Continuous dynamical decoupling magnetometry

Solid-state qubits hold the promise to achieve unmatched combination of sensitivity and spatial resolution. To achieve their potential, the qubits need however to be shielded from the deleterious effects of the environment. While dynamical decoupling techniques can improve the coherence time, they impose a compromise between sensitivity and bandwidth, since to higher decoupling power correspond higher frequencies of the field to be measured. Moreover, the performance of pulse sequences is ultimately limited by control bounds and errors. Here we analyze a versatile alternative based on continuous driving. We find that continuous dynamical decoupling schemes can be used for AC magnetometry, providing similar frequency constraints on the AC field and improved sensitivity for some noise regimes. In addition, the exibility of phase and amplitude modulation could yield superior robustness to driving errors and a better adaptability to external experimental scenarios

Measurement of transverse hyperfine interaction by forbidden transitions

Precise characterization of a system's Hamiltonian is crucial to its high-fidelity control that would enable many quantum technologies, ranging from quantum computation to communication and sensing. In particular, nonsecular parts of the Hamiltonian are usually more difficult to characterize, even if they can give rise to subtle but non-negligible effects. Here we present a strategy for the precise estimation of the transverse hyperfine coupling between an electronic and a nuclear spin, exploiting effects due to nominally forbidden transitions during the Rabi nutation of the nuclear spin. We applied the method to precisely determine the transverse coupling between a nitrogen-vacancy center electronic spin and its nitrogen nuclear spin. In addition, we show how this transverse hyperfine coupling, which has been often neglected in experiments, is crucial to achieving large enhancements of the nuclear Rabi nutation rate.United States. Air Force Office of Scientific Research (Grant FA9550-12-1-0292)United States. Office of Naval Research (Grant N00014-14-1-0804

Sinus floor elevation with platelet-rich fibrin alone : a clinical retrospective study of 1-7 years

Several sinus floor elevation procedures for implant placement have been introduced. The present study aimed to evaluate the implants placed with Platelet-rich fibrin (PRF) alone in atrophic posterior maxillae and survival rates and the potential factors associated with implant loss. This retrospective study evaluated 71 implants in 34 patients after 1-7 years? follow-up time. Statistical models were used to determine the implant survival and the potential factors associated with loss. Overall, 7 implants were lost, and the cumulative survival rate at 7 years by implant-based and patient-bases analyses were 85.5% and 85.7%, respectively. The mean residual bone height (RBH) was 4.26 mm. The implant survival rate was significantly lower at RBH < 4 mm than RBH ? 4 mm. This retrospective study showed that sinus floor elevation with PRF alone could be applied in cases of lower RBH. However, it should be carefully performed in cases of RBH < 4 mm before surgery

Algivore or phototroph?: Plakobranchus ocellatus (Gastropoda) continuously acquires kleptoplasts and nutrition from multiple algal species in nature

The sea slug Plakobranchus ocellatus (Sacoglossa, Gastropoda) retains photosynthetically active chloroplasts from ingested algae (functional kleptoplasts) in the epithelial cells of its digestive gland for up to 10 months. While its feeding behavior has not been observed in natural habitats, two hypotheses have been proposed: 1) adult P. ocellatus uses kleptoplasts to obtain photosynthates and nutritionally behaves as a photoautotroph without replenishing the kleptoplasts; or 2) it behaves as a mixotroph (photoautotroph and herbivorous consumer) and replenishes kleptoplasts continually or periodically. To address the question of which hypothesis is more likely, we examined the source algae for kleptoplasts and temporal changes in kleptoplast composition and nutritional contribution. By characterizing the temporal diversity of P. ocellatus kleptoplasts using rbcL sequences, we found that P. ocellatus harvests kleptoplasts from at least 8 different siphonous green algal species, that kleptoplasts from more than one species are present in each individual sea slug, and that the kleptoplast composition differs temporally. These results suggest that wild P. ocellatus often feed on multiple species of siphonous algae from which they continually obtain fresh chloroplasts. By estimating the trophic position of wild and starved P. ocellatus using the stable nitrogen isotopic composition of amino acids, we showed that despite the abundance of kleptoplasts, their photosynthates do not contribute greatly to the nutrition of wild P. ocellatus, but that kleptoplast photosynthates form a significant source of nutrition for starved sea slugs. The herbivorous nature of wild P. ocellatus is consistent with insights from molecular analyses indicating that kleptoplasts are frequently replenished from ingested algae, leading to the conclusion that natural populations of P. ocellatus do not rely on photosynthesis but mainly on the digestion of ingested algae