scholarly journals COVID-19 Cases and Deaths: A Comparison among Bangladesh, India and Pakistan

2021 ◽  
Vol 3 (5) ◽  
pp. 01-06
Author(s):  
B. M. Kibria
Keyword(s):  
Population Sizes ◽  
The Impact

This paper compares the number of infected cases and deaths of an ongoing pandemic of COVID-19 outbreak for Bangladesh, India and Pakistan for the period of March 8, 2020 to September 21, 2020. Comparisons among countries using absolute numbers are not comparable due to different factors, such as population sizes, rates of per 100,000 and also because not all countries are affected equally and at the same time. Following Middelburg and Rosendaal (2020), we graphically compare the number of cases and deaths expressed as a percentage of the cases and deaths on the reference day 25 after the first reported death. To see the impact of reference days, several later reference days are also considered in this study. From these comparisons, clear differences were observed among countries. Among these three countries, it is observed that Bangladesh had the most extreme flattening of the curve, followed by Pakistan and then India. We observed that the epidemic developed in India much more rapidly as compare to Bangladesh and Pakistan.

Characterizing the impact of recovering sea otters on commercially important crabs in California estuaries

2020 ◽  
Vol 655 ◽  
pp. 123-137
Author(s):  
TM Grimes ◽  
MT Tinker ◽  
BB Hughes ◽  
KE Boyer ◽  
L Needles ◽  
...  
Keyword(s):  
Abiotic Factors ◽  
Sea Otter ◽  
Dungeness Crab ◽  
Sea Otters ◽  
Elkhorn Slough ◽  
Enhydra Lutris Nereis ◽  
Crab Abundance ◽  
Population Sizes ◽  
Commercially Important ◽  
The Impact

Protective legislation and management have led to an increase in California’s sea otter Enhydra lutris nereis population. While sea otter recovery has been linked to ecosystem benefits, sea otter predation may negatively affect commercially valuable species. Understanding the potential influence of sea otters is of particular importance as their range expands into estuaries that function as nurseries for commercially valuable species like Dungeness crab Metacarcinus magister. We consider how sea otter predation has affected the abundance and size of juvenile Dungeness crab in Elkhorn Slough, California, USA, and analyzed cancrid crab abundance and size across 4 California estuaries with and without sea otters to understand how biotic and abiotic factors contribute to observed variation in crab size and abundance. We compared trends in southern sea otters relative to Dungeness crab landings in California to assess whether increasing sea otter abundance have negatively impacted landings. In Elkhorn Slough, juvenile Dungeness crab abundance and size have declined since 2012, coinciding with sea otter population growth. However, the impact of sea otters on juvenile Dungeness crab size was habitat-specific and only significant in unvegetated habitat. Across estuaries, we found that cancrid crab abundance and size were negatively associated with sea otter presence. While abiotic factors varied among estuaries, these factors explained little of the observed variation in crab abundance or size. Although we found evidence that sea otters can have localized effects on cancrid crab populations within estuaries, we found no evidence that southern sea otters, at recent population sizes, have negatively impacted Dungeness crab landings in California from 2000-2014.

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 The impact of large terrestrial carnivores on Pleistocene ecosystems

2015 ◽  
Vol 113 (4) ◽  
pp. 862-867 ◽  
Author(s):  
Blaire Van Valkenburgh ◽  
Matthew W. Hayward ◽  
William J. Ripple ◽  
Carlo Meloro ◽  
V. Louise Roth
Keyword(s):  
Prey Size ◽  
Habitat Degradation ◽  
Terrestrial Ecosystems ◽  
Growth Data ◽  
Predator Prey ◽  
Body Sizes ◽  
Population Sizes ◽  
Potential Impact ◽  
The Impact ◽  
Ground Sloths

Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.

scholarly journals On mechanisms of trophic cascade caused by anti-predation response in food chain systems

2020 ◽  
Vol 1 (2) ◽  
pp. 1-27
Author(s):  
Yang Wang ◽  
Xingfu Zou
Keyword(s):  
Food Chain ◽  
Trophic Cascade ◽  
Predation Rate ◽  
Model Systems ◽  
Large Carnivores ◽  
Response Level ◽  
Population Sizes ◽  
The Cost ◽  
The Impact ◽  
D Model

Motivated by a recent field study [Nat. Commun. 7(2016), 10698] on the impact of fear of large carnivores on the populations in a cascading ecosystem of food chain type with the large carnivores as the top predator, in this paper we propose two model systems in the form of ordinary differential equations to mechanistically explore the cascade of such a fear effect. The models are of the Lotka-Volterra type, one is three imensional and the other four dimensional. The 3-D model only considers the cost of the anti-predation response reflected in the decrease of the production, while the 4-D model considers also the benefit of the response in reducing the predation rate, in addition to the cost by reducing the production. We perform a thorough analysis on the dynamics of the two models. The results reveal that the 3-D model and 4-model demonstrate opposite patterns for trophic cascade in terms of the dependence of population sizes for each species at the co-existence equilibrium on the anti-predation response level parameter, and such a difference is attributed to whether or not there is a benefit for the anti-predation response by the meso-carnivore species.

scholarly journals Incorporating genetic selection into individual-based models (IBMs) of malaria and other infectious diseases

2019 ◽  
Author(s):  
Ian M. Hastings ◽  
Raman Sharma
Keyword(s):  
Control Strategies ◽  
Genetic Parameter ◽  
Genetic Selection ◽  
Wait Time ◽  
Antimicrobial Drug Resistance ◽  
Infinite Population ◽  
Individual Based Models ◽  
Population Sizes ◽  
Human Infections ◽  
The Impact

AbstractOptimal control strategies for human infections are often investigated by computational approaches using individual-based models (IBMs). These typically track humans and evaluate the impact of control interventions in terms of human deaths, clinical cases averted, interruption of transmission etc. Genetic selection can be incorporated into these IBMs and used to track the spread of mutations whose origin and spread are often driven by the intervention, and which subsequently undermine the control strategy; for example, mutations which encode antimicrobial drug resistance or diagnosis- or vaccine-escape phenotypes. Basic population genetic descriptions of selection are based on infinite population sizes (so that chance fluctuations in allele frequency are absent) but IBMs track finite population sizes. We describe how the finite sizes of IBMs affect simulating the dynamics of genetic selection and how best to incorporate genetic selection into these models. We use the OpenMalaria IBM of malaria as an example, but the same principles apply to IBMs of other diseases. We identify four strategies to incorporate selection into IBMs and make the following four recommendations. Firstly, calculate and report the selection coefficients, s, of the advantageous allele as the key genetic parameter. Secondly, use these values of ‘s’ to calculate the wait-time until a mutation successful establishes itself in the population. The wait time for the mutation can be added to speed of selection, s, to calculate when the mutation will reach significant, operationally important levels. Thirdly, quantify the ability of the IBM to robustly estimate small selection coefficients. Fourthly, optimise computational efficacy: when ‘s’ is small it is plausible that fewer replicates of larger IBMs will be more efficient than a larger number of replicates of smaller size.

scholarly journals The Impact of High-Speed Railways on Unequal Accessibility Based on Ticket Prices in Korea

2020 ◽  
Vol 12 (16) ◽  
pp. 6302
Author(s):  
Kyungtaek Kim ◽  
Junghoon Kim
Keyword(s):  
Urban Population ◽  
High Speed ◽  
National Level ◽  
High Speed Railway ◽  
Large Cities ◽  
South Korean ◽  
Time Value ◽  
Population Sizes ◽  
Ticket Prices ◽  
The Impact

The high-speed railway (HSR) has affected accessibility at diverse spatial levels. Although previous studies have examined HSR impacts on accessibility and inequality, the price attribute in estimating accessibility is less noted. This study evaluates the effects of HSR on unequal accessibility at the South Korean national level, capital and non-capital regions and according to urban population sizes by comparing ticket prices to time values. There are two major conclusions of this study. First, an increase in time value through national growth or other exogenous conditions maximizes HSR impact and, thus, increases accessibility. For example, when the time value is 9.98 USD/h, the national HSR access inequality is reduced by 0.56%. However, when the time value is 6.02 USD/h, the reduction in the national inequality by the HSR is 0.19%. Second, if considering generalized travel time, HSR impact is maximized in medium cities rather than in large cities. When the time value is 6.02 USD/h (or 9.98 USD/h), the change in inequality between cities is −0.4% (−1.29%) in medium cities, while large cities show a −0.08% (−0.9%) reduction in access inequality.

Ethics of Primate Fieldwork: Toward an Ethically Engaged Primatology

2018 ◽  
Vol 47 (1) ◽  
pp. 493-512 ◽  
Author(s):  
Erin P. Riley ◽  
Michelle Bezanson
Keyword(s):  
Best Practices ◽  
Field Research ◽  
Anthropogenic Factors ◽  
Ethical Practice ◽  
Theoretical Frameworks ◽  
Population Sizes ◽  
History Of ◽  
The Impact ◽  
Term Field

Field primatologists have ethical responsibilities that extend beyond study subjects to the local human communities living near primate populations and their surrounding ecosystems. In this review, we explore the history of ethical discussions within anthropological primatology and examine the best practices for an ethically engaged primatology that should be followed and role-modeled by primatologists. An increasing number of primates are showing reduced population sizes and are in imminent danger of extinction; thus, we need to carefully consider the ethics of intervening to ensure the survival of remaining populations, the impact of anthropogenic factors (e.g., climate change), and whether long-term field research results in conservation outcomes that consider local human communities. Because best practices change over time as theoretical frameworks and methodological tools advance and scientific goals change, field primatologists must continually reflect on what constitutes ethical practice and consider how research influences the overlapping dimensions of fieldwork: primates, people, and ecosystems.

scholarly journals Evolution of the sheep coat: the impact of domestication on its structure and development

2020 ◽  
Vol 102 ◽  
Author(s):  
Neville Jackson ◽  
Ian G. Maddocks ◽  
James E. Watts ◽  
David Scobie ◽  
Rebecca S. Mason ◽  
...  
Keyword(s):  
Bronze Age ◽  
Notch Pathway ◽  
Embryonic Cell ◽  
Specific Cell ◽  
Genetic Changes ◽  
Sheep Population ◽  
Continuous Growth ◽  
In The Wild ◽  
Population Sizes ◽  
The Impact

Abstract Wild sheep and many primitive domesticated breeds have two coats: coarse hairs covering shorter, finer fibres. Both are shed annually. Exploitation of wool for apparel in the Bronze Age encouraged breeding for denser fleeces and continuously growing white fibres. The Merino is regarded as the culmination of this process. Archaeological discoveries, ancient images and parchment records portray this as an evolutionary progression, spanning millennia. However, examination of the fleeces from feral, two-coated and woolled sheep has revealed a ready facility of the follicle population to change from shedding to continuous growth and to revert from domesticated to primitive states. Modifications to coat structure, colour and composition have occurred in timeframes and to sheep population sizes that exclude the likelihood of variations arising from mutations and natural selection. The features are characteristic of the domestication phenotype: an assemblage of developmental, physiological, skeletal and hormonal modifications common to a wide variety of species under human control. The phenotypic similarities appeared to result from an accumulation of cryptic genetic changes early during vertebrate evolution. Because they did not affect fitness in the wild, the mutations were protected from adverse selection, becoming apparent only after exposure to a domestic environment. The neural crest, a transient embryonic cell population unique to vertebrates, has been implicated in the manifestations of the domesticated phenotype. This hypothesis is discussed with reference to the development of the wool follicle population and the particular roles of Notch pathway genes, culminating in the specific cell interactions that typify follicle initiation.

scholarly journals Early estimates of COVID-19 infections in small, medium and large population clusters

2020 ◽  
Vol 5 (9) ◽  
pp. e003055
Author(s):  
Amir Siraj ◽  
Alemayehu Worku ◽  
Kiros Berhane ◽  
Maru Aregawi ◽  
Munir Eshetu ◽  
...  
Keyword(s):  
Large Population ◽  
Face Mask ◽  
Sub Saharan Africa ◽  
Contact Tracing ◽  
Local Context ◽  
African Region ◽  
Social Distancing ◽  
Population Sizes ◽  
Sub Saharan ◽  
The Impact

IntroductionSince its emergence in late December 2019, COVID-19 has rapidly developed into a pandemic in mid of March with many countries suffering heavy human loss and declaring emergency conditions to contain its spread. The impact of the disease, while it has been relatively low in the sub-Saharan Africa (SSA) as of May 2020, is feared to be potentially devastating given the less developed and fragmented healthcare system in the continent. In addition, most emergency measures practised may not be effective due to their limited affordability as well as the communal way people in SSA live in relative isolation in clusters of large as well as smaller population centres.MethodsTo address the acute need for estimates of the potential impacts of the disease once it sweeps through the African region, we developed a process-based model with key parameters obtained from recent studies, taking local context into consideration. We further used the model to estimate the number of infections within a year of sustained local transmissions under scenarios that cover different population sizes, urban status, effectiveness and coverage of social distancing, contact tracing and usage of cloth face mask.ResultsWe showed that when implemented early, 50% coverage of contact tracing and face mask, with 33% effective social distancing policies can bringing the epidemic to a manageable level for all population sizes and settings we assessed. Relaxing of social distancing in urban settings from 33% to 25% could be matched by introduction and maintenance of face mask use at 43%.ConclusionsIn SSA countries with limited healthcare workforce, hospital resources and intensive care units, a robust system of social distancing, contact tracing and face mask use could yield in outcomes that prevent several millions of infections and thousands of deaths across the continent.

The Impact of Acanthaster on Corals and Coral Reefs in the Eastern Pacific

1974 ◽  
Vol 1 (4) ◽  
pp. 295-304 ◽  
Author(s):  
Peter W. Glynn
Keyword(s):  
Species Diversity ◽  
Field Work ◽  
Coral Community ◽  
Eastern Pacific ◽  
Live Coral ◽  
Sea Star ◽  
Coral Communities ◽  
Negative Effect ◽  
Population Sizes ◽  
The Impact

The movement of surface currents and the availability of coral prey are probably not responsible for the discontinuities in the distribution of Acanthaster (the Crown-of-thorns Starfish or Sea-star) in American waters. Temperature and salinity conditions are critical in development, and it is possible that these parameters are effective locally, for example in the Gulf of Panamá. There is a strong possibility that continuing field work will show that Acanthaster has a significantly more widespread distribution in the eastern Pacific than is currently known.Adult Acanthaster and several species of coral prey exhibited an unusually high tolerance to varying conditions of temperature and salinity. The possibility of step-wise colonization to new areas, mediated by resistant adult populations that can become established during favourable seasons, should be considered in any plans to alter the existing freshwater canal in Panamá. For introductions can be environmentally dangerous.The highest population densities of Acanthaster so far observed in the eastern Pacific, 1 individual/40 m2 to approximately 1 individual/100 m2, are comparable to population sizes in the Indo-Pacific region that are not considered to have a serious impact on coral communities. Coral destruction by Acanthaster can be significant in certain limited areas, but is usually less than that caused by other corallivores.An analysis of coral community structure in relation to Acanthaster density failed to show a significant correlation with (a) number of species, (b) number of live coral colonies, (c) species diversity (H'), or (d) species evenness (J').Prey preference data indicate that Acanthaster selectively destroys rare corals. Replacement of rare, predated corals by fast-growing species (Pocillopora spp.) has been observed in the field, showing that Acanthaster could have a negative effect on species diversity.

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