Generalized Strong Curvature Singularities and Cosmic Censorship

A new definition of a strong curvature singularity is proposed. This definition is motivated by the definitions given by Tipler and Krolak, but is significantly different and more general. All causal geodesics terminating at these new singularities, which we call generalized strong curvature singularities, are classified into three possible types; the classification is based on certain relations between the curvature strength of the singularities and the causal structure in their neighborhood. A cosmic censorship theorem is formulated and proved which shows that only one class of generalized strong curvature singularities, corresponding to a single type of geodesics according to our classification, can be naked. Implications of this result for the cosmic censorship hypothesis are indicated.Comment: LaTeX, 11 pages, no figures, to appear in Mod. Phys. Lett.

Emotion-based personality traits and associations with conflict tactics and relationship satisfaction in romantic relationships

The purpose of this study was to assess the role that emotion based personality traits play in conflict tactic choice and relationship satisfaction in romantic relationships. The researchers proposed that emotional intelligence and affective orientation influenced the choice of verbally aggressive or reasoning tactics use and their subsequent affects on overall relationship satisfaction. 159 participants, 84 men and 75 women, from a large Mid-Atlantic university participated in this study. Results showed that emotional intelligence and affective orientation were significantly correlated (r = .58), and that affective orientation in combination of the participants\u27 perceptions of their partner\u27s use of verbally aggressive, and reasoning tactics had the most influence on relationship satisfaction. There were gender differences in affective orientation and emotional intelligence, with females scoring higher, but not in the choice of conflict tactics

The Long, the Short, and the Micro: A PolyA Tale of Pax3 in Satellite Cells

The use of alternative polyadenylation sites is emerging as an important regulator of gene expression. In this issue of Cell Stem Cell, Boutet et al. (2012) report that alternative 3′UTRs of the Pax3 transcript restrict its expression to axial satellite cells through miR-mediated targeting of one of the isoforms

Molecular Mechanisms of Muscle Atrophy

AbstractSkeletal muscle atrophy has extreme adverse consequences. Molecular mechanisms that mediate the process of atrophy are not well defined. Recent studies have focused on diverse molecular cascades that control the activation of ubiquitin ligases, indicating that the involvement of the ubiquitin proteasome may be common to a range of atrophic stimuli

Coherent population oscillations with nitrogen-vacancy color centers in diamond

We present results of our research on two-field (two-frequency) microwave spectroscopy in nitrogen-vacancy (NV-) color centers in a diamond. Both fields are tuned to transitions between the spin sublevels of the NV- ensemble in the 3A2 ground state (one field has a fixed frequency while the second one is scanned). Particular attention is focused on the case where two microwaves fields drive the same transition between two NV- ground state sublevels (ms=0 -> ms=+1). In this case, the observed spectra exhibit a complex narrow structure composed of three Lorentzian resonances positioned at the pump-field frequency. The resonance widths and amplitudes depend on the lifetimes of the levels involved in the transition. We attribute the spectra to coherent population oscillations induced by the two nearly degenerate microwave fields, which we have also observed in real time. The observations agree well with a theoretical model and can be useful for investigation of the NV relaxation mechanisms.Comment: 17 page

A fast and reliable method for the delineation of tree crown outlines for the computation of crown openness values and other crown parameters

Numerous crown parameters (e.g., leaf area index, diameter, height, volume) can be obtained via the analysis of tree crown photographs. In all cases, parameter values are functions of the position of the crown outline. However, no standardized method to delineate crowns exists. To explore the effect of different outlines on tree crown descriptors, in this case crown openness (CO), and facilitate the adoption of a standard method free of user bias, we developed the program Crown Delineator that automatically delineates any outline around tree crowns following predetermined sensibility settings. We used different outlines to analyze tree CO in contrasting settings: using saplings from four species in young boreal mixedwood forests and medium-sized hybrid poplar trees from a low-density plantation. In both cases, the estimated CO increases when calculated from a looser outline, which had a strong influence on understory available light simulations using a forest simulator. These results demonstrate that the method used to trace crown outlines is an important step in the determination of CO values. We provide a much-needed computer-assisted solution to help standardize this procedure, which can also be used in many other situations in which the delineation of tree crowns is needed (e.g., competition and crown shyness)

Microwave saturation spectroscopy of nitrogen-vacancy ensembles in diamond

Negatively-charged nitrogen-vacancy (NV$^-$) centers in diamond have generated much recent interest for their use in sensing. The sensitivity improves when the NV ground-state microwave transitions are narrow, but these transitions suffer from inhomogeneous broadening, especially in high-density NV ensembles. To better understand and remove the sources of broadening, we demonstrate room-temperature spectral "hole burning" of the NV ground-state transitions. We find that hole burning removes the broadening caused by magnetic fields from $^{13}$C nuclei and demonstrate that it can be used for magnetic-field-insensitive thermometry.Comment: Main text: 5 pages, 4 figures. Supplement: 6 pages, 3 figure