Spatially and Temporally Resolved Analysis of Environmental Trade-Offs in Electricity Generation.

The US power sector is a leading contributor of emissions that affect air quality and climate. It also requires a lot of water for cooling thermoelectric power plants. Although these impacts affect ecosystems and human health unevenly in space and time, there has been very little quantification of these environmental trade-offs on decision-relevant scales. This work quantifies hourly water consumption, emissions (i.e., carbon dioxide, nitrogen oxides, and sulfur oxides), and marginal heat rates for 252 electricity generating units (EGUs) in the Electric Reliability Council of Texas (ERCOT) region in 2011 using a unit commitment and dispatch model (UC&D). Annual, seasonal, and daily variations, as well as spatial variability are assessed. When normalized over the grid, hourly average emissions and water consumption intensities (i.e., output per MWh) are found to be highest when electricity demand is the lowest, as baseload EGUs tend to be the most water and emissions intensive. Results suggest that a large fraction of emissions and water consumption are caused by a small number of power plants, mainly baseload coal-fired generators. Replacing 8-10 existing power plants with modern natural gas combined cycle units would result in reductions of 19-29%, 51-55%, 60-62%, and 13-27% in CO2 emissions, NOx emissions, SOx emissions, and water consumption, respectively, across the ERCOT region for two different conversion scenarios.

Spinal Pleomorphic Xanthoastrocytoma: Case Report and Literature Review.

Pleomorphic xanthoastrocytoma (PXA) is an uncommon central nervous system neoplasm with an overall favorable survival prognosis. Metastatic spread of PXA to the spinal cord and the cauda equina is rare and may have a different clinicopathologic course. Treatment and prognostic outcomes, in this context, are not well defined. We discuss a case of a 30-year-old patient with known cerebral PXA presenting with metastatic spinal anaplastic PXA and present a literature analysis of treatment outcomes.

Brainstem distortion from postoperative cerebellar herniation through a dural and bony defect.

We report a patient with a cerebellar encephalocele following excision of a cerebellar metastasis. This is a life-threatening condition that may be prevented with adequate dural and bony closure.

Interobserver Reliability of Spinal Adverse Events Severity System - Neuro (SAVES-N): A Prospective Adverse Event Reporting System for Neurosurgical Cases.

BACKGROUND: The reporting of adverse events (AEs) in neurosurgery uses inconsistent definitions and subjective grading systems. A standardized system for recording and describing AEs would allow valid comparisons to be drawn between different institutions, using different technologies, at different times. The Spinal Adverse Events Severity System - Neuro (SAVES-N) system is a modification of the well-validated SAVES-V2 system that encompasses complications from both cranial and spinal surgery. The objective of this study was to assess the interobserver reliability of SAVES-N in spinal and cranial neurosurgery. METHODS: Ten vignettes, including cranial and spinal neurosurgical cases, were assessed by groups of consultant neurosurgeons (n = 5) and neurosurgical registrars (n = 5) using the SAVES-N system. Interobserver reliability for the presence of AEs, the type of AE, and the SAVES severity grade of the AE were calculated using Gwet's AC2 and Fleiss' kappa and were interpreted using the thresholds described by Landis and Koch. RESULTS: Neurosurgeons had almost-perfect agreement (Gwet AC2 = 0.93), whereas registrars had substantial agreement (Gwet's AC2 = 0.74) in determining the presence or absence of AEs. Both neurosurgeons (Fleiss' kappa = 0.78) and registrars (Fleiss' kappa = 0.70) demonstrated substantial agreement within their groups as to the type of AE. Similarly, neurosurgeons (Gwet's AC2 = 0.94) and registrars (Gwet's AC2 = 0.81) both graded the severity of the AE with almost perfect agreement. CONCLUSIONS: The results of this study demonstrate that the scope of the well-validated SAVES-V2 system may be broadened to cranial neurosurgical cases by SAVES-N with substantial to almost-perfect interobserver reliability.

Cerebellar astrocytoma presenting with precocious puberty in a girl. Case report.

Central precocious puberty in girls is uncommon and tends to be idiopathic in most cases. In about 20 to 30% of cases there is an intracranial mass lesion. The common lesions are hypothalamic hamartomas, optic nerve gliomas, suprasellar arachnoid cysts, hydrocephalus, germinomas, and other sellar/suprasellar lesions. Central precocious puberty secondary to a cerebellar astrocytoma is extremely rare. The authors report the first case in a girl who presented with several episodes of bleeding per vaginum. There was no clinical or radiological evidence of raised intracranial pressure.