Spectroscopy and Directed Transport of Topological Solitons in Crystals of Trapped Ions.

We study experimentally and theoretically discrete solitons in crystalline structures consisting of several tens of laser-cooled ions confined in a radio frequency trap. Resonantly exciting localized, spectrally gapped vibrational modes of the soliton, a nonlinear mechanism leads to a nonequilibrium steady state of the continuously cooled crystal. We find that the propagation and the escape of the soliton out of its quasi-one-dimensional channel can be described as a thermal activation mechanism. We control the effective temperature of the soliton's collective coordinate by the amplitude of the external excitation. Furthermore, the global trapping potential permits controlling the soliton dynamics and realizing directed transport depending on its topological charge.

Nanofriction in Cavity Quantum Electrodynamics.

The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

The impact of vitamin D levels on glycemic control and bone mineral density in postmenopausal women with type 2 diabetes.

OBJECTIVES: Whether glycemic control contributes to a decreased number of fractures or favorably impacts bone density in patients with type 2 diabetes mellitus (T2DM)has not been well established. Vitamin D (25 (OH) D3) deficiency appears to be related to glycemic control in patients with T2DM. The aim of this study was to determine the relationship between 25 (OH) D3 levels, glycemic control, bone mineral density (BMD), and the development of osteoporotic fractures (OPF) in postmenopausal women with T2DM. METHODS: We reviewed the charts of 110 postmenopausal women diagnosed with T2DM. Glycosylated hemoglobin A1c (HbA1c) values over the previous 5 years were recorded and an average was obtained. Based on these values,the patients were divided into three groups: optimal,suboptimal, and poor control. Bone mineral density and 25(OH) D3 levels were also recorded. RESULTS: In the group of patients with poorly controlled T2DM, 25 (OH) D3 levels were not significantly lower in comparison with the optimal control group 19.29 ± 7.70 vs 17.26 ± 6.93 (p = 0.53). No statistically significant linear relationship between HbA1c and 25 (OH) D3 levels( r(s) = −0.17, p = 0.06) was established. The frequency of osteoporosis and osteopenia was not significantly different between groups. The group with optimal glycemic control had an increased number of OPF events (p = 0.04). CONCLUSIONS: We do not appreciate a significant relationship between 25 (OH) D3 levels and glucose control or OPF. Therefore, more studies are needed to identify the specific effect of 25 (OH) D3 in T2DM physiopathology.

Entanglement generation using discrete solitons in Coulomb crystals.

Laser-cooled and trapped ions can crystallize and feature discrete solitons that are nonlinear, topologically protected configurations of the Coulomb crystal. Such solitons, as their continuum counterparts, can move within the crystal, while their discreteness leads to the existence of a gap-separated, spatially localized motional mode of oscillation above the spectrum. Suggesting that these unique properties of discrete solitons can be used for generating entanglement between different sites of the crystal, we study a detailed proposal in the context of state-of-the-art experimental techniques. We analyze the interaction of periodically driven planar ion crystals with optical forces, revealing the effects of micromotion in radio-frequency traps inherent to such structures, as opposed to linear ion chains. The proposed method requires Doppler cooling of the crystal and sideband cooling of the soliton's localized modes alone. Since the gap separation of the latter is nearly independent of the crystal size, this approach could be particularly useful for producing entanglement and studying system-environment interactions in large, two- and possibly three-dimensional systems.

Trapping of topological-structural defects in Coulomb crystals.

We study experimentally and theoretically structural defects which are formed during the transition from a laser cooled cloud to a Coulomb crystal, consisting of tens of ions in a linear radio frequency trap. We demonstrate the creation of predicted topological defects ("kinks") in purely two-dimensional crystals and also find kinks which show novel dynamical features in a regime of parameters not considered before. The kinks are always observed at the center of the trap, showing a large nonlinear localized excitation, and the probability of their occurrence saturates at ∼0.5. Simulations reveal a strong anharmonicity of the kink's internal mode of vibration, due to the kink's extension into three dimensions. As a consequence, the periodic Peierls-Nabarro potential experienced by a discrete kink becomes a globally confining potential, capable of trapping one cooled defect at the center of the crystal.

Precise experimental investigation of eigenmodes in a planar ion crystal.

The accurate characterization of eigenmodes and eigenfrequencies of two-dimensional ion crystals provides the foundation for the use of such structures for quantum simulation purposes. We present a combined experimental and theoretical study of two-dimensional ion crystals. We demonstrate that standard pseudopotential theory accurately predicts the positions of the ions and the location of structural transitions between different crystal configurations. However, pseudopotential theory is insufficient to determine eigenfrequencies of the two-dimensional ion crystals accurately but shows significant deviations from the experimental data obtained from resolved sideband spectroscopy. Agreement at the level of 2.5×10(-3) is found with the full time-dependent Coulomb theory using the Floquet-Lyapunov approach and the effect is understood from the dynamics of two-dimensional ion crystals in the Paul trap. The results represent initial steps towards an exploitation of these structures for quantum simulation schemes.

Quantum coherence of discrete kink solitons in ion traps.

We propose to realize quantized discrete kinks with cold trapped ions. We show that long-lived solitonlike configurations are manifested as deformations of the zigzag structure in the linear Paul trap, and are topologically protected in a circular trap with an odd number of ions. We study the quantum-mechanical time evolution of a high-frequency, gap separated internal mode of a static kink and find long coherence times when the system is cooled to the Doppler limit. The spectral properties of the internal modes make them ideally suited for manipulation using current technology. This suggests that ion traps can be used to test quantum-mechanical effects with solitons and explore ideas for the utilization of the solitonic internal modes as carriers of quantum information.

Common problems in pediatric gynecology.

A knowledge of the special concerns and physiology in pediatric female patients allows the physician to obtain pertinent histories and appropriate examinations. This information permits diagnosis and treatment of sequelae of sexual abuse, common gynecologic infections, and trauma. More complex problems, such as determination of sources of vaginal bleeding and endocrinopathies, also can be evaluated. Finally, benign and malignant conditions affecting the internal and external genitalia may be diagnosed and treated or referred to a subspecialist as needed.

Urethral healing in rabbits.

We studied urethral healing in New Zealand white rabbits by histological examination after insult (urethral catheter) or injury (urethrotomy) specifically for acute and chronic inflammation, fibrosis, fistulas, squamous metaplasia, foreign body giant cells and urethral dilatation. Urethral catheterization resulted in increased inflammation and fibrosis compared to noncatheterized animals. Skin closure techniques and materials resulted in an inflammatory response that may extend to and involve the urethra. Minor differences in suture size were not an important variable but the persistence of suture material may have a role in the degree of inflammation and the formation of foreign body giant cells. Transepithelial closure techniques drag epithelial cells into subcutaneous tissues and may predispose to fistula formation.

Detection of testicular torsion by magnetic resonance imaging in a rat model.

Testicular torsion is one of the most common pediatric urological emergencies. Incorrect or delayed diagnosis contributes significantly to morbidity. We previously have shown that magnetic resonance displays scrotal contents with great detail using hydrogen concentration weighted and T2 weighted images. Sprague-Dawley rats underwent either unilateral 720-degree testicular torsion or a sham procedure. Magnetic resonance images were obtained at intervals with a 3 or 5-inch surface coil. Scans after surgical torsion showed a characteristic spiral distortion of the fascial planes of the spermatic cord, not seen in the sham animals, as well as a decrease in testicular size with prolonged torsion.

MR imaging of the scrotum: pathologic conditions.

The utility of high-resolution magnetic resonance (MR) imaging in studying a variety of intratesticular and extratesticular pathologic conditions was assessed. The high magnetic signal intensity of the testis provided an excellent background for visualization of intratesticular abnormalities. Except for old blood, all intratesticular processes were less intense than testis, especially on T2-weighted images. The visualization of the tunica albuginea is a distinct advantage, allowing its assessment in cases of trauma or testicular tumors. Epididymal and spermatic cord abnormalities were easily recognized. All pathologic conditions were best seen on T2-weighted images acquired in the coronal plane. Balanced images allowed for tissue characterization.

Magnetic resonance imaging of the cryptorchid testis.

Magnetic resonance imaging was used to evaluate seven patients with undescended testes. In six patients the presence or absence of testicular tissue was predicted correctly prior to surgery. Spermatic cord structures, if present, were accurately visualized in all patients.