A Program of Photometric Measurements of Solar Irradiance Fluctuations from Ground-based Observations

Photometric observations of the sun have been carried out at the San Fernando Observatory since early 1985. Since 1986, observations have been obtained at two wavelengths in order to separately measure the contributions of sunspots and bright facular to solar irradiance variations. Researchers believe that the contributions of sunspots can be measured to an accuracy of about plus or minus 30 ppm. The effect of faculae is much less certain, with uncertainties in the range of plus or minus 300 ppm. The larger uncertainty for faculae reflects both the greater difficulty in measuring the facular area, due to their lower contrast compared to sunspots, and the greater uncertainty in their contrast variation with viewing angle on the solar disk. Recent results from two separate photometric telescopes will be compared with bolometric observations from the active cavity radiometer irradiance monitor (ACRIM) that was on board the Solar Max satellite

On the intensity contrast of solar photospheric faculae and network elements

Sunspots, faculae and the magnetic network contribute to solar irradiance variations. The contribution due to faculae and the network is of basic importance, but suffers from considerable uncertainty. We determine the contrasts of active region faculae and the network, both as a function of heliocentric angle and magnetogram signal. To achieve this, we analyze near-simultaneous full disk images of photospheric continuum intensity and line-of-sight magnetic field provided by the Michelson Doppler Interferometer (MDI) on board the SOHO spacecraft. Starting from the surface distribution of the solar magnetic field we first construct a mask, which is then used to determine the brightness of magnetic features, and the relatively field-free part of the photosphere separately. By sorting the magnetogram signal into different bins we are able to distinguish between the contrasts of different concentrations of magnetic field. We find that the contrasts of active region faculae (large magnetogram signal) and the network (small signal) exhibit a very different CLV, showing that the populations of magnetic flux tubes are different. This implies that these elements need to be treated separately when reconstructing variations of the total solar irradiance with high precision. We have obtained an analytical expression for the contrast of photospheric magnetic features as a function of both position on the disk and magnetic field strength, by performing a 2-dimensional fit to the observations.Comment: 12 pages, 8 figures, uses aa.cl

Stepparents’ Attachment Orientation, Parental Gatekeeping, and Stepparents’ Affinity‐Seeking with Stepchildren

Remarried stepfamilies are a sizable portion of American families; in a 2011 Pew Center survey, 42% of respondents reported at least one stepfamily member. Family clinicians and researchers suggest that stepparents’ ability to develop close bonds with stepchildren may be critical to the well‐being of couple and family relationships. Using actor‐partner interdependence models to analyze dyadic data from 291 heterosexual remarried stepfamily couples, we explored factors related to stepparents’ efforts to befriend their stepchildren. Specifically, we evaluated how remarried parents’ gatekeeping and stepparents’ perceptions of their attachment orientations were associated with their own and their spouse's perceptions of stepparents’ affinity‐seeking behaviors. Securely attached stepparents and stepparents with anxious attachment orientations engaged more frequently in affinity behaviors than did stepparents with avoidant attachment orientations; there was no difference between securely attached and anxious stepparents. Stepparents’ reports of parents’ restrictive gatekeeping were strongly and negatively associated with both stepparents’ and parents’ reports of stepparent affinity‐seeking (actor and partner effects). Parents’ reports of their own restrictive gatekeeping were also negatively (but more weakly) associated with parents’ reports of stepparent affinity‐seeking. Implications for families, clinicians, and relationship researchers and theorists are discussed

Exploring structural and electronic effects in three isomers of tris{bis(trifluoromethyl)phenyl}borane: Towards the combined electrochemical-frustrated Lewis pair activation of H2

Three structural isomers of tris{bis(trifluoromethyl)phenyl}borane have been studied as the acidic com- ponent of frustrated Lewis pairs. While the 3,5-substituted isomer is already known to heterolytically cleave H2 to generate a bridging-hydride; ortho-substituents in the 2,4- and 2,5-isomers quench such reactivity through electron donation into the vacant boron pz orbital and steric blocking of the boron centre; as shown by electrochemical, structural and computational studies. Electrochemical studies of the corresponding borohydrides identify that the two-electron oxidation of terminal-hydrides occurs at more positive potentials than observed for [HB(C6F5)3]−, while the bridging-hydride oxidizes at a higher poten- tial still, comparable to that of free H2