Economic production and, more generally, most global societies, are overwhelmingly dependant upon depleting supplies of fossil fuels. There is considerable concern amongst resource scientists, if not most economists, as to whether market signals or cost benefit analysis based on today's prices are sufficient to guide our decisions about our energy future. These suspicions and concerns were escalated during the oil price increase from 2005 -2008 and the subsequent but probably related market collapse of 2008. We believe that Energy Return On Investment (EROI) analysis provides a useful approach for examining disadvantages and advantages of different fuels and also offers the possibility to look into the future in ways that markets seem unable to do. The goal of this paper is to review the application of EROI theory to both natural and economic realms, and to assess preliminarily the minimum EROI that a society must attain from its energy exploitation to support continued economic activity and social function. In doing so we calculate herein a basic first attempt at the minimum EROI for current society and some of the consequences when that minimum is approached. The theory of the minimum EROI discussed here, which describes the somewhat obvious but nonetheless important idea that for any being or system to survive or grow it must gain substantially more energy than it uses in obtaining that energy, may be especially important. Thus any particular being or system must abide by a "Law of Minimum EROI", which we calculate for both oil and corn-based ethanol as about 3:1 at the mine-mouth/farm-gate. Since most biofuels have EROI's of less than 3:1 they must be subsidized by fossil fuels to be useful.

Context Recent studies of inhaled corticosteroid (ICS) therapy for managing stable chronic obstructive pulmonary disease (COPD) have yielded conflicting results regarding survival and risk of adverse events. Objective To systematically review and quantitatively synthesize the effects of ICS therapy on mortality and adverse events in patients with stable COPD. Data Sources Search of MEDLINE, CENTRAL, EMBASE, CINAHL, Web of Science, and PsychInfo through February 9, 2008. Study Selection Eligible studies were double-blind, randomized controlled trials comparing ICS therapy for 6 or more months with nonsteroid inhaled therapy in patients with COPD. Data Extraction Two authors independently abstracted data including study characteristics, all-cause mortality, pneumonia, and bone fractures. The I2 statistic was used to assess heterogeneity. Study-level data were pooled using a random-effects model (when I2≥50%) or a fixed-effects model (when I2<50%). For the primary outcome of all-cause mortality at 1 year, our meta-analysis was powered to detect a 1.0% absolute difference in mortality, assuming a 2-sided α of .05 and power of 0.80. Results Eleven eligible randomized controlled trials (14 426 participants) were included. In trials with mortality data, no difference was observed in 1-year all-cause mortality (128 deaths among 4636 patients in the treatment group and 148 deaths among 4597 patients in the control group; relative risk [RR], 0.86; 95% confidence interval [CI], 0.68–1.09; P=.20; I2=0%). In the trials with data on pneumonia, ICS therapy was associated with a significantly higher incidence of pneumonia (777 cases among 5405 patients in the treatment group and 561 cases among 5371 patients in the control group; RR, 1.34; 95% CI, 1.03–1.75; P=.03; I2=72%). Subgroup analyses indicated an increased risk of pneumonia in the following subgroups: highest ICS dose (RR, 1.46; 95% CI, 1.10–1.92; P=.008; I2=78%), shorter duration of ICS use (RR, 2.12; 95% CI, 1.47–3.05; P<.001; I2=0%), lowest baseline forced expiratory volume in the first second of expiration (RR, 1.90; 95% CI, 1.26–2.85; P=.002; I2=0%), and combined ICS and bronchodilator therapy (RR, 1.57; 95% CI, 1.35–1.82; P<.001; I2=24%). Conclusions Among patients with COPD, ICS therapy does not affect 1-year all-cause mortality. ICS therapy is associated with a higher risk of pneumonia. Future studies should determine whether specific subsets of patients with COPD benefit from ICS therapy.

There have been five foremost empirical efforts regarding energy return on investment (EROI) analysis over the past few years, including the topics of: (1) whether corn ethanol is a net energy yielder; (2) a summary of the state of EROI for most major fuel types; (3) alternative applications of EROI, such as energy return on water invested (EROWI); (4) the relation between EROI and the economy; and (5) an attempt to calculate the minimum EROI for a sustainable society. This paper offers a review of these five main areas of interest and provides a history of the development of EROI as well as a review of some of the various definitions of EROI and how they apply to EROI analyses. The paper concludes by listing numerous areas of improvement that are needed within EROI research.