A new integral equation formulation for American put options

In this paper, a completely new integral equation for the price of an American put option as well as its optimal exercise price is successfully derived. Compared to existing integral equations for pricing American options, the new integral formulation has two distinguishable advantages: (i) it is in a form of one-dimensional integral, and (ii) it is in a form that is free from any discontinuity and singularities associated with the optimal exercise boundary at the expiry time. These rather unique features have led to a significant enhancement of the computational accuracy and efficiency as shown in the examples

Optimum Spraying Time and Management Guidelines for Soybean Aphid Control

In Liaoning Province, the population of soybean aphid, Aphis glycines Matsumura, increases the most rapidly in late June, which is the critical period for aphid control. The current guideline for spraying is 10,000 aphids per100 plants. This guideline may be relaxed to 23,800 - 40,700 for cultivar Tiefeng #18 and to 26,500 – 33,000 for cultivar Liaodou #3 in the plains region found in the middle and lower reaches of Liaohe River. It is difficult to use aphid numbers as a management guideline in agricultural practice. According to our studies, the ratio of infested plants with rolled leaves is closely correlated to the aphid number per 100 plants. The linear regression equation is ? = 4.283 + 1.8419x (r = 0.90), where ? is the rolled leaf ratio and x is the aphid numbers per 100 plants. Therefore, instead of aphid numbers per 100 plants, we propose to use the ratio of plants with rolled leaves as the management guideline for large-scale field control of soybean aphids, which is 10% for Tiefeng #18 and 8% for Liaodou #3.Originating text in Chinese.Citation: He, Fugang, Yan, Fanyyue, Xin, Wanmin, Lii, Xiaoping, Wang, Yanqin, Zhang, Guangxue. (1991). Optimum Spraying Time and Management Guidelines for Soybean Aphid Control. Acta Phytophylacica Sinica, 18(2), 155-159

Effects of fence enclosure on vegetation community characteristics and productivity of a degraded temperate meadow steppe in Northern China

Species composition and biomass are two important indicators in assessing the effects of restoration measures of degraded grasslands. In this paper, we present a field study on the temporal changes in plant community characteristics, species diversity and biomass production in a degraded temperate meadow steppe in response to an enclosure measure in Hulunbuir in Northern China. Our results showed that the plant community responded positively to the fence enclosure in terms of vegetation coverage, height, above- and belowground biomass. A year-to-year increase in aboveground biomass was observed, and this increase plateaued at the ninth year of the enclosure. Our results also showed that the existing dominant and foundation species gained predominance against other species. The sum of the biomass of these two species was more than doubled after the ninth year of the enclosure. However, belowground biomass only briefly increased until the fifth year of the enclosure and then decreased until the end of the experimental period. Plant diversity, evenness, and richness indices showed similar trends to that of belowground biomass. Overall, we found that the degraded temperate meadow steppe responded significantly positively to the enclosure treatment, but an optimal condition was only reached after approximately 5-7 years of continuous protection, providing a solid use case for grassland conservation and management at regional scales

Fluorescent squaramides as anion receptors and transmembrane anion transporters

A series of squaramide-based anion transporters functionalised with the 1,8-naphthalimide fluorophore has been developed for improved ionophoric activity and fluorescent imaging in cells.112Ysciescopu

Early malperfusion, ischemia reperfusion injury, and respiratory failure in acute complicated type B aortic dissection after thoracic endovascular repair

BACKGROUND: The aim of this study was to determine the early mortality and major complications of acute complicated type B aortic dissection (ACBD) after thoracic endovascular aortic repair (TEVAR). METHODS: Twenty-six consecutive patients with ACBD who underwent TEVAR were included. Clinical indications before TEVAR and in-hospital mortality and major complications after TEVAR were analyzed and compared with similar reports. RESULTS: TEVAR was technically successful in all cases. In-hospital mortality occurred in four patients (15%), and major complications occurred in an additional four patients (15%). Three of the four (75%) of the deaths were associated with malperfusion and ischemia reperfusion injury (IRI), and 3/4 (75%) of the major complications were caused by respiratory failure (RF). CONCLUSIONS: In-hospital mortality associated strongly with severe end-organ malperfusion and IRI, while major complications associated with RF, during TEVAR. Our results indicate that malperfusion, IRI and respiratory failure during TEVAR should be carefully monitored and aggressively treated