RESUMEN
We theoretically demonstrate the coherent control of the effective susceptibility of a duplicated two-level system. The control is obtained for a linearly polarized weak field in the presence of a much stronger orthogonally polarized field. For small optical depths, the effective susceptibility chi(eff) behaves as chilin(e 2iphi) (chilin) is the linear susceptibility, phi the phase shift) allowing coherent control of the optical response. For large optical depths, chi(eff) approximately chi(lin), turning an absorber into an amplifier without affecting the dispersion.
RESUMEN
To determine, in non-diabetic women, the relationship of abnormal glucose screening test, with the incidence of pre-eclampsia, macrosomia and caesarian delivery, from 1988-92, 5646 consecutive women attending antenatal clinic were screened with a glucose challenge test (GCT) on their first visit (usually at 16-20 weeks); those with risk factors i.e., history of unexplained perinatal loss, macrosomia or family member with diabetes and an initial abnormal screening test were rescreened at 28-32 weeks. In 482 cases the GCT was abnormal (plasma glucose value was > 140 mg% 2 hours after 75 g glucose challenge). Of these, 292 had one or more abnormal critical values at a 75 g-3 hour oral glucose tolerance test (GTT) and they were treated to maintain euglycaemia. The rest (n = 190) had no evidence of glucose intolerance with no abnormal values at the GTT. The subjects were divided into 3 groups based on GCT values; A, randomly selected subjects with a normal GCT (n = 1000); B, those with abnormal GCT but normal GTT (n = 190); and C, those with abnormal GTT (n = 292). The variables studied were age, gravidity, parity, gestational age at delivery, pre-eclampsia, birth-weight and mode of delivery. The incidence of pre-eclampsia and caesarian birth varied, being the lowest in Group A (3.9% and 11.9% respectively) and then rising through group B (6.3% and 16.3% respectively) to the highest in Group C (12.6% and 26.0% respectively; test of linear trend, p < 0.05). For macrosomia, the incidence increased from Group A to B but there was a drop in Group C.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Cesárea , Macrosomía Fetal/prevención & control , Hiperglucemia/complicaciones , Preeclampsia/prevención & control , Complicaciones del Embarazo , Complicaciones del Embarazo/prevención & control , Adulto , Análisis de Varianza , Distribución de Chi-Cuadrado , Femenino , Macrosomía Fetal/sangre , Prueba de Tolerancia a la Glucosa/métodos , Humanos , Hiperglucemia/sangre , Modelos Lineales , Pakistán/epidemiología , Preeclampsia/sangre , Embarazo , Complicaciones del Embarazo/sangre , Sensibilidad y EspecificidadRESUMEN
We determined in nondiabetic women, the relationship of plasma glucose values obtained 2 hours after a 75 g oral glucose challenge test (GCT) at 16-20 weeks' gestation, with the incidence of macrosomia in term deliveries (37-41 weeks' gestation). From 1988-1990, in a systematic screening programme data collected prospectively from 1,331 women were analysed retrospectively. Women with gestational diabetes or impaired glucose tolerance (n = 53) were excluded. The rest (n = 1,278) had no evidence of glucose intolerance including 1,215 women with normal plasma glucose by GCT (< 7.8 mmol/L 2 hours after 75 g oral glucose load) and 63 women with abnormal GCT but not abnormal value at a glucose tolerance test. The GCT values were divided into 5 groups: Group A (< 4.5 mmol/L), B (4.5-5.5 mmol/L), C (5.6-6.6 mmol/L), D (6.7-7.7 mmol/L) and E (> 7.8 mmol/L). The variables studied were age, parity, gestational age at delivery and incidence of macrosomia. Using > 4 kg birth-weight as the definition of macrosomia, the incidence increased from 1.2% to 9.5% with increasing plasma glucose values in the GCT from Group A (> 4.5 mmol/L) to E (> 7.8 mmol/L). Similar trends of increasing incidences from 7.2% to 15.8% and 2.9% to 9.5% were noted when 90th and 95th birth-weight percentiles, respectively were used as definitions of macrosomia. The test of linear trend in this association was significant (p < 0.01). These results were not influenced by parity or gestational age at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)