The Role of Multilevel Landau-Zener Interference in Extreme Harmonic Generation

Motivated by the observation of multiphoton electric dipole spin resonance processes in InAs nanowires, we theoretically study the transport dynamics of a periodically driven five-level system, modeling the level structure of a two-electron double quantum dot. We show that the observed multiphoton resonances, which are dominant near interdot charge transitions, are due to multilevel Landau-Zener-Stuckelberg-Majorana interference. Here a third energy level serves as a shuttle that transfers population between the two resonant spin states. By numerically integrating the master equation we replicate the main features observed in the experiments: multiphoton resonances (as large as 8 photons), a robust odd-even dependence, and oscillations in the electric dipole spin resonance signal as a function of energy level detuning

Women\u2019s human rights when experiencing humanitarian crises and conflicts: the impact of United Nations Security Council Resolutions on women, peace, security, and the CEDAW General Recommendation no. 30.

Violence and insecurity are strictly linked to unequal political, social, and economic power. However, the continuity of violence is obscured by masculinist and patriarchal rules of security within gendered structures, especially inside the division of public/private dimensions and spaces, of production-reproduction activities, and of conflicts of war/peace. Nowadays, there is a general perception of the gendered dimensions of humanitarian emergencies in public policy outcomes and more in general in institutional contexts where the central role of women in security and maintaining peace, at all levels of decision making, both prior to, during, and after the conflict stage, hostilities, and peace-keeping and peace-building stages, as well as in trying to pursue a condition of reconciliation and reconstruction, has been formally recognized at international level. Nevertheless, it is necessary to focus on some problems related to the conceptualization of and legal provision for \u2018gender based security\u2019 and its subsequent effects upon accountability, with particular reference to transitional justice and post-conflict societies. It is important to assess a range of contemporary issues implicated for women and security, such as violence and other forms of harassment in times of post-conflict

Dielectric mismatch and shallow donor impurities in GaN/HfO2 quantum wells

In this work we investigate electron-impurity binding energy in GaN/HfO$_2$ quantum wells. The calculation considers simultaneously all energy contributions caused by the dielectric mismatch: (i) image self-energy (i.e., interaction between electron and its image charge), (ii) the direct Coulomb interaction between the electron-impurity and (iii) the interactions among electron and impurity image charges. The theoretical model account for the solution of the time-dependent Schr\"odinger equation and the results shows how the magnitude of the electron-impurity binding energy depends on the position of impurity in the well-barrier system. The role of the large dielectric constant in the barrier region is exposed with the comparison of the results for GaN/HfO$_2$ with those of a more typical GaN/AlN system, for two different confinement regimes: narrow and wide quantum wells.Comment: 6 Pages, 7 figure

Perturbation theory for the one-dimensional optical polaron

The one-dimensional optical polaron is treated on the basis of the perturbation theory in the weak coupling limit. A special matrix diagrammatic technique is developed. It is shown how to evaluate all terms of the perturbation theory for the ground-state energy of a polaron to any order by means of this technique. The ground-state energy is calculated up to the eighth order of the perturbation theory. The effective mass of an electron is obtained up to the sixth order of the perturbation theory. The radius of convergence of the obtained series is estimated. The obtained results are compared with the results from the Feynman polaron theory.Comment: 9 pages, 2 figures, RevTeX, to be published in Phys. Rev. B (2001) Ap

The Effect of Water Walking on the Lower Limb Motion of Older Adults

The authors investigated the lower limb movements for older adults walking at their preferred speed in shallow water to obtain information to help professionals prescribe exercises in a pool. The 8 participants presented a) similar hip and thigh motions in water and on land, although a reduced thigh velocity was observed in the water; b) increased knee flexion at the beginning of the walking cycle and reduced knee extension throughout the walking cycle in water; c) reduced ankle motion throughout the walking cycle and plantar flexion during the swing phase in water; d) reduced shank motion and velocity in water; and e) different intralimb coordination resulting from a different relative phase between the shank and thigh segments. These results support the use of the water as an alternative environment for gait training in older adults. Water resistance and buoyancy factors seem to be the major forces to overcome when older adults walk in shallow water, so the authors suggest paying special attention to the immersion level and movement velocity when prescribing aquatic exercises

Quantum control theory for coupled 2-electron dynamics in quantum dots

We investigate optimal control strategies for state to state transitions in a model of a quantum dot molecule containing two active strongly interacting electrons. The Schrodinger equation is solved nonperturbatively in conjunction with several quantum control strategies. This results in optimized electric pulses in the THz regime which can populate combinations of states with very short transition times. The speedup compared to intuitively constructed pulses is an order of magnitude. We furthermore make use of optimized pulse control in the simulation of an experimental preparation of the molecular quantum dot system. It is shown that exclusive population of certain excited states leads to a complete suppression of spin dephasing, as was indicated in Nepstad et al. [Phys. Rev. B 77, 125315 (2008)].Comment: 24 pages, 9 figure

Enhancement of ATP levels and glucose metabolism during an infection by Chlamydia: NMR studies of living cells

The Chlamydia species are obligate intracellular bacteria that proliferate only within the infected cell. Since the extracellular bacteria are metabolically inert and there are no cell-free systems for characterizingChlamydia metabolism, we studied metabolic changes related to ATP synthesis and glycolysis in HeLa cells infected withChlamydia psittaci during the course of the 2-day infection cycle using noninvasive 31P and 13C NMR methods. We find that the infection stimulates ATP synthesis in the infected cell, with a peak of ATP levels occurring midway through the infection cycle, when most of the metabolically active bacteria are proliferating. The infection also stimulates synthesis of glutamate with a similar time course as for ATP. The stimulation is apparently due to an enhancement in glucose consumption by the infected cell, which also results in an increased rate of lactate production and glutamate synthesis as well as higher glycogen accumulation during the infection. Concurrently, infection leads to an increase in the expression of the glucose transporter, GLUT-1, on HeLa cells, which may account for the enhanced glucose consumption. The chlamydiae are thus able to stimulate glucose transport in the host cell sufficiently to compensate for the extra energy load on the cell represented by the infection

Extreme Harmonic Generation in Electrically Driven Spin Resonance

We report the observation of multiple harmonic generation in electric dipole spin resonance in an InAs nanowire double quantum dot. The harmonics display a remarkable detuning dependence: near the interdot charge transition as many as eight harmonics are observed, while at large detunings we only observe the fundamental spin resonance condition. The detuning dependence indicates that the observed harmonics may be due to Landau-Zener transition dynamics at anticrossings in the energy level spectrum.Comment: Related papers at http://pettagroup.princeton.ed