Bipolaron Formation in a Strong Coupling Polaronic Metal

We study the formation of bipolarons in the Holstein–Peierls–Hubbard model on a square lattice. This model, for sufficiently small Coulomb interaction, is known to describe a narrow band metallic state, in which the carriers are heavily dressed by the strong interaction with local, dispersionless (Einstein) phonons. To deal with the absence of a small expansion parameter, we use a combination of canonical transformations and a variational treatment in terms of squeezed phonon states. The coexistence of polarons and bipolarons is considered and found compatible for reasonable values of the system parameters, namely the electronic hopping term t, the phonon frequency and the electron–phonon coupling constant g. The possibility of bipolaron condensation is studied within this model and found to occur in the same parameter range as the polaron–bipolaron coexistence regime.     

Polaronic Properties of an Ion in a Bose-Einstein Condensate in the Strong-Coupling Limit

Cold atoms can be used to model the Fröhlich polaron Hamiltonian using an impurity in a condensate. To probe the strong-coupling regime (which remains elusive in the solid state) charged impurities can be better suited that neutral impurities. However, the ion–atom interaction leads to a stronger depletion of the condensate as compared to the depletion from interaction with neutral impurities, and a good correspondence between the Fröhlich Hamiltonian and the cold atom system is only possible when the Bogoliubov approximation is valid. We use a strong-coupling variational approach to estimate an upper limit to the ion-atom coupling strength (expressed through a dimensionless coupling constant). The all-coupling path integral approach is used to estimate the values of the coupling constant that would need to be reached to probe the strong-coupling polaron physics. From these two approaches, we identify a regime where ions in condensates can model strong-coupling polarons and we calculate ground state properties in this regime.     

Polaronic relaxation in Ca2TiMnO6 at low temperatures

Dielectric properties of Ca₂TiMnO₆ (CTM) were systematically investigated. Our results revealed that (1) the observed relaxation does not feature one clear Arrhenius behavior, (2) the peak intensity of the imaginary part of the complex permittivity can be well expressed by a relation similar to the Fermi–Dirac distribution function, and (3) the colossal dielectric behavior of the sample can be well understood based on the framework of universal dielectric response. These features indicate that the dielectric properties of CTM are related to polaron relaxation.     

Local Polaronic Effects in Compounds with Atoms of Transition Metals

The e-ph coupling may be of the different strength for different electronic bands. If coupling is strong enough for one or more bands, polaronic effects practically decouple these bands from the rest. Single ions being dressed by strong e-ph interactions move in the local potentials having two or more minima, and hence, can be viewed as the system of the Ising spins. Intersite interactions via the RKKY-type exchange by the electron-hole pairs tend to order the latter thus providing the CDW instability mechanism with a structural vector, Q that has nothing in common with the Fermi surfaces parameters. Among the most typical manifestations of such strong e-ph coupling in the system are large characteristic energy scales significantly exceeding the temperatures for the onset of the CDW phase. The available experimental data support interpretation of properties of the transition-atoms-dichalcogenides and the compounds of the A15 group in terms of the local polaronic effects.     

Quasiparticles and Polaronic Effects in Crystals,Fermi Gasses and Fermi Liquids

We study the effect of quantum and classical phase fluctuations on the phase transitions in the system of Josephson-junction arrays. We employed a variational method for calculating the Gaussian type fluctuation of the phase in the Josephson-junction array lattice systems without and with an external magnetic field. We investigate the spectrum of collective excitations and the effects of collective excitations on the transport properties of Josephson-junction arrays. We showed that the Hamiltonian for the lattice system of the Josephson junction is the same as the Hamiltonian for the classical or quantum two-dimensional interacting rotators. We also showed that the dynamics of fluctuations of the phase in the lattice system of Josephson junction is very similar to the lattice dynamics of the lattice in crystals. We also showed that in the lattice system of Josephson junctions there is the collective acoustic mode similar to the acoustic mode in the crystal lattice, and this mode may lead to the dissipation of the Josephson current in the superconducting array of Josephson junctions. The speed of sound of the collective acoustic mode of the phase fluctuation depends on the Josephson coupling energy and the Coulomb charging energy. The contribution of the collective acoustic mode to the low temperature specific heat is the same as the contribution of the acoustic phonons to the specific heat of crystals. We also discuss the future development of results and their application.     

Temperature Dependence of Polaronic Correction to the Ground State Energy in a GaAs Parabolic Quantum Dot

Within the framework of second-order Rayleigh-Schrodinger perturbation theory (RSPT), the polaronic corrections to the ground state (GS) energy of an electron in both two-dimensional (2D) and three-dimensional (3D) parabolic quantum dots (QDs) are presented at finite temperature. We apply our calculations to GaAs. It is found that the polaronic corrections to the GS energy of an electron in both 2D and 3D QDs increase with temperature increasing and size of the QD decreasing. Furthermore, this trend is much more pronounced with dimensionality decreasing.     

Wavelength Shifts in Hg198 As a Function of Temperature

The wavelength shifts for the green (5460A) and blue (4358A) lines emitted from an electrodeless discharge lamp of Hg¹⁹⁸ have been studied as a function of the temperature of the water jacket of the source. The values of the wavelength shifts observed for the green and the blue lines are (8.5±3) 10⁻⁶ A/°C and (2±1) 10⁻⁶ A/°C, respectively.     

Polaronic Correction to the Ground State Energy and?Effective Mass in a Two- and Three-Dimensional Quantum Dot

A Landau-Pekar variational theory is employed to obtain an analytical expression for the polaronic correction to the ground state energy and the effective mass of an electron confined in a symmetric quantum dot potential in polar semiconductor in both two and three dimensions. It is found that polaronic correction is more pronounced in two dimension than that in three dimensional one and increases with the decrease in size of the quantum dot.     

Paradigmatic Shifts in Automobile Manufacturing

ABSTRACT

One of the greatest problems facing the U.S. auto industry is the erosion of its manufacturing base. Another is the increasing challenge from Japan, which keeps building on its solid postwar accomplishments mapped out by such pioneers as Taiichi Ohno and Shigeo Shingo. Their enduring legacy includes a reliance on the firm's human resources for maintaining productivity and quality control. The Japanese paradigm thus has a built-in mechanism for self-improvement and competitiveness enhancement.

The continued strife in Detroit suggests that the older American paradigm must be restructured; its top-down way of conducting business must allow labor to become a genuine partner with management instead of an adversary. The Japanese immigrant plants in the United States clearly show the way to do this. While such restructuring is frequently time-consuming, the period available for reform dwindles as the Asians keep strengthening their U.S. operations.     

Polaronic Trions at the MoS2/SrTiO3 Interface

The reduced electrical screening in 2D materials provides an ideal platform for realization of exotic quasiparticles, that are robust and whose functionalities can be exploited for future electronic, optoelectronic, and valleytronic applications. Recent examples include an interlayer exciton, where an electron from one layer binds with a hole from another, and a Holstein polaron, formed by an electron dressed by a sea of phonons. Here, a new quasiparticle is reported, “polaronic trion” in a heterostructure of MoS₂/SrTiO₃ (STO). This emerges as the Fröhlich bound state of the trion in the atomically thin monolayer of MoS₂ and the very unique low energy soft phonon mode (≤7 meV, which is temperature and field tunable) in the quantum paraelectric substrate STO, arising below its structural antiferrodistortive (AFD) phase transition temperature. This dressing of the trion with soft phonons manifests in an anomalous temperature dependence of photoluminescence emission leading to a huge enhancement of the trion binding energy (≈70 meV). The soft phonons in STO are sensitive to electric field, which enables field control of the interfacial trion–phonon coupling and resultant polaronic trion binding energy. Polaronic trions could provide a platform to realize quasiparticle‐based tunable optoelectronic applications driven by many body effects.     

Controlled Lateral Shifts

When using detector arrays for image evaluation, differences in the sensitivity or the non-linear characteristic of individual detectors limit contrast resolution, especially if temporal changes of detector performance are involved. It is shown in this paper that it is possible to measure the momentary individual detector performances with the help of quick lateral shifts between detector array and image distribution. For linear detectors one shift per image dimension is necessary. Allowance for sensitivity differences results in the calculation of relative illuminance distributions. For non-linear detectors, two shifts per image dimension are necessary, and relative contrasts of the image distribution can be calculated.     

Time-Dependent Frequency Shifts in the Hydrogen Maser

A long-term frequency shift, with respect to TAI, has been observed in each of two hydrogen masers by direct frequency comparisons between them and primary cesium standards. The shift is attributed to an increase in the wall shift of the storage bulb in the maser. Depending on the storage bulb used, this increase was found to be between 3 × 10-13 and 8 × 10-13 per year. Possible reasons for the observed shift are discussed.     

Intensity-dependent Phase Shifts in Nonlinear Coupling Devices

Abstract

For nonlinear coupling devices, general solutions using Stokes parameters fail to give complete information of phase shifts, as they only provide the phase-shift difference between the two outputs of coupling waveguides (or two cores for fibre coupling devices). Thus the standard Stokes parameter formulation is not sufficient for some applications in which the nonlinear phase shifts through the devices are of great concern. The analysis given here presents complete and exact solutions for nonlinear phase shifts in optical coupling devices for the first time. This reveals unusual behaviour of the nonlinear phase shifts because, in a certain input power range, a small change of input power can bring about a large change in the nonlinear phase shift. Some basic characteristics of the nonlinear phase shifts and their potential influence on application of coupling devices to all-optic signal processing are discussed.     

Shifts in plasmon resonance due to charging of a nanodisk array in argon plasma

A method for generating charge-induced plasmonic shifts, using argon plasma to charge nanoparticle arrays, is presented. Particles develop a negative charge, due to enhanced collisions with high-temperature electrons, in low-temperature plasmas. The negative charge generated causes a blue shift in the localized surface plasmon resonance. The dynamics of the shift were recorded and discussed. This effect could be used as a real-time method for studying the dynamics for charging in plasma.     

Lateral Shifts for Spin Electrons in a Hybrid Magnetic-Electric-Barrier Nanostructure Modulated by Spin-Orbit Couplings

We theoretically investigate how to modulate spin-dependent lateral shifts by the spin-orbit coupling (SOC) in a hybrid magnetic-electric-barrier (MEB) nanostructure, which can be experimentally realized by depositing a ferromagnetic (FM) stripe and a Schottky metal (SM) stripe on the top and bottom of the semiconductor heterostructure, respectively. Two kinds of ROCs, Rashba SOC (RSOC) and Dresselhaus SOC (DSOC), are taken into account fully. The Schrödinger equation of the spin electron in the hybrid MEB nanostructure is exactly solved by using the improved transfer-matrix method (ITMM), and the lateral shift and its spin polarization are numerically calculated with the help of the stationary phase method (SPM). Theoretical analysis indicates that the spin polarization effect in the lateral shift still exists in the hybrid MEB nanostructure when the SOCs are considered. Numerical simulations show that both magnitude and sign of the spin polarization effect in lateral shifts vary strongly with the strengths of RSOC and DSOC. These interesting features may offer an effective means to control the behavior of spin-polarized electrons in the semiconductor nanostructure, and such a hybrid MEB nanostructure serves as a SOC-manipulable spatial spin splitter for spintronic applications.     

Shifts in dialysis patients from natural disasters in 2005

Hurricanes Katrina and Rita alerted the world to North America's Gulf Coast's vulnerability to natural disasters. This vulnerability was most evident in poor, minority and elderly populations, and patients with chronic diseases requiring treatment such as dialysis. These hurricanes resulted in massive devastation of the healthcare infrastructure, including dialysis units, across the Gulf Coast region, and often resulted in temporary or permanent closure of dialysis units, predominantly in the New Orleans metropolitan area; however, Hurricane Rita primarily affected Lake Charles. Most notable was the population shift of dialysis patients in Louisiana due to hurricanes Katrina and Rita. Before the 2005 hurricane season, there were 2011 and 362 dialysis patients residing in the parishes (the Louisiana equivalent to counties) most affected by hurricanes Katrina and Rita, respectively. Each of these parishes had experienced increases in dialysis patient populations over the past 5 years. However, following the storms, there were 1014 and 316 dialysis patients residing in the affected parishes. Reasons for the population shifts were multifactorial in nature and included individual, provider, and healthcare system factors. As patients and physicians return to these affected areas, dialysis services will need to be reallocated based on new demographics and distribution of services in Louisiana communities. In planning for future dialysis services, adaptations will need to occur to prevent future interruption of services and loss of patient access to dialysis services.