Matter-Wave-Optical-Wave Mixing-Induced Transparency and a Nonhyperbolic Matter-Wave Quasisoliton in Quantum Gases.

The realization of atomic quantum gases has brought out surprising effects that have no correspondence in nonlinear optics with thermal gases, presenting intriguing and exciting challenges to the research discipline of nonlinear optics which has matured since the invention of the laser. Here, we show an unexpected optical wave-mixing gain cancellation effect in a quantum gas that restricts an, otherwise, strongly enhanced backward-propagating light-matter wave-mixing process. This results in a wave-mixing induced transparency and a nonhyperbolic quasi-matter-wave soliton that opens new research opportunities in hydrodynamic fluid research of degenerate quantum gases, such as phonon scattering in a two-dimensional sonic black hole horizon.

Versatile, dynamically balanced low-noise optical-field manipulator using a coherently prepared atomic medium.

We propose a versatile dynamic optical-field manipulator using a coherently prepared atomic medium. We show that by locking the pump power change with the two-photon detuning, a π-phase shifting can be realized with unit probe fidelity in a broad two-photon detuning range. The two-photon-insensitive π-phase-shift mode with significantly reduced fluctuation makes this scheme an attractive system for low-noise phase-gate operations.

Critical binding and electron scattering by symmetric-top polar molecules.

Quantum treatments of electron interactions with polar symmetric-top rotor molecules show features not present in the treatment of the linear-polar-rotor model. For symmetric tops possessing non-zero angular momentum about the symmetry axis, a new critical dipole can be defined that guarantees an infinite set of dipole-bound states independent of the values of the components of the inertial tensor. Additionally, for this same class, the scattering cross section diverges for all nonzero values of dipole moments and inertial moments, similar to solutions for the fixed linear dipole. Additional predictions are presented for electron affinities and rotational resonances of these systems.

Quadrupole-bound anions: efficacy of positive versus negative quadrupole moments.

A pseudopotential method is utilized to study the critical stability of model anions formed by long-range quadrupolar molecular potentials. Results indicate that critical quadrupole moments of simple point-charge triads do not serve well as predictors of real quadrupole-bound anions of systems with negative moments.

Non-Born-Oppenheimer approximation for very weakly bound states of molecular anions.

The influence of nuclear rotation on weak electron binding in the long range field of a linear polar molecule is treated in a way that leads ultimately, with suitable approximation, to the familiar equations for close coupling of electron-nuclear-rotational motions. Subsequently, a conventional pseudopotential approximation is invoked to examine the rotational spectra of HCN and DCN anions. It is shown that the number of rotationally excited anion states cannot be reliably predicted by assuming that zero binding occurs when the rotational energy equals the electron affinity obtained in the Born-Oppenheimer approximation. A method is suggested for combining accurate molecular orbital and parameterized pseudopotential methods to provide accurate electron affinities for very weakly bound anionic states.

Critical electron binding to linear electric quadrupole systems.

Results for critical quadrupolar moments for electron binding to fixed, point-charge systems are normalized, extended, and displayed in graphical forms. The influence of rotational degrees of freedom on critical binding to quadrupolar systems is examined through calculations of critical moments for electron binding to linear electric quadrupolar rotors. The results are presented for rotors covering useful ranges of size and inertial parameters. The effect of rotational degrees of freedom on critical binding is found to be less important for quadrupolar as compared to dipolar rotors.

Randomized evaluation of the single-use SoftSeal and the re-useable LMA Classic laryngeal mask.

A number of laryngeal masks are available, including both re-usable and single-use masks. Single-use laryngeal masks may decrease the risk of transmitting prion infections. We performed a single-blind randomized trial in 200 spontaneously breathing female patients under general anaesthesia with nitrous oxide, to compare a new single-use laryngeal mask, the SoftSeal (Portex Ltd, U.K.), with a re-usable laryngeal mask, the LMA Classic (Laryngeal Mask Company Ltd., Cyprus). The primary outcome was successful insertion at the first attempt. Size 4 single-use (n = 99) or re-usable (n = 100) laryngeal masks, inserted by experienced anaesthetists, were equivalent for successful placement at the first attempt (90% versus 91% respectively). The single-use mask was less easy to insert (47% difficult versus 9%, P < 0.001). Clinical and anatomical tests of position and function were similar. The cuff pressure of the re-usable mask increased significantly compared with the single-use mask (median +10 cm versus -2 cm H2O, P < 0.001). Forty per cent of patients allocated the single-use mask and 20% of those allocated the re-usable mask experienced sore throat at 24 hours postoperatively (P < 0.05). An estimation of cost per patient use was greater for the re-usable mask. We conclude that the SoftSeal single-use laryngeal mask and the LMA Classic re-usable laryngeal mask airway are of similar clinical utility in terms of successful insertion and airway maintenance. The re-usable laryngeal mask was easier to insert and associated with less postoperative sore throat, but costs were higher.

Protocol for the treatment of heterotopic bone formation in the temporomandibular joint.

The increase in patients with multiply operated temporomandibular joints (TMJs) has led to an increase in associated complications that respond unfavorably to additional attempts at correction. These can present as ankylosis and/or heterotopic bone formation. This has been recognized in other joint reconstruction, to a much more significant degree, and related to decreased vascularity, increased fibrosis and scarring, and decreased cellularity of the tissue in the joint space following multiple surgical procedures. Attempted correction of this problem can often lead to an increase in the etiology and to recurrence of the bone formation in spite of its debridement. Correction in other joints has evolved to include the use of thorough debridement of the heterotopic bone, alloplastic joint reconstruction, autologous fat grafting, and use of NSAIDs and low-dose radiatíon to decreaserecurrence.

Temporomandibular joint reconstruction with a custom total temporomandibular joint prosthesis: use in the multiply operated patient.

The purpose of this article is to report the development and use of the custom Christensen prosthesis (Garrett modification) for total temporomandibular joint reconstruction, its indications, protocol, adjunctive treatment and evolution to present design.

Observation of a critical concentration in laser-induced transparency and multiphoton excitation and ionization in rubidium.

We report the behavior of Autler-Townes splitting and production of a four-wave mixing (FWM) field in rubidium in the context of laser-induced transparency. Gain saturation of the FWM and simultaneous suppression of Autler-Townes splitting above a critical concentration are interpreted in terms of the odd-photon destructive interference effect. The results demonstrate that, when multimode lasers are used, odd-photon destructive interference significantly limits the high-efficiency and high-intensity FWM generation promised by early studies of laser-induced transparency.

Observations of predicted cooperative shifts in optically pumped stimulated emissions in Xe.

In a recent study Garrett showed that stimulated emissions can be suppressed and shifted under the influence of a wave-mixing interference [Phys. Rev. Lett. 70, 4059 (1993)]. We observe the predicted pressure-dependent frequency shifts in optically pumped stimulated emissions from Xe.