63,664 research outputs found

    Efficacy of laser preionization with a semiconductor source and propene addition

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    It is established that propene is an effective additive instabilising uv preionised CO2 TEA laser discharges: its effect being particularly pronounced with semiconductor-edge preionised lasers where the preionisation levels are shown to be low

    Do lemurs know when they could be wrong? An investigation of information seeking in three species of lemur (<i>Lemur catta, Eulemur rubriventer, </i>and<i> Varecia variegata</i>)

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    Sixteen lemurs, including representatives from three species (Lemur catta, Eulemur rubriventer, Varecia variegata), were presented with a food seeking task where information about the rewards location, in one of two plastic tubes, was either known or not known. We evaluated whether lemurs would first look into the tube prior to making a choice. This information-seeking task aimed to assess whether subjects would display memory awareness, seeking additional information when they became aware they lacked knowledge of the rewards location. We predicted lemurs would be more likely to look into the tube when they had insufficient knowledge about the rewards position. Lemurs successfully gained the reward on most trials. However, they looked on the majority of trials regardless of whether they had all the necessary information to make a correct choice. The minimal cost to looking may have resulted in checking behaviour both to confirm what they already knew and to gain knowledge they did not have. When the cost of looking increased (elevating end of tube requiring additional energy expenditure to look inside - Experiment 2), lemurs still looked into tubes on both seen and unseen trials; however, the frequency of looking increased when opaque tubes were used (where they could not see the rewards location after baiting). This could suggest they checked more when they were less sure of their knowledge state

    Martian sample sites: Examples based on a global geologic perspective

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    Ten areas were selected that each include several rock units of varying lithology and age. These areas were chosen to optimize the geologic and chronologic data return from Mars. Geologic mapping and stratigraphic studies identify stratigraphic ages, rock types, and information on Martian geologic history that samples of a given site may yield. Volcanic rocks occur over much of the planet and in virtually all stratigraphic positions, and they are amenable to radioisotopic dating. Therefore, a reasonable and essential goal for a sample return mission is to return datable rocks from widely varying strata. Generally, about three or four major geologic units can be sampled at any of the given sites, most of which can probably be dated. The Mars Observer mission will aid greatly in interpreting lithology and defining contacts at the high resolution required to actually pinpoint good sample acquisition sites within these areas

    Long, paired A'A/Pahoehoe flows of Mauna Loa: Volcanological significance and insights they provide into volcano plumbing systems

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    The long lava flows of Mauna Loa, Hawaii have been cited as Earth's closed analogs to the large Martian flows. It is therefore important to understand the flow mechanics and characteristics of the Mauna Loa flows and to make use of these in an attempt to gain insights into Martian eruptive processes. Two fundamentally different kinds of long lava flows can be distinguished on Hawaiian volcanoes as in Martian flows. The two kinds may have identical initial viscosities, chemical compositions, flow lengths, and flow volumes, but their flow mechanisms and thermal energy budgets are radically different. One travels a distance set by the discharge rate as envisaged by Walker and Wadge, and the other travels a distance set mainly by the eruption duration and ground slope. In the Mauna Loa lavas, yield strength becomes an important flow morphology control only in the distal part of a'a lavas. The occurrence of paired flows on Mauna Loa yields insights into the internal plumbing systems of the volcano, and it is significant that all of the volume of the a'a flow must be stored in a magma chamber before eruption, while none of the volume of the pahoehoe needs to be so stored. Differentiation between the two kinds of flows on images of Martian volcanoes is possible and hence an improved understanding of these huge structures is acquired

    THE VALUE OF USDA OUTLOOK INFORMATION: AN INVESTIGATION USING EVENT STUDY ANALYSIS

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    The economic value of public situation and outlook information has long been a subject of debate. The purpose of this paper is to investigate the economic value of USDA WASDE reports in corn and soybean markets. The investigation is based on event study analysis, with the "events" consisting of the release of all monthly USDA WASDE reports for corn and soybeans from 1985 through 1998. The WASDE reports during the sample period are divided into two groups: one that represents "pure" outlook information and one that represents a "mix" of situation and outlook information. The statistical tests can be placed into two categories: mean price reaction and volatility reaction. Overall, the results suggest that USDA outlook information has a significant impact in corn and soybean markets. The most notable impact is found in options markets, where implied volatility consistently declines after the release of WASDE reports. For the group of monthly reports containing only outlook information, implied volatility for both corn and soybeans was lower on the report day than on the previous day about 60 percent of the time. The difference in mean implied volatility on the day of the report and on the previous day for both corn and soybeans was significantly different from zero. The average magnitude of the drop was between about two- and three-tenths of a percentage point (of annualized implied volatility), which would appear to be an economically non-trivial decrease. Hence, it can be concluded that USDA outlook information reduces the uncertainty of market participants' expected distribution of future prices. This reduction in market uncertainty is unambiguously welfare-enhancing.Crop Production/Industries, Marketing,

    Diurnal variation in harbour porpoise detection – potential implications for management

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    Our Sacred Mountains: A Case Study of Sagarmatha National Park and UNESCO's Categorization

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    This paper explores sacred mountains and their categorization as cultural landscapes with a focus on Sagarmatha National Park (SNP), one of the first mountain sites inscribed on the World Heritage List (WHL). Inscribed under natural heritage criteria (criterion vii), SNP is identified with superlative natural phenomena or areas of exceptional natural beauty and aesthetic importance. Given that SNP was inscribed to the WHL prior to the emergence of UNESCO’s cultural landscape category, this paper argues that the classificatory systems and categorization adopted by governments and organizations - such as UNESCO - can threaten the holistic, tangible/intangible, cultural/natural essence of sites. The paper unpacks through a combined semiotic and textual analysis of images, text, and impressions of visitors and residents, the cultural features of SNP, and advocates for its re-nomination as a cultural landscape. Re-nomination is critical due to the implications that the narrow interpretation of SNP as a natural site have for inhabitants, visitors and long-term sustainability. UNESCO’s re-nomination process and categories are questioned as an over-lap between mixed sites and cultural landscapes becomes evident. The paper ultimately ex-amines whether categorization of heritage prohibits or facilitates a sustainable feature of cultural landscapes as living sacred mountains
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