Detecting and polarizing nuclear spins with double resonance on a single electron spin.

We report the detection and polarization of nuclear spins in diamond at room temperature by using a single nitrogen-vacancy (NV) center. We use Hartmann-Hahn double resonance to coherently enhance the signal from a single nuclear spin while decoupling from the noisy spin bath, which otherwise limits the detection sensitivity. As a proof of principle, we (i) observe coherent oscillations between the NV center and a weakly coupled nuclear spin and (ii) demonstrate nuclear-bath cooling, which prolongs the coherence time of the NV sensor by more than a factor of 5. Our results provide a route to nanometer scale magnetic resonance imaging and novel quantum information processing protocols.

A New Motif in Halogen Bonding: Cooperative Intermolecular S-Br⋠⋠⋠O, O⋠⋠⋠F, and F⋠⋠⋠F Associations in the Crystal Packing of α,ω-Di(sulfonyl bromide) Perfluoroalkanes.

We recently reported the first examples of S-Cl⋅⋅⋅O halogen bonding complemented by short F⋅⋅⋅F contacts between neighboring chains that resulted in stabilized crystals of ClSO2 (CF2 )4 SO2 Cl and ClSO2 (CF2 )6 SO2 Cl. More recently, other researchers studied our crystallographic data further using an Independent Gradient Model (IGM), and they suggested if one goes beyond IUPAC's proposed 'less than the sum of the van der Waals radii' criterion that even more noncovalent interactions between fluorine atoms on neighboring chains as well as Cl⋅⋅⋅Cl, Cl⋅⋅⋅S, O⋅⋅⋅F, and O⋅⋅⋅S attractive interactions can be found. With that said, we have prepared samples of the related BrSO2 (CF2 )n SO2 Br derivatives (where n=4, 6, 8, and others), which give rise to even stronger S-Br⋅⋅⋅O halogen bonding interactions complemented minimally by O⋅⋅⋅F and F⋅⋅⋅F intermolecular interactions as shown by X-ray crystallography and computational chemistry using IGM isosurface plots. Additional spectroscopic characterization (multinuclear NMR, FT-IR, and MS) of the disulfonyl bromide derivatives BrSO2 (CF2 )4 SO2 Br, BrSO2 (CF2 )6 SO2 Br, and BrSO2 (CF2 )8 SO2 Br has also been obtained as well as some preliminary spectroscopic evidence for BrSO2 (CF2 )2 SO2 Br and BrSO2 CF2 O(CF2 )2 OCF2 SO2 Br. The implication of these results toward the preparation of the corresponding disulfonyl iodides is discussed.

Self-similar modes of coherent diffusion.

Self-similar solutions of the coherent diffusion equation are derived and measured. The set of real similarity solutions is generalized by the introduction of a nonuniform phase, based on the elegant Gaussian modes of optical diffraction. In a light-storage experiment, the complex solutions are imprinted on a gas of diffusing atoms, and the self-similar evolution of both their amplitude and phase pattern is demonstrated. An algebraic decay depending on the mode order is measured. Notably, as opposed to the regular diffusion spreading, a subset of the solutions exhibits a self-similar contraction.

Evaluating psychotherapy.

The authors analyze the possible need for a standing national group to evaluate the efficacy and safety of the psychotherapies. The current need is for a body whose function is more scientifically evaluative and less regulatory than the Food and Drug Administration because available psychotherapies are less specific in their beneficial effects and less dangerous than are drugs and because the practice of psychotherapy cannot be restricted entirely to the health professions. Even so, the authors believe the main criteria for discerning the boundaries between research and established practice are in principle at least as clear for psychotherapy as for other health interventions.

Hepatic angiomyolipoma mimicking hepatocellular carcinoma.

Angiomyolipoma [AML] is a rare benign lipomatous tumour of the liver. It is typically echogenic on ultrasound, hypodense on computed tomography and hyperintense on magnetic resonance imaging. Its varied imaging appearance is due to the different proportion of the three cell types which make up the tumour. This is a case report of a hepatic AML mimicking hepatocellular carcinoma [HCC] with fatty change in a hepatitis B carrier. Diagnostic difficulty and implications on subsequent management are discussed in the context of an endemic region for HCC.

Communication in relationships and adolescent substance use: the influence of parents and friends.

This study focused on the openness of communication in teenagers' relationships with mother, father (or parental figure), and closest friend, and its correlation with teenagers' use of cigarettes, alcohol, marijuana, and other drugs. The predictive value for substance use of perceived pressure from friends, friends' substance use, and parents' substance use was also analyzed. The findings from questionnaires and interviews conducted with 37 students at an urban and a suburban/rural high school in New England are reported. The results suggest that the degree to which adolescents talk openly with their parents may influence the extent of their substance use. The presence of at least one "open" parental figure was associated with lower levels of all substance use. However, there was no evidence that openness with a close friend or perceived pressure from friends is related to substance use.