Modelled impact of insecticide-contaminated dung on the abundance and distribution of dung fauna

2002 ◽  
Vol 92 (3) ◽  
pp. 251-263 ◽  
Author(s):  
G.A. Vale ◽  
I.F. Grant
Keyword(s):  
Population Density ◽  
Life Span ◽  
Density Dependence ◽  
Low Density ◽  
Deterministic Models ◽  
Size And Shape ◽  
Treatment Interval ◽  
Species Survival ◽  
Abundance And Distribution ◽  
The Impact

AbstractDeterministic models assessed the effects that contaminated dung from insecticide-treated cattle had on populations of three hypothetical species of dung fauna that dispersed randomly and could double their numbers every 1–28 weeks at low density. Insecticide was allowed to kill 2–98 % of adults and prevent 16–100% of breeding in pats produced immediately after cattle treatment, with toxicity declining to < 1% in pats produced 2–23 days later. Treatment intervals were 10–40 days. The modelled impact of insecticide was affected little by approximately four-fold variations in: length and density dependence of the attractive life span of pats, frequency of pat occupation by immature adults, distribution of pat toxicity during treatment interval, and changes in dispersal rates due to age and population density. Of greater importance were variations in: pat toxicity, treatment interval, frequency of pat occupation by breeding adults, density dependence of recruitment and death, natural adversity and mortality in dormancy, general rate of dispersal, and the size and shape of the area with treated cattle. Overall, it seemed that wide variations in the impact of contamination will occur in the field, but in many situations the risk to dung fauna can be substantial, especially for slow breeding beetles, and muscoids contacting insecticide on cattle. Risk extends outside the treated areas, for a distance equal to several daily displacements of the insects. Untreated refuges for species survival should be compact blocks at least 25 daily displacements wide.

scholarly journals Density dependence of developmental instability in a dimorphic ungulate

2008 ◽  
Vol 4 (5) ◽  
pp. 512-514 ◽  
Author(s):  
Emmanuel Serrano ◽  
Jean-Marc Angibault ◽  
Bruno Cargnelutti ◽  
A. J. Mark Hewison
Keyword(s):  
Population Density ◽  
Environmental Stress ◽  
Density Dependence ◽  
Fallow Deer ◽  
Individual Quality ◽  
High Population Density ◽  
Dama Dama ◽  
The Impact ◽  
Number Of Individuals ◽  
First Time

The use of fluctuating asymmetry (FA) for biomonitoring environmental stress is limited by the lack of work on how FA in particular traits responds to specific stresses. Here, by manipulating the number of individuals in an enclosed fallow deer ( Dama dama ) population, we describe, for the first time, clear density dependence in the FA of juvenile jaw morphology. The impact of high population density on FA was strong for both sexes, supporting the use of FA for indexing environmental stress. In addition, there was some indication that the change in FA was greater in males (43.6%) than females (28.5%). Finally, the ability to buffer density-dependent stress was independent of body condition. We suggest that, under highly limiting conditions, whole cohorts may be unable to buffer against developmental error, irrespective of individual quality.

scholarly journals The Impact of Health Policies and Sociodemographic Factors on Doubling Time of the COVID-19 Pandemic in Mexico

2021 ◽  
Vol 18 (5) ◽  
pp. 2354
Author(s):  
Lina Díaz-Castro ◽  
Héctor Cabello-Rangel ◽  
Kurt Hoffman
Keyword(s):  
Population Density ◽  
Doubling Time ◽  
Sociodemographic Factors ◽  
Health Policies ◽  
Government Response ◽  
University Of Oxford ◽  
Negative Effect ◽  
Population Sizes ◽  
The University ◽  
The Impact

Background. The doubling time is the best indicator of the course of the current COVID-19 pandemic. The aim of the present investigation was to determine the impact of policies and several sociodemographic factors on the COVID-19 doubling time in Mexico. Methods. A retrospective longitudinal study was carried out across March–August, 2020. Policies issued by each of the 32 Mexican states during each week of this period were classified according to the University of Oxford Coronavirus Government Response Tracker (OxCGRT), and the doubling time of COVID-19 cases was calculated. Additionally, variables such as population size and density, poverty and mobility were included. A panel data model was applied to measure the effect of these variables on doubling time. Results. States with larger population sizes issued a larger number of policies. Delay in the issuance of policies was associated with accelerated propagation. The policy index (coefficient 0.60, p < 0.01) and the income per capita (coefficient 3.36, p < 0.01) had a positive effect on doubling time; by contrast, the population density (coefficient −0.012, p < 0.05), the mobility in parks (coefficient −1.10, p < 0.01) and the residential mobility (coefficient −4.14, p < 0.01) had a negative effect. Conclusions. Health policies had an effect on slowing the pandemic’s propagation, but population density and mobility played a fundamental role. Therefore, it is necessary to implement policies that consider these variables.

scholarly journals Research on the Economic Development Threshold Effect of the Employment Density of the Shanghai Consumer Goods Industry in the Context of New Manufacturing, Based on the Experience Comparison with International Metropolis

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 969
Author(s):  
Lei Shen ◽  
Xi Zhang ◽  
Hongda Liu ◽  
Pinbo Yao
Keyword(s):  
Economic Development ◽  
Population Density ◽  
Consumer Goods ◽  
Inflection Point ◽  
Growth Potential ◽  
Positive Trend ◽  
Employment Density ◽  
Consumer Goods Industry ◽  
The Impact ◽  
Development Threshold

With the rise of a new generation of technology and industrial changes, the service-oriented manufacturing industry has become the direction of future development. With the background of new manufacturing, this paper constructs an economic development threshold model of employment density of consumer goods industry based on data from Shanghai and Tokyo from 2007 to 2016, and empirically analyzes the impact of the employment density of the consumer goods industry on urban economic development under different population densities. At the same time, by comparing the experience of Tokyo, the development status and prospects of Shanghai’s consumer goods industry are explored. The study found that the threshold of Tokyo’s consumer goods industry is 0.608. When population density is lower than this threshold, the consumer goods industry continues to promote the economic development of Tokyo; however, when the population density is higher than this threshold, the consumer goods industry begins to inhibit the economic development of Tokyo. The Shanghai consumer goods industry threshold is 0.329. Under the threshold, most of the consumer goods industry contributions to the economy are negative, but above the threshold, they begin to show a positive trend. The inflection point of the effect curve of Tokyo’s consumer goods industry on economic development has appeared, but the inflection point of Shanghai’s consumer goods industry has not yet appeared. Compared with Tokyo, the economic vitality of Shanghai’s consumer goods industry has not yet been fully released. With the continued increase of population density in Shanghai, the growth potential of the consumer goods industry is huge, and it is expected to reshape the flourishing age of Shanghai’s light industry brand.

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

scholarly journals Understanding drivers of wild oyster population persistence

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mickael Teixeira Alves ◽  
Nick G. H. Taylor ◽  
Hannah J. Tidbury
Keyword(s):  
Population Density ◽  
Carrying Capacity ◽  
Pacific Oyster ◽  
Wild Population ◽  
Population Persistence ◽  
Oyster Reefs ◽  
Oyster Population ◽  
Northern European ◽  
Age Structured ◽  
The Impact

AbstractPersistence of wild Pacific oyster, Magallana gigas, also known as Crassostrea gigas, has been increasingly reported across Northern European waters in recent years. While reproduction is inhibited by cold waters, recent warm summer temperature has increased the frequency of spawning events. Although correlation between the increasing abundance of Pacific oyster reefs in Northern European waters and climate change is documented, persistence of wild populations may also be influenced by external recruitment from farmed populations and other wild oyster populations, as well as on competition for resources with aquaculture sites. Our understanding of the combined impact of the spawning frequency, external recruitment, and competition on wild population persistence is limited. This study applied an age-structured model, based on ordinary differential equations, to describe an oyster population under discrete temperature-related dynamics. The impact of more frequent spawning events, external recruitment, and changes in carrying capacity on Pacific oyster density were simulated and compared under theoretical scenarios and two case studies in Southern England. Results indicate that long term persistence of wild oyster populations towards carrying capacity requires a high frequency of spawning events but that in the absence of spawning, external recruitment from farmed populations and other wild oyster populations may act to prevent extinction and increase population density. However, external recruitment sources may be in competition with the wild population so that external recruitment is associated with a reduction in wild population density. The implications of model results are discussed in the context of wild oyster population management.

scholarly journals Risk factors for physical inactivity across the adult life span: the impact of depression

2006 ◽  
Vol 18 (6) ◽  
pp. 274-274
Author(s):  
J Walker ◽  
H Christensen ◽  
T Windsor ◽  
A George
Keyword(s):  
Risk Factors ◽  
Life Span ◽  
Physical Inactivity ◽  
Adult Life ◽  
Adult Life Span ◽  
The Impact

Density dependence of the Hanle effect of the 3s4p1P10 level of neutral magnesium

1979 ◽  
Vol 57 (6) ◽  
pp. 838-840
Author(s):  
F. M. Kelly ◽  
M. S. Mathur
Keyword(s):  
Density Dependence ◽  
Excited Level ◽  
Lifetime Measurement ◽  
Oscillator Strengths ◽  
Low Density ◽  
Hanle Effect

The Hanle effect in the 3s2 1S0–3s4p1P1 (2026 Å) transition of Mg I has been studied over a range of densities. The low density observations lead to an accurate lifetime measurement of the 4p1P1 excited level. Related oscillator strengths are calculated.

The Impact of Invisible Illness on Identity and Contextual Age Across the Life Span

2003 ◽  
Vol 15 (3) ◽  
pp. 331-347 ◽  
Author(s):  
Amanda L. Kundrat ◽  
Jon F. Nussbaum
Keyword(s):  
Life Span ◽  
The Impact
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