5,597 research outputs found
The Decline and Fall of the Osgiliathian Empire
Taking Tolkien’s statement that hobbits lingered in “the North-West of the Old World” as its basis, this paper examines the fauna, organization of human culture, development of armor and so on in Middle-earth to place it in the “heroic age” of Europe and to identify Gondor with Rome. The author further identifies the function of the Elves and their protected kingdoms with the monasteries that preserved cultural memories through the Dark Ages. Consideration is given to the nonmedieval culture of the Shire, the fact that Aragorn does not map precisely onto any particular ruler of this period, and what these anomalies mean
Less government intervention in biodiversity management: risks and opportunities
n a changing global environment, with increasing pressure on ecosystem goods and services, biodiversity conservation is likely to become increasingly important. However, with the current global financial crisis, governments are increasingly trying to stabilise economies through spending cuts aiming to reduce national deficits. Within such an economic climate, the devolution of governance through public participation is an intrinsically appealing concept. We outline a number of challenges that explain why increased participation in biodiversity management has been and may continue to be problematic. Using as a case study the local stakeholder-driven Moray Firth Seal Management Plan in Scotland, we identify four key conditions that were crucial to the successful participatory management of a biodiversity conflict: a local champion, the emergence of a crisis point, the involvement of decision-makers, and long-term financial and institutional support. Three of the four conditions point to the role of direct government involvement, highlighting the risk of devolving responsibility for biodiversity conflict management to local communities. We argue that without an informed debate, the move towards a more participatory approach could pose a danger to hard-won policy gains in relation to public participation, biodiversity conservation and conflict management
A class of non-binary matroids with many binary minors
It is a well-known result of Tutte, A homotopy theorem for matroids, I, II, Trans. Amer. Math. Soc. 88 (1958) 144-174. that U2,4 is the only non-binary matroid M such that, for every element e, both M\e and M/e are binary. Oxley generalized this result by characterizing the non-binary matroids M such that, for every element e of M, the deletion M\e or the contraction M/e is binary. We characterize those non-binary matroids M such that, for all elements e and f, at least two of M\e, f; M\e/f; M/e\f; and M/e, f are binary. © 1999 Elsevier Science B.V. All rights reserved
Sound propagation over uneven ground and irregular topography
The goal of this research is to develop theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography here is understood to imply a ground surface that is not idealizable as being perfectly flat or that is not idealizable as having a constant specific acoustic impedance. The interest of this study focuses on circumstances where the propagation is similar to what might be expected for noise from low-attitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence. The activities and developments that have resulted during the period, August 1986 through February 1987, are discussed
Sound propagation over uneven ground and irregular topography
Theoretical, computational, and experimental techniques were developed for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography is understood to imply a ground surface that: (1) is not idealizable as being perfectly flat, or (2) that is not idealizable as having a constant specific acoustic impedance. The focus is on circumstances where the propagation is similar to what might be expected for noise from low altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence
Rigorous numerics for analytic solutions of differential equations : the radii polynomial approach
Judicious use of interval arithmetic, combined with careful pen
and paper estimates, leads to effective strategies for computer assisted analysis
of nonlinear operator equations. The method of radii polynomials is an
efficient tool for bounding the smallest and largest neighborhoods on which
a Newton-like operator associated with a nonlinear equation is a contraction
mapping. The method has been used to study solutions of ordinary, partial,
and delay differential equations such as equilibria, periodic orbits, solutions
of initial value problems, heteroclinic and homoclinic connecting orbits in the
Ck category of functions. In the present work we adapt the method of radii
polynomials to the analytic category. For ease of exposition we focus on studying
periodic solutions in Cartesian products of infinite sequence spaces. We
derive the radii polynomials for some specific application problems and give a
number of computer assisted proofs in the analytic framework
New Doppler echocardiographic applications for the study of diastolic function
AbstractDoppler echocardiography is one of the most useful clinical tools for the assessment of left ventricular (LV) diastolic function. Doppler indices of LV filling and pulmonary venous (PV) flow are used not only for diagnostic purposes but also for establishing prognosis and evaluating the effect of therapeutic interventions. The utility of these indices is limited, however, by the confounding effects of different physiologic variables such as LV relaxation, compliance and filling pressure. Since alterations in these variables result in changes in Doppler indices of opposite direction, it is often difficult to determine the status of a given variable when a specific Doppler filling pattern is observed. Recently, color M-mode and tissue Doppler have provided useful insights in the study of diastolic function. These new Doppler applications have been shown to provide an accurate estimate of LV relaxation and appear to be relatively insensitive to the effects of preload compensation. This review will focus on the complementary role of color M-mode and tissue Doppler echocardiography and traditional Doppler indices of LV filling and PV flow in the assessment of diastolic function
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Black carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons
Black carbon (BC) is known to have major impacts on both climate and human health and is therefore of global importance, particularly in regions close to large populations that have strong sources. The size-resolved mixing state of BC-containing particles was characterised using a single-particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain (IGP) during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11 and 12 June) and monsoon (30 June to 11 July) seasons of 2016.
Over the IGP, BC mass concentrations were greater (1.95 µg m−3) compared to north-west India (1.50 µg m−3) and north-east India (0.70 µg m−3) during the pre-monsoon season. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter <0.16 µm and coating thickness <50 nm) and a mode of moderately coated BC (core diameter <0.22 µm and coating thickness of 50–200 nm). The IGP and north-east India locations exhibited moderately coated black carbon particles with enhanced coating thicknesses, core sizes, mass absorption cross sections, and scattering enhancement values compared to much lower values present in the north-west. The coating thickness and mass absorption cross section increased with altitude (13 %) compared to those in the boundary layer. As the monsoon arrived across the region, mass concentration of BC decreased over the central IGP and north-east locations (38 % and 28 % respectively), whereas for the north-west location BC properties remained relatively consistent. Post-monsoon onset, the coating thickness, core size, mass absorption cross section, and scattering enhancement values were all greatest over the central IGP much like the pre-monsoon season but were considerably reduced over both north-east and north-west India. Increases in mass absorption cross section through the atmospheric column were still present during the monsoon for the north-west and central IGP locations, but less so over the north-east due to lack of long-range transport aerosol aloft. Across the Indo-Gangetic Plain and north-east India during the pre-monsoon and monsoon seasons, solid-fuel (wood burning) emissions form the greatest proportion of BC with moderately coated particles. However, as the monsoon develops in the north-east there was a switch to small uncoated BC particles indicative of traffic emissions, but the solid-fuel emissions remained in the IGP into the monsoon. For both seasons in the north-west, traffic emissions form the greatest proportion of BC particles.
Our findings will prove important for greater understanding of the BC physical and optical properties, with important consequences for the atmospheric radiative forcing of BC-containing particles. The findings will also help constrain the regional aerosol models for a variety of applications such as space-based remote sensing, chemistry transport modelling, air quality, and BC source and emission inventories
Design of a Direct-Detection Wind and Aerosol Lidar for Mars Orbit
The present knowledge of the Mars atmosphere is greatly limited by a lack of global measurements of winds and aerosols. Hence, measurements of height-resolved wind and aerosol profiles are a priority for new Mars orbiting missions. We have designed a direct-detection lidar (MARLI) to provide global measurements of dust, winds and water ice profiles from Mars orbit. From a 400-km polar orbit, the instrument is designed to provide wind and backscatter measurements with a vertical resolution of 2 km and with resolution of 2 in latitude along track. The instrument uses a single-frequency, seeded Nd:YAG laser that emits 4 mJ pulses at 1064 nm at a 250 Hz pulse rate. The receiver utilizes a 50-cm diameter telescope and a double edge Fabry-Prot etalon as a frequency discriminator to measure the Doppler shift of the aerosol-backscatter profiles. The receiver also includes a polarization-sensitive channel to detect the cross-polarized backscatter profiles from water ice. The receiver uses a sensitive 4 4 pixel HgCdTe avalanche photodiode array as a detector for all signals. Here we describe the measurement concept, instrument design, and calculate its performance for several cases of Mars atmospheric conditions. The calculations show that under a range of atmospheric conditions MARLI is capable of measuring wind speed profiles with random error of 24 m/s within the first three scale heights, enabling vertically resolved mapping of transport processes in this important region of the atmosphere
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