850 research outputs found
Competition Without Chaos
California heralded the New Year with a wave of rolling blackouts, spiraling wholesale electricity prices, and at least one utility bankruptcy. California, which symbolizes the electronic age and represents an eighth of the U.S. economy and its population, faces electricity supply issues not seen since the Great Depression and the collapse of the great utility holding companies. To what extent is California the bellwether for the restructured electric industry in the United States? We do not believe that the recent crisis in California is a signal that competition and deregulation have failed. Indeed, it remains our firm belief that market-oriented restructuring of the electric industry remains the best opportunity to provide consumer benefits and to develop reliable new sources of supply. After all, a major impetus for introducing competition into the generation and marketing of electricity has been the previous failures in long-term planning decisions made by public utilities and their regulators. The regulated monopoly regime simply did not provide the correct economic incentives for a company to provide electric service efficiently. To what extent can other states that have restructured their electric industries expect to see California-like dramatic sustained price increases and supply shortages resulting in rolling blackouts? The root cause of California's problems was its long-term failure to build generating plants during the most sustained economic boom in the state's history. California's most significant restructuring problem was also a local issue. The California restructuring law required utilities collecting stranded costs to retain fixed price obligations to retail customers, while preventing them from hedging their price risk in the wholesale market by entering into long-term supply contracts. The California market design flaws have been avoided in the restructuring legislation enacted by the twenty-four states and the District of Columbia that have restructured electricity markets. Among these states are Pennsylvania and Illinois, the states where Exelon conducts public utility businesses. The restructuring efforts in these other states are generally yielding results quite different from those in California and demonstrate that thoughtful, market-oriented, evolutionary restructuring can work well for all parties. This is not a reason, however, for complacency. Government agencies, utilities and all market stakeholders must work hard to make sure this answer remains valid a few years hence. This work includes establishing appropriate pricing and incentives to encourage the building of new supply and the development of demand-side management programs; establishing regional transmission organizations in order to support the expansion of and appropriate pricing for transmission; establishing appropriate rules and pricing regarding the utilities provider of last resort or default supply obligation. The default supply issue is one of the most significant challenges to the transition to competition. If the delivery companies retain primary responsibility for arranging supply and thus lock up most of the generation sources, the result is reliable service and stable rates for customers. However, new market entrants' access to supply sources will be limited and at high prices, making it difficult for them to compete. To resolve this dilemma, we propose a bifurcated approach to default service offerings and pricing. For large customers, who have the most desirable service characteristics to competitive suppliers and thus more opportunity to hedge their price risk, the utilities' only default service obligation would be unbundled energy at a market price. For mass market customers, who lack hedging ability because of limited, if any, market development, the utilities would provide a fixed price, multi-year energy supply offering. The price for both offerings must include a risk premium adequate to compensate the utility for the risk it assumes and to avoid rates that are too low to allow alternative suppliers to compete. We believe our default supply resolution will achieve the competing goals of price stability, reliability, and the development of a mature competitive market. The California experience is not an accident or the product of bad luck. It is the product of choices, long-term choices about siting generation and transmission, and the more recent choice of a market design that imposed asymmetric risks on utilities to the ultimate detriment of all. If other states make similar choices, similar consequences can be expected to follow. In short, the California experience is no reason to reject restructuring; it is rather a forceful lesson on the importance of doing it right.
An unusual case of peripartum cardiomyopathy manifesting with multiple thrombo-embolic phenomena
Peripartum cardiomyopathy (PPCM) is a rare form of heart failure with a reported incidence of 1 per 3000 to 1 per 4000 live births and a fatality rate of 20%–50%. Onset is usually between the last month of pregnancy and up to 5 months postpartum in previously healthy women. Although viral, autoimmune and idiopathic factors may be contributory, its etiology remains unknown. PPCM initially presents with signs and symptoms of congestive heart failure and rarely with thrombo-embolic complications. We report an unusual case of PPCM in a previously healthy postpartum woman who presented with an acute abdomen due to unrecognized thromboemboli of the abdominal organs. This case illustrates that abdominal pain in PPCM may not always result from hepatic congestion as previously reported, but may occur as a result of thromboemboli to abdominal organs. Further research is needed to determine the true incidence of thromboemboli in PPCM
MANCHESTER (Reino Unido). Planos de población (1794). 1:2200
Comprende los planos de las ciudades mencionadas y sus alrededores, habiendo sido englobada en la actualidad Salford por ManchesterEscala gráfica de 440 yardas o 1/4 de milla [= 18,8 cm]. Orientado con lis en cuadrante de orientaciónOrografía a trazosToponimia de las principales calles y plazas de la ciudad, así como de sus edificios más representativosLocaliza las haciendas de los alrededores, indicando los hombres de sus propietariosTítulo enmarcado en escena alegórica sobre la riqueza de Manchester (Fortuna derramando monedas sobre tres puttique le presenta el plano de la misma, figurándo al fondo el edificio de una fábrica)Forma parte de la Colección Mendoz
Rasch analysis of the hospital anxiety and depression scale (hads) for use in motor neurone disease
<p>Abstract</p> <p>Background</p> <p>The Hospital Anxiety and Depression Scale (HADS) is commonly used to assess symptoms of anxiety and depression in motor neurone disease (MND). The measure has never been specifically validated for use within this population, despite questions raised about the scale's validity. This study seeks to analyse the construct validity of the HADS in MND by fitting its data to the Rasch model.</p> <p>Methods</p> <p>The scale was administered to 298 patients with MND. Scale assessment included model fit, differential item functioning (DIF), unidimensionality, local dependency and category threshold analysis.</p> <p>Results</p> <p>Rasch analyses were carried out on the HADS total score as well as depression and anxiety subscales (HADS-T, D and A respectively). After removing one item from both of the seven item scales, it was possible to produce modified HADS-A and HADS-D scales which fit the Rasch model. An 11-item higher-order HADS-T total scale was found to fit the Rasch model following the removal of one further item.</p> <p>Conclusion</p> <p>Our results suggest that a modified HADS-A and HADS-D are unidimensional, free of DIF and have good fit to the Rasch model in this population. As such they are suitable for use in MND clinics or research. The use of the modified HADS-T as a higher-order measure of psychological distress was supported by our data. Revised cut-off points are given for the modified HADS-A and HADS-D subscales.</p
Cardiovascular and inflammatory effects of simvastatin therapy in patients with COPD: a randomized controlled trial.
BACKGROUND:
There is excess cardiovascular mortality in patients with chronic obstructive pulmonary disease. Aortic stiffness, an independent predictor of cardiovascular risk, and systemic and airway inflammation are increased in patients with the disease. Statins modulate aortic stiffness and have anti-inflammatory properties. A proof-of-principle, double-blind, randomized trial determined if 6 weeks of simvastatin 20 mg once daily reduced aortic stiffness and systemic and airway inflammation in patients with chronic obstructive pulmonary disease.
METHODS:
Stable patients (n=70) were randomized to simvastatin (active) or placebo. Pre-treatment and post-treatment aortic stiffness, blood pressure, spirometry, and circulating and airway inflammatory mediators and lipids were measured. A predefined subgroup analysis was performed where baseline aortic pulse wave velocity (PWV) was >10 m/sec.
RESULTS:
Total cholesterol dropped in the active group. There was no significant change in aortic PWV between the active group and the placebo group (-0.7 m/sec, P=0.24). In those with aortic stiffness >10 m/sec (n=22), aortic PWV improved in the active group compared with the placebo group (-2.8 m/sec, P=0.03). Neither systemic nor airway inflammatory markers changed.
CONCLUSION:
There was a nonsignificant improvement in aortic PWV in those taking simvastatin 20 mg compared with placebo, but in those with higher baseline aortic stiffness (a higher risk group) a significant and clinically relevant reduction in PWV was shown
Mapping preictal and ictal haemodynamic networks using video-electroencephalography and functional imaging
Ictal patterns on scalp-electroencephalography are often visible only after propagation, therefore rendering localization of the seizure onset zone challenging. We hypothesized that mapping haemodynamic changes before and during seizures using simultaneous video-electroencephalography and functional imaging will improve the localization of the seizure onset zone. Fifty-five patients with ≥2 refractory focal seizures/day, and who had undergone long-term video-electroencephalography monitoring were included in the study. ‘Preictal' (30 s immediately preceding the electrographic seizure onset) and ictal phases, ‘ictal-onset'; ‘ictalestablished' and ‘late ictal', were defined based on the evolution of the electrographic pattern and clinical semiology. The functional imaging data were analysed using statistical parametric mapping to map ictal phase-related haemodynamic changes consistent across seizures. The resulting haemodynamic maps were overlaid on co-registered anatomical scans, and the spatial concordance with the presumed and invasively defined seizure onset zone was determined. Twenty patients had typical seizures during functional imaging. Seizures were identified on video-electroencephalography in 15 of 20, on electroencephalography alone in two and on video alone in three patients. All patients showed significant ictal-related haemodynamic changes. In the six cases that underwent invasive evaluation, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure onset zone for all patients. The most statistically significant haemodynamic cluster within the presumed seizure onset zone was between 1.1 and 3.5 cm from the invasively defined seizure onset zone, which was resected in two of three patients undergoing surgery (Class I post-surgical outcome) and was not resected in one patient (Class III post-surgical outcome). In the remaining 14 cases, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure onset zone in six of eight patients with structural-lesions and five of six non-lesional patients. The most statistically significant haemodynamic cluster was localizable at sub-lobar level within the presumed seizure onset zone in six patients. The degree of concordance of haemodynamic maps was significantly better (P < 0.05) for the ictal-onset phase [entirely concordant/concordant plus (13/20; 65%) + some concordance (4/20; 20%) = 17/20; 85%] than ictal-established [entirely concordant/concordant plus (5/13; 38%) + some concordance (4/13; 31%) = 9/13; 69%] and late ictal [concordant plus (1/9; 11%) + some concordance (4/9; 44%) = 5/9; 55%] phases. Ictal propagation-related haemodynamic changes were also seen in symptomatogenic areas (9/20; 45%) and the default mode network (13/20; 65%). A common pattern of preictal changes was seen in 15 patients, starting between 98 and 14 s before electrographic seizure onset, and the maps had a degree of concordance with the presumed seizure onset zone in 10 patients. In conclusion, preictal and ictal haemodynamic changes in refractory focal seizures can non-invasively localize seizure onset at sub-lobar/gyral level when ictal scalp-electroencephalography is not helpfu
A metal-organic framework with ultrahigh glass-forming ability
Glass-forming ability (GFA) is the ability of a liquid to avoid crystallization during cooling. Metal-organic frameworks (MOFs) are a new class of glass formers (1?3), with hitherto unknown dynamic and thermodynamic properties. We report the discovery of a new series of tetrahedral glass systems, zeolitic imidazolate framework?62 (ZIF-62) [Zn(Im2?xbImx)], which have ultrahigh GFA, superior to any other known glass formers. This ultrahigh GFA is evidenced by a high viscosity ? (105 Pa?s) at the melting temperature Tm, a large crystal-glass network density deficit (??/?g)network, no crystallization in supercooled region on laboratory time scales, a low fragility (m = 23), an extremely high Poisson?s ratio (? = 0.45), and the highest Tg/Tm ratio (0.84) ever reported. Tm and Tg both increase with benzimidazolate (bIm) content but retain the same ultrahigh Tg/Tm ratio, owing to high steric hindrance and frustrated network dynamics and also to the unusually low enthalpy and entropy typical of the soft and flexible nature of MOFs. On the basis of these versatile properties, we explain the exceptional GFA of the ZIF-62 systempublishersversionPeer reviewe
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