition, the elasticity of demand (resp. cross elasticity of demand) is known, we can calculate PWL in Cournot (resp. Bertrand) equilibrium. When demand is isoelastic and there are many firms, PWL can be computed from prices, outputs, costs and the number of .rms. In all these cases we find that price-marginal cost margins and demand elasticities may influence PWL in a counterintuitive way. We also provide conditions under which PWL increases or decreases with concentration

Effective and economic ecological weed management approaches for managing weeds in rice in the era of climate change

Rice will continue to be one of the major staple food expected 9 billion global population by 2050. Weeds are major constraints in limiting rice productivity to meet the increasing food demand. Weeds are more severe constraints in dry-direct-seeded with lower environmental foot print. Climate resilient rice cultivars, with greater competitiveness against weeds, play a key role in ecologically managing weeds

Holographic inflation in non-static plane symmetric space-time

The current analysis uses the non-static plane symmetric space-time to dynamically examine the holographic dark energy model as a candidates of IR cut-offs (specifically Hubble's and Granda-Oliveros cut-off). Using the Markov Chain Monte Carlo (MCMC) method, we estimate the best fit values for the model parameters imposed from the combined datasets of $CC+SC+BAO$. Now, it has been found that the characteristics of space-time that have been addressed and formulated using both models are flat universe and observed that the model appears to be in good agreement with the observations. In addition, we investigate the behavior of equation of state parameters along with the energy conditions. Finally, we found that in both the cut-offs the models predict that the present and late universe are accelerating and the equation of state parameter behaves like the quintessence model.Comment: 15-pages; 13-figure

Unleashing Enhanced Compressive Strength: 3D Printed Octopus-Inspired Suction Cups Using Topological Engineering

Nature’s intricate designs and efficient functionality have evolved over millions of years to thrive in challenging environments while minimizing energy consumption and ecological impact. Inspired by nature’s strategies, the manufacturing industry and academic research strive to develop materials and designs that exhibit high strength. The octopus, a remarkable marine creature, exemplifies a complex and adaptive design. It has eight arms aligned with numerous tactile suction cups having a specialized geometry and cavity. This study employed fused deposition modeling (FDM) printers to model and fabricate octopus-inspired suction cups. We examined different aspect ratios and shapes of cavities, such as cuboids, cylinders, and octopus suction cup cavities, while maintaining similar outer geometry. The compressive test proved that the inside cavity plays a significant role in enhancing strength due to stress distribution and is represented as a robust biomimetic design. The finite element analysis (FEA) is also developed to corroborate the experimental findings. The statistical validation of the experimental results is achieved through a multilinear regression equation. Our findings demonstrate that the naturally evolved octopus structure exhibits superior compressive strength, enhanced energy absorption, and the ability to generate negative pressure, rendering it highly suitable for gripping, suction, and shock-absorption applications

Photoelectron spectroscopy of excited molecular states

Results of studies of ion rotational and vibrational distributions for resonance enhanced multiphoton ionization are discussed

A development cooperation Erasmus Mundus partnership for capacity building in earthquake mitigation science and higher education

Successful practices have shown that a community’s capacity to manage and reduce its seismic risk relies on capitalization on policies, on technology and research results. An important role is played by education, than contribute to strengthening technical curricula of future practitioners and researchers through university and higher education programs. EUNICE is a European Commission funded higher education partnership for international development cooperation with the objective to build capacity of individuals who will operate at institutions located in seismic prone Asian Countries. The project involves five European Universities, eight Asian universities and four associations and NGOs active in advanced research on seismic mitigation, disaster risk management and international development. The project consists of a comprehensive mobility scheme open to nationals from Afghanistan, Bangladesh, China, Nepal, Pakistan, Thailand, Bhutan, India, Indonesia, Malaysia, Maldives, North Korea, Philippines, and Sri Lanka who plan to enroll in school or conduct research at one of five European partner universities in Italy, Greece and Portugal. During the 2010-14 time span a total number of 104 mobilities are being involved in scientific activities at the undergraduate, masters, PhD, postdoctoral and academic-staff exchange levels. Researchers, future policymakers and practitioners build up their curricula over a range of disciplines in the fields of earthquake engineering, seismology, disaster risk management and urban planning