Congruently melting compounds of CaF2 · rcRF3: Part II

Crystals of congruently melting CaF₂ · r_cRF₃, where R = Gd, Tb, Dy, Ho, Y and Er, were shown to have the tysonite (LaF₃-type) structure. From the lattice constants, crystal composition (r_c) and density (p), these compounds are seen to be an extended form of the hexagonal (tysonite) structure of the corresponding RF₃. In these compounds, Ca²⁺ enters substitutionally compensated by a fluoride ion vacancy. The partial molar volume of RF₃ in the compound is a constant of the class of R and equals 37.6 cm³.     

The quality of mother–infant attachment and its relationship to toddlers' initial sociability with peers.

37 age- and sex-matched toddler dyads were observed between ages 20 and 23 mo in a 30-min play session with mothers present. Assignment to dyad was determined by attachment classification, assessed at 18 mo in the M. D. Ainsworth et al (1978) Strange Situation procedure. Ss classified as securely attached (SAs), anxiously avoidant (AAs), or anxiously resistant (ARs) were paired with SAs. In the play situation, SAs were more sociable and more positively oriented toward both mother and peer. Mothers of SAs were more supportive and appropriately directive and played an important role in successful outcomes for their children. AAs participated actively in the play session but were rated as more negative in their orientation toward both mother and peer. ARs appeared highly stressed by this situation; they ignored most peer offers and were most negative toward their mothers. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stearoyl paratoluenesulfonate. A powerful acylating agent for lipid synthesis

The utility of the mixed carboxylic-sulfonic acid anhydride stearoyl p-toluenesulfonate as a powerful, mild acylating agent for lipid synthesis is shown by the synthesis of rac 1,2-distearoyl-3-iodopropane, lecithin and a spin-labeled choline derivative from the corresponding alcohols. The method constitutes a significant improvement of earlier acylating methods.     

Acupuncture analgesia and cesarean section

The application of acupuncture anesthesia in obstetrics is discussed and reviewed. Of 14 patients delivered by cesarean section under acupuncture, 8 (57%) felt no pain, and 6 did not go through the entire procedure without other supplementary anesthesia. The failure and success rates are reviewed. It is suggested that the technique be evaluated further because with acupuncture the fetus and mother are completely protected from the secondary effects of general regional anesthesia.     

Condiciones suficientes para la existencia de solucion optima en un programa semi-infinito

The boundness of the feasible set of a Semi-infinite Programming Problem guarantees, in many cases, the existence of an optimum point. Therefore we study such property in connection with the solution-set of a system of infinitely many constraints. Later on we give existence-theorems for an optimum point, involving the objective function in different ways such as: the generalized Lagrange-function; a specific cone of directions; a special dual problem; and, certain infinite systems associated to the problem.

     

Crystal growth of alkaline earth fluorides in a reactive atmosphere

Crystal growth of MF₂ (M = Ca, Sr, or Ba) is carried out in a reactive atmosphere consisting of HF and a carrier gas (He). Single-crystal Bridgman ingots, with the axis oriented at 〈111〉, are grown up to 5.2 cm in diameter. The mechanical strength of these specimens is found to be higher than what has been reported.     

An examination of exposure control and content balancing restrictions on item selection in CATs using the partial credit model

The purpose of the present investigation was to systematically examine the effectiveness of the Sympson-Hetter technique and rotated content balancing relative to no exposure control and no content rotation conditions in a computerized adaptive testing system (CAT) based on the partial credit model. A series of simulated fixed and variable length CATs were run using two data sets generated to multiple content areas for three sizes of item pools. The 2 (exposure control) X 2 (content rotation) X 2 (test length) X 3 (item pool size) X 2 (data sets) yielded a total of 48 conditions. Results show that while both procedures can be used with no deleterious effect on measurement precision, the gains in exposure control, pool utilization, and item overlap appear quite modest. Difficulties involved with setting the exposure control parameters in small item pools make questionable the utility of the Sympson-Hetter technique with similar item pools.