Mass‐velocity distributions of fragments in oblique impact cratering on gypsum     

Naomi Onose  Akira Fujiwara 《Meteoritics & planetary science》2004,39(2):321-331

Abstract— Oblique impact cratering experiments into gypsum targets were performed, and masses and velocities of the fragments were measured within the observational limit of 0.1–100 m/s in velocity and 0.0003–1 g in mass. The fragments observed were divided in two groups according to ejection time: early fragments ejected conically within a few msec after the impact followed by late fragments consisting of hundreds of slow, small fragments ejected almost perpendicular to the target. The relationship between mass and velocity of early fragments was observed to follow a power law with an exponent of ?0.11 ± 0.06, consistent with previous studies (e.g., Nakamura and Fujiwara 1991; Giblin et al. 1998). The cumulative number of fragments heavier or equal to a given mass versus fragment mass distributions shows a power law exponent of ?1.49 ± 0.09 for late fragments and steeper than ?0.49 ± 0.18 for early fragments. More than 10% of the mass was ejected from the crater with ejection speed slower than 2 m/s. Those fragments will reaccumulate on porous (<1500 kg/m³) and small (<4 km in diameter) asteroids.  相似文献   

The role of porous matrix in water flow regulation within a karst unsaturated zone: an integrated hydrogeophysical approach     

Simon D. Carrière  Konstantinos Chalikakis  Charles Danquigny  Hendrik Davi  Naomi Mazzilli  Chloé Ollivier  Christophe Emblanch 《Hydrogeology Journal》2016,24(7):1905-1918

Some portions of the porous rock matrix in the karst unsaturated zone (UZ) can contain large volumes of water and play a major role in water flow regulation. The essential results are presented of a local-scale study conducted in 2011 and 2012 above the Low Noise Underground Laboratory (LSBB – Laboratoire Souterrain à Bas Bruit) at Rustrel, southeastern France. Previous research revealed the geological structure and water-related features of the study site and illustrated the feasibility of specific hydrogeophysical measurements. In this study, the focus is on hydrodynamics at the seasonal and event timescales. Magnetic resonance sounding (MRS) measured a high water content (more than 10 %) in a large volume of rock. This large volume of water cannot be stored in fractures and conduits within the UZ. MRS was also used to measure the seasonal variation of water stored in the karst UZ. A process-based model was developed to simulate the effect of vegetation on groundwater recharge dynamics. In addition, electrical resistivity tomography (ERT) monitoring was used to assess preferential water pathways during a rain event. This study demonstrates the major influence of water flow within the porous rock matrix on the UZ hydrogeological functioning at both the local (LSBB) and regional (Fontaine de Vaucluse) scales. By taking into account the role of the porous matrix in water flow regulation, these findings may significantly improve karst groundwater hydrodynamic modelling, exploitation, and sustainable management.  相似文献   

The ecological and economic value of cold-water coral ecosystems     

Naomi S. Foley  Tom M. van Rensburg  Claire W. Armstrong 《Ocean & Coastal Management》2010,53(7):313-326

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Re-specifying disaster risk: concepts,methods, and models     

Naomi W. Lazarus 《GeoJournal》2014,79(5):635-648

The discussion on the social-ecological dimensions of hazards is constantly evolving. This paper explores the trajectory of research relating to hazards and their impact on vulnerable human populations. Interpretations of disaster risk have included estimating losses in terms of human life and property, and analyzing the social mechanisms in place that exacerbate or mitigate a population’s sensitivity to hazard events. In keeping with recent trends in research relating to disaster risk, the paper focuses on the social dimension of vulnerability and the contribution of social structures and relationships in building community resilience. Institutional frameworks and policies in particular determine the quantity and quality of resources and services available to people that contribute to resilience over time. The hazard-risk-location-model (HRLM) is proposed that is based on re-specifying disaster risk in terms of exposure and coping ability to capture the focus on social vulnerability and resilience. The framework of the HRLM incorporates the following components: (1) linkages within existing social capital; (2) spatial variation in social and institutional frameworks; (3) positive and negative feedbacks; and (4) characteristics of the hazard event. The model contributes to the range of place-based assessments designed to address the human-environmental impacts of hazards and disasters.  相似文献   

Messing with nature? Exploring public perceptions of geoengineering in the UK     

Adam Corner  Karen Parkhill  Nick Pidgeon  Naomi E. Vaughan 《Global Environmental Change》2013,23(5):938-947

Anthropogenic influence on the climate – and possible societal responses to it – offers a unique window through which to examine the way people think about and relate to the natural world. This paper reports data from four, one-day deliberative workshops conducted with members of the UK public during early 2012. The workshops focused on geoengineering – the deliberate, large-scale manipulation of the planetary environment – as one of three possible responses to climate change (alongside mitigation and adaptation). Here, we explore one of the most pervasive and wide-ranging themes to emerge from the workshops: whether geoengineering represented an unprecedented human intervention into ‘nature’, and what the moral consequences of this might be. Using the concept of ‘messing with nature’ as an analytical lens, we explore public perceptions of geoengineering. We also reflect on why ‘messing with nature’ was such a focal point for debate and disagreement, and whether the prospect of geoengineering may reveal new dimensions to the way that people think about the natural world, and their relationship to it.  相似文献   

Ten guiding principles for the delineation of priority habitat for endangered small cetaceans     

Peter S. Ross  Jay Barlow  Thomas A. Jefferson  Brendan E. Hickie  Tatiana Lee  Christina MacFarquhar  E. Christien Parsons  Kimberly N. Riehl  Naomi A. Rose  Elisabeth Slooten  Chia-Yang Tsai  John Y. Wang  Andrew J. Wright  Shih Chu Yang 《Marine Policy》2011

The adoption of endangered species laws in various nations has intensified efforts to better understand, and protect, at-risk species or populations, and their habitats. In many countries, delineating a portion of a species' habitat as particularly worthy of protection has become a mantra of these laws. Unfortunately, the laws themselves often provide scientists and managers with few, if any, guidelines for how to define such habitat. Conservationists and scientists may view protecting part of the habitat of an endangered species as an ineffectual compromise, while managers may be under pressure to allow a range of human activities within the species' habitat. In the case of small cetaceans, establishing boundaries for such areas can also be complicated by their mobility, the fluid nature of their environment, and the often ephemeral nature of their habitat features. The convergence of multiple human impacts in coastal waters around the world is impacting many small cetaceans (and other species) that rely on these areas for feeding, reproducing, and resting. The ten guiding principles presented here provide a means to characterize the habitat needs of small, at-risk cetaceans, and serve as a basis for the delineation of ‘priority habitat’ boundaries. This conceptual approach should facilitate a constructive discourse between scientists and managers engaged in efforts to recover endangered species. The degree to which the recovery of an at-risk species can be reconciled with sustainable economic activity will depend in part on how well these principles are incorporated into the delineation of priority habitat.  相似文献   

The rise and fall of the Irish orange roughy fishery: An economic analysis     

Naomi S. Foley  Tom M. van Rensburg  Claire W. Armstrong 《Marine Policy》2011

An Irish commercial fishery for orange roughy began in the Northeast Atlantic in 2001 with the assistance of government grants. The fishery began as an open access, non-quota fishery. The rapid boom and bust of many deep water fisheries was experienced. Landings peaked in 2002 and then dropped significantly the following year. Many vessels were forced out of the fishery due to high costs and rapidly declining stocks. By 2005 the fishery was largely closed. Applying a bioeconomic analysis, this paper shows why the fishery no longer exists and discusses both the external and opportunity costs of the fishery. A bioeconomic model is applied to the available data to assess the open access effort and harvest with and without government grant aid. The results suggest that in the absence of subsidies, deep water trawling would not have been viable. In addition to the financial costs such as high fuel consumption, there are also externalities associated with deep water trawling. Orange roughy is closely associated with deep water ecosystems such as seamounts and cold water corals. This paper examines the costs of damage to cold water corals. These costs include the loss of fish habitats and lost future use and preservation values.  相似文献   

A review of climate geoengineering proposals   总被引：2，自引：0，他引：2  

Naomi E. Vaughan  Timothy M. Lenton 《Climatic change》2011,109(3-4):745-790

Climate geoengineering proposals seek to rectify the current radiative imbalance via either (1) reducing incoming solar radiation (solar radiation management) or (2) removing CO₂ from the atmosphere and transferring it to long-lived reservoirs (carbon dioxide removal). For each option, we discuss its effectiveness and potential side effects, also considering lifetime of effect, development and deployment timescale, reversibility, and failure risks. We present a detailed review that builds on earlier work by including the most recent literature, and is more extensive than previous comparative frameworks. Solar radiation management propsals are most effective but short-lived, whilst carbon dioxide removal measures gain effectiveness the longer they are pursued. Solar radiation management could restore the global radiative balance, but must be maintained to avoid abrupt warming, meanwhile ocean acidification and residual regional climate changes would still occur. Carbon dioxide removal involves less risk, and offers a way to return to a pre-industrial CO₂ level and climate on a millennial timescale, but is potentially limited by the CO₂ storage capacity of geological reservoirs. Geoengineering could complement mitigation, but it is not an alternative to it. We expand on the possible combinations of mitigation, carbon dioxide removal and solar radiation management that might be used to avoid dangerous climate change.  相似文献   

源自海洋的地震风险     

Naomi Lubick  左玉玲 《国际地震动态》2011,(10):9-11

某些最强的地震源自遥远的海底断层。目前,地球物理学家正在铺设传感器网络,以密切监视这些"潜伏杀手"的动态。  相似文献   

User fees and the permeability of public space at municipal pools and bathhouses in New York City, 1870 – present     

Naomi Adiv  Laura Wolf-Powers 《Urban geography》2013,34(8):1071-1096

This paper examines fees for access to New York City’s public swimming and bathing spaces from 1870 to the present. We argue that, beyond generating revenue and rationing space, charges for admission to public bathing spaces have served to condition how permeable those spaces were to various groups of potential users. Municipal actors involved in administering baths and pools have used fees to maintain and order these spaces; to distinguish between deserving and undeserving users; and to include and exclude participants in an ostensibly universal public. Over time, fees have been naturalized, erasing these motivations and giving cause to their outcomes. We problematize the fee in order to address both theoretical questions about the nature of public space and practical ones about how municipal administrators govern amidst competing pressures to serve, develop and regulate urban residents and their communities.  相似文献