•The past and future market shares of gases, liquids and solids are analyzed.•Past and future hydrogen/carbon ratio is used as proxy for environmental quality.•Comprehensive estimates of conventional ...and unconventional gas are presented.•Gas supply curves are used to assess economic viability.•We find gas use could increase significantly and help decarbonize the region.
As the Asia Pacific region continues to experience rapid economic growth, natural gas may have an important role in satisfying regional demand and transitioning to a low carbon economy. In this study, a Global Energy Market Model (GEM) is used to analyze the market shares of gases, liquids and solids in the Asia Pacific. The model matches the historical energy mix from 1850 to 2010 as well as the historical hydrogen to carbon (H/C) ratio. The GEM is then used to present scenarios of the Asia Pacific energy mix and H/C ratio to the year 2030. The scenarios vary according to policies and technologies that either encourage or discourage gas use. Estimates of conventional and unconventional gas quantities and costs are also presented, partly with a Variable Shape Distribution Model (VSD) and supply curves. The Asia Pacific is found to have vast natural gas resources, though suitable policies are needed to develop the potential. For instance, incentives will be necessary for investment in gas and LNG technology, as increased market share will not occur if investment does not take place in a timely fashion. In addition, it is important that government intervention not create disincentives for development of the regional gas and LNG industries.
Aperture distribution and spatial arrangement are fundamental characteristics of natural fractures. Since it is impossible to directly measure the aperture of all existing fractures, a power law ...(fractal model) has been commonly used to describe fracture apertures, which has also been extended to estimate fracture spacing and macrofractures density. Although a power law (fractal model) has commonly been used to describe fracture apertures, data points in small and large fracture size ranges tend to deviate from this distribution. In this study, a Variable Shape Distribution (VSD) method was derived from a fractal theory to model fracture size distribution. The VSD method was compared with seven other commonly used models. Eleven fracture datasets collected from five countries on four continents were regressed using these methods. The scale-free methods of the VSD and power law models showed more advantages than the scale-dependent methods. The VSD method was found to best fit all variable aperture size distribution patterns, with an average coefficient of determination of 0.99. The average fractal dimension for all samples calculated by the VSD method (1.36) was slightly higher than that of the power law (1.06). This study is unique in showing that the VSD method can solve a boundary characterization problem that has been widely neglected in previous studies. With the assumption of an even fracture distribution, the VSD method was further applied to estimate average fracture spacing, predict a threshold fracture length that controls the linkage of fractures, and predict fractures outside of the measurement range. This study not only proposes an advanced fractal method to model aperture size distributions in shale and tight rocks but also helps to better understand the importance of fractal dimensions and boundary characterizations.
•Develop Variable Shape Distribution (VSD) method for natural fracture aperture characterization.•Nine models are systematically compared and presented to model twelve fractures samples around the world.•Scale-free methods (VSD and power law) show better regression results than the other methods.•VSD shows the best regression results and solves a boundary problem, widely neglected in previous studies.
•Characterization of conventional, tight, shale and coalbed methane reservoirs.•Variable Shape Distribution model used to estimate global gas quantities.•Gas supply curves used to assess economic ...viability.•Gas is abundant and costs of unconventional production is comparable to conventional.
This paper presents a methodology for connecting endowments, economics and the environment in conventional, tight, shale and Coalbed Methane (CBM) reservoirs. The volumetric estimates are generated by a Variable Shape Distribution model (VSD). The VSD has been shown in the past to be useful for the evaluation of conventional and tight gas reservoirs. However, this is the first paper in which the method is used to also include shale gas and CBM formations. Results indicate a total gas endowment of 70,000tcf, split between 15,000tcf in conventional reservoirs, 15,000tcf in tight gas, 30,000tcf in shale gas and 10,000tcf in CBM reservoirs. Thus, natural gas formations have potential to provide a significant contribution to global energy demand estimated at approximately 790 quads by 2035.
A common thread between unconventional formations is that nearly all of them must be hydraulically fractured to attain commercial production. A significant volume of data indicates that the probabilities of hydraulic fracturing (fracking) fluids and/or methane contaminating ground water through the hydraulically-created fractures are very low. Since fracking has also raised questions about the economic viability of producing unconventional gas in some parts of the world, supply curves are estimated in this paper for the global gas portfolio. The curves show that, in some cases, the costs of producing gas from unconventional reservoirs are comparable to those of conventional gas.
The conclusion is that there is enough natural gas to supply the energy market for nearly 400years at current rates of consumption and 110years with a growth rate in production of 2% per year. With appropriate regulation, this may be done safely, commercially, and in a manner that is more benign to the environment as compared with other fossil fuels.
Concerns about the costs of developing oil and gas from conventional and unconventional formations have led many commentators to assume that increasing prices are in the offing and may be a limiting ...factor for economic growth. Historically, production costs have fluctuated as influenced by the cost-increasing effects of depletion versus the cost-reducing effects of technological progress. This paper aims to review several methods for assessing current and long-term costs. Despite the uncertainty of such estimation, evidence shows that production costs in the foreseeable future might not increase dramatically and actually could decrease as petroleum development methods improve and additional supplies come online. Recent examples include the commercially viable production of unconventional oil and gas resources that has kept energy prices contained.
•Examination of petroleum (oil and gas) production costs.•Methodologies and sources are discussed.•Methods for future cost estimation assessed.•Supply cost curves are estimated for conventional and unconventional petroleum.•Costs may decrease as development methods improve and supplies come online.
Heart failure is associated with frequent hospitalizations, often resulting from volume overload. Measurement of intrathoracic impedance with an implanted device with an audible patient alert may ...detect increases in pulmonary fluid retention early. We hypothesized that early intervention could prevent hospitalizations and affect outcome.
We studied 335 patients with chronic heart failure who had undergone implantation of an implantable cardioverter-defibrillator alone (18%) or with cardiac resynchronization therapy (82%). All devices featured a monitoring tool to track changes in intrathoracic impedance (OptiVol) and other diagnostic parameters. Patients were randomized to have information available to physicians and patients as an audible alert in case of preset threshold crossings (access arm) or not (control arm). The primary end point was a composite of all-cause mortality and heart failure hospitalizations. During 14.9±5.4 months, this occurred in 48 patients (29%) in the access arm and in 33 patients (20%) in the control arm (P=0.063; hazard ratio, 1.52; 95% confidence interval, 0.97-2.37). This was due mainly to more heart failure hospitalizations (hazard ratio, 1.79; 95% confidence interval, 1.08-2.95; P=0.022), whereas the number of deaths was comparable (19 versus 15; P=0.54). The number of outpatient visits was higher in the access arm (250 versus 84; P<0.0001), with relatively more signs of heart failure among control patients during outpatient visits. Although the trial was terminated as a result of slow enrollment, a post hoc futility analysis indicated that a positive result would have been unlikely.
Use of an implantable diagnostic tool to measure intrathoracic impedance with an audible patient alert did not improve outcome and increased heart failure hospitalizations and outpatient visits in heart failure patients. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT 00480077.
The objective of this paper is to assess the potential of natural gas as a transition fuel towards a low- and zero-carbon economy. We use the previously established global energy market model (GEM) ...to first provide a close match of the historical energy mix and the associated carbon levels. The model is then used to make simulations of how the energy mix and carbon quantities would evolve in the long distant future—the year 2150—if past dynamics were an indication of the future. A similar GEM modeling exercise was carried out in a previous work, using historical data up to the year 2005, showing that natural gas would help slow global carbon growth in the next 50–100 years, thus paving the way towards a low carbon future dominated by non-fossil energy use. The present study uses the most recent statistics, from 2005 to 2017, to verify the accuracy of the original GEM projections. Our findings show continued penetration of natural gas in the energy mix until the mid-twenty-first century and an eventual reduction of carbon levels starting around that time.
The role that preprocedural factors have on atrioventricular synchrony (AVS) provided by leadless pacemakers requires investigation.
We aimed to assess the correlation between mitral inflow ...echocardiographic parameters and p-wave morphology with the accelerometer A4 signal amplitude. We also sought to identify clinical and echocardiographic predictors of optimal ambulatory AVS (≥85% of cardiac cycles). Forty-three patients undergoing Micra AV implant from June 2020 to March 2023 were prospectively enrolled. Baseline echocardiogram and 12-lead resting ECG were performed. Device follow-up was scheduled at 24 h, 1, 3, and 6 months and yearly after the implant. Ambulatory AVS was studied with a 24 h Holter monitor performed at 3 months follow-up in 35 patients who remained in VDD mode. A4 signal amplitude at 1 month correlated to peak A wave velocity (r = .376; p = .024) at echocardiogram, but no relationship was found with peak A' wave velocity, E/A, or E'/A' ratio. P-wave amplitude in lead I and aVF correlated to A4 signal amplitude at 1- and 3-months follow-up, respectively. Median AVS during 24 h of daily activities was 85.6 ± 7.6% and remained stable up to 100 bpm. Twenty-three out of 35 patients (65.7%) reached optimal ambulatory AVS. There was no association between mitral inflow echocardiographic parameters and optimal AVS. Diabetes (OR: 0.05, 95% CI: 0.01-0.47; p = .009) and chronic obstructive pulmonary disease (COPD) (OR: 0.06, 95% CI: 0.01-0.63; p = .019) strongly predicted ambulatory AVS <85%.
Diabetes and COPD should be considered when selecting candidates for Micra AV. Measurements of pulsed wave Doppler mitral inflow do not systematically reflect the behavior of the A4 signal amplitude.
This paper compares the global markets for gold and oil so as to explain the surprisingly high correlation of the two materials’ prices since 1970, and the exceedingly impressive rise of both price ...series compared with that of virtually all other primary commodities. We propose that developments in the oil market, and the resulting effects on the macroeconomy, influenced investment activity in gold, thus providing the most plausible explanation for the two commodities’ price synchronization. Our view on the extraordinary price increases of oil and gold, compared to a broad category of metals and minerals, is that oil prices rose first based on above-ground hurdles that restrained the capacity to produce, and gold prices then reacted as they were pushed up by rising safe-haven investment to store value – an attribute not shared by other metals and minerals. The paper also comments on the likely future price evolution of these important materials, arguing that oil prices will stagnate at levels observed from late 2014, or even weaken in the coming decades, but that gold prices will continue to ride relatively high – thus leading to a collapse of the oil/gold price connection.
•We compare markets for gold and oil to explain high correlation of prices since 1970.•Also compare impressive past rise of oil and gold prices vs. other commodities.•Events in oil market and resulting effects on economy influenced gold price.•After oil price rose, gold price was pushed up by rising safe-haven investment.•Oil price will stagnate in coming decades but gold will stay high.•Oil and gold price correlation will collapse.
Hydrogen is expected to play a role in the future low‐carbon economy as an energy carrier, but its market penetration remains to be seen. Much of the existing literature generally focuses on ...comparison of marginal production costs and prices to make rather optimistic projections. This study argues that such analysis is myopic as important barriers are ignored. Following Porter’s five‐force approach, we methodologically identify the economic market forces that shape the development of hydrogen markets, and discuss key obstacles in the supply chain. Using evidence of available hydrogen technologies and costs, the distribution network is identified as a major fixed‐investment barrier to market entry, but it is argued that much of it could be overcome if natural gas infrastructure and technology is shared with the hydrogen sector. Natural gas, in turn, is projected to function as a transition fuel under current carbon emissions targets. This study finds that policy costs needed to promote hydrogen to achieve environmental goals can be substantially reduced if government and private investment decisions strategically focus on synergies with natural gas. The possible formulation of such policies is discussed using Australia’s hydrogen industry as a case study.
Abstract
Aims
We aimed to determine whether treatment with sildenafil improves outcomes of patients with persistent pulmonary hypertension (PH) after correction of valvular heart disease (VHD).
...Methods and results
The sildenafil for improving outcomes after valvular correction (SIOVAC) study was a multricentric, randomized, parallel, and placebo-controlled trial that enrolled stable adults with mean pulmonary artery pressure ≥ 30 mmHg who had undergone a successful valve replacement or repair procedure at least 1 year before inclusion. We assigned 200 patients to receive sildenafil (40 mg three times daily, n = 104) or placebo (n = 96) for 6 months. The primary endpoint was the composite clinical score combining death, hospital admission for heart failure (HF), change in functional class, and patient global self-assessment. Only 27 patients receiving sildenafil improved their composite clinical score, as compared with 44 patients receiving placebo; in contrast 33 patients in the sildenafil group worsened their composite score, as compared with 14 in the placebo group odds ratio 0.39; 95% confidence interval (CI) 0.22–0.67; P < 0.001. The Kaplan–Meier estimates for survival without admission due to HF were 0.76 and 0.86 in the sildenafil and placebo groups, respectively (hazard ratio 2.0, 95% CI = 1.0–4.0; log-rank P = 0.044). Changes in 6-min walk test distance, natriuretic peptides, and Doppler-derived systolic pulmonary pressure were similar in both groups.
Conclusion
Treatment with sildenafil in patients with persistent PH after successfully corrected VHD is associated to worse clinical outcomes than placebo. Off-label usage of sildenafil for treating this source of left heart disease PH should be avoided.
The trial is registered with ClinicalTrials.gov, number NCT00862043.
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