205 research outputs found

    Income Tax Avoidance and Evasion: A Narrow Bracketing Approach

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    We characterize optimal individual tax evasion and avoidance when taxpayers ìnarrow bracketî the joint avoidance/evasion decision by exhausting all gainful methods for legal avoidance before choosing whether or not also to evade illegally. We Önd that (i) evasion is an increasing function of the audit probability when the latter is low enough, yet tax avoidance is always decreasing in the probability of audit; (ii) an analogous Önding to the so-called Yitzhaki puzzle for evasion also holds for tax avoidance ñan increase in the tax rate decreases the level of avoided income and the level of avoided tax; and (iii) that, holding constant the expected return to evasion, it is not always the case that the combined loss of reported income due to avoidance and evasion can be stemmed by increasing the Öne rate and decreasing the audit probability

    A Perspective on Economic Impact

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    The institutions responsible for water resources management in the United States have originated as political responses to major social issues. Each agency institutionalized a procedure for structuring and comparing alternatives in the formulation of its total program. Each agency originally sought to promote effective resolution of its social issue (flood control, development of arid lands, soil erosion, etc.), but more recent efforts have sought better coordination among agency practices through a common procedure largely derived from economic theory. Any procedure, however, varies in application with the interpretation and judgment of individual planners. Today, public pressures have brought political directives requiring consideration of the local and nationwide impacts of projects that occur through direct, indirect, and secondary means in the spheres of economic, social and environmental effects. The body of the study reviews fourteen specific impact issues with the goals of providing planners a methodology for dealing with each one and of providing the theoretically inclined a basis for improving each methodology. The issues are reservoir effects on local property values, reservoir effects on the economy of the local county, changes in income and employment patterns around large reservoirs, patterns of land use change around reservoirs, reservoir effects on revenues and expenditures of local government, reservoir recreation benefits, application of marginal economic analysis to reservoir recreation planning, economic value of natural areas for recreational hunting, for stream fishing, the personal value of real property to its owner, reservoir project caused income redistribution, achievement of more flexible procedures for reservoir operation in order to match changes in demand for project output with time, estimation of flood damages by the time pattern in which they occur, and operation of reservoir systems for flood control. Each study ls presented in detail in a referenced report, and this report discusses the significance of the findings of the studies, individually and as a group

    A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

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    Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from far-field records1-3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution

    The last forests on Antarctica: Reconstructing flora and temperature from the Neogene Sirius Group, Transantarctic Mountains

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    Fossil-bearing deposits in the Transantarctic Mountains, Antarctica indicate that, despite the cold nature of the continent’s climate, a tundra ecosystem grew during periods of ice sheet retreat in the mid to late Neogene (17–2.5 Ma), 480 km from the South Pole. To date, palaeotemperature reconstruction has been based only on biological ranges, thereby calling for a geochemical approach to understanding continental climate and environment. There is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm-conifer vegetation, or whether by this point conifers had disappeared from the continent. In order to address these questions, we have analysed, for the first time in sediments of this age, plant and bacterial biomarkers in terrestrial sediments from the Transantarctic Mountains to reconstruct past temperature and vegetation during a period of East Antarctic Ice Sheet retreat. From tetraether lipids (MBT’/CBT palaeothermometer), we conclude that the mean continental summer temperature was ca. 5 °C, in agreement with previous reconstructions. This was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter. Biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants, moss and algal mats growing in microenvironments in a glacial outwash system. Abietane-type compounds were abundant in some samples, indicating that conifers, most likely Podocarpaceae, grew on the Antarctic continent well into the Neogene. This is supported by the palynological record, but not the macrofossil record for the continent, and has implications for the evolution of vegetation on Antarctica

    Holocene dynamics of the Southern Hemisphere westerly winds and possible links to CO2 outgassing

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    The Southern Hemisphere westerly winds (SHW) play an important role in regulating the capacity of the Southern Ocean carbon sink. They modulate upwelling of carbon-rich deep water and, with sea ice, determine the ocean surface area available for air–sea gas exchange. Some models indicate that the current strengthening and poleward shift of these winds will weaken the carbon sink. If correct, centennial- to millennial-scale reconstructions of the SHW intensity should be linked with past changes in atmospheric CO2, temperature and sea ice. Here we present a 12,300-year reconstruction of wind strength based on three independent proxies that track inputs of sea-salt aerosols and minerogenic particles accumulating in lake sediments on sub-Antarctic Macquarie Island. Between about 12.1 thousand years ago (ka) and 11.2 ka, and since about 7 ka, the wind intensities were above their long-term mean and corresponded with increasing atmospheric CO2. Conversely, from about 11.2 to 7.2 ka, the wind intensities were below their long-term mean and corresponded with decreasing atmospheric CO2. These observations are consistent with model inferences of enhanced SHW contributing to the long-term outgassing of CO2 from the Southern Ocean

    Mid- to late Pliocene (3.3-2.6 Ma) global sea-level fluctuations recorded on a continental shelf transect, Whanganui Basin, New Zealand

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    We present a similar to 900 m-thick, mid- (3.3-3.0 Ma) to late Pliocene (3.0-2.6 Ma), shallow-marine, cyclical sedimentary succession from Whanganui Basin, New Zealand that identifies paleobathymetric changes, during a warmer-than-present interval of Earth history, relevant to future climate change. Our approach applies lithofacies, sequence stratigraphy and benthic foraminiferal analyses to two continuously-cored drillholes integrated with new and existing outcrop studies. We construct a depositional model of orbitally-paced, global sea-level changes on a wave-graded continental shelf. Unlike many previous studies, these shelf sediments were not eroded during sea-level lowstands and thus provide the potential to reconstruct the full amplitude of glacial-interglacial sea-level change. Paleobathymetric interpretations are underpinned by analysis of extant benthic foraminiferal census data and a statistical correlation with the distribution of modern taxa. In general, water depths derived from foraminiferal Modern Analogue Technique (MAT), are consistent with variability recorded by lithofacies. The inferred sea-level cycles co-vary with a qualitative climate record reconstructed from a census of extant pollen and spores, and a modern temperature relationship. A high -resolution age model is established using magnetostratigraphy constrained by biostratigraphy, and the dating and correlation of tephra. This integrated chronostratigraphy allows the recognition of 23 individual sedimentary cycles, that are correlated across the paleo-shelf and a possible "one-to-one" relationship is made to deep-ocean benthic oxygen isotope (delta O-18) records. In general water depth changes were paced by similar to 20 kyr duration between 3.3 and 3.0 Ma, after which cycle duration is similar to 40 kyr during the late Pliocene (3.0-2.6 Ma). This record provides a future opportunity to evaluate the amplitude and frequency of global, Pliocene glacioeustatic sea-level change, independent of the global benthic delta O-18 record. (C) 2018 Elsevier Ltd. All rights reserve

    Molecular Imaging of Pulmonary Tuberculosis in an Ex-Vivo Mouse Model Using Spectral Photon-Counting Computed Tomography and Micro-CT

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    Assessment of disease burden and drug efficacy is achieved preclinically using high resolution micro computed tomography (CT). However, micro-CT is not applicable to clinical human imaging due to operating at high dose. In addition, the technology differences between micro-CT and standard clinical CT prevent direct translation of preclinical applications. The current proof-of-concept study presents spectral photon-counting CT as a clinically translatable, molecular imaging tool by assessing contrast uptake in an ex-vivo mouse model of pulmonary tuberculosis (TB). Iodine, a common contrast used in clinical CT imaging, was introduced into a murine model of TB. The excised mouse lungs were imaged using a standard micro-CT subsystem (SuperArgus) and the contrast enhanced TB lesions quantified. The same lungs were imaged using a spectral photoncounting CT system (MARS small-bore scanner). Iodine and soft tissues (water and lipid) were materially separated, and iodine uptake quantified. The volume of the TB infection quantified by spectral CT and micro-CT was found to be 2.96 mm(3) and 2.83 mm(3), respectively. This proof-of-concept study showed that spectral photon-counting CT could be used as a predictive preclinical imaging tool for the purpose of facilitating drug discovery and development. Also, as this imaging modality is available for human trials, all applications are translatable to human imaging. In conclusion, spectral photon-counting CT could accelerate a deeper understanding of infectious lung diseases using targeted pharmaceuticals and intrinsic markers, and ultimately improve the efficacy of therapies by measuring drug delivery and response to treatment in animal models and later in humans

    Undersea Constellations: The Global Biology of an Endangered Marine Megavertebrate Further Informed through Citizen Science

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    The whale shark is an ideal flagship species for citizen science projects because of its charismatic nature, its size, and the associated ecotourism ventures focusing on the species at numerous coastal aggregation sites. An online database of whale shark encounters, identifying individuals on the basis of their unique skin patterning, captured almost 30,000 whale shark encounter reports from 1992 to 2014, with more than 6000 individuals identified from 54 countries. During this time, the number of known whale shark aggregation sites (hotspots) increased from 13 to 20. Examination of photo-identification data at a global scale revealed a skewed sex-ratio bias toward males (overall, more than 66%) and high site fidelity among individuals, with limited movements of sharks between neighboring countries but no records confirming large, ocean basin-scale migrations. Citizen science has been vital in amassing large spatial and temporal data sets to elucidate key aspects of whale shark life history and demographics and will continue to provide substantial long-term value
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