332,290 research outputs found

    Ventilation and cave air PCO2 in the Bunker-Emst Cave System (NW Germany): implications for speleothem proxy data

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    Cave air pCO2 (carbon dioxide partial pressure) is, along with drip rate, one of the most important factors controlling speleothem carbonate precipitation. As a consequence, pCO2 has an indirect but important control on speleothem proxy data (e.g., elemental concentrations, isotopic values). The CO2 concentration of cave air depends on CO2 source(s) and productivity, CO2 transport through the epikarst and karst zone, and cave air ventilation. To assess ventilation patterns in the Bunker-Emst Cave (BEC) System, we monitored the pCO2 value approximately 100 m from the lower entrance (Bunker Cave) at bi-hourly resolution between April 2012 and February 2014. The two entrances of the BEC system were artificially opened between 1860?1863 (Emst Cave) and 1926 (Bunker Cave). Near-atmospheric minimum pCO2dynamics of 408 ppmv are measured in winter, and up to 811 ppmv are recorded in summer. Outside air contributes the highest proportion to cave air CO2, while soil, and possibly also ground air, provide a far smaller proportion throughout the whole year. Cave air pCO2 correlates positively with the temperature difference between surface and cave air during summer and negatively in winter, with no clear pattern for spring and autumn. Dynamic ventilation is driven by temperature and resulting density differences between cave and surface air. In summer, warm atmospheric air is entrained through the upper cave entrance where it cools. With increasing density, the cooled air flows toward the lower entrance. In winter, this pattern is reversed, due to cold, atmospheric air entering the cave via the lower entrance, while relatively warm cave air rises and exits the cave via the upper entrance. The situation is further modulated by preferential south-southwestern winds that point directly on both cave entrances. Thus, cave ventilation is frequently disturbed, especially during periods with higher wind speed. Modern ventilation of the BEC system-induced by artificially openings-is not a direct analogue for pre-1860 ventilation conditions. The artificial change of ventilation resulted in a strong increase of ?13Cspeleothem values. Prior to the cave opening in 1860, Holocene ?13Cspeleothem values were significantly lower, probably related to limited ventilation due to the lack of significant connections between the surface and cave. Reduced ventilation led to significantly higher pCO2 values, minimal CO2 degassing from drip water and low kinetic isotope fractionation. Both modern and fossil speleothem precipitation rates are driven by water supply and carbonate saturation, and not by cave air pCO2. Today, pCO2 variability is too small to affect carbonate precipitation rates and the same is likely true for pCO2 variability prior to artificial opening of the cave. Thus, fossil speleothems from BEC System are likely more sensitive to temperature and infiltration dynamics. The Bunker-Emst Cave System, therefore, represents different ventilation patterns and their influence on speleothem proxy data in an exemplary manner, and it may serve as a template for other cave systems

    Improved Attack on the Cellular Authentication and Voice Encryption Algorithm

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    We present new cryptanalysis of the Telecommunications hash algorithm known as Cellular Authentication and Voice Encryption Algorithm (CAVE). The previous guess-and-determine style reconstruction attack requires 2912^{91} (resp. 2932^{93}) evaluations of CAVE-4 (resp. CAVE-8) to find a single valid pre-image (one which satisfies the input redundancy). Here we present a new attack that finds emph{all} valid pre-images with effort equivalent to around 2722^{72} evaluations of the algorithm for both CAVE-4 and CAVE-8

    Female mating preferences in blind cave tetras Astyanax fasciatus (Characidae, Teleostei).

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    The Mexican tetra Astyanax fasciatus has evolved a variety of more or less color- and eyeless cave populations. Here we examined the evolution of the female preference for large male body size within different populations of this species, either surface- or cave-dwelling. Given the choice between visual cues from a large and a small male, females from the surface form as well as females from an eyed cave form showed a strong preference for large males. When only non-visual cues were presented in darkness, the surface females did not prefer either males. Among the six cave populations studied, females of the eyed cave form and females of one of the five eyeless cave populations showed a preference for large males. Apparently, not all cave populations of Astyanax have evolved non-visual mating preferences. We discuss the role of selection by benefits of non-visual mate choice for the evolution of non-visual mating preferences

    Taxonomical revision of the Late Würm Sorex (Mammalia, Insectivora) remains of Hungary, for proving the presence of an alpine ecotype in the Pilisszántó Horizon

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    Fossil bone assemblages of 14 localities, ranged in the Pilisszántó Horizon (Late Würm), are stored in the collection of the Geological Museum of Hungary and Hungarian Natural History Museum. Sorex araneus findings were reported from five of them (Balla Cave, Bivak Cave, Peskő Cave, Petényi Cave, Pilisszántó Shelter). Taxonomic revision of S. araneus showed that several specimens belong to S. alpinus in Balla Cave and Petényi Cave. The presence of this form, supported by other Boreo-Alpine fauna elements, indicates not only a significantly cold climate in the Pilisszántó Horizon, but the development of a special ecotype in the named localities. However. as the sites are only 400–800 m above see level, mountainous relief and periglacial climate yielded open mountain vegetation above the zone of pine forests

    GLOBE Cave Protocol Field Guide: Comparing Surface and Subterranean Environments

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    The GLOBE Cave Protocol Field Guide utilizes existing GLOBE protocols to explore an extreme environment. Caves provide an opportunity to utilize GLOBE protocols to investigate underground environments and compare them to surface environments. Outside the cave, students record elevation, MUC, latitude and longitude, air temperature, relative humidity and air pressure. Inside the cave, students record air temperature, relative humidity and air pressure as well as observe and describe cave features in each room. Students also note evidence of biological activity and human impact. If water is present inside the cave, students record water temperature and pH. Follow up questions are included in the Field Guide. Educational levels: Middle school, High school, Intermediate elementary

    The Cyrilka Cave-the longest crevice-type cave in Czechia: structural controls, genesis, and age

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    The Cyrilka Cave is the second longest pseudokarst cave and the longest crevice-type cave in Czechia. Developed within the headscarp area of a deep-seated landslide, the cave became a focus of scientific research in recent years when new passages were discovered. Structural analysis provided a general tectonic plan of the cave, as well as more detailed data on geometry and kinematics of the relaxed rock massif. The primary structure of NNE- to ENE-striking bedding is broken by a system of NNE-striking fissures interconnected by two continuous ENE-striking dextral fracture zones. Abundant signs of recent sinistral strike-slips within the rock massif represent a bold structural feature of the cave. Along with DEM imaging and a detailed survey of the cave, 2-D and 3-D ERT measurements completed an image of the main predispositions and revealed the internal structure of the slope deformation. These measures also detected unknown crevices above the existing headscarp, which indicate the retrograde evolution of the landslide. Methodologically, we used the 3-D electrical resistivity tomography in the incoherent sedimentary flysch rocks for the first time. Based on radiocarbon dating of the stalactite core, the minimum age of the cave is up to 19,900 +/- 280 cal BP, which is the oldest age detected in the area of the Outer Flysch Carpathians so far; we thoroughly discuss further indirect evidence indicating a probable Late Pleistocene age of the cave.Web of Science47339237

    Revisiting Qumran Cave 1Q and its archaeological assemblage

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    Qumran Cave 1Q was the first site of Dead Sea scroll discoveries. Found and partly emptied by local Bedouin, the cave was excavated officially in 1949 and published in the series Discoveries in the Judaean Desert (Volume 1) in 1955. Contents of the cave are found in collections worldwide, and in different institutions in Jerusalem and Amman. While the scrolls are the most highly prized artefacts from this cave, in archaeological terms they are part of an assemblage that needs to be understood holistically in order to make conclusions about its character and dating. This study presents all of the known items retrieved from the cave, including those that are currently lost, in order to consider what we might know about the cave prior to its emptying and the changes to its form. It constitutes preliminary work done as part of the Leverhulme funded International Network for the Study of Dispersed Qumran Caves Artefacts and Archival Sources [IN-2015-067].peer-reviewe

    The perceptions of SME owner-managers relating to ethics and online business practices : a thesis presented in partial fulfillment of the requirements for the degree of Master of Management in Management at Massey University

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    The Internet has created many new opportunities for small-to-medium sized enterprises (SMEs) and many of these firms are encountering external pressure to have an online presence. E-commerce, however, brings a series of ethical challenges for many businesses, notably issues relating to privacy and security. These ethical challenges need to be met by SME owner-managers in order to ensure that their business competes and survives in today's hyper-competitive environment. To date, there is very little research on ethics and online business, and the focus of this study was to investigate ethical perceptions of SME owner-managers relating to online business practices. The study was qualitative in nature and involved semi-structured interviews with twelve owner-managers of Wellington based SMEs that had an online presence. The exploratory nature of the study meant that rich data was obtained from the twelve interviewees and the findings were grouped into three main themes for discussion, the importance of e-commerce, the underlying values and risk-tolerance of the participant owner-manager and, participant perception of ethical online issues such as privacy, security, intellectual property (IP) and online trust. The importance of e-commerce both now and in the future was highlighted by the owner-managers, and there was also a diverse range of ethical concerns that they had with online business. These findings and subsequent discussion allowed for some interesting conclusions to be made. The complex changing nature of online ethics is highlighted, as well the notion that stakeholders have an important influence on the online ethical framework. This study also concludes that there is a gap between current legislation and an awareness of how this impacts on the owner-managers business. There is also a 'disconnect' between thought and action on the part of the owner-manager in terms addressing some of their online ethical concerns

    Invertebrate Fauna of Devils Den, a Sandstone Cave in Northwestern Arkansas

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    The same invertebrate fauna of 17 species was found in Devils Den Cave, Washington County, Arkansas, in 1969 and 1979. The fauna consists of 1 trogloxene, 14 troglophiles, and 2 troglobites, a spider, Porrhomma cavernicolum, and a collembolan, Pseudosinella dubia. Devils Den Cave has a well developed cavernicolous fauna, although it is in sandstone which generally supports a poor cave adapted fauna. The troglobites probably evolved in the vicinity of northwestern Arkansas in limestone caves or in deep forest soils of the Ozark region. They then dispersed overland, perhaps as recently as the late Wisconsinan, to occupy this sandstone cave

    Cavefish Population Status and Environmental Quality in Cave Springs Cave, Arkansas - Final Report submitted to Arkansas Natural Heritage Commission

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    This report summarizes the continuing effort to monitor environmental quality in the Cave Springs Cave Natural Area and to implement the Ozark Cavefish Recovery Plan. Last year’s report (Brown et al., 1998) identified certain environmental stressors, including a trend over 15 years of increasing nutrient pollution, a low cavefish population count of only 106, and the presence of heavy metals in the cave water and one semi-volatile organic compound (the phthalate DEHP at 500 ppb) in resident crayfish tissue. This year’s monitoring effort demonstrates that fecal coliforms continue to exceed Arkansas State Water Quality Standards (Regulation 2), sometimes by a factor of 1000. The presence of heavy metals is confirmed, in not only the cave water and sediments, but in crayfish tissue, which implies that it may be bioaccumulating in the cave foodweb. Furthermore, beryllium, copper, lead, selenium, and zinc are present in concentrations in the cave water that exceeded the Regulation 2 standards for chronic, and sometimes acute, toxicity to aquatic life. Significant amounts of nitrate are also present (with a yearly average of over 5 mg NO3-N/ L), and phosphate concentrations occasionally exceed Regulation 2 standards. Concentrations of nitrate, ortho-phosphate, total phosphate, total coliforms, and several dissolved metals (Al, Ba, Cu, Fe, and Pb) were all highly correlated with discharge, and concentrations were highest during stormflow events. No pesticides were detected in cave water, crayfish tissue or bat guano. Phthalates were again detected in crayfish tissue (DEP and DEHP at 1 ppb each), as well as the cave water (DEHP at 0.7 ppb). While the effects of these phthalates upon aquatic organisms are unknown, the U. S. Environmental Protection Agency considers phthalates to be human carcinogens and hormone disrupters. Ironically, while the cavefish habitat appears to be quite polluted, this year’s population survey counted 166 Ozark cavefish, the most ever counted for this (or any other) habitat. In order to integrate these pollution concerns and other data about this cave complex, a geographic information system was created for the Cave Springs Cave recharge zone. Preliminary analyses have detected several sensitive areas and pollution sources. The cave complex was determined to extend outside of the Natural Area boundary, and several sinkholes were identified. Photo-lineaments and fracture traces were identified, and other studies in Benton County demonstrate that these features, commonly expressed as intermittent streams on the surface, allow surface pollutants to rapidly enter the groundwater. Protection of these adjacent lands, sinkholes, and streams is recommended. The reduction or cessation of the land application of sewage sludge and agricultural waste in the recharge zone is also recommended
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