Maximum relative excitation of a specific vibrational mode via optimum laser pulse duration

For molecules and materials responding to femtosecond-scale optical laser pulses, we predict maximum relative excitation of a Raman-active vibrational mode with period T when the pulse has an FWHM duration of 0.42 T. This result follows from a general analytical model, and is precisely confirmed by detailed density-functional-based dynamical simulations for C60 and a carbon nanotube, which include anharmonicity, nonlinearity, no assumptions about the polarizability tensor, and no averaging over rapid oscillations within the pulse. The mode specificity is, of course, best at low temperature and for pulses that are electronically off-resonance, and the energy deposited in any mode is proportional to the fourth power of the electric field.Comment: 5 pages, 4 figure

5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetra­propyn­yloxy-2,8,14,20-tetra­thia­calix[4]arene

The title compound [systematic name: 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra­propyn­yloxy-2,8,14,20-tetra­thia­calix[4]arene], C52H56O4S4, is an alkyl­ated product bearing four propyne groups at the lower rim of a 5,11,17,23-tetra-tert-butyl-tetrathia­calix[4]arene. The mol­ecule is located on a crystallographic twofold rotation axis, running through two S atoms and perpendicular to the long axis of the mol­ecule. The four propyne groups, located in an alternate fashion above and below the mean plane of the four S atoms, are almost parallel to the calixarene long axis. The dihedral angle between the two crystallographically independent benzene rings is 86.77 (14)°. Two tert-butyl groups are disordered over two positions with site occupancies of 0.59 (2) and 0.41 (2)

Bis(4-amino­benzene­sulfonato-κO)bis­(propane-1,3-diamine-κ2 N,N′)copper(II) dihydrate

In the title compound, [Cu(C3H10N2)2(C6H6NO3S)2]·2H2O, the CuII atom lies on an inversion center and is hexa­coordinated by four N atoms from two 1,3-diamino­propane ligands and two O atoms from two 4-amino­benzene­sulfonate ligands in a trans arrangement, displaying a distorted and axially elongated octa­hedral coordination geometry, with the O atoms at the axial positions. A three-dimensional network is formed in the crystal structure through O—H⋯O, N—H⋯O and N—H⋯N hydrogen bonds

Integrating the interpersonal theory of suicide into the relations between cyber-victimization and suicidality among adolescents:A short-term prospective study

The relation between cyber-victimization and suicidality among adolescents has been well documented; however, the mechanisms underlying this association have not been well investigated. Drawing upon the interpersonal theory of suicide, this study aimed to examine the mediating mechanisms (i.e., thwarted belongingness and perceived burdensomeness) underlying longitudinal, bidirectional relations between cyber-victimization and suicidal ideation/attempts among adolescents and explore gender differences in the mechanisms. Participants were 497 Chinese adolescents (46.1 Mage = 13.28, SD = .66), who completed the assessment of cyber-victimization, thwarted belongingness, and perceived burdensomeness, suicidal ideation/attempts at three-time points. The time interval between each two assessments is two weeks. Results showed the reciprocal relations between cyber-victimization and thwarted belongingness/perceived burdensomeness, between thwarted belongingness and suicidal ideation/suicide attempts, and between perceived burdensomeness and suicide attempts. Longitudinal mediation analyses indicated that Time 2 thwarted belongingness mediated the relation between Time 1 cyber-victimization and Time 3 suicidal ideation/suicide attempts. Besides, the reverse pathway from Time 1 suicidal ideation to Time 3 cyber-victimization was also mediated by Time 2 thwarted belongingness, but it was only significant in females, as suggested by multiple-group analyses. According to the aforementioned results, the interpersonal theory of suicide provides a useful framework for understanding relations between cyber-victimization and suicidality. Findings suggest that intervention targeted at improving the need to belong may help reduce suicide risk and lower cyber-victimization. Anti-cyber-victimization should be integrated into suicide intervention and prevention programs, and gender differences should be taken into account in order to enhance the program’s effectiveness

Influence Maximization with Novelty Decay in Social Networks

Influence maximization problem is to find a set of seed nodes in a social network such that their influence spread is maximized under certain propagation models. A few algorithms have been proposed for solving this problem. However, they have not considered the impact of novelty decay on influence propagation, i.e., repeated exposures will have diminishing influence on users. In this paper, we consider the problem of influence maximization with novelty decay (IMND). We investigate the effect of novelty decay on influence propagation on real-life datasets and formulate the IMND problem. We further analyze the problem properties and propose an influence estimation technique. We demonstrate the performance of our algorithms on four social networks

Single-Molecule Experiments Reveal the Flexibility of a Per-ARNT-Sim Domain and the Kinetic Partitioning in the Unfolding Pathway under Force

AbstractPer-ARNT-Sim (PAS) domains serve as versatile binding motifs in many signal-transduction proteins and are able to respond to a wide spectrum of chemical or physical signals. Despite their diverse functions, PAS domains share a conserved structure. It has been suggested that the structure of PAS domains is flexible and thus adaptable to many binding partners. However, direct measurement of the flexibility of PAS domains has not yet been provided. Here, we quantitatively measure the mechanical unfolding of a PAS domain, ARNT PAS-B, using single-molecule atomic force microscopy. Our force spectroscopy results indicate that the structure of ARNT PAS-B can be unraveled under mechanical forces as low as ∼30 pN due to its broad potential well for the mechanical unfolding transition of ∼2 nm. This allows the PAS-B domain to extend by up to 75% of its resting end-to-end distance without unfolding. Moreover, we found that the ARNT PAS-B domain unfolds in two distinct pathways via a kinetic partitioning mechanism. Sixty-seven percent of ARNT PAS-B unfolds through a simple two-state pathway, whereas the other 33% unfolds with a well-defined intermediate state in which the C-terminal β-hairpin is detached. We propose that the structural flexibility and force-induced partial unfolding of PAS-B domains may provide a unique mechanism for them to recruit diverse binding partners and lower the free-energy barrier for the formation of the binding interface