Het psychologisch welbevinden van Nederlandse adolescenten met lesbische moeders die gebruik maakten van een bekende, niet-anonieme of anonieme spermadonor:Is donortype belangrijk?

Until 2004, Dutch women seeking donor insemination through medical facilities could opt for open-identity or anonymous donors. Currently, Dutch medical facilities are only allowed to use sperm from open-identity donors. Focusing on adolescents who were born before 2004, the present study provides a unique opportunity to compare the well-being of those conceived through different donor types: known, open-identity, or anonymous. The present study is based on 67 Dutch adolescents (meanage=16.04) conceived through sperm donation in lesbian-mother families. Participating adolescents were asked to complete the Rosenberg Self-Esteem Scale, the Youth Self-Report, and to answer questions about their donor. Thirty-three adolescents were conceived through known, 22 through open-identity, and 12 through anonymous donors. No significant differences were found on self-esteem or problem behavior among adolescents conceived through the three donor types. Likewise, no significant differences were found on these variables for adolescents with known donors who indicated that these men did or did not play important roles in their lives. Feeling uncomfortable about not knowing one’s donor was associated with lower levels of self-esteem and more externalizing problem behavior. That donor type has no bearing on adolescent self-esteem and problem behavior may help in guiding the donor choices of prospective lesbian parents

Transition to parenthood and quality of parenting among gay, lesbian and heterosexual couples who conceived through assisted reproduction

Little research has focused on the emotions felt during pregnancy and early parenthood as well as the initial quality of parenting displayed by first-time parents who conceived using assisted reproduction technologies (surrogacy, donor insemination, and in vitro fertilization). Research on primary and secondary caregivers in gay, lesbian, and heterosexual families is especially sparse. The current study examined 35 gay-father families, 58 lesbian-mother families and 41 heterosexual-parent families with their infants. Families were assessed at home when their infants were 4 months old (±14 days), and each parent participated in an audio-recorded standardized semi-structured interview in which we explored parental feelings during pregnancy, feelings about the parental role, perceived parental competence, the enjoyment of parenthood, expressed warmth and emotional over-involvement of parents. 13 Heterosexual parents reported less positive feelings in early pregnancy than lesbian parents, while gay parents reported less positive feelings at the end of pregnancy than lesbian mothers and more positive feelings about parenthood during the first post-partum weeks than heterosexual parents. There was no interaction between family type and caregiver role on reported feelings, or on perceived competence, enjoyment, warmth, and involvement. The present findings elucidate the transition to parenthood among first-time parents conceiving through assisted reproductive technologies, and especially contribute to our knowledge about gay fathers who became parents through surrogacy

CaB_6: a new semiconducting material for spin electronics

Ferromagnetism was recently observed at unexpectedly high temperatures in La-doped CaB_6. The starting point of all theoretical proposals to explain this observation is a semimetallic electronic structure calculated for CaB_6 within the local density approximation. Here we report the results of parameter-free quasiparticle calculations of the single-particle excitation spectrum which show that CaB_6 is not a semimetal but a semiconductor with a band gap of 0.8 eV. Magnetism in La_xCa_{1-x}B_6 occurs just on the metallic side of a Mott transition in the La-induced impurity band.Comment: 4 pages, 1 postscript figur

The contribution of myelin to magnetic susceptibility-weighted contrasts in high-field MRI of the brain

T(2)*-weighted gradient-echo MRI images at high field (≥ 7T) have shown rich image contrast within and between brain regions. The source for these contrast variations has been primarily attributed to tissue magnetic susceptibility differences. In this study, the contribution of myelin to both T(2)* and frequency contrasts is investigated using a mouse model of demyelination based on a cuprizone diet. The demyelinated brains showed significantly increased T(2)* in white matter and a substantial reduction in gray-white matter frequency contrast, suggesting that myelin is a primary source for these contrasts. Comparison of in-vivo and in-vitro data showed that, although tissue T(2)* values were reduced by formalin fixation, gray-white matter frequency contrast was relatively unaffected and fixation had a negligible effect on cuprizone-induced changes in T(2)* and frequency contrasts

Electronic Structure of the Complex Hydride NaAlH4

Density functional calculations of the electronic structure of the complex hydride NaAlH4 and the reference systems NaH and AlH3 are reported. We find a substantially ionic electronic structure for NaAlH4, which emphasizes the importance of solid state effects in this material. The relaxed hydrogen positions in NaAlH4 are in good agreement with recent experiment. The electronic structure of AlH3 is also ionic. Implications for the binding of complex hydrides are discussed.Comment: 4 pages, 5 figure