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考虑下列资产组合，按执行价90美元卖出一份看跌期权。执行价95美元买入一份看跌期权。标的股票与到期日都相同。 a．画出期权到期日时该资产组合的价值。 b．在同一张图上，画出该资产组合的利润。哪种期权的成本较高？
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This week, the flagship of that effort, the Global Seed Vault near here, received its first seeds, millions of them. Bored into the middle of a frozen Arctic mountain topped with snow, the vault？ s goal is to store and protect samples of every type of seed from every seed collection in the world.
As of Thursday, thousands of neatly stacked and labeled gray boxes of seeds — peas from Nigeria, corn from Mexico — reside in this glazed cavelike structure, forming a sort of backup hard drive, in case natural disasters or human errors erase the seeds from the outside world.
Descending almost 500 feet under the permafrost, the entrance tunnel to the seed vault is designed to withstand bomb blasts and earthquakes. An automated digital monitoring system controls temperature and provides security akin to a missile silo or Fort Knox. No one person has all the codes for entrance.
The Global Vault is part of a broader effort to gather and systematize information about plants and their genes, which climate change experts say may indeed prove more valuable than gold. In Leuven, Belgium, scientists are scouring the world for banana samples and preserving their shoots in liquid nitrogen before they become extinct. A similar effort is under way in France on coffee plants. A number of plants, most from the tropics, do not produce seeds that can be stored.
For years, a hodgepodge network of seed banks has been amassing seed and shoot collections in a haphazard manner. Labs in Mexico banked corn species. Those in Nigeria banked cassava. Now these scattershot efforts are being urgently consolidated and systematized, in part because of better technology to preserve plant genes and in part because of the rising alarm about climate change and its impact on world food production.
“We started thinking about this post-9/11 and on the heels of Hurricane Katrina,” said Cary Fowler, president of the Global Crop Diversity Trust, a nonprofit group that runs the vault. “Everyone was saying, why didn？ t anyone prepare for a hurricane before？ We knew it was going to happen.“Well, we are losing biodiversity every day — it？ s a kind of drip, drip, drip. It？ s also inevitable. We need to do something about it.”
This week the urgency of the problem was underscored as wheat prices rose to record highs and wheat stores dropped to the lowest level in 35 years. A series of droughts and new diseases cut wheat production in many parts of the world. “The erosion of plants？ genetic resources is really going fast,” said Dr. Rony Swennen, head of the division of crop biotechnology at the Catholic University of Leuven in Belgium, who has preserved half of the world？ s 1,200 banana types. “We？ re at a critical moment and if we don？ t act fast, we？ re going to lose a lot of plants that we may need.”
The United Nations International Treaty on Plant Genetic Resources, ratified in 2004, created a formal global network for banking and sharing seeds, as well as for studying their genetic traits. Last year, its database received thousands of new seeds.
A system of plant banks could be crucial in responding to climate crises since it could identify genetic material and plant strains better able to cope with a changed environment.
Here at the Global Vault, hundreds of gray boxes containing seeds from places ranging from Syria to Mexico were moved this week into a freezing vault to be placed in suspended animation. They harbor a vast range of qualities, like the ability to withstand drier, warmer climate.
When night falls in remote parts of Africa and the Indian subcontinent, hundreds of millions of people without access to electricity turn to candles or flammable and polluting kerosene lamps for illumination.
Slowly through small loans for solar powered devices, microfinance is bringing light to these rural regions where a lack of electricity has stymied economic development, literacy rates and health. A woman sews clothes on a sewing machine driven by solar energy in Ahmedabad/ Photo credit: Amit Dave/ Reuters
“Earlier, they could not do much once the sun set. Now, the sun is used differently. They have increased their productivity, improved their health and socio-economic status,” said Pinal Shah from SEWA Bank, a micro -lending institution.
Vegetable seller Ramiben Waghri took out a loan to buy a solar lantern which she uses to light up her stall at night. The lantern costs between $66-$112, about a week？ s income for Waghri.
“The vegetables look better by this light, and it？ s cheaper than kerosene and doesn？ t smell,” said Waghri, who estimates she makes about 300 rupees ($6) more each evening with her lantern.
“If we can use the sun to save some money, why not？”
In India, solar power projects, often funded by micro credit institutions, are helping the country reduce carbon emissions and achieve its goal to double the contribution of renewable energy to 6%, or 25,000 megawatts, within the next four years.
Off-grid applications such as solar cookers and lanterns, which can provide several hours of light at night after being charged by the sun during the day, will help cut dependence on fossil fuels and reduce the fourth biggest emitter？ s carbon footprint, said Pradeep Dadhich, a senior fellow at energy research institute TERI.
“They are reaching people who otherwise have limited or no access to electricity, and depend on kerosene, diesel or firewood for their energy needs,” he said.“The applications not only satisfy these needs, they also improve the quality of life and reduce the carbon footprint.”
SEWA or Self Employed Women？ s Association, is among a growing number of microfinance institutions in India focused on providing affordable renewable energy sources to poor people, who otherwise would have had to stand for hours to buy kerosene for lamps, or trudge miles to collect firewood for cooking.
SKS Microfinance, India？ s largest MFI, offers solar lamps to its 5 million customers, while Grameen Surya Bijlee (Rural Solar Electricity) Foundation helps fund lamps and home and street lighting systems for villagers in India, Nepal and Bangladesh.
果树繁殖的方法有有性繁殖和无性繁殖两种。通过种子繁殖的苗木称为（）
利用布莱克一斯科尔斯期权定价公式解决以下问题。假定：S0=70美元，X=75美元；T=365天，r=0．06年付，σ=0．45。在期权到期前没有股息发放。看涨期权的价值是_______。
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