Caesarean section rates are inexorably rising which has led to the possibility of negative impact on m aternal and neonatal health. Present study was aimed to compare the factors associated with caesarean and vaginal births among pregnant women. A retrospective study was con ducted in Obstetrics and Gynaecology Department, Pu njab Institute of Medical Sciences, Jalandhar (Punjab, Iduring the period of April, 2012 to June, 201 2. Details of age group, parity, socioeconomic status, antenatal booking, mode of delivery, obstetric complications, gestational age at delivery, maternal and neonatal outcomes wer e explored. The prevalence of Caesarean Sections (6 5%) was higher over vaginal births (35%). It had higher num ber of Emergency (52.31%) over Elective (47.70%) ca esarean sections. Multiparity (55.38%; p<0.05), high socioe conomic status (18.46%), 21 to 30 yrs of age group (78.46%) and booked status (44.62%) were associated with Cae sarean Sections while primiparity (65.71%) and low socioeconomic status (22.86%) with vaginal births. The commonest reasons for Caesarean Sections were F etal Distress (30.77%) and Repeat Caesarean Sections (29.23%). Ca esarean sections rate is high. High number of referred patients who underwent Emergency sections was the main reason. Trial of vaginal birth after C aesarean Section in approximate cases and confirmation of su spected fetal distress through fetal blood acid bas e study are recommended.

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CoWO4 is a p-type semiconductor with conductivity in the range 10−8 to 10−3 ohm−1 cm−1. The solid exhibits extrinsic behaviour up to 750 K and intrinsic behaviour above 750 K. In this solid conduction by hopping of small polarons seems to be dominating up to 750 K and above 750 K conduction becomes band type. The energy band gap of the solid has been found to be 2.80 eV. The values of mobility and the mean free path are estimated. The variation of dielectric constant with temperature has been attributed to changes in atomic and ionic polarization and space charge polarization of thermally generated charge carriers.

On electrical transport in CoWO4 single crystals

Measurements of a.c. and d.c. electrical conductivity in crystals of nickel tungstate, in the temperature range 300 to 1100 K, are presented. NiWO4 is found to be a semiconductor with a band gap of 2.10 eV. The nature of the electrical conduction is discussed in the light of various conduction models.

Electrical conductivity of single crystal nickel tungstate

The a.c. electrical conductivity (σ
ac), thermoelectric power (θ) and dielectric constant (e′) of antiferromagnetic NiWO4 are presented. σ
ac and e′ have been measured in the temperature range 300 to 1000 K and θ in the temperature range 600 to 1000 K. Conductivity data are interpreted in the light of band theory of solids. The compound obeys the exponential law of conductivity σ=σ
0 exp (−W/kT). Activation energy has been estimated as 0.75eV. The conductivity result is summarized in the following equation σ=2.86 exp (−0.75 eV/kT)Ω−1 cm−1 in the intrinsic region. The material is p-type below 660 K and above 950 K, and is n-type between 660 and 950 K.

Aaron Wold

Papers

Book reviewElectrical conduction in solid materials: J.P. Suchet, Vol. 9. 224 pp., 98 illus. 534 x 814in., Pergamon Press, Oxford, 1975, Price $14.00.