We introduce a model of a market where risk-averse consumers pay a fee to transfer their future losses to one or more firms.The future loss of each consumer is stochastic with a unique,known mean and variance.The law ...We introduce a model of a market where risk-averse consumers pay a fee to transfer their future losses to one or more firms.The future loss of each consumer is stochastic with a unique,known mean and variance.The law of large numbers allows the firms to know with certainty the expected aggregate loss of the consumers to whom they sell.The model could describe the behavior of agents in the market for property insurance where an insurance company sells a single type of policy to a specific group of consumers based upon the expected losses of those consumers and their willingness to pay for coverage.The model demonstrates how a single firm can choose the optimal segment of the market to which they sell a policy and how that choice might change when the distribution of consumers and their risk aversion changes.The model also demonstrates how two firms might engage in a cooperative strategy and share the market.The model shows how a firm entering the market will find it more advantageous to target a segment of the market with consumers that have a lower expected loss.展开更多
Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialle...Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings （Tilia cordata Mill.） were planted with a 1 x 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings （2475 cherries and 825 limes） were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots （10 × 10 m） were randomly established in group and row planting stand, respectively. The survival rate, stability （height to diameter ratio）, diameter, and height growth were significantly higher in group planting. In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an important reason for the difference in performance between group and row planting. This study will encourage forest practitioners to establish more cherry group planting trials on multiple sites to test the effectiveness of this alternative technique as a tool of regeneration and restoration silviculture.展开更多
文摘We introduce a model of a market where risk-averse consumers pay a fee to transfer their future losses to one or more firms.The future loss of each consumer is stochastic with a unique,known mean and variance.The law of large numbers allows the firms to know with certainty the expected aggregate loss of the consumers to whom they sell.The model could describe the behavior of agents in the market for property insurance where an insurance company sells a single type of policy to a specific group of consumers based upon the expected losses of those consumers and their willingness to pay for coverage.The model demonstrates how a single firm can choose the optimal segment of the market to which they sell a policy and how that choice might change when the distribution of consumers and their risk aversion changes.The model also demonstrates how two firms might engage in a cooperative strategy and share the market.The model shows how a firm entering the market will find it more advantageous to target a segment of the market with consumers that have a lower expected loss.
基金financially supported by a research grant from the German Agency for Renewable Resources(Fachagentur Nachwachsende Rohstoffe e.V or FNR,Grant Number:22008813)
文摘Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings （Tilia cordata Mill.） were planted with a 1 x 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings （2475 cherries and 825 limes） were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots （10 × 10 m） were randomly established in group and row planting stand, respectively. The survival rate, stability （height to diameter ratio）, diameter, and height growth were significantly higher in group planting. In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an important reason for the difference in performance between group and row planting. This study will encourage forest practitioners to establish more cherry group planting trials on multiple sites to test the effectiveness of this alternative technique as a tool of regeneration and restoration silviculture.
