نتایج جستجو برای: anthropogenic factors

تعداد نتایج: 1098792  

Journal: :Proceedings. Biological sciences 2005
Tadashi Fukami David A Wardle

Many ecological dynamics occur over time-scales that are well beyond the duration of conventional experiments or observations. One useful approach to overcome this problem is extrapolation of temporal dynamics from spatial variation. We review two complementary variants of this approach that have been of late increasingly employed: the use of natural gradients to infer anthropogenic effects and...

Journal: :The Science of the total environment 2004
José H García Wen-Whai Li Richard Arimoto Richard Okrasinski Janet Greenlee John Walton Cheryl Schloesslin Sondra Sage

A series of analyses were performed to provide chemical signatures for surface soils and to evaluate potential sources of fugitive dust in the Paso del Norte (PdN) region. Eighteen sites were selected for soil sampling based on an assessment of the soil types in the region and the main upwind source areas with a potential for wind erosion. Analyses of the soil samples provided chemical 'fingerp...

2017
Tibor Magura Gábor L Lövei Béla Tóthmérész

Most edges are anthropogenic in origin, but are distinguishable by their maintaining processes (natural vs. continued anthropogenic interventions: forestry, agriculture, urbanization). We hypothesized that the dissimilar edge histories will be reflected in the diversity and assemblage composition of inhabitants. Testing this "history-based edge effect" hypothesis, we evaluated published informa...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Robert K Kaufmann Heikki Kauppi Michael L Mann James H Stock

Given the widely noted increase in the warming effects of rising greenhouse gas concentrations, it has been unclear why global surface temperatures did not rise between 1998 and 2008. We find that this hiatus in warming coincides with a period of little increase in the sum of anthropogenic and natural forcings. Declining solar insolation as part of a normal eleven-year cycle, and a cyclical cha...

2016
Ilia Rochlin Ary Faraji Dominick V. Ninivaggi Christopher M. Barker A. Marm Kilpatrick

The recent emergence and spread of vector-borne viruses including Zika, chikungunya and dengue has raised concerns that climate change may cause mosquito vectors of these diseases to expand into more temperate regions. However, the long-term impact of other anthropogenic factors on mosquito abundance and distributions is less studied. Here, we show that anthropogenic chemical use (DDT; dichloro...

2017
Rick Bruintjes Harry R Harding Tom Bunce Fiona Birch Jessica Lister Ilaria Spiga Tom Benson Kate Rossington Diane Jones Charles R Tyler Andrew N Radford Stephen D Simpson

Empirical investigations of the impacts of anthropogenic stressors on marine organisms are typically performed under controlled laboratory conditions, onshore mesocosms, or via offshore experiments with realistic (but uncontrolled) environmental variation. These approaches have merits, but onshore setups are generally small sized and fail to recreate natural stressor fields, whereas offshore st...

2015
Maria Tzortziou Christina Zeri Elias Dimitriou Yan Ding Rudolf Jaffé Emmanouil Anagnostou Elli Pitta Angeliki Mentzafou

Most transboundary rivers and their wetlands are subject to considerable anthropogenic pressures associated with multiple and often conflicting uses. In the Eastern Mediterranean such systems are also particularly vulnerable to climate change, posing additional challenges for integrated water resources management. Comprehensive measurements of the optical signature of colored dissolved organic ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد - دانشکده ادبیات و علوم انسانی 1394

abstract previous studies on willingness to communicate (wtc) have shown the influence of many individual or situational factors on students’ tendency to engage in classroom communication, in which wtc has been viewed either at the trait-level or situational level. however, due to the complexity of the notion of willingness to communicate, the present study suggests that these two strands are ...

2010
Esther Coz Gary Casuccio Traci L. Lersch Teresa Moreno

Mineral dust is a contributor of the global aerosol budget, with arid regions as principal sources. IPCC (2007) gives a best estimate of the direct mineral dust radiative forcing (RF), with the highest uncertainty in the radiative balance estimations being associated to mineral dust for both its direct and indirect effects. In addition, differentiating the anthropogenic influenced dust has impo...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده فنی مهندسی 1388

the purpose of this study is identifying effective factors which make customers shop online in iran and investigating the importance of discovered factors in online customers’ decision. in the identifying phase, to discover the factors affecting online shopping behavior of customers in iran, the derived reference model summarizing antecedents of online shopping proposed by change et al. was us...

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