‘Cascading Effect’ May Explain Teen Violence

2008 ◽  
Vol 38 (12) ◽  
pp. 762-763
2002 ◽  
Vol 47 (5) ◽  
pp. 590-591
Author(s):  
Jackson Rainer
Keyword(s):  

Author(s):  
Brian J. Wilsey

Top predators have effects that can ‘cascade down’ on lower trophic levels. Because of this cascading effect, it matters how many trophic levels are present. Predators are either ‘sit and wait’ or ‘active’. Wolves are top predators in temperate grasslands and can alter species composition of smaller-sized predators, prey, and woody and herbaceous plant species, either through direct effects or indirect effects (‘Ecology of Fear’). In human derived grasslands, invertebrate predators fill a similar ecological role as wolves. Migrating populations of herbivores tend to be more limited by food than non-migratory populations. The phenology and synchrony of births vary among prey species in a way that is consistent with an adaptation to predation. Precocious species have highly synchronous birth dates to satiate predators. Non-precocious species (‘hiders’) have asynchronous births. Results from studies that manipulate both predators and food support the hypothesis that bottom-up and top-down effects interact.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ricardo J. Sánchez ◽  
Daniel E. Perrotti ◽  
Alejandra Gomez Paz Fort

AbstractSince 2006, when the Emma Maersk broke into the world of shipping, the growth in containership size has remained a continuous trend.For the last 14 years, since 2006, the enlargement of fullcontainerships size has remained a continuous trend since Emma Maersk broke into the world of shipping. This process - that also affected north-south trades - has crucial implications in the shipping business, particularly in the planning of ports and its services and related activities. This paper analyses the global increase in vessel size and forecasts larger vessels’ arrival to South American coasts. The paper analyses evidence since 2006 to understand the factors behind the trend for bigger ships (fleets between 18,000 and 24,000 TEU) and introduce a validated methodology for the prediction of the size of container ships. Experts presented a consensus vision in which factors associated with infrastructure, economics, technology, and the environment play a crucial role in driving the trend. Next, the paper presents a methodology for forecasting the size of containerships and applies it to Latin America’s trade. The models include two alternative thresholds for the dependent variables (1310 ft LOA and 18,000 TEU of nominal capacity) that are controlled by cascading effect (i.e., the size gap between Latin America and the world’s main trade routes), and the economic activity at the destination countries (represented by port activity). Finally, the conclusions highlight the forecast’s call to take action on infrastructure planning and investments, analyzing issues such as “economies of scale,” concentration, or entry barriers. Overall, the paper warns about the importance of efficient medium-term planning in the port industry to maximize its economic impact.


2018 ◽  
Vol 28 (1) ◽  
pp. 4-34 ◽  
Author(s):  
Maheshkumar P. Joshi ◽  
Ravi Kathuria ◽  
Sidhartha Das

This study examines a firm’s response to perceived changes in the environment, such as the growth of the digital era, at different levels of a firm—beginning with the adoption of corporate entrepreneurship (CE) down to process renewal (PR). We further explore if the technological intensity of a firm, high-tech or low-tech intensity, influences its choice of mode for organisational renewal (OR)—use of internal competence or outside acquisition—to exploit the opportunities created by the digital era. Using survey data from 170 firms, we test a sequential relationship among environmental changes (growth of the digital era), CE, OR and finally PR that involves operating procedures at the functional level. We conclude by identifying the study’s interdisciplinary contributions, which open new research avenues in the field of CE.


2021 ◽  
Author(s):  
Farhan Hafeez ◽  
Lionel Bernard ◽  
Jean-Christophe Clement ◽  
Franck Poly ◽  
Thomas Pommier

Subalpine grassland ecosystems are important from biodiversity, agriculture, and touristic perspectives but their resilience to seasonally occurring climatic extremes is increasingly challenged with climate change, accelerating their vulnerability to tipping points. Microbial communities, which are central in ecosystem functioning, are usually considered as more resistant and highly resilient to such extreme events due to their functional redundancy and strong selection in residing habitats. To investigate this, we explored the soil microbial responses upon recurrent summer droughts associated with early snowmelt in grasslands mesocosms set-up at the Lautaret Pass (French Alps). Potential respiration, nitrification and denitrification were monitored over a period of two growing seasons along with quantification of community gene abundances of total bacteria as well as (de)nitrifiers. Results revealed that droughts had a low and short-term impact on bacterial total respiration supporting their hypothesized high resistance and ability to recover. Nitrification and abundances of the corresponding functional guilds showed relatively strong resistance to summer droughts but declined in response to early snowmelt. This triggered a cascading effect on denitrification but also on the abundances of denitrifying communities which could recover from all climatic extremes except from the summer droughts where nitrifiers were collapsed. Denitrification and the respective functional groups faced high impact of applied stresses with strong reduction in the abundance and activity of this specialized community. Although, the consequently lower microbial competition for nitrate may be positive for plant biomass production, warnings exist when considering the potential nitrogen leaching from these ecosystems as well as risks of greenhouses gases emission such as N2O


2011 ◽  
Vol 73 (11-12) ◽  
pp. 1390-1397 ◽  
Author(s):  
P.S. Moya ◽  
V. Muñoz ◽  
J. Rogan ◽  
J.A. Valdivia
Keyword(s):  

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