Recent extreme fire seasons in California have prompted utilities such as Pacific Gas and Electric to pre-emptively de-energize portions of the electrical grid during periods of extreme fire weather ...to reduce the risk of powerline-related fire ignitions. The policy was deployed in 2019, resulting in 12 million person-days of power outages and widespread societal disruption. Retrospective weather and vegetation moisture data highlight hotspots of historical risk across northern California. We estimate an average of 1.6 million person-days of de-energization per year, based on recent historical climate conditions and assuming publicly stated utility de-energization thresholds. We further estimate an additional 70% increase in the population affected by de-energization when vegetation remains abnormally dry later into autumn-suggesting that climate change will likely increase population vulnerable to de-energization. Adaptation efforts to curtail fire risk can be beneficial, but efforts to prepare affected populations, modernize the grid, and refine decision-making surrounding such policies have high potential to reduce the magnitude of negative externalities experienced during the 2019 de-energization events.
Travel-time based hydraulic tomography is a promising method to characterize heterogeneity of porous-fractured aquifers. However, there is inevitable noise in field-scale experimental data and many ...hydraulic signal travel times, which are derived from the pumping test’s first groundwater level derivative drawdown curves and are strongly influenced by noise. The required data processing is thus quite time consuming and often not accurate enough. Therefore, an effective and accurate de-noising method is required for travel time inversion data processing. In this study, a series of hydraulic tomography experiments were conducted at a porous-fractured aquifer test site in Goettingen, Germany. A numerical model was built according to the site’s field conditions and tested based on diagnostic curve analyses of the field experimental data. Gaussian white noise was then added to the model’s calculated pumping test drawdown data to simulate the real noise in the field. Afterward, different de-noising methods were applied to remove it. This study has proven the superiority of the wavelet de-noising approach compared with several other filters. A wavelet de-noising method with calibrated mother wavelet type, de-noising level, and wavelet level was then determined to obtain the most accurate travel time values. Finally, using this most suitable de-noising method, the experimental hydraulic tomography travel time values were calculated from the de-noised data. The travel time inversion based on this de-noised data has shown results consistent with previous work at the test site.
Introduction:
Patients in cardiac arrest treated with resuscitative thoracotomy and open cardiac massage (OCM) have high rates of mortality with poor neurological outcomes. The aim of this study is ...to quantitate cerebral perfusion during OCM using computed tomography perfusion (CTP) imaging in a swine model of normo- and hypovolemia.
Methods:
Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Cerebral blood flow (CBF; ml/100 g of brain) and time to peak (TTP; s) were measured. Animals were then euthanized by exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group) and subjected to a clamshell thoracotomy, aortic cross clamping, OCM, and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCoPP; mmHg) were collected and % CoPP > 15 mmHg (% CoPP; s) calculated post hoc.
Results:
Normovolemic animals (
n
= 5) achieved superior pCoPP compared to the hypovolemic animals (
n
= 5) pCoPP (39.3 vs. 12.3,
p
< 0.001) and % CoPP (14.5 ± 1.9 vs. 30.9 ± 6.5,
p
< 0.001). CTP acquisition was successful and TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs. 10.8 vs. 14.8,
p
= 0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs. 4.9 ± 6.0,
p
= 0.73) which was significantly lower than baseline values (51.9 ± 12.1,
p
< 0.001).
Conclusion:
OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.
This paper critically analyzes the disjuncture between rural electrification initiatives, utilization and socioeconomic development resulting from development of small hydropower (SHP) operations in ...rural Yunnan Province. Across China, a contemporary rapid and sustained proliferation of SHP is driven by government-led programs endorsing the technology as a means to provide energy for isolated communities in areas where grid connectivity is deficient or absent. Through SHP development, rural electrification programs (REP’s) are purported to raise quality-of-life indicators in some of the country’s poorest and most marginalized areas. Currently, there is a significant dearth of research critically analyzing the success or failures of SHP based REP’s in China to improve livelihoods for ethnic minority communities in rural and remote areas. This paper adds to a shallow body of China based research by analyzing outcomes of SHP development through a comparative study undertaken in two rural village communities in the upper Nu River Valley. The study analyzed a range of quantitative economic data before undertaking a suite of qualitative methods such as participant observation, household surveys, semi-structured interviews and focus groups, staggered over multiple field visits. Findings indicate substantial scope exists for SHP based REP’s to achieve stated objectives for improving socioeconomic indicators in rural and remote communities. Due to a range of challenges, however, projects often underachieve or further marginalize residents, commonly mired by failures in strategic planning, lack of implementation frameworks and genuine engagement with community members. A number of recommendations are offered as pathways to improve SHP based REP’s as a means to provide conditions for more equitable modes of socioeconomic development across rural and marginal China.
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Understanding the complex nature of "China" is fundamental when considering its role in the Mekong region. Here, Ptak investigates the shifting regional geopolitics of Mekong river dams.
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Travel time based hydraulic tomography is a technique for reconstructing the spatial distribution of aquifer hydraulic properties (e.g., hydraulic diffusivity). Simultaneous Iterative Reconstruction ...Technique (SIRT) is a widely used algorithm for travel time related inversions. Due to the drawbacks of SIRT implementation in practice, a modified SIRT with Cimmino iteration (SIRT-Cimmino) is proposed in this study. The incremental correction is adjusted, and an iteration-dependent relaxation parameter is introduced. These two modifications enable an appropriate speed of convergence, and the stability of the inversion process. Furthermore, a new result selection rule is suggested to determine the optimal iteration step and its corresponding result. SIRT-Cimmino and SIRT are implemented and verified by using two numerical aquifer models with different predefined (“true”) diffusivity distributions, where high diffusivity zones are embedded in a homogenous low diffusivity field. Visual comparison of the reconstructions shows that the reconstruction based on SIRT-Cimmino demonstrates the aquifer’s hydraulic features better than the conventional SIRT algorithm. Root mean square errors and correlation coefficients are also used to quantitatively evaluate the performance of the inversion. The reconstructions based on SIRT-Cimmino are found to preserve the connectivity of the high diffusivity zones and to provide a higher structural similarity to the “true” distribution.
The spatial distribution of aquifer hydraulic parameters is an important and basic factor to study groundwater seepage, groundwater pollutant transport processes and many other groundwater related ...problems.However, due to the limitation of conventional exploration technology, the spatial heterogeneity of aquifer hydraulic parameters cannot be described accurately and intuitively.Especially for fractured aquifers, the heterogeneity of hydraulic parameters is much stronger.In order to solve this problem, this study attempts to characterize the hydraulic properties of a fractured aquifer by using travel time based hydraulic tomography.Firstly, the head data at 8 different depths (receivers) in the observation well are recorded through 64 multi-level short-term pumping tests at 8 pumping intervals (sources) in the pumping well with help of double packers performed in Goettingen Germany.All these 64 head response data are used to calculate the hydraulic parameters (K and Ss) with Jacobian analytical solution.Subse
Coastal zones connect terrestrial and marine ecosystems forming a unique environment that is under increasing anthropogenic pressure. Rising sea levels, sinking coasts, and changing precipitation ...patterns modify hydrodynamic gradients and may enhance sea-land exchange processes in both tidal and non-tidal systems. Furthermore, the removal of flood protection structures as restoration measure contributes locally to the changing coastlines. A detailed understanding of the ecosystem functioning of coastal zones and the interactions between connected terrestrial and marine ecosystems is still lacking. Here, we propose an interdisciplinary approach to the investigation of interactions between land and sea at shallow coasts, and discuss the advantages and the first results provided by this approach as applied by the research training group Baltic TRANSCOAST. A low-lying fen peat site including the offshore shallow sea area on the southern Baltic Sea coast has been chosen as a model system to quantify hydrophysical, biogeochemical, sedimentological, and biological processes across the land-sea interface. Recently introduced rewetting measures might have enhanced submarine groundwater discharge as indicated by distinct patterns of salinity gradients in the near shore sediments, making the coastal waters in front of the study site a mixing zone of fresh- and brackish water. High nutrient loadings, dissolved inorganic carbon, and dissolved organic matter originating from the degraded peat may affect micro- and macro-phytobenthos, with the impact propagating to higher trophic levels. The terrestrial part of the study site is subject to periodic brackish water intrusion caused by occasional flooding, which has altered the hydraulic and biogeochemical properties of the prevailing peat soils. The stable salinity distribution in the main part of the peatland reveals the legacy of flooding events. Generally, elevated sulfate concentrations are assumed to influence greenhouse gas emissions, mainly by inhibiting methane production, yet our investigations indicate complex interactions between the different biogeochemical element cycles (e.g. carbon and sulfur) caused by connected hydrological pathways. In conclusion, sea-land interactions are far reaching, occurring on either side of the interface, and can only be understood when both long-term and event-based patterns and different spatial scales are taken into account in interdisciplinary research that involves marine and terrestrial expertise.
Polycrystalline silicon is an essential input for solar photovoltaic technologies, commonly found in quartz and sand. India's headlong lunge into solar power will require an immense amount of ...domestically sourced polycrystalline silicon from Uttar Pradesh. Drawing on mixed-methods fieldwork, this study asks the following research question: Which factors produce the precarity of silica miners? This study found that Dalit miners are being dispossessed of their livelihoods through the mechanization of silica mining. Miners were also victims of workplace hazards, accidents, and ecological degradation. The dead labor of silica and the living laborers facing premature death from mining injustices will haunt India's low-carbon futures. Silica territorialities of India are a palimpsest, where precarity written in the sand is transposed by prefigurative politics that can author an emancipatory solar manifesto. Against the grains, exhumed miners of silica extraction for solar power will assume their place in the sun.
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