Syntheses, crystal structures, and vibrational spectroscopic properties of MgCN2, SrCN2, and BaCN2

The alkaline-earth metal cyanamides MgCN* SrCN* and BaCN2 were prepared by the reaction of melamine with the metal nitrides (M&N2, Sr-jN, Ba3N2 ) at temperatures between 740 e C and 850 °C. MgCN2 was structurally characterized by X-ray analysis using powder methods (R3m, Ζ - 3 , a=327.34(1) pm, c-1412.82(5) pm). The crystal structures of SrCN2 and BaCN2 were determined from X-ray single crystal data (SrCN2 : Pnma, Ζ-A, 0-1241.0(2) pm, 6-396.3(2) pm, c-538.9(2) pm, BaCN2 : R3c, Z=18, e-1528.2(2) pm, c-70l.3(2) pm). All compounds consist of the respective cations and CN2 2~-anions with an increasing degree of distortion of the coordination polyhedra with increasing radii of the cations. The structural features are correlated with vibrational spectroscopic data

Tvrda ekskluzivna tvorba bariona-antibariona u sudarima 2-γ

We present a perturbative calculation of baryon pair production in two-photon collisions, γγ → BB, in which baryons are treated as quark-diquark systems. Our approach accounts for constituent mass effects in a systematic way. Taking the diquark-model parameters from foregoing studies of other electron- and photon-induced baryonic reactions, our results agree well with the most recent large momentum-transfer data for the p¯p, ΛΛ, and Σ0Σ¯0 channels.Izlažemo perturbativan račun tvorbe barionskog para, γγ → BB, u kojemu se barioni predstavljaju kao sustav kvark-dikvark. Ovaj pristup na sustavan način objašnjava učinke sastavnica (konstituenata) masa. Uzimajući parametre ranijih istraživanja drugih barionskih reakcija izazvanih elektronima i fotonima, postigli smo slaganje ishoda naših računa s najnovijim podacima za kanale p¯p, ΛΛ i Σ0 Σ¯0 na velikim prijenosima impulsa

Predicting the Timing of Social Transitions from Personal, Social and Socio-Economic Resources of German Adolescents

Social transitions are characterized by an increased heterogeneity in Western societies. Following the life course perspective, individual agency becomes central in shaping one’s life course. This article examines social transitions of adolescents using individual resource theory to explain differences of the timing of five transitions in partnership and family formation: the first sexual experience, the first intimate relationship, the first cohabitation, the first marriage, and the birth of the first child. Since little is so far known about how individual characteristics interact and influence the social transition to adulthood, we focus on the varying impacts of personal, social and socio-economic resources across the social life course. We use longitudinal data from the German LifE-Study, which focuses on the birth cohort of individuals born between 1965 and 1967. Using event history analysis, we find that the timing of the first sexual experience and first partnership transitions are mainly influenced by personal and social ressources, whereas socio-economic resources offer better explanations for the timing of entering marriage and parenthood. Most striking are the different explanatory models for women and men

Vertical mixing in pelagic sediments

Vertical mixing in sed iments can be quantitatively described if it is assumed that: (i) upon deposition, detrital particles are mixed uniformly to a depth, m, below the sediment-water interface at a rate that is much faster than the sedimentation rate

Predicting the Timing of Social Transitions from Personal, Social and Socio-Economic Resources of German Adolescents

Social transitions are characterized by an increased heterogeneity in Western societies. Following the life course perspective, individual agency becomes central in shaping one’s life course. This article examines social transitions of adolescents using individual resource theory to explain differences of the timing of five transitions in partnership and family formation: the first sexual experience, the first intimate relationship, the first cohabitation, the first marriage, and the birth of the first child. Since little is so far known about how individual characteristics interact and influence the social transition to adulthood, we focus on the varying impacts of personal, social and socio-economic resources across the social life course. We use longitudinal data from the German LifE-Study, which focuses on the birth cohort of individuals born between 1965 and 1967. Using event history analysis, we find that the timing of the first sexual experience and first partnership transitions are mainly influenced by personal and social ressources, whereas socio-economic resources offer better explanations for the timing of entering marriage and parenthood. Most striking are the different explanatory models for women and men