Both China’s national subsidy policies for plug-in electric vehicles (PEVs) purchasers and passenger cars corporate average fuel consumption and new vehicle credit regulation (dual-credit policy) favor long-range 300+ km battery electric vehicles (BEVs) and 80+ km plug-in hybrid electric vehicles (PHEVs). However, these electric vehicles tend to have lower energy efficiency and higher purchase and operation costs. Vehicle with larger batteries can also be less equitable because the subsidies are often provided to more expensive vehicles and wealthier owners. This study takes advantage of a novel dataset of daily driving data from 39,854 conventional gasoline vehicles in Beijing and 4999 PHEVs in Shanghai to determine the optimal range of BEVs and PHEVs within their respective cities. We simulate a model to explore ranges with which PEVs emit less GHGs than that of a baseline hybrid and conventional gasoline vehicle while ensuring that all daily travel demands are met. Our findings indicate that in both cities, the optimal ranges to balance cost and travel demand for BEVs are 350 km or less and for PHEVs are 60 km or less in Beijing and 80 km or less in Shanghai. We also find that to minimize carbon dioxide (CO2) emissions, the ranges are even lower 10 km in Beijing and 30 km in Shanghai. Our study suggests that instead of encouraging long-range PEVs, governments should subsidize PEV models with shorter ranges. Parallel efforts should also be made to both increase renewable energy over fossil fuels and expand charging facilities. Although individual mobility demand varies, the government could reduce occasional long-distance driving by subsidizing alternative transportation choices. Providing week-long driving trials to consumers before their purchases may help decrease the demand of very long range PEVs by alleviating the range anxiety through a learning process.
Summary The evolution of cooperation requires either (a) nonrandom interactions, such that cooperators preferentially interact with other cooperators, or (b) conditional behaviors, such that individuals act cooperatively primarily towards other cooperators. Although these conditions can be met without assuming sophisticated animal cognition, they are more likely to be met if animals can remember individuals with whom they have interacted, associate past interactions with these individuals, and base future behavior on this information. Here we show that guppies (Poecilia reticulata), in the context of predator inspection behavior, can identify and remember (for at least 4 h) the more cooperative among two conspecifics and subsequently choose to be near these individuals in future encounters.
Offprint requests to: L.A. Dugatkin 相似文献
McMurdo Station is the largest research station in Antarctica, with a population that ranges each year from 250 to 1200 people. Because of its size and 40-year history of use, a number of locations around the station have become contaminated with wastes. Soils and sediments in these areas have been shown to contain elevated levels of petroleum-related products, PCBs, other organics, and metals. While some remedial investigations have been conducted, background levels of metals in soils have not been determined. This paper reports on background levels of metals in a natural basalt-derived soil (gray soil) and scoria (soft porous rock used as fill, red soil) near McMurdo Station using two fundamentally different analytical procedures, concentrated acid extraction/analysis and total metals. These data facilitate determining the extent and levels of metal contamination near McMurdo Station and provide reference levels of metals for comparison with existing and future remediation data. There were statistically significant differences between metals concentrations in both gray and red soils, and no correlations between the level of extracted versus total metal. Generally, only a small fraction of a metal was extractable. 相似文献
Selective termination by intracardiac potassium chloride injection was performed in twins discordant for hydrocephaly at 20 weeks' gestation. Because of the potential for vascular anastomoses to exist between the twins, fetal angiography was performed prior to the selective termination procedure. Determination of vascular connections between the fetuses was hindered by fetal bradycardia following intracardiac administration of contrast material. Selective termination was performed without difficulty using intracardiac potassium chloride (KCl) to produce asystole in the twin with hydrocephaly. The unaffected fetus appeared active and had a normal heart rate during and immediately after the procedure. However, both twins were found to have died the following day. Pathologic examination documented several vascular anastomoses between the monochorionic, diamniotic fetuses. A likely cause of death was exsanguination of the normal twin into the abnormal one. This case illustrates the difficulties encountered in selective termination of monozygotic twins and, to our knowledge, represents the first reported use of intrauterine fetal angiography. 相似文献
Fetal nucleated erythrocytes (NRBC) in maternal blood are a non-invasive source of fetal DNA for prenatal genetic screening. We compared the effectiveness of three monoclonal antibodies for the separation of fetal cells from maternal blood by flow sorting. Mononuclear blood cells from 49 healthy pregnant women were incubated with antibody to CD 71, CD 36, and/or glycophorin A (GPA), employed singly or in combination with each other. These monoclonal antibodies recognize surface antigens on haematopoietic precursor cells. Successful isolation of fetal cells was defined as detection of Y chromosomal sequences in maternal blood from women carrying male fetuses, with absence of Y sequences when female fetuses were carried. Thus, gender prediction accuracy was used as a measure of fetal cell separation. Using anti-CD 71 to isolate fetal cells, gender prediction was 57 per cent correct; with anti-CD 36, it was 88 per cent correct. Anti-GPA, an erythrocyte-specific antigen, used alone or in combination with anti-CD 71 or 36, improved gender prediction to 100 per cent. We conclude that antibody to GPA improves the retrieval of fetal NRBC from maternal blood, permitting genetic analysis by the polymerase chain reaction. 相似文献
The problem of resolving the homology of the digits of the avian hand has been framed as a conflict between paleontological and embryological evidence, the former thought to support a hand composed of digits I, II, III, because of similarity of the phalangeal formulae of the earliest known bird Archaeopteryx to that of Mesozoic pentadactyl archosaurs, while embryological evidence has traditionally favored a II, III, IV avian hand. We have identified the critical developmental period for the major features of the avian skeleton in a primitive bird, the ostrich. Analysis of digit anlagen in the avian hand has revealed those for digits/metacarpals I and V, thus confirming previous embryological studies that indirectly suggested that the avian hand comprises digits II, III, IV, and was primitively pentadactyl. 相似文献
In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague. 相似文献