A thermodynamic model is presented to describe the combined freezing and thawing process for living cells. Continuous changes in the cell volume are predicted according to the thermal protocol imposed on the system. Experimental verification of the model is sought by monitoring continuously the volume of cells as frozen on a cryomicroscope. The volumes of individual cells are measured from sequential photomicrographs by a computerized image analysis technique. The model and experimental data are in quite close agreement for the freezing process, but upon thawing the experimentally measured volumes consistently increased much more rapidly than predicted by the model. The model can be made to conform to the data by accounting for a substantial influx of electrolyte to the cell at subfreezing temperatures.

Plasma beta-endorphin (BE) levels (8.6 +/- 0.8 pmol/l) (mean +/- SE) were lower in the third trimester than in non-pregnant controls (14.8 +/- 1.1 pmol/l) (P less than 0.001), increased during labor, to 29.3 +/- 4.4 pmol/l (P less than 0.005) and decreased, 72 h after delivery, to 3.5 +/- 0.4 pmol/l (P less than 0.001). BE levels were found to correlate significantly with uterine muscle contraction (r = 0.966, P less than 0.05) and with cervical effacement (r = 0.974, P less than 0.05) during labor.

The police in several Western countries have been the object of a good deal of dissatisfaction lately, whether in open confrontation with rioters and demonstrators, or as the object of severe criticism by the courts and civilian review boards. Since the respect and cooperation of the public are essential for effective police operation–in reporting crimes, assisting officers, testifying in court, or in less direct ways–police departments have begun to turn their attention to the sources of this tension. Simultaneously, this problem has become a focus of study for a number of social scientists (see, for example, Banton, 1964; Bordua, 1967; Cumming et al., 1965; Gardiner, 1969; Goldstein, 1963; Gourley, 1954; Skolnick, 1966; and Wilson, 1968). We have undertaken a study of some aspects of the relationship between the police and the public in Israel, in the context of a wider series of studies on patterns of contact between bureaucratic organizations and their clients. There may be factors in this relationship which are not evident in other countries; for example, Israeli police are organized on a national basis with centralized control rather than by local departments as in the American system, and the Israeli police are integrated with the national security effort. These very differences, however, may clarify some fundamental elements of the police-public encounter in general.

Serum creatinine, blood urea nitrogen and creatine phosphokinase were measured in 32 women during the last 3 weeks of pregnancy and, in a further 39 women, during and after labor. The serum creatinine increased from 61.9 +/- 0.9 to 69.8 +/- 1.8 mumol/l (mean +/- SEM) (P less than 0.05) in the third stage of labor and returned to normal by 72 h after delivery. The muscle creatine phosphokinase increased from 54 +/- 7 to 77 +/- 9.9 units (P less than 0.05) during the third stage and remained high (87 +/- 13.3 units) 72 h later. We conclude that these changes are due to muscle contraction and injury during delivery.

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