Time-varying retail electricity pricing is very popular with economists, but has little support among regulators and consumers. I propose an opt-in time-varying residential pricing plan that would be ...equitable to both customers who opt in and those who don't. Low-income households would, on average, see almost no change in their bills under time-varying pricing, while low-consumption households would see their bills decline somewhat and high-consumption households would see their bills rise. Most importantly, I show that the opt-in approach is unlikely to increase the flat rate charged to other customers by more than a few percentage points.
We present a method for decomposing wholesale electricity payments into production costs, inframarginal competitive rents, and payments resulting from the exercise of market power. Using data from ...June 1998 to October 2000 in California, we find significant departures from competitive pricing during the high-demand summer months and near-competitive pricing during the lower-demand months of the first two years. In summer 2000, wholesale electricity expenditures were $8.98 billion up from $2.04 billion in summer 1999. We find that 21 percent of this increase was due to production costs, 20 percent to competitive rents, and 59 percent to market power.
Despite the key role of γ-aminobutyric acid (GABA) neurons in the modulation of cerebral cortical output, little is known about their development in the human cortex. We analyzed several GABAergic ...parameters in standardized regions of the cerebral cortex and white matter in a total of 38 human fetuses and infants from 19 gestational weeks to 2.7 postnatal years using immunocytochemistry, Western blotting, tissue autoradiography, and computer-based cellular quantitation. At least 20% of GABAergic neurons in the white matter migrated toward the cortex over late gestation. After term, migration declined and ended within 6 postnatal months. In parallel, the GABAergic neuronal density increased in the cortex over late gestation, also with a peak at term. From midgestation to infancy, the pattern of GABAA receptor binding changed from uniformly low across all cortical layers to high levels concentrated in the middle laminae; glutamic acid decarboxylase (GAD65 and GAD67) levels differentially increased. Thus, the second half of gestation is a period of rapid development of the cortical GABAergic system that continues into early infancy. This period corresponds to the peak window of vulnerability to perinatal hypoxia-ischemia in which GABAergic neurons are potentially developmentally susceptible, including in the preterm infant.
Hypoxic-ischemic injury to the periventricular cerebral white matter periventricular leukomalacia (PVL) results in cerebral palsy and is the leading cause of brain injury in premature infants. The ...principal feature of PVL is a chronic disturbance of myelination and suggests that oligodendrocyte (OL) lineage progression is disrupted by ischemic injury. We determined the OL lineage stages at risk for injury during the developmental window of vulnerability for PVL (23-32 weeks, postconceptional age). In 26 normal control autopsy human brains, OL lineage progression was defined in parietal white matter, a region of predilection for PVL. Three successive OL stages, the late OL progenitor, the immature OL, and the mature OL, were characterized between 18 and 41 weeks with anti-NG2 proteoglycan, O4, O1, and anti-myelin basic protein (anti-MBP) antibodies. NG2+O4+ late OL progenitors were the predominant stage throughout the latter half of gestation. Between 18 and 27 weeks, O4+O1+ immature OLs were a minor population (9.9 +/- 2.1% of total OLs; n = 9). Between 28 and 41 weeks, an increase in immature OLs to 30.9 +/- 2.1% of total OLs (n = 9) was accompanied by a progressive increase in MBP+ myelin sheaths that were restricted to the periventricular white matter. The developmental window of high risk for PVL thus precedes the onset of myelination and identifies the late OL progenitor as the major potential target. Moreover, the decline in incidence of PVL at approximately 32 weeks coincides with the onset of myelination in the periventricular white matter and suggests that the risk for PVL is related to the presence of late OL progenitors in the periventricular white matter.
Background: Heterotaxia syndrome involves multiple anomalies, including cardiac malformations and intestinal rotation abnormalities. Most authors recommend routine radiological evaluation, with ...laparotomy and Ladd procedure if a rotation abnormality is found. Aims: To determine if routine radiological screening is necessary, and if there is a group of children that can safely be managed expectantly. Methods: Retrospective chart review of all children with heterotaxia syndrome from 1968 to 2002. Results: Complete data were available for 177 patients. Twenty five (14%) had neonatal gastrointestinal symptoms (feeding intolerance, vomiting). Eleven of these had gastrointestinal contrast studies, of which seven were abnormal and led to surgery. Of the 152 asymptomatic neonates, nine had radiological screening and six of these were abnormal. Only one was thought to have a narrow based mesentery, but did not undergo surgery due to cardiac disease. There were no intestinal complications on follow up in this group. The other 143 asymptomatic children did not undergo radiological screening and were closely followed. Four subsequently developed gastrointestinal symptoms and had contrast studies; only one of these had malrotation and underwent a Ladd procedure. Of the remaining 139 patients who remained asymptomatic, 60 (43%) died of cardiac disease and none developed intestinal symptoms or complications related to malrotation on follow up. Conclusion: Asymptomatic children with heterotaxia syndrome have a low risk of adverse outcome related to intestinal rotation abnormalities. Routine screening may not be necessary as long as close follow up is done, and prompt investigation is performed for those that develop gastrointestinal symptomatology.
We test and confirm that retail gasoline prices respond more quickly to increases than to decreases in crude oil prices. Among the possible sources of this asymmetry are production/inventory ...adjustment lags and market power of some sellers. By analyzing price transmission at different points in the distribution chain, we attempt to shed light on these theories. Spot prices for generic gasoline show asymmetry in responding to crude oil price changes, which may reflect inventory adjustment effects. Asymmetry also appears in the response of retail prices to wholesale price changes, possibly indicating short-run market power among retailers.
Periventricular leukomalacia (PVL) involves free radical injury to developing oligodendrocytes (OLs), resulting from ischemia/reperfusion, particularly between 24 and 32 gestational weeks. Using ...immunocytochemistry and Western blots, we tested the hypothesis that this vulnerability to free radical toxicity results, in part, from developmental lack of superoxide dismutases (SOD)-1 and -2, catalase, and glutathione peroxidase (GPx) in the telencephalic white matter of the human fetus. During the period of greatest PVL risk and through term (≥37 weeks), expression of both SODs (for conversion of O2 to H2O2) significantly lagged behind that of catalase and GPx (for breakdown of H2O2), which, in contrast, superseded adult levels by 30 gestational weeks. Our data indicate that a developmental “mismatch” in the sequential antioxidant enzyme cascade likely contributes to the vulnerability to free radical toxicity of the immature cerebral white matter, which is “unprepared” for the transition from a hypoxic intrauterine to an oxygen-rich postnatal environment. All enzymes, localized to astrocytes and OLs, had higher-than-adult expression at 2 to 5 postnatal months (peak of myelin sheath synthesis), suggesting an adaptive mechanism to protect against lipid peroxidation during myelin sheath (lipid) synthesis. The previously unrecognized dissociation between the expression of the SODs and that of catalase and GPx in the fetal period has potential implications for future antioxidant therapy in PVL.
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