8,392 research outputs found

    How Values Create Value: Social Capital in Microfinance - The Case of the Philippines

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    Values are to a society what character is to a person: it reveals his true inner self, yet is difficult to describe in exact terms. Moreover, a person's character may show in his actions in various, sometimes contradictory ways so that it may be difficult to induce a person's character from his deeds. Asian values, elusive as they are, have been regarded as a cause of the economic rise of a number of Asian countries. Yet some decades earlier, Confucian values were quoted as a cause of underdevelopment of some Asian countries. Has the recent financial crisis also been due to them, in some way, or do we have to wait for economic recovery in order to attribute that to Confucian values? Max Weber, who first studied the impact of values on economic development, was more careful when he presented the results of his research. The Spirit of Capitalism is congruent with the rise of the Protestant Ethic, he said; but he claimed no causal relationship. --

    Innovations in energy and climate policy: lessons from Vermont

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    We ask in this article: how can planners and policymakers replicate Vermont’s energy and climate policies? We begin by explaining the research methods utilized for this article—mainly research interviews with a pool of experts, coupled with a targeted literature review. We then analyze the success of Vermont energy policy across four areas: energy efficiency, renewable energy, the smart grid, and energy governance. The following sections first explain how Vermont accomplished these successes, next identify a number of remaining barriers and elements of Vermont’s approach that may not be replicable, and finally present the article’s conclusions

    Carbon pathways in the global gas market: An attributional lifecycle assessment of the climate impacts of liquefied natural gas exports from the United States to Asia

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    While the United States is poised to become a major exporter of liquefied natural gas (LNG), relatively little attention has been paid to greenhouse gas emission impacts from exporting US natural gas to Asia, a key likely destination. Using bounding scenarios of attributional lifecycle analysis, this study finds that the climate impacts of US exports to China, Japan, India, or South Korea could vary significantly, with annual global lifecycle emissions ranging from -88,000 metric tons CO2e to +170,000 metric tons CO2e per Bcf of exports. Exact emissions will depend on factors such as (a) the final end-use of the LNG, (b) domestic market impacts from increased natural gas prices in the U.S., (c) induced additional energy consumption in importing countries, and (d) methane leakage rates. Country specific GHG outcomes can differ from global GHG outcomes, with major implications for extraction and consumption based emissions accounting. The study’s results indicate the need for more robust consideration of the climate impacts of all energy exports in terms of country specific energy analyses, global climate regulations, and market uncertainty. Thus, how gas is governed becomes of critical importance, for it will determine whether LNG is a net sink or source of additional emissions

    Benchmarking natural gas and coal-fired electricity generation in the United States

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    This study answers a critical question facing the energy sector in the United States: how does natural gas compare to coal as a climate change mitigation technique? Although natural gas burns cleaner than coal, methane leakage potentially undermines the climate benefits of fuel switching. This study investigates the impact of methane leakage using a novel plant-level lifecycle emissions inventory of greenhouse gas emissions associated with coal mining, transportation, and combustion at 337 existing coal power plants in the United States. Individual plant emissions rates ranged from 901 to more than 2,200 kgCO2e/MWh (100-yr GWP); generation-weighted average was 1,046 kgCO2e/MWh. Our study finds that the “breakeven” leakage rates for natural gas to have short and long term climate benefits over coal range from 4.4-20.9%, depending on the timeframe, plant efficiency, and upstream coal emissions. Emissions benefits can be maximized by replacing highest emitting coal plants with new natural gas plants. Finally, we find fugitive methane emissions can limit carbon reductions from natural gas carbon capture; above 2% leakage, methane leakage reduces CCS benefits by up to half for 20-yr GWP

    Constraints for the Progenitor Masses of Historic Core-Collapse Supernovae

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    We age-date the stellar populations associated with 12 historic nearby core-collapse supernovae (CCSNe) and 2 supernova impostors, and from these ages, we infer their initial masses and associated uncertainties. To do this, we have obtained new HST imaging covering these CCSNe. Using these images, we measure resolved stellar photometry for the stars surrounding the locations of the SNe. We then fit the color-magnitude distributions of this photometry with stellar evolution models to determine the ages of any young existing populations present. From these age distributions, we infer the most likely progenitor mass for all of the SNe in our sample. We find ages between 4 and 50 Myr, corresponding to masses from 7.5 to 59 solar masses. There were no SNe that lacked a young population within 50~pc. Our sample contains 4 type Ib/c SNe; their masses have a wide range of values, suggesting that the progenitors of stripped-envelope SNe are binary systems. Both impostors have masses constrained to be \lesssim7.5 solar masses. In cases with precursor imaging measurements, we find that age-dating and precursor imaging give consistent progenitor masses. This consistency implies that, although the uncertainties for each technique are significantly different, the results of both are reliable to the measured uncertainties. We combine these new measurements with those from our previous work and find that the distribution of 25 core-collapse SNe progenitor masses is consistent with a standard Salpeter power-law mass function, no upper mass cutoff, and an assumed minimum mass for core-collapse of 7.5~M_{\odot}.Comment: 12 pages, 4 tables, 4 figures, accepted for publication in Ap

    Constraints for the Progenitor Masses of 17 Historic Core-Collapse Supernovae

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    Using resolved stellar photometry measured from archival HST imaging, we generate color-magnitude diagrams of the stars within 50 pc of the locations of historic core-collapse supernovae that took place in galaxies within 8 Mpc. We fit these color-magnitude distributions with stellar evolution models to determine the best-fit age distribution of the young population. We then translate these age distributions into probability distributions for the progenitor mass of each SNe. The measurements are anchored by the main-sequence stars surrounding the event, making them less sensitive to assumptions about binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate that, in cases where the literature contains masses that have been measured from direct imaging, our measurements are consistent with (but less precise than) these measurements. Using this technique, we constrain the progenitor masses of 17 historic SNe, 11 of which have no previous estimates from direct imaging. Our measurements still allow the possibility that all SNe progenitor masses are <20 M_sun. However, the large uncertainties for the highest-mass progenitors also allow the possibility of no upper-mass cutoff.Comment: 13 pages, 9 figures, 3 tables, accepted for publication in Ap

    Theoretical predictions for how temperature affects the dynamics of interacting herbivores and plants

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    Concern about climate change has spurred experimental tests of how warming affects species' abundance and performance. As this body of research grows, interpretation and extrapolation to other species and systems have been limited by a lack of theory. To address the need for theory for how warming affects species interactions, we used consumer-prey models and the metabolic theory of ecology to develop quantitative predictions for how systematic differences between the temperature dependence of heterotrophic and autotrophic population growth lead to temperature-dependent herbivory. We found that herbivore and plant abundances change with temperature in proportion to the ratio of autotrophic to heterotrophic metabolic temperature dependences. This result is consistent across five different formulations of consumer-prey models and over varying resource supply rates. Two models predict that temperaturedependent herbivory causes primary producer abundance to be independent of temperature. This finding contradicts simpler extensions of metabolic theory to abundance that ignore trophic interactions, and is consistent with patterns in terrestrial ecosystems. When applied to experimental data, the model explained 77% and 66% of the variation in phytoplankton and zooplankton abundances, respectively. We suggest that metabolic theory provides a foundation for understanding the effects of temperature change on multitrophic ecological communities

    Comparative genetics of Enterococcus faecalis intestinal tissue isolates before and after surgery in a rat model of colon anastomosis.

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    We have recently demonstrated that collagenolytic Enterococcus faecalis plays a key and causative role in the pathogenesis of anastomotic leak, an uncommon but potentially lethal complication characterized by disruption of the intestinal wound following segmental removal of the colon (resection) and its reconnection (anastomosis). Here we hypothesized that comparative genetic analysis of E. faecalis isolates present at the anastomotic wound site before and after surgery would shed insight into the mechanisms by which collagenolytic strains are selected for and predominate at sites of anastomotic disruption. Whole genome optical mapping of four pairs of isolates from rat colonic tissue obtained following surgical resection (herein named "pre-op" isolates) and then 6 days later from the anastomotic site (herein named "post-op" isolates) demonstrated that the isolates with higher collagenolytic activity formed a distinct cluster. In order to perform analysis at a deeper level, a single pair of E. faecalis isolates (16A pre-op and 16A post-op) was selected for whole genome sequencing and assembled using a hybrid assembly algorithm. Comparative genomics demonstrated absence of multiple gene clusters, notably a pathogenicity island in the post-op isolate. No differences were found in the fsr-gelE-sprE genes (EF1817-1822) responsible for regulation and production of collagenolytic activity. Analysis of unique genes among the 16A pre-op and post-op isolates revealed the predominance of transporter systems-related genes in the pre-op isolate and phage-related and hydrolytic enzyme-encoding genes in the post-op isolate. Despite genetic differences observed between pre-op and post-op isolates, the precise genetic determinants responsible for their differential expression of collagenolytic activity remains unknown
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