Forest tent caterpillar, Malacosoma disstria (Lepidoptera: Lasiocampidae mate-finding behavior is greatest at intermediate population densities: Implications for interpretation of moth capture in pheromone-baited traps.

Directory of Open Access Journals (Sweden)

Maya L. Evenden

2015-07-01

Full Text Available The forest tent caterpillar, Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae is a native forest defoliator with a broad geographic range in North America. Forest tent caterpillars experience cyclical population changes and at high densities, repeated defoliation can cause reduced tree growth and tree mortality. Pheromone-based monitoring of forest tent caterpillar moths can provide information on spatial and temporal patterns of incipient outbreaks. Pheromone-baited trap capture of male moths correlates to the number of eggs and pupae in a population but this relationship breaks down at high population densities, when moth trap capture declines. The objective of the current study is to understand the mechanisms that reduce trap capture at high population densities. We tested two different hypotheses: 1 at high population densities, male moth orientation to pheromone sources is reduced due to competition for pheromone plumes; and 2 moths from high density populations will be in poor condition and less likely to conduct mate-finding behaviors than moths from low density populations. A field study showed non-linear effects of density on male moth capture in female-baited traps. The number of males captured increased up to an intermediate density level and declined at the highest densities. Field cage studies showed that female moth density affected male moth orientation to female-baited traps, as more males were recaptured at low than high female densities. There was no effect of male density on the proportion of males that oriented to female-baited traps. Moth condition was manipulated by varying larval food quantity. Although feeding regimes affected the moth condition (size, there was no evidence of an effect of condition on mate finding or close range mating behavior. In the field, it is likely that competition for pheromone plumes at high female densities during population outbreaks reduces the efficacy of pheromone-baited monitoring

10 CFR 960.5-2-1 - Population density and distribution.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Population density and distribution. 960.5-2-1 Section 960... Population density and distribution. (a) Qualifying condition. The site shall be located such that, during... specified in § 960.5-1(a)(1). (b) Favorable conditions. (1) A low population density in the general region...

Density-dependent feedbacks can mask environmental drivers of populations

DEFF Research Database (Denmark)

Dahlgren, Johan Petter

I present some results from studies identifying environmental drivers of vital rates and population dynamics when controlling for intraspecific density statistically or experimentally, show that density dependence can be strong even in populations of slow-growing species in stressful habitats, an...

Energetic and ecological constraints on population density of reef fishes.

Science.gov (United States)

Barneche, D R; Kulbicki, M; Floeter, S R; Friedlander, A M; Allen, A P

2016-01-27

Population ecology has classically focused on pairwise species interactions, hindering the description of general patterns and processes of population abundance at large spatial scales. Here we use the metabolic theory of ecology as a framework to formulate and test a model that yields predictions linking population density to the physiological constraints of body size and temperature on individual metabolism, and the ecological constraints of trophic structure and species richness on energy partitioning among species. Our model was tested by applying Bayesian quantile regression to a comprehensive reef-fish community database, from which we extracted density data for 5609 populations spread across 49 sites around the world. Our results indicate that population density declines markedly with increases in community species richness and that, after accounting for richness, energetic constraints are manifested most strongly for the most abundant species, which generally are of small body size and occupy lower trophic groups. Overall, our findings suggest that, at the global scale, factors associated with community species richness are the major drivers of variation in population density. Given that populations of species-rich tropical systems exhibit markedly lower maximum densities, they may be particularly susceptible to stochastic extinction. © 2016 The Author(s).

Non-invasive genetic censusing and monitoring of primate populations.

Science.gov (United States)

Arandjelovic, Mimi; Vigilant, Linda

2018-03-01

Knowing the density or abundance of primate populations is essential for their conservation management and contextualizing socio-demographic and behavioral observations. When direct counts of animals are not possible, genetic analysis of non-invasive samples collected from wildlife populations allows estimates of population size with higher accuracy and precision than is possible using indirect signs. Furthermore, in contrast to traditional indirect survey methods, prolonged or periodic genetic sampling across months or years enables inference of group membership, movement, dynamics, and some kin relationships. Data may also be used to estimate sex ratios, sex differences in dispersal distances, and detect gene flow among locations. Recent advances in capture-recapture models have further improved the precision of population estimates derived from non-invasive samples. Simulations using these methods have shown that the confidence interval of point estimates includes the true population size when assumptions of the models are met, and therefore this range of population size minima and maxima should be emphasized in population monitoring studies. Innovations such as the use of sniffer dogs or anti-poaching patrols for sample collection are important to ensure adequate sampling, and the expected development of efficient and cost-effective genotyping by sequencing methods for DNAs derived from non-invasive samples will automate and speed analyses. © 2018 Wiley Periodicals, Inc.

Proteomic Markers of Functional Sperm Population in Bovines: Comparison of Low- and High-Density Spermatozoa Following Cryopreservation.

Science.gov (United States)

D'Amours, Olivier; Frenette, Gilles; Bourassa, Sylvie; Calvo, Ézéchiel; Blondin, Patrick; Sullivan, Robert

2018-01-05

Mammalian semen contains a heterogeneous population of sperm cells. This heterogeneity results from variability in the complex processes of cell differentiation in the testis, biochemical modifications undergone by spermatozoa during transit along the male reproductive tract, interactions with secretions from accessory sex glands at ejaculation, and, in the context of reproductive technologies, in the ability of ejaculated spermatozoa to resist damage associated with freeze-thaw procedures. When submitted to density gradient centrifugation, ejaculated spermatozoa distribute themselves into two distinct populations: a low-density population characterized by low motility parameters, and a high-density population with high motility characteristics. To understand the origin of ejaculated spermatozoa heterogeneity, cryopreserved semen samples from bulls used by the artificial insemination (A.I.) industry were submitted to Percoll gradient centrifugation. Proteins from low and high density spermatozoa were then extracted with sodium deoxycholate and submitted to proteomic analysis using iTRAQ (isobaric tag for relative and absolute quantitation) methodologies. Quantification of selected sperm proteins was confirmed by multiple reaction monitoring (MRM). Overall, 31 different proteins were more abundant in low-density spermatozoa, while 80 different proteins were more abundant in the high-density subpopulation. Proteins enriched in high-density spermatozoa were markers of sperm functionality such as the glycolytic process, binding to the egg zona pellucida, and motility. Low-density spermatozoa were not solely characterized by loss of proteins and their associated functions. Chaperonin-containing TCP1s and chaperones are hallmarks of the low-density subpopulation. iTRAQ analysis revealed that other proteins such as binder of sperm proteins, histone, GPX5, ELSPBP1, and clusterin are overexpressed in low-density spermatozoa suggesting that these proteins represent defects

Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

Directory of Open Access Journals (Sweden)

Steffen Oppel

2014-04-01

Full Text Available Population size assessments for nocturnal burrow-nesting seabirds are logistically challenging because these species are active in colonies only during darkness and often nest on remote islands where manual inspections of breeding burrows are not feasible. Many seabird species are highly vocal, and recent technological innovations now make it possible to record and quantify vocal activity in seabird colonies. Here we test the hypothesis that remotely recorded vocal activity in Cory’s shearwater (Calonectris borealis breeding colonies in the North Atlantic increases with nest density, and combined this relationship with cliff habitat mapping to estimate the population size of Cory’s shearwaters on the island of Corvo (Azores. We deployed acoustic recording devices in 9 Cory’s shearwater colonies of known size to establish a relationship between vocal activity and local nest density (slope = 1.07, R2 = 0.86, p < 0.001. We used this relationship to predict the nest density in various cliff habitat types and produced a habitat map of breeding cliffs to extrapolate nest density around the island of Corvo. The mean predicted nest density on Corvo ranged from 6.6 (2.1–16.2 to 27.8 (19.5–36.4 nests/ha. Extrapolation of habitat-specific nest densities across the cliff area of Corvo resulted in an estimate of 6326 Cory’s shearwater nests (95% confidence interval: 3735–10,524. This population size estimate is similar to previous assessments, but is too imprecise to detect moderate changes in population size over time. While estimating absolute population size from acoustic recordings may not be sufficiently precise, the strong positive relationship that we found between local nest density and recorded calling rate indicates that passive acoustic monitoring may be useful to document relative changes in seabird populations over time.

Using non-invasively collected genetic data to estimate density and population size of tigers in the Bangladesh Sundarbans

Directory of Open Access Journals (Sweden)

M. Abdul Aziz

2017-10-01

Full Text Available Population density is a key parameter to monitor endangered carnivores in the wild. The photographic capture-recapture method has been widely used for decades to monitor tigers, Panthera tigris, however the application of this method in the Sundarbans tiger landscape is challenging due to logistical difficulties. Therefore, we carried out molecular analyses of DNA contained in non-invasively collected genetic samples to assess the tiger population in the Bangladesh Sundarbans within a spatially explicit capture-recapture (SECR framework. By surveying four representative sample areas totalling 1994 km2 of the Bangladesh Sundarbans, we collected 440 suspected tiger scat and hair samples. Genetic screening of these samples provided 233 authenticated tiger samples, which we attempted to amplify at 10 highly polymorphic microsatellite loci. Of these, 105 samples were successfully amplified, representing 45 unique genotype profiles. The capture-recapture analyses of these unique genotypes within the SECR model provided a density estimate of 2.85 ± SE 0.44 tigers/100 km2 (95% CI: 1.99–3.71 tigers/100 km2 for the area sampled, and an estimate of 121 tigers (95% CI: 84–158 tigers for the total area of the Bangladesh Sundarbans. We demonstrate that this non-invasive genetic surveillance can be an additional approach for monitoring tiger populations in a landscape where camera-trapping is challenging.

Evaluation and comparison of high population density sites

International Nuclear Information System (INIS)

Margulies, T.S.

1979-10-01

Consideration of the population distribution surrounding a potential nuclear site generally includes the calculation of population density over a circular area outward to a radial distance of 30 miles from the site. A recently proposed nuclear site Perryman, Maryland challenged the NRC population density guidelines and motivated this project which was performed under the Maryland Power Plant Siting Program. The report provides a comparison of several site population factor indices for comparing relative public safety aspects of alternative nuclear power plant sites. In addition, it is illustrated that use of the reactor safety study (WASH-1400) consequence model as a tool for comparing the relative safety of alternative sites has potential pitfalls

Estimating the population density of the Asian tapir (Tapirus indicus) in a selectively logged forest in Peninsular Malaysia.

Science.gov (United States)

Rayan, D Mark; Mohamad, Shariff Wan; Dorward, Leejiah; Aziz, Sheema Abdul; Clements, Gopalasamy Reuben; Christopher, Wong Chai Thiam; Traeholt, Carl; Magintan, David

2012-12-01

The endangered Asian tapir (Tapirus indicus) is threatened by large-scale habitat loss, forest fragmentation and increased hunting pressure. Conservation planning for this species, however, is hampered by a severe paucity of information on its ecology and population status. We present the first Asian tapir population density estimate from a camera trapping study targeting tigers in a selectively logged forest within Peninsular Malaysia using a spatially explicit capture-recapture maximum likelihood based framework. With a trap effort of 2496 nights, 17 individuals were identified corresponding to a density (standard error) estimate of 9.49 (2.55) adult tapirs/100 km(2) . Although our results include several caveats, we believe that our density estimate still serves as an important baseline to facilitate the monitoring of tapir population trends in Peninsular Malaysia. Our study also highlights the potential of extracting vital ecological and population information for other cryptic individually identifiable animals from tiger-centric studies, especially with the use of a spatially explicit capture-recapture maximum likelihood based framework. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

Influences of population size and density on birthplace effects.

Science.gov (United States)

Hancock, David J; Coutinho, Patrícia; Côté, Jean; Mesquita, Isabel

2018-01-01

Contextual influences on talent development (e.g., birthplace effects) have become a topic of interest for sport scientists. Birthplace effects occur when being born in a certain city size leads to participation or performance advantages, typically for those born in smaller or mid-sized cities. The purpose of this study was to investigate birthplace effects in Portuguese volleyball players by analysing city size, as well as population density - an important but infrequently used variable. Participants included 4062 volleyball players (M age  = 33), 53.2% of whom were men. Using Portuguese national census data from 1981, we compared participants (within each sex) across five population categories. In addition, we used ANOVAs to study expertise and population density. Results indicated that men and women athletes born in districts of 200,000-399,999 were 2.4 times more likely to attain elite volleyball status, while all other districts decreased the odds of expert development. For men, being born in high-density areas resulted in less chance of achieving expertise, whereas there were no differences for women. The results suggest that athletes' infrastructure and social structure play an important role in talent development, and that these structures are influenced by total population and population density, respectively.

The influence of population density and duration of breeding on ...

African Journals Online (AJOL)

USER

2010-07-12

Jul 12, 2010 ... profitability could be more advantageous if the increased population density goes up to 16 birds per m2; or the ... addition, increased population density of broiler chickens reduces the body weight .... and labor costs. The main ...

Demographic monitoring of wild muriqui populations: Criteria for defining priority areas and monitoring intensity.

Science.gov (United States)

Strier, Karen B; Possamai, Carla B; Tabacow, Fernanda P; Pissinatti, Alcides; Lanna, Andre M; Rodrigues de Melo, Fabiano; Moreira, Leandro; Talebi, Maurício; Breves, Paula; Mendes, Sérgio L; Jerusalinsky, Leandro

2017-01-01

Demographic data are essential to assessments of the status of endangered species. However, establishing an integrated monitoring program to obtain useful data on contemporary and future population trends requires both the identification of priority areas and populations and realistic evaluations of the kinds of data that can be obtained under different monitoring regimes. We analyzed all known populations of a critically endangered primate, the muriqui (genus: Brachyteles) using population size, genetic uniqueness, geographic importance (including potential importance in corridor programs) and implementability scores to define monitoring priorities. Our analyses revealed nine priority populations for the northern muriqui (B. hypoxanthus) and nine for the southern muriqui (B. arachnoides). In addition, we employed knowledge of muriqui developmental and life history characteristics to define the minimum monitoring intensity needed to evaluate demographic trends along a continuum ranging from simple descriptive changes in population size to predictions of population changes derived from individual based life histories. Our study, stimulated by the Brazilian government's National Action Plan for the Conservation of Muriquis, is fundamental to meeting the conservation goals for this genus, and also provides a model for defining priorities and methods for the implementation of integrated demographic monitoring programs for other endangered and critically endangered species of primates.

Demographic monitoring of wild muriqui populations: Criteria for defining priority areas and monitoring intensity.

Directory of Open Access Journals (Sweden)

Karen B Strier

Full Text Available Demographic data are essential to assessments of the status of endangered species. However, establishing an integrated monitoring program to obtain useful data on contemporary and future population trends requires both the identification of priority areas and populations and realistic evaluations of the kinds of data that can be obtained under different monitoring regimes. We analyzed all known populations of a critically endangered primate, the muriqui (genus: Brachyteles using population size, genetic uniqueness, geographic importance (including potential importance in corridor programs and implementability scores to define monitoring priorities. Our analyses revealed nine priority populations for the northern muriqui (B. hypoxanthus and nine for the southern muriqui (B. arachnoides. In addition, we employed knowledge of muriqui developmental and life history characteristics to define the minimum monitoring intensity needed to evaluate demographic trends along a continuum ranging from simple descriptive changes in population size to predictions of population changes derived from individual based life histories. Our study, stimulated by the Brazilian government's National Action Plan for the Conservation of Muriquis, is fundamental to meeting the conservation goals for this genus, and also provides a model for defining priorities and methods for the implementation of integrated demographic monitoring programs for other endangered and critically endangered species of primates.

Density dependence in a recovering osprey population: demographic and behavioural processes.

Science.gov (United States)

Bretagnolle, V; Mougeot, F; Thibault, J-C

2008-09-01

1. Understanding how density-dependent and independent processes influence demographic parameters, and hence regulate population size, is fundamental within population ecology. We investigated density dependence in growth rate and fecundity in a recovering population of a semicolonial raptor, the osprey Pandion haliaetus [Linnaeus, 1758], using 31 years of count and demographic data in Corsica. 2. The study population increased from three pairs in 1974 to an average of 22 pairs in the late 1990s, with two distinct phases during the recovery (increase followed by stability) and contrasted trends in breeding parameters in each phase. 3. We show density dependence in population growth rate in the second phase, indicating that the stabilized population was regulated. We also show density dependence in productivity (fledging success between years and hatching success within years). 4. Using long-term data on behavioural interactions at nest sites, and on diet and fish provisioning rate, we evaluated two possible mechanisms of density dependence in productivity, food depletion and behavioural interference. 5. As density increased, both provisioning rate and the size of prey increased, contrary to predictions of a food-depletion mechanism. In the time series, a reduction in fledging success coincided with an increase in the number of non-breeders. Hatching success decreased with increasing local density and frequency of interactions with conspecifics, suggesting that behavioural interference was influencing hatching success. 6. Our study shows that, taking into account the role of non-breeders, in particular in species or populations where there are many floaters and where competition for nest sites is intense, can improve our understanding of density-dependent processes and help conservation actions.

Scaling laws between population and facility densities.

Science.gov (United States)

Um, Jaegon; Son, Seung-Woo; Lee, Sung-Ik; Jeong, Hawoong; Kim, Beom Jun

2009-08-25

When a new facility like a grocery store, a school, or a fire station is planned, its location should ideally be determined by the necessities of people who live nearby. Empirically, it has been found that there exists a positive correlation between facility and population densities. In the present work, we investigate the ideal relation between the population and the facility densities within the framework of an economic mechanism governing microdynamics. In previous studies based on the global optimization of facility positions in minimizing the overall travel distance between people and facilities, it was shown that the density of facility D and that of population rho should follow a simple power law D approximately rho(2/3). In our empirical analysis, on the other hand, the power-law exponent alpha in D approximately rho(alpha) is not a fixed value but spreads in a broad range depending on facility types. To explain this discrepancy in alpha, we propose a model based on economic mechanisms that mimic the competitive balance between the profit of the facilities and the social opportunity cost for populations. Through our simple, microscopically driven model, we show that commercial facilities driven by the profit of the facilities have alpha = 1, whereas public facilities driven by the social opportunity cost have alpha = 2/3. We simulate this model to find the optimal positions of facilities on a real U.S. map and show that the results are consistent with the empirical data.

The effect of different initial densities of nematode (Meloidogyne javanica) on the build-up of Pasteuria penetrans population.

Science.gov (United States)

Darban, Daim Ali; Pathan, Mumtaz Ali; Bhatti, Abdul Ghaffar; Maitelo, Sultan Ahmed

2005-02-01

Pasteuria penetrans will build-up faster where there is a high initial nematode density and can suppress root-knot nematode populations in the roots of tomato plants. The effect of different initial densities of nematode (Meloidogyne javanica) (150, 750, 1500, 3000) and P. penetrans infected females (F1, F3) densities (F0=control and AC=absolute control without nematode or P. penetrans inoculum) on the build-up of Pasteuria population was investigated over four crop cycles. Two major points of interest were highlighted. First, that within a confined soil volume, densities of P. penetrans can increase >100 times within 2 or 3 crop cycles. Second, from a relatively small amount of spore inoculum, infection of the host is very high. There were more infected females in the higher P. penetrans doses. The root growth data confirms the greater number of females in the controls particularly at the higher inoculum densities in the third and fourth crops. P. penetrans generally caused the fresh root weights to be higher than those in the control. P. penetrans has shown greater reduction of egg masses per plant at most densities. The effects of different initial densities of M. javanica and P. penetrans on the development of the pest and parasite populations were monitored. And no attempt was made to return the P. penetrans spores to the pots after each crop so the build-up in actual numbers of infected females and spores under natural conditions may be underestimated.

Effective size of density-dependent two-sex populations: the effect of mating systems.

Science.gov (United States)

Myhre, A M; Engen, S; SAEther, B-E

2017-08-01

Density dependence in vital rates is a key feature affecting temporal fluctuations of natural populations. This has important implications for the rate of random genetic drift. Mating systems also greatly affect effective population sizes, but knowledge of how mating system and density regulation interact to affect random genetic drift is poor. Using theoretical models and simulations, we compare N e in short-lived, density-dependent animal populations with different mating systems. We study the impact of a fluctuating, density-dependent sex ratio and consider both a stable and a fluctuating environment. We find a negative relationship between annual N e /N and adult population size N due to density dependence, suggesting that loss of genetic variation is reduced at small densities. The magnitude of this decrease was affected by mating system and life history. A male-biased, density-dependent sex ratio reduces the rate of genetic drift compared to an equal, density-independent sex ratio, but a stochastic change towards male bias reduces the N e /N ratio. Environmental stochasticity amplifies temporal fluctuations in population size and is thus vital to consider in estimation of effective population sizes over longer time periods. Our results on the reduced loss of genetic variation at small densities, particularly in polygamous populations, indicate that density regulation may facilitate adaptive evolution at small population sizes. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Passive acoustic monitoring of beaked whale densities in the Gulf of Mexico.

Science.gov (United States)

Hildebrand, John A; Baumann-Pickering, Simone; Frasier, Kaitlin E; Trickey, Jennifer S; Merkens, Karlina P; Wiggins, Sean M; McDonald, Mark A; Garrison, Lance P; Harris, Danielle; Marques, Tiago A; Thomas, Len

2015-11-12

Beaked whales are deep diving elusive animals, difficult to census with conventional visual surveys. Methods are presented for the density estimation of beaked whales, using passive acoustic monitoring data collected at sites in the Gulf of Mexico (GOM) from the period during and following the Deepwater Horizon oil spill (2010-2013). Beaked whale species detected include: Gervais' (Mesoplodon europaeus), Cuvier's (Ziphius cavirostris), Blainville's (Mesoplodon densirostris) and an unknown species of Mesoplodon sp. (designated as Beaked Whale Gulf - BWG). For Gervais' and Cuvier's beaked whales, we estimated weekly animal density using two methods, one based on the number of echolocation clicks, and another based on the detection of animal groups during 5 min time-bins. Density estimates derived from these two methods were in good general agreement. At two sites in the western GOM, Gervais' beaked whales were present throughout the monitoring period, but Cuvier's beaked whales were present only seasonally, with periods of low density during the summer and higher density in the winter. At an eastern GOM site, both Gervais' and Cuvier's beaked whales had a high density throughout the monitoring period.

Dworshak Reservoir Kokanee Population Monitoring, Annual Report 2001.

Energy Technology Data Exchange (ETDEWEB)

Maiolie, Melo; Stark, Eric

2003-03-01

Onsite testing of strobe lights was conducted to determine if they repelled kokanee Oncorhynchus nerka away from the turbine intakes at Dworshak Dam. We tested a set of nine strobe lights flashing at a rate of 360 flashes/min placed near the intake of a 90 mW turbine. A split-beam echo sounder was used to determine the effect of strobe light operation on fish density (thought to be mostly kokanee) in front of the turbine intakes. On five nights between December 2001 and January 2002, fish density averaged 110 fish/ha when no lights were flashing. Mean density dropped to 13 fish/ha when the strobe lights were turned on during five additional nights of sampling. This 88% decline in density was significant at the P = 0.009 level of significance based on a paired Student's t test. There appeared to be no tendency for fish to habituate to the lights during the night. Test results indicate that a single set of nine lights may be sufficient to repel kokanee from a turbine intake during the night. We also used split-beam hydroacoustics to monitor the kokanee population in Dworshak Reservoir during 2001. Estimated abundance of kokanee has continued to increase since the spring of 1996 when high entrainment losses occurred. Based on hydroacoustic surveys, we estimated 3,276,000 kokanee in Dworshak Reservoir in early July 2001. This included 2,069,000 age-0 kokanee (90% CI {+-} 16.4%), 801,000 age-1 kokanee (90% CI {+-} 17.8%), and 406,000 age-2 kokanee (90% CI {+-} 20.5%). Entrainment sampling was also conducted with split-beam hydroacoustics a minimum of one continuous 24 h period per month. The highest entrainment rates occurred at night with lower discharges and shallower intake depths. Fish movement patterns suggested that they swam 'at will' in front of the intakes and may have chosen to move into the turbine intakes. Based on monthly hydroacoustic sampling in the forebay, we found that kokanee density was low in July and August during a period of high

Mammals in the areas adjacent to Forsmark and Oskarshamn. Population density, ecological data and carbon budget

Energy Technology Data Exchange (ETDEWEB)

Truve, Johan; Cederlund, Goeran [Svensk Naturfoervaltning AB, Ramsberg (Sweden)

2005-06-01

The Swedish Nuclear Fuel and Waste Management Co is in the process of selecting a safe and environmentally acceptable location for the deep-level repository of radioactive waste. SKB has expressed the importance of monitoring mammal species that are of interest both in biodiversity issues and for local hunting and recreational purposes. Two of the major goals are to: 1) monitor dynamics of population density over several years; 2) obtain information that is essential for modelling of energy/carbon flows in the biosphere and ultimately calculations of the risks of exposure to radionuclides. This report contributes to the major goals by presenting: Results from surveys of mammal abundance in the study sites near Forsmark and Oskarshamn, and a comparison with data from other surveys. A summary of traits associated to demography, resource selection and spatial distribution. A model framework that can be used to model the future development of populations. A plausible future scenario for mammal species. Mammal contribution to fluxes of energy and material in the ecosystem. Estimated harvest rates of mammals in the study sites. General conclusions that can be drawn from the survey are that population densities of the most common species are in the same range as many other populations. Lynx, wild boar, red deer and fallow deer are expanding in the areas. Marine mammals have not been surveyed but at least grey seals are important top consumers in the coastal ecosystem. Red listed species resident in the areas are Lynx, Otter, Whiskered bat, Natterer's bat, Nathusius' pipistrelle and Harbour seal. Annual production of the mammal species that were surveyed was 40-50 mg carbon/m2 and year. Hunters harvest nearly half of the production each year. Future developments for the populations are briefly discussed and a model framework that can be used to make better quantitative predictions is presented.

Mammals in the areas adjacent to Forsmark and Oskarshamn. Population density, ecological data and carbon budget

Energy Technology Data Exchange (ETDEWEB)

Truve, Johan; Cederlund, Goeran [Svensk Naturfoervaltning AB, Ramsberg (Sweden)

2005-06-01

The Swedish Nuclear Fuel and Waste Management Co is in the process of selecting a safe and environmentally acceptable location for the deep-level repository of radioactive waste. SKB has expressed the importance of monitoring mammal species that are of interest both in biodiversity issues and for local hunting and recreational purposes. Two of the major goals are to: 1) monitor dynamics of population density over several years; 2) obtain information that is essential for modelling of energy/carbon flows in the biosphere and ultimately calculations of the risks of exposure to radionuclides. This report contributes to the major goals by presenting: Results from surveys of mammal abundance in the study sites near Forsmark and Oskarshamn, and a comparison with data from other surveys. A summary of traits associated to demography, resource selection and spatial distribution. A model framework that can be used to model the future development of populations. A plausible future scenario for mammal species. Mammal contribution to fluxes of energy and material in the ecosystem. Estimated harvest rates of mammals in the study sites. General conclusions that can be drawn from the survey are that population densities of the most common species are in the same range as many other populations. Lynx, wild boar, red deer and fallow deer are expanding in the areas. Marine mammals have not been surveyed but at least grey seals are important top consumers in the coastal ecosystem. Red listed species resident in the areas are Lynx, Otter, Whiskered bat, Natterer's bat, Nathusius' pipistrelle and Harbour seal. Annual production of the mammal species that were surveyed was 40-50 mg carbon/m2 and year. Hunters harvest nearly half of the production each year. Future developments for the populations are briefly discussed and a model framework that can be used to make better quantitative predictions is presented.

Mammals in the areas adjacent to Forsmark and Oskarshamn. Population density, ecological data and carbon budget

International Nuclear Information System (INIS)

Truve, Johan; Cederlund, Goeran

2005-06-01

The Swedish Nuclear Fuel and Waste Management Co is in the process of selecting a safe and environmentally acceptable location for the deep-level repository of radioactive waste. SKB has expressed the importance of monitoring mammal species that are of interest both in biodiversity issues and for local hunting and recreational purposes. Two of the major goals are to: 1) monitor dynamics of population density over several years; 2) obtain information that is essential for modelling of energy/carbon flows in the biosphere and ultimately calculations of the risks of exposure to radionuclides. This report contributes to the major goals by presenting: Results from surveys of mammal abundance in the study sites near Forsmark and Oskarshamn, and a comparison with data from other surveys. A summary of traits associated to demography, resource selection and spatial distribution. A model framework that can be used to model the future development of populations. A plausible future scenario for mammal species. Mammal contribution to fluxes of energy and material in the ecosystem. Estimated harvest rates of mammals in the study sites. General conclusions that can be drawn from the survey are that population densities of the most common species are in the same range as many other populations. Lynx, wild boar, red deer and fallow deer are expanding in the areas. Marine mammals have not been surveyed but at least grey seals are important top consumers in the coastal ecosystem. Red listed species resident in the areas are Lynx, Otter, Whiskered bat, Natterer's bat, Nathusius' pipistrelle and Harbour seal. Annual production of the mammal species that were surveyed was 40-50 mg carbon/m2 and year. Hunters harvest nearly half of the production each year. Future developments for the populations are briefly discussed and a model framework that can be used to make better quantitative predictions is presented

Experimental evolution reveals differences between phenotypic and evolutionary responses to population density.

Science.gov (United States)

McNamara, K B; Simmons, L W

2017-09-01

Group living can select for increased immunity, given the heightened risk of parasite transmission. Yet, it also may select for increased male reproductive investment, given the elevated risk of female multiple mating. Trade-offs between immunity and reproduction are well documented. Phenotypically, population density mediates both reproductive investment and immune function in the Indian meal moth, Plodia interpunctella. However, the evolutionary response of populations to these traits is unknown. We created two replicated populations of P. interpunctella, reared and mated for 14 generations under high or low population densities. These population densities cause plastic responses in immunity and reproduction: at higher numbers, both sexes invest more in one index of immunity [phenoloxidase (PO) activity] and males invest more in sperm. Interestingly, our data revealed divergence in PO and reproduction in a different direction to previously reported phenotypic responses. Males evolving at low population densities transferred more sperm, and both males and females displayed higher PO than individuals at high population densities. These positively correlated responses to selection suggest no apparent evolutionary trade-off between immunity and reproduction. We speculate that the reduced PO activity and sperm investment when evolving under high population density may be due to the reduced population fitness predicted under increased sexual conflict and/or to trade-offs between pre- and post-copulatory traits. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Explaining density-dependent regulation in earthworm populations using life-history analysis

NARCIS (Netherlands)

Kammenga, J.E.; Spurgeon, D.J.; Svendsen, C.; Weeks, J.M.

2003-01-01

At present there is little knowledge about how density regulates population growth rate and to what extent this is determined by life-history patterns. We compared density dependent population consequences in the Nicholsonian sense based oil experimental observations and life-history modeling for

Sampling low-density gypsy moth populations

Science.gov (United States)

William E. Wallner; Clive G. Jones; Joseph S. Elkinton; Bruce L. Parker

1991-01-01

The techniques and methodology for sampling gypsy moth, Lymantria dispar L., at low densities, less than 100 egg masses/ha (EM/ha), are compared. Forest managers have constraints of time and cost, and need a useful, simple predictable means to assist them in sampling gypsy moth populations. A comparison of various techniques coupled with results of...

Sexual conflict and the evolution of asexuality at low population densities.

Science.gov (United States)

Gerber, Nina; Kokko, Hanna

2016-10-26

Theories for the evolution of sex rarely include facultatively sexual reproduction. Sexual harassment by males is an underappreciated factor: it should at first sight increase the relative advantage of asexual reproduction by increasing the cost of sex. However, if the same females can perform either sexual or asexual life cycles, then females trying to reproduce asexually may not escape harassment. If resisting male harassment is costly, it might be beneficial for a female to accept a mating and undertake a sexual life cycle rather than 'insist' on an asexual one. We investigate the effects of sexual harassment on the maintenance of sex under different population densities. Our model shows that resisting matings pays off at low population densities, which leads to the complete extinction of males, and thus to the evolution of completely asexual populations. Facultative sex persists in a narrow range of slightly higher densities. At high densities, selection favours giving up resisting male mating attempts and thus sexual reproduction takes over. These interactions between the outcomes of sexual conflict and population density suggest an explanation for the rarity of facultative sex and also patterns of geographical parthenogenesis, where marginal environments with potentially low densities are associated with asexuality. © 2016 The Author(s).

Dispersal patterns of red foxes relative to population density

Science.gov (United States)

Allen, Stephen H.; Sargeant, Alan B.

1993-01-01

Factors affecting red fox (Vulpes vulpes) dispersal patterns are poorly understood but warranted investigation because of the role of dispersal in rebuilding depleted populations and transmission of diseases. We examined dispersal patterns of red foxes in North Dakota based on recoveries of 363 of 854 foxes tagged as pups and relative to fox density. Foxes were recovered up to 8.6 years after tagging; 79% were trapped or shot. Straight-line distances between tagging and recovery locations ranged from 0 to 302 km. Mean recovery distances increased with age and were greater for males than females, but longest individual recovery distances were by females. Dispersal distances were not related to population density for males (P = 0.36) or females (P = 0.96). The proportion of males recovered that dispersed was inversely related to population density (r = -0.94; n = 5; P = 0.02), but not the proportion of females (r = -0.49; n = 5; P = 0.40). Dispersal directions were not uniform for either males (P = 0.003) or females (P = 0.006); littermates tended to disperse in similar directions (P = 0.09). A 4-lane interstate highway altered dispersal directions (P = 0.001). Dispersal is a strong innate behavior of red foxes (especially males) that results in many individuals of both sexes traveling far from natal areas. Because dispersal distance was unaffected by fox density, populations can be rebuilt and diseases transmitted long distances regardless of fox abundance.

Evaluation of population density and distribution criteria in nuclear power plant siting

International Nuclear Information System (INIS)

Young, M.

1994-06-01

The NRC has proposed revisions to 10 CFR 100 which include the codification of nuclear reactor site population density limits to 500 people per square mile, at the siting stage, averaged over any radial distance out to 30 miles, and 1,000 people per square mile within the 40-year lifetime of a nuclear plant. This study examined whether there are less restrictive alternative population density and/or distribution criteria which would provide equivalent or better protection to human health in the unlikely event of a nuclear accident. This study did not attempt to directly address the issue of actual population density limits because there are no US risk standards established for the evaluation of population density limits. Calculations were performed using source terms for both a current generation light water reactor (LWR) and an advanced light water reactor (ALWR) design. The results of this study suggest that measures which address the distribution of the population density, including emergency response conditions, could result in lower average individual risks to the public than the proposed guidelines that require controlling average population density. Studies also indicate that an exclusion zone size, determined by emergency response conditions and reactor design (power level and safety features), would better serve to protect public health than a rigid standard applied to all sites

Effect of mechanical fragmentation of sphagnum on population density and structure of micromycete communities

Science.gov (United States)

Semenova, T. A.; Golovchenko, A. V.

2017-07-01

The population density and taxonomic structure of micromycetes were monitored for six months in a model experiment with natural and mechanically fragmented (fine and coarse) samples of sphagnum. Sphagnum fragmentation favored an increase in the number of micromycetes only during the first week of the experiment. On the average, the number of micromycetes in fine-fragmented samples was two times greater than that in the coarse-fragmented samples. The diversity of micromycetes increased in the fragmented samples of sphagnum owing to the activation of some species, which remained in the inactive state as spores in the peat before fragmentation.

Anatomical traits related to stress in high density populations of Typha angustifolia L. (Typhaceae

Directory of Open Access Journals (Sweden)

F. F. Corrêa

Full Text Available Abstract Some macrophytes species show a high growth potential, colonizing large areas on aquatic environments. Cattail (Typha angustifolia L. uncontrolled growth causes several problems to human activities and local biodiversity, but this also may lead to competition and further problems for this species itself. Thus, the objective of this study was to investigate anatomical modifications on T. angustifolia plants from different population densities, once it can help to understand its biology. Roots and leaves were collected from natural populations growing under high and low densities. These plant materials were fixed and submitted to usual plant microtechnique procedures. Slides were observed and photographed under light microscopy and images were analyzed in the UTHSCSA-Imagetool software. The experimental design was completely randomized with two treatments and ten replicates, data were submitted to one-way ANOVA and Scott-Knott test at p<0.05. Leaves from low density populations showed higher stomatal density and index. These modifications on stomatal characteristics were more evident on the leaf abaxial surface. Plants from low density populations showed thicker mesophyll and higher proportion of aerenchymal area. Roots from low density populations showed a higher proportion of the vascular cylinder. Whereas, plants from higher density populations showed greater thickness of the endodermis, exodermis, phloem and root cortex. Higher density populations showed a higher proportion of aerenchymal gaps in the root cortex. Therefore, cattail plants from populations growing under high density population show anatomical traits typical of plants under stress, which promotes the development of less functional anatomical modifications to aquatic environments.

[Effect of the population density on growth and regeneration in the snail Achatina fulica].

Science.gov (United States)

Sidel'nikov, A P; Stepanov, I I

2000-01-01

In the laboratory, the growth rate of the giant African snail Achatina fulica, as estimated by the weight and shell length was shown to decrease when the population density increased from 10 to 60 snails/m2 of the total terrarium area for five months. In the second experiment, when the population density increased from 48 to 193 snails/m2, the growth rate had already decreased by six weeks. In the groups with a high population density the feeding behavior was weakened, expressed by a greater amount of nonconsumed food, according to visual observations, than in the groups with lower population densities. At the population density of 10 to 60 snails/m2, the proliferative activity in the course of the optic tentacle regeneration, as expressed by the mitotic index, did not differ reliably within five months. In the second experiment, the mitotic indices at the population densities of 96 and 193 snails/m2 within 1.5 months exceeded that of 48 snails/m2. Recommendations are given concerning the population density from the viewpoint of commercial growth of the snails. It was proposed that, based on the analysis of the mechanism underlying the inhibition of feeding behavior in populations with extra high densities, one may develop a new approach to the production of chemical agents to control land snails as agricultural pests.

Effects of social organization, trap arrangement and density, sampling scale, and population density on bias in population size estimation using some common mark-recapture estimators.

Directory of Open Access Journals (Sweden)

Manan Gupta

Full Text Available Mark-recapture estimators are commonly used for population size estimation, and typically yield unbiased estimates for most solitary species with low to moderate home range sizes. However, these methods assume independence of captures among individuals, an assumption that is clearly violated in social species that show fission-fusion dynamics, such as the Asian elephant. In the specific case of Asian elephants, doubts have been raised about the accuracy of population size estimates. More importantly, the potential problem for the use of mark-recapture methods posed by social organization in general has not been systematically addressed. We developed an individual-based simulation framework to systematically examine the potential effects of type of social organization, as well as other factors such as trap density and arrangement, spatial scale of sampling, and population density, on bias in population sizes estimated by POPAN, Robust Design, and Robust Design with detection heterogeneity. In the present study, we ran simulations with biological, demographic and ecological parameters relevant to Asian elephant populations, but the simulation framework is easily extended to address questions relevant to other social species. We collected capture history data from the simulations, and used those data to test for bias in population size estimation. Social organization significantly affected bias in most analyses, but the effect sizes were variable, depending on other factors. Social organization tended to introduce large bias when trap arrangement was uniform and sampling effort was low. POPAN clearly outperformed the two Robust Design models we tested, yielding close to zero bias if traps were arranged at random in the study area, and when population density and trap density were not too low. Social organization did not have a major effect on bias for these parameter combinations at which POPAN gave more or less unbiased population size estimates

Relationships between brightness of nighttime lights and population density

Science.gov (United States)

Naizhuo, Z.

2012-12-01

Brightness of nighttime lights has been proven to be a good proxy for socioeconomic and demographic statistics. Moreover, the satellite nighttime lights data have been used to spatially disaggregate amounts of gross domestic product (GDP), fossil fuel carbon dioxide emission, and electric power consumption (Ghosh et al., 2010; Oda and Maksyutov, 2011; Zhao et al., 2012). Spatial disaggregations were performed in these previous studies based on assumed linear relationships between digital number (DN) value of pixels in the nighttime light images and socioeconomic data. However, reliability of the linear relationships was never tested due to lack of relative high-spatial-resolution (equal to or finer than 1 km × 1 km) statistical data. With the similar assumption that brightness linearly correlates to population, Bharti et al. (2011) used nighttime light data as a proxy for population density and then developed a model about seasonal fluctuations of measles in West Africa. The Oak Ridge National Laboratory used sub-national census population data and high spatial resolution remotely-sensed-images to produce LandScan population raster datasets. The LandScan population datasets have 1 km × 1 km spatial resolution which is consistent with the spatial resolution of the nighttime light images. Therefore, in this study I selected 2008 LandScan population data as baseline reference data and the contiguous United State as study area. Relationships between DN value of pixels in the 2008 Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) stable light image and population density were established. Results showed that an exponential function can more accurately reflect the relationship between luminosity and population density than a linear function. Additionally, a certain number of saturated pixels with DN value of 63 exist in urban core areas. If directly using the exponential function to estimate the population density for the whole brightly

Population Density Modeling for Diverse Land Use Classes: Creating a National Dasymetric Worker Population Model

Science.gov (United States)

Trombley, N.; Weber, E.; Moehl, J.

2017-12-01

Many studies invoke dasymetric mapping to make more accurate depictions of population distribution by spatially restricting populations to inhabited/inhabitable portions of observational units (e.g., census blocks) and/or by varying population density among different land classes. LandScan USA uses this approach by restricting particular population components (such as residents or workers) to building area detected from remotely sensed imagery, but also goes a step further by classifying each cell of building area in accordance with ancillary land use information from national parcel data (CoreLogic, Inc.'s ParcelPoint database). Modeling population density according to land use is critical. For instance, office buildings would have a higher density of workers than warehouses even though the latter would likely have more cells of detection. This paper presents a modeling approach by which different land uses are assigned different densities to more accurately distribute populations within them. For parts of the country where the parcel data is insufficient, an alternate methodology is developed that uses National Land Cover Database (NLCD) data to define the land use type of building detection. Furthermore, LiDAR data is incorporated for many of the largest cities across the US, allowing the independent variables to be updated from two-dimensional building detection area to total building floor space. In the end, four different regression models are created to explain the effect of different land uses on worker distribution: A two-dimensional model using land use types from the parcel data A three-dimensional model using land use types from the parcel data A two-dimensional model using land use types from the NLCD data, and A three-dimensional model using land use types from the NLCD data. By and large, the resultant coefficients followed intuition, but importantly allow the relationships between different land uses to be quantified. For instance, in the model

Density dependence, density independence, and recruitment in the American shad (Alosa sapidissima) population of the Connecticut River

International Nuclear Information System (INIS)

Leggett, W.C.

1977-01-01

The role of density-dependent and density-independent factors in the regulation of the stock-recruitment relationship of the American shad (Alosa sapidissima) population of the Connecticut River was investigated. Significant reductions in egg-to-adult survival and juvenile growth rates occurred in the Holyoke--Turners Falls region in response to increases in the intensity of spawning in this area. For the Connecticut River population as a whole, egg-to-adult survival was estimated to be 0.00056 percent at replacement levels, and 0.00083 percent at the point of maximum population growth. Density-independent factors result in significant annual deviations from recruitment levels predicted by the density-dependent model. Temperature and flow regimes during spawning and early larval development are involved, but they explain only a small portion (less than 16 percent) of the total variation. In spite of an extensive data base, the accuracy of predictions concerning the potential effects of additional mortality to pre-recruit stages is low. The implications of these findings for environmental impact assessment are discussed

Connections between population density, energy use, and GHG emissions in water networks

Energy Technology Data Exchange (ETDEWEB)

Filion, Y.R. [Queen' s Univ., Kingston, ON (Canada). Dept. of Civil Engineering

2007-07-01

There is a growing concern that urban sprawl and highly dispersed urban infrastructure in cities is posing significant environmental impacts. However, there is no agreement on the suitability of interventions such as population intensification on reducing environmental impacts. This paper investigated the connection between population intensification and environmental impact in water distribution networks. Specifically, it examined the relationship between population density, annual per capita energy use, and annual per capita greenhouse gas (GHG) emissions in water distribution networks. It also examined which population densities produce low levels of annual per capita energy use and GHG emissions. An analytical model of a trunk main was developed to connect population density to energy use and GHG emissions. The model considered energy use in five life activities of the trunk main, namely pipe fabrication, pipe repair, water pumping, and pipe recycling and/or disposal. The energy use model was combined with emission factors and electricity fuel-source mixtures from four Canadian regions (Atlantic Provinces, Quebec, Ontario, and Alberta) to compute representative levels of annual per capita GHGs emitted by the trunk main. It was concluded that increasing population density from 10 ca/ha to 150 ca/ha reduced energy use and GHG emissions by 67per cent and that increasing population density beyond 150 ca/ha produces no significant decrease in annual per capita energy use and GHG emissions. Further analysis on looped networks is required to verify these preliminary findings. 10 refs., 3 tabs., 2 figs.

Inter-Population Variability of Endosymbiont Densities in the Asian Citrus Psyllid (Diaphorina citri Kuwayama).

Science.gov (United States)

Chu, Chia-Ching; Gill, Torrence A; Hoffmann, Mark; Pelz-Stelinski, Kirsten S

2016-05-01

The Asian citrus psyllid (Diaphorina citri Kuwayama) is an insect pest capable of transmitting Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening in North America. D. citri also harbors three endosymbionts, Wolbachia, Candidatus Carsonella ruddii, and Candidatus Profftella armatura, which may influence D. citri physiology and fitness. Although genomic researches on these bacteria have been conducted, much remains unclear regarding their ecology and inter-population variability in D. citri. The present work examined the densities of each endosymbiont in adult D. citri sampled from different populations using quantitative PCR. Under field conditions, the densities of all three endosymbionts positively correlated with each other, and they are associated with D. citri gender and locality. In addition, the infection density of CLas also varied across populations. Although an analysis pooling D. citri from different populations showed that CLas-infected individuals tended to have lower endosymbiont densities compared to uninfected individuals, the difference was not significant when the population was included as a factor in the analysis, suggesting that other population-specific factors may have stronger effects on endosymbiont densities. To determine whether there is a genetic basis to the density differences, endosymbiont densities between aged CLas-negative females of two D. citri populations reared under standardized laboratory conditions were compared. Results suggested that inter-population variability in Wolbachia infection density is associated with the genotypes of the endosymbiont or the host. Findings from this work could facilitate understanding of D. citri-bacterial associations that may benefit the development of approaches for managing citrus greening, such as prevention of CLas transmission.

Detection of density dependence requires density manipulations and calculation of lambda.

Science.gov (United States)

Fowler, N L; Overath, R Deborah; Pease, Craig M

2006-03-01

To investigate density-dependent population regulation in the perennial bunchgrass Bouteloua rigidiseta, we experimentally manipulated density by removing adults or adding seeds to replicate quadrats in a natural population for three annual intervals. We monitored the adjacent control quadrats for 14 annual intervals. We constructed a population projection matrix for each quadrat in each interval, calculated lambda, and did a life table response experiment (LTRE) analysis. We tested the effects of density upon lambda by comparing experimental and control quadrats, and by an analysis of the 15-year observational data set. As measured by effects on lambda and on N(t+1/Nt in the experimental treatments, negative density dependence was strong: the population was being effectively regulated. The relative contributions of different matrix elements to treatment effect on lambda differed among years and treatments; overall the pattern was one of small contributions by many different life cycle stages. In contrast, density dependence could not be detected using only the observational (control quadrats) data, even though this data set covered a much longer time span. Nor did experimental effects on separate matrix elements reach statistical significance. These results suggest that ecologists may fail to detect density dependence when it is present if they have only descriptive, not experimental, data, do not have data for the entire life cycle, or analyze life cycle components separately.

Dynamics of a low-density tiger population in Southeast Asia in the context of improved law enforcement.

Science.gov (United States)

Duangchantrasiri, Somphot; Umponjan, Mayuree; Simcharoen, Saksit; Pattanavibool, Anak; Chaiwattana, Soontorn; Maneerat, Sompoch; Kumar, N Samba; Jathanna, Devcharan; Srivathsa, Arjun; Karanth, K Ullas

2016-06-01

Recovering small populations of threatened species is an important global conservation strategy. Monitoring the anticipated recovery, however, often relies on uncertain abundance indices rather than on rigorous demographic estimates. To counter the severe threat from poaching of wild tigers (Panthera tigris), the Government of Thailand established an intensive patrolling system in 2005 to protect and recover its largest source population in Huai Kha Khaeng Wildlife Sanctuary. Concurrently, we assessed the dynamics of this tiger population over the next 8 years with rigorous photographic capture-recapture methods. From 2006 to 2012, we sampled across 624-1026 km(2) with 137-200 camera traps. Cameras deployed for 21,359 trap days yielded photographic records of 90 distinct individuals. We used closed model Bayesian spatial capture-recapture methods to estimate tiger abundances annually. Abundance estimates were integrated with likelihood-based open model analyses to estimate rates of annual and overall rates of survival, recruitment, and changes in abundance. Estimates of demographic parameters fluctuated widely: annual density ranged from 1.25 to 2.01 tigers/100 km(2) , abundance from 35 to 58 tigers, survival from 79.6% to 95.5%, and annual recruitment from 0 to 25 tigers. The number of distinct individuals photographed demonstrates the value of photographic capture-recapture methods for assessments of population dynamics in rare and elusive species that are identifiable from natural markings. Possibly because of poaching pressure, overall tiger densities at Huai Kha Khaeng were 82-90% lower than in ecologically comparable sites in India. However, intensified patrolling after 2006 appeared to reduce poaching and was correlated with marginal improvement in tiger survival and recruitment. Our results suggest that population recovery of low-density tiger populations may be slower than anticipated by current global strategies aimed at doubling the number of wild tigers

Dispersal, density dependence, and population dynamics of a fungal microbe on leaf surfaces.

Science.gov (United States)

Woody, Scott T; Ives, Anthony R; Nordheim, Erik V; Andrews, John H

2007-06-01

Despite the ubiquity and importance of microbes in nature, little is known about their natural population dynamics, especially for those that occupy terrestrial habitats. Here we investigate the dynamics of the yeast-like fungus Aureobasidium pullulans (Ap) on apple leaves in an orchard. We asked three questions. (1) Is variation in fungal population density among leaves caused by variation in leaf carrying capacities and strong density-dependent population growth that maintains densities near carrying capacity? (2) Do resident populations have competitive advantages over immigrant cells? (3) Do Ap dynamics differ at different times during the growing season? To address these questions, we performed two experiments at different times in the growing season. Both experiments used a 2 x 2 factorial design: treatment 1 removed fungal cells from leaves to reveal density-dependent population growth, and treatment 2 inoculated leaves with an Ap strain engineered to express green fluorescent protein (GFP), which made it possible to track the fate of immigrant cells. The experiments showed that natural populations of Ap vary greatly in density due to sustained differences in carrying capacities among leaves. The maintenance of populations close to carrying capacities indicates strong density-dependent processes. Furthermore, resident populations are strongly competitive against immigrants, while immigrants have little impact on residents. Finally, statistical models showed high population growth rates of resident cells in one experiment but not in the other, suggesting that Ap experiences relatively "good" and "bad" periods for population growth. This picture of Ap dynamics conforms to commonly held, but rarely demonstrated, expectations of microbe dynamics in nature. It also highlights the importance of local processes, as opposed to immigration, in determining the abundance and dynamics of microbes on surfaces in terrestrial systems.

Initial density affects biomass – density and allometric relationships in self-thinning populations of Fagopyrum esculentum

DEFF Research Database (Denmark)

Li, Lei; Weiner, Jacob; Zhou, Daowei

2013-01-01

and the biomass–density trajectory, we grew Fagopyrum esculentum populations at three high densities and measured shoot biomass, density and the height and diameter of individual plants at six harvests. * Initial density did not affect the slope of the log biomass–log density relationship, but there was a clear...... by the biomass density: the relationship between mass and volume. Initial density could affect this by altering allometric growth in a way that influences architectural compactness. An alternative hypothesis is that competition at higher initial density is more size symmetric, which has been shown to reduce...

Monitoring Population Evolution in China Using Time-Series DMSP/OLS Nightlight Imagery

Directory of Open Access Journals (Sweden)

Sisi Yu

2018-01-01

Full Text Available Accurate and detailed monitoring of population distribution and evolution is of great significance in formulating a population planning strategy in China. The Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS nighttime lights time-series (NLT image products offer a good opportunity for detecting the population distribution owing to its high correlation to human activities. However, their detection capability is greatly limited owing to a lack of in-flight calibration. At present, the synergistic use of systematically-corrected NLT products and population spatialization is rarely applied. This work proposed a methodology to improve the application precision and versatility of NLT products, explored a feasible approach to quantitatively spatialize the population to grid units of 1 km × 1 km , and revealed the spatio-temporal characteristics of population distribution from 2000 to 2010. Results indicated that, (1 after inter-calibration, geometric, incompatibility and discontinuity corrections, and adjustment based on vegetation information, the incompatibility and discontinuity of NTL products were successfully solved. Accordingly, detailed actual residential areas and luminance differences between the urban core and the peripheral regions could be obtained. (2 The population spatialization method could effectively acquire population information at per km 2 with high accuracy and exhibit more details in the evolution of population distribution. (3 Obvious differences in spatio-temporal characteristics existed in four economic regions, from the aspects of population distribution and dynamics, as well as population-weighted centroids. The eastern region was the most populous with the largest increased magnitude, followed by the central, northeastern, and western regions. The population-weighted centroids of the eastern, western, and northeastern regions moved along the southwest direction, while the population

The demography of climate-driven and density-regulated population dynamics in a perennial plant

DEFF Research Database (Denmark)

Dahlgren, Johan; Bengstsson, Karin; Ehrlén, Johan

2016-01-01

Identifying the internal and external drivers of population dynamics is a key objective in ecology, currently accentuated by the need to forecast the effects of climate change on species distributions and abundances. The interplay between environmental and density effects is one particularly...... important aspect of such forecasts. We examined the simultaneous impact of climate and intraspecific density on vital rates of the dwarf shrub Fumana procumbens over 20 yr, using generalized additive mixed models. We then analyzed effects on population dynamics using integral projection models...... to be driven solely by the environment can overestimate extinction risks if there is density dependence. We conclude that density regulation can dampen effects of climate change on Fumana population size, and discuss the need to quantify density dependence in predictions of population responses...

Discontinuous Galerkin finite element method for solving population density functions of cortical pyramidal and thalamic neuronal populations.

Science.gov (United States)

Huang, Chih-Hsu; Lin, Chou-Ching K; Ju, Ming-Shaung

2015-02-01

Compared with the Monte Carlo method, the population density method is efficient for modeling collective dynamics of neuronal populations in human brain. In this method, a population density function describes the probabilistic distribution of states of all neurons in the population and it is governed by a hyperbolic partial differential equation. In the past, the problem was mainly solved by using the finite difference method. In a previous study, a continuous Galerkin finite element method was found better than the finite difference method for solving the hyperbolic partial differential equation; however, the population density function often has discontinuity and both methods suffer from a numerical stability problem. The goal of this study is to improve the numerical stability of the solution using discontinuous Galerkin finite element method. To test the performance of the new approach, interaction of a population of cortical pyramidal neurons and a population of thalamic neurons was simulated. The numerical results showed good agreement between results of discontinuous Galerkin finite element and Monte Carlo methods. The convergence and accuracy of the solutions are excellent. The numerical stability problem could be resolved using the discontinuous Galerkin finite element method which has total-variation-diminishing property. The efficient approach will be employed to simulate the electroencephalogram or dynamics of thalamocortical network which involves three populations, namely, thalamic reticular neurons, thalamocortical neurons and cortical pyramidal neurons. Copyright © 2014 Elsevier Ltd. All rights reserved.

Measurements of beam halo diffusion and population density in the Tevatron and in the Large Hadron Collider

Energy Technology Data Exchange (ETDEWEB)

Stancari, Giulio [Fermilab

2015-03-01

Halo dynamics influences global accelerator performance: beam lifetimes, emittance growth, dynamic aperture, and collimation efficiency. Halo monitoring and control are also critical for the operation of high-power machines. For instance, in the high-luminosity upgrade of the LHC, the energy stored in the beam tails may reach several megajoules. Fast losses can result in superconducting magnet quenches, magnet damage, or even collimator deformation. The need arises to measure the beam halo and to remove it at controllable rates. In the Tevatron and in the LHC, halo population densities and diffusivities were measured with collimator scans by observing the time evolution of losses following small inward or outward collimator steps, under different experimental conditions: with single beams and in collision, and, in the case of the Tevatron, with a hollow electron lens acting on a subset of bunches. After the LHC resumes operations, it is planned to compare measured diffusivities with the known strength of transverse damper excitations. New proposals for nondestructive halo population density measurements are also briefly discussed.

Understanding spatial connectivity of individuals with non-uniform population density.

Science.gov (United States)

Wang, Pu; González, Marta C

2009-08-28

We construct a two-dimensional geometric graph connecting individuals placed in space within a given contact distance. The individuals are distributed using a measured country's density of population. We observe that while large clusters (group of individuals connected) emerge within some regions, they are trapped in detached urban areas owing to the low population density of the regions bordering them. To understand the emergence of a giant cluster that connects the entire population, we compare the empirical geometric graph with the one generated by placing the same number of individuals randomly in space. We find that, for small contact distances, the empirical distribution of population dominates the growth of connected components, but no critical percolation transition is observed in contrast to the graph generated by a random distribution of population. Our results show that contact distances from real-world situations as for WIFI and Bluetooth connections drop in a zone where a fully connected cluster is not observed, hinting that human mobility must play a crucial role in contact-based diseases and wireless viruses' large-scale spreading.

Tiller size/population density compensation in grazed Coastcross bermudagrass swards

Directory of Open Access Journals (Sweden)

Sbrissia André Fischer

2001-01-01

Full Text Available Several compensatory mechanisms in pastures do not allow optimisation of responses from the processes of herbage production and utilisation. Compensation due to tiller size/density relationships is one of these mechanisms. This experiment evaluated this process for Coastcross bermudagrass and compared the responses to those reported for temperate forages. Treatments were "steady state" sward surface heights of 5, 10, 15, and 20 cm that were maintained from August, 1998, through July, 1999 by sheep grazing. The experimental design was a randomised complete block, replicated four times. Pasture responses were evaluated on four separate dates (15/12/1998, 25/01/1999, 07/04/1999 and 04/07/1999 with respect to: tiller population density, tiller weight, leaf mass and leaf area per tiller and herbage mass (biomass. Tiller volume, leaf area index (LAI, tiller leaf:stem ratio and tiller leaf area:volume ratio (R were calculated. Simple regression analyses between tiller population density and tiller weight were also performed. Coastcross swards showed a tiller size/density compensation mechanism where high tiller population densities were associated with small tillers and vice-versa; except on the last evaluation. However, regression analysis revealed linear coefficients of -3.83 to -2.05, which are lower than the theoretical expectation of -3/2. The lower R values observed, when compared to those reported for perennial ryegrass, suggest that Coastcross swards optimised their LAI via clonal integration among tillers in contrast with tillers of cool-season grasses that respond more as individuals. However, this hypothesis has yet to be experimentally verified.

Monitoring of dose rates and radiation flux density in working rooms

International Nuclear Information System (INIS)

Krajtor, S.N.

1980-01-01

The problems of determining the neutron field characteristics (dose equivalent rate and flux density) in relation to the environmental monitoring by radiation protection services. The measurement devices used for measuring dose equivalent rate and neutron flux density RUS-U8 multi-purpose scintillation radiometer and RUP-1 multi-purpose transportable radiometer as well as measurement technique are described. Recommendations are given for checking measuring devices calibration, registering measurement results [ru

Population densities of wheat thrips, Haplothrips tritici Kurdjumov ...

African Journals Online (AJOL)

Jane

2011-07-18

Jul 18, 2011 ... Key words: Thysanoptera, Haplothrips tritici, population density, bread wheat, durum wheat, barley, cultivars. INTRODUCTION. Some thrips types of the order Thysanoptera constitute one of the harmful groups found on grains (Minaei and. Mound, 2008). The most common species observed on grains in ...

Wireless-accessible sensor populations for monitoring biological variables

NARCIS (Netherlands)

Mazzu, Marco; Scalvini, Simonetta; Giordano, A.; Frumento, E.; Wells, Hannah; Lokhorst, C.; Glisenti, Fulvio

2008-01-01

The current health-care infrastructure is generally considered to be inadequate to meet the needs of an increasingly older population. We have investigated the feasibility of a passive in-home monitoring system based on wireless accessible sensor populations (WASP). In an EU-funded project we have

Monitoring carnivore populations at the landscape scale: occupancy modelling of tigers from sign surveys

Science.gov (United States)

Karanth, Kota Ullas; Gopalaswamy, Arjun M.; Kumar, Narayanarao Samba; Vaidyanathan, Srinivas; Nichols, James D.; MacKenzie, Darryl I.

2011-01-01

1. Assessing spatial distributions of threatened large carnivores at landscape scales poses formidable challenges because of their rarity and elusiveness. As a consequence of logistical constraints, investigators typically rely on sign surveys. Most survey methods, however, do not explicitly address the central problem of imperfect detections of animal signs in the field, leading to underestimates of true habitat occupancy and distribution. 2. We assessed habitat occupancy for a tiger Panthera tigris metapopulation across a c. 38 000-km2 landscape in India, employing a spatially replicated survey to explicitly address imperfect detections. Ecological predictions about tiger presence were confronted with sign detection data generated from occupancy sampling of 205 sites, each of 188 km2. 3. A recent occupancy model that considers Markovian dependency among sign detections on spatial replicates performed better than the standard occupancy model (ΔAIC = 184·9). A formulation of this model that fitted the data best showed that density of ungulate prey and levels of human disturbance were key determinants of local tiger presence. Model averaging resulted in a replicate-level detection probability [inline image] = 0·17 (0·17) for signs and a tiger habitat occupancy estimate of [inline image] = 0·665 (0·0857) or 14 076 (1814) km2 of potential habitat of 21 167 km2. In contrast, a traditional presence-versus-absence approach underestimated occupancy by 47%. Maps of probabilities of local site occupancy clearly identified tiger source populations at higher densities and matched observed tiger density variations, suggesting their potential utility for population assessments at landscape scales. 4. Synthesis and applications. Landscape-scale sign surveys can efficiently assess large carnivore spatial distributions and elucidate the factors governing their local presence, provided ecological and observation processes are both explicitly modelled. Occupancy

Nutritional Correlates of Koala Persistence in a Low-Density Population

Science.gov (United States)

Stalenberg, Eleanor; Wallis, Ian R.; Cunningham, Ross B.; Allen, Chris; Foley, William J.

2014-01-01

It is widely postulated that nutritional factors drive bottom-up, resource-based patterns in herbivore ecology and distribution. There is, however, much controversy over the roles of different plant constituents and how these influence individual herbivores and herbivore populations. The density of koala (Phascolarctos cinereus) populations varies widely and many attribute population trends to variation in the nutritional quality of the eucalypt leaves of their diet, but there is little evidence to support this hypothesis. We used a nested design that involved sampling of trees at two spatial scales to investigate how leaf chemistry influences free-living koalas from a low-density population in south east New South Wales, Australia. Using koala faecal pellets as a proxy for koala visitation to trees, we found an interaction between toxins and nutrients in leaves at a small spatial scale, whereby koalas preferred trees with leaves of higher concentrations of available nitrogen but lower concentrations of sideroxylonals (secondary metabolites found exclusively in eucalypts) compared to neighbouring trees of the same species. We argue that taxonomic and phenotypic diversity is likely to be important when foraging in habitats of low nutritional quality in providing diet choice to tradeoff nutrients and toxins and minimise movement costs. Our findings suggest that immediate nutritional concerns are an important priority of folivores in low-quality habitats and imply that nutritional limitations play an important role in constraining folivore populations. We show that, with a careful experimental design, it is possible to make inferences about populations of herbivores that exist at extremely low densities and thus achieve a better understanding about how plant composition influences herbivore ecology and persistence. PMID:25470599

Nutritional correlates of koala persistence in a low-density population.

Directory of Open Access Journals (Sweden)

Eleanor Stalenberg

Full Text Available It is widely postulated that nutritional factors drive bottom-up, resource-based patterns in herbivore ecology and distribution. There is, however, much controversy over the roles of different plant constituents and how these influence individual herbivores and herbivore populations. The density of koala (Phascolarctos cinereus populations varies widely and many attribute population trends to variation in the nutritional quality of the eucalypt leaves of their diet, but there is little evidence to support this hypothesis. We used a nested design that involved sampling of trees at two spatial scales to investigate how leaf chemistry influences free-living koalas from a low-density population in south east New South Wales, Australia. Using koala faecal pellets as a proxy for koala visitation to trees, we found an interaction between toxins and nutrients in leaves at a small spatial scale, whereby koalas preferred trees with leaves of higher concentrations of available nitrogen but lower concentrations of sideroxylonals (secondary metabolites found exclusively in eucalypts compared to neighbouring trees of the same species. We argue that taxonomic and phenotypic diversity is likely to be important when foraging in habitats of low nutritional quality in providing diet choice to tradeoff nutrients and toxins and minimise movement costs. Our findings suggest that immediate nutritional concerns are an important priority of folivores in low-quality habitats and imply that nutritional limitations play an important role in constraining folivore populations. We show that, with a careful experimental design, it is possible to make inferences about populations of herbivores that exist at extremely low densities and thus achieve a better understanding about how plant composition influences herbivore ecology and persistence.

Monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm on permanent plots: sampling methods and statistical properties of data

Science.gov (United States)

A.R. Mason; H.G. Paul

1994-01-01

Procedures for monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm are recommended based on many years experience in sampling these species in eastern Oregon and Washington. It is shown that statistically reliable estimates of larval density can be made for a population by sampling host trees in a series of permanent plots in a...

Indicator Species Population Monitoring in Antarctica with Uav

Science.gov (United States)

Zmarz, A.; Korczak-Abshire, M.; Storvold, R.; Rodzewicz, M.; Kędzierska, I.

2015-08-01

A program to monitor bird and pinniped species in the vicinity of Arctowski Station, King George Island, South Shetlands, Antarctica, has been conducted over the past 38 years. Annual monitoring of these indicator species includes estimations of breeding population sizes of three Pygoscelis penguin species: Adélie, gentoo and chinstrap. Six penguin colonies situated on the western shores of two bays: Admiralty and King George are investigated. To study changes in penguin populations Unmanned Aerial Vehicles were used for the first time in the 2014/15 austral summer season. During photogrammetric flights the high-resolution images of eight penguin breeding colonies were taken. Obtained high resolution images were used for estimation of breeding population size and compared with the results of measurements taken at the same time from the ground. During this Antarctic expedition eight successful photogrammetry missions (total distance 1500 km) were performed. Images were taken with digital SLR Canon 700D, Nikon D5300, Nikon D5100 with a 35mm objective lens. Flights altitude at 350 - 400 AGL, allowed images to be taken with a resolution GSD (ground sample distance) less than 5 cm. The Image J software analysis method was tested to provide automatic population estimates from obtained images. The use of UAV for monitoring of indicator species, enabled data acquisition from areas inaccessible by ground methods.

INDICATOR SPECIES POPULATION MONITORING IN ANTARCTICA WITH UAV

Directory of Open Access Journals (Sweden)

A. Zmarz

2015-08-01

Full Text Available A program to monitor bird and pinniped species in the vicinity of Arctowski Station, King George Island, South Shetlands, Antarctica, has been conducted over the past 38 years. Annual monitoring of these indicator species includes estimations of breeding population sizes of three Pygoscelis penguin species: Adélie, gentoo and chinstrap. Six penguin colonies situated on the western shores of two bays: Admiralty and King George are investigated. To study changes in penguin populations Unmanned Aerial Vehicles were used for the first time in the 2014/15 austral summer season. During photogrammetric flights the high-resolution images of eight penguin breeding colonies were taken. Obtained high resolution images were used for estimation of breeding population size and compared with the results of measurements taken at the same time from the ground. During this Antarctic expedition eight successful photogrammetry missions (total distance 1500 km were performed. Images were taken with digital SLR Canon 700D, Nikon D5300, Nikon D5100 with a 35mm objective lens. Flights altitude at 350 – 400 AGL, allowed images to be taken with a resolution GSD (ground sample distance less than 5 cm. The Image J software analysis method was tested to provide automatic population estimates from obtained images. The use of UAV for monitoring of indicator species, enabled data acquisition from areas inaccessible by ground methods.

Population densities of wheat thrips, Haplothrips tritici Kurdjumov ...

African Journals Online (AJOL)

Population densities of Haplothrips tritici (H. tritici) Kurdjumov (Thysanoptera: Phlaeothripidae) were studied in Kahramanmaras, Turkey. In 2002, bread wheat cultivars, Bocro 4, Pehlivan and Yüreğir 89, durum wheat cultivars, Balcali 85, Ceylan 95 and Harran 95 and barley cultivars, Esterel and Pacific, were used. In 2003 ...

Population Density Modulates Drug Inhibition and Gives Rise to Potential Bistability of Treatment Outcomes for Bacterial Infections.

Directory of Open Access Journals (Sweden)

Jason Karslake

2016-10-01

Full Text Available The inoculum effect (IE is an increase in the minimum inhibitory concentration (MIC of an antibiotic as a function of the initial size of a microbial population. The IE has been observed in a wide range of bacteria, implying that antibiotic efficacy may depend on population density. Such density dependence could have dramatic effects on bacterial population dynamics and potential treatment strategies, but explicit measures of per capita growth as a function of density are generally not available. Instead, the IE measures MIC as a function of initial population size, and population density changes by many orders of magnitude on the timescale of the experiment. Therefore, the functional relationship between population density and antibiotic inhibition is generally not known, leaving many questions about the impact of the IE on different treatment strategies unanswered. To address these questions, here we directly measured real-time per capita growth of Enterococcus faecalis populations exposed to antibiotic at fixed population densities using multiplexed computer-automated culture devices. We show that density-dependent growth inhibition is pervasive for commonly used antibiotics, with some drugs showing increased inhibition and others decreased inhibition at high densities. For several drugs, the density dependence is mediated by changes in extracellular pH, a community-level phenomenon not previously linked with the IE. Using a simple mathematical model, we demonstrate how this density dependence can modulate population dynamics in constant drug environments. Then, we illustrate how time-dependent dosing strategies can mitigate the negative effects of density-dependence. Finally, we show that these density effects lead to bistable treatment outcomes for a wide range of antibiotic concentrations in a pharmacological model of antibiotic treatment. As a result, infections exceeding a critical density often survive otherwise effective treatments.

Estimating population density for disease risk assessment: The importance of understanding the area of influence of traps using wild pigs as an example.

Science.gov (United States)

Davis, Amy J; Leland, Bruce; Bodenchuk, Michael; VerCauteren, Kurt C; Pepin, Kim M

2017-06-01

Population density is a key driver of disease dynamics in wildlife populations. Accurate disease risk assessment and determination of management impacts on wildlife populations requires an ability to estimate population density alongside management actions. A common management technique for controlling wildlife populations to monitor and mitigate disease transmission risk is trapping (e.g., box traps, corral traps, drop nets). Although abundance can be estimated from trapping actions using a variety of analytical approaches, inference is limited by the spatial extent to which a trap attracts animals on the landscape. If the "area of influence" were known, abundance estimates could be converted to densities. In addition to being an important predictor of contact rate and thus disease spread, density is more informative because it is comparable across sites of different sizes. The goal of our study is to demonstrate the importance of determining the area sampled by traps (area of influence) so that density can be estimated from management-based trapping designs which do not employ a trapping grid. To provide one example of how area of influence could be calculated alongside management, we conducted a small pilot study on wild pigs (Sus scrofa) using two removal methods 1) trapping followed by 2) aerial gunning, at three sites in northeast Texas in 2015. We estimated abundance from trapping data with a removal model. We calculated empirical densities as aerial counts divided by the area searched by air (based on aerial flight tracks). We inferred the area of influence of traps by assuming consistent densities across the larger spatial scale and then solving for area impacted by the traps. Based on our pilot study we estimated the area of influence for corral traps in late summer in Texas to be ∼8.6km 2 . Future work showing the effects of behavioral and environmental factors on area of influence will help mangers obtain estimates of density from management data, and

Partitioning the sources of demographic variation reveals density-dependent nest predation in an island bird population.

Science.gov (United States)

Sofaer, Helen R; Sillett, T Scott; Langin, Kathryn M; Morrison, Scott A; Ghalambor, Cameron K

2014-07-01

Ecological factors often shape demography through multiple mechanisms, making it difficult to identify the sources of demographic variation. In particular, conspecific density can influence both the strength of competition and the predation rate, but density-dependent competition has received more attention, particularly among terrestrial vertebrates and in island populations. A better understanding of how both competition and predation contribute to density-dependent variation in fecundity can be gained by partitioning the effects of density on offspring number from its effects on reproductive failure, while also evaluating how biotic and abiotic factors jointly shape demography. We examined the effects of population density and precipitation on fecundity, nest survival, and adult survival in an insular population of orange-crowned warblers (Oreothlypis celata) that breeds at high densities and exhibits a suite of traits suggesting strong intraspecific competition. Breeding density had a negative influence on fecundity, but it acted by increasing the probability of reproductive failure through nest predation, rather than through competition, which was predicted to reduce the number of offspring produced by successful individuals. Our results demonstrate that density-dependent nest predation can underlie the relationship between population density and fecundity even in a high-density, insular population where intraspecific competition should be strong.

Population dynamics of three songbird species in a nestbox population in Central Europe show effects of density, climate and competitive interactions

NARCIS (Netherlands)

Smallegange, I.M.; van der Meer, J.; Fiedler, W.

2011-01-01

Unravelling the contributions of density-dependent and density-independent factors in determining species population dynamics is a challenge, especially if the two factors interact. One approach is to apply stochastic population models to long-term data, yet few studies have included interactions

Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density

DEFF Research Database (Denmark)

Vinther, Morten; Eero, Margit

2013-01-01

Evaluations of the effects of management measures on fish populations are usually based on the analyses of population dynamics and estimates of fishing mortality from stock assessments. However, this approach may not be applicable in all cases, in particular for data-limited stocks, which may...... GAM analyses to predict local cod densities and combine this with spatio-temporal data of fishing effort based on VMS (Vessel Monitoring System). To quantify local fishing impact on the stock, retention probability of the gears is taken into account. The results indicate a substantial decline...... in the impact of the Danish demersal trawl fleet on cod in the Kattegat in recent years, due to a combination of closed areas, introduction of selective gears and changes in overall effort....

Sociodemographic Factors, Population Density, and Bicycling for Transportation in the United States.

Science.gov (United States)

Nehme, Eileen K; Pérez, Adriana; Ranjit, Nalini; Amick, Benjamin C; Kohl, Harold W

2016-01-01

Transportation bicycling is a behavior with demonstrated health benefits. Population-representative studies of transportation bicycling in United States are lacking. This study examined associations between sociodemographic factors, population density, and transportation bicycling and described transportation bicyclists by trip purposes, using a US-representative sample. This cross-sectional study used 2009 National Household Travel Survey datasets. Associations among study variables were assessed using weighted multivariable logistic regression. On a typical day in 2009, 1% of Americans older than 5 years of age reported a transportation bicycling trip. Transportation cycling was inversely associated with age and directly with being male, with being white, and with population density (≥ 10,000 vs transportation. Twenty-one percent of transportation bicyclists reported trips to work, whereas 67% reported trips to social or other activities. Transportation bicycling in the United States is associated with sociodemographic characteristics and population density. Bicycles are used for a variety of trip purposes, which has implications for transportation bicycling research based on commuter data and for developing interventions to promote this behavior.

Allometric scaling of population variance with mean body size is predicted from Taylor's law and density-mass allometry.

Science.gov (United States)

Cohen, Joel E; Xu, Meng; Schuster, William S F

2012-09-25

Two widely tested empirical patterns in ecology are combined here to predict how the variation of population density relates to the average body size of organisms. Taylor's law (TL) asserts that the variance of the population density of a set of populations is a power-law function of the mean population density. Density-mass allometry (DMA) asserts that the mean population density of a set of populations is a power-law function of the mean individual body mass. Combined, DMA and TL predict that the variance of the population density is a power-law function of mean individual body mass. We call this relationship "variance-mass allometry" (VMA). We confirmed the theoretically predicted power-law form and the theoretically predicted parameters of VMA, using detailed data on individual oak trees (Quercus spp.) of Black Rock Forest, Cornwall, New York. These results connect the variability of population density to the mean body mass of individuals.

Population density models of integrate-and-fire neurons with jumps: well-posedness.

Science.gov (United States)

Dumont, Grégory; Henry, Jacques

2013-09-01

In this paper we study the well-posedness of different models of population of leaky integrate-and-fire neurons with a population density approach. The synaptic interaction between neurons is modeled by a potential jump at the reception of a spike. We study populations that are self excitatory or self inhibitory. We distinguish the cases where this interaction is instantaneous from the one where there is a repartition of conduction delays. In the case of a bounded density of delays both excitatory and inhibitory population models are shown to be well-posed. But without conduction delay the solution of the model of self excitatory neurons may blow up. We analyze the different behaviours of the model with jumps compared to its diffusion approximation.

Evidence of a high density population of harvested leopards in a montane environment.

Science.gov (United States)

Chase Grey, Julia N; Kent, Vivien T; Hill, Russell A

2013-01-01

Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus) population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR) analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications.

Evidence of a high density population of harvested leopards in a montane environment.

Directory of Open Access Journals (Sweden)

Julia N Chase Grey

Full Text Available Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications.

Larval Population Density Alters Adult Sleep in Wild-Type Drosophila melanogaster but Not in Amnesiac Mutant Flies

Directory of Open Access Journals (Sweden)

Michael W. Chi

2014-08-01

Full Text Available Sleep has many important biological functions, but how sleep is regulated remains poorly understood. In humans, social isolation and other stressors early in life can disrupt adult sleep. In fruit flies housed at different population densities during early adulthood, social enrichment was shown to increase subsequent sleep, but it is unknown if population density during early development can also influence adult sleep. To answer this question, we maintained Drosophila larvae at a range of population densities throughout larval development, kept them isolated during early adulthood, and then tested their sleep patterns. Our findings reveal that flies that had been isolated as larvae had more fragmented sleep than those that had been raised at higher population densities. This effect was more prominent in females than in males. Larval population density did not affect sleep in female flies that were mutant for amnesiac, which has been shown to be required for normal memory consolidation, adult sleep regulation, and brain development. In contrast, larval population density effects on sleep persisted in female flies lacking the olfactory receptor or83b, suggesting that olfactory signals are not required for the effects of larval population density on adult sleep. These findings show that population density during early development can alter sleep behavior in adulthood, suggesting that genetic and/or structural changes are induced by this developmental manipulation that persist through metamorphosis.

High coffee population density to improve fertility of an oxisol

OpenAIRE

Pavan,Marcos Antonio; Chaves,Júlio César Dias; Siqueira,Rubens; Androcioli Filho,Armando; Colozzi Filho,Arnaldo; Balota,Elcio Liborio

1999-01-01

The objective of this work was to evaluate the effect of coffee (Coffea arabica L.) population densities on the chemical and microbiological properties of an Oxisol. The work was carried out on soil samples of 0-20 cm depth originated from an experimental site which had been used for coffee tree spacing studies during 15 years, in Paraná State, Brazil. Eight coffee tree populations were evaluated: 7143, 3571, 2381, 1786, 1429, 1190, 1020, and 893 trees/ha. Increasing plant population increase...

Local environment and density-dependent feedbacks determine population growth in a forest herb

DEFF Research Database (Denmark)

Dahlgren, Johan Petter; Östergård, Hannah; Ehrlén, Johan

2014-01-01

Linking spatial variation in environmental factors to variation in demographic rates is essential for a mechanistic understanding of the dynamics of populations. However, we still know relatively little about such links, partly because feedbacks via intraspecific density make them difficult...... to observe in natural populations. We conducted a detailed field study and investigated simultaneous effects of environmental factors and the intraspecific density of individuals on the demography of the herb Lathyrus vernus. In regression models of vital rates we identified effects associated with spring...... shade on survival and growth, while density was negatively correlated with these vital rates. Density was also negatively correlated with average individual size in the study plots, which is consistent with self-thinning. In addition, average plant sizes were larger than predicted by density in plots...

Grain yield of corn at different population densities and intercropped with forages

Directory of Open Access Journals (Sweden)

José M. do Nascimento

2015-12-01

Full Text Available ABSTRACT The no-tillage system optimizes agricultural areas, maintaining the supply of straw and promoting crop rotation and soil conservation. The aim of the present study was to evaluate sowing quality and grain yield of corn intercropped with three forage species of the Urochloa genus associated with two corn population densities. The experiment was conducted at the São Paulo State University (UNESP, in Jaboticabal-SP, Brazil. The experimental design was randomized blocks in a 2 x 3 factorial scheme with four replicates. The treatments consisted of two corn densities (55,000 and 75,000 plants ha-1 intercropped with three forages (Urochloa brizantha, Urochloa decumbens and Urochloa ruziziensis sown between rows of corn in the V4 stage. The following corn variables were analysed: mean number of days for emergence, longitudinal distribution, grain yield, initial population and final population. There were differences between corn populations (p < 0.1 and the intercropping of corn with the species U. brizantha and U. ruziziensis promoted the best results, which permitted concluding that the cultivation of corn at the population density of 75,000 plants ha-1 intercropped U. brizantha and U. ruziziensis promoted better sowing quality and, consequently, higher grain yields.

From echolocation clicks to animal density – acoustic sampling of harbour porpoises with static dataloggers

DEFF Research Database (Denmark)

Kyhn, Line Anker; Tougaard, Jakob; Thomas, L.

2012-01-01

Monitoring abundance and population trends of small odontocetes is notoriously difficult and labour intensive. There is a need to develop alternative methods to the traditional visual line transect surveys, especially for low density areas. Here, the prospect of obtaining robust density estimates....... This provides a method suitable for monitoring in areas with densities too low for visual surveys to be practically feasible, e.g. the endangered harbour porpoise population in the Baltic....... for porpoises by passive acoustic monitoring (PAM) is demonstrated by combining rigorous application of methods adapted from distance sampling to PAM. Acoustic dataloggers (T-PODs) were deployed in an area where harbour porpoises concurrently were tracked visually. Probability of detection was estimated...

Semivariogram models for estimating fig fly population density throughout the year

Directory of Open Access Journals (Sweden)

Mauricio Paulo Batistella Pasini

2014-07-01

Full Text Available The objective of this work was to select semivariogram models to estimate the population density of fig fly (Zaprionus indianus; Diptera: Drosophilidae throughout the year, using ordinary kriging. Nineteen monitoring sites were demarcated in an area of 8,200 m2, cropped with six fruit tree species: persimmon, citrus, fig, guava, apple, and peach. During a 24 month period, 106 weekly evaluations were done in these sites. The average number of adult fig flies captured weekly per trap, during each month, was subjected to the circular, spherical, pentaspherical, exponential, Gaussian, rational quadratic, hole effect, K-Bessel, J-Bessel, and stable semivariogram models, using ordinary kriging interpolation. The models with the best fit were selected by cross-validation. Each data set (months has a particular spatial dependence structure, which makes it necessary to define specific models of semivariograms in order to enhance the adjustment to the experimental semivariogram. Therefore, it was not possible to determine a standard semivariogram model; instead, six theoretical models were selected: circular, Gaussian, hole effect, K-Bessel, J-Bessel, and stable.

Population density shapes patterns of survival and reproduction in Eleutheria dichotoma (Hydrozoa: Anthoathecata).

Science.gov (United States)

Dańko, Aleksandra; Schaible, Ralf; Pijanowska, Joanna; Dańko, Maciej J

2018-01-01

Budding hydromedusae have high reproductive rates due to asexual reproduction and can occur in high population densities along the coasts, specifically in tidal pools. In laboratory experiments, we investigated the effects of population density on the survival and reproductive strategies of a single clone of Eleutheria dichotoma . We found that sexual reproduction occurs with the highest rate at medium population densities. Increased sexual reproduction was associated with lower budding (asexual reproduction) and survival probability. Sexual reproduction results in the production of motile larvae that can, in contrast to medusae, seek to escape unfavorable conditions by actively looking for better environments. The successful settlement of a larva results in starting the polyp stage, which is probably more resistant to environmental conditions. This is the first study that has examined the life-history strategies of the budding hydromedusa E. dichotoma by conducting a long-term experiment with a relatively large sample size that allowed for the examination of age-specific mortality and reproductive rates. We found that most sexual and asexual reproduction occurred at the beginning of life following a very rapid process of maturation. The parametric models fitted to the mortality data showed that population density was associated with an increase in the rate of aging, an increase in the level of late-life mortality plateau, and a decrease in the hidden heterogeneity in individual mortality rates. The effects of population density on life-history traits are discussed in the context of resource allocation and the r/K-strategies' continuum concept.

Combining Science and Traditional Ecological Knowledge: Monitoring Populations for Co-Management

Directory of Open Access Journals (Sweden)

Henrik Moller

2004-12-01

Full Text Available Using a combination of traditional ecological knowledge and science to monitor populations can greatly assist co-management for sustainable customary wildlife harvests by indigenous peoples. Case studies from Canada and New Zealand emphasize that, although traditional monitoring methods may often be imprecise and qualitative, they are nevertheless valuable because they are based on observations over long time periods, incorporate large sample sizes, are inexpensive, invite the participation of harvesters as researchers, and sometimes incorporate subtle multivariate cross checks for environmental change. A few simple rules suggested by traditional knowledge may produce good management outcomes consistent with fuzzy logic thinking. Science can sometimes offer better tests of potential causes of population change by research on larger spatial scales, precise quantification, and evaluation of population change where no harvest occurs. However, science is expensive and may not always be trusted or welcomed by customary users of wildlife. Short scientific studies in which traditional monitoring methods are calibrated against population abundance could make it possible to mesh traditional ecological knowledge with scientific inferences of prey population dynamics. This paper analyzes the traditional monitoring techniques of catch per unit effort and body condition. Combining scientific and traditional monitoring methods can not only build partnership and community consensus, but also, and more importantly, allow indigenous wildlife users to critically evaluate scientific predictions on their own terms and test sustainability using their own forms of adaptive management.

Density dependence governs when population responses to multiple stressors are magnified or mitigated.

Science.gov (United States)

Hodgson, Emma E; Essington, Timothy E; Halpern, Benjamin S

2017-10-01

Population endangerment typically arises from multiple, potentially interacting anthropogenic stressors. Extensive research has investigated the consequences of multiple stressors on organisms, frequently focusing on individual life stages. Less is known about population-level consequences of exposure to multiple stressors, especially when exposure varies through life. We provide the first theoretical basis for identifying species at risk of magnified effects from multiple stressors across life history. By applying a population modeling framework, we reveal conditions under which population responses from stressors applied to distinct life stages are either magnified (synergistic) or mitigated. We find that magnification or mitigation critically depends on the shape of density dependence, but not the life stage in which it occurs. Stressors are always magnified when density dependence is linear or concave, and magnified or mitigated when it is convex. Using Bayesian numerical methods, we estimated the shape of density dependence for eight species across diverse taxa, finding support for all three shapes. © 2017 by the Ecological Society of America.

Inference about density and temporary emigration in unmarked populations

Science.gov (United States)

Chandler, Richard B.; Royle, J. Andrew; King, David I.

2011-01-01

Few species are distributed uniformly in space, and populations of mobile organisms are rarely closed with respect to movement, yet many models of density rely upon these assumptions. We present a hierarchical model allowing inference about the density of unmarked populations subject to temporary emigration and imperfect detection. The model can be fit to data collected using a variety of standard survey methods such as repeated point counts in which removal sampling, double-observer sampling, or distance sampling is used during each count. Simulation studies demonstrated that parameter estimators are unbiased when temporary emigration is either "completely random" or is determined by the size and location of home ranges relative to survey points. We also applied the model to repeated removal sampling data collected on Chestnut-sided Warblers (Dendroica pensylvancia) in the White Mountain National Forest, USA. The density estimate from our model, 1.09 birds/ha, was similar to an estimate of 1.11 birds/ha produced by an intensive spot-mapping effort. Our model is also applicable when processes other than temporary emigration affect the probability of being available for detection, such as in studies using cue counts. Functions to implement the model have been added to the R package unmarked.

The trans-generational impact of population density signals on host-parasite interactions.

Science.gov (United States)

Michel, Jessica; Ebert, Dieter; Hall, Matthew D

2016-11-25

The density of a host population is a key parameter underlying disease transmission, but it also has implications for the expression of disease through its effect on host physiology. In response to higher densities, individuals are predicted to either increase their immune investment in response to the elevated risk of parasitism, or conversely to decrease their immune capacity as a consequence of the stress of a crowded environment. However, an individual's health is shaped by many different factors, including their genetic background, current environmental conditions, and maternal effects. Indeed, population density is often sensed through the presence of info-chemicals in the environment, which may influence a host's interaction with parasites, and also those of its offspring. All of which may alter the expression of disease, and potentially uncouple the presumed link between changes in host density and disease outcomes. In this study, we used the water flea Daphnia magna and its obligate bacterial parasite Pasteuria ramosa, to investigate how signals of high host density impact on host-parasite interactions over two consecutive generations. We found that the chemical signals from crowded treatments induced phenotypic changes in both the parental and offspring generations. In the absence of a pathogen, life-history changes were genotype-specific, but consistent across generations, even when the signal of density was removed. In contrast, the influence of density on infected animals depended on the trait and generation of exposure. When directly exposed to signals of high-density, host genotypes responded differently in how they minimised the severity of disease. Yet, in the subsequent generation, the influence of density was rarely genotype-specific and instead related to ability of the host to minimise the onset of infection. Our findings reveal that population level correlations between host density and infection capture only part of the complex relationship

An experimental field study of delayed density dependence in natural populations of Aedes albopictus.

Directory of Open Access Journals (Sweden)

Rachael K Walsh

Full Text Available Aedes albopictus, a species known to transmit dengue and chikungunya viruses, is primarily a container-inhabiting mosquito. The potential for pathogen transmission by Ae. albopictus has increased our need to understand its ecology and population dynamics. Two parameters that we know little about are the impact of direct density-dependence and delayed density-dependence in the larval stage. The present study uses a manipulative experimental design, under field conditions, to understand the impact of delayed density dependence in a natural population of Ae. albopictus in Raleigh, North Carolina. Twenty liter buckets, divided in half prior to experimentation, placed in the field accumulated rainwater and detritus, providing oviposition and larval production sites for natural populations of Ae. albopictus. Two treatments, a larvae present and larvae absent treatment, were produced in each bucket. After five weeks all larvae were removed from both treatments and the buckets were covered with fine mesh cloth. Equal numbers of first instars were added to both treatments in every bucket. Pupae were collected daily and adults were frozen as they emerged. We found a significant impact of delayed density-dependence on larval survival, development time and adult body size in containers with high larval densities. Our results indicate that delayed density-dependence will have negative impacts on the mosquito population when larval densities are high enough to deplete accessible nutrients faster than the rate of natural food accumulation.

Effects of population density on agricultural land use and ...

African Journals Online (AJOL)

This study examined agricultural land use and productivity with particular reference to its effects on population density in the Nsukka Agricultural Zone of Enugu State, Nigeria. The study involved distribution of questionnaires to 96 respondents, with only 60 being valid. Majority of the respondents had farms of between one ...

The influence of population density and duration of breeding on ...

African Journals Online (AJOL)

The influence of population density and duration of breeding on broiler chickens productivity and profitability. S Mitrovic, V Dermanovi c, M Radivojevi c, Z Raji c, D Živkovi c, D Ostoji c, N Filipovi c ...

Whitebark pine, population density, and home-range size of grizzly bears in the greater yellowstone ecosystem.

Directory of Open Access Journals (Sweden)

Daniel D Bjornlie

Full Text Available Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos in the Greater Yellowstone Ecosystem (GYE, recent decline of whitebark pine (WBP; Pinus albicaulis, an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

Whitebark pine, population density, and home-range size of grizzly bears in the greater Yellowstone ecosystem

Science.gov (United States)

Bjornlie, Daniel D.; van Manen, Frank T.; Ebinger, Michael R.; Haroldson, Mark A.; Thompson, Daniel J.; Costello, Cecily M.

2014-01-01

Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE), recent decline of whitebark pine (WBP; Pinus albicaulis), an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

Whitebark pine, population density, and home-range size of grizzly bears in the greater yellowstone ecosystem.

Science.gov (United States)

Bjornlie, Daniel D; Van Manen, Frank T; Ebinger, Michael R; Haroldson, Mark A; Thompson, Daniel J; Costello, Cecily M

2014-01-01

Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE), recent decline of whitebark pine (WBP; Pinus albicaulis), an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

Consequences for conservation: population density and genetic effects on reproduction of an endangered lagomorph.

Science.gov (United States)

Demay, Stephanie M; Becker, Penny A; Waits, Lisette P; Johnson, Timothy R; Rachlow, Janet L

2016-04-01

Understanding reproduction and mating systems is important for managers tasked with conserving vulnerable species. Genetic tools allow biologists to investigate reproduction and mating systems with high resolution and are particularly useful for species that are otherwise difficult to study in their natural environments. We conducted parentage analyses using 19 nuclear DNA microsatellite loci to assess the influence of population density, genetic diversity, and ancestry on reproduction, and to examine the mating system of pygmy rabbits (Brachylagus idahoensis) bred in large naturalized enclosures for the reintroduction and recovery of the endangered distinct population in central Washington, USA. Reproductive output for females and males decreased as population density and individual homozygosity increased. We identified an interaction indicating that male reproductive output decreased as genetic diversity declined at high population densities, but there was no effect at low densities. Males with high amounts (> 50%) of Washington ancestry had higher reproductive output than the other ancestry groups, while reproductive output was decreased for males with high northern Utah/Wyoming ancestry and females with high Oregon/Nevada ancestry. Females and males bred with an average of 3.8 and 3.6 mates per year, respectively, and we found no evidence of positive or negative assortative mating with regards to ancestry. Multiple paternity was confirmed in 81% of litters, and we report the first documented cases of juvenile breeding by pygmy rabbits. This study demonstrates how variation in population density, genetic diversity, and ancestry impact fitness for an endangered species being bred for conservation. Our results advance understanding of basic life history characteristics for a cryptic species that is difficult to study in the wild and provide lessons for managing populations of vulnerable species in captive and free-ranging populations.

Modeling the growth of individuals in plant populations: local density variation in a strand population of Xanthium strumarium (Asteraceae).

Science.gov (United States)

Weiner, J; Kinsman, S; Williams, S

1998-11-01

We studied the growth of individual Xanthium strumarium plants growing at four naturally occurring local densities on a beach in Maine: (1) isolated plants, (2) pairs of plants ≤1 cm apart, (3) four plants within 4 cm of each other, and (4) discrete dense clumps of 10-39 plants. A combination of nondestructive measurements every 2 wk and parallel calibration harvests provided very good estimates of the growth in aboveground biomass of over 400 individual plants over 8 wk and afforded the opportunity to fit explicit growth models to 293 of them. There was large individual variation in growth and resultant size within the population and within all densities. Local crowding played a role in determining plant size within the population: there were significant differences in final size between all densities except pairs and quadruples, which were almost identical. Overall, plants growing at higher densities were more variable in growth and final size than plants growing at lower densities, but this was due to increased variation among groups (greater variation in local density and/or greater environmental heterogeneity), not to increased variation within groups. Thus, there was no evidence of size asymmetric competition in this population. The growth of most plants was close to exponential over the study period, but half the plants were slightly better fit by a sigmoidal (logistic) model. The proportion of plants better fit by the logistic model increased with density and with initial plant size. The use of explicit growth models over several growth intervals to describe stand development can provide more biological content and more statistical power than "growth-size" methods that analyze growth intervals separately.

Inter cropping and population density effects on yield component ...

African Journals Online (AJOL)

Thus the objective of this study was to determine the influence of intercropping and population density on protein and oil yield components, photosynthesis of sorghum and Soybean at the canopy closure. The study was conducted at the University of Nairobi farm during the long rains. There was a significant increase in the ...

Experimental test of an eco-evolutionary dynamic feedback loop between evolution and population density in the green peach aphid.

Science.gov (United States)

Turcotte, Martin M; Reznick, David N; Daniel Hare, J

2013-05-01

An eco-evolutionary feedback loop is defined as the reciprocal impacts of ecology on evolutionary dynamics and evolution on ecological dynamics on contemporary timescales. We experimentally tested for an eco-evolutionary feedback loop in the green peach aphid, Myzus persicae, by manipulating initial densities and evolution. We found strong evidence that initial aphid density alters the rate and direction of evolution, as measured by changes in genotype frequencies through time. We also found that evolution of aphids within only 16 days, or approximately three generations, alters the rate of population growth and predicts density compared to nonevolving controls. The impact of evolution on population dynamics also depended on density. In one evolution treatment, evolution accelerated population growth by up to 10.3% at high initial density or reduced it by up to 6.4% at low initial density. The impact of evolution on population growth was as strong as or stronger than that caused by a threefold change in intraspecific density. We found that, taken together, ecological condition, here intraspecific density, alters evolutionary dynamics, which in turn alter concurrent population growth rate (ecological dynamics) in an eco-evolutionary feedback loop. Our results suggest that ignoring evolution in studies predicting population dynamics might lead us to over- or underestimate population density and that we cannot predict the evolutionary outcome within aphid populations without considering population size.

Principles of monitoring for the radiation protection of the population

International Nuclear Information System (INIS)

Sowby, F.D.

1984-01-01

In this report all exposures are considered except occupational exposure and exposure to patients from medical uses of radiation. The subject is dealt with under the following headings: explanation of terms and relevant recommendations of the I.C.R.P., interaction between modelling and monitoring, general objectives and requirements of monitoring programmes, monitoring of source, environment and individuals within the population, quality assurance. (U.K.)

Low crop plant population densities promote pollen-mediated gene flow in spring wheat (Triticum aestivum L.).

Science.gov (United States)

Willenborg, Christian J; Brûlé-Babel, Anita L; Van Acker, Rene C

2009-12-01

Transgenic wheat is currently being field tested with the intent of eventual commercialization. The development of wheat genotypes with novel traits has raised concerns regarding the presence of volunteer wheat populations and the role they may play in facilitating transgene movement. Here, we report the results of a field experiment that investigated the potential of spring wheat plant population density and crop height to minimize gene flow from a herbicide-resistant (HR) volunteer population to a non-HR crop. Pollen-mediated gene flow (PMGF) between the HR volunteer wheat population and four conventional spring wheat genotypes varying in height was assessed over a range of plant population densities. Natural hybridization events between the two cultivars were detected by phenotypically scoring plants in F(1) populations followed by verification with Mendelian segregation ratios in the F(1:2) families. PMGF was strongly associated with crop yield components, but showed no association with flowering synchrony. Maximum observed PMGF was always less than 0.6%, regardless of crop height and density. The frequency of PMGF in spring wheat decreased exponentially with increasing plant population density, but showed no dependence on either crop genotype or height. However, increasing plant densities beyond the recommended planting rate of 300 cropped wheat plants m(-2) provided no obvious benefit to reducing PMGF. Nevertheless, our results demonstrate a critical plant density of 175-200 cropped wheat plants m(-2) below which PMGF frequencies rise exponentially with decreasing plant density. These results will be useful in the development of mechanistic models and best management practices that collectively facilitate the coexistence of transgenic and nontransgenic wheat crops.

Stochastic seasonality and nonlinear density-dependent factors regulate population size in an African rodent

DEFF Research Database (Denmark)

Leirs, Herwig; Steneth, Nils Chr.; Nichols, James D.

1997-01-01

, but clear examples of both processes acting in the same population are rare(7,8). Key-factor analysis (regression of population changes on possible causal factors) and time-series analysis are often used to investigate the presence of density dependence, but such approaches may be biased and provide...... no information on actual demographic rates(9,10). Here we report on both density-dependent and density-independent effects in a murid rodent pest species, the multimammute rat Mastomys natalensis (Smith, 1834), using statistical capture-recapture models, Both effects occur simultaneously, but we also demonstrate...

Ethical issues in using Twitter for population-level depression monitoring: a qualitative study.

Science.gov (United States)

Mikal, Jude; Hurst, Samantha; Conway, Mike

2016-04-14

Recently, significant research effort has focused on using Twitter (and other social media) to investigate mental health at the population-level. While there has been influential work in developing ethical guidelines for Internet discussion forum-based research in public health, there is currently limited work focused on addressing ethical problems in Twitter-based public health research, and less still that considers these issues from users' own perspectives. In this work, we aim to investigate public attitudes towards utilizing public domain Twitter data for population-level mental health monitoring using a qualitative methodology. The study explores user perspectives in a series of five, 2-h focus group interviews. Following a semi-structured protocol, 26 Twitter users with and without a diagnosed history of depression discussed general Twitter use, along with privacy expectations, and ethical issues in using social media for health monitoring, with a particular focus on mental health monitoring. Transcripts were then transcribed, redacted, and coded using a constant comparative approach. While participants expressed a wide range of opinions, there was an overall trend towards a relatively positive view of using public domain Twitter data as a resource for population level mental health monitoring, provided that results are appropriately aggregated. Results are divided into five sections: (1) a profile of respondents' Twitter use patterns and use variability; (2) users' privacy expectations, including expectations regarding data reach and permanence; (3) attitudes towards social media based population-level health monitoring in general, and attitudes towards mental health monitoring in particular; (4) attitudes towards individual versus population-level health monitoring; and (5) users' own recommendations for the appropriate regulation of population-level mental health monitoring. Focus group data reveal a wide range of attitudes towards the use of public

Populational Growth Models Proportional to Beta Densities with Allee Effect

Science.gov (United States)

Aleixo, Sandra M.; Rocha, J. Leonel; Pestana, Dinis D.

2009-05-01

We consider populations growth models with Allee effect, proportional to beta densities with shape parameters p and 2, where the dynamical complexity is related with the Malthusian parameter r. For p>2, these models exhibit a population dynamics with natural Allee effect. However, in the case of 1

Global asymptotic stability of density dependent integral population projection models.

Science.gov (United States)

Rebarber, Richard; Tenhumberg, Brigitte; Townley, Stuart

2012-02-01

Many stage-structured density dependent populations with a continuum of stages can be naturally modeled using nonlinear integral projection models. In this paper, we study a trichotomy of global stability result for a class of density dependent systems which include a Platte thistle model. Specifically, we identify those systems parameters for which zero is globally asymptotically stable, parameters for which there is a positive asymptotically stable equilibrium, and parameters for which there is no asymptotically stable equilibrium. Copyright © 2011 Elsevier Inc. All rights reserved.

Immigration Rates during Population Density Reduction in a Coral Reef Fish

Science.gov (United States)

Turgeon, Katrine; Kramer, Donald L.

2016-01-01

Although the importance of density-dependent dispersal has been recognized in theory, few empirical studies have examined how immigration changes over a wide range of densities. In a replicated experiment using a novel approach allowing within-site comparison, we examined changes in immigration rate following the gradual removal of territorial damselfish from a limited area within a much larger patch of continuous habitat. In all sites, immigration occurred at intermediate densities but did not occur before the start of removals and only rarely as density approached zero. In the combined data and in 5 of 7 sites, the number of immigrants was a hump-shaped function of density. This is the first experimental evidence for hump-shaped, density-dependent immigration. This pattern may be more widespread than previously recognized because studies over more limited density ranges have identified positive density dependence at low densities and negative density dependence at high densities. Positive density dependence at low density can arise from limits to the number of potential immigrants and from behavioral preferences for settling near conspecifics. Negative density dependence at high density can arise from competition for resources, especially high quality territories. The potential for non-linear effects of local density on immigration needs to be recognized for robust predictions of conservation reserve function, harvest impacts, pest control, and the dynamics of fragmented populations. PMID:27271081

Evaluation of yellow sticky traps for monitoring the population of thrips (Thysanoptera) in a mango orchard.

Science.gov (United States)

Aliakbarpour, Hamaseh; Rawi, Che Salmah Md

2011-08-01

Populations of several thrips species were estimated using yellow sticky traps in an orchard planted with mango, Mangifera indica L. during the dry and wet seasons beginning in late 2008-2009 on Penang Island, Malaysia. To determine the efficacy of using sticky traps to monitor thrips populations, we compared weekly population estimates on yellow sticky traps with thrips population sizes that were determined (using a CO(2) method) directly from mango panicles. Dispersal distance and direction of thrips movement out of the orchard also were studied using yellow sticky traps placed at three distances from the edge of the orchard in four cardinal directions facing into the orchard. The number of thrips associated with the mango panicles was found to be correlated with the number of thrips collected using the sticky trap method. The number of thrips captured by the traps decreased with increasing distance from the mango orchard in all directions. Density of thrips leaving the orchard was related to the surrounding vegetation. Our results demonstrate that sticky traps have the potential to satisfactorily estimate thrips populations in mango orchards and thus they can be effectively employed as a useful tactic for sampling thrips.

Using ecology to inform physiology studies: implications of high population density in the laboratory.

Science.gov (United States)

Newman, Amy E M; Edmunds, Nicholas B; Ferraro, Shannon; Heffell, Quentin; Merritt, Gillian M; Pakkala, Jesse J; Schilling, Cory R; Schorno, Sarah

2015-03-15

Conspecific density is widely recognized as an important ecological factor across the animal kingdom; however, the physiological impacts are less thoroughly described. In fact, population density is rarely mentioned as a factor in physiological studies on captive animals and, when it is infrequently addressed, the animals used are reared and housed at densities far above those in nature, making the translation of results from the laboratory to natural systems difficult. We survey the literature to highlight this important ecophysiological gap and bring attention to the possibility that conspecific density prior to experimentation may be a critical factor influencing results. Across three taxa: mammals, birds, and fish, we present evidence from ecology that density influences glucocorticoid levels, immune function, and body condition with the intention of stimulating discussion and increasing consideration of population density in physiology studies. We conclude with several directives to improve the applicability of insights gained in the laboratory to organisms in the natural environment. Copyright © 2015 the American Physiological Society.

The impact of urbanization and population density on childhood Plasmodium falciparum parasite prevalence rates in Africa.

Science.gov (United States)

Kabaria, Caroline W; Gilbert, Marius; Noor, Abdisalan M; Snow, Robert W; Linard, Catherine

2017-01-26

Although malaria has been traditionally regarded as less of a problem in urban areas compared to neighbouring rural areas, the risk of malaria infection continues to exist in densely populated, urban areas of Africa. Despite the recognition that urbanization influences the epidemiology of malaria, there is little consensus on urbanization relevant for malaria parasite mapping. Previous studies examining the relationship between urbanization and malaria transmission have used products defining urbanization at global/continental scales developed in the early 2000s, that overestimate actual urban extents while the population estimates are over 15 years old and estimated at administrative unit level. This study sought to discriminate an urbanization definition that is most relevant for malaria parasite mapping using individual level malaria infection data obtained from nationally representative household-based surveys. Boosted regression tree (BRT) modelling was used to determine the effect of urbanization on malaria transmission and if this effect varied with urbanization definition. In addition, the most recent high resolution population distribution data was used to determine whether population density had significant effect on malaria parasite prevalence and if so, could population density replace urban classifications in modelling malaria transmission patterns. The risk of malaria infection was shown to decline from rural areas through peri-urban settlements to urban central areas. Population density was found to be an important predictor of malaria risk. The final boosted regression trees (BRT) model with urbanization and population density gave the best model fit (Tukey test p value <0.05) compared to the models with urbanization only. Given the challenges in uniformly classifying urban areas across different countries, population density provides a reliable metric to adjust for the patterns of malaria risk in densely populated urban areas. Future malaria risk

Science deficiency in conservation practice: the monitoring of tiger populations in India

Science.gov (United States)

Karanth, K.U.; Nichols, J.D.; Seidensticker, J.; Dinerstein, Eric; Smith, J.L.D.; McDougal, C.; Johnsingh, A.J.T.; Chundawat, Raghunandan S.; Thapar, V.

2003-01-01

Conservation practices are supposed to get refined by advancing scientific knowledge. We study this phenomenon in the context of monitoring tiger populations in India, by evaluating the 'pugmark census method' employed by wildlife managers for three decades. We use an analytical framework of modem animal population sampling to test the efficacy of the pugmark censuses using scientific data on tigers and our field observations. We identify three critical goals for monitoring tiger populations, in order of increasing sophistication: (1) distribution mapping, (2) tracking relative abundance, (3) estimation of absolute abundance. We demonstrate that the present census-based paradigm does not work because it ignores the first two simpler goals, and targets, but fails to achieve, the most difficult third goal. We point out the utility and ready availability of alternative monitoring paradigms that deal with the central problems of spatial sampling and observability. We propose an alternative sampling-based approach that can be tailored to meet practical needs of tiger monitoring at different levels of refinement.

Groundwater resources monitoring and population displacement in northern Uganda

Science.gov (United States)

Chalikakis, K.; Hammache, Y.; Nawa, A.; Slinski, K.; Petropoulos, G.; Muteesasira, A.

2009-04-01

provide a guideline for a sustainable exploration of groundwater resources within the investigated regions, relating to population movements and potential of aquifers. To achieve these objectives a) groundwater samples are collected and analyzed (microbiologically, chemically and physically) from all types of water points, boreholes and "protected" springs, during rainy, dry and intermediate seasons, b) a network of piezometers is being installed for monitoring groundwater level, and comparison with available rainfall data will define groundwater balance. During these steps results are compared with the population's displacement and density in order to quantify the consequences towards the groundwater resources. Preliminary results after microbiological analysis show the inadequacy of traditional "protected" springs in providing safe water. Feacal pollution is observed in "protected" springs even though it was not being observed before and during rehabilitation. It is mainly due to recent population concentration around the available water resources and the lack of comprehensive hydrogeological study of the functioning of the near surface aquifers. Accordingly all operations concerning spring rehabilitation are on hold. No evidence regarding microbiological contamination was found from borehole water samples. However, high concentration in ferrous iron and total iron was found in several boreholes. Concentrations in the water of weathered bedrock are expected and specific treatment is necessary.

Monitoring, imperfect detection, and risk optimization of a Tasmanian devil insurance population.

Science.gov (United States)

Rout, Tracy M; Baker, Christopher M; Huxtable, Stewart; Wintle, Brendan A

2018-04-01

Most species are imperfectly detected during biological surveys, which creates uncertainty around their abundance or presence at a given location. Decision makers managing threatened or pest species are regularly faced with this uncertainty. Wildlife diseases can drive species to extinction; thus, managing species with disease is an important part of conservation. Devil facial tumor disease (DFTD) is one such disease that led to the listing of the Tasmanian devil (Sarcophilus harrisii) as endangered. Managers aim to maintain devils in the wild by establishing disease-free insurance populations at isolated sites. Often a resident DFTD-affected population must first be removed. In a successful collaboration between decision scientists and wildlife managers, we used an accessible population model to inform monitoring decisions and facilitate the establishment of an insurance population of devils on Forestier Peninsula. We used a Bayesian catch-effort model to estimate population size of a diseased population from removal and camera trap data. We also analyzed the costs and benefits of declaring the area disease-free prior to reintroduction and establishment of a healthy insurance population. After the monitoring session in May-June 2015, the probability that all devils had been successfully removed was close to 1, even when we accounted for a possible introduction of a devil to the site. Given this high probability and the baseline cost of declaring population absence prematurely, we found it was not cost-effective to carry out any additional monitoring before introducing the insurance population. Considering these results within the broader context of Tasmanian devil management, managers ultimately decided to implement an additional monitoring session before the introduction. This was a conservative decision that accounted for uncertainty in model estimates and for the broader nonmonetary costs of mistakenly declaring the area disease-free. © 2017 Society for

Population Variation in the Life History of a Land Fish, Alticus arnoldorum, and the Effects of Predation and Density.

Directory of Open Access Journals (Sweden)

Edward R M Platt

Full Text Available Life history variation can often reflect differences in age-specific mortality within populations, with the general expectation that reproduction should be shifted away from ages experiencing increased mortality. Investigators of life history in vertebrates frequently focus on the impact of predation, but there is increasing evidence that predation may have unexpected impacts on population density that in turn prompt unexpected changes in life history. There are also other reasons why density might impact life history independently of predation or mortality more generally. We investigated the consequences of predation and density on life history variation among populations of the Pacific leaping blenny, Alticus arnoldorum. This fish from the island of Guam spends its adult life out of the water on rocks in the splash zone, where it is vulnerable to predation and can be expected to be sensitive to changes in population density that impact resource availability. We found populations invested more in reproduction as predation decreased, while growth rate varied primarily in response to population density. These differences in life history among populations are likely plastic given the extensive gene flow among populations revealed by a previous study. The influence of predation and density on life history was unlikely to have operated independently of each other, with predation rate tending to be associated with reduced population densities. Taken together, our results suggest predation and density can have complex influences on life history, and that plastic life history traits could allow populations to persist in new or rapidly changing environments.

Population densities of indigenous Acidobacteria change in the presence of plant growth promoting rhizobacteria (PGPR) in rhizosphere.

Science.gov (United States)

Kalam, Sadaf; Das, Subha Narayan; Basu, Anirban; Podile, Appa Rao

2017-05-01

Rhizosphere microbial community has diverse metabolic capabilities and plays a crucial role in maintaining plant health. Oligotrophic plant growth promoting rhizobacteria (PGPR), along with difficult-to-culture microbial fractions, might be involved synergistically in microbe-microbe and plant-microbe interactions in the rhizosphere. Among the difficult-to-culture microbial fractions, Acidobacteria constitutes the most dominant phylum thriving in rhizospheric soils. We selected effective PGPR for tomato and black gram and studied their effect on population densities of acidobacterial members. Three facultatively oligotrophic PGPR were identified through 16S rRNA gene sequencing as Sphingobacterium sp. (P3), Variovorax sp. (P4), and Roseomonas sp. (A2); the latter being a new report of PGPR. In presence of selected PGPR strains, the changes in population densities of Acidobacteria were monitored in metagenomic DNA extracted from bulk and rhizospheric soils of tomato and black gram using real time qPCR. A gradual increase in equivalent cell numbers of Acidobacteria members was observed over time along with a simultaneous increase in plant growth promotion by test PGPR. We report characterization of three effective PGPR strains and their effects on indigenous, underexplored difficult-to-culture phylum-Acidobacteria. We suggest that putative interactions between these two bacterial groups thriving in rhizospheric soils could be beneficial for plant growth. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DNA-based population density estimation of black bear at northern ...

African Journals Online (AJOL)

The analysis of deoxyribonucleic acid (DNA) microsatellites from hair samples obtained by the non-invasive method of traps was used to estimate the population density of black bears (Ursus americanus eremicus) in a mountain located at the county of Lampazos, Nuevo Leon, Mexico. The genotyping of bears was ...

Linking individual phenotype to density-dependent population growth: the influence of body size on the population dynamics of malaria vectors

NARCIS (Netherlands)

Russell, T.L.; Lwetoijera, D.W.; Knols, B.G.J.; Takken, W.; Killeen, G.F.; Ferguson, H.M.

2011-01-01

Understanding the endogenous factors that drive the population dynamics of malaria mosquitoes will facilitate more accurate predictions about vector control effectiveness and our ability to destabilize the growth of either low- or high-density insect populations. We assessed whether variation in

Linking individual phenotype to density-dependent population growth: the influence of body size on the population dynamics of malaria vectors

NARCIS (Netherlands)

Russell, T.L.; Lwetoijera, D.W.; Knols, B.G.J.; Takken, W.; Killeen, G.F.; Ferguson, H.M.

2011-01-01

Understanding the endogenous factors that drive the population dynamics of malaria mosquitoes will facilitate more accurate predictions about vector control effectiveness and our ability to destabilize the growth of either low-or high-density insect populations. We assessed whether variation in

Identification of the population density of a species model with nonlocal diffusion and nonlinear reaction

Science.gov (United States)

Tuan, Nguyen Huy; Van Au, Vo; Khoa, Vo Anh; Lesnic, Daniel

2017-05-01

The identification of the population density of a logistic equation backwards in time associated with nonlocal diffusion and nonlinear reaction, motivated by biology and ecology fields, is investigated. The diffusion depends on an integral average of the population density whilst the reaction term is a global or local Lipschitz function of the population density. After discussing the ill-posedness of the problem, we apply the quasi-reversibility method to construct stable approximation problems. It is shown that the regularized solutions stemming from such method not only depend continuously on the final data, but also strongly converge to the exact solution in L 2-norm. New error estimates together with stability results are obtained. Furthermore, numerical examples are provided to illustrate the theoretical results.

Estimating population density and connectivity of American mink using spatial capture-recapture.

Science.gov (United States)

Fuller, Angela K; Sutherland, Chris S; Royle, J Andrew; Hare, Matthew P

2016-06-01

Estimating the abundance or density of populations is fundamental to the conservation and management of species, and as landscapes become more fragmented, maintaining landscape connectivity has become one of the most important challenges for biodiversity conservation. Yet these two issues have never been formally integrated together in a model that simultaneously models abundance while accounting for connectivity of a landscape. We demonstrate an application of using capture-recapture to develop a model of animal density using a least-cost path model for individual encounter probability that accounts for non-Euclidean connectivity in a highly structured network. We utilized scat detection dogs (Canis lupus familiaris) as a means of collecting non-invasive genetic samples of American mink (Neovison vison) individuals and used spatial capture-recapture models (SCR) to gain inferences about mink population density and connectivity. Density of mink was not constant across the landscape, but rather increased with increasing distance from city, town, or village centers, and mink activity was associated with water. The SCR model allowed us to estimate the density and spatial distribution of individuals across a 388 km² area. The model was used to investigate patterns of space usage and to evaluate covariate effects on encounter probabilities, including differences between sexes. This study provides an application of capture-recapture models based on ecological distance, allowing us to directly estimate landscape connectivity. This approach should be widely applicable to provide simultaneous direct estimates of density, space usage, and landscape connectivity for many species.

Estimating population density and connectivity of American mink using spatial capture-recapture

Science.gov (United States)

Fuller, Angela K.; Sutherland, Christopher S.; Royle, Andy; Hare, Matthew P.

2016-01-01

Estimating the abundance or density of populations is fundamental to the conservation and management of species, and as landscapes become more fragmented, maintaining landscape connectivity has become one of the most important challenges for biodiversity conservation. Yet these two issues have never been formally integrated together in a model that simultaneously models abundance while accounting for connectivity of a landscape. We demonstrate an application of using capture–recapture to develop a model of animal density using a least-cost path model for individual encounter probability that accounts for non-Euclidean connectivity in a highly structured network. We utilized scat detection dogs (Canis lupus familiaris) as a means of collecting non-invasive genetic samples of American mink (Neovison vison) individuals and used spatial capture–recapture models (SCR) to gain inferences about mink population density and connectivity. Density of mink was not constant across the landscape, but rather increased with increasing distance from city, town, or village centers, and mink activity was associated with water. The SCR model allowed us to estimate the density and spatial distribution of individuals across a 388 km2 area. The model was used to investigate patterns of space usage and to evaluate covariate effects on encounter probabilities, including differences between sexes. This study provides an application of capture–recapture models based on ecological distance, allowing us to directly estimate landscape connectivity. This approach should be widely applicable to provide simultaneous direct estimates of density, space usage, and landscape connectivity for many species.

Long-term monitoring of an insular population of Barbary Falcon ...

African Journals Online (AJOL)

Territory spacing and breeding rates of an insular population (north-western Tenerife, Canary Islands) of Barbary Falcon Falco peregrinus pelegrinoides was studied from 1993 to 2008. The population increased constantly since the outset, from two pairs in 1993 to 12 in 2008. Mean density was 5.48 pairs per 100 km2 and ...

The non-linear, interactive effects of population density and climate drive the geographical patterns of waterfowl survival

Science.gov (United States)

Zhao, Qing; Boomer, G. Scott; Kendall, William L.

2018-01-01

On-going climate change has major impacts on ecological processes and patterns. Understanding the impacts of climate on the geographical patterns of survival can provide insights to how population dynamics respond to climate change and provide important information for the development of appropriate conservation strategies at regional scales. It is challenging to understand the impacts of climate on survival, however, due to the fact that the non-linear relationship between survival and climate can be modified by density-dependent processes. In this study we extended the Brownie model to partition hunting and non-hunting mortalities and linked non-hunting survival to covariates. We applied this model to four decades (1972–2014) of waterfowl band-recovery, breeding population survey, and precipitation and temperature data covering multiple ecological regions to examine the non-linear, interactive effects of population density and climate on waterfowl non-hunting survival at a regional scale. Our results showed that the non-linear effect of temperature on waterfowl non-hunting survival was modified by breeding population density. The concave relationship between non-hunting survival and temperature suggested that the effects of warming on waterfowl survival might be multifaceted. Furthermore, the relationship between non-hunting survival and temperature was stronger when population density was higher, suggesting that high-density populations may be less buffered against warming than low-density populations. Our study revealed distinct relationships between waterfowl non-hunting survival and climate across and within ecological regions, highlighting the importance of considering different conservation strategies according to region-specific population and climate conditions. Our findings and associated novel modelling approach have wide implications in conservation practice.

Large-scale control site selection for population monitoring: an example assessing Sage-grouse trends

Science.gov (United States)

Fedy, Bradley C.; O'Donnell, Michael; Bowen, Zachary H.

2015-01-01

Human impacts on wildlife populations are widespread and prolific and understanding wildlife responses to human impacts is a fundamental component of wildlife management. The first step to understanding wildlife responses is the documentation of changes in wildlife population parameters, such as population size. Meaningful assessment of population changes in potentially impacted sites requires the establishment of monitoring at similar, nonimpacted, control sites. However, it is often difficult to identify appropriate control sites in wildlife populations. We demonstrated use of Geographic Information System (GIS) data across large spatial scales to select biologically relevant control sites for population monitoring. Greater sage-grouse (Centrocercus urophasianus; hearafter, sage-grouse) are negatively affected by energy development, and monitoring of sage-grouse population within energy development areas is necessary to detect population-level responses. Weused population data (1995–2012) from an energy development area in Wyoming, USA, the Atlantic Rim Project Area (ARPA), and GIS data to identify control sites that were not impacted by energy development for population monitoring. Control sites were surrounded by similar habitat and were within similar climate areas to the ARPA. We developed nonlinear trend models for both the ARPA and control sites and compared long-term trends from the 2 areas. We found little difference between the ARPA and control sites trends over time. This research demonstrated an approach for control site selection across large landscapes and can be used as a template for similar impact-monitoring studies. It is important to note that identification of changes in population parameters between control and treatment sites is only the first step in understanding the mechanisms that underlie those changes. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Dietary Energy Density in the Australian Adult Population from National Nutrition Surveys 1995 to 2012.

Science.gov (United States)

Grech, Amanda Lee; Rangan, Anna; Allman-Farinelli, Margaret

2017-12-01

It is hypothesized that the observed proliferation of energy-dense, nutrient-poor foods globally is an important contributing factor to the development of the obesity epidemic. However, evidence that the population's dietary energy density has increased is sparse. The World Cancer Research Fund recommends that dietary energy density be density of the Australian population has changed between 1995 and 2012. A secondary analysis of two cross-sectional Australian national nutrition surveys from 1995 and 2011/2012 was conducted. Participants of the surveys included adults aged 18 years and older (1995 n=10,986 and 2011/2012 n=9,435) completing 24-hour dietary recalls, including a second recall for a subset of the population (10.4% in 1995 and 64.6% in 2011/2012). Outcome measures included the change in dietary energy density (calculated as energy/weight of food [kcal/g] for food only) between surveys. The National Cancer Institute method for "estimating ratios of two dietary components that are consumed nearly every day" was used to determine the usual distribution and the percentage of participants reporting energy density density was 1.59 (0.26) kcal/g and 1.64 (0.32) kcal/g (Pdensity recommendations. For those aged 70 years and older, the percentage with energy density density density has increased between the two surveys and few people consumed low energy-dense diets in line with recommendations. The change was largely due to increased energy density of older adult's diets, while young adults had high dietary energy density at both time points. These data suggest efforts now focus on the evaluation of the role of modifying energy density of the diet to reduce the risk of weight gain in adults. Copyright © 2017 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

A new approach on seismic mortality estimations based on average population density

Science.gov (United States)

Zhu, Xiaoxin; Sun, Baiqing; Jin, Zhanyong

2016-12-01

This study examines a new methodology to predict the final seismic mortality from earthquakes in China. Most studies established the association between mortality estimation and seismic intensity without considering the population density. In China, however, the data are not always available, especially when it comes to the very urgent relief situation in the disaster. And the population density varies greatly from region to region. This motivates the development of empirical models that use historical death data to provide the path to analyze the death tolls for earthquakes. The present paper employs the average population density to predict the final death tolls in earthquakes using a case-based reasoning model from realistic perspective. To validate the forecasting results, historical data from 18 large-scale earthquakes occurred in China are used to estimate the seismic morality of each case. And a typical earthquake case occurred in the northwest of Sichuan Province is employed to demonstrate the estimation of final death toll. The strength of this paper is that it provides scientific methods with overall forecast errors lower than 20 %, and opens the door for conducting final death forecasts with a qualitative and quantitative approach. Limitations and future research are also analyzed and discussed in the conclusion.

The role of population density on the impact of urbaniza-tion on GHG emissions in China

Science.gov (United States)

Liu, Yonghong; Gao, Chaochao; Lu, Yingying

2017-04-01

Urbanization directly drives rural to urban population migration and indirectly causes west to east migration in China, two phenomena that may significantly impact China's greenhouse gas emissions given its huge population and vast difference between the western rural and eastern urban areas. These two phenomena were analyzed by using emissions as a per capita term, and extending the impact from the traditional urbanization rate effect to include population density effect. The results show that population density has actually been the dominant demographic player in changing per capita emissions for the past two decades in China, and its elasticity changed from positive in economically less-developed provinces to negative for the developed provinces. This study provides a new perspective in the study of the relationship between urbanization and greenhouse gas emissions, and the results indicate that population density change should be taken into account to accurately assess the impact of urbanization.

A synthesis of European seahorse taxonomy, population structure, and habitat use as a basis for assessment, monitoring and conservation.

Science.gov (United States)

Woodall, Lucy C; Otero-Ferrer, Francisco; Correia, Miguel; Curtis, Janelle M R; Garrick-Maidment, Neil; Shaw, Paul W; Koldewey, Heather J

2018-01-01

Accurate taxonomy, population demography, and habitat descriptors inform species threat assessments and the design of effective conservation measures. Here we combine published studies with new genetic, morphological and habitat data that were collected from seahorse populations located along the European and North African coastlines to help inform management decisions for European seahorses. This study confirms the presence of only two native seahorse species ( Hippocampus guttulatus and H. hippocampus ) across Europe, with sporadic occurrence of non-native seahorse species in European waters. For the two native species, our findings demonstrate that highly variable morphological characteristics, such as size and presence or number of cirri, are unreliable for distinguishing species. Both species exhibit sex dimorphism with females being significantly larger. Across its range, H. guttulatus were larger and found at higher densities in cooler waters, and individuals in the Black Sea were significantly smaller than in other populations. H. hippocampus were significantly larger in Senegal. Hippocampus guttulatus tends to have higher density populations than H. hippocampus when they occur sympatrically. Although these species are often associated with seagrass beds, data show both species inhabit a wide variety of shallow habitats and use a mixture of holdfasts. We suggest an international mosaic of protected areas focused on multiple habitat types as the first step to successful assessment, monitoring and conservation management of these Data Deficient species.

Population density and efficiency in energy consumption: An empirical analysis of service establishments

International Nuclear Information System (INIS)

Morikawa, Masayuki

2012-01-01

This study, using novel establishment-level microdata from the Energy Consumption Statistics, empirically analyzes the effect of urban density on energy intensity in the service sector. According to the analysis, the efficiency of energy consumption in service establishments is higher for densely populated cities. Quantitatively, after controlling for differences among industries, energy efficiency increases by approximately 12% when the density in a municipality population doubles. This result suggests that, given a structural transformation toward the service economy, deregulation of excessive restrictions hindering urban agglomeration, and investment in infrastructure in city centers would contribute to environmentally friendly economic growth.

Conservation implications of brown hyaena (Parahyaena brunnea population densities and distribution across landscapes in Botswana

Directory of Open Access Journals (Sweden)

Christiaan W. Winterbach

2017-05-01

Full Text Available The brown hyaena (Parahyaena brunnea is endemic to southern Africa. The largest population of this near-threatened species occurs in Botswana, but limited data were available to assess distribution and density. Our objectives were to use a stratified approach to collate available data and to collect more data to assess brown hyaena distribution and density across land uses in Botswana. We conducted surveys using track counts, camera traps and questionnaires and collated our results and available data to estimate the brown hyaena population based on the stratification of Botswana for large carnivores. Brown hyaenas occur over 533 050 km² (92% of Botswana. Our density estimates ranged from 0 brown hyaenas/100 km² in strata of northern Botswana to 2.94 (2.16–3.71 brown hyaenas/100 km² in the southern stratum of the Central Kalahari Game Reserve. We made assumptions regarding densities in strata that lacked data, using the best references available. We estimated the brown hyaena population in Botswana as 4642 (3133–5993 animals, with 6.8% of the population in the Northern Conservation Zone, 73.1% in the Southern Conservation Zone, 2.0% in the smaller conservation zones and 18.1% in the agricultural zones. The similar densities of brown hyaenas in the Central Kalahari Game Reserve and the Ghanzi farms highlight the potential of agricultural areas in Botswana to conserve this species. The conservation of brown hyaenas in the agricultural landscape of Botswana is critical for the long-term conservation of the species; these areas provide important links between populations in South Africa, Namibia and Zimbabwe. Conservation implications: Botswana contains the core of the brown hyaena population in southern Africa, and conflict mitigation on agricultural land is crucial to maintaining connectivity among the range countries.

Long-Term Bird Assemblage Trends in Areas of High and Low Human Population Density

International Nuclear Information System (INIS)

Barrett, K.; Romagosa, C.M.; Williams, M.I.

2008-01-01

Urban areas are expanding globally, and the impact of high human population density (HHPD) on bird species richness remains unresolved. Studies primarily focus on species richness along an urban-to-rural gradient; however, some studies have analyzed larger-scale patterns and found results that contrast with those obtained at smaller scales. To move the discussion beyond static species richness patterns, we analyzed the effect of HHPD on bird assemblage dynamics (year-to-year extinction probability, turnover, changes in species richness) across the United States over a 25-year period. We found that bird assemblages in both high and low human population density areas changed significantly over the period of record. Specifically, bird assemblages increased in species richness on average. Assemblage change in areas of HHPD was not significantly different from assemblage change in areas with LHPD. These results suggest that human population density alone does not alter the persistence of avian assemblage patterns.

Remote sensing and spatial statistical techniques for modelling Ommatissus lybicus (Hemiptera: Tropiduchidae) habitat and population densities.

Science.gov (United States)

Al-Kindi, Khalifa M; Kwan, Paul; R Andrew, Nigel; Welch, Mitchell

2017-01-01

In order to understand the distribution and prevalence of Ommatissus lybicus (Hemiptera: Tropiduchidae) as well as analyse their current biographical patterns and predict their future spread, comprehensive and detailed information on the environmental, climatic, and agricultural practices are essential. The spatial analytical techniques such as Remote Sensing and Spatial Statistics Tools, can help detect and model spatial links and correlations between the presence, absence and density of O. lybicus in response to climatic, environmental, and human factors. The main objective of this paper is to review remote sensing and relevant analytical techniques that can be applied in mapping and modelling the habitat and population density of O. lybicus . An exhaustive search of related literature revealed that there are very limited studies linking location-based infestation levels of pests like the O. lybicus with climatic, environmental, and human practice related variables. This review also highlights the accumulated knowledge and addresses the gaps in this area of research. Furthermore, it makes recommendations for future studies, and gives suggestions on monitoring and surveillance methods in designing both local and regional level integrated pest management strategies of palm tree and other affected cultivated crops.

Remote sensing and spatial statistical techniques for modelling Ommatissus lybicus (Hemiptera: Tropiduchidae habitat and population densities

Directory of Open Access Journals (Sweden)

Khalifa M. Al-Kindi

2017-08-01

Full Text Available In order to understand the distribution and prevalence of Ommatissus lybicus (Hemiptera: Tropiduchidae as well as analyse their current biographical patterns and predict their future spread, comprehensive and detailed information on the environmental, climatic, and agricultural practices are essential. The spatial analytical techniques such as Remote Sensing and Spatial Statistics Tools, can help detect and model spatial links and correlations between the presence, absence and density of O. lybicus in response to climatic, environmental, and human factors. The main objective of this paper is to review remote sensing and relevant analytical techniques that can be applied in mapping and modelling the habitat and population density of O. lybicus. An exhaustive search of related literature revealed that there are very limited studies linking location-based infestation levels of pests like the O. lybicus with climatic, environmental, and human practice related variables. This review also highlights the accumulated knowledge and addresses the gaps in this area of research. Furthermore, it makes recommendations for future studies, and gives suggestions on monitoring and surveillance methods in designing both local and regional level integrated pest management strategies of palm tree and other affected cultivated crops.

Population density, water supply, and the risk of dengue fever in Vietnam: cohort study and spatial analysis.

Science.gov (United States)

Schmidt, Wolf-Peter; Suzuki, Motoi; Thiem, Vu Dinh; White, Richard G; Tsuzuki, Ataru; Yoshida, Lay-Myint; Yanai, Hideki; Haque, Ubydul; Tho, Le Huu; Anh, Dang Duc; Ariyoshi, Koya

2011-08-01

Aedes aegypti, the major vector of dengue viruses, often breeds in water storage containers used by households without tap water supply, and occurs in high numbers even in dense urban areas. We analysed the interaction between human population density and lack of tap water as a cause of dengue fever outbreaks with the aim of identifying geographic areas at highest risk. We conducted an individual-level cohort study in a population of 75,000 geo-referenced households in Vietnam over the course of two epidemics, on the basis of dengue hospital admissions (n = 3,013). We applied space-time scan statistics and mathematical models to confirm the findings. We identified a surprisingly narrow range of critical human population densities between around 3,000 to 7,000 people/km² prone to dengue outbreaks. In the study area, this population density was typical of villages and some peri-urban areas. Scan statistics showed that areas with a high population density or adequate water supply did not experience severe outbreaks. The risk of dengue was higher in rural than in urban areas, largely explained by lack of piped water supply, and in human population densities more often falling within the critical range. Mathematical modeling suggests that simple assumptions regarding area-level vector/host ratios may explain the occurrence of outbreaks. Rural areas may contribute at least as much to the dissemination of dengue fever as cities. Improving water supply and vector control in areas with a human population density critical for dengue transmission could increase the efficiency of control efforts. Please see later in the article for the Editors' Summary.

Population density, water supply, and the risk of dengue fever in Vietnam: cohort study and spatial analysis.

Directory of Open Access Journals (Sweden)

Wolf-Peter Schmidt

2011-08-01

Full Text Available Aedes aegypti, the major vector of dengue viruses, often breeds in water storage containers used by households without tap water supply, and occurs in high numbers even in dense urban areas. We analysed the interaction between human population density and lack of tap water as a cause of dengue fever outbreaks with the aim of identifying geographic areas at highest risk.We conducted an individual-level cohort study in a population of 75,000 geo-referenced households in Vietnam over the course of two epidemics, on the basis of dengue hospital admissions (n = 3,013. We applied space-time scan statistics and mathematical models to confirm the findings. We identified a surprisingly narrow range of critical human population densities between around 3,000 to 7,000 people/km² prone to dengue outbreaks. In the study area, this population density was typical of villages and some peri-urban areas. Scan statistics showed that areas with a high population density or adequate water supply did not experience severe outbreaks. The risk of dengue was higher in rural than in urban areas, largely explained by lack of piped water supply, and in human population densities more often falling within the critical range. Mathematical modeling suggests that simple assumptions regarding area-level vector/host ratios may explain the occurrence of outbreaks.Rural areas may contribute at least as much to the dissemination of dengue fever as cities. Improving water supply and vector control in areas with a human population density critical for dengue transmission could increase the efficiency of control efforts. Please see later in the article for the Editors' Summary.

Examining the occupancy–density relationship for a low-density carnivore

Science.gov (United States)

Linden, Daniel W.; Fuller, Angela K.; Royle, J. Andrew; Hare, Matthew P.

2017-01-01

-mixed forest and negatively associated with road density. As a result, spatially explicit management recommendations for fisher were similar across models, though relative variation was dampened for the detection–non-detection data.Synthesis and applications. Our work provides empirical evidence that models using detection–non-detection data can make similar inferences regarding relative spatial variation of the focal population to models using more expensive individual encounters when the selected spatial grain approximates or is marginally smaller than home range size. When occupancy alone is chosen as a cost-effective state variable for monitoring, simulation and sensitivity analyses should be used to understand how inferences from detection–non-detection data will be affected by aspects of study design and species ecology.

Correlations of Rotylenchulus reniformis Population Densities with 1,3-Dichloropropene Dosage Rate and Pineapple Yields

OpenAIRE

Schenck, Susan

1990-01-01

The relationships between Rotylenchulus reniformis population densities and pineapple growth and yield were studied in a small-plot field experiment. Increasing rates of handgun-injected 1,3-dichloropropene (1,3-D) preplant fumigant from 0 to 337 liters/ha resulted in greater nematode control, faster plant growth, and larger pineapple fruits. Rotylenchulus reniformis population densities at 2, 4, 6, and 8 months postplant were correlated with plant size and yield. The shorter the time period ...

Overview of national bird population monitoring programs and databases

Science.gov (United States)

Gregory S. Butcher; Bruce Peterjohn; C. John Ralph

1993-01-01

A number of programs have been set up to monitor populations of nongame migratory birds. We review these programs and their purposes and provide information on obtaining data or results from these programs. In addition, we review recommendations for improving these programs.

Relationships between population density, fine-scale genetic structure, mating system and pollen dispersal in a timber tree from African rainforests.

Science.gov (United States)

Duminil, J; Daïnou, K; Kaviriri, D K; Gillet, P; Loo, J; Doucet, J-L; Hardy, O J

2016-03-01

Owing to the reduction of population density and/or the environmental changes it induces, selective logging could affect the demography, reproductive biology and evolutionary potential of forest trees. This is particularly relevant in tropical forests where natural population densities can be low and isolated trees may be subject to outcross pollen limitation and/or produce low-quality selfed seeds that exhibit inbreeding depression. Comparing reproductive biology processes and genetic diversity of populations at different densities can provide indirect evidence of the potential impacts of logging. Here, we analysed patterns of genetic diversity, mating system and gene flow in three Central African populations of the self-compatible legume timber species Erythrophleum suaveolens with contrasting densities (0.11, 0.68 and 1.72 adults per ha). The comparison of inbreeding levels among cohorts suggests that selfing is detrimental as inbred individuals are eliminated between seedling and adult stages. Levels of genetic diversity, selfing rates (∼16%) and patterns of spatial genetic structure (Sp ∼0.006) were similar in all three populations. However, the extent of gene dispersal differed markedly among populations: the average distance of pollen dispersal increased with decreasing density (from 200 m in the high-density population to 1000 m in the low-density one). Overall, our results suggest that the reproductive biology and genetic diversity of the species are not affected by current logging practices. However, further investigations need to be conducted in low-density populations to evaluate (1) whether pollen limitation may reduce seed production and (2) the regeneration potential of the species.

Relationships between population density, fine-scale genetic structure, mating system and pollen dispersal in a timber tree from African rainforests

Science.gov (United States)

Duminil, J; Daïnou, K; Kaviriri, D K; Gillet, P; Loo, J; Doucet, J-L; Hardy, O J

2016-01-01

Owing to the reduction of population density and/or the environmental changes it induces, selective logging could affect the demography, reproductive biology and evolutionary potential of forest trees. This is particularly relevant in tropical forests where natural population densities can be low and isolated trees may be subject to outcross pollen limitation and/or produce low-quality selfed seeds that exhibit inbreeding depression. Comparing reproductive biology processes and genetic diversity of populations at different densities can provide indirect evidence of the potential impacts of logging. Here, we analysed patterns of genetic diversity, mating system and gene flow in three Central African populations of the self-compatible legume timber species Erythrophleum suaveolens with contrasting densities (0.11, 0.68 and 1.72 adults per ha). The comparison of inbreeding levels among cohorts suggests that selfing is detrimental as inbred individuals are eliminated between seedling and adult stages. Levels of genetic diversity, selfing rates (∼16%) and patterns of spatial genetic structure (Sp ∼0.006) were similar in all three populations. However, the extent of gene dispersal differed markedly among populations: the average distance of pollen dispersal increased with decreasing density (from 200 m in the high-density population to 1000 m in the low-density one). Overall, our results suggest that the reproductive biology and genetic diversity of the species are not affected by current logging practices. However, further investigations need to be conducted in low-density populations to evaluate (1) whether pollen limitation may reduce seed production and (2) the regeneration potential of the species. PMID:26696137

Techniques for monitoring pileated woodpeckers.

Science.gov (United States)

Evelyn L Bull; Richard S. Holthausen; Marie G. Henjum

1990-01-01

Methods of locating pileated woodpeckers (Dryocopus pileatus) are described, including imitating pileated woodpecker vocalizations, identifying nest and roost trees, and finding foraging signs. Populations of pileated woodpeckers can be monitored by using (1) density of breeding pairs, (2) reproduction, and (3) presence or absence of birds. The...

Social deprivation and population density are not associated with small area risk of amyotrophic lateral sclerosis.

Science.gov (United States)

Rooney, James P K; Tobin, Katy; Crampsie, Arlene; Vajda, Alice; Heverin, Mark; McLaughlin, Russell; Staines, Anthony; Hardiman, Orla

2015-10-01

Evidence of an association between areal ALS risk and population density has been previously reported. We aim to examine ALS spatial incidence in Ireland using small areas, to compare this analysis with our previous analysis of larger areas and to examine the associations between population density, social deprivation and ALS incidence. Residential area social deprivation has not been previously investigated as a risk factor for ALS. Using the Irish ALS register, we included all cases of ALS diagnosed in Ireland from 1995-2013. 2006 census data was used to calculate age and sex standardised expected cases per small area. Social deprivation was assessed using the pobalHP deprivation index. Bayesian smoothing was used to calculate small area relative risk for ALS, whilst cluster analysis was performed using SaTScan. The effects of population density and social deprivation were tested in two ways: (1) as covariates in the Bayesian spatial model; (2) via post-Bayesian regression. 1701 cases were included. Bayesian smoothed maps of relative risk at small area resolution matched closely to our previous analysis at a larger area resolution. Cluster analysis identified two areas of significant low risk. These areas did not correlate with population density or social deprivation indices. Two areas showing low frequency of ALS have been identified in the Republic of Ireland. These areas do not correlate with population density or residential area social deprivation, indicating that other reasons, such as genetic admixture may account for the observed findings. Copyright © 2015 Elsevier Inc. All rights reserved.

Using spatial mark-recapture for conservation monitoring of grizzly bear populations in Alberta.

Science.gov (United States)

Boulanger, John; Nielsen, Scott E; Stenhouse, Gordon B

2018-03-26

One of the challenges in conservation is determining patterns and responses in population density and distribution as it relates to habitat and changes in anthropogenic activities. We applied spatially explicit capture recapture (SECR) methods, combined with density surface modelling from five grizzly bear (Ursus arctos) management areas (BMAs) in Alberta, Canada, to assess SECR methods and to explore factors influencing bear distribution. Here we used models of grizzly bear habitat and mortality risk to test local density associations using density surface modelling. Results demonstrated BMA-specific factors influenced density, as well as the effects of habitat and topography on detections and movements of bears. Estimates from SECR were similar to those from closed population models and telemetry data, but with similar or higher levels of precision. Habitat was most associated with areas of higher bear density in the north, whereas mortality risk was most associated (negatively) with density of bears in the south. Comparisons of the distribution of mortality risk and habitat revealed differences by BMA that in turn influenced local abundance of bears. Combining SECR methods with density surface modelling increases the resolution of mark-recapture methods by directly inferring the effect of spatial factors on regulating local densities of animals.

Imidacloprid-susceptible Nilaparvata lugens individuals exceeded resistant individuals in a mixture population with density pressure.

Science.gov (United States)

Yu, Na; Tian, Jiahua; Zhang, Yixi; Li, Zhong; Liu, Zewen

2018-01-01

Fitness costs associated with insecticide resistance in pest insects have mainly been studied under optimal laboratory conditions. However, resistant insects face more stressors than just insecticides in the field, and how the resistant population reacts to these stressors is of practical importance for the control of pest insects such as the brown planthopper Nilaparvata lugens. The aim of the present study was to explore the impact of population density on the competitiveness of resistant and susceptible individuals. Two isogenic N. lugens populations, a highly imidacloprid-resistant population (HZ-R) with a resistance ratio (RR) of 227.10 and a relatively susceptible population (HZ-S) with an RR of 2.99, were created from a field-resistant population (HZ; RR 62.51). The high resistance levels of HZ-R and HZ were mainly attributable to the overexpression of multiple cytochrome P450 (CYP) genes such as CYP6ER1, CYP6AY1, CYP6CW1 and CYP4CE1 compared with HZ-S, this being supported by piperonyl butoxide synergism. HZ-R was observed to be more resistant to thiacloprid and etofenprox compared with HZ and HZ-S. Most interestingly, in high population density treatments, HZ-S individuals were much more competitive than HZ-R individuals. Imidacloprid-resistant individuals of N. lugens are less competitive than their susceptible counterparts under density pressure. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Predation and physical environment structure the density and population size structure of zebra mussels

OpenAIRE

Naddafi, Rahmat; Pettersson, Kurt; Eklöv, Peter

2010-01-01

The zebra mussel (Dreissena polymorpha) provides one example of successful invaders in novel environments. However, little attention has been devoted to exploring the factors regulating zebra mussel density and population size structure at the local scale. We tested effects of physicochemical factors and fish predation on the density of zebra mussels at several sites and between years in a natural lake. Water depth and roach (Rutilus rutilus) density were the most important variables affectin...

Population density, call-response interval, and survival of out-of-hospital cardiac arrest

Directory of Open Access Journals (Sweden)

Ogawa Toshio

2011-04-01

Full Text Available Abstract Background Little is known about the effects of geographic variation on outcomes of out-of-hospital cardiac arrest (OHCA. The present study investigated the relationship between population density, time between emergency call and ambulance arrival, and survival of OHCA, using the All-Japan Utstein-style registry database, coupled with geographic information system (GIS data. Methods We examined data from 101,287 bystander-witnessed OHCA patients who received emergency medical services (EMS through 4,729 ambulatory centers in Japan between 2005 and 2007. Latitudes and longitudes of each center were determined with address-match geocoding, and linked with the Population Census data using GIS. The endpoints were 1-month survival and neurologically favorable 1-month survival defined as Glasgow-Pittsburgh cerebral performance categories 1 or 2. Results Overall 1-month survival was 7.8%. Neurologically favorable 1-month survival was 3.6%. In very low-density (2 and very high-density (≥10,000/km2 areas, the mean call-response intervals were 9.3 and 6.2 minutes, 1-month survival rates were 5.4% and 9.1%, and neurologically favorable 1-month survival rates were 2.7% and 4.3%, respectively. After adjustment for age, sex, cause of arrest, first aid by bystander and the proportion of neighborhood elderly people ≥65 yrs, patients in very high-density areas had a significantly higher survival rate (odds ratio (OR, 1.64; 95% confidence interval (CI, 1.44 - 1.87; p Conclusion Living in a low-density area was associated with an independent risk of delay in ambulance response, and a low survival rate in cases of OHCA. Distribution of EMS centers according to population size may lead to inequality in health outcomes between urban and rural areas.

Population-based reference values for bone mineral density in young men

DEFF Research Database (Denmark)

Høiberg, M; Nielsen, T L; Wraae, Kristian

2007-01-01

Population-based reference values for peak bone mass density in Danish men. BMD of total hip (1.078 +/- 0,14 g/cm2) differed significantly from values from National Health and Nutrition Examination Survey III and of total lumbar spine ((1.073 +/- 0.125 g/cm2) differed significantly from Hologic...

Near-Saturation Single-Photon Avalanche Diode Afterpulse and Sensitivity Correction Scheme for the LHC Longitudinal density Monitor

CERN Document Server

Bravin, E; Palm, M

2014-01-01

Single-Photon Avalanche Diodes (SPADs) monitor the longitudinal density of the LHC beams by measuring the temporal distribution of synchrotron radiation. The relative population of nominally empty RF-buckets (satellites or ghosts) with respect to filled bunches is a key figure for the luminosity calibration of the LHC experiments. Since afterpulsing from a main bunch avalanche can be as high as, or higher than, the signal from satellites or ghosts, an accurate correction algorithm is needed. Furthermore, to reduce the integration time, the amount of light sent to the SPAD is enough so that pile-up effects and afterpulsing cannot be neglected. The SPAD sensitivity has also been found to vary at the end of the active quenching phase. We present a method to characterize and correct for SPAD deadtime, afterpulsing and sensitivity variation near saturation, together with laboratory benchmarking.

Treaty Monitoring

DEFF Research Database (Denmark)

Canty, M.; Jasani, B.; Lingenfelder, I.

2009-01-01

of remote sensing technologies. The book therefore comprises management aspects (issues and priorities of security research, crisis response), applied methodologies and process chains (treaty monitoring, estimation of population densities and characteristics, border permeability models, damage assessment...... companies, national research institutions and international organizations, all of whom were brought together under the aegis of the European research project GMOSS (Global Monitoring for Security and Stability). This book is tailored for the scientific community that deals with the application of EO data...... of civil security. Written for: Scientists, researchers in spatial sciences as well as practitioners, politicians, decision makers at NGO's in the field of security, crisis management, risk assessment and vulnerability....

Effects of population density on the growth and egg-laying capacity ...

African Journals Online (AJOL)

The effects of the population density of adult African giant land snail, Archachatina marginata on the egg-laying capacity and the growth of the brooders and hatchlings were investigated for 9 months. Ten culture pens were stocked with snails at 20%, 40%, 60%, 80% and 100% capacity with each group in 2 replicates.

Population density equations for stochastic processes with memory kernels

Science.gov (United States)

Lai, Yi Ming; de Kamps, Marc

2017-06-01

We present a method for solving population density equations (PDEs)-a mean-field technique describing homogeneous populations of uncoupled neurons—where the populations can be subject to non-Markov noise for arbitrary distributions of jump sizes. The method combines recent developments in two different disciplines that traditionally have had limited interaction: computational neuroscience and the theory of random networks. The method uses a geometric binning scheme, based on the method of characteristics, to capture the deterministic neurodynamics of the population, separating the deterministic and stochastic process cleanly. We can independently vary the choice of the deterministic model and the model for the stochastic process, leading to a highly modular numerical solution strategy. We demonstrate this by replacing the master equation implicit in many formulations of the PDE formalism by a generalization called the generalized Montroll-Weiss equation—a recent result from random network theory—describing a random walker subject to transitions realized by a non-Markovian process. We demonstrate the method for leaky- and quadratic-integrate and fire neurons subject to spike trains with Poisson and gamma-distributed interspike intervals. We are able to model jump responses for both models accurately to both excitatory and inhibitory input under the assumption that all inputs are generated by one renewal process.

Quorum sensing and density-dependent dispersal in an aquatic model system.

Directory of Open Access Journals (Sweden)

Simon Fellous

Full Text Available Many organisms use cues to decide whether to disperse or not, especially those related to the composition of their environment. Dispersal hence sometimes depends on population density, which can be important for the dynamics and evolution of sub-divided populations. But very little is known about the factors that organisms use to inform their dispersal decision. We investigated the cues underlying density-dependent dispersal in inter-connected microcosms of the freshwater protozoan Paramecium caudatum. In two experiments, we manipulated (i the number of cells per microcosm and (ii the origin of their culture medium (supernatant from high- or low-density populations. We found a negative relationship between population density and rates of dispersal, suggesting the use of physical cues. There was no significant effect of culture medium origin on dispersal and thus no support for chemical cues usage. These results suggest that the perception of density - and as a result, the decision to disperse - in this organism can be based on physical factors. This type of quorum sensing may be an adaptation optimizing small scale monitoring of the environment and swarm formation in open water.

Bayesian inference on the effect of density dependence and weather on a guanaco population from Chile

DEFF Research Database (Denmark)

Zubillaga, Maria; Skewes, Oscar; Soto, Nicolás

2014-01-01

Understanding the mechanisms that drive population dynamics is fundamental for management of wild populations. The guanaco (Lama guanicoe) is one of two wild camelid species in South America. We evaluated the effects of density dependence and weather variables on population regulation based...

Strobe Light Testing and Kokanee Population Monitoring : Dworshak Dam Impacts Assessment and Fisheries Investigation Project, 87-99 : Annual Progress Report.

Energy Technology Data Exchange (ETDEWEB)

Maiolie, Melo A.; Harryman, Bill; Ament, Willaim J.

1999-11-01

We tested the response of kokanee Oncorhynchus nerka to strobe lights. Testing was conducted on wild, free-ranging fish in their natural environment (i.e., the pelagic region of two large Idaho lakes). Split-beam hydroacoustics were used to record the distance kokanee moved away from the lights, as well as the density of kokanee in the area near the lights. In control tests, where strobe lights were lowered into the lake but kept turned off, kokanee remained within a few meters of the lights. Once the lights began flashing, kokanee quickly moved away from the light source. Kokanee moved 20 to 40 m away from the lights in waters with Secchi transparencies from 3 to 5 m. Kokanee densities near the lights were significantly lower (p=0.07 to p=0.00) when the lights were turned on than in control samples with no lights flashing. Flash rates of 300, 360, and 450 flashes/min elicited strong avoidance responses from the fish. Kokanee remained at least 24 m from the lights during our longest test that lasted for 5 h 50 min. We also continued annual monitoring of the kokanee population in Dworshak Reservoir. Spawner counts in four tributary streams that were used as an index of the adult population reached a record low of 144 spawners. No age-1 or age-2 kokanee were caught in 15 trawl hauls used to make population estimates. The population estimate of fry was 65,000 fish, {+-} 76% (90% C.I.). Flooding during the spring of 1996 was responsible for the low kokanee population.

A consumer-resource approach to the density-dependent population dynamics of mutualism.

Science.gov (United States)

Holland, J Nathaniel; DeAngelis, Donald L

2010-05-01

Like predation and competition, mutualism is now recognized as a consumer-resource (C-R) interaction, including, in particular, bi-directional (e.g., coral, plant-mycorrhizae) and uni-directional (e.g., ant-plant defense, plant-pollinator) C-R mutualisms. Here, we develop general theory for the density-dependent population dynamics of mutualism based on the C-R mechanism of interspecific interaction. To test the influence of C-R interactions on the dynamics and stability of bi- and uni-directional C-R mutualisms, we developed simple models that link consumer functional response of one mutualistic species with the resources supplied by another. Phase-plane analyses show that the ecological dynamics of C-R mutualisms are stable in general. Most transient behavior leads to an equilibrium of mutualistic coexistence, at which both species densities are greater than in the absence of interactions. However, due to the basic nature of C-R interactions, certain density-dependent conditions can lead to C-R dynamics characteristic of predator-prey interactions, in which one species overexploits and causes the other to go extinct. Consistent with empirical phenomena, these results suggest that the C-R interaction can provide a broad mechanism for understanding density-dependent population dynamics of mutualism. By unifying predation, competition, and mutualism under the common ecological framework of consumer-resource theory, we may also gain a better understanding of the universal features of interspecific interactions in general.

A consumer-resource approach to the density-dependent population dynamics of mutualism

Science.gov (United States)

Holland, J. Nathaniel; DeAngelis, Donald L.

2010-01-01

Like predation and competition, mutualism is now recognized as a consumer resource (C-R) interaction, including, in particular, bi-directional (e.g., coral, plant- mycorrhizae) and uni-directional (e.g., ant-plant defense, plant-pollinator) C-R mutualisms. Here, we develop general theory for the density-dependent population dynamics of mutualism based on the C-R mechanism of interspecific interaction. To test the influence of C-R interactions on the dynamics and stability of bi- and uni-directional C-R mutualisms, we developed simple models that link consumer functional response of one mutualistic species with the resources supplied by another. Phase-plane analyses show that the ecological dynamics of C-R mutualisms are stable in general. Most transient behavior leads to an equilibrium of mutualistic coexistence, at which both species densities are greater than in the absence of interactions. However, due to the basic nature of C-R interactions, certain density-dependent conditions can lead to C-R dynamics characteristic of predator-prey interactions, in which one species overexploits and causes the other to go extinct. Consistent with empirical phenomena, these results suggest that the C-R interaction can provide a broad mechanism for understanding density-dependent population dynamics of mutualism. By unifying predation, competition, and mutualism under the common ecological framework of consumer-resource theory, we may also gain a better understanding of the universal features of interspecific interactions in general.

Imputation of genotypes from low density (50,000 markers) to high density (700,000 markers) of cows from research herds in Europe, North America, and Australasia using 2 reference populations

DEFF Research Database (Denmark)

Pryce, J E; Johnston, J; Hayes, B J

2014-01-01

detection in genome-wide association studies and the accuracy of genomic selection may increase when the low-density genotypes are imputed to higher density. Genotype data were available from 10 research herds: 5 from Europe [Denmark, Germany, Ireland, the Netherlands, and the United Kingdom (UK)], 2 from...... reference populations. Although it was not possible to use a combined reference population, which would probably result in the highest accuracies of imputation, differences arising from using 2 high-density reference populations on imputing 50,000-marker genotypes of 583 animals (from the UK) were...... information exploited. The UK animals were also included in the North American data set (n = 1,579) that was imputed to high density using a reference population of 2,018 bulls. After editing, 591,213 genotypes on 5,999 animals from 10 research herds remained. The correlation between imputed allele...

Density estimation in tiger populations: combining information for strong inference

Science.gov (United States)

Gopalaswamy, Arjun M.; Royle, J. Andrew; Delampady, Mohan; Nichols, James D.; Karanth, K. Ullas; Macdonald, David W.

2012-01-01

A productive way forward in studies of animal populations is to efficiently make use of all the information available, either as raw data or as published sources, on critical parameters of interest. In this study, we demonstrate two approaches to the use of multiple sources of information on a parameter of fundamental interest to ecologists: animal density. The first approach produces estimates simultaneously from two different sources of data. The second approach was developed for situations in which initial data collection and analysis are followed up by subsequent data collection and prior knowledge is updated with new data using a stepwise process. Both approaches are used to estimate density of a rare and elusive predator, the tiger, by combining photographic and fecal DNA spatial capture–recapture data. The model, which combined information, provided the most precise estimate of density (8.5 ± 1.95 tigers/100 km2 [posterior mean ± SD]) relative to a model that utilized only one data source (photographic, 12.02 ± 3.02 tigers/100 km2 and fecal DNA, 6.65 ± 2.37 tigers/100 km2). Our study demonstrates that, by accounting for multiple sources of available information, estimates of animal density can be significantly improved.

Faunal and vegetation monitoring in response to harbor dredging in the Port of Miami

Science.gov (United States)

Daniels, Andre; Stevenson, Rachael; Smith, Erin; Robblee, Michael

2018-04-11

Seagrasses are highly productive ecosystems. A before-after-control-impact (BACI) design was used to examine effects of dredging on seagrasses and the animals that inhabit them. The control site North Biscayne Bay and the affected site Port of Miami had seagrass densities decrease during both the before, Fish and Invertebrate Assessment Network 2006-2011, and after, Faunal Monitoring in Response to Harbor Dredging 2014-2016, studies. Turbidity levels increased at North Biscayne Bay and Port of Miami basins during the Faunal Monitoring in Response to Harbor Dredging study, especially in 2016. Animal populations decreased significantly in North Biscayne Bay and Port of Miami in the Faunal Monitoring in Response to Harbor Dredging study compared to the Fish and Invertebrate Assessment Network study. Predictive modeling shows that numbers of animal populations will likely continue to decrease if the negative trends in seagrass densities continue unabated. There could be effects on several fisheries vital to the south Florida economy. Additional research could determine if animal populations and seagrass densities have rebounded or continued to decrease.

Long-term monitoring of endangered Laysan ducks: Index validation and population estimates 1998–2012

Science.gov (United States)

Reynolds, Michelle H.; Courtot, Karen; Brinck, Kevin W.; Rehkemper, Cynthia; Hatfield, Jeffrey

2015-01-01

Monitoring endangered wildlife is essential to assessing management or recovery objectives and learning about population status. We tested assumptions of a population index for endangered Laysan duck (or teal; Anas laysanensis) monitored using mark–resight methods on Laysan Island, Hawai’i. We marked 723 Laysan ducks between 1998 and 2009 and identified seasonal surveys through 2012 that met accuracy and precision criteria for estimating population abundance. Our results provide a 15-y time series of seasonal population estimates at Laysan Island. We found differences in detection among seasons and how observed counts related to population estimates. The highest counts and the strongest relationship between count and population estimates occurred in autumn (September–November). The best autumn surveys yielded population abundance estimates that ranged from 674 (95% CI = 619–730) in 2003 to 339 (95% CI = 265–413) in 2012. A population decline of 42% was observed between 2010 and 2012 after consecutive storms and Japan’s To¯hoku earthquake-generated tsunami in 2011. Our results show positive correlations between the seasonal maximum counts and population estimates from the same date, and support the use of standardized bimonthly counts of unmarked birds as a valid index to monitor trends among years within a season at Laysan Island.

Declining Marbled Murrelet density, but not productivity, in the San Juan Islands, Washington, USA

Science.gov (United States)

Teresa J. Lorenz; Martin G. Raphael

2018-01-01

The Marbled Murrelet (Brachyramphus marmoratus) is federally threatened in part of its range in western North America. Information on density and productivity is important for managing populations. Over an 18-yr period, we monitored murrelet density and productivity ratios during the breeding season along 170 km of shoreline of the San Juan Islands...

Occupation and mammographic density: A population-based study (DDM-Occup).

Science.gov (United States)

García-Pérez, Javier; Pollán, Marina; Pérez-Gómez, Beatriz; González-Sánchez, Mario; Cortés Barragán, Rosa Ana; Maqueda Blasco, Jerónimo; González-Galarzo, María Carmen; Alba, Miguel Ángel; van der Haar, Rudolf; Casas, Silvia; Vicente, Cándida; Medina, Pilar; Ederra, María; Santamariña, Carmen; Moreno, María Pilar; Casanova, Francisco; Pedraz-Pingarrón, Carmen; Moreo, Pilar; Ascunce, Nieves; García, Montse; Salas-Trejo, Dolores; Sánchez-Contador, Carmen; Llobet, Rafael; Lope, Virginia

2017-11-01

High mammographic density is one of the main risk factors for breast cancer. Although several occupations have been associated with breast cancer, there are no previous occupational studies exploring the association with mammographic density. Our objective was to identify occupations associated with high mammographic density in Spanish female workers. We conducted a population-based cross-sectional study of occupational determinants of high mammographic density in Spain, based on 1476 women, aged 45-68 years, recruited from seven screening centers within the Spanish Breast Cancer Screening Program network. Reproductive, family, personal, and occupational history data were collected. The latest occupation of each woman was collected and coded according to the 1994 National Classification of Occupations. Mammographic density was assessed from the cranio-caudal mammogram of the left breast using a semi-automated computer-assisted tool. Association between mammographic density and occupation was evaluated by using mixed linear regression models, using log-transformed percentage of mammographic density as dependent variable. Models were adjusted for age, body mass index, menopausal status, parity, smoking, alcohol intake, educational level, type of mammography, first-degree relative with breast cancer, and hormonal replacement therapy use. Screening center and professional reader were included as random effects terms. Mammographic density was higher, although non-statistically significant, among secondary school teachers (e β = 1.41; 95%CI = 0.98-2.03) and nurses (e β = 1.23; 95%CI = 0.96-1.59), whereas workers engaged in the care of people (e β = 0.81; 95%CI = 0.66-1.00) and housewives (e β = 0.87; 95%CI = 0.79-0.95) showed an inverse association with mammographic density. A positive trend for every 5 years working as secondary school teachers was also detected (p-value = 0.035). Nurses and secondary school teachers were the occupations with the highest

Population density of Beauveria bassiana in soil under the action of fungicides and native microbial populations

Directory of Open Access Journals (Sweden)

Flávia Barbosa Soares

2017-08-01

Full Text Available This study investigated whether populations of naturally-occurring soil bacteria, fungi and actinomycetes influence the effect of fungicides on the survival and growth of Beauveria bassiana. The toxicity of methyl thiophanate, pyraclostrobin, mancozeb and copper oxychloride at the recommended doses was analyzed in culture medium and in soil inoculated with fungus at various time points after addition of fungicides. All fungicides completely inhibited the growth and sporulation of B. bassiana in the culture medium. The fungicides were less toxic in soil, emphasizing the action of the microbial populations, which interfered with the toxic effects of these products to the fungus. Actinomycetes had the greatest influence on the entomopathogen, inhibiting it or degrading the fungicides to contribute to the survival and growth of B. bassiana in soil. Native populations of fungi and bacteria had a smaller influence on the population density of B. bassiana and the action of fungicides towards entomopathogen. The toxic effect of the fungicides was greater when added to the soil one hour before or after inoculation than at 48h after inoculation.

Precipitation, density, and population dynamics of desert bighorn sheep on San Andres National Wildlife Refuge, New Mexico

Science.gov (United States)

Bender, L.C.; Weisenberger, M.E.

2005-01-01

Understanding the determinants of population size and performance for desert bighorn sheep (Ovis canadensis mexicana) is critical to develop effective recovery and management strategies. In arid environments, plant communities and consequently herbivore populations are strongly dependent upon precipitation, which is highly variable seasonally and annually. We conducted a retrospective exploratory analysis of desert bighorn sheep population dynamics on San Andres National Wildlife Refuge (SANWR), New Mexico, 1941-1976, by modeling sheep population size as a function of previous population sizes and precipitation. Population size and trend of desert bighorn were best and well described (R 2=0.89) by a model that included only total annual precipitation as a covariate. Models incorporating density-dependence, delayed density-dependence, and combinations of density and precipitation were less informative than the model containing precipitation alone (??AlCc=8.5-22.5). Lamb:female ratios were positively related to precipitation (current year: F1,34=7.09, P=0.012; previous year: F1,33=3.37, P=0.075) but were unrelated to population size (current year. F1,34=0.04, P=0.843; previous year: F1,33 =0.14, P=0.715). Instantaneous population rate of increase (r) was related to population size (F1,33=5.55; P=0.025). Precipitation limited populations of desert bighorn sheep on SANWR primarily in a density-independent manner by affecting production or survival of lambs, likely through influences on forage quantity and quality. Habitat evaluations and recovery plans for desert bighorn sheep need to consider fundamental influences on desert bighorn populations such as precipitation and food, rather than focus solely on proximate issues such as security cover, predation, and disease. Moreover, the concept of carrying capacity for desert bighorn sheep may need re-evaluation in respect to highly variable (CV =35.6%) localized precipitation patterns. On SANWR carrying capacity for desert

Integrating population and genetic monitoring to understand changes in the abundance of a threatened seabird

Science.gov (United States)

Catalina Vásquez-Carrillo; R. William Henry; Laird Henkel; M. Zachariah. Peery

2013-01-01

Population monitoring programs for threatened species are rarely designed to disentangle the effects of movements from changes in birth and death rates on estimated trends in abundance. Here, we illustrate how population and genetic monitoring can be integrated to understand the cause of large changes in the abundance of a threatened species of seabird, the Marbled...

Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

Directory of Open Access Journals (Sweden)

Hartvig Christie

2004-04-01

Full Text Available In eight mesocosms (land based basins macroalgae communities with associated fauna were transplanted from the sea and established during two years. Then, different doses of nutrients (N and P were added to the basins throughout the following three years. During the period of nutrient addition, macroinvertebrate grazers showed seasonal fluctuations with densities usually between 500,000 and 1 million individuals per mesocosm during summer and to a level of about 100,000 during winter. The macroinvertebrate grazers mainly consisted of about 10 species of amphipods and isopods, among which the amphipod Gammarus locusta dominated strongly by biomass. Although the number of predators was very low, the grazer populations never reached a density where considerable grazing impact could be found on the macroalgae. No increase in grazer density was found in the basins with improved nutrient conditions. Thus food quality may be insufficient for further population growth, or density dependant regulation mechanisms may have prevented the grazers from flourishing and overgrazing the system. In aquarium experiments we showed that G. locusta could grow and reproduce on Fucus serratus, Ulva lactuca, periphyton and detritus, and that cannibalism by adult G. locusta on juveniles may have great impact on the population growth. The basins were run with a water flow through system. Nets were placed in front of the inflow and outflow tubes to measure immigration and emigration. Only few individuals (and no Gammarus sp. were recorded in the inflowing water, while high numbers of both amphipods and isopods were found in the outflowing water. Emigration reached peak values during night-time, and it was then two to three times as high as during day-time. Emigration of mobile grazers from the basins amounted to 1-2% of the standing stock daily. These mechanisms that regulate grazers do contribute to maintenance of the seaweed dominance and thus the stability of the seaweed

Density-independent population projection trajectories of chromosome-substituted lines resistant and susceptible to organophosphate insecticides in Drosophila melanogaster

Directory of Open Access Journals (Sweden)

Miyo Takahiro

2004-11-01

Full Text Available Abstract Background Seasonal fluctuations in susceptibility to organophosphate insecticides were observed in the Katsunuma population of Drosophila melanogaster for two consecutive years; susceptibility to three organophosphates tended to increase in the fall. To examine the hypothesis that variation in fitness among resistant and susceptible genotypes could trigger the change of genetic constitution within the fall population, we investigated density-independent population projection trajectories starting from single adult females with characteristics of chromosome-substituted lines resistant and susceptible to the three organophosphates. Results Density-independent population projection trajectories, expressed as the ratios of the number of each chromosome-substituted line to that of line SSS, for which all chromosomes were derived from the susceptible line, showed significant declines in numbers with time for all the resistant chromosome-substituted lines. Conclusion The declining tendency in the density-independent population projection trajectories of the resistant chromosome-substituted lines could explain the simultaneous decline in the levels of resistance to the three organophosphates, observed in the Katsunuma population in the fall.

Disentangling the effects of climate, density dependence, and harvest on an iconic large herbivore's population dynamics

DEFF Research Database (Denmark)

Koons, David; Colchero, Fernando; Hersey, Kent

2015-01-01

Understanding the relative effects of climate, harvest, and density dependence on population dynamics is critical for guiding sound population management, especially for ungulates in arid and semi-arid environments experiencing climate change. To address these issues for bison in southern Utah, we...... than precipitation and other temperature-related variables (model weight > 3 times more than that for other climate variables). Although we hypothesized that harvest is the primary driving force of bison population dynamics in southern Utah, our elasticity analysis indicated that changes in early...... spring temperature could have a greater ‘relative effect’ on equilibrium abundance than either harvest or the strength of density dependence. Our findings highlight the utility of incorporating elasticity analyses into state-space population models, and the need to include climatic processes in wildlife...

A two-population sporadic meteoroid bulk density distribution and its implications for environment models

Science.gov (United States)

Moorhead, Althea V.; Blaauw, Rhiannon C.; Moser, Danielle E.; Campbell-Brown, Margaret D.; Brown, Peter G.; Cooke, William J.

2017-12-01

The bulk density of a meteoroid affects its dynamics in space, its ablation in the atmosphere, and the damage it does to spacecraft and lunar or planetary surfaces. Meteoroid bulk densities are also notoriously difficult to measure, and we are typically forced to assume a density or attempt to measure it via a proxy. In this paper, we construct a density distribution for sporadic meteoroids based on existing density measurements. We considered two possible proxies for density: the KB parameter introduced by Ceplecha and Tisserand parameter, TJ. Although KB is frequently cited as a proxy for meteoroid material properties, we find that it is poorly correlated with ablation-model-derived densities. We therefore follow the example of Kikwaya et al. in associating density with the Tisserand parameter. We fit two density distributions to meteoroids originating from Halley-type comets (TJ 2); the resulting two-population density distribution is the most detailed sporadic meteoroid density distribution justified by the available data. Finally, we discuss the implications for meteoroid environment models and spacecraft risk assessments. We find that correcting for density increases the fraction of meteoroid-induced spacecraft damage produced by the helion/antihelion source.

Sampling Error in Relation to Cyst Nematode Population Density Estimation in Small Field Plots.

Science.gov (United States)

Župunski, Vesna; Jevtić, Radivoje; Jokić, Vesna Spasić; Župunski, Ljubica; Lalošević, Mirjana; Ćirić, Mihajlo; Ćurčić, Živko

2017-06-01

Cyst nematodes are serious plant-parasitic pests which could cause severe yield losses and extensive damage. Since there is still very little information about error of population density estimation in small field plots, this study contributes to the broad issue of population density assessment. It was shown that there was no significant difference between cyst counts of five or seven bulk samples taken per each 1-m 2 plot, if average cyst count per examined plot exceeds 75 cysts per 100 g of soil. Goodness of fit of data to probability distribution tested with χ 2 test confirmed a negative binomial distribution of cyst counts for 21 out of 23 plots. The recommended measure of sampling precision of 17% expressed through coefficient of variation ( cv ) was achieved if the plots of 1 m 2 contaminated with more than 90 cysts per 100 g of soil were sampled with 10-core bulk samples taken in five repetitions. If plots were contaminated with less than 75 cysts per 100 g of soil, 10-core bulk samples taken in seven repetitions gave cv higher than 23%. This study indicates that more attention should be paid on estimation of sampling error in experimental field plots to ensure more reliable estimation of population density of cyst nematodes.

Monitoring the welfare of polar bear populations in a rapidly changing Arctic

Science.gov (United States)

Atwood, Todd C.; Duncan, Colleen G.; Patyk, Kelly A.; Sonsthagen, Sarah A.

2017-01-01

Most programs for monitoring the welfare of wildlife populations support efforts aimed at reaching discrete management objectives, like mitigating conflict with humans. While such programs can be effective, their limited scope may preclude systemic evaluations needed for large-scale conservation initiatives, like the recovery of at-risk species. We discuss select categories of metrics that can be used to monitor how polar bears (Ursus maritimus) are responding to the primary threat to their long-term persistence—loss of sea ice habitat due to the unabated rise in atmospheric greenhouse gas (GHG; e.g., CO2) concentrations—that can also provide information on ecosystem function and health. Monitoring key aspects of polar bear population dynamics, spatial behavior, health and resiliency can provide valuable insight into ecosystem state and function, and could be a powerful tool for achieving Arctic conservation objectives, particularly those that have transnational policy implications.

Microhabitat use, population densities, and size distributions of sulfur cave-dwelling Poecilia mexicana.

Science.gov (United States)

Jourdan, Jonas; Bierbach, David; Riesch, Rüdiger; Schießl, Angela; Wigh, Adriana; Arias-Rodriguez, Lenin; Indy, Jeane Rimber; Klaus, Sebastian; Zimmer, Claudia; Plath, Martin

2014-01-01

The Cueva del Azufre in Tabasco, Mexico, is a nutrient-rich cave and its inhabitants need to cope with high levels of dissolved hydrogen sulfide and extreme hypoxia. One of the successful colonizers of this cave is the poeciliid fish Poecilia mexicana, which has received considerable attention as a model organism to examine evolutionary adaptations to extreme environmental conditions. Nonetheless, basic ecological data on the endemic cave molly population are still missing; here we aim to provide data on population densities, size class compositions and use of different microhabitats. We found high overall densities in the cave and highest densities at the middle part of the cave with more than 200 individuals per square meter. These sites have lower H2S concentrations compared to the inner parts where most large sulfide sources are located, but they are annually exposed to a religious harvesting ceremony of local Zoque people called La Pesca. We found a marked shift in size/age compositions towards an overabundance of smaller, juvenile fish at those sites. We discuss these findings in relation to several environmental gradients within the cave (i.e., differences in toxicity and lighting conditions), but we also tentatively argue that the annual fish harvest during a religious ceremony (La Pesca) locally diminishes competition (and possibly, cannibalism by large adults), which is followed by a phase of overcompensation of fish densities.

The interaction between the spatial distribution of resource patches and population density: consequences for intraspecific growth and morphology.

Science.gov (United States)

Jacobson, Bailey; Grant, James W A; Peres-Neto, Pedro R

2015-07-01

How individuals within a population distribute themselves across resource patches of varying quality has been an important focus of ecological theory. The ideal free distribution predicts equal fitness amongst individuals in a 1 : 1 ratio with resources, whereas resource defence theory predicts different degrees of monopolization (fitness variance) as a function of temporal and spatial resource clumping and population density. One overlooked landscape characteristic is the spatial distribution of resource patches, altering the equitability of resource accessibility and thereby the effective number of competitors. While much work has investigated the influence of morphology on competitive ability for different resource types, less is known regarding the phenotypic characteristics conferring relative ability for a single resource type, particularly when exploitative competition predominates. Here we used young-of-the-year rainbow trout (Oncorhynchus mykiss) to test whether and how the spatial distribution of resource patches and population density interact to influence the level and variance of individual growth, as well as if functional morphology relates to competitive ability. Feeding trials were conducted within stream channels under three spatial distributions of nine resource patches (distributed, semi-clumped and clumped) at two density levels (9 and 27 individuals). Average trial growth was greater in high-density treatments with no effect of resource distribution. Within-trial growth variance had opposite patterns across resource distributions. Here, variance decreased at low-population, but increased at high-population densities as patches became increasingly clumped as the result of changes in the levels of interference vs. exploitative competition. Within-trial growth was related to both pre- and post-trial morphology where competitive individuals were those with traits associated with swimming capacity and efficiency: larger heads/bodies/caudal fins

Effect of Varieties and Plant Population Densities on Dry Matter Production, Radiation Interception and Radiation Energy Conversion in Peanut

Directory of Open Access Journals (Sweden)

agus suprapto

2012-05-01

Full Text Available The solar radiation is one of the major criteria to obtaining advantages on peanuts (Arachishypogaea L.. Although various combinations of crops have been reported, but variety association and plant population densities (PPD during the periodically stage of growth on peanuts have yet to be analyzed. Dry matter production (DM, radiation energy interception, and radiation energy conversions were monitored over the growth period of two varieties of peanut. An experiment was conducted in Jambegede Research Farm, Indonesian Legume and Tuber Crops Research Institute, Malang, East Java, Indonesia, from July until October 2011. The experiment was arranged in a Split Plot Design with three replications. Peanut varieties, as the main plot consisted of two treatments: Kelinci andKancil variety. In addition, five PPD variations as sub plot consisted of 8.1, 11.1, 16.0, 25.0 and 44.4 plant m-2 were arranged in a square spacing. The results showed that DM production from high PPD increased gradually to lower PPD in all varieties. Interception efficiency (IE increased in all varieties from early sowing. A plant population density of 25.0 m-2 and 44.4 plants m-2 intercepted more radiation over 11.1 or 16.0 plants m-2. Conversion efficiency of radiation energy (CE to total dry matter production on Kelinci variety (1.52% indicated a slight higher percentage than on Kancil variety (1.41%. Moreover, the CE and IE values indicated a decrease as the PPD increased on maximum DM.

Accuracy, precision, and economic efficiency for three methods of thrips (Thysanoptera: Thripidae) population density assessment.

Science.gov (United States)

Sutherland, Andrew M; Parrella, Michael P

2011-08-01

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major horticultural pest and an important vector of plant viruses in many parts of the world. Methods for assessing thrips population density for pest management decision support are often inaccurate or imprecise due to thrips' positive thigmotaxis, small size, and naturally aggregated populations. Two established methods, flower tapping and an alcohol wash, were compared with a novel method, plant desiccation coupled with passive trapping, using accuracy, precision and economic efficiency as comparative variables. Observed accuracy was statistically similar and low (37.8-53.6%) for all three methods. Flower tapping was the least expensive method, in terms of person-hours, whereas the alcohol wash method was the most expensive. Precision, expressed by relative variation, depended on location within the greenhouse, location on greenhouse benches, and the sampling week, but it was generally highest for the flower tapping and desiccation methods. Economic efficiency, expressed by relative net precision, was highest for the flower tapping method and lowest for the alcohol wash method. Advantages and disadvantages are discussed for all three methods used. If relative density assessment methods such as these can all be assumed to accurately estimate a constant proportion of absolute density, then high precision becomes the methodological goal in terms of measuring insect population density, decision making for pest management, and pesticide efficacy assessments.

Results of the of wintering bird populations monitoring in the region of Nizhnee Prisurye

Directory of Open Access Journals (Sweden)

Ekaterina S. Preobrazhenskaya

2016-05-01

Full Text Available The monitoring of wintering bird populations in the region of Nizhnee Prisurie on the territory of Chuvash Republic was carried out in 1989–1990. From 2000 censuses were conducted on the territory of the nature reserve "Prisurskiy" and the National Park "Chavash Varmane". These regular censuses were called project "Parus" by the Menzbir Ornithological Society of the Russian Academy of Sciences. The last ten years they were also included in the overall-Russian campaign "Euro-Asian Christmas Bird Counts" project from the Russian Birds Conservation Union. During these 20 years there were 44 bird species registered in the studied area. Eleven of them are marked by single or rare. Four species - Regulus regulus, Aegithalos caudatus, Spinus spinus and Carduelis carduelis – increased their abundance from 1990 till the middle 2000-s and then – decreased. Dendrocopos minor showed the opposite trend. The abundance of 13 species in the 1990-s was higher, sometimes significantly, than in the 2000s and 2010s. The reason may be searched in the differences between the censuses areas in 1990s and 2000s. However, the decreasing of the population densities is typical for other forest species, not only in Nizhnee Prisurie, but also in other model territories. In general, during the last 25 years we can see negative trends in the population dynamics of wintering bird species within the East European plain.

Spatially explicit models for inference about density in unmarked or partially marked populations

Science.gov (United States)

Chandler, Richard B.; Royle, J. Andrew

2013-01-01

Recently developed spatial capture–recapture (SCR) models represent a major advance over traditional capture–recapture (CR) models because they yield explicit estimates of animal density instead of population size within an unknown area. Furthermore, unlike nonspatial CR methods, SCR models account for heterogeneity in capture probability arising from the juxtaposition of animal activity centers and sample locations. Although the utility of SCR methods is gaining recognition, the requirement that all individuals can be uniquely identified excludes their use in many contexts. In this paper, we develop models for situations in which individual recognition is not possible, thereby allowing SCR concepts to be applied in studies of unmarked or partially marked populations. The data required for our model are spatially referenced counts made on one or more sample occasions at a collection of closely spaced sample units such that individuals can be encountered at multiple locations. Our approach includes a spatial point process for the animal activity centers and uses the spatial correlation in counts as information about the number and location of the activity centers. Camera-traps, hair snares, track plates, sound recordings, and even point counts can yield spatially correlated count data, and thus our model is widely applicable. A simulation study demonstrated that while the posterior mean exhibits frequentist bias on the order of 5–10% in small samples, the posterior mode is an accurate point estimator as long as adequate spatial correlation is present. Marking a subset of the population substantially increases posterior precision and is recommended whenever possible. We applied our model to avian point count data collected on an unmarked population of the northern parula (Parula americana) and obtained a density estimate (posterior mode) of 0.38 (95% CI: 0.19–1.64) birds/ha. Our paper challenges sampling and analytical conventions in ecology by demonstrating

Integrated population modeling of black bears in Minnesota: implications for monitoring and management.

Science.gov (United States)

Fieberg, John R; Shertzer, Kyle W; Conn, Paul B; Noyce, Karen V; Garshelis, David L

2010-08-12

Wildlife populations are difficult to monitor directly because of costs and logistical challenges associated with collecting informative abundance data from live animals. By contrast, data on harvested individuals (e.g., age and sex) are often readily available. Increasingly, integrated population models are used for natural resource management because they synthesize various relevant data into a single analysis. We investigated the performance of integrated population models applied to black bears (Ursus americanus) in Minnesota, USA. Models were constructed using sex-specific age-at-harvest matrices (1980-2008), data on hunting effort and natural food supplies (which affects hunting success), and statewide mark-recapture estimates of abundance (1991, 1997, 2002). We compared this approach to Downing reconstruction, a commonly used population monitoring method that utilizes only age-at-harvest data. We first conducted a large-scale simulation study, in which our integrated models provided more accurate estimates of population trends than did Downing reconstruction. Estimates of trends were robust to various forms of model misspecification, including incorrectly specified cub and yearling survival parameters, age-related reporting biases in harvest data, and unmodeled temporal variability in survival and harvest rates. When applied to actual data on Minnesota black bears, the model predicted that harvest rates were negatively correlated with food availability and positively correlated with hunting effort, consistent with independent telemetry data. With no direct data on fertility, the model also correctly predicted 2-point cycles in cub production. Model-derived estimates of abundance for the most recent years provided a reasonable match to an empirical population estimate obtained after modeling efforts were completed. Integrated population modeling provided a reasonable framework for synthesizing age-at-harvest data, periodic large-scale abundance estimates, and

Population growth of Yellowstone grizzly bears: Uncertainty and future monitoring

Science.gov (United States)

Harris, R.B.; White, Gary C.; Schwartz, C.C.; Haroldson, M.A.

2007-01-01

Grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem of the US Rocky Mountains have recently increased in numbers, but remain vulnerable due to isolation from other populations and predicted reductions in favored food resources. Harris et al. (2006) projected how this population might fare in the future under alternative survival rates, and in doing so estimated the rate of population growth, 1983–2002. We address issues that remain from that earlier work: (1) the degree of uncertainty surrounding our estimates of the rate of population change (λ); (2) the effect of correlation among demographic parameters on these estimates; and (3) how a future monitoring system using counts of females accompanied by cubs might usefully differentiate between short-term, expected, and inconsequential fluctuations versus a true change in system state. We used Monte Carlo re-sampling of beta distributions derived from the demographic parameters used by Harris et al. (2006) to derive distributions of λ during 1983–2002 given our sampling uncertainty. Approximate 95% confidence intervals were 0.972–1.096 (assuming females with unresolved fates died) and 1.008–1.115 (with unresolved females censored at last contact). We used well-supported models of Haroldson et al. (2006) and Schwartz et al. (2006a,b,c) to assess the strength of correlations among demographic processes and the effect of omitting them in projection models. Incorporating correlations among demographic parameters yielded point estimates of λ that were nearly identical to those from the earlier model that omitted correlations, but yielded wider confidence intervals surrounding λ. Finally, we suggest that fitting linear and quadratic curves to the trend suggested by the estimated number of females with cubs in the ecosystem, and using AICc model weights to infer population sizes and λ provides an objective means to monitoring approximate population trajectories in addition to demographic

Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density.

Science.gov (United States)

Sugiura, Natsuko; Doi, Kandai; Kato, Takuya; Morita, Tatsushi; Hayama, Shin-Ichi

2018-03-30

To examine outbreaks of mange in raccoon dogs (Nyctereutes procyonoides) with respect to population density, we analyzed camera trap videos, and isolated mites from raccoon dog carcasses. In a camera trapping survey, we categorized the skin condition of raccoon dogs, and used a number of independent videos to calculate the relative abundance index (RAI). The RAI of raccoon dogs with alopecia increased following an increase in the RAI of those without alopecia. Among 27 raccoon dog carcasses, 12 showed mange-compatible skin lesions. Sarcoptes scabiei was isolated from 11 of these raccoon dogs, indicating that sarcoptic mange was endemic in our study area. Therefore, a high relative population density may be a factor underlying epizootics of sarcoptic mange in raccoon dogs.

Development and evaluation of a new method for sampling and monitoring the symphylid population in pineapple

OpenAIRE

Soler, A.; Gaude, J. M.; Marie-Alphonsine, P. A.; Vinatier, F.; Dole, B.; Govindin, J. C.; Fournier, P.; Quénéhervé, Patrick

2011-01-01

BACKGROUND: Symphylids (Hanseniella sp.) are polyphagous soilborne parasites. Today, symphylid populations on pineapple are monitored by observing root symptoms and the presence of symphylids at the bottom of basal leaves. The authors developed a reliable method with a bait and trap device to monitor symphylid populations in pineapple or fallow crops. The spatial distribution of the symphylid populations was evaluated using the variance/mean ratios and spatial analyses based on Moran's and Ge...

Relationship of cancer incidence to terrestrial radiation and population density in Connecticut, 1935-1974

International Nuclear Information System (INIS)

Walter, S.D.; Meigs, J.W.; Heston, J.F.

1986-01-01

The relationship of cancer incidence to terrestrial radiation and population density was investigated. Cancer incidence was obtained using 40 years of age-standardized data from the Connecticut Tumor Registry, and environmental radiation was estimated using data from an airborne gamma radiation survey of the entire state. These variables were examined ecologically, using the 169 towns of the state as the analytic units in a weighted regression analysis. The study design involves a large population base in a state having relatively high terrestrial radiation exposure levels overall and reasonable variation in exposure between towns. For all cancer combined, only one of the eight sex-specific analyses by decade yielded a significant radiation regression coefficient, and this was negative. In the sex- and site-specific analyses, almost all the coefficients for radiation were not significantly different from zero. In contrast, significant positive relationships of cancer incidence with population density were found for all cancer, for cancer of the lung for both sexes, for stomach, colonic, and prostatic cancer for males, and for lymphomas, thyroid, breast, and ovarian cancer for females. Both the radiation and population density relationships were adjusted for socioeconomic status. Socioeconomic status was significantly negatively associated with stomach and lung cancer in males and with cervical cancer in females; it was also positively associated with lymphomas and breast cancer in females. A power calculation revealed that, despite the relatively large size of this study, there was only a small probability of detecting a radiation effect of the strength anticipated from previous estimates

Costs of detection bias in index-based population monitoring

Science.gov (United States)

Moore, C.T.; Kendall, W.L.

2004-01-01

Managers of wildlife populations commonly rely on indirect, count-based measures of the population in making decisions regarding conservation, harvest, or control. The main appeal in the use of such counts is their low material expense compared to methods that directly measure the population. However, their correct use rests on the rarely-tested but often-assumed premise that they proportionately reflect population size, i.e., that they constitute a population index. This study investigates forest management for the endangered Red-cockaded Woodpecker (Picoides borealis) and the Wood Thrush (Hylocichla mustelina) at the Piedmont National Wildlife Refuge in central Georgia, U.S.A. Optimal decision policies for a joint species objective were derived for two alternative models of Wood Thrush population dynamics. Policies were simulated under scenarios of unbiasedness, consistent negative bias, and habitat-dependent negative bias in observed Wood Thrush densities. Differences in simulation outcomes between biased and unbiased detection scenarios indicated the expected loss in resource objectives (here, forest habitat and birds) through decision-making based on biased population counts. Given the models and objective function used in our analysis, expected losses were as great as 11%, a degree of loss perhaps not trivial for applications such as endangered species management. Our analysis demonstrates that costs of uncertainty about the relationship between the population and its observation can be measured in units of the resource, costs which may offset apparent savings achieved by collecting uncorrected population counts.

Colony mapping: A new technique for monitoring crevice-nesting seabirds

Science.gov (United States)

Renner, H.M.; Renner, M.; Reynolds, J.H.; Harping, A.M.A.; Jones, I.L.; Irons, D.B.; Byrd, G.V.

2006-01-01

Monitoring populations of auklets and other crevice-nesting seabirds remains problematic, although numerous methods have been attempted since the mid-1960s. Anecdotal evidence suggests several large auklet colonies have recently decreased in both abundance and extent, concurrently with vegetation encroachment and succession. Quantifying changes in the geographical extent of auklet colonies may be a useful alternative to monitoring population size directly. We propose a standardized method for colony mapping using a randomized systematic grid survey with two components: a simple presence/absence survey and an auklet evidence density survey. A quantitative auklet evidence density index was derived from the frequency of droppings and feathers. This new method was used to map the colony on St. George Island in the southeastern Bering Sea and results were compared to previous colony mapping efforts. Auklet presence was detected in 62 of 201 grid cells (each grid cell = 2500 m2) by sampling a randomly placed 16 m2 plot in each cell; estimated colony area = 155 000 m2. The auklet evidence density index varied by two orders of magnitude across the colony and was strongly correlated with means of replicated counts of birds socializing on the colony surface. Quantitatively mapping all large auklet colonies is logistically feasible using this method and would provide an important baseline for monitoring colony status. Regularly monitoring select colonies using this method may be the best means of detecting changes in distribution and population size of crevice-nesting seabirds. ?? The Cooper Ornithological Society 2006.

The relationship between male moth density and female mating success in invading populations of Lymantria dispar

Science.gov (United States)

Patrick C. Tobin; Ksenia S. Onufrieva; Kevin W. Thorpe

2012-01-01

The successful establishment of non-native species in new areas can be affected by many factors including the initial size of the founder population. Populations comprised of fewer individuals tend to be subject to stochastic forces and Allee effects (positive-density dependence), which can challenge the ability of small founder populations to establish in a new area....

Deer presence rather than abundance determines the population density of the sheep tick, Ixodes ricinus, in Dutch forests

NARCIS (Netherlands)

Hofmeester, Tim R.; Sprong, Hein; Jansen, Patrick A.; Prins, Herbert H.T.; Wieren, Van Sipke E.

2017-01-01

Background: Understanding which factors drive population densities of disease vectors is an important step in assessing disease risk. We tested the hypothesis that the density of ticks from the Ixodes ricinus complex, which are important vectors for tick-borne diseases, is determined by the density

Monitoring diesel particulate matter and calculating diesel particulate densities using Grimm model 1.109 real-time aerosol monitors in underground mines.

Science.gov (United States)

Kimbal, Kyle C; Pahler, Leon; Larson, Rodney; VanDerslice, Jim

2012-01-01

Currently, there is no Mine Safety and Health Administration (MSHA)-approved sampling method that provides real-time results for ambient concentrations of diesel particulates. This study investigated whether a commercially available aerosol spectrometer, the Grimm Portable Aerosol Spectrometer Model 1.109, could be used during underground mine operations to provide accurate real-time diesel particulate data relative to MSHA-approved cassette-based sampling methods. A subset was to estimate size-specific diesel particle densities to potentially improve the diesel particulate concentration estimates using the aerosol monitor. Concurrent sampling was conducted during underground metal mine operations using six duplicate diesel particulate cassettes, according to the MSHA-approved method, and two identical Grimm Model 1.109 instruments. Linear regression was used to develop adjustment factors relating the Grimm results to the average of the cassette results. Statistical models using the Grimm data produced predicted diesel particulate concentrations that highly correlated with the time-weighted average cassette results (R(2) = 0.86, 0.88). Size-specific diesel particulate densities were not constant over the range of particle diameters observed. The variance of the calculated diesel particulate densities by particle diameter size supports the current understanding that diesel emissions are a mixture of particulate aerosols and a complex host of gases and vapors not limited to elemental and organic carbon. Finally, diesel particulate concentrations measured by the Grimm Model 1.109 can be adjusted to provide sufficiently accurate real-time air monitoring data for an underground mining environment.

International Consortium on Mammographic Density : Methodology and population diversity captured across 22 countries

NARCIS (Netherlands)

McCormack, Valerie A; Burton, Anya; Dos-Santos-Silva, Isabel; Hipwell, John H; Dickens, Caroline; Salem, Dorria; Kamal, Rasha; Hartman, Mikael; Lee, Charmaine Pei Ling; Chia, Kee-Seng; Ozmen, Vahit; Aribal, Mustafa Erkin; Flugelman, Anath Arzee; Lajous, Martín; Lopez-Riduara, Ruy; Rice, Megan; Romieu, Isabelle; Ursin, Giske; Qureshi, Samera; Ma, Huiyan; Lee, Eunjung; van Gils, Carla H; Wanders, Johanna O P; Vinayak, Sudhir; Ndumia, Rose; Allen, Steve; Vinnicombe, Sarah; Moss, Sue; Won Lee, Jong; Kim, Jisun; Pereira, Ana; Garmendia, Maria Luisa; Sirous, Reza; Sirous, Mehri; Peplonska, Beata; Bukowska, Agnieszka; Tamimi, Rulla M; Bertrand, Kimberly; Nagata, Chisato; Kwong, Ava; Vachon, Celine; Scott, Christopher; Perez-Gomez, Beatriz; Pollan, Marina; Maskarinec, Gertraud; Giles, Graham; Hopper, John; Stone, Jennifer; Rajaram, Nadia; Teo, Soo-Hwang; Mariapun, Shivaani; Yaffe, Martin J; Schüz, Joachim; Chiarelli, Anna M; Linton, Linda; Boyd, Norman F

2015-01-01

Mammographic density (MD) is a quantitative trait, measurable in all women, and is among the strongest markers of breast cancer risk. The population-based epidemiology of MD has revealed genetic, lifestyle and societal/environmental determinants, but studies have largely been conducted in women with

Measurements of beam halo diffusion and population density in the Tevatron and in the Large Hadron Collider

CERN Document Server

Stancari, Giulio

Halo dynamics influences global accelerator performance: beam lifetimes, emittance growth, dynamic aperture, and collimation efficiency. Halo monitoring and control are also critical for the operation of high-power machines. For instance, in the high-luminosity upgrade of the LHC, the energy stored in the beam tails may reach several megajoules. Fast losses can result in superconducting magnet quenches, magnet damage, or even collimator deformation. The need arises to measure the beam halo and to remove it at controllable rates. In the Tevatron and in the LHC, halo population densities and diffusivities were measured with collimator scans by observing the time evolution of losses following small inward or outward collimator steps, under different experimental conditions: with single beams and in collision, and, in the case of the Tevatron, with a hollow electron lens acting on a subset of bunches. After the LHC resumes operations, it is planned to compare measured diffusivities with the known strength of tran...

Deer presence rather than abundance determines the population density of the sheep tick, Ixodes ricinus, in Dutch forests.

NARCIS (Netherlands)

Hofmeester, Tim R; Sprong, Hein; Jansen, Patrick A; Prins, Herbert H T; van Wieren, Sipke E

2017-01-01

Understanding which factors drive population densities of disease vectors is an important step in assessing disease risk. We tested the hypothesis that the density of ticks from the Ixodes ricinus complex, which are important vectors for tick-borne diseases, is determined by the density of deer, as

Periodic fluctuations in correlation-based connectivity density time series: Application to wind speed-monitoring network in Switzerland

Science.gov (United States)

Laib, Mohamed; Telesca, Luciano; Kanevski, Mikhail

2018-02-01

In this paper, we study the periodic fluctuations of connectivity density time series of a wind speed-monitoring network in Switzerland. By using the correlogram-based robust periodogram annual periodic oscillations were found in the correlation-based network. The intensity of such annual periodic oscillations is larger for lower correlation thresholds and smaller for higher. The annual periodicity in the connectivity density seems reasonably consistent with the seasonal meteo-climatic cycle.

Plant quality and conspecific density effects on Anaphothrips obscurus (Thysanoptera: Thripidae) wing diphenism and population ecology.

Science.gov (United States)

Reisig, Dominic D; Godfrey, Larry D; Marcum, Daniel B

2010-04-01

Factors that influence thysanopteran wing diphenism are not well known. In these studies, the impact of food quality, mediated through nitrogen addition, and conspecific density was explored on the wing diphenism of an herbivorous thrips species (Anaphothrips obscurus Müller) (Thysanoptera: Thripidae). In the first study, nitrogen was added to timothy grass (Phleum pretense L.) (Poales: Poaceae) transplants, and naturally occurring thrips populations were caged on the plants. Thrips abundance and foliar nutrients were assessed every 2 wk. A separate factorial experiment in growth chambers explored the impact of both plant nitrogen addition and thrips abundance on wing diphenism. Thrips density was manipulated by adding either 3 or 40 thrips to potted and caged timothy. Thrips abundance and foliar nutrients were measured 58 d after treatment placement. Plant quality directly affected thrips wing diphenism independent of thrips density in both experiments. Near the end of the field cage experiment, density may have indirectly impacted wing diphenism. In both experiments, plant quality and thrips density interacted to affect thrips population abundance. Plant quality alone can affect thrips wing diphenism, but it remains unclear whether density alone can affect thrips wing diphenism. This is a unique and understudied system that will be useful to examine generalized theories on the negative interaction between reproduction and dispersal.

Effects of Student Population Density on Academic Achievement in Georgia Elementary Schools.

Science.gov (United States)

Swift, Diane O'Rourke

The purpose of this study was to determine the relationship between school density and achievement test scores. The study utilized a bipolar sample in order to include schools whose achievement scores were at the top and bottom of the population spectrum when considering Iowa Tests of Basic Skills (ITBS) scores. Based on comparing test scores and…

Relationship between tea drinking and bone mineral density in Bushehr population

Directory of Open Access Journals (Sweden)

Somayeh Amiri

2011-09-01

Full Text Available Background: Tea consumption is common throughout the world, especially in Iran and it was known as the most common beverages. Several studies evaluated negative effect of coffee and relationship between its caffeine content with bone density. But relationship between tea drinking and bone mineral density is less observed. Considering high amount of tea consumption and prevalence of osteoporosis in Iran, it is important to investigate this relationship.Materials and Method: Population study includes 1125 subjects (aged 20- 72 years randomly selected by cluster sampling in Bushehr, who participated in general project of prevention and treatment of osteoporosis. The participants were categorized based on degree of tea consumption: high tea drinkers (more than 4 cups of tea per day and low tea drinkers (equal or less than 4 cups of tea per day.Results: In high tea drinkers, mean score for bone density was significantly higher in neck and total femur. But this difference in isolated groups (according to sex, age and both of them was not seen.Conclusion: The result of this study indicates on a direct relationship between tea drinking and increasing of bone mineral density. Moreover, it shows the prevalence of osteoporosis is lower in people who have a regular daily habit of tea consumption

Population density, sexual reproduction and diapause in monogonont rotifers: new data for Brachionus and a review

Directory of Open Access Journals (Sweden)

John J. GILBERT

2004-09-01

Full Text Available Diapausing, fertilized eggs in monogonont rotifers typically are formed after an environmental signal induces amictic females to produce mictic daughters. Mictic females lay haploid eggs that may develop parthenogenetically into males, or that may be fertilized and develop into diapausing, female embryos called resting eggs. Laboratory experiments demonstrate that crowding is the signal for production of mictic females in strains of Brachionus calyciflorus from Texas, Spain and Germany, and in a strain of Brachionus variabilis from Spain. In these experiments, newborn amictic females were cultured singly in large and small volumes to give lowand high-density treatments. Therefore, the induction of mictic females is due exclusively to population density and cannot be attributed to a grouping effect involving some interaction among individuals. B. variabilis is very sensitive to population density; females had to be cultured in 30 ml to prevent appreciable production of mictic daughters. Crowding is now known to be the signal for initiation of sexuality and diapause in four species of Brachionus, two species of Epiphanes, and Rhinoglena frontalis. The chemical that mediates this response somehow influences oocytes in the maternal body cavity to differentiate into mictic females. Aggregation of individuals in natural systems may facilitate the production of mictic females. In some of these rotifers, the response to crowding is suppressed in early generations from the resting egg, assuring that clonal populations will attain higher population densities before committing to sexual reproduction. Fitness benefits of the mictic-female response to crowding, and to other environmental signals in other rotifers (dietary tocopherol, long photoperiod, are discussed.

Evaluation of sweet sorghum (Sorghum bicolor L. [Moench]) on several population density for bioethanol production

Science.gov (United States)

Suwarti; Efendi, R.; Massinai, R.; Pabendon, M. B.

2018-03-01

Sweet sorghum (Sorghum bicolor L. [Moench]) crop management that is use for raw source of bioethanol for industrial purpose in Indonesia is less developed. The aim of this research was to evaluated sweet sorghum variety at several population to determine optimum density for juice production. Experiment design was set on split-plot design with three replications, conducted on August to December 2016 at the Indonesian Cereals Research Institute Research Station, Maros South Sulawesi. Main plot were six variation of plant row, and sub plot were three sweet sorghum varieties. Result of the study showed that plant population was high significanty affect to stalk weight, total biomass yield, leaf weight, and also significantly affect bagass weight and juice volume. Varieties were high significantly different in plant height, juice volume, and number of nodes. Super 1 variety on population at 166,667 plants/ha (P1) was obtained the highest juice volume (19,445 lHa-1), meanwhile the highest brix value obtained from Numbu at the same plants population. Furthermore juice volume had significant correlation with biomass weight at the r=0.73. Based on ethanol production, Super 2 and Numbu had the highest volume at 83.333 plants/ha density (P3) and Super 1 at 166.667 plants/ha density with the ethanol volume were 827.68 l Ha-1, 1116.50 l/ha and 993.62 l Ha-1 respectively.

Optimizing Use of Girdled Ash Trees for Management of Low-Density Emerald Ash Borer (Coleoptera: Buprestidae) Populations.

Science.gov (United States)

Siegert, Nathan W; McCullough, Deborah G; Poland, Therese M; Heyd, Robert L

2017-06-01

Effective survey methods to detect and monitor recently established, low-density infestations of emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), remain a high priority because they provide land managers and property owners with time to implement tactics to slow emerald ash borer population growth and the progression of ash mortality. We evaluated options for using girdled ash (Fraxinus spp.) trees for emerald ash borer detection and management in a low-density infestation in a forested area with abundant green ash (F. pennsylvanica). Across replicated 4-ha plots, we compared detection efficiency of 4 versus 16 evenly distributed girdled ash trees and between clusters of 3 versus 12 girdled trees. We also examined within-tree larval distribution in 208 girdled and nongirdled trees and assessed adult emerald ash borer emergence from detection trees felled 11 mo after girdling and left on site. Overall, current-year larvae were present in 85-97% of girdled trees and 57-72% of nongirdled trees, and larval density was 2-5 times greater on girdled than nongirdled trees. Low-density emerald ash borer infestations were readily detected with four girdled trees per 4-ha, and 3-tree clusters were as effective as 12-tree clusters. Larval densities were greatest 0.5 ± 0.4 m below the base of the canopy in girdled trees and 1.3 ± 0.7 m above the canopy base in nongirdled trees. Relatively few adult emerald ash borer emerged from trees felled 11 mo after girdling and left on site through the following summer, suggesting removal or destruction of girdled ash trees may be unnecessary. This could potentially reduce survey costs, particularly in forested areas with poor accessibility. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

Country roads, take me home… to my friends: How intelligence, population density, and friendship affect modern happiness.

Science.gov (United States)

Li, Norman P; Kanazawa, Satoshi

2016-11-01

We propose the savanna theory of happiness, which suggests that it is not only the current consequences of a given situation but also its ancestral consequences that affect individuals' life satisfaction and explains why such influences of ancestral consequences might interact with intelligence. We choose two varied factors that characterize basic differences between ancestral and modern life - population density and frequency of socialization with friends - as empirical test cases. As predicted by the theory, population density is negatively, and frequency of socialization with friends is positively, associated with life satisfaction. More importantly, the main associations of life satisfaction with population density and socialization with friends significantly interact with intelligence, and, in the latter case, the main association is reversed among the extremely intelligent. More intelligent individuals experience lower life satisfaction with more frequent socialization with friends. This study highlights the utility of incorporating evolutionary perspectives in the study of subjective well-being. © 2016 The British Psychological Society.

Development and validation of spectroscopic methods for monitoring density changes in pressurized gaseous and supercritical fluid systems.

Science.gov (United States)

Blatchford, Marc A; Wallen, Scott L

2002-04-15

The further development of new processes utilizing liquid or supercritical CO2 as a solvent will benefit from the rational design of new CO2-philes. Understanding solvation structures and mechanisms of these molecules is an important part of this process. In such studies, determining the change in density as a function of the measured thermodynamic conditions (pressure and temperature) provides an excellent means of directly monitoring the solution conditions in the detection volume for a given technique. By integrating spectroscopic peaks, changes in area can be used to determine changes in analyte concentration in the detection volume, and thus, it should be possible to monitor the system density in situ. In the present study, we examine the utility of Raman and NMR spectroscopy as a means of following changes in solution density conditions and validate this approach in pure fluids and gases (N2 and CO2) and supercritical fluid mixtures (acetaldehyde vapor in N2). In addition, we present the design of a simple, inexpensive cell for conducting Raman and NMR measurements under moderate pressure conditions.

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Directory of Open Access Journals (Sweden)

Munyuli Théodore

2017-10-01

Full Text Available Sweetpotato is a major food security crop grown in eastern Democratic Republic of Congo. Its production is however limited due to high prevalence of pests and diseases among other abiotic and biotic factors. A study was designed to aid understanding the knowledge of farmers about pests and their perception about climate variability impacts, as well as documenting the phenology of sweetpotato pests (pest population dynamics in relationship with weather factors. The paper aimed at determined which climatic factors may be used as best predictors of the different status of pest populations (declines, outbreaks. Farmer based data was obtained using a semi structured questionnaire administered to several of farmers. Population dynamics of sweetpotato pests were monitored year-round from 2005 to 2015 in South Kivu province, eastern DRCongo. Field monitoring (visual counts observations (population dynamic of different soil-dwelling and surface dwelling arthropods visiting sweetpotato fields combined with a survey of farmers’ knowledge on sweetpotato pests and their practices in the management of these pests in South- Kivu Province were conducted for 11 years. Monitoring (with field observations and counts was carried out in fields under different farming practices (monocropping and inter-cropping in sites located at different altitudes. Similarly, data for climatic factors, for the same period, were collected from Lwiro Research center. Regression models were applied to understand the linkages between environmental factors (rainfall and temperature and pest population dynamics. The results indicated that different varieties (local and improved ones of sweetpotato are grown three times (3 seasons per annum under various cropping systems (sole crop, mixed crops in various agroecological zones at different altitudes. Various arthropod species visit the crop at its different stages of development including classically known pests (Acraea acerata, Cylas

Population density of oil palm pollinator weevil Elaeidobius kamerunicus based on seasonal effect and age of oil palm

Science.gov (United States)

Daud, Syarifah Nadiah Syed Mat; Ghani, Idris Abd.

2016-11-01

The pollinating weevil, Elaedobius kamerunicus (EK) has been known to be the most efficient insect pollinator of oil palm, and has successfully improved the oil palm pollination and increased the yield. Its introduction has greatly reduced the need for assisted pollination. The purpose of this study was to identify the population density of oil palm pollinator weevil EK using the concept of pollinator force and to relate the population density with the seasonal effect and the age of oil palm at Lekir Oil Palm Plantation Batu 14, Perak, Peninsular Malaysia. The pollinator force of the weevil was sustained at a range between 3095.2 to 19126.1 weevils per ha. The overall mean of weevil per spikelet shows that the range of weevil was between 13.51 and 54.06 per spikelet. There was no correlation between rainfall and population density of EK. However, positive correlation was obtained between weevil density and the number of anthesising female inflorescence of oil palm (r= 0.938, poil palm stands had significantly different population density than that of a 8-year old oil palm stand. The information of this study should be useful as a baseline data to investigate why there is such a wide range of weevils per ha or spikelet. Further study should also be done to relate the number pollinator force per spikelete and the Fresh fruit Bunch (FFB), fruit set or fruit to bunch ratio.

Integrated population modeling of black bears in Minnesota: implications for monitoring and management.

Directory of Open Access Journals (Sweden)

John R Fieberg

Full Text Available BACKGROUND: Wildlife populations are difficult to monitor directly because of costs and logistical challenges associated with collecting informative abundance data from live animals. By contrast, data on harvested individuals (e.g., age and sex are often readily available. Increasingly, integrated population models are used for natural resource management because they synthesize various relevant data into a single analysis. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the performance of integrated population models applied to black bears (Ursus americanus in Minnesota, USA. Models were constructed using sex-specific age-at-harvest matrices (1980-2008, data on hunting effort and natural food supplies (which affects hunting success, and statewide mark-recapture estimates of abundance (1991, 1997, 2002. We compared this approach to Downing reconstruction, a commonly used population monitoring method that utilizes only age-at-harvest data. We first conducted a large-scale simulation study, in which our integrated models provided more accurate estimates of population trends than did Downing reconstruction. Estimates of trends were robust to various forms of model misspecification, including incorrectly specified cub and yearling survival parameters, age-related reporting biases in harvest data, and unmodeled temporal variability in survival and harvest rates. When applied to actual data on Minnesota black bears, the model predicted that harvest rates were negatively correlated with food availability and positively correlated with hunting effort, consistent with independent telemetry data. With no direct data on fertility, the model also correctly predicted 2-point cycles in cub production. Model-derived estimates of abundance for the most recent years provided a reasonable match to an empirical population estimate obtained after modeling efforts were completed. CONCLUSIONS/SIGNIFICANCE: Integrated population modeling provided a reasonable

An Evaluation of Population Density Mapping and Built up Area Estimates in Sri Lanka Using Multiple Methodologies

Science.gov (United States)

Engstrom, R.; Soundararajan, V.; Newhouse, D.

2017-12-01

In this study we examine how well multiple population density and built up estimates that utilize satellite data compare in Sri Lanka. The population relationship is examined at the Gram Niladhari (GN) level, the lowest administrative unit in Sri Lanka from the 2011 census. For this study we have two spatial domains, the whole country and a 3,500km2 sub-sample, for which we have complete high spatial resolution imagery coverage. For both the entire country and the sub-sample we examine how consistent are the existing publicly available measures of population constructed from satellite imagery at predicting population density? For just the sub-sample we examine how well do a suite of values derived from high spatial resolution satellite imagery predict population density and how does our built up area estimate compare to other publicly available estimates. Population measures were obtained from the Sri Lankan census, and were downloaded from Facebook, WorldPoP, GPW, and Landscan. Percentage built-up area at the GN level was calculated from three sources: Facebook, Global Urban Footprint (GUF), and the Global Human Settlement Layer (GHSL). For the sub-sample we have derived a variety of indicators from the high spatial resolution imagery. Using deep learning convolutional neural networks, an object oriented, and a non-overlapping block, spatial feature approach. Variables calculated include: cars, shadows (a proxy for building height), built up area, and buildings, roof types, roads, type of agriculture, NDVI, Pantex, and Histogram of Oriented Gradients (HOG) and others. Results indicate that population estimates are accurate at the higher, DS Division level but not necessarily at the GN level. Estimates from Facebook correlated well with census population (GN correlation of 0.91) but measures from GPW and WorldPop are more weakly correlated (0.64 and 0.34). Estimates of built-up area appear to be reliable. In the 32 DSD-subsample, Facebook's built- up area measure

Increase in density of genetically diverse invasive Asian shore crab (Hemigrapsus sanguineus) populations in the Gulf of Maine.

Science.gov (United States)

Lord, Joshua P; Williams, Larissa M

2017-04-01

Hemigrapsus sanguineus , the Asian shore crab, has rapidly replaced Carcinus maenas , the green crab, as the most abundant crab on rocky shores in the northwest Atlantic since its introduction to the United States (USA) in 1988. The northern edge of this progressing invasion is the Gulf of Maine, where Asian shore crabs are only abundant in the south. We compared H. sanguineus population densities to those from published 2005 surveys and quantified genetic variation using the cytochrome c oxidase subunit I gene. We found that the range of H. sanguineus had extended northward since 2005, that population density had increased substantially (at least 10-fold at all sites), and that Asian shore crabs had become the dominant intertidal crab species in New Hampshire and southern Maine. Despite the significant increase in population density of H. sanguineus , populations only increased by a factor of 14 in Maine compared to 70 in southern New England, possibly due to cooler temperatures in the Gulf of Maine. Genetically, populations were predominantly composed of a single haplotype of Japanese, Korean, or Taiwanese origin, although an additional seven haplotypes were found. Six of these haplotypes were of Asian origin, while two are newly described. Large increases in population sizes of genetically diverse individuals in Maine will likely have a large ecological impact, causing a reduction in populations of mussels, barnacles, snails, and other crabs, similar to what has occurred at southern sites with large populations of this invasive crab species.

Medical And Genetic Monitoring of Population Around Semipalatinsk Test-site

International Nuclear Information System (INIS)

Kayupova, N.A.; Svyatova, G.S.; Abildinova, G.Zh.

1998-01-01

Up to present, there is no one positive opinion about the effect of a small amount of ionizing radiation doses on the genetic system of a human being. In connection with it, the all-round medical and genetic researches conducted by a united methodical basis and intended to study general mutagen and teratogen radiation effects are of a certain significance. With that end in view, the medical and genetic testing of a number of rural population around Semipalatinsk test-site (STS) was conducted. The all-round methods of medical and genetic consequences evaluation were developed, and 'active revealing of the congenital fetation disease (CFD)' method was submitted for consideration. Aside from analysis of the general genetic and demographic data, outcomes of more than 160.000 confinements were studied, and a high frequency rate of the CFD of 'the strict recording' (6.11 per 1000 new-born children in areas of extreme radiation hazard) was discovered, that surely exceeded the similar index for the monitored areas (2.92 per 1000 new-born children). A higher frequency rate of the Down's syndrome and numerous CFD (1.66 and 1.07 per 1000 new-born children accordingly) were revealed as well. As a result of the cytogenetic monitoring of the tested population, it was ascertained that a total frequency rate of the aberrant cell emergence was equal to 4.9 per 100 cells, that is 3.9 times as much than the similar index for the monitored area. A high frequency rate of the markers induced by radiation was discovered, which proved the increased mutagen effect of the environment. Biological presentation of the radiation effect on population was conducted in two methods of the biological monitoring, and according to the frequency rate of the chromosomal aberrations in lymphocytes of peripheral blood, that are induced by radiation, and electro paramagnetic resonance of teeth enamel (Kazakhstan national Nuclear Center). The results of the medical and genetic research conducted were an

Development and evaluation of a new method for sampling and monitoring the symphylid population in pineapple.

Science.gov (United States)

Soler, Alain; Gaude, Jean-Marie; Marie-Alphonsine, Paul-Alex; Vinatier, Fabrice; Dole, Bernard; Govindin, Jean-Claude; Fournier, Patrick; Queneherve, Patrick

2011-09-01

Symphylids (Hanseniella sp.) are polyphagous soilborne parasites. Today, symphylid populations on pineapple are monitored by observing root symptoms and the presence of symphylids at the bottom of basal leaves. The authors developed a reliable method with a bait and trap device to monitor symphylid populations in pineapple or fallow crops. The spatial distribution of the symphylid populations was evaluated using the variance/mean ratios and spatial analyses based on Moran's and Geary's indices. The method has been tested to monitor symphylid populations at different developmental stages of pineapple. Adding potato baits to the soil samples increased the trapping efficiency of symphylids when compared with 'soil only' and 'bait only' methods. The handling of the samples is also facilitated by the new device. Results showed that the vertical distribution of symphylids may be uniform deeply inside the soil profile under pineapple, up to 50 cm. Results showed that symphylid populations are highly aggregated, showing a spot area about 4-6 m wide for their development. The new method allows better and easier evaluation of symphylid populations. It may be very useful in the evaluation of new IPM methods to control symphylids under pineapple. Copyright © 2011 Society of Chemical Industry.

A regional-scale, high resolution dynamical malaria model that accounts for population density, climate and surface hydrology.

Science.gov (United States)

Tompkins, Adrian M; Ermert, Volker

2013-02-18

The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions.

Evaluating and improving count-based population inference: A case study from 31 years of monitoring Sandhill Cranes

Science.gov (United States)

Gerber, Brian D.; Kendall, William L.

2017-01-01

Monitoring animal populations can be difficult. Limited resources often force monitoring programs to rely on unadjusted or smoothed counts as an index of abundance. Smoothing counts is commonly done using a moving-average estimator to dampen sampling variation. These indices are commonly used to inform management decisions, although their reliability is often unknown. We outline a process to evaluate the biological plausibility of annual changes in population counts and indices from a typical monitoring scenario and compare results with a hierarchical Bayesian time series (HBTS) model. We evaluated spring and fall counts, fall indices, and model-based predictions for the Rocky Mountain population (RMP) of Sandhill Cranes (Antigone canadensis) by integrating juvenile recruitment, harvest, and survival into a stochastic stage-based population model. We used simulation to evaluate population indices from the HBTS model and the commonly used 3-yr moving average estimator. We found counts of the RMP to exhibit biologically unrealistic annual change, while the fall population index was largely biologically realistic. HBTS model predictions suggested that the RMP changed little over 31 yr of monitoring, but the pattern depended on assumptions about the observational process. The HBTS model fall population predictions were biologically plausible if observed crane harvest mortality was compensatory up to natural mortality, as empirical evidence suggests. Simulations indicated that the predicted mean of the HBTS model was generally a more reliable estimate of the true population than population indices derived using a moving 3-yr average estimator. Practitioners could gain considerable advantages from modeling population counts using a hierarchical Bayesian autoregressive approach. Advantages would include: (1) obtaining measures of uncertainty; (2) incorporating direct knowledge of the observational and population processes; (3) accommodating missing years of data; and (4

Shifts of community composition and population density substantially affect ecosystem function despite invariant richness

NARCIS (Netherlands)

Spaak, Jurg W.; Baert, Jan M.; Baird, Donald J.; Eisenhauer, Nico; Maltby, Lorraine; Pomati, Francesco; Radchuk, Viktoriia; Rohr, Jason R.; Brink, van den Paul J.; Laender, De Frederik

2017-01-01

There has been considerable focus on the impacts of environmental change on ecosystem function arising from changes in species richness. However, environmental change may affect ecosystem function without affecting richness, most notably by affecting population densities and community

Effects of temperature and population density on von Bertalanffy growth parameters in Atlantic herring: a macro-ecological analysis

NARCIS (Netherlands)

Brunel, T.P.A.; Dickey-Collas, M.

2010-01-01

The effect of temperature and population density on the growth of Atlantic herring Clupea harengus was studied using a comparative approach applied to 15 North Atlantic populations. The von Bertalanffy (VB) equation was applied to describe mean growth of individuals in each population, both averaged

Diet quality limits summer growth of field vole populations.

Directory of Open Access Journals (Sweden)

Kristian M Forbes

Full Text Available Marked variation occurs in both seasonal and multiannual population density peaks of northern European small mammal species, including voles. The availability of dietary proteins is a key factor limiting the population growth of herbivore species. The objective of this study is to investigate the degree to which protein availability influences the growth of increasing vole populations. We hypothesise that the summer growth of folivorous vole populations is positively associated with dietary protein availability. A field experiment was conducted over a summer reproductive period in 18 vegetated enclosures. Populations of field voles (Microtus agrestis were randomised amongst three treatment groups: 1 food supplementation with ad libitum high protein (30% dry weight pellets, 2 food supplementation with ad libitum low protein (1% dry weight; both supplemented foods had equivalent energy content pellets, and 3 control (no food supplementation, n = 6 per treatment. Vole density, survival, demographic attributes and condition indicators were monitored with live-trapping and blood sampling. Highest final vole densities were attained in populations that received high protein supplementation and lowest in low protein populations. Control populations displayed intermediate densities. The survival rate of voles was similar in all treatment groups. The proportion of females, and of those that were pregnant or lactating, was highest in the high protein supplemented populations. This suggests that variation in reproductive, rather than survival rates of voles, accounted for density differences between the treatment groups. We found no clear association between population demography and individual physiological condition. Our results demonstrate that dietary protein availability limits vole population growth during the summer growing season. This suggests that the nutritional quality of forage may be an underestimated source of interannual variation in the

Change in alcohol outlet density and alcohol-related harm to population health (CHALICE

Directory of Open Access Journals (Sweden)

Fone David

2012-06-01

Full Text Available Abstract Background Excess alcohol consumption has serious adverse effects on health and violence-related harm. In the UK around 37% of men and 29% of women drink to excess and 20% and 13% report binge drinking. The potential impact on population health from a reduction in consumption is considerable. One proposed method to reduce consumption is to reduce availability through controls on alcohol outlet density. In this study we investigate the impact of a change in the density of alcohol outlets on alcohol consumption and alcohol-related harms to health in the community. Methods/Design A natural experiment of the effect of change in outlet density between 2005–09, in Wales, UK; population 2.4 million aged 16 years and over. Data on outlets are held by the 22 local authorities in Wales under The Licensing Act 2003. The study outcomes are change in (1 alcohol consumption using data from annual Welsh Health Surveys, (2 alcohol-related hospital admissions using the Patient Episode Database for Wales, (3 Accident & Emergency department attendances between midnight–6am, and (4 alcohol-related violent crime against the person, using Police data. The data will be anonymously record-linked within the Secure Anonymised Information Linkage Databank at individual and 2001 Census Lower Super Output Area levels. New methods of network analysis will be used to estimate outlet density. Longitudinal statistical analysis will use (1 multilevel ordinal models of consumption and logistic models of admissions and Accident & Emergency attendance as a function of change in individual outlet exposure, adjusting for confounding variables, and (2 spatial models of the change in counts/rates of each outcome measure and outlet density. We will assess the impact on health inequalities and will correct for population migration. Discussion This inter-disciplinary study requires expertise in epidemiology and public health, health informatics, medical statistics

Consistent individual differences and population plasticity in network-derived sociality: An experimental manipulation of density in a gregarious ungulate

Science.gov (United States)

O’Brien, Paul P.; Vander Wal, Eric

2018-01-01

In many taxa, individual social traits appear to be consistent across time and context, thus meeting the criteria for animal personality. How these differences are maintained in response to changes in population density is unknown, particularly in large mammals, such as ungulates. Using a behavioral reaction norm (BRN) framework, we examined how among- and within-individual variation in social connectedness, measured using social network analyses, change as a function of population density. We studied a captive herd of elk (Cervus canadensis) separated into a group of male elk and a group of female elk. Males and females were exposed to three different density treatments and we recorded social associations between individuals with proximity-detecting radio-collars fitted to elk. We constructed social networks using dyadic association data and calculated three social network metrics reflective of social connectedness: eigenvector centrality, graph strength, and degree. Elk exhibited consistent individual differences in social connectedness across densities; however, they showed little individual variation in their response to changes in density, i.e., individuals oftentimes responded plastically, but in the same manner to changes in density. Female elk had highest connectedness at an intermediate density. In contrast, male elk increased connectedness with increasing density. Whereas this may suggest that the benefits of social connectedness outweigh the costs of increased competition at higher density for males, females appear to exhibit a threshold in social benefits (e.g. predator detection and forage information). Our study illustrates the importance of viewing social connectedness as a density-dependent trait, particularly in the context of plasticity. Moreover, we highlight the need to revisit our understanding of density dependence as a population-level phenomenon by accounting for consistent individual differences not only in social connectedness, but likely

Annihilation Radiation Gauge for Relative Density and Multiphase Fluid Monitoring

Directory of Open Access Journals (Sweden)

Vidal A.

2014-03-01

Full Text Available The knowledge of the multi-phase flow parameters are important for the petroleum industry, specifically during the transport in pipelines and network related to exploitation’s wells. Crude oil flow is studied by Monte Carlo simulation and experimentally to determine transient liquid phase in a laboratory system. Relative density and fluid phase time variation is monitored employing a fast nuclear data acquisition setup that includes two large volume BaF2 scintillator detectors coupled to an electronic chain and data display in a LabView® environment. Fluid parameters are determined by the difference in count rate of coincidence pulses. The operational characteristics of the equipment indicate that 2 % deviation in the CCR corresponds to a variation, on average, of 20 % in the fraction of liquid of the multiphase fluid.

Conservation and monitoring of a persecuted African lion population by Maasai warriors.

Science.gov (United States)

Dolrenry, Stephanie; Hazzah, Leela; Frank, Laurence G

2016-06-01

Although Africa has many threatened species and biological hot spots, there are few citizen science schemes, particularly in rural communities, and there has been limited evaluation of existing programs. We engaged traditional Maasai warriors (pastoralist men aged 15 to 35) in community-based conservation and demographic monitoring of a persecuted African lion (Panthera leo) population. Through direct engagement, we investigated whether a citizen science approach employing local warriors, who had no formal education, could produce reliable data on the demographics, predation, and movements of a species with which their communities have been in conflict for generations. Warriors were given benefits such as literacy training and skill enhancement and engaged in the monitoring of the lions. The trained warriors reported on lion sign across an area nearly 4000 km(2) . Scientists worked together with the warriors to verify their reports and gather observations on the lion population. Using the verified reports and collected observations, we examined our scientific knowledge relative to the lion population preceding and during the citizen science program. Our observations showed that data quality and quantity improved with the involvement and training of the participants. Furthermore, because they engaged in conservation and gained personal benefits, the participants came to appreciate a species that was traditionally their foe. We believe engaging other local communities in biodiversity conservation and monitoring may be an effective conservation approach in rural Africa. © 2016 Society for Conservation Biology.

Population density of mediterranean fruit fly (Ceratitis capitata) on fruit orchards in south Baghdad

International Nuclear Information System (INIS)

Khalaf, M. Z.; Shbar, A. K.; Naher, F. H.; Jabo, N. F.; Abdulhamza, B. H.; Abod, R. S.

2012-12-01

In the recent years the mediterranean fruit fly, Ceratitis capitata distributed in the orchards of central Iraq and caused highly economic losses. This study was conducted in orchards in South Baghdad during 2009 and 2010 and made field survey of the insect in four types of orchards (Citrus, Apricot, Figs and Citrus and A mixture of fruit trees) and used for this purpose tephri traps supplied with Q-Lure and dimethyl dichlorovinyl phosphate (DDVP). The present preliminary study has shown that the Mediterranean fruit fly C.capitata has a year round presence in fruit orchards in central Iraq and reached its highest numerical density of the pest in citrus orchards during November and December were 345 and 363 insect / Trap per month in citrus orchards and the least numerical density during of January and February while the highest numerical density of the insect in orchards of orchards of apricot in Mrch 2010, Figs and Citrus in August 2009 and a Mixture of fruit trees in November 2009 were 45, 116, 311 Insect/ trap per month respectively. The population density of the pest was highest beginning 2010 compared with 2009 , but the high temperature degree (46 - o 5 2) in August 2010 caused a decrease in population density of this pest. C.capitata caused highly economic losses in citrus reaching 68, 71, 82% of the Mandarin, Kaki, Apricot fruits respectively. Currently in Iraq no control method to reduce the economic losses caused by this pest except the use of pesticides GF-120. Therefore, results of this study could be of benefit for orcharch owners when applying an integrated program for controlling fruit fly pests. (Author)

Threatened species richness along a Himalayan elevational gradient: quantifying the influences of human population density, range size, and geometric constraints.

Science.gov (United States)

Paudel, Prakash Kumar; Sipos, Jan; Brodie, Jedediah F

2018-02-07

A crucial step in conserving biodiversity is to identify the distributions of threatened species and the factors associated with species threat status. In the biodiversity hotspot of the Himalaya, very little is known about which locations harbour the highest diversity of threatened species and whether diversity of such species is related to area, mid-domain effects (MDE), range size, or human density. In this study, we assessed the drivers of variation in richness of threatened birds, mammals, reptiles, actinopterygii, and amphibians along an elevational gradient in Nepal Himalaya. Although geometric constraints (MDE), species range size, and human population density were significantly related to threatened species richness, the interaction between range size and human population density was of greater importance. Threatened species richness was positively associated with human population density and negatively associated with range size. In areas with high richness of threatened species, species ranges tend to be small. The preponderance of species at risk of extinction at low elevations in the subtropical biodiversity hotspot could be due to the double impact of smaller range sizes and higher human density.

The ideal free distribution as an evolutionarily stable state in density-dependent population games

Czech Academy of Sciences Publication Activity Database

Cressman, R.; Křivan, Vlastimil

2010-01-01

Roč. 119, č. 8 (2010), s. 1231-1242 ISSN 0030-1299 R&D Projects: GA AV ČR IAA100070601 Institutional research plan: CEZ:AV0Z50070508 Keywords : density-dependent population games Subject RIV: EH - Ecology, Behaviour Impact factor: 3.393, year: 2010

On-line monitoring of monoclonal antibody formation in high density perfusion culture using FIA.

Science.gov (United States)

Fenge, C; Fraune, E; Freitag, R; Scheper, T; Schügerl, K

1991-05-01

An automated flow injection system for on-line analysis of proteins in real fermentation fluids was developed by combining the principles of stopped-flow, merging zones flow injection analysis (FIA) with antigen-antibody reactions. IgG in the sample reacted with its corresponding antibody (a-IgG) in the reagent solution. Formation of insoluble immunocomplexes resulted in an increase of the turbidity which was determined photometrically. This system was used to monitor monoclonal antibody production in high cell density perfusion culture of hybridoma cells. Perfusion was performed with a newly developed static filtration unit equipped with hydrophilic microporous tubular membranes. Different sampling devices were tested to obtain a cell-free sample stream for on-line product analysis of high molecular weight (e.g., monoclonal antibodies) and low molecular weight (e.g., glucose, lactate) medium components. In fermentation fluids a good correlation (coefficient: 0.996) between the FIA method and an ELISA test was demonstrated. In a high density perfusion cultivation process mAb formation was successfully monitored on-line over a period of 400 h using a reliable sampling system. Glucose and lactate were measured over the same period of time using a commercially available automatic analyser based on immobilized enzyme technology.

International Consortium on Mammographic Density: Methodology and Population Diversity captured across 22 Countries

Science.gov (United States)

McCormack, Valerie A.; Burton, Anya; dos-Santos-Silva, Isabel; Hipwell, John H.; Dickens, Caroline; Salem, Dorria; Kamal, Rasha; Hartman, Mikael; Ling Lee, Charmaine Pei; Chia, Kee-Seng; Ozmen, Vahit; Aribal, Mustafa Erkin; Flugelman, Anath Arzee; Lajous, Martín; Lopez-Riduara, Ruy; Rice, Megan; Romieu, Isabelle; Ursin, Giske; Qureshi, Samera; Ma, Huiyan; Lee, Eunjung; van Gils, Carla H.; Wanders, Johanna O.P.; Vinayak, Sudhir; Ndumia, Rose; Allen, Steve; Vinnicombe, Sarah; Moss, Sue; Lee, Jong Won; Kim, Jisun; Pereira, Ana; Garmendia, Maria Luisa; Sirous, Reza; Sirous, Mehri; Peplonska, Beata; Bukowska, Agnieszka; Tamimi, Rulla M.; Bertrand, Kimberly; Nagata, Chisato; Kwong, Ava; Vachon, Celine; Scott, Christopher; Perez-Gomez, Beatriz; Pollan, Marina; Maskarinec, Gertraud; Giles, Graham; Hopper, John; Stone, Jennifer; Rajaram, Nadia; Teo, Soo-Hwang; Mariapun, Shivaani; Yaffe, Martin J.; Schüz, Joachim; Chiarelli, Anna; Linton, Linda; Boyd, Norman F.

2015-01-01

Mammographic density (MD) is a quantitative trait, measurable in all women, and is among the strongest markers of breast cancer risk. The population-based epidemiology of MD has revealed genetic, lifestyle and societal/environmental determinants, but studies have largely been conducted in women with similar westernized lifestyles living in countries with high breast cancer incidence rates. To benefit from the heterogeneity in risk factors and their combinations worldwide, we created an International Consortium on Mammographic Density (ICMD) to pool individual-level epidemiological and MD data from general population studies worldwide. ICMD aims to characterize determinants of MD more precisely, and to evaluate whether they are consistent across populations worldwide. We included 11755 women, from 27 studies in 22 countries, on whom individual-level risk factor data were pooled and original mammographic images were re-read for ICMD by a core team to obtain standardized comparable MD data. In the present article, we present (i) the rationale for this consortium; (ii) characteristics of the studies and women included; and (iii) study methodology to obtain comparable MD data from original re-read films. We also highlight the risk factor heterogeneity captured by such an effort and, thus, the unique insight the pooled study promises to offer through wider exposure ranges, different confounding structures and enhanced power for sub-group analyses. PMID:26724463

Effects of demographic structure on key properties of stochastic density-independent population dynamics.

Science.gov (United States)

Vindenes, Yngvild; Sæther, Bernt-Erik; Engen, Steinar

2012-12-01

The development of stochastic demography has largely been based on age structured populations, although other types of demographic structure, especially permanent and dynamic heterogeneity, are likely common in natural populations. The combination of stochasticity and demographic structure is a challenge for analyses of population dynamics and extinction risk, because the population structure will fluctuate around the stable structure and the population size shows transient fluctuations. However, by using a diffusion approximation for the total reproductive value, density-independent dynamics of structured populations can be described with only three population parameters: the expected population growth rate, the environmental variance and the demographic variance. These parameters depend on population structure via the state-specific vital rates and transition rates. Once they are found, the diffusion approximation represents a substantial reduction in model complexity. Here, we review and compare the key population parameters across a wide range of demographic structure, from the case of no structure to the most general case of dynamic heterogeneity, and for both discrete and continuous types. We focus on the demographic variance, but also show how environmental stochasticity can be included. This study brings together results from recent models, each considering a specific type of population structure, and places them in a general framework for structured populations. Comparison across different types of demographic structure reveals that the reproductive value is an essential concept for understanding how population structure affects stochastic dynamics and extinction risk. Copyright © 2011 Elsevier Inc. All rights reserved.

POLAMI: Polarimetric Monitoring of Active Galactic Nuclei at Millimetre Wavelengths - III. Characterization of total flux density and polarization variability of relativistic jets

Science.gov (United States)

Agudo, Iván; Thum, Clemens; Ramakrishnan, Venkatessh; Molina, Sol N.; Casadio, Carolina; Gómez, José L.

2018-01-01

We report on the first results of the POLAMI (Polarimetric Monitoring of AGNs with Millimetre Wavelengths) programme, a simultaneous 3.5 and 1.3 mm full-Stokes-polarization monitoring of a sample of 36 of the brightest active galactic nuclei in the northern sky with the IRAM 30 m telescope. Through a systematic statistical study of data taken from 2006 October (from 2009 December for the case of the 1.3 mm observations) to 2014 August, we characterize the variability of the total flux density and linear polarization. We find that all sources in the sample are highly variable in total flux density at both 3.5 and 1.3 mm, as well as in spectral index, which (except in particularly prominent flares) is found to be optically thin between these two wavelengths. The total flux-density variability at 1.3 mm is found, in general, to be faster, and to have larger fractional amplitude and flatter power-spectral-density slopes than at 3.5 mm. The polarization degree is on average larger at 1.3 mm than at 3.5 mm, by a factor of 2.6. The variability of linear polarization degree is faster and has higher fractional amplitude than for total flux density, with the typical time-scales during prominent polarization peaks being significantly faster at 1.3 mm than at 3.5 mm. The polarization angle at both 3.5 and 1.3 mm is highly variable. Most of the sources show one or two excursions of >180° on time-scales from a few weeks to about a year during the course of our observations. The 3.5 and 1.3 mm polarization angle evolution follows each other rather well, although the 1.3 mm data show a clear preference to more prominent variability on the short time-scales, i.e. weeks. The data are compatible with multizone models of conical jets involving smaller emission regions for the shortest-wavelength emitting sites. Such smaller emitting regions should also be more efficient in energising particle populations, as implied by the coherent evolution of the spectral index and the total flux

Efficacy of passive hair-traps for the genetic sampling of a low-density badger population

Directory of Open Access Journals (Sweden)

Alessandro Balestrieri

2011-02-01

Full Text Available

A hair-trapping survey was carried out in the western River Po plain (NW Italy. We aimed to test whether barbed wire hair snares in combination with DNA profiling might represent an effective tool to study a low-density badger population. Traps were placed above the entrances of twelve badger setts between 15 February and 30 April 2010. Trapping effort was expressed as the number of trap-nights required to pluck a hair sample and the trend in the number of genotyped individual over time was analysed by regression analysis. Forty-three hair samples were collected, with an overall trapping effort of 54.8 trap-nights per one hair sample. Twenty-eight samples yielded reliable genotypes, allowing the identification of nine individual badgers. The length of storage period (1-3 months before DNA extraction did not seem to affect genotyping success. According to the regression model, trapping effort allowed to sample 75% of the overall population. Our results suggest that the efficacy of passive devices is affected by population density.

Increase in Population Density and Aggravation of Social and Psychological Problems in Areas with High-Rise Construction

Directory of Open Access Journals (Sweden)

Romanova Elena

2018-01-01

Full Text Available High-rise apartment houses have technical and economic advantages in areas with dense population. Their placement in the central part of the city allows increasing the number of living space in the limited territory, to bring population to the place of employment and reduce pendular migration. But increase in population density leads to psychological problems: level of a stress, fatigue increases, the number of phobias grows, infectious diseases extend quicker. These problems can be solved at resettlement of inhabitants to the suburb. However such decision leads to aggravation of a transport problem and the pulsing increase in population density in the downtown and on its suburb. To solve a transport problem, it is necessary not to increase the square of the cities. Therefore in the suburbs is also used high-rise construction. But high-rise residential districts on the suburb of the city get own social problems which are capable to destroy all advantages of high-rise construction.

Increase in Population Density and Aggravation of Social and Psychological Problems in Areas with High-Rise Construction

Science.gov (United States)

Romanova, Elena

2018-03-01

High-rise apartment houses have technical and economic advantages in areas with dense population. Their placement in the central part of the city allows increasing the number of living space in the limited territory, to bring population to the place of employment and reduce pendular migration. But increase in population density leads to psychological problems: level of a stress, fatigue increases, the number of phobias grows, infectious diseases extend quicker. These problems can be solved at resettlement of inhabitants to the suburb. However such decision leads to aggravation of a transport problem and the pulsing increase in population density in the downtown and on its suburb. To solve a transport problem, it is necessary not to increase the square of the cities. Therefore in the suburbs is also used high-rise construction. But high-rise residential districts on the suburb of the city get own social problems which are capable to destroy all advantages of high-rise construction.

Monitoring techniques of the western corn rootworm are the precursor to effective IPM strategies.

Science.gov (United States)

Lemic, Darija; Mikac, Katarina M; Kozina, Antonela; Benitez, Hugo A; McLean, Christopher M; Bažok, Renata

2016-02-01

The western corn rootworm (WCR) is economically the most important pest of maize in Croatia. To predict WCR adult population abundance and variability, traditional, genetic and morphometric monitoring of populations was conducted over time through each phase of the WCR invasion process in Croatia. Through traditional monitoring it was shown that WCR established their current population and reached economic densities after 14 years persisting in the study area. Regression-tree-based modelling showed that the best predictor of WCR adult abundance was the total amount of rainfall. Genetic monitoring indicated that genetic differentiation increased over time at the intrapopulation level, and morphometric monitoring indicated that wing morphotypes varied according to edaphic landscape changes. Traditional population metric surveys are important in WCR integrated pest management (IPM), as such surveys can be effectively used to predict population abundances. Novel-use monitoring techniques such as genetics and geometric morphometrics can be used to provide valuable information on variation within and among populations. The monitoring techniques presented herein provide sound data to assist in the understanding of both WCR ecology and population genetics and may provide more information than that currently available using traditional techniques (e.g. sticky traps), and as such these additional techniques should be written into IPM for WCR. © 2015 Society of Chemical Industry.

Increased population density of neurosurgeons associated with decreased risk of death from motor vehicle accidents in the United States.

Science.gov (United States)

Desai, Atman; Bekelis, Kimon; Zhao, Wenyan; Ball, Perry A

2012-09-01

Motor vehicle accidents (MVAs) are a leading cause of death and disability in young people. Given that a major cause of death from MVAs is traumatic brain injury, and neurosurgeons hold special expertise in this area relative to other members of a trauma team, the authors hypothesized that neurosurgeon population density would be related to reduced mortality from MVAs across US counties. The Area Resource File (2009-2010), a national health resource information database, was retrospectively analyzed. The primary outcome variable was the 3-year (2004-2006) average in MVA deaths per million population for each county. The primary independent variable was the density of neurosurgeons per million population in the year 2006. Multiple regression analysis was performed, adjusting for population density of general practitioners, urbanicity of the county, and socioeconomic status of the county. The median number of annual MVA deaths per million population, in the 3141 counties analyzed, was 226 (interquartile range [IQR] 151-323). The median number of neurosurgeons per million population was 0 (IQR 0-0), while the median number of general practitioners per million population was 274 (IQR 175-410). Using an unadjusted analysis, each increase of 1 neurosurgeon per million population was associated with 1.90 fewer MVA deaths per million population (p neurosurgeon per million population was associated with 1.01 fewer MVA deaths per million population (p neurosurgeons is associated with a significant reduction in deaths from MVAs, a major cause of death nationally. This suggests that the availability of local neurosurgeons is an important factor in the overall likelihood of survival from an MVA, and therefore indicates the importance of promoting neurosurgical education and practice throughout the country.

What does the fox say? Monitoring antimicrobial resistance in the environment using wild red foxes as an indicator.

Directory of Open Access Journals (Sweden)

Solveig Sølverød Mo

Full Text Available The objective of this study was to estimate and compare the occurrence of AMR in wild red foxes in relation to human population densities. Samples from wild red foxes (n = 528 included in the Norwegian monitoring programme on antimicrobial resistance in bacteria from food, feed and animals were included. All samples were divided into three different groups based on population density in the municipality where the foxes were hunted. Of the 528 samples included, 108 (20.5%, 328 (62.1% and 92 (17.4% originated from areas with low, medium and high population density, respectively. A single faecal swab was collected from each fox. All samples were plated out on a selective medium for Enterobacteriaceae for culturing followed by inclusion and susceptibility testing of one randomly selected Escherichia coli to assess the overall occurrence of AMR in the Gram-negative bacterial population. Furthermore, the samples were subjected to selective screening for detection of E. coli displaying resistance towards extended-spectrum cephalosporins and fluoroquinolones. In addition, a subset of samples (n = 387 were subjected to selective culturing to detect E. coli resistant to carbapenems and colistin, and enterococci resistant to vancomycin. Of these, 98 (25.3%, 200 (51.7% and 89 (23.0% originated from areas with low, medium and high population density, respectively. Overall, the occurrence of AMR in indicator E. coli from wild red foxes originating from areas with different human population densities in Norway was low to moderate (8.8%. The total occurrence of AMR was significantly higher; χ2 (1,N = 336 = 6.53, p = 0.01 in areas with high population density compared to areas with medium population density. Similarly, the occurrence of fluoroquinolone resistant E. coli isolated using selective detection methods was low in areas with low population density and more common in areas with medium or high population density. In conclusion, we found indications that

Integration of Density Dependence and Concentration Response Models Provides an Ecologically Relevant Assessment of Populations Exposed to Toxicants

Science.gov (United States)

The assessment of toxic exposure on wildlife populations involves the integration of organism level effects measured in toxicity tests (e.g., chronic life cycle) and population models. These modeling exercises typically ignore density dependence, primarily because information on ...

A macroevolutionary explanation for energy equivalence in the scaling of body size and population density.

Science.gov (United States)

Damuth, John

2007-05-01

Across a wide array of animal species, mean population densities decline with species body mass such that the rate of energy use of local populations is approximately independent of body size. This "energetic equivalence" is particularly evident when ecological population densities are plotted across several or more orders of magnitude in body mass and is supported by a considerable body of evidence. Nevertheless, interpretation of the data has remained controversial, largely because of the difficulty of explaining the origin and maintenance of such a size-abundance relationship in terms of purely ecological processes. Here I describe results of a simulation model suggesting that an extremely simple mechanism operating over evolutionary time can explain the major features of the empirical data. The model specifies only the size scaling of metabolism and a process where randomly chosen species evolve to take resource energy from other species. This process of energy exchange among particular species is distinct from a random walk of species abundances and creates a situation in which species populations using relatively low amounts of energy at any body size have an elevated extinction risk. Selective extinction of such species rapidly drives size-abundance allometry in faunas toward approximate energetic equivalence and maintains it there.

Sample size for monitoring sirex populations and their natural enemies

Directory of Open Access Journals (Sweden)

Susete do Rocio Chiarello Penteado

2016-09-01

Full Text Available The woodwasp Sirex noctilio Fabricius (Hymenoptera: Siricidae was introduced in Brazil in 1988 and became the main pest in pine plantations. It has spread to about 1.000.000 ha, at different population levels, in the states of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo and Minas Gerais. Control is done mainly by using a nematode, Deladenus siricidicola Bedding (Nematoda: Neothylenchidae. The evaluation of the efficiency of natural enemies has been difficult because there are no appropriate sampling systems. This study tested a hierarchical sampling system to define the sample size to monitor the S. noctilio population and the efficiency of their natural enemies, which was found to be perfectly adequate.

Multiple estimates of effective population size for monitoring a long-lived vertebrate: An application to Yellowstone grizzly bears

Science.gov (United States)

Kamath, Pauline L.; Haroldson, Mark A.; Luikart, Gordon; Paetkau, David; Whitman, Craig L.; van Manen, Frank T.

2015-01-01

Effective population size (Ne) is a key parameter for monitoring the genetic health of threatened populations because it reflects a population's evolutionary potential and risk of extinction due to genetic stochasticity. However, its application to wildlife monitoring has been limited because it is difficult to measure in natural populations. The isolated and well-studied population of grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem provides a rare opportunity to examine the usefulness of different Ne estimators for monitoring. We genotyped 729 Yellowstone grizzly bears using 20 microsatellites and applied three single-sample estimators to examine contemporary trends in generation interval (GI), effective number of breeders (Nb) and Ne during 1982–2007. We also used multisample methods to estimate variance (NeV) and inbreeding Ne (NeI). Single-sample estimates revealed positive trajectories, with over a fourfold increase in Ne (≈100 to 450) and near doubling of the GI (≈8 to 14) from the 1980s to 2000s. NeV (240–319) and NeI (256) were comparable with the harmonic mean single-sample Ne (213) over the time period. Reanalysing historical data, we found NeV increased from ≈80 in the 1910s–1960s to ≈280 in the contemporary population. The estimated ratio of effective to total census size (Ne/Nc) was stable and high (0.42–0.66) compared to previous brown bear studies. These results support independent demographic evidence for Yellowstone grizzly bear population growth since the 1980s. They further demonstrate how genetic monitoring of Ne can complement demographic-based monitoring of Nc and vital rates, providing a valuable tool for wildlife managers.

The landscape configuration of zoonotic transmission of Ebola virus disease in West and Central Africa: interaction between population density and vegetation cover

Directory of Open Access Journals (Sweden)

Michael G. Walsh

2015-01-01

Full Text Available Ebola virus disease (EVD is an emerging infectious disease of zoonotic origin that has been responsible for high mortality and significant social disruption in West and Central Africa. Zoonotic transmission of EVD requires contact between susceptible human hosts and the reservoir species for Ebolaviruses, which are believed to be fruit bats. Nevertheless, features of the landscape that may facilitate such points of contact have not yet been adequately identified. Nor have spatial dependencies between zoonotic EVD transmission and landscape structures been delineated. This investigation sought to describe the spatial relationship between zoonotic EVD transmission events, or spillovers, and population density and vegetation cover. An inhomogeneous Poisson process model was fitted to all precisely geolocated zoonotic transmissions of EVD in West and Central Africa. Population density was strongly associated with spillover; however, there was significant interaction between population density and green vegetation cover. In areas of very low population density, increasing vegetation cover was associated with a decrease in risk of zoonotic transmission, but as population density increased in a given area, increasing vegetation cover was associated with increased risk of zoonotic transmission. This study showed that the spatial dependencies of Ebolavirus spillover were associated with the distribution of population density and vegetation cover in the landscape, even after controlling for climate and altitude. While this is an observational study, and thus precludes direct causal inference, the findings do highlight areas that may be at risk for zoonotic EVD transmission based on the spatial configuration of important features of the landscape.

Browsing Patterns of White-Tailed Deer Following Increased Timber Harvest and a Decline in Population Density

Directory of Open Access Journals (Sweden)

Shawn M. Crimmins

2010-01-01

Full Text Available We examined browsing patterns of white-tailed deer (Odocoileus virginianus on a site in the central Appalachians that experienced a substantial (>50% reduction in deer population density and an increase in the amount of timber harvest since 2001. We sampled woody browse in and immediately adjacent to 12 clearcuts ranging in age from 0–5 years postharvest in summer 2007. Clearcut-interior areas had higher woody browse abundance and browsing rates than clearcut-edge or mature forest areas. Woody browse abundance was slightly higher within individual clearcuts than in 2001 at higher population densities and lower timber harvest rates. Overall browsing rates declined from approximately 17% in 2001 to less than 5% during our study, suggesting that the combination of deer population control, and increasing the amount of timber harvest across the landscape can reduce herbivory to levels that may not impede growth and survival of forest vegetation.

Characterization of oscillator circuits for monitoring the density-viscosity of liquids by means of piezoelectric MEMS microresonators

Science.gov (United States)

Toledo, J.; Ruiz-Díez, V.; Pfusterschmied, G.; Schmid, U.; Sánchez-Rojas, J. L.

2017-06-01

Real-time monitoring of the physical properties of liquids, such as lubricants, is a very important issue for the automotive industry. For example, contamination of lubricating oil by diesel soot has a significant impact on engine wear. Resonant microstructures are regarded as a precise and compact solution for tracking the viscosity and density of lubricant oils. In this work, we report a piezoelectric resonator, designed to resonate with the 4th order out-of-plane modal vibration, 15-mode, and the interface circuit and calibration process for the monitoring of oil dilution with diesel fuel. In order to determine the resonance parameters of interest, i.e. resonant frequency and quality factor, an interface circuit was implemented and included within a closed-loop scheme. Two types of oscillator circuits were tested, a Phase-Locked Loop based on instrumentation, and a more compact version based on discrete electronics, showing similar resolution. Another objective of this work is the assessment of a calibration method for piezoelectric MEMS resonators in simultaneous density and viscosity sensing. An advanced calibration model, based on a Taylor series of the hydrodynamic function, was established as a suitable method for determining the density and viscosity with the lowest calibration error. Our results demonstrate the performance of the resonator in different oil samples with viscosities up to 90 mPa•s. At the highest value, the quality factor measured at 25°C was around 22. The best resolution obtained was 2.4•10-6 g/ml for the density and 2.7•10-3 mPa•s for the viscosity, in pure lubricant oil SAE 0W30 at 90°C. Furthermore, the estimated density and viscosity values with the MEMS resonator were compared to those obtained with a commercial density-viscosity meter, reaching a mean calibration error in the best scenario of around 0.08% for the density and 3.8% for the viscosity.

High population density of Little Owl (Athene noctua) in Hortobagy National Park, Hungary, Central Europe

Czech Academy of Sciences Publication Activity Database

Šálek, Martin; Chrenková, M.; Kipson, M.

2013-01-01

Roč. 61, č. 1 (2013), s. 165-169 ISSN 1505-2249 Institutional support: RVO:68081766 Keywords : Little Owl * population density * distribution * breeding places * Hortobagy National Park * Hungary Subject RIV: EH - Ecology, Behaviour Impact factor: 0.554, year: 2013

Line-Trapping of Codling Moth (Lepidoptera: Tortricidae): A Novel Approach to Improving the Precision of Capture Numbers in Traps Monitoring Pest Density.

Science.gov (United States)

Adams, C G; McGhee, P S; Schenker, J H; Gut, L J; Miller, J R

2017-08-01

This field study of codling moth, Cydia pomonella (L.), response to single versus multiple monitoring traps baited with codlemone demonstrates that precision of a given capture number is alarmingly poor when the population is held constant by releasing moths. Captures as low as zero and as high as 12 males per single trap are to be expected where the catch mode is three. Here, we demonstrate that the frequency of false negatives and overestimated positives for codling moth trapping can be substantially reduced by employing the tactic of line-trapping, where five traps were deployed 4 m apart along a row of apple trees. Codling moth traps spaced closely competed only slightly. Therefore, deploying five traps closely in a line is a sampling technique nearly as good as deploying five traps spaced widely. But line trapping offers a substantial savings in time and therefore cost when servicing aggregated versus distributed traps. As the science of pest management matures by mastering the ability to translate capture numbers into estimates of absolute pest density, it will be important to employ a tactic like line-trapping so as to shrink the troublesome variability associated with capture numbers in single traps that thwarts accurate decisions about if and when to spray. Line-trapping might similarly increase the reliability and utility of density estimates derived from capture numbers in monitoring traps for various pest and beneficial insects. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Neighbourhood density and genetic relatedness interact to determine fruit set and abortion rates in a continuous tropical tree population.

Science.gov (United States)

Jones, F A; Comita, L S

2008-12-07

Tropical trees may show positive density dependence in fruit set and maturation due to pollen limitation in low-density populations. However, pollen from closely related individuals in the local neighbourhood might reduce fruit set or increase fruit abortion in self-incompatible tree species. We investigated the role of neighbourhood density and genetic relatedness on individual fruit set and abortion in the neotropical tree Jacaranda copaia in a large forest plot in central Panama. Using nested neighbourhood models, we found a strong positive effect of increased conspecific density on fruit set and maturation. However, high neighbourhood genetic relatedness interacted with density to reduce total fruit set and increase the proportion of aborted fruit. Our results imply a fitness advantage for individuals growing in high densities as measured by fruit set, but realized fruit set is lowered by increased neighbourhood relatedness. We hypothesize that the mechanism involved is increased visitation by density-dependent invertebrate pollinators in high-density populations, which increases pollen quantity and carry-over and increases fruit set and maturation, coupled with self-incompatibility at early and late stages due to biparental inbreeding that lowers fruit set and increases fruit abortion. Implications for the reproductive ecology and conservation of tropical tree communities in continuous and fragmented habitats are discussed.

Coral reef degradation is not correlated with local human population density

Science.gov (United States)

Bruno, John F.; Valdivia, Abel

2016-07-01

The global decline of reef-building corals is understood to be due to a combination of local and global stressors. However, many reef scientists assume that local factors predominate and that isolated reefs, far from human activities, are generally healthier and more resilient. Here we show that coral reef degradation is not correlated with human population density. This suggests that local factors such as fishing and pollution are having minimal effects or that their impacts are masked by global drivers such as ocean warming. Our results also suggest that the effects of local and global stressors are antagonistic, rather than synergistic as widely assumed. These findings indicate that local management alone cannot restore coral populations or increase the resilience of reefs to large-scale impacts. They also highlight the truly global reach of anthropogenic warming and the immediate need for drastic and sustained cuts in carbon emissions.

Evidence for Reciprocal Selection between Populations of Meloidogyne arenaria and Pasteuria penetrans in a Field Study

Science.gov (United States)

Beginning in 1998, a bioassay using second-stage juveniles (J2) from a greenhouse (GH) population of Meloidogyne arenaria (Ma) was used to monitor endospore densities of the bacterium Pasteuria penetrans, which was parasitizing Ma in a crop rotation study. Spore densities of the bacterium were very...

Population estimates and monitoring guidelines for endangered Laysan Teal, Anas Laysanensis, at Midway Atoll: Pilot study results 2008-2010.

Science.gov (United States)

Reynolds, Michelle H.; Brinck, Kevin W.; Laniawe, Leona

2011-01-01

Accurate estimates of population size are often crucial to determining status and planning recovery of endangered species. The ability to detect trends in survival and population size over time enables conservation managers to make effective decisions for species and refuge management. During 2004–2007, the translocated population of endangered Laysan Teal (Anas laysanensis; also Laysan Duck) was fitted with radio transmitters providing known (―gold standard‖) measures of survival and reproduction. However, as the population grew, statistically rigorous monitoring protocols were needed that were less labor intensive than radio telemetry. A population die-off and alarmingly high number of carcasses (181) were recorded during a botulism epizootic in August–October 2008, which further reinforced the need for effective monitoring protocols since this endangered species is vulnerable to catastrophic population declines. In fall 2008, we initiated a pilot study using standardized surveys with uniquely marked birds to monitor abundance and estimate the population growth rate of the reintroduced Laysan Teal. Since few birds carried marks (leg bands) after the 2008 botulism die-off (only about 15% of the population), and standardized surveys were not yet implemented, the magnitude of the die-off on the population size was unknown.

Multiple estimates of effective population size for monitoring a long-lived vertebrate: an application to Yellowstone grizzly bears.

Science.gov (United States)

Kamath, Pauline L; Haroldson, Mark A; Luikart, Gordon; Paetkau, David; Whitman, Craig; van Manen, Frank T

2015-11-01

Effective population size (N(e)) is a key parameter for monitoring the genetic health of threatened populations because it reflects a population's evolutionary potential and risk of extinction due to genetic stochasticity. However, its application to wildlife monitoring has been limited because it is difficult to measure in natural populations. The isolated and well-studied population of grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem provides a rare opportunity to examine the usefulness of different N(e) estimators for monitoring. We genotyped 729 Yellowstone grizzly bears using 20 microsatellites and applied three single-sample estimators to examine contemporary trends in generation interval (GI), effective number of breeders (N(b)) and N(e) during 1982-2007. We also used multisample methods to estimate variance (N(eV)) and inbreeding N(e) (N(eI)). Single-sample estimates revealed positive trajectories, with over a fourfold increase in N(e) (≈100 to 450) and near doubling of the GI (≈8 to 14) from the 1980s to 2000s. N(eV) (240-319) and N(eI) (256) were comparable with the harmonic mean single-sample N(e) (213) over the time period. Reanalysing historical data, we found N(eV) increased from ≈80 in the 1910s-1960s to ≈280 in the contemporary population. The estimated ratio of effective to total census size (N(e) /N(c)) was stable and high (0.42-0.66) compared to previous brown bear studies. These results support independent demographic evidence for Yellowstone grizzly bear population growth since the 1980s. They further demonstrate how genetic monitoring of N(e) can complement demographic-based monitoring of N(c) and vital rates, providing a valuable tool for wildlife managers. © 2015 John Wiley & Sons Ltd.

Population density of Sotalia guianensis (Cetacea: Delphinidae in the Cananéia region, Southeastern Brazil

Directory of Open Access Journals (Sweden)

Liisa Havukainen

2011-09-01

Full Text Available Population density in cetaceans can be estimated through photo-identification, mark-recapture, land-based observations and visual estimative. We the aim to contribute with conservation strategies, we used line transects (distance method to estimate the population density of the river dolphin, S. guianensis, in the estuarine region of Cananéia, Southeastern Brazil. The study, developed from May 2003 until April 2004, during dry and rainy seasons and different times of the day, included a sampling area divided into three sectors according to their proximity to the open sea: Sector I (the closest to the open sea; Sector II (with a large flow of fresh water and a salient declivity; and Sector III (with a large flow of fresh water and non salient declivity. Onboard random sampling was carried out in all three sectors, and dolphins seen from the bow to 90° on both port and starboard sides, were registered along with their position and distance from the boat. The total density found was 12.41ind/km² (CV=25.53% with an average of 2.2 individuals per group for both periods of the day, morning and afternoon. Densities also varied between dry and rainy seasons, being lower in the first with 5.77ind/km² (CV=27.87% than in the second 20.28ind/km² (CV=31.95%, respectively. Regarding the three sectors, a non-causal heterogeneous distribution was found: Sector I was the most populated (D=33.10ind/km², CV=13.34%, followed by Sector II (D=7.8ind/km², CV=21.07% and Sector III (D=3.04ind/km², CV=34.04%. The aforementioned area, due to its proximity to the open sea, has the highest salinity level and therefore has the greatest chance of holding most of the marine fish schools which can be cornered by dolphins on high declivity areas during fishing activities. This suggests that food availability may be the most important factor on the river dolphin’s distribution in the estuary. Similar studies will contribute to a better understanding of these populations

Inferring cetacean population densities from the absolute dynamic topography of the ocean in a hierarchical Bayesian framework.

Directory of Open Access Journals (Sweden)

Mario A Pardo

Full Text Available We inferred the population densities of blue whales (Balaenoptera musculus and short-beaked common dolphins (Delphinus delphis in the Northeast Pacific Ocean as functions of the water-column's physical structure by implementing hierarchical models in a Bayesian framework. This approach allowed us to propagate the uncertainty of the field observations into the inference of species-habitat relationships and to generate spatially explicit population density predictions with reduced effects of sampling heterogeneity. Our hypothesis was that the large-scale spatial distributions of these two cetacean species respond primarily to ecological processes resulting from shoaling and outcropping of the pycnocline in regions of wind-forced upwelling and eddy-like circulation. Physically, these processes affect the thermodynamic balance of the water column, decreasing its volume and thus the height of the absolute dynamic topography (ADT. Biologically, they lead to elevated primary productivity and persistent aggregation of low-trophic-level prey. Unlike other remotely sensed variables, ADT provides information about the structure of the entire water column and it is also routinely measured at high spatial-temporal resolution by satellite altimeters with uniform global coverage. Our models provide spatially explicit population density predictions for both species, even in areas where the pycnocline shoals but does not outcrop (e.g. the Costa Rica Dome and the North Equatorial Countercurrent thermocline ridge. Interannual variations in distribution during El Niño anomalies suggest that the population density of both species decreases dramatically in the Equatorial Cold Tongue and the Costa Rica Dome, and that their distributions retract to particular areas that remain productive, such as the more oceanic waters in the central California Current System, the northern Gulf of California, the North Equatorial Countercurrent thermocline ridge, and the more

Spatial relationship between human population density, land use intensity and biodiversity in the Czech Republic

Czech Academy of Sciences Publication Activity Database

Vačkář, David; Chobot, K.; Orlitová, E.

2012-01-01

Roč. 27, č. 9 (2012), s. 1279-1290 ISSN 0921-2973 Institutional support: RVO:67179843 Keywords : species richness * landscape diversity * human population density * human appropriation of net primary production * Czech Republic Subject RIV: EH - Ecology, Behaviour Impact factor: 2.897, year: 2012

Genetic Variation and Phenotypic Response of 15 Sweet Corn (Zea mays L. Hybrids to Population Density

Directory of Open Access Journals (Sweden)

William F. Tracy

2013-06-01

Full Text Available Planting sweet corn at higher densities may increase the canopy cover, reducing light transmission to the understory and suppressing weed growth. High planting densities can also negatively impact the crop, however, by decreasing ear size and overall yield. The objective of this study was to determine the potential for increased density tolerance of 15 sweet corn hybrids by estimating the general combining ability (GCA and specific combining ability (SCA for traits of interest. In 2010 and 2011, a half-diallel of six historic sweet corn inbreds was evaluated in a split-block randomized complete block design in four Wisconsin environments, with four replicates in each environment. Hybrids were planted at a low density of 29,936 plants ha−1, a medium density of 63,615 plants ha−1, and a high density of 97,293 plants ha−1. Significant differences between hybrids were found for phenomorphological traits and ear characteristics. Inbreds C68, C40 and Ia5125 produced the progeny most tolerant of the highest population density. Among these genotypes, tolerance to high density is a heritable trait, indicating the feasibility of breeding sweet corn for density tolerance and potential weed competitiveness.

Effects of larval population density on rates of development and interactions between two species of Chrysomya (Diptera: Calliphoridae) in laboratory culture.

Science.gov (United States)

Goodbrod, J R; Goff, M L

1990-05-01

Rearing of Chrysomya megacephala (F.) and Chrysomya rufifacies (Macquart) in pure cultures at seven different population densities (larvae per gram of liver) demonstrated an inverse relationship between density and the duration of the larval stage. In pure cultures, larval mortality rates decreased with increasing density until an optimum density was reached (8 larvae/g liver for C. megacephala and 10 larvae/g liver for C. rufifacies), then decreased directly with density. Puparial and adult weights varied inversely with density for both species in pure cultures. Internal feeding mass temperatures were above ambient temperatures for all cultures, with maximum temperatures recorded in cultures with 20 and 40 larvae/g liver for G. rufifacies and C. megacephala, respectively. In paired encounters, larvae of C. rufifacies were cannibalistic and predatory on C. megacephala larvae after the first instar. In mixed cultures of these two species, the larval mortality of C. rufifacies remained relatively stable, whereas the larval mortality of C. megacephala increased directly with population density.

Escape from the competence state in Streptococcus mutans is governed by the bacterial population density.

Science.gov (United States)

Dufour, D; Villemin, C; Perry, J A; Lévesque, C M

2016-12-01

Horizontal gene transfer through natural DNA transformation is an important evolutionary mechanism among bacteria. Transformation requires that the bacteria are physiologically competent to take and incorporate free DNA directly from the environment. Although natural genetic transformation is a remarkable feature of many naturally competent bacteria, the process is energetically expensive for the cells. Consequently, a tight control of the competence state is necessary. The objective of the present work was to help decipher the molecular mechanisms regulating the escape from the competence state in Streptococcus mutans, the principal etiological agent responsible for tooth decay in humans. Our results showed that the cessation of competence in S. mutans was abrupt, and did not involve the accumulation of a competence inhibitor nor the depletion of a competence activator in the extracellular environment. The competence state was repressed at high cell population density via concomitant repression of sigX gene encoding the master regulator of the competence regulon. Co-culture experiments performed with oral and non-oral bacteria showed that S. mutans assesses its own population density and also the microbial density of its surroundings to regulate its competence escape. Interestingly, neither the intra-species and extra-species quorum-sensing systems nor the other 13 two-component regulatory systems identified in S. mutans were involved in the cell-density-dependent escape of the competence state. Altogether, our results suggest a complex mechanism regulating the competence shut-off involving cell-density-dependent repression of sigX through an as yet undefined system, and possibly SigX protein stability. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Unique Features of High-Density Lipoproteins in the Japanese: In Population and in Genetic Factors

Directory of Open Access Journals (Sweden)

Shinji Yokoyama

2015-04-01

Full Text Available Despite its gradual increase in the past several decades, the prevalence of atherosclerotic vascular disease is low in Japan. This is largely attributed to difference in lifestyle, especially food and dietary habits, and it may be reflected in certain clinical parameters. Plasma high-density lipoprotein (HDL levels, a strong counter risk for atherosclerosis, are indeed high among the Japanese. Accordingly, lower HDL seems to contribute more to the development of coronary heart disease (CHD than an increase in non-HDL lipoproteins at a population level in Japan. Interestingly, average HDL levels in Japan have increased further in the past two decades, and are markedly higher than in Western populations. The reasons and consequences for public health of this increase are still unknown. Simulation for the efficacy of raising HDL cholesterol predicts a decrease in CHD of 70% in Japan, greater than the extent by reducing low-density lipoprotein cholesterol predicted by simulation or achieved in a statin trial. On the other hand, a substantial portion of hyperalphalipoproteinemic population in Japan is accounted for by genetic deficiency of cholesteryl ester transfer protein (CETP, which is also commonly unique in East Asian populations. It is still controversial whether CETP mutations are antiatherogenic. Hepatic Schistosomiasis is proposed as a potential screening factor for historic accumulation of CETP deficiency in East Asia.

Genetic monitoring of western corn rootworm (Coleoptera: Chrysomelidae) populations on a microgeographic scale.

Science.gov (United States)

Ivkosic, S A; Gorman, J; Lemic, D; Mikac, K M

2014-06-01

Microsatellite and mitochondrial DNA genetic monitoring of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was undertaken in Croatia and Serbia from 1996 to 2011 and in the United States in 2011. The seven U.S. populations displayed the greatest allelic diversity. In Europe, the highest number of alleles was found in Rugvica, Croatia, and Surčin, Serbia, the two sites closest to international airports. The highest number of mitochondrial (mt) DNA haplotypes was recorded from Croatia in 1996. From 2009 to 2011, haplotype diversity declined, and Croatia and Serbia had a single fixed haplotype. U.S. continuous maize locations had one haplotype, while three haplotypes were found at crop-rotated locations. Minimal temporal genetic differentiation was found within and between populations in Europe and the United States. Bayesian cluster analysis identified two genetic clusters that grouped western corn rootworm from Croatia and Serbia separately from U.S. populations; however, these clusters were not neat, and numerous U.S. individuals had both European and U.S. ancestry, suggesting bidirectional gene flow. Bottlenecks were identified within most Croatian populations sampled in 1996, only two populations in 2009, and in all populations in 2011. Bottlenecks were not identified from Serbia from 1996 to 2011 or from the United States in 2011. As suspected Serbia was identified as the geographic source of western corn rootworm in Croatia. The temporal genetic monitoring undertaken allowed a deeper understanding of the population genetics of western corn rootworm in Croatia, neighboring Serbia, and its geographic source in the United States. The data obtained can be used to inform western corn rootworm pest management strategies in Croatia and Europe.

Establishing an air pollution monitoring network for intra-urban population exposure assessment : a location-allocation approach

Energy Technology Data Exchange (ETDEWEB)

Kanaroglou, P.S. [McMaster Univ., Hamilton, ON (Canada). School of Geography and Geology; Jerrett, M.; Beckerman, B.; Arain, M.A. [McMaster Univ., Hamilton, ON (Canada). School of Geography and Geology]|[McMaster Univ., Hamilton, ON (Canada). McMaster Inst. of Environment and Health; Morrison, J. [Carleton Univ., Ottawa, ON (Canada). School of Computer Science; Gilbert, N.L. [Health Canada, Ottawa, ON (Canada). Air Health Effects Div; Brook, J.R. [Meteorological Service of Canada, Toronto, ON (Canada)

2004-10-01

A study was conducted to assess the relation between traffic-generated air pollution and health reactions ranging from childhood asthma to mortality from lung cancer. In particular, it developed a formal method of optimally locating a dense network of air pollution monitoring stations in order to derive an exposure assessment model based on the data obtained from the monitoring stations and related land use, population and biophysical information. The method for determining the locations of 100 nitrogen dioxide monitors in Toronto, Ontario focused on land use, transportation infrastructure and the distribution of at-risk populations. The exposure assessment produced reasonable estimates at the intra-urban scale. This method for locating air pollution monitors effectively maximizes sampling coverage in relation to important socio-demographic characteristics and likely pollution variability. The location-allocation approach integrates many variables into the demand surface to reconfigure a monitoring network and is especially useful for measuring traffic pollutants with fine-scale spatial variability. The method also shows great promise for improving the assessment of exposure to ambient air pollution in epidemiologic studies. 19 refs., 3 tabs., 4 figs.

Dynamics of a recovering Arctic bird population: the importance of climate, density dependence, and site quality

Science.gov (United States)

Bruggeman, Jason E.; Swem, Ted; Andersen, David E.; Kennedy, Patricia L.; Nigro, Debora A.

2015-01-01

Intrinsic and extrinsic factors affect vital rates and population-level processes, and understanding these factors is paramount to devising successful management plans for wildlife species. For example, birds time migration in response, in part, to local and broadscale climate fluctuations to initiate breeding upon arrival to nesting territories, and prolonged inclement weather early in the breeding season can inhibit egg-laying and reduce productivity. Also, density-dependent regulation occurs in raptor populations, as territory size is related to resource availability. Arctic Peregrine Falcons (Falco peregrinus tundrius; hereafter Arctic peregrine) have a limited and northern breeding distribution, including the Colville River Special Area (CRSA) in the National Petroleum Reserve–Alaska, USA. We quantified influences of climate, topography, nest productivity, prey habitat, density dependence, and interspecific competition affecting Arctic peregrines in the CRSA by applying the Dail-Madsen model to estimate abundance and vital rates of adults on nesting cliffs from 1981 through 2002. Arctic peregrine abundance increased throughout the 1980s, which spanned the population's recovery from DDT-induced reproductive failure, until exhibiting a stationary trend in the 1990s. Apparent survival rate (i.e., emigration; death) was negatively correlated with the number of adult Arctic peregrines on the cliff the previous year, suggesting effects of density-dependent population regulation. Apparent survival and arrival rates (i.e., immigration; recruitment) were higher during years with earlier snowmelt and milder winters, and apparent survival was positively correlated with nesting season maximum daily temperature. Arrival rate was positively correlated with average Arctic peregrine productivity along a cliff segment from the previous year and initial abundance was positively correlated with cliff height. Higher cliffs with documented higher productivity (presumably

Estimating large carnivore populations at global scale based on spatial predictions of density and distribution – Application to the jaguar (Panthera onca)

Science.gov (United States)

Robinson, Hugh S.; Abarca, Maria; Zeller, Katherine A.; Velasquez, Grisel; Paemelaere, Evi A. D.; Goldberg, Joshua F.; Payan, Esteban; Hoogesteijn, Rafael; Boede, Ernesto O.; Schmidt, Krzysztof; Lampo, Margarita; Viloria, Ángel L.; Carreño, Rafael; Robinson, Nathaniel; Lukacs, Paul M.; Nowak, J. Joshua; Salom-Pérez, Roberto; Castañeda, Franklin; Boron, Valeria; Quigley, Howard

2018-01-01

Broad scale population estimates of declining species are desired for conservation efforts. However, for many secretive species including large carnivores, such estimates are often difficult. Based on published density estimates obtained through camera trapping, presence/absence data, and globally available predictive variables derived from satellite imagery, we modelled density and occurrence of a large carnivore, the jaguar, across the species’ entire range. We then combined these models in a hierarchical framework to estimate the total population. Our models indicate that potential jaguar density is best predicted by measures of primary productivity, with the highest densities in the most productive tropical habitats and a clear declining gradient with distance from the equator. Jaguar distribution, in contrast, is determined by the combined effects of human impacts and environmental factors: probability of jaguar occurrence increased with forest cover, mean temperature, and annual precipitation and declined with increases in human foot print index and human density. Probability of occurrence was also significantly higher for protected areas than outside of them. We estimated the world’s jaguar population at 173,000 (95% CI: 138,000–208,000) individuals, mostly concentrated in the Amazon Basin; elsewhere, populations tend to be small and fragmented. The high number of jaguars results from the large total area still occupied (almost 9 million km2) and low human densities (conservation actions. PMID:29579129

Neutron area monitoring at storage bunkers of density/moisture gauges

Energy Technology Data Exchange (ETDEWEB)

Garcia-Fuste, M.J. [Grup de Fisica de les Radiacions. Universitat Autonoma de Barcelona (UAB), Edifici Cc, E-08193 Bellaterra (Spain); Amgarou, K., E-mail: khalil.amgarou@uab.ca [Grup de Fisica de les Radiacions. Universitat Autonoma de Barcelona (UAB), Edifici Cc, E-08193 Bellaterra (Spain); Garcia-Orellana, J.; Domingo, C. [Grup de Fisica de les Radiacions. Universitat Autonoma de Barcelona (UAB), Edifici Cc, E-08193 Bellaterra (Spain)

2010-12-15

Previous studies remarked the need of performing neutron personal dosimetry, together with gamma dosimetry, when using portable density/moisture gauges that are normally equipped with gamma and neutron sources. The convenience of our Poly-Allyl-Diglycol-Carbonate (PADC) based neutron dosimeter to perform long-term routine survey of all workers involved in the transport, maintenance and usage of these gauges was also corroborated in the past. This complete dosimetric control offers the possibility to quantify simultaneously individual neutron and gamma doses of workers operating such devices, especially in the most frequent cleaning and maintenance (shutter lubrication) operations of the gauges or in emergency situations that may lead to radiological risk of the persons involved. Another aspect to be considered, from the radioprotection point of view, is the optimization of the occupational and public exposure in the storage bunkers of the gauges. In this work, three storage bunkers, located at three different factories of the PAYMA Cotas S.A.U company, have been monitored for three months using several units of our PADC based neutron dosimeter. Special care has been taken to study also offices near the bunkers with high occupancy rates and passage zones, such as toilets and access areas. Results for all monitored points inside and around the three storage bunkers are presented. Neutron doses inside the bunkers could be relatively high depending on the specific conditions (geometry configuration, localization and shielding composition) of the considered bunker and the number of portable gauges stored.

Neutron area monitoring at storage bunkers of density/moisture gauges

International Nuclear Information System (INIS)

Garcia-Fuste, M.J.; Amgarou, K.; Garcia-Orellana, J.; Domingo, C.

2010-01-01

Previous studies remarked the need of performing neutron personal dosimetry, together with gamma dosimetry, when using portable density/moisture gauges that are normally equipped with gamma and neutron sources. The convenience of our Poly-Allyl-Diglycol-Carbonate (PADC) based neutron dosimeter to perform long-term routine survey of all workers involved in the transport, maintenance and usage of these gauges was also corroborated in the past. This complete dosimetric control offers the possibility to quantify simultaneously individual neutron and gamma doses of workers operating such devices, especially in the most frequent cleaning and maintenance (shutter lubrication) operations of the gauges or in emergency situations that may lead to radiological risk of the persons involved. Another aspect to be considered, from the radioprotection point of view, is the optimization of the occupational and public exposure in the storage bunkers of the gauges. In this work, three storage bunkers, located at three different factories of the PAYMA Cotas S.A.U company, have been monitored for three months using several units of our PADC based neutron dosimeter. Special care has been taken to study also offices near the bunkers with high occupancy rates and passage zones, such as toilets and access areas. Results for all monitored points inside and around the three storage bunkers are presented. Neutron doses inside the bunkers could be relatively high depending on the specific conditions (geometry configuration, localization and shielding composition) of the considered bunker and the number of portable gauges stored.

Monitoring requirements for detecting tidal barrage induced changes to estuary bird populations

International Nuclear Information System (INIS)

Davenport, T.; Jeffers, J.N.R.; North, P.M.; Clark, N.A.; Langston, R.H.W.; Prys-Jones, R.P.

1990-01-01

This study was performed to examine the monitoring requirements for detecting tidal barrage induced changes to estuary bird populations, focussing mainly on the Mersey estuary. The degree of variability in populations between years for a number of species within the Mersey, Dee, Alt and Ribble were ascertained. The number of counts needed each winter, before and after barrage construction, were assessed. The percentage charge detectable for species was predicted. One east coast estuary (the Wash) was investigated for comparison of the effects of influences of severe weather. (UK)

Harmful Algae Bloom Occurrence in Urban Ponds: Relationship of Toxin Levels with Cell Density and Species Composition

Science.gov (United States)

Retention ponds constructed within urban watershed areas of high density populations are common as a result of green infrastructure applications. Several urban ponds in the Northern Kentucky area were monitored for algal community (algae and cyanobacteria) from October 2012 to Se...

Regulation of Population Densities of Heterodera cajani and Other Plant-Parasitic Nematodes by Crop Rotations on Vertisols, in Semi-Arid Tropical Production Systems in India

Science.gov (United States)

Sharma, S. B.; Rego, T. J.; Mohiuddin, M.; Rao, V. N.

1996-01-01

The significance of double crop (intercrop and sequential crop), single crop (rainy season crop fallow from June to September), and rotations on densities of Heterodera cajani, Helicotylenchus retusus, and Rotylenchulus reniformis was studied on Vertisol (Typic Pellusterts) between 1987 and 1993. Cowpea (Vigna sinensis), mungbean (Phaseolus aureus), and pigeonpea (Cajanus cajan) greatly increased the population densities of H. cajani and suppressed the population densities of other plant-parasitic nematodes. Mean population densities of H. cajani were about 8 times lower in single crop systems than in double crop systems, with pigeonpea as a component intercrop. Plots planted to sorghum, safflower, and chickpea in the preceding year contained fewer H. cajani eggs and juveniles than did plots previously planted to pigeonpea, cowpea, or mungbean. Continuous cropping of sorghum in the rainy season and safflower in the post-rainy season markedly reduced the population density of H. cajani. Sorghum, safflower, and chickpea favored increased population densities of H. retusus. Adding cowpea to the system resulted in a significant increase in the densities of R. reniformis. Mean densities of total plant-parasitic nematodes were three times greater in double crop systems, with pigeonpea as a component intercrop than in single crop systems with rainy season fallow component. Cropping systems had a regulatory effect on the nematode populations and could be an effective nematode management tactic. Intercropping of sorghum with H. cajani tolerant pigeonpea could be effective in increasing the productivity of traditional production systems in H. cajani infested regions. PMID:19277141

Maternal effects on male weaponry: female dung beetles produce major sons with longer horns when they perceive higher population density

Directory of Open Access Journals (Sweden)

Buzatto Bruno A

2012-07-01

Full Text Available Abstract Background Maternal effects are environmental influences on the phenotype of one individual that are due to the expression of genes in its mother, and are expected to evolve whenever females are better capable of assessing the environmental conditions that their offspring will experience than the offspring themselves. In the dung beetle Onthophagus taurus, conditional male dimorphism is associated with alternative reproductive tactics: majors fight and guard females whereas minors sneak copulations. Furthermore, variation in dung beetle population density has different fitness consequences for each male morph, and theory predicts that higher population density might select for a higher frequency of minors and/or greater expenditure on weaponry in majors. Because adult dung beetles provide offspring with all the nutritional resources for their development, maternal effects strongly influence male phenotype. Results Here we tested whether female O. taurus are capable of perceiving population density, and responding by changing the phenotype of their offspring. We found that mothers who were reared with other conspecifics in their pre-mating period produced major offspring that had longer horns across a wider range of body sizes than the major offspring of females that were reared in isolation in their pre-mating period. Moreover, our results indicate that this maternal effect on male weaponry does not operate through the amount of dung provided by females to their offspring, but is rather transmitted through egg or brood mass composition. Finally, although theory predicts that females experiencing higher density might produce more minor males, we found no support for this, rather the best fitting models were equivocal as to whether fewer or the same proportions of minors were produced. Conclusions Our study describes a new type of maternal effect in dung beetles, which probably allows females to respond to population density adaptively

Population demography of the muskoxen in Jameson Land, 1982-1990

Directory of Open Access Journals (Sweden)

Peter Aastrup

2000-03-01

Full Text Available Studies of the Jameson Land muskox population in Northeast Greenland were conducted 1982-1990 in conjunction with an oil exploration. A population monitoring program consisted of one yearly aerial survey in late winter and a ground survey for population composition in August. The estimated unadjusted minimum average population size was approximately 4000 with a maximum size of 4700 and a minimum of 2800 muskoxen. The monitoring program was adequate to detect an annual change of about 10%. Population composition data proved to be essential. The only indication of a negative impact from oil exploration was detected in the fraction of yearlings. The average calf proportion was roughly 18% and about half of the calves died during their first year. The population density and composition was similar to the Banks Island muskox population in Canada and to the West Greenland population although the latter population had a higher productivity. Seismic operations and/or climatic conditions may have had a negative impact on the calf survival during 1986-1989, when fractions of yearlings were significantly lower than before and after the exploration.

Effects of Tropical Rotation Crops on Meloidogyne arenaria Population Densities and Vegetable Yields in Microplots.

Science.gov (United States)

McSorley, R; Dickson, D W; de Brito, J A; Hewlett, T E; Frederick, J J

1994-06-01

The effects of 12 summer crop rotation treatments on population densities of Meloidogyne arenaria race 1 and on yields of subsequent spring vegetable crops were determined in microplots. The crop sequence was: (i) rotation crops during summer 1991 ; (ii) cover crop of rye (Secale cereale) during winter 1991-92; (iii) squash (Cucurbita pepo) during spring 1992; (iv) rotation crops during summer 1992; (v) rye during winter 1992-93; (vi) eggplant (Solanum melongena) during spring 1993. The 12 rotation treatments were castor (Ricinus communis), cotton (Gossypium hirsutum), velvetbean (Mucuna deeringiana), crotalaria (Crotalaria spectabilis), fallow, hairy indigo (Indigofera hirsuta), American jointvetch (Aeschynomene americana), sorghum-sudangrass (Sorghum bicolor x S. sudanense), soybean (Glycine max), horsebean (Canavalia ensiformis), sesame (Sesamum indicum), and peanut (Arachis hypogaea). Compared to peanut, the first eight rotation treatments resulted in lower (P crops may provide a means for depressing M. arenaria population densities on a short-term basis to enhance yields in a subsequent susceptible vegetable crop.

Density and spin linear response of atomic Fermi superfluids with population imbalance in the BCS–BEC crossover

International Nuclear Information System (INIS)

Guo, Hao; Li, Yang; He, Yan; Chien, Chih-Chun

2014-01-01

We present a theoretical study of the density and spin (representing the two components) linear response of Fermi superfluids with tunable attractive interactions and population imbalance. In both linear response theories, we find that the fluctuations of the order parameter must be treated on equal footing with the gauge transformations associated with the symmetries of the Hamiltonian so that important constraints including various sum rules can be satisfied. Both theories can be applied to the whole BCS–Bose–Einstein condensation crossover. The spin linear responses are qualitatively different with and without population imbalance because collective-mode effects from the fluctuations of the order parameter survive in the presence of population imbalance, even though the associated symmetry is not broken by the order parameter. Since a polarized superfluid becomes unstable at low temperatures in the weak and intermediate coupling regimes, we found that the density and spin susceptibilities diverge as the system approaches the unstable regime, but the emergence of phase separation preempts the divergence. (paper)

Influence of power density on the setting behaviour of light-cured glass-ionomer cements monitored by ultrasound measurements.

Science.gov (United States)

Tonegawa, Motoka; Yasuda, Genta; Chikako, Takubo; Tamura, Yukie; Yoshida, Takeshi; Kurokawa, Hiroyasu; Miyazaki, Masashi

2009-07-01

To monitor the influence of the power density of the curing unit on the setting behaviour of light-cured glass-ionomer cements (LCGICs) using ultrasound measurements. The ultrasound equipment comprised a pulser-receiver, transducers and an oscilloscope. The LCGICs used were Fuji II LC, Fuji II LC EM and Fuji Filling LC. The cements were mixed according to the manufacturer's instructions and then inserted into a transparent mould. The specimens were placed on the sample stage and cured with power densities of 0 (no irradiation), 200 or 600 mW/cm(2). The transit time through the cement disk was divided by the specimen thickness and then the longitudinal ultrasound velocity (V) within the material was obtained. Analysis of variance and Tukey's Honestly Significantly Different test were used to compare the V values between the set cements. When the LCGICs were light-irradiated, each curve displayed an initial plateau at approximately 1500 m/s and then rapidly increased to a second plateau at approximately 2600 m/s. The rate of increase of V was retarded when the cements were light-irradiated with a power density of 200 mW/cm(2) than with a power density of 600 mW/cm(2). Although sonic echoes were detected from the beginning of the measurements, the rates of increase of the sonic velocity were relatively slow when the cement was not light-irradiated. The ultrasound device monitored the setting processes of LCGICs accurately based on the longitudinal V. The polymerization behaviour of LCGICs was shown to be affected by the power density of the curing unit.

Population age and initial density in a patchy environment affect the occurrence of abrupt transitions in a birth-and-death model of Taylor's law

Science.gov (United States)

Jiang, Jiang; DeAngelis, Donald L.; Zhang, B.; Cohen, J.E.

2014-01-01

Taylor's power law describes an empirical relationship between the mean and variance of population densities in field data, in which the variance varies as a power, b, of the mean. Most studies report values of b varying between 1 and 2. However, Cohen (2014a) showed recently that smooth changes in environmental conditions in a model can lead to an abrupt, infinite change in b. To understand what factors can influence the occurrence of an abrupt change in b, we used both mathematical analysis and Monte Carlo samples from a model in which populations of the same species settled on patches, and each population followed independently a stochastic linear birth-and-death process. We investigated how the power relationship responds to a smooth change of population growth rate, under different sampling strategies, initial population density, and population age. We showed analytically that, if the initial populations differ only in density, and samples are taken from all patches after the same time period following a major invasion event, Taylor's law holds with exponent b=1, regardless of the population growth rate. If samples are taken at different times from patches that have the same initial population densities, we calculate an abrupt shift of b, as predicted by Cohen (2014a). The loss of linearity between log variance and log mean is a leading indicator of the abrupt shift. If both initial population densities and population ages vary among patches, estimates of b lie between 1 and 2, as in most empirical studies. But the value of b declines to ~1 as the system approaches a critical point. Our results can inform empirical studies that might be designed to demonstrate an abrupt shift in Taylor's law.

Estimation of the adult male population of sweet potato weevil, Cylas formicarius (Fabricius) at its low-density period on Kikai Island in Japan

International Nuclear Information System (INIS)

Yamaguchi, T.; Hatono, T.; Izumi, S.; Nishihara, S.; Kimura, K.; Torigoe, H.; Tanaka, T.; Miyaji, K.; Hara, Y.; Ueda, A.; Shigei, F.

2008-01-01

The sweet potato weevil, Cylas formicarius (Fabricius) is a major insect pest of the sweet potato, Ipomoea batatas (L.) Lam. throughout the tropical and subtropical regions of the world. We estimated the entire adult male population of C. formicarius at its low-density period on Kikai Island, Kagoshima Pref., Japan. The population of adult males at the high-density period in September was about 5 times larger than that at its low-density period in May, both of which were estimated by Yamamura's method. Using this calculation in combination with an estimate of the maximal population size (4 x 10E6) by Sugimoto et al. in 1994, the total number of male weevils at their low-density period can be assumed to be less than 8 x 10E5

Hierarchical population monitoring of greater sage-grouse (Centrocercus urophasianus) in Nevada and California—Identifying populations for management at the appropriate spatial scale

Science.gov (United States)

Coates, Peter S.; Prochazka, Brian G.; Ricca, Mark A.; Wann, Gregory T.; Aldridge, Cameron L.; Hanser, Steven E.; Doherty, Kevin E.; O'Donnell, Michael S.; Edmunds, David R.; Espinosa, Shawn P.

2017-08-10

Population ecologists have long recognized the importance of ecological scale in understanding processes that guide observed demographic patterns for wildlife species. However, directly incorporating spatial and temporal scale into monitoring strategies that detect whether trajectories are driven by local or regional factors is challenging and rarely implemented. Identifying the appropriate scale is critical to the development of management actions that can attenuate or reverse population declines. We describe a novel example of a monitoring framework for estimating annual rates of population change for greater sage-grouse (Centrocercus urophasianus) within a hierarchical and spatially nested structure. Specifically, we conducted Bayesian analyses on a 17-year dataset (2000–2016) of lek counts in Nevada and northeastern California to estimate annual rates of population change, and compared trends across nested spatial scales. We identified leks and larger scale populations in immediate need of management, based on the occurrence of two criteria: (1) crossing of a destabilizing threshold designed to identify significant rates of population decline at a particular nested scale; and (2) crossing of decoupling thresholds designed to identify rates of population decline at smaller scales that decouple from rates of population change at a larger spatial scale. This approach establishes how declines affected by local disturbances can be separated from those operating at larger scales (for example, broad-scale wildfire and region-wide drought). Given the threshold output from our analysis, this adaptive management framework can be implemented readily and annually to facilitate responsive and effective actions for sage-grouse populations in the Great Basin. The rules of the framework can also be modified to identify populations responding positively to management action or demonstrating strong resilience to disturbance. Similar hierarchical approaches might be beneficial

Extrapolating cetacean densities to quantitatively assess human impacts on populations in the high seas.

Science.gov (United States)

Mannocci, Laura; Roberts, Jason J; Miller, David L; Halpin, Patrick N

2017-06-01

As human activities expand beyond national jurisdictions to the high seas, there is an increasing need to consider anthropogenic impacts to species inhabiting these waters. The current scarcity of scientific observations of cetaceans in the high seas impedes the assessment of population-level impacts of these activities. We developed plausible density estimates to facilitate a quantitative assessment of anthropogenic impacts on cetacean populations in these waters. Our study region extended from a well-surveyed region within the U.S. Exclusive Economic Zone into a large region of the western North Atlantic sparsely surveyed for cetaceans. We modeled densities of 15 cetacean taxa with available line transect survey data and habitat covariates and extrapolated predictions to sparsely surveyed regions. We formulated models to reduce the extent of extrapolation beyond covariate ranges, and constrained them to model simple and generalizable relationships. To evaluate confidence in the predictions, we mapped where predictions were made outside sampled covariate ranges, examined alternate models, and compared predicted densities with maps of sightings from sources that could not be integrated into our models. Confidence levels in model results depended on the taxon and geographic area and highlighted the need for additional surveying in environmentally distinct areas. With application of necessary caution, our density estimates can inform management needs in the high seas, such as the quantification of potential cetacean interactions with military training exercises, shipping, fisheries, and deep-sea mining and be used to delineate areas of special biological significance in international waters. Our approach is generally applicable to other marine taxa and geographic regions for which management will be implemented but data are sparse. © 2016 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

Comparison of Three Plot Selection Methods for Estimating Change in Temporally Variable, Spatially Clustered Populations.

Energy Technology Data Exchange (ETDEWEB)

Thompson, William L. [Bonneville Power Administration, Portland, OR (US). Environment, Fish and Wildlife

2001-07-01

Monitoring population numbers is important for assessing trends and meeting various legislative mandates. However, sampling across time introduces a temporal aspect to survey design in addition to the spatial one. For instance, a sample that is initially representative may lose this attribute if there is a shift in numbers and/or spatial distribution in the underlying population that is not reflected in later sampled plots. Plot selection methods that account for this temporal variability will produce the best trend estimates. Consequently, I used simulation to compare bias and relative precision of estimates of population change among stratified and unstratified sampling designs based on permanent, temporary, and partial replacement plots under varying levels of spatial clustering, density, and temporal shifting of populations. Permanent plots produced more precise estimates of change than temporary plots across all factors. Further, permanent plots performed better than partial replacement plots except for high density (5 and 10 individuals per plot) and 25% - 50% shifts in the population. Stratified designs always produced less precise estimates of population change for all three plot selection methods, and often produced biased change estimates and greatly inflated variance estimates under sampling with partial replacement. Hence, stratification that remains fixed across time should be avoided when monitoring populations that are likely to exhibit large changes in numbers and/or spatial distribution during the study period. Key words: bias; change estimation; monitoring; permanent plots; relative precision; sampling with partial replacement; temporary plots.

Annual dynamics of wild bee densities: attractiveness and productivity effects of oilseed rape.

Science.gov (United States)

Riedinger, Verena; Mitesser, Oliver; Hovestadt, Thomas; Steffan-Dewenter, Ingolf; Holzschuh, Andrea

2015-05-01

Mass-flowering crops may affect long-term population dynamics, but effects on pollinators have never been studied across several years. We monitored wild bees in oilseed rape fields in 16 landscapes in Germany in two consecutive years. Effects on bee densities of landscape oilseed rape cover in the years of monitoring and in the previous years were evaluated with landscape data from three consecutive years. We fit empirical data to a mechanistic model to provide estimates for oilseed rape attractiveness and its effect on bee productivity in comparison to the rest of the landscape, and we evaluated consequences for pollinator densities in consecutive years. Our results show that high oilseed rape cover in the previous year enhances current densities of wild bees (except for bumble bees). Moreover, we show a strong attractiveness of and dilution on (i.e., decreasing bee densities with increasing landscape oilseed rape cover) oilseed rape for bees during flowering in the current year, modifying the effect of the previous year's oilseed rape cover in the case of wild bees (excluding Bombus). As long as other factors such as nesting sites or natural enemies do not limit bee reproduction, our findings suggest long-term positive effects of mass-flowering crops on bee populations, at least for non-Bombus generalists, which possibly help to maintain crop pollination services even when crop area increases. Similar effects are conceivable for other organisms providing ecosystem services in annual crops and should be considered in future studies.

Fetal size monitoring and birth-weight prediction: a new population-based approach.

Science.gov (United States)

Gjessing, H K; Grøttum, P; Økland, I; Eik-Nes, S H

2017-04-01

To develop a complete, population-based system for ultrasound-based fetal size monitoring and birth-weight prediction for use in the second and third trimesters of pregnancy. Using 31 516 ultrasound examinations from a population-based Norwegian clinical database, we constructed fetal size charts for biparietal diameter, femur length and abdominal circumference from 24 to 42 weeks' gestation. A reference curve of median birth weight for gestational age was estimated using 45 037 birth weights. We determined how individual deviations from the expected ultrasound measures predicted individual percentage deviations from expected birth weight. The predictive quality was assessed by explained variance of birth weight and receiver-operating characteristics curves for prediction of small-for-gestational age. A curve for intrauterine estimated fetal weight was constructed. Charts were smoothed using the gamlss non-linear regression method. The population-based approach, using bias-free ultrasound gestational age, produces stable estimates of size-for-age and weight-for-age curves in the range 24-42 weeks' gestation. There is a close correspondence between percentage deviations and percentiles of birth weight by gestational age, making it easy to convert between the two. The variance of birth weight that can be 'explained' by ultrasound increases from 8% at 20 weeks up to 67% around term. Intrauterine estimated fetal weight is 0-106 g higher than median birth weight in the preterm period. The new population-based birth-weight prediction model provides a simple summary measure, the 'percentage birth-weight deviation', to be used for fetal size monitoring throughout the third trimester. Predictive quality of the model can be measured directly from the population data. The model computes both median observed birth weight and intrauterine estimated fetal weight. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Copyright © 2016 ISUOG. Published by John

Associations of all-cause mortality with census-based neighbourhood deprivation and population density in Japan: a multilevel survival analysis.

Directory of Open Access Journals (Sweden)

Tomoki Nakaya

Full Text Available BACKGROUND: Despite evidence that neighbourhood conditions affect residents' health, no prospective studies of the association between neighbourhood socio-demographic factors and all-cause mortality have been conducted in non-Western societies. Thus, we examined the effects of areal deprivation and population density on all-cause mortality in Japan. METHODS: We employed census and survival data from the Japan Public Health Center-based Prospective Study, Cohort I (n = 37,455, consisting of middle-aged residents (40 to 59 years at the baseline in 1990 living in four public health centre districts. Data spanned between 1990 and 2010. A multilevel parametric proportional-hazard regression model was applied to estimate the hazard ratios (HRs of all-cause mortality by two census-based areal variables--areal deprivation index and population density--as well as individualistic variables such as socioeconomic status and various risk factors. RESULTS: We found that areal deprivation and population density had moderate associations with all-cause mortality at the neighbourhood level based on the survival data with 21 years of follow-ups. Even when controlling for individualistic socio-economic status and behavioural factors, the HRs of the two areal factors (using quartile categorical variables significantly predicted mortality. Further, this analysis indicated an interaction effect of the two factors: areal deprivation prominently affects the health of residents in neighbourhoods with high population density. CONCLUSIONS: We confirmed that neighbourhood socio-demographic factors are significant predictors of all-cause death in Japanese non-metropolitan settings. Although further study is needed to clarify the cause-effect relationship of this association, the present findings suggest that health promotion policies should consider health disparities between neighbourhoods and possibly direct interventions towards reducing mortality in densely

Lying in wait: Limiting factors on a low-density ungulate population and the latent traits that can facilitate escape from them

Science.gov (United States)

Joly, Kyle; Craig, Tim; Cameron, Matthew D.; Gall, Adrian E.; Sorum, Mathew S.

2017-11-01

Predation, habitat, hunting, and environmental conditions have all been implicated as regulatory mechanisms in ungulate populations. The low-density equilibrium hypothesis predicts that in low-density populations, predators regulate their prey and that the population will not escape unless predation pressure is eased. We evaluated survival of adult and juvenile moose (Alces alces) in north-central Alaska to determine whether or not the population supported the hypothesis. We instrumented adult male and female moose with radiocollars and used aerial observations to track parturition and subsequent survival of juvenile moose. Generalized linear mixed-effects models were used to assess survival. Adult annual survival rates were high (∼89%), but may be negatively influenced by winter conditions. Migratory status did not affect moose survivorship or productivity. Approximately 60% of the calf crop died before 5 months of age. Productivity was significantly lower in the northern section of the study area where there is less high-quality habitat, suggesting that, even in this low-density population, nutrition could be a limiting factor. It appears that predation on young calves, winter weather, and nutritional constraints may be interacting to limit this population. Latent traits, such as overproduction of calves and migratory behavior, which do not currently enhance fitness, may persist within this population so that individuals with these traits can reap benefits when environmental conditions change.

NODC Standard Format Herring Survey Population Density and Distribution (F057) Data (1976-1977) (NODC Accession 0014189)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data type contains data from aircraft surveys of herring schools. These data were collected to provide information on herring population density and...

Genetic monitoring of experimental Drosophila populations exposed to X-radiation and treated with melanin

International Nuclear Information System (INIS)

Mosseh, I.B.; Savchenko, V.K.; Lyakh, I.P.

1985-01-01

Monitoring of laboratory populations of Drosophila over four years has demonstrated that X radiation of 0.25 C/kg, delivered during the life span of each generation, causes a decrease of 20% and 30%, on the average, in the number of individuals in 1-55 generations and 45-55 generations, respectively. The antimutagen, melanin, added to a nutrient medium has no effect on the number of individuals in populations

Oncorhynchus nerka population monitoring in the Sawtooth Valley Lakes

International Nuclear Information System (INIS)

Teuscher, D.M.; Taki, D.; Ariwite, K.

1996-01-01

Critical habitat for endangered Snake River sockeye salmon includes five rearing lakes located in the Sawtooth Valley of central Idaho. Most of the lakes contain either introduced or endemic kokanee populations. Snake River sockeye occur naturally in Redfish Lake, and are being stocked in Redfish and Pettit Lakes. Because kokanee compete with sockeye for limited food resources, understanding population characteristics of both species such as spawn timing, egg-to-fry survival, distribution and abundance are important components of sockeye recovery. This chapter describes some of those characteristics. In 1995, hydroacoustic estimates of O. nerka densities in the Sawtooth Valley Lakes ranged from 57 to 465 fish/ha. Densities were greatest in Pettit followed by Redfish (167), Alturas (95), and Stanley Lakes. O. nerka numbers increased from 1994 values in Pettit and Alturas Lakes, but declined in Redfish and Stanley. Despite a decline in total lake abundance, O. nerka biomass estimates in Redfish Lake increased. Approximately 144,000 kokanee fry recruited to Redfish Lake from Fishhook Creek. O. nerka fry recruitment to Stanley and Alturas lake was 5,000 and 30,000 fry, respectively. Egg-to-fry survival was 14% in Fishhook and 7% in Stanley Lake Creek. In Fishhook Creek, kokanee spawning escapement was estimated using stream surveys and a weir. Escapement estimates were 4,860 from weir counts, and 7,000 from stream surveys. As part of the kokanee reduction program, 385 of the spawning female kokanee were culled. Escapement for Stanley Lake Creek was only 60 fish, a ten fold decrease from 1994. In Alturas Lake, kokanee spawners dropped by 50% to 1,600

Oncorhynchus nerka population monitoring in the Sawtooth Valley Lakes

Energy Technology Data Exchange (ETDEWEB)

Teuscher, D.M.; Taki, D.; Ariwite, K.

1996-05-01

Critical habitat for endangered Snake River sockeye salmon includes five rearing lakes located in the Sawtooth Valley of central Idaho. Most of the lakes contain either introduced or endemic kokanee populations. Snake River sockeye occur naturally in Redfish Lake, and are being stocked in Redfish and Pettit Lakes. Because kokanee compete with sockeye for limited food resources, understanding population characteristics of both species such as spawn timing, egg-to-fry survival, distribution and abundance are important components of sockeye recovery. This chapter describes some of those characteristics. In 1995, hydroacoustic estimates of O. nerka densities in the Sawtooth Valley Lakes ranged from 57 to 465 fish/ha. Densities were greatest in Pettit followed by Redfish (167), Alturas (95), and Stanley Lakes. O. nerka numbers increased from 1994 values in Pettit and Alturas Lakes, but declined in Redfish and Stanley. Despite a decline in total lake abundance, O. nerka biomass estimates in Redfish Lake increased. Approximately 144,000 kokanee fry recruited to Redfish Lake from Fishhook Creek. O. nerka fry recruitment to Stanley and Alturas lake was 5,000 and 30,000 fry, respectively. Egg-to-fry survival was 14% in Fishhook and 7% in Stanley Lake Creek. In Fishhook Creek, kokanee spawning escapement was estimated using stream surveys and a weir. Escapement estimates were 4,860 from weir counts, and 7,000 from stream surveys. As part of the kokanee reduction program, 385 of the spawning female kokanee were culled. Escapement for Stanley Lake Creek was only 60 fish, a ten fold decrease from 1994. In Alturas Lake, kokanee spawners dropped by 50% to 1,600.

Effect of Trait Heritability, Training Population Size and Marker Density on Genomic Prediction Accuracy Estimation in 22 bi-parental Tropical Maize Populations.

Science.gov (United States)

Zhang, Ao; Wang, Hongwu; Beyene, Yoseph; Semagn, Kassa; Liu, Yubo; Cao, Shiliang; Cui, Zhenhai; Ruan, Yanye; Burgueño, Juan; San Vicente, Felix; Olsen, Michael; Prasanna, Boddupalli M; Crossa, José; Yu, Haiqiu; Zhang, Xuecai

2017-01-01

Genomic selection is being used increasingly in plant breeding to accelerate genetic gain per unit time. One of the most important applications of genomic selection in maize breeding is to predict and select the best un-phenotyped lines in bi-parental populations based on genomic estimated breeding values. In the present study, 22 bi-parental tropical maize populations genotyped with low density SNPs were used to evaluate the genomic prediction accuracy ( r MG ) of the six trait-environment combinations under various levels of training population size (TPS) and marker density (MD), and assess the effect of trait heritability ( h 2 ), TPS and MD on r MG estimation. Our results showed that: (1) moderate r MG values were obtained for different trait-environment combinations, when 50% of the total genotypes was used as training population and ~200 SNPs were used for prediction; (2) r MG increased with an increase in h 2 , TPS and MD, both correlation and variance analyses showed that h 2 is the most important factor and MD is the least important factor on r MG estimation for most of the trait-environment combinations; (3) predictions between pairwise half-sib populations showed that the r MG values for all the six trait-environment combinations were centered around zero, 49% predictions had r MG values above zero; (4) the trend observed in r MG differed with the trend observed in r MG / h , and h is the square root of heritability of the predicted trait, it indicated that both r MG and r MG / h values should be presented in GS study to show the accuracy of genomic selection and the relative accuracy of genomic selection compared with phenotypic selection, respectively. This study provides useful information to maize breeders to design genomic selection workflow in their breeding programs.

Effect of Trait Heritability, Training Population Size and Marker Density on Genomic Prediction Accuracy Estimation in 22 bi-parental Tropical Maize Populations

Directory of Open Access Journals (Sweden)

Ao Zhang

2017-11-01

Full Text Available Genomic selection is being used increasingly in plant breeding to accelerate genetic gain per unit time. One of the most important applications of genomic selection in maize breeding is to predict and select the best un-phenotyped lines in bi-parental populations based on genomic estimated breeding values. In the present study, 22 bi-parental tropical maize populations genotyped with low density SNPs were used to evaluate the genomic prediction accuracy (rMG of the six trait-environment combinations under various levels of training population size (TPS and marker density (MD, and assess the effect of trait heritability (h2, TPS and MD on rMG estimation. Our results showed that: (1 moderate rMG values were obtained for different trait-environment combinations, when 50% of the total genotypes was used as training population and ~200 SNPs were used for prediction; (2 rMG increased with an increase in h2, TPS and MD, both correlation and variance analyses showed that h2 is the most important factor and MD is the least important factor on rMG estimation for most of the trait-environment combinations; (3 predictions between pairwise half-sib populations showed that the rMG values for all the six trait-environment combinations were centered around zero, 49% predictions had rMG values above zero; (4 the trend observed in rMG differed with the trend observed in rMG/h, and h is the square root of heritability of the predicted trait, it indicated that both rMG and rMG/h values should be presented in GS study to show the accuracy of genomic selection and the relative accuracy of genomic selection compared with phenotypic selection, respectively. This study provides useful information to maize breeders to design genomic selection workflow in their breeding programs.

Spatio-temporal dynamics of a fish predator: Density-dependent and hydrographic effects on Baltic Sea cod population.

Directory of Open Access Journals (Sweden)

Valerio Bartolino

Full Text Available Understanding the mechanisms of spatial population dynamics is crucial for the successful management of exploited species and ecosystems. However, the underlying mechanisms of spatial distribution are generally complex due to the concurrent forcing of both density-dependent species interactions and density-independent environmental factors. Despite the high economic value and central ecological importance of cod in the Baltic Sea, the drivers of its spatio-temporal population dynamics have not been analytically investigated so far. In this paper, we used an extensive trawl survey dataset in combination with environmental data to investigate the spatial dynamics of the distribution of the Eastern Baltic cod during the past three decades using Generalized Additive Models. The results showed that adult cod distribution was mainly affected by cod population size, and to a minor degree by small-scale hydrological factors and the extent of suitable reproductive areas. As population size decreases, the cod population concentrates to the southern part of the Baltic Sea, where the preferred more marine environment conditions are encountered. Using the fitted models, we predicted the Baltic cod distribution back to the 1970s and a temporal index of cod spatial occupation was developed. Our study will contribute to the management and conservation of this important resource and of the ecosystem where it occurs, by showing the forces shaping its spatial distribution and therefore the potential response of the population to future exploitation and environmental changes.

Demographic monitoring and population viability analysis of two rare beardtongues from the Uinta Basin

Science.gov (United States)

McCaffery, Rebecca M.; Reisor, Rita; Irvine, Kathryn M.; Brunson, Jessi

2014-01-01

Energy development, in combination with other environmental stressors, poses a persistent threat to rare species endemic to the energy-producing regions of the Western United States. Demographic analyses of monitored populations can provide key information on the natural dynamics of threatened plant and animal populations, and how they might be affected by ongoing and future development. In the Uinta Basin in Utah and Colorado, Graham’s beardtongue (Penstemon grahamii) and White River beardtongue (Penstemon scariosus var. albifluvis) are two rare endemic wildflowers that persist on oil shale habitats heavily impacted by current energy exploration and development, and slated for expanded traditional drilling and oil shale development. We described demographic characteristics and population viability for two populations of each species that have been monitored since 2004. First, we measured population size, survival rates, transitions between life stages, and recruitment using individually marked plants at the four study areas. Then, we used matrix population models to determine stochastic population growth rates (λ) and the probability that each population would persist 50 years into the future, given current conditions. The two P. grahamii study plots had small populations averaging 70 adult plants, and relatively constant and high survival in both vegetative and flowering plants. The two P. scariosus var. albifluvis study plots had populations that averaged 120 adult plants, with high and stable survival in flowering plants and variable survival in vegetative plants. Recruitment of new seedlings into all populations was low and variable, with most recruitment occurring in one or two years. Both P. grahamii populations had λ near 1.0 (stable). One P. scariosus var. albifluvis population appeared to be declining (λ=0.97), while the other was increasing (λ=1.16). Our analyses reveal populations that appear relatively stable, but that are

Detectability counts when assessing populations for biodiversity targets.

Directory of Open Access Journals (Sweden)

Silviu O Petrovan

Full Text Available Efficient, practical and accurate estimates of population parameters are a necessary basis for effective conservation action to meet biodiversity targets. The brown hare is representative of many European farmland species: historically widespread and abundant but having undergone rapid declines as a result of agricultural intensification. As a priority species in the UK Biodiversity Action Plan, it has national targets for population increase that are part of wider national environmental indicators. Previous research has indicated that brown hare declines have been greatest in pastural landscapes and that gains might be made by focussing conservation effort there. We therefore used hares in pastural landscapes to examine how basic changes in survey methodology can affect the precision of population density estimates and related these to national targets for biodiversity conservation in the UK. Line transects for hares carried out at night resulted in higher numbers of detections, had better-fitting detection functions and provided more robust density estimates with lower effort than those during the day, due primarily to the increased probability of detection of hares at night and the nature of hare responses to the observer. Hare spring densities varied widely within a single region, with a pooled mean of 20.6 hares km(-2, significantly higher than the reported national average of hares in pastures of 3.3 hares km(-2. The high number of encounters allowed us to resolve hare densities at site, season and year scales. We demonstrate how survey conduct can impact on data quantity and quality with implications for setting and monitoring biodiversity targets. Our case study of the brown hare provides evidence that for wildlife species with low detectability, large scale volunteer-based monitoring programmes, either species specific or generalist, might be more successfully and efficiently carried out by a small number of trained personnel able to

A principled dimension-reduction method for the population density approach to modeling networks of neurons with synaptic dynamics.

Science.gov (United States)

Ly, Cheng

2013-10-01

The population density approach to neural network modeling has been utilized in a variety of contexts. The idea is to group many similar noisy neurons into populations and track the probability density function for each population that encompasses the proportion of neurons with a particular state rather than simulating individual neurons (i.e., Monte Carlo). It is commonly used for both analytic insight and as a time-saving computational tool. The main shortcoming of this method is that when realistic attributes are incorporated in the underlying neuron model, the dimension of the probability density function increases, leading to intractable equations or, at best, computationally intensive simulations. Thus, developing principled dimension-reduction methods is essential for the robustness of these powerful methods. As a more pragmatic tool, it would be of great value for the larger theoretical neuroscience community. For exposition of this method, we consider a single uncoupled population of leaky integrate-and-fire neurons receiving external excitatory synaptic input only. We present a dimension-reduction method that reduces a two-dimensional partial differential-integral equation to a computationally efficient one-dimensional system and gives qualitatively accurate results in both the steady-state and nonequilibrium regimes. The method, termed modified mean-field method, is based entirely on the governing equations and not on any auxiliary variables or parameters, and it does not require fine-tuning. The principles of the modified mean-field method have potential applicability to more realistic (i.e., higher-dimensional) neural networks.

Toward youth self-report of health and quality of life in population monitoring.

Science.gov (United States)

Topolski, Tari D; Edwards, Todd C; Patrick, Donald L

2004-01-01

This paper addresses population monitoring of youth health and quality of life, including the concepts used, methodological and practical criteria for indicators, and existing surveys and measures. Current population surveys of youth generally focus on poor health, such as disability or health-risk behaviors. Although these are important end points, indicators of illness or risk do not reflect the health or life perspective of the majority of youth who do not experience health problems. The measures used to monitor youth health should be appropriate and sensitive to future needs and capture the perspectives of youths. Two potential concepts for this "scorecard" are self-perceived health and quality of life, which have been shown to be useful in adults. For youth, the quality of life framework seems particularly relevant as it incorporates both positive and negative aspects of health and well-being and also captures salient aspects of health other than physical health, such as sense of self, social relationships, environment and culture, and life satisfaction.

Use of black light traps to monitor the abundance, spread, and flight behavior of Halyomorpha halys (Hemiptera: Pentatomidae).

Science.gov (United States)

Nielsen, Anne L; Holmstrom, Kristian; Hamilton, George C; Cambridge, John; Ingerson-Mahar, Joseph

2013-06-01

Monitoring the distribution and abundance of an invasive species is challenging, especially during the initial years of spread when population densities are low and basic biology and monitoring methods are being investigated. Brown marmorated stink bug (Halyomorpha halys (Stål)) is an invasive agricultural and urban pest that was first detected in the United States in the late 1990s. At the time of its detection, no method was available to effectively track H. halys populations, which are highly mobile and polyphagous. One possible solution was the utilization of black light traps, which are nonspecific traps attractive to night flying insects. To determine if black light traps are a reliable monitoring tool for H. halys, a state-wide network of 40-75 traps located on New Jersey farms were monitored from 2004 to 2011 for H. halys. This proved to be a highly effective method of monitoring H. halys populations and their spread at the landscape level. The total number of brown marmorated stink bug caught in New Jersey increased exponentially during this period at a rate of 75% per year. Logistic regression estimates that 2.84 new farms are invaded each year by H. halys. The results indicate that black light traps are attractive to early season populations as well as at low population densities. Weekly trap catch data are being used to generate state-wide population distribution maps made available to farmers in weekly newsletters and online. While no economic threshold currently exists for brown marmorated stink bug, the maps provide farmers with a tool to forecast pest pressure and plan management.

Real time monitoring of powder blend bulk density for coupled feed-forward/feed-back control of a continuous direct compaction tablet manufacturing process.

Science.gov (United States)

Singh, Ravendra; Román-Ospino, Andrés D; Romañach, Rodolfo J; Ierapetritou, Marianthi; Ramachandran, Rohit

2015-11-10

The pharmaceutical industry is strictly regulated, where precise and accurate control of the end product quality is necessary to ensure the effectiveness of the drug products. For such control, the process and raw materials variability ideally need to be fed-forward in real time into an automatic control system so that a proactive action can be taken before it can affect the end product quality. Variations in raw material properties (e.g., particle size), feeder hopper level, amount of lubrication, milling and blending action, applied shear in different processing stages can affect the blend density significantly and thereby tablet weight, hardness and dissolution. Therefore, real time monitoring of powder bulk density variability and its incorporation into the automatic control system so that its effect can be mitigated proactively and efficiently is highly desired. However, real time monitoring of powder bulk density is still a challenging task because of different level of complexities. In this work, powder bulk density which has a significant effect on the critical quality attributes (CQA's) has been monitored in real time in a pilot-plant facility, using a NIR sensor. The sensitivity of the powder bulk density on critical process parameters (CPP's) and CQA's has been analyzed and thereby feed-forward controller has been designed. The measured signal can be used for feed-forward control so that the corrective actions on the density variations can be taken before they can influence the product quality. The coupled feed-forward/feed-back control system demonstrates improved control performance and improvements in the final product quality in the presence of process and raw material variations. Copyright © 2015 Elsevier B.V. All rights reserved.

The Effect of Earthworm (Lumbricus terrestris L.) Population Density and Soil Water Content Interactions on Nitrous Oxide Emissions from Agricultural Soils

International Nuclear Information System (INIS)

Evers, A.K.; Gordon, A.M.; Thevathasan, N.V.; Demers, T.A.

2010-01-01

Earthworms may have an influence on the production of N 2 O, a greenhouse gas, as a result of the ideal environment contained in their gut and casts for denitrifier bacteria. The objective of this study was to determine the relationship between earthworm (Lumbricus terrestris L.) population density, soil water content and N 2 O emissions in a controlled greenhouse experiment based on population densities (90 to 270 individuals m-2) found at the Guelph Agroforestry Research Station (GARS) from 1997 to 1998. An experiment conducted at considerably higher than normal densities of earthworms revealed a significant relationship between earthworm density, soil water content and N 2 O emissions, with mean emissions increasing to 43.5 g ha-1day-1 at 30 earthworms 0.0333 m-2 at 35% soil water content. However, a second experiment, based on the density of earthworms at GARS, found no significant difference in N 2 O emissions (5.49 to 6.99 g ha-1day-1) aa a result of density and 31% soil water content

A dynamic urban air pollution population exposure assessment study using model and population density data derived by mobile phone traffic

Science.gov (United States)

Gariazzo, Claudio; Pelliccioni, Armando; Bolignano, Andrea

2016-04-01

A dynamic city-wide air pollution exposure assessment study has been carried out for the urban population of Rome, Italy, by using time resolved population distribution maps, derived by mobile phone traffic data, and modelled air pollutants (NO2, O3 and PM2.5) concentrations obtained by an integrated air dispersion modelling system. More than a million of persons were tracked during two months (March and April 2015) for their position within the city and its surroundings areas, with a time resolution of 15 min and mapped over an irregular grid system with a minimum resolution of 0.26 × 0.34 Km2. In addition, demographics information (as gender and age ranges) were available in a separated dataset not connected with the total population one. Such BigData were matched in time and space with air pollution model results and then used to produce hourly and daily resolved cumulative population exposures during the studied period. A significant mobility of population was identified with higher population densities in downtown areas during daytime increasing of up to 1000 people/Km2 with respect to nigh-time one, likely produced by commuters, tourists and working age population. Strong variability (up to ±50% for NO2) of population exposures were detected as an effect of both mobility and time/spatial changing in pollutants concentrations. A comparison with the correspondent stationary approach based on National Census data, allows detecting the inability of latter in estimating the actual variability of population exposure. Significant underestimations of the amount of population exposed to daily PM2.5 WHO guideline was identified for the Census approach. Very small differences (up to a few μg/m3) on exposure were detected for gender and age ranges population classes.

Dealing with incomplete and variable detectability in multi-year, multi-site monitoring of ecological populations

Science.gov (United States)

Converse, Sarah J.; Royle, J. Andrew; Gitzen, Robert A.; Millspaugh, Joshua J.; Cooper, Andrew B.; Licht, Daniel S.

2012-01-01

An ecological monitoring program should be viewed as a component of a larger framework designed to advance science and/or management, rather than as a stand-alone activity. Monitoring targets (the ecological variables of interest; e.g. abundance or occurrence of a species) should be set based on the needs of that framework (Nichols and Williams 2006; e.g. Chapters 2–4). Once such monitoring targets are set, the subsequent step in monitoring design involves consideration of the field and analytical methods that will be used to measure monitoring targets with adequate accuracy and precision. Long-term monitoring programs will involve replication of measurements over time, and possibly over space; that is, one location or each of multiple locations will be monitored multiple times, producing a collection of site visits (replicates). Clearly this replication is important for addressing spatial and temporal variability in the ecological resources of interest (Chapters 7–10), but it is worth considering how this replication can further be exploited to increase the effectiveness of monitoring. In particular, defensible monitoring of the majority of animal, and to a lesser degree plant, populations and communities will generally require investigators to account for imperfect detection (Chapters 4, 18). Raw indices of population state variables, such as abundance or occupancy (sensu MacKenzie et al. 2002), are rarely defensible when detection probabilities are challenges associated with estimating detection probabilities (e.g. McKelvey and Pearson 2001, Johnson 2008), we do not attempt to resolve this debate here. Rather, we are more apt to agree with MacKenzie and Kendall (2002) that the burden of proof ought to be on the assertion that detection probabilities are constant. Furthermore, given the wide variety of field methods available for estimating detection probabilities and the inability for an investigator to know, a priori, if detection probabilities will be

Monitoring Population Evolution in the Pearl River Delta from 2000 TO 2010

Science.gov (United States)

Yu, S.; Liu, F.; Zhang, Z.

2018-04-01

On behalf of more populous and developed regions in China, urban agglomerations have become important carries loading active economic activities and generous social benefits, and experienced sharper population increase, which results in great threat on local eco-environment construction. Therefore, exact and detailed population monitoring and analyzing, especially on the long sequence and multi frequency, is of great significance. The nighttime light time-series (NLT) products has been proven to be one of the most useful remotely sensed imagery to acquire persons at 1 km × 1 km scales. However, the existed problems, such as light saturation and blooming, greatly limit the accuracy of estimated results. Furthermore, it's difficult to spatialize population at km2 level due to the lack of basic data in non-census years. In order to solve all problems mentioned above, the populous Pearl River Delta was selected as the study area. A new residential extent extraction index (REEI) was proposed to solve light saturation and blooming problems. Population spatialization methods in census and non-census years were applied to acquire detailed population distribution from 2000 to 2010. Results showed the feasibility of the proposed methods in this work. During the decade, population was denser in the central PRD and sparser in the eastern, western and northern PRD. The speed of population increase was various in nine cities, but faster in 2000-2005 than 2005-2010.

Effect of Physicochemical Characteristics of Soil on Population Density of Arbuscular Mycorrhizal Fungi in the Roots of Grapevine in Urmia

Directory of Open Access Journals (Sweden)

A. Mahdavi Bileh Savar

2015-01-01

Full Text Available Relationship of is one of the most useful interactions in terrestrial ecosystems that its positive effects on growth, physiology and ecology of different plants has been documented. This study investigated the relationship between important physicochemical characteristics of soils such as pH, electrical conductivity (EC, soil texture, organic carbon percentage, soil potassium percentage and the amount of accessible phosphorus with population of mycorrhizal fungi. After dividing the study region into four areas, 43 samples of soil were collected. The results of statistical analysis on physico-chemical characteristics of soil and their relation with population density of spores of arbuscular mycorrhizal fungi showed that there was a negative correlation between electrical conductivity (EC, pH, clay percent, and percent of soil available phosphorus, potassium percent, and percentage of organic carbon with the mean number of fungi. There were positive correlations between silt and sand percentages and mean number of spores present in the soil. Based on the coefficien of determination and based on study conditions, the best model for the rhizosphere was found tobe the one in wich available phosphorus percent of soil was the independent variable, and mean population of fungi as the dependant variable. The correlation between available phosphorus percent in soil samples with average fungi population density negative (P<0/05, but there was not a meaningful correlation between other traits and population density of fungi

Sustainable Seas Student Intertidal Monitoring Project, Duxbury Reef, Bolinas, CA

Science.gov (United States)

Soave, K.; Dean, A.; Prescutti, K.; Ball, O.; Chang, E.; Darakananda, K.; Jessup, K.; Poutian, J.; Schwalbe, H.; Storm, E.

2008-12-01

The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program and Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal ecology, interpretation and monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects (A and B), and using randomly determined points within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will analyze the population densities of aggregating anemones, Anthopleura elegantissima, for seasonal abundance variations as well as long-term population trends. We will also follow the seasonal and long-term population fluctuations of red algal turf, Endocladia muricata and Gelidium coulteri, and black turban snails, Tegula funebralis. Comparing populations of turf algae and the herbivorous black turban snails gathered before and after the November 7, 2007 San Francisco Bay oil spill shows very little impact on the Duxbury Reef intertidal inhabitants. Future analyses will

Idaho Habitat/Natural Production Monitoring Part I, 1995 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Hall-Griswold, J.A.; Petrosky, C.E. (Idaho Department of Fish and Game, Boise, ID)

1996-12-01

The Idaho Department of Fish and Game (IDFG) has been monitoring trends in juvenile spring and summer chinook salmon, Oncorhynchus tshawytscha, and steelhead trout, O. mykiss, populations in the Salmon, Clearwater, and lower Snake River drainages for the past 12 years. This work is the result of a program to protect, mitigate, and enhance fish and wildlife affected by the development and operation of hydroelectric power plants on the Columbia River. Project 91-73, Idaho Natural Production Monitoring, consists of two subprojects: General Monitoring and Intensive Monitoring. This report updates and summarizes data through 1995 for the General Parr Monitoring (GPM) database to document status and trends of classes of wild and natural chinook salmon and steelhead trout populations. A total of 281 stream sections were sampled in 1995 to monitor trends in spring and summer chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss parr populations in Idaho. Percent carrying capacity and density estimates were summarized for 1985--1995 by different classes of fish: wild A-run steelhead trout, wild B-run steelhead trout, natural A-run steelhead trout, natural B-run steelhead trout, wild spring and summer chinook salmon, and natural spring and summer chinook salmon. The 1995 data were also summarized by subbasins as defined in Idaho Department of Fish and Game`s 1992--1996 Anadromous Fish Management Plan.

Idaho habitat/natural production monitoring: Part 1. Annual report 1995

International Nuclear Information System (INIS)

Hall-Griswold, J.A.; Petrosky, C.E.

1996-11-01

The Idaho Department of Fish and Game (IDFG) has been monitoring trends in juvenile spring and summer chinook salmon, Oncorhynchus tshawytscha, and steelhead trout, O. mykiss, populations in the Salmon, Clearwater, and lower Snake River drainages for the past 12 years. This work is the result of a program to protect, mitigate, and enhance fish and wildlife affected by the development and operation of hydroelectric power plants on the Columbia River. Project 91-73, Idaho Natural Production Monitoring, consists of two subprojects: General Monitoring and Intensive Monitoring. This report updates and summarizes data through 1995 for the General Parr Monitoring (GPM) database to document status and trends of classes of wild and natural chinook salmon and steelhead trout populations. A total of 281 stream sections were sampled in 1995 to monitor trends in spring and summer chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss parr populations in Idaho. Percent carrying capacity and density estimates were summarized for 1985--1995 by different classes of fish: wild A-run steelhead trout, wild B-run steelhead trout, natural A-run steelhead trout, natural B-run steelhead trout, wild spring and summer chinook salmon, and natural spring and summer chinook salmon. The 1995 data were also summarized by subbasins as defined in Idaho Department of Fish and Game's 1992--1996 Anadromous Fish Management Plan

Seasonal population dynamics of Homalodisca vitripennis (Hemiptera: Cicadellidae) in sweet orange trees maintained under continuous deficit irrigation.

Science.gov (United States)

Krugner, Rodrigo; Groves, Russell L; Johnson, Marshall W; Flores, Arnel P; Hagler, James R; Morse, Joseph G

2009-06-01

A 2-yr study was conducted in a citrus orchard (Citrus sinensis L. Osbeck cultivar Valencia) to determine the influence of plant water stress on the population dynamics of glassy-winged sharpshooter, Homalodisca vitripennis (Germar). Experimental treatments included irrigation at 100% of the crop evapotranspiration rate (ET(c)) and continuous deficit-irrigation regimens at 80 and 60% ET(c). Microclimate and plant conditions monitored included temperature and humidity in the tree canopy, leaf surface temperature, water potential, and fruit quality and yield. Glassy-winged sharpshooter population densities and activity were monitored weekly by a combination of visual inspections, beat net sampling, and trapping. Glassy-winged sharpshooter populations were negatively affected by severe plant water stress; however, population densities were not linearly related to decreasing water availability in plants. Citrus trees irrigated at 60% ET(c) had significantly warmer leaves, lower xylem water potential, and consequently hosted fewer glassy-winged sharpshooter eggs, nymphs, and adults than trees irrigated at 80% ET(c). Citrus trees irrigated at 100% ET(c) hosted similar numbers of glassy-winged sharpshooter stages as trees irrigated at 60% ET(c) and a lower number of glassy-winged sharpshooter nymphs than the 80% ET(c) treatment, specifically during the nymphal density peak in mid-April to early July. Irrigation treatments did not affect populations of monitored natural enemies. Although the adult glassy-winged sharpshooter population was reduced, on average, by 50% in trees under severe water stress, the total number of fruit and number of fruit across several fruit grade categories were significantly lower in the 60% ET(c) than in the 80 and 100% ET(c) irrigation treatments.

Optimal city size and population density for the 21st century.

Science.gov (United States)

Speare A; White, M J

1990-10-01

The thesis that large scale urban areas result in greater efficiency, reduced costs, and a better quality of life is reexamined. The environmental and social costs are measured for different scales of settlement. The desirability and perceived problems of a particular place are examined in relation to size of place. The consequences of population decline are considered. New York city is described as providing both opportunities in employment, shopping, and cultural activities as well as a high cost of living, crime, and pollution. The historical development of large cities in the US is described. Immigration has contributed to a greater concentration of population than would have otherwise have occurred. The spatial proximity of goods and services argument (agglomeration economies) has changed with advancements in technology such as roads, trucking, and electronic communication. There is no optimal city size. The overall effect of agglomeration can be assessed by determining whether the markets for goods and labor are adequate to maximize well-being and balance the negative and positive aspects of urbanization. The environmental costs of cities increase with size when air quality, water quality, sewage treatment, and hazardous waste disposal is considered. Smaller scale and lower density cities have the advantages of a lower concentration of pollutants. Also, mobilization for program support is easier with homogenous population. Lower population growth in large cities would contribute to a higher quality of life, since large metropolitan areas have a concentration of immigrants, younger age distributions, and minority groups with higher than average birth rates. The negative consequences of decline can be avoided if reduction of population in large cities takes place gradually. For example, poorer quality housing can be removed for open space. Cities should, however, still attract all classes of people with opportunities equally available.

City density and CO_2 efficiency

International Nuclear Information System (INIS)

Gudipudi, Ramana; Fluschnik, Till; Ros, Anselmo García Cantú; Walther, Carsten; Kropp, Jürgen P.

2016-01-01

Cities play a vital role in the global climate change mitigation agenda. City population density is one of the key factors that influence urban energy consumption and the subsequent GHG emissions. However, previous research on the relationship between population density and GHG emissions led to contradictory results due to urban/rural definition conundrum and the varying methodologies for estimating GHG emissions. This work addresses these ambiguities by employing the City Clustering Algorithm (CCA) and utilizing the gridded CO_2 emissions data. Our results, derived from the analysis of all inhabited areas in the US, show a sub-linear relationship between population density and the total emissions (i.e. the sum of on-road and building emissions) on a per capita basis. Accordingly, we find that doubling the population density would entail a reduction in the total CO_2 emissions in buildings and on-road sectors typically by at least 42%. Moreover, we find that population density exerts a higher influence on on-road emissions than buildings emissions. From an energy consumption point of view, our results suggest that on-going urban sprawl will lead to an increase in on-road energy consumption in cities and therefore stresses the importance of developing adequate local policy measures to limit urban sprawl. - Highlights: •We use gridded population, land use and CO_2 emissions data. •We attribute building and on-road sectoral emissions to populated settlements. •We apply CCA to identify unique city extents and population densities. •Doubling the population density increases CO_2 efficiency typically by 42%. •Population density has more influence on-road CO_2 efficiency than buildings sector.

Relationships between nutrient enrichment, pleurocerid snail density and trematode infection rate in streams

Science.gov (United States)

Ciparis, Serena; Iwanowicz, Deborah D.; Voshell, J. Reese

2013-01-01

Summary 1. Nutrient enrichment is a widespread environmental problem in freshwater ecosystems. Eutrophic conditions caused by nutrient enrichment may result in a higher prevalence of infection by trematode parasites in host populations, due to greater resource availability for the molluscan first intermediate hosts. 2. This study examined relationships among land use, environmental variables indicating eutrophication, population density of the pleurocerid snail, Leptoxis carinata, and trematode infections. Fifteen study sites were located in streams within the Shenandoah River catchment (Virginia, U.S.A.), where widespread nutrient enrichment has occurred. 3. Snail population density had a weak positive relationship with stream water nutrient concentration. Snail population density also increased as human activities within stream catchments increased, but density did not continue to increase in catchments where anthropogenic disturbance was greatest. 4. Cercariae from five families of trematodes were identified in L. carinata, and infection rate was generally low (<10%). Neither total infection rate nor the infection rate of individual trematode types showed a positive relationship with snail population density, nutrients or land use. 5. There were statistically significant but weak relationships between the prevalence of infection by two trematode families and physical and biological variables. The prevalence of Notocotylidae was positively related to water depth, which may be related to habitat use by definitive hosts. Prevalence of Opecoelidae had a negative relationship with orthophosphate concentration and a polynomial relationship with chlorophyll a concentration. Transmission of Opecoelid trematodes between hosts may be inhibited by eutrophic conditions. 6. Leptoxis carinata appears to be a useful species for monitoring the biological effects of eutrophication and investigating trematode transmission dynamics in lotic systems.

Population densities and rate coefficients for electron impact excitation in singly ionized oxygen

International Nuclear Information System (INIS)

Awakowicz, P.; Behringer, K.

1995-01-01

In non-LTE arc plasmas, O II excited state number densities were measured relative to the O II ground and metastable states. The results were compared with collisional-radiative code calculations on the basis of the JET ADAS programs. Stationary He plasmas with small oxygen admixtures, generated in a 5 mm diameter cascade arc chamber (pressures 13-70 hPa, arc current 150 A), were investigated spectroscopically in the visible and the VUV spectral range. The continuum of a 2 mm diameter pure He arc (atmospheric pressure, current 100 A) served for calibration of the VUV system response. Plasma diagnostics on the basis of Hβ Stark broadening yielded electron densities between 2.4 x 10 14 and 2.0 x 10 15 cm -3 for the low-pressure O II mixture plasmas. The agreement of measured and calculated excited state populations is generally very satisfactory, thus confirming the rate coefficients in the code. This is of particular interest in this intermediate region between corona balance and LTE, where many atomic data are required in the simulation. Clear indications were found for the diffusion of metastables lowering their number densities significantly below their statistical values. (author)

Effects of habitat size and quality on equilibrium density and extinction time of Sorex araneus populations

NARCIS (Netherlands)

Klok, C.; Roos, de A.M.

1998-01-01

1. The effects of changes in habitat size and quality on the expected population density and the expected time to extinction of Sorex araneus are studied by means of mathematical models that incorporate demographic stochasticity. 2. Habitat size is characterized by the number of territories, while

Monitoring of populations and productivity of seabirds at St. George Island, Cape Peirce, and Bluff, Alaska, 1989. Final report

International Nuclear Information System (INIS)

Mendenhall, V.M.

1991-04-01

In recent years, although descriptive studies have continued, the emphasis on population monitoring of seabirds has increased. Commercial uses of the Continental Shelf of the Bering and Chukchi Seas, including oil and gas development, subsurface placer mining, and commercial fishing, carry the potential for adverse pressures on seabird populations. Populations and productivity of seabirds were monitored in 1989 at three Bering Sea colonies: St. George, Cape Peirce, and Bluff. Murres and black-legged kittiwakes were monitored at all colonies to facilitate intercolony comparisons. These species were selected because they are relatively easy to study, numerous, sensitive to potential impacts of development, and widely distributed. Red legged kittiwakes also were monitored at St. George because of concern for the world status of the species. Methods were standardized among the three colonies to facilitate comparisons among colonies and years. Observations of productivity began at the time nests were established and continued until most young had fledged. Kittiwake nests and murre breeding sites used for estimation of productivity were mapped on photographs or sketches and the fate of each was recorded

Failure to Respond to Food Resource Decline Has Catastrophic Consequences for Koalas in a High-Density Population in Southern Australia.

Directory of Open Access Journals (Sweden)

Desley A Whisson

Full Text Available Understanding the ability of koalas to respond to changes in their environment is critical for conservation of the species and their habitat. We monitored the behavioural response of koalas to declining food resources in manna gum (Eucalyptus viminalis woodland at Cape Otway, Victoria, Australia, from September 2011 to November 2013. Over this period, koala population density increased from 10.1 to 18.4 koalas.ha-1. As a result of the high browsing pressure of this population, manna gum canopy condition declined with 71.4% manna gum being completely or highly defoliated in September 2013. Despite declining food resources, radio collared koalas (N = 30 exhibited high fidelity to small ranges (0.4-1.2 ha. When trees became severely defoliated in September 2013, koalas moved relatively short distances from their former ranges (mean predicted change in range centroid = 144 m and remained in areas of 0.9 to 1.0 ha. This was despite the high connectivity of most manna gum woodland, and close proximity of the study site (< 3 km to the contiguous mixed forest of the Great Otway National Park. Limited movement had catastrophic consequences for koalas with 71% (15/21 of radio collared koalas dying from starvation or being euthanased due to their poor condition between September and November 2013.

Trapping Elusive Cats: Using Intensive Camera Trapping to Estimate the Density of a Rare African Felid.

Science.gov (United States)

Brassine, Eléanor; Parker, Daniel

2015-01-01

Camera trapping studies have become increasingly popular to produce population estimates of individually recognisable mammals. Yet, monitoring techniques for rare species which occur at extremely low densities are lacking. Additionally, species which have unpredictable movements may make obtaining reliable population estimates challenging due to low detectability. Our study explores the effectiveness of intensive camera trapping for estimating cheetah (Acinonyx jubatus) numbers. Using both a more traditional, systematic grid approach and pre-determined, targeted sites for camera placement, the cheetah population of the Northern Tuli Game Reserve, Botswana was sampled between December 2012 and October 2013. Placement of cameras in a regular grid pattern yielded very few (n = 9) cheetah images and these were insufficient to estimate cheetah density. However, pre-selected cheetah scent-marking posts provided 53 images of seven adult cheetahs (0.61 ± 0.18 cheetahs/100 km²). While increasing the length of the camera trapping survey from 90 to 130 days increased the total number of cheetah images obtained (from 53 to 200), no new individuals were recorded and the estimated population density remained stable. Thus, our study demonstrates that targeted camera placement (irrespective of survey duration) is necessary for reliably assessing cheetah densities where populations are naturally very low or dominated by transient individuals. Significantly our approach can easily be applied to other rare predator species.

Trapping Elusive Cats: Using Intensive Camera Trapping to Estimate the Density of a Rare African Felid

Science.gov (United States)

Brassine, Eléanor; Parker, Daniel

2015-01-01

Camera trapping studies have become increasingly popular to produce population estimates of individually recognisable mammals. Yet, monitoring techniques for rare species which occur at extremely low densities are lacking. Additionally, species which have unpredictable movements may make obtaining reliable population estimates challenging due to low detectability. Our study explores the effectiveness of intensive camera trapping for estimating cheetah (Acinonyx jubatus) numbers. Using both a more traditional, systematic grid approach and pre-determined, targeted sites for camera placement, the cheetah population of the Northern Tuli Game Reserve, Botswana was sampled between December 2012 and October 2013. Placement of cameras in a regular grid pattern yielded very few (n = 9) cheetah images and these were insufficient to estimate cheetah density. However, pre-selected cheetah scent-marking posts provided 53 images of seven adult cheetahs (0.61 ± 0.18 cheetahs/100km²). While increasing the length of the camera trapping survey from 90 to 130 days increased the total number of cheetah images obtained (from 53 to 200), no new individuals were recorded and the estimated population density remained stable. Thus, our study demonstrates that targeted camera placement (irrespective of survey duration) is necessary for reliably assessing cheetah densities where populations are naturally very low or dominated by transient individuals. Significantly our approach can easily be applied to other rare predator species. PMID:26698574

Trapping Elusive Cats: Using Intensive Camera Trapping to Estimate the Density of a Rare African Felid.

Directory of Open Access Journals (Sweden)

Eléanor Brassine

Full Text Available Camera trapping studies have become increasingly popular to produce population estimates of individually recognisable mammals. Yet, monitoring techniques for rare species which occur at extremely low densities are lacking. Additionally, species which have unpredictable movements may make obtaining reliable population estimates challenging due to low detectability. Our study explores the effectiveness of intensive camera trapping for estimating cheetah (Acinonyx jubatus numbers. Using both a more traditional, systematic grid approach and pre-determined, targeted sites for camera placement, the cheetah population of the Northern Tuli Game Reserve, Botswana was sampled between December 2012 and October 2013. Placement of cameras in a regular grid pattern yielded very few (n = 9 cheetah images and these were insufficient to estimate cheetah density. However, pre-selected cheetah scent-marking posts provided 53 images of seven adult cheetahs (0.61 ± 0.18 cheetahs/100 km². While increasing the length of the camera trapping survey from 90 to 130 days increased the total number of cheetah images obtained (from 53 to 200, no new individuals were recorded and the estimated population density remained stable. Thus, our study demonstrates that targeted camera placement (irrespective of survey duration is necessary for reliably assessing cheetah densities where populations are naturally very low or dominated by transient individuals. Significantly our approach can easily be applied to other rare predator species.

Preferential enrichment of large-sized very low density lipoprotein populations with transferred cholesteryl esters

International Nuclear Information System (INIS)

Eisenberg, S.

1985-01-01

The effect of lipid transfer proteins on the exchange and transfer of cholesteryl esters from rat plasma HDL2 to human very low (VLDL) and low density (LDL) lipoprotein populations was studied. The use of a combination of radiochemical and chemical methods allowed separate assessment of [ 3 H]cholesteryl ester exchange and of cholesteryl ester transfer. VLDL-I was the preferred acceptor for transferred cholesteryl esters, followed by VLDL-II and VLDL-III. LDL did not acquire cholesteryl esters. The contribution of exchange of [ 3 H]cholesteryl esters to total transfer was highest for LDL and decreased in reverse order along the VLDL density range. Inactivation of lecithin: cholesterol acyltransferase (LCAT) and heating the HDL2 for 60 min at 56 degrees C accelerated transfer and exchange of [ 3 H]cholesteryl esters. Addition of lipid transfer proteins increased cholesterol esterification in all systems. The data demonstrate that large-sized, triglyceride-rich VLDL particles are preferred acceptors for transferred cholesteryl esters. It is suggested that enrichment of very low density lipoproteins with cholesteryl esters reflects the triglyceride content of the particles

Effects of mental workload on physiological and subjective responses during traffic density monitoring: A field study.

Science.gov (United States)

Fallahi, Majid; Motamedzade, Majid; Heidarimoghadam, Rashid; Soltanian, Ali Reza; Miyake, Shinji

2016-01-01

This study evaluated operators' mental workload while monitoring traffic density in a city traffic control center. To determine the mental workload, physiological signals (ECG, EMG) were recorded and the NASA-Task Load Index (TLX) was administered for 16 operators. The results showed that the operators experienced a larger mental workload during high traffic density than during low traffic density. The traffic control center stressors caused changes in heart rate variability features and EMG amplitude, although the average workload score was significantly higher in HTD conditions than in LTD conditions. The findings indicated that increasing traffic congestion had a significant effect on HR, RMSSD, SDNN, LF/HF ratio, and EMG amplitude. The results suggested that when operators' workload increases, their mental fatigue and stress level increase and their mental health deteriorate. Therefore, it maybe necessary to implement an ergonomic program to manage mental health. Furthermore, by evaluating mental workload, the traffic control center director can organize the center's traffic congestion operators to sustain the appropriate mental workload and improve traffic control management. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Effect of Population Density on Timing of Oviposition and Brood Size Reduction in the Burying Beetle Nicrophorus pustulatus Herschel (Coleoptera: Silphidae

Directory of Open Access Journals (Sweden)

Claudia M. Rauter

2012-01-01

Full Text Available Burying beetles (Nicrophorus spp. bury small carcasses to feed their larvae. Carcasses are a limited, high-quality resource and contests over carcasses become more frequent with increasing population density. Successful beetles kill eggs and larvae present on carcass. In response, females should accelerate oviposition, while offspring development should increase to minimize mortality. Both value of a carcass and frequency of contests decrease as larvae develop. If overproduction of offspring is an insurance against high mortality, females should reduce brood size as carcass value declines. Testing our predictions, we reared female burying beetles, Nicrophorus pustulatus, at high and low densities and compared oviposition and brood reduction. High-density females delayed oviposition, suggesting that high population density imposes nutritional and/or physiological stress. Females responded to the physiological constraints and the potentially high mortality rates of eggs and newly hatched larvae by lengthening oviposition period and changing brood reduction rate.

Multiscale approach to pest insect monitoring: random walks, pattern formation, synchronization, and networks.

Science.gov (United States)

Petrovskii, Sergei; Petrovskaya, Natalia; Bearup, Daniel

2014-09-01

Pest insects pose a significant threat to food production worldwide resulting in annual losses worth hundreds of billions of dollars. Pest control attempts to prevent pest outbreaks that could otherwise destroy a sward. It is good practice in integrated pest management to recommend control actions (usually pesticides application) only when the pest density exceeds a certain threshold. Accurate estimation of pest population density in ecosystems, especially in agro-ecosystems, is therefore very important, and this is the overall goal of the pest insect monitoring. However, this is a complex and challenging task; providing accurate information about pest abundance is hardly possible without taking into account the complexity of ecosystems' dynamics, in particular, the existence of multiple scales. In the case of pest insects, monitoring has three different spatial scales, each of them having their own scale-specific goal and their own approaches to data collection and interpretation. In this paper, we review recent progress in mathematical models and methods applied at each of these scales and show how it helps to improve the accuracy and robustness of pest population density estimation. Copyright © 2014 Elsevier B.V. All rights reserved.

Safety Evaluation of an Automated Remote Monitoring System for Heart Failure in an Urban, Indigent Population.

Science.gov (United States)

Gross-Schulman, Sandra; Sklaroff, Laura Myerchin; Hertz, Crystal Coyazo; Guterman, Jeffrey J

2017-12-01

Heart Failure (HF) is the most expensive preventable condition, regardless of patient ethnicity, race, socioeconomic status, sex, and insurance status. Remote telemonitoring with timely outpatient care can significantly reduce avoidable HF hospitalizations. Human outreach, the traditional method used for remote monitoring, is effective but costly. Automated systems can potentially provide positive clinical, fiscal, and satisfaction outcomes in chronic disease monitoring. The authors implemented a telephonic HF automated remote monitoring system that utilizes deterministic decision tree logic to identify patients who are at risk of clinical decompensation. This safety study evaluated the degree of clinical concordance between the automated system and traditional human monitoring. This study focused on a broad underserved population and demonstrated a safe, reliable, and inexpensive method of monitoring patients with HF.

A test of density-dependent pollination within three populations of endangered Pentachaeta lyonii

Directory of Open Access Journals (Sweden)

Jocelyn R. Holt

2014-02-01

Full Text Available A major concern with endangered plants is that they might attract insufficient numbers of pollinators, produce low numbers of seeds, and decline towards extinction. We examined effects of density as it varied within populations on the pollination of Pentachaeta lyonii, an endangered species that requires pollinators for seed set. Generalist bee-flies and bees were abundant pollinators at three sites for two years. Per-capita visitation rates did not decline at sparse points or for plants placed on the order of 10 m away from other flowering individuals. Seed production was not pollinator-limited within patches, but seed set was low beyond 10 m from neighbours. Considering prior findings, factors such as habitat loss, competition with alien plants, and poor establishment of new populations likely contribute to the rarity of P. lyonii more than pollination failure.

National Surveys of Population Health: Big Data Analytics for Mobile Health Monitors.

Science.gov (United States)

Schatz, Bruce R

2015-12-01

At the core of the healthcare crisis is fundamental lack of actionable data. Such data could stratify individuals within populations to predict which persons have which outcomes. If baselines existed for all variations of all conditions, then managing health could be improved by matching the measuring of individuals to their cohort in the population. The scale required for complete baselines involves effective National Surveys of Population Health (NSPH). Traditionally, these have been focused upon acute medicine, measuring people to contain the spread of epidemics. In recent decades, the focus has moved to chronic conditions as well, which require smaller measures over longer times. NSPH have long utilized quality of life questionnaires. Mobile Health Monitors, where computing technologies eliminate manual administration, provide richer data sets for health measurement. Older technologies of telephone interviews will be replaced by newer technologies of smartphone sensors to provide deeper individual measures at more frequent timings across larger-sized populations. Such continuous data can provide personal health records, supporting treatment guidelines specialized for population cohorts. Evidence-based medicine will become feasible by leveraging hundreds of millions of persons carrying mobile devices interacting with Internet-scale services for Big Data Analytics.

The influence of neighbourhood socio-demographic factors on densities of free-roaming cat populations in an urban ecosystem in Israel

NARCIS (Netherlands)

Finkler, H.; Hatna, E.; Terkel, J.

2011-01-01

Free-roaming cat populations are abundant in many urban ecosystems worldwide. Their management is necessary for reasons of public health, risk of wildlife predation and cat welfare related to their high densities. Trap-neuter-return (TNR) programs are now the main cat population control strategy in

Mosquito population dynamics during the construction of Three Gorges Dam in Yangtze River, China.

Science.gov (United States)

Guo, Yuhong; Lai, ShengJie; Zhang, Jing; Liu, Qiyong; Zhang, Huaiqing; Ren, Zhoupeng; Mao, Deqiang; Luo, Chao; He, Yuanyuan; Wu, Haixia; Li, Guichang; Ren, Dongsheng; Liu, Xiaobo; Chang, Zhaorui

2018-06-01

Mosquitoes are responsible for spreading many diseases and their populations are susceptible to environmental changes. The ecosystems in the Three Gorges Region were probably altered because of changes to the environment during the construction of the Three Gorges Dam (TGD), the world's largest hydroelectric dam by generating capacity. We selected three sites at which to monitor the mosquitoes from 1997 to 2009. We captured adult mosquitoes with battery-powered aspirators fortnightly between May and September of each year in dwellings and sheds. We identified the mosquito species, and examined changes in the species density during the TGD construction. We monitored changes in the species and density of mosquitoes in this area for 13 years during the TGD construction and collected information that could be used to support the control and prevention of mosquito-borne infections. We found that the mosquito species composition around the residential areas remained the same, and the density changed gradually during the TGD construction. The changes in the populations tended to be consistent over the years, and the densities were highest in July, and were between 3 and 5 times greater in the sheds than in the dwellings. The mosquito species and populations remained stable during the construction of the TGD. The mosquito density may have increased as the reservoir filled, and may have decreased during the clean-up work. Clean-up work may be an effective way to control mosquitoes and prevent mosquito-borne diseases. Copyright © 2018. Published by Elsevier B.V.

Toward objective monitoring of ingestive behavior in free-living population.

Science.gov (United States)

Sazonov, Edward S; Schuckers, Stephanie A C; Lopez-Meyer, Paulo; Makeyev, Oleksandr; Melanson, Edward L; Neuman, Michael R; Hill, James O

2009-10-01

Understanding of eating behaviors associated with obesity requires objective and accurate monitoring of food intake patterns. Accurate methods are available for measuring total energy expenditure and its components in free-living populations, but methods for measuring food intake in free-living people are far less accurate and involve self-reporting or subjective monitoring. We suggest that chews and swallows can be used for objective monitoring of ingestive behavior. This hypothesis was verified in a human study involving 20 subjects. Chews and swallows were captured during periods of quiet resting, talking, and meals of varying size. The counts of chews and swallows along with other derived metrics were used to build prediction models for detection of food intake, differentiation between liquids and solids, and for estimation of the mass of ingested food. The proposed prediction models were able to detect periods of food intake with >95% accuracy and a fine time resolution of 30 s, differentiate solid foods from liquids with >91% accuracy, and predict mass of ingested food with >91% accuracy for solids and >83% accuracy for liquids. In earlier publications, we have shown that chews and swallows can be captured by noninvasive sensors that could be developed into a wearable device. Thus, the proposed methodology could lead to the development of an innovative new way of assessing human eating behavior in free-living conditions.

Density and distribution of Patella ferruginea in a Marine Protected Area (western Sardinia, Italy: Constraint analysis for population conservation

Directory of Open Access Journals (Sweden)

S. COPPA

2012-04-01

Full Text Available The endemic limpet Patella ferruginea is the most endangered invertebrate of the Mediterranean Sea. Our study examined a population of P. ferruginea in the Marine Protected Area of Penisola del Sinis - Isola di Mal di Ventre (western Sardinia, Italy. During the summer 2009, we carried out a systematic census of P. ferruginea along a 8114 m georeferenced perimeter of coast in the no take-no entry zone to assess its density, spatial distribution, and morphometric characteristics. Our aim was to provide a detailed map of the distribution of P. ferruginea and to investigate the effects of accessibility, wave exposure and slope of the coast on its occurrence. Patella ferrugineashowed the lowest mean density ever reported (0.02 ind/m and a unimodal population structure characterised by fewer females and juveniles. Accessibility had a major negative effect on the occurrence of P. ferruginea. Exposure was also an important factor in influencing its density, size composition and specimen position within the mesolittoral, while the slope had little influence. Morphometric analysis showed the dominance of the Rouxi form, while the Lamarcki form was confined to exposed sites. Our results demonstrate a highly endangered population of P. ferruginea and suggest that human pressure represents the main risk factor.

Sex differences in fingerprint ridge density in a Turkish young adult population: a sample of Baskent University.

Science.gov (United States)

Oktem, Hale; Kurkcuoglu, Ayla; Pelin, Ismail Can; Yazici, Ayse Canan; Aktaş, Gulnihal; Altunay, Fikret

2015-05-01

Fingerprints are considered to be one of the most reliable methods of identification. Identification of an individual plays a vital part of any medico-legal investigations. Dermatoglyphics is a branch of science that studies epidermal ridges and ridge patterns. Epidermal ridges are polygenic characteristics that form intrauterine 10-18 weeks and considered fully developed by the sixth month of fetal growth. Fingerprints are permanent morphological characteristics and criminal detection based on fingerprints is based on the principle that no two people can have identical fingerprints. Sex determination from fingerprints has been examined in different population. In this study we aimed to study fingerprint ridge density in Turkish population sample of Baskent University students. Fingerprints were obtained from 118 women, 88 men a total of 206 students aged between 17 and 28 years old by means of simple inking method. Fingerprints from all right and left hands fingers were collected in three different area of each. The ridges on fingerprints were counted diagonally on squares measuring 5 mm × 5 mm on radial, ulnar and inferior areas. The fingerprint ridge density in radial, ulnar and inferior areas and between sexes was compared statistically Mann Whitney U test and Friedman test. The ridge density was significantly greater in women in every region studied and in all fingers when compared to men. The fingerprint ridge density in the ulnar and radial areas of the fingerprints was significantly greater than the lower area. Fingerprint ridge density can be used by medico-legal examination for sex identification. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Uses of population census data for monitoring geographical imbalance in the health workforce: snapshots from three developing countries

Directory of Open Access Journals (Sweden)

Diallo Khassoum

2003-12-01

Full Text Available Abstract Background Imbalance in the distribution of human resources for health (HRH, eventually leading to inequities in health services delivery and population health outcomes, is an issue of social and political concern in many countries. However, the empirical evidence to support decision-making is often fragmented, and many standard data sources that can potentially produce statistics relevant to the issue remain underused, especially in developing countries. This study investigated the uses of demographic census data for monitoring geographical imbalance in the health workforce for three developing countries, as a basis for formulation of evidence-based health policy options. Methods Population-based indicators of geographical variations among HRH were extracted from census microdata samples for Kenya, Mexico and Viet Nam. Health workforce statistics were matched against international standards of occupational classification to control for cross-national comparability. Summary measures of inequality were calculated to monitor the distribution of health workers across spatial units and by occupational group. Results Strong inequalities were found in the geographical distribution of the health workforce in all three countries, with the highest densities of HRH tending to be found in the capital areas. Cross-national differences were found in the magnitude of distributional inequality according to occupational group, with health professionals most susceptible to inequitable distribution in Kenya and Viet Nam but less so in Mexico compared to their associate professional counterparts. Some discrepancies were suggested between mappings of occupational information from the raw data with the international system, especially for nursing and midwifery specializations. Conclusions The problem of geographical imbalance among HRH across countries in the developing world holds important implications at the local, national and international levels, in

Topological variability and sex differences in fingerprint ridge density in a sample of the Sudanese population.

Science.gov (United States)

Ahmed, Altayeb Abdalla; Osman, Samah

2016-08-01

Fingerprints are important biometric variables that show manifold utilities in human biology, human morphology, anthropology, and genetics. Their role in forensics as a legally admissible tool of identification is well recognized and is based on their stability following full development, individualistic characteristics, easy classification of their patterns, and uniqueness. Nevertheless, fingerprint ridge density and its variability have not been previously studied in the Sudanese population. Hence, this study was conducted to analyze the topological variability in epidermal ridge density and to assess the possibility of its application in determining sex of Sudanese Arabs. The data used for this study were prints of all 10 fingers of 200 Sudanese Arab individuals (100 men and 100 women) aged between 18 and 28 years. Fingerprint ridge density was assessed for three different areas (radial, ulnar and proximal) for all 10 fingers of each subject. Significant variability was found between the areas (p crime scenes can be useful to determine sex of Sudanese individuals based on fingerprint ridge density; furthermore, ridge density can be considered a morphological trait for individual variation in forensic anthropology. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Muon borehole detector development for use in four-dimensional tomographic density monitoring

Science.gov (United States)

Flygare, Joshua

The increase of CO2 concentrations in the atmosphere and the correlated temperature rise has initiated research into methods of carbon sequestration. One promising possibility is to store CO2 in subsurface reservoirs of porous rock. After injection, the monitoring of the injected CO2 is of paramount importance because the CO2 plume, if escaped, poses health and environmental risks. Traditionally, seismic reflection methods are the chosen method of determining changes in the reservoir density due to CO2 injection, but this is expensive and not continuous. A potential and promising alternative is to use cosmic muon tomography to determine density changes in the reservoir over a period of time. The work I have completed was the development of a muon detector that will be capable of being deployed in boreholes and perform long-term tomography of the reservoir of interest. The detector has the required dimensions, an angular resolution of approximately 2 degrees, and is robust enough to survive the caustic nature of the fluids in boreholes, as well as temperature and pressure fluctuations. The detector design is based on polystyrene scintillating rods arrayed in alternating layers. The layers, as arranged, can provide four-dimensional (4D) tomographic data to detect small changes in density at depths up to approximately 2 kilometers. Geant4, a Monte Carlo simulation code, was used to develop and optimize the detector design. Additionally, I developed a method of determining the muon flux at depth, including CO2 saturation changes in subsurface reservoirs. Preliminary experiments were performed at Pacific Northwest National Laboratory. This thesis will show the simulations I performed to determine the angular resolution and background discrimination required of the detector, the experiments to determine light transport through the polystyrene scintillating rods and fibers, and the method developed to predict muon flux changes at depth expected after injection.

Cordia dichotoma G. Forst. : Bioecology and population density

Science.gov (United States)

Rahayu, E. S.; Martin, P.; Dewi, N. K.; Kurniawan, F. H.

2017-04-01

Kendal tree is declared as an identity flora of Kendal Regency, Central Java, Indonesia. It is predicted as a rare species; most of the local people do not know the existence of this tree. The study aimed to describe some aspects of bioecology and a population density of Kendal tree. An explorative study was conducted from March to July 2016, through interview, observation, and literature review. The respondents were determined by purposive and snowball sampling methods. The data were analysed descriptively. Results showed that there were very limited numbers (only five trees) of Kendal tree throughout Kendal Regency. The species was identified as Cordia dichotoma G. Forst. The tree is 3-15 m in height. The leaves are simple and arranged spirally, inflorescence dichotomous, bisexual, with five gamosepalous and gamopetalous. Generative reproduction occurred at a low rate. The tree grew optimally in a dusty, sandy loam soil, pH 6.0-6.5 with a temperature ranged from 27-34 °C, a light intensity of 450-1580 lux, and an altitude of about 10 meters above sea level. In conclusion, C. dichotoma is a rare plant in Kendal Regency. This plant needs an alternative method of propagation, regeneration and conservation using in vitro technique.

Changes in home range sizes and population densities of carnivore species along the natural to urban habitat gradient

Czech Academy of Sciences Publication Activity Database

Šálek, Martin; Drahníková, L.; Tkadlec, Emil

2015-01-01

Roč. 45, č. 1 (2015), s. 1-14 ISSN 0305-1838 Institutional support: RVO:68081766 Keywords : Carnivores * home range size * natural–urban gradient * population density * review Subject RIV: EG - Zoology Impact factor: 4.116, year: 2015

Growth rates and variances of unexploited wolf populations in dynamic equilibria

Science.gov (United States)

Mech, L. David; Fieberg, John

2015-01-01

Several states have begun harvesting gray wolves (Canis lupus), and these states and various European countries are closely monitoring their wolf populations. To provide appropriate perspective for determining unusual or extreme fluctuations in their managed wolf populations, we analyzed natural, long-term, wolf-population-density trajectories totaling 130 years of data from 3 areas: Isle Royale National Park in Lake Superior, Michigan, USA; the east-central Superior National Forest in northeastern Minnesota, USA; and Denali National Park, Alaska, USA. Ratios between minimum and maximum annual sizes for 2 mainland populations (n = 28 and 46 yr) varied from 2.5–2.8, whereas for Isle Royale (n = 56 yr), the ratio was 6.3. The interquartile range (25th percentile, 75th percentile) for annual growth rates, Nt+1/Nt, was (0.88, 1.14), (0.92, 1.11), and (0.86, 1.12) for Denali, Superior National Forest, and Isle Royale respectively. We fit a density-independent model and a Ricker model to each time series, and in both cases we considered the potential for observation error. Mean growth rates from the density-independent model were close to 0 for all 3 populations, with 95% credible intervals including 0. We view the estimated model parameters, including those describing annual variability or process variance, as providing useful summaries of the trajectories of these populations. The estimates of these natural wolf population parameters can serve as benchmarks for comparison with those of recovering wolf populations. Because our study populations were all from circumscribed areas, fluctuations in them represent fluctuations in densities (i.e., changes in numbers are not confounded by changes in occupied area as would be the case with populations expanding their range, as are wolf populations in many states).

Response of small mammal populations to fuel treatment and precipitation in a ponderosa pine forest, New Mexico

Science.gov (United States)

Karen E. Bagne; Deborah M. Finch

2009-01-01

Mechanical and fire treatments are commonly used to reduce fuels where land use practices have encouraged accumulation of woody debris and high densities of trees. Treatments focus on restoration of vegetation structure, but will also affect wildlife populations. Small mammal populations were monitored before and after dense tree stands were thinned on 2,800 ha in NM,...

Navigating from the heights of technical rigour to the swampy reality: Lessons from New Zealand in population health outcomes monitoring

Directory of Open Access Journals (Sweden)

John Wren

2008-06-01

Full Text Available

Background: The objective of this paper is to describe and discuss two documents produced by the New Zealand Ministry of Health concerning the monitoring of outcomes of public health programs. The New Zealand Government is increasingly expecting planners and managers of publicly funded services to shift their focus from the delivery of ‘outputs’ towards achievement of ‘outcomes’. Intervention logic models and outcomes monitoring are promoted by central government agencies as suitable management methods for implementing the change. [1-3]

Methods: To help managers design and implement comprehensive, effective and measurable population health programmes the Ministry of Health recently published two guidance documents. The first document provided guidance about how to plan programmes using a generic logic model approach.[4] The second set out in detail a process on how to monitor population health programmes.[5] The intent of the documents was to help managers navigate between the heights of technical rigour and the swamps of reality in the delivery of population health programmes.[6]

Results: A number of issues and implications for how population health programmes are planned monitored and performance assessed have been identified by the guidance documents. Issues include the problem of small numbers, understanding the difference between outcomes monitoring and traditional forms of evaluation, and outcomes monitoring being seen as a tool for punitive performance management rather than ‘continuous programme improvement’. Implications include more time spent on the design of programmes. Planners will need to focus upon better sequencing of activities, setting more specific and time limited goals, and to be more informed about how to use research to inform the selection of interventions.

Conclusions: The guidance documents promoted by

Public support for river restoration funding in relation to local river ecomorphology, population density, and mean income

Science.gov (United States)

SchläPfer, Felix; Witzig, Pieter-Jan

2006-12-01

In 1997, about 140,000 citizens in 388 voting districts in the Swiss canton of Bern passed a ballot initiative to allocate about 3 million Swiss Francs annually to a canton-wide river restoration program. Using the municipal voting returns and a detailed georeferenced data set on the ecomorphological status of the rivers, we estimate models of voter support in relation to local river ecomorphology, population density, mean income, cultural background, and recent flood damage. Support of the initiative increased with increasing population density and tended to increase with increasing mean income, in spite of progressive taxation. Furthermore, we found evidence that public support increased with decreasing "naturalness" of local rivers. The model estimates may be cautiously used to predict the public acceptance of similar restoration programs in comparable regions. Moreover, the voting-based insights into the distribution of river restoration benefits provide a useful starting point for debates about appropriate financing schemes.

Effects of population density on growth and production of Tilapia in monoculture

Directory of Open Access Journals (Sweden)

TH Majumder

2017-12-01

Full Text Available The experiment was conducted to determine the effect of population density on growth and production of Tilapia (monosex GIFT tilapia in monoculture system for a period of 110 days. The experiment was carried out in six earthen ponds, which were situated in the Bangladesh Agricultural University Campus, Mymensingh. The experiment was carried out under three treatments each with two replications. Fish population density was 200 fish per decimal under treatment-I, 400 fish per decimal under treatment-II and 600 fish per decimal under treatment-III. In the ponds supplementary feed of wheat bran and rice bran mixture were used daily at the rate of 46 g, 92 g and 136 g per decimal under treatment-I, II, and III, respectively. The average initial length and weight of tilapia were 4.63 cm and 2.82 g respectively. The ponds were fertilized fortnightly with urea and TSP at the rates of 60 g and 90 g, respectively. During experimental period, the ranges of water temperature (25.82 to 29.80 ºC, transparency (28.00 to 38.00 cm, dissolved oxygen (5.50 to 8.30 mg/L, pH (7.00 to 7.90, total alkalinity (130.00 to 200.00 mg/L, free CO2 (2.00 to 6.00 mg/L, phosphate-phosphorus (1.20 to 2.30 mg/L, and nitrate-nitrogen (3.20 to 4.00 mg/L were within the productive range and more or less similar in all the ponds under three treatments. There were 25 genera of phytoplankton under five major groups and 10 genera of zooplankton under three major groups in the experimental ponds. Mean survival rate of fish under treatment-I, treatment-II, and treatment-III were 82.75%, 77.12% and 74.33% respectively. The calculated net fish production under treatment-I was 6.75 ton/ha/yr and that of the ponds under treatment-II was 10.26 ton/ha/yr and that of the ponds under treatment-III was 12.15 ton/ha/yr. The net fish production under treatment-II and treatment-III were 152% and 180% higher than that of treatment-I, taking net fish production under treatment-I for 100%. According to

Influence of inoculum density on population dynamics and dauer juvenile yields in liquid culture of biocontrol nematodes Steinernema carpocapsae and S. feltiae (Nematoda: Rhabditida).

Science.gov (United States)

Hirao, Ayako; Ehlers, Ralf-Udo

2010-01-01

For improvement of mass production of the rhabditid biocontrol nematodes Steinernema carpocapsae and Steinernema feltiae in monoxenic liquid culture with their bacterial symbionts Xenorhabdus nematophila and Xenorhabdus bovienii, respectively, the effect of the initial nematode inoculum density on population development and final concentration of dauer juveniles (DJs) was investigated. Symbiotic bacterial cultures are pre-incubated for 1 day prior to inoculation of DJs. DJs are developmentally arrested and recover development as a reaction to food signals provided by their symbionts. After development to adults, the nematodes produce DJ offspring. Inoculum density ranged from 1 to 10 x 10(3) DJ per milliliter for S. carpocapsae and 1 to 8 x 10(3) DJs per milliliter for S. feltiae. No significant influence of the inoculum density on the final DJ yields in both nematode species was recorded, except for S. carpocapsae cultures with a parental female density 300 for S. carpocapsae and almost 200 for S. feltiae. The compensative adaptation of fecundity to nematode population density is responsible for the lack of an inoculum (or parental female) density effect on DJ yields. At optimal inoculation density of S. carpocapsae, offspring were produced by the parental female population, whereas S. feltiae always developed a F1 female population, which contributed to the DJ yields and was the reason for a more scattered distribution of the yields. The F1 female generation was accompanied by a second peak in X. bovienii density. The optimal DJ inoculum density for S. carpocapsae is 3-6 x 10(3) DJs per milliliter in order to obtain >10(3) parental females per milliliter. Density-dependent effects were neither observed on the DJ recovery nor on the sex ratio in the parental adult generation. As recovery varied between different batches, assessment of the recovery of inoculum DJ batches is recommended. S. feltiae was less variable in DJ recovery usually reaching >90%. The

Paternal epigenetic effects of population density on locust phase-related characteristics associated with heat-shock protein expression.

Science.gov (United States)

Chen, Bing; Li, Shaoqin; Ren, Qiang; Tong, Xiwen; Zhang, Xia; Kang, Le

2015-02-01

Many species exhibit transgenerational plasticity by which environmental cues experienced by either parent can be transmitted to their offspring, resulting in phenotypic variants in offspring to match ancestral environments. However, the manner by which paternal experiences affect offspring plasticity through epigenetic inheritance in animals generally remains unclear. In this study, we examined the transgenerational effects of population density on phase-related traits in the migratory locust Locusta migratoria. Using an experimental design that explicitly controls genetic background, we found that the effects of crowd or isolation rearing on phase plasticity could be inherited to the offspring. The isolation of gregarious locusts resulted in reduced weight in offspring eggs and altered morphometric traits in hatchlings, whereas crowding of solitarious locusts exhibited opposite effects. The consequences of density changes were transmitted by both maternal and paternal inheritance, although the expression of paternal effects was not as pronounced as that of maternal effects. Prominent expression of heat-shock proteins (Hsps), such as Hsp90, Hsp70 and Hsp20.6, could be triggered by density changes. Hsps were significantly upregulated upon crowding but downregulated upon isolation. The variation in parental Hsp expression was also transmitted to the offspring, in which the pattern of inheritance was consistent with that of phase characteristics. These results revealed a paternal effect on phase polyphenism and Hsp expression induced by population density, and defined a model system that could be used to study the paternal epigenetic inheritance of environmental changes. © 2015 John Wiley & Sons Ltd.

Ecological monitoring in a discrete-time prey-predator model.

Science.gov (United States)

Gámez, M; López, I; Rodríguez, C; Varga, Z; Garay, J

2017-09-21

The paper is aimed at the methodological development of ecological monitoring in discrete-time dynamic models. In earlier papers, in the framework of continuous-time models, we have shown how a systems-theoretical methodology can be applied to the monitoring of the state process of a system of interacting populations, also estimating certain abiotic environmental changes such as pollution, climatic or seasonal changes. In practice, however, there may be good reasons to use discrete-time models. (For instance, there may be discrete cycles in the development of the populations, or observations can be made only at discrete time steps.) Therefore the present paper is devoted to the development of the monitoring methodology in the framework of discrete-time models of population ecology. By monitoring we mean that, observing only certain component(s) of the system, we reconstruct the whole state process. This may be necessary, e.g., when in a complex ecosystem the observation of the densities of certain species is impossible, or too expensive. For the first presentation of the offered methodology, we have chosen a discrete-time version of the classical Lotka-Volterra prey-predator model. This is a minimal but not trivial system where the methodology can still be presented. We also show how this methodology can be applied to estimate the effect of an abiotic environmental change, using a component of the population system as an environmental indicator. Although this approach is illustrated in a simplest possible case, it can be easily extended to larger ecosystems with several interacting populations and different types of abiotic environmental effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sustainable monitoring of roe deer in public hunting areas in the Spanish Pyrenes

Energy Technology Data Exchange (ETDEWEB)

Herrero, J.; Torres, R. T.; Prada, C.; Garcia-Serrano, A.; Gimenez-Anaya, A.; Fernandez, O.

2013-07-01

Aim of study: Monitoring trends in animal populations is essential for the development of appropriate wildlife management strategies. Area of study: The area is situated in the southern Pyrenees (Aragon), Spain. Material and methods: To measure the abundance, population trends, sex ratio, and mortality of roe deer populations, we analyzed data from i) driven hunts for wild boar (hunting seasons 1995/96-2009/10, n = 1,417, ii) itineraries, which were used to calculate the KAI and density using DS (2003-2010, n = 310 itineraries), iii) roe deer carcass recoveries (2006-2010, n = 100), and iv) data from the deer hunting quota fulfillment (2006-2010, n = 325 hunted animals. Main results: Based on DS, in 2010, the average density of roe deer populations was 2.3 km–2 (CV 17%). Based on the KAI and the battues, the estimated average annual rate of increase was 5.8% and 4.3%, respectively. Based on the KAI and the carcass recoveries, the estimates of the population sex ratio were 0.75 (n = 641) and 0.9 (n = 100) males per female, respectively. Carcass recoveries indicated that mortality was highest in late winter and early spring. The average body masses and sizes of males and females were within the ranges reported for other Iberian and European populations. Research highlights: Monitoring should be continued in the Aragon population of roe deer, although larger sample sizes are required to increase the accuracy of estimates and assessments of the impact of management actions. (Author)

Dealing with incomplete and variable detectability in multi-year, multi-site monitoring of ecological populations

Science.gov (United States)

Converse, Sarah J.; Royle, J. Andrew; Gitzen, Robert A.; Millspaugh, Joshua J.; Cooper, Andrew B.; Licht, Daniel S.

2012-01-01

An ecological monitoring program should be viewed as a component of a larger framework designed to advance science and/or management, rather than as a stand-alone activity. Monitoring targets (the ecological variables of interest; e.g. abundance or occurrence of a species) should be set based on the needs of that framework (Nichols and Williams 2006; e.g. Chapters 2–4). Once such monitoring targets are set, the subsequent step in monitoring design involves consideration of the field and analytical methods that will be used to measure monitoring targets with adequate accuracy and precision. Long-term monitoring programs will involve replication of measurements over time, and possibly over space; that is, one location or each of multiple locations will be monitored multiple times, producing a collection of site visits (replicates). Clearly this replication is important for addressing spatial and temporal variability in the ecological resources of interest (Chapters 7–10), but it is worth considering how this replication can further be exploited to increase the effectiveness of monitoring. In particular, defensible monitoring of the majority of animal, and to a lesser degree plant, populations and communities will generally require investigators to account for imperfect detection (Chapters 4, 18). Raw indices of population state variables, such as abundance or occupancy (sensu MacKenzie et al. 2002), are rarely defensible when detection probabilities are failing to correct for differences in detection, resulting in indices that have an unknown relationship to the parameters of interest (e.g. Nichols 1992, Anderson 2001, MacKenzie et al. 2002, Williams et al. 2002, Anderson 2003, White 2005, Kéry and Schmidt 2008). While others have argued that indices may be preferable in some cases due to the challenges associated with estimating detection probabilities (e.g. McKelvey and Pearson 2001, Johnson 2008), we do not attempt to resolve this debate here. Rather, we are

Effects of nano-void density, size and spatial population on thermal conductivity: a case study of GaN crystal

International Nuclear Information System (INIS)

Zhou, X W; Jones, R E

2012-01-01

The thermal conductivity of a crystal is sensitive to the presence of surfaces and nanoscale defects. While this opens tremendous opportunities to tailor thermal conductivity, true ‘phonon engineering’ of nanocrystals for a specific electronic or thermoelectric application can only be achieved when the dependence of thermal conductivity on the defect density, size and spatial population is understood and quantified. Unfortunately, experimental studies of the effects of nanoscale defects are quite challenging. While molecular dynamics simulations are effective in calculating thermal conductivity, the defect density range that can be explored with feasible computing resources is unrealistically high. As a result, previous work has not generated a fully detailed understanding of the dependence of thermal conductivity on nanoscale defects. Using GaN as an example, we have combined a physically motivated analytical model and highly converged large-scale molecular dynamics simulations to study the effects of defects on thermal conductivity. An analytical expression for thermal conductivity as a function of void density, size, and population has been derived and corroborated with the model, simulations, and experiments. (paper)

A first estimate of the structure and density of the populations of pet cats and dogs across Great Britain.

Science.gov (United States)

Aegerter, James; Fouracre, David; Smith, Graham C

2017-01-01

Policy development, implementation, and effective contingency response rely on a strong evidence base to ensure success and cost-effectiveness. Where this includes preventing the establishment or spread of zoonotic or veterinary diseases infecting companion cats and dogs, descriptions of the structure and density of the populations of these pets are useful. Similarly, such descriptions may help in supporting diverse fields of study such as; evidence-based veterinary practice, veterinary epidemiology, public health and ecology. As well as maps of where pets are, estimates of how many may rarely, or never, be seen by veterinarians and might not be appropriately managed in the event of a disease outbreak are also important. Unfortunately both sources of evidence are absent from the scientific and regulatory literatures. We make this first estimate of the structure and density of pet populations by using the most recent national population estimates of cats and dogs across Great Britain and subdividing these spatially, and categorically across ownership classes. For the spatial model we used the location and size of veterinary practises across GB to predict the local density of pets, using client travel time to define catchments around practises, and combined this with residential address data to estimate the rate of ownership. For the estimates of pets which may provoke problems in managing a veterinary or zoonotic disease we reviewed the literature and defined a comprehensive suite of ownership classes for cats and dogs, collated estimates of the sub-populations for each ownership class as well as their rates of interaction and produced a coherent scaled description of the structure of the national population. The predicted density of pets varied substantially, with the lowest densities in rural areas, and the highest in the centres of large cities where each species could exceed 2500 animals.km-2. Conversely, the number of pets per household showed the opposite

Evaluation of Quantra Hologic Volumetric Computerized Breast Density Software in Comparison With Manual Interpretation in a Diverse Population.

Science.gov (United States)

Richard-Davis, Gloria; Whittemore, Brianna; Disher, Anthony; Rice, Valerie Montgomery; Lenin, Rathinasamy B; Dollins, Camille; Siegel, Eric R; Eswaran, Hari

2018-01-01

Increased mammographic breast density is a well-established risk factor for breast cancer development, regardless of age or ethnic background. The current gold standard for categorizing breast density consists of a radiologist estimation of percent density according to the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) criteria. This study compares paired qualitative interpretations of breast density on digital mammograms with quantitative measurement of density using Hologic's Food and Drug Administration-approved R2 Quantra volumetric breast density assessment tool. Our goal was to find the best cutoff value of Quantra-calculated breast density for stratifying patients accurately into high-risk and low-risk breast density categories. Screening digital mammograms from 385 subjects, aged 18 to 64 years, were evaluated. These mammograms were interpreted by a radiologist using the ACR's BI-RADS density method, and had quantitative density measured using the R2 Quantra breast density assessment tool. The appropriate cutoff for breast density-based risk stratification using Quantra software was calculated using manually determined BI-RADS scores as a gold standard, in which scores of D3/D4 denoted high-risk densities and D1/D2 denoted low-risk densities. The best cutoff value for risk stratification using Quantra-calculated breast density was found to be 14.0%, yielding a sensitivity of 65%, specificity of 77%, and positive and negative predictive values of 75% and 69%, respectively. Under bootstrap analysis, the best cutoff value had a mean ± SD of 13.70% ± 0.89%. Our study is the first to publish on a North American population that assesses the accuracy of the R2 Quantra system at breast density stratification. Quantitative breast density measures will improve accuracy and reliability of density determination, assisting future researchers to accurately calculate breast cancer risks associated with density increase.

Monitoring population status of sea otters (Enhydra lutris) in Glacier Bay National Park and Preserve, Alaska: options and considerations

Science.gov (United States)

Esslinger, George G.; Esler, Daniel N.; Howlin, S.; Starcevich, L.A.

2015-06-25

After many decades of absence from southeast Alaska, sea otters (Enhydra lutris) are recolonizing parts of their former range, including Glacier Bay, Alaska. Sea otters are well known for structuring nearshore ecosystems and causing community-level changes such as increases in kelp abundance and changes in the size and number of other consumers. Monitoring population status of sea otters in Glacier Bay will help park researchers and managers understand and interpret sea otter-induced ecosystem changes relative to other sources of variation, including potential human-induced impacts such as ocean acidification, vessel disturbance, and oil spills. This report was prepared for the National Park Service (NPS), Southeast Alaska Inventory and Monitoring Network following a request for evaluation of options for monitoring sea otter population status in Glacier Bay National Park and Preserve. To meet this request, we provide a detailed consideration of the primary method of assessment of abundance and distribution, aerial surveys, including analyses of power to detect interannual trends and designs to reduce variation around annual abundance estimates. We also describe two alternate techniques for evaluating sea otter population status—(1) quantifying sea otter diets and energy intake rates, and (2) detecting change in ages at death. In addition, we provide a brief section on directed research to identify studies that would further our understanding of sea otter population dynamics and effects on the Glacier Bay ecosystem, and provide context for interpreting results of monitoring activities.

Diallel analyze of yield and progress of the severity of leaf diseases in maize hybrids in two population density

Directory of Open Access Journals (Sweden)

Marcos Ventura Faria

2015-02-01

Full Text Available Seven commercial maize hybrids (AS1575, 2B688, Penta, GNZ2004, AG8021, Sprint e P30F53 were intercrossed in a complete diallel, excluded reciprocal, obtaining 21 crosses. The 28 treatments were evaluated in two environments characterized by different densities (62,500 and 90,000 plants ha-1, with the aim of selecting the most promising parents for generating base population to obtain lines. Two experiments were carried out in Guarapuava-PR, at randomized block design with three replications. We estimated the general (GCA and specific (SCA combining abilities for yield and disease severity assessed by the area under the common rust (Puccinia sorghi progress curve (AURPC and the area under the leaf spot (Cercospora zeae-maydis progress curve (AULPC. The effects of GCA and SCA were significant for grain yield and diseases severity in both densities, revealing the importance of both additive and non-additive effects. There GCA x densities interaction was significant only for grain yield. Crossings P30F53 x AG8021 and P30F53 x Penta had negative estimates of SCA for AURPC and AULPC on the environments average. Hybrids GNZ 2004 and P30F53 stood out showing positive GCA for grain yield and negative for AURPC and AULPC in both densities and therefore are recommended for generating base populations for obtaining lines adapted for both densities, conventional and denser plantings, given the current trends in management of maize.

Estimating the population size and colony boundary of subterranean termites by using the density functions of directionally averaged capture probability.

Science.gov (United States)

Su, Nan-Yao; Lee, Sang-Hee

2008-04-01

Marked termites were released in a linear-connected foraging arena, and the spatial heterogeneity of their capture probabilities was averaged for both directions at distance r from release point to obtain a symmetrical distribution, from which the density function of directionally averaged capture probability P(x) was derived. We hypothesized that as marked termites move into the population and given sufficient time, the directionally averaged capture probability may reach an equilibrium P(e) over the distance r and thus satisfy the equal mixing assumption of the mark-recapture protocol. The equilibrium capture probability P(e) was used to estimate the population size N. The hypothesis was tested in a 50-m extended foraging arena to simulate the distance factor of field colonies of subterranean termites. Over the 42-d test period, the density functions of directionally averaged capture probability P(x) exhibited four phases: exponential decline phase, linear decline phase, equilibrium phase, and postequilibrium phase. The equilibrium capture probability P(e), derived as the intercept of the linear regression during the equilibrium phase, correctly projected N estimates that were not significantly different from the known number of workers in the arena. Because the area beneath the probability density function is a constant (50% in this study), preequilibrium regression parameters and P(e) were used to estimate the population boundary distance 1, which is the distance between the release point and the boundary beyond which the population is absent.

Stone crayfish in the Czech Republic: how does its population density depend on basic chemical and physical properties of water?

Directory of Open Access Journals (Sweden)

Vlach P.

2013-03-01

Full Text Available The stone crayfish (Austropotamobius torrentium Schrank is one of the two native crayfish species in the Czech Republic. The populations as well as physical and chemical parameters of water (pH, conductivity, dissolved oxygen, undissolved particles, NH3, NH4+, NO2−, NO3−, phosphorus, Ca2+ and SO42 −  of 33 streams were examined to find the ecological plasticity of this crayfish and some relations between these parameters and population densities. The mentioned parameters often significantly varied at the sites. Two approaches were applied to find relations between these parameters and observed abundance. At first, the observed streams were compared using RDA (streams  ×  physical-chemical parameters. No significance was found while testing relationship between the streams grouped along the 1st axis of model and the observed abundances of stone crayfish. However, some correlations between abundance and conductivity, calcium, nitrates and sulphates were found using polynomial regression. These relationships are explicable in terms of mutual correlations, underlying geology and other factors which affect abundances. In conclusion, A. torrentium is able to inhabit waters with a large range of physical and chemical parameters of the water without any fundamental influence on population densities. Water properties play an indisputable role as limiting ecological factors at uncommon concentrations, but population densities are probably influenced much more by the types of habitats, habitat features, predation and other ecological factors.

Anomalous evolution of Ar metastable density with electron density in high density Ar discharge

International Nuclear Information System (INIS)

Park, Min; Chang, Hong-Young; You, Shin-Jae; Kim, Jung-Hyung; Shin, Yong-Hyeon

2011-01-01

Recently, an anomalous evolution of argon metastable density with plasma discharge power (electron density) was reported [A. M. Daltrini, S. A. Moshkalev, T. J. Morgan, R. B. Piejak, and W. G. Graham, Appl. Phys. Lett. 92, 061504 (2008)]. Although the importance of the metastable atom and its density has been reported in a lot of literature, however, a basic physics behind the anomalous evolution of metastable density has not been clearly understood yet. In this study, we investigated a simple global model to elucidate the underlying physics of the anomalous evolution of argon metastable density with the electron density. On the basis of the proposed simple model, we reproduced the anomalous evolution of the metastable density and disclosed the detailed physics for the anomalous result. Drastic changes of dominant mechanisms for the population and depopulation processes of Ar metastable atoms with electron density, which take place even in relatively low electron density regime, is the clue to understand the result.

Health and safety impacts of nuclear, geothermal, and fossil-fuel electric generation in California. Volume 5. Control of population densities surrounding nuclear power plants

International Nuclear Information System (INIS)

Nero, A.V.; Schroeder, C.H.; Yen, W.W.S.

1977-01-01

In view of the requirement that the California Energy Resources Conservation and Development Commission must specify land-use/population-density control measures to be used in the vicinity of nuclear power plants being granted land use, the possible forms of such measures are examined. Since these measures must maintain population densities below Nuclear Regulatory Commission criteria, if appropriate, NRC criteria for land use and population densities are given particular attention. In addition, a preliminary comparison of the cost of possible control measures with the reduced potential for damage to the public health and safety is made, yielding the result that control measures within approximately one mile of the plant site may be justified, in certain cases, on a strictly cost-benefit basis. However, it is not clear whether controls over such a limited region would satisfy the legal mandate

Developing population models with data from marked individuals

Science.gov (United States)

Hae Yeong Ryu,; Kevin T. Shoemaker,; Eva Kneip,; Anna Pidgeon,; Patricia Heglund,; Brooke Bateman,; Thogmartin, Wayne E.; Reşit Akçakaya,

2016-01-01

Population viability analysis (PVA) is a powerful tool for biodiversity assessments, but its use has been limited because of the requirements for fully specified population models such as demographic structure, density-dependence, environmental stochasticity, and specification of uncertainties. Developing a fully specified population model from commonly available data sources – notably, mark–recapture studies – remains complicated due to lack of practical methods for estimating fecundity, true survival (as opposed to apparent survival), natural temporal variability in both survival and fecundity, density-dependence in the demographic parameters, and uncertainty in model parameters. We present a general method that estimates all the key parameters required to specify a stochastic, matrix-based population model, constructed using a long-term mark–recapture dataset. Unlike standard mark–recapture analyses, our approach provides estimates of true survival rates and fecundities, their respective natural temporal variabilities, and density-dependence functions, making it possible to construct a population model for long-term projection of population dynamics. Furthermore, our method includes a formal quantification of parameter uncertainty for global (multivariate) sensitivity analysis. We apply this approach to 9 bird species and demonstrate the feasibility of using data from the Monitoring Avian Productivity and Survivorship (MAPS) program. Bias-correction factors for raw estimates of survival and fecundity derived from mark–recapture data (apparent survival and juvenile:adult ratio, respectively) were non-negligible, and corrected parameters were generally more biologically reasonable than their uncorrected counterparts. Our method allows the development of fully specified stochastic population models using a single, widely available data source, substantially reducing the barriers that have until now limited the widespread application of PVA. This method

What makes a species common? No evidence of density-dependent recruitment or mortality of the sea urchin Diadema antillarum after the 1983-1984 mass mortality.

Science.gov (United States)

Levitan, Don R; Edmunds, Peter J; Levitan, Keeha E

2014-05-01

A potential consequence of individuals compensating for density-dependent processes is that rare or infrequent events can produce profound and long-term shifts in species abundance. In 1983-1984 a mass mortality event reduced the numbers of the abundant sea urchin Diadema antillarum by 95-99% throughout the Caribbean and western Atlantic. Following this event, the abundance of macroalgae increased and the few surviving D. antillarum responded by increasing in body size and fecundity. These initial observations suggested that populations of D. antillarum could recover rapidly following release from food limitation. In contrast, published studies of field manipulations indicate that this species had traits making it resistant to density-dependent effects on offspring production and adult mortality; this evidence raises the possibility that density-independent processes might keep populations at a diminished level. Decadal-scale (1983-2011) monitoring of recruitment, mortality, population density and size structure of D. antillarum from St John, US Virgin Islands, indicates that population density has remained relatively stable and more than an order of magnitude lower than that before the mortality event of 1983-1984. We detected no evidence of density-dependent mortality or recruitment since this mortality event. In this location, model estimates of equilibrium population density, assuming density-independent processes and based on parameters generated over the first decade following the mortality event, accurately predict the low population density 20 years later (2011). We find no evidence to support the notion that this historically dominant species will rebound from this temporally brief, but spatially widespread, perturbation.

Influence of power density and primer application on polymerization of dual-cured resin cements monitored by ultrasonic measurement.

Science.gov (United States)

Takubo, Chikako; Yasuda, Genta; Murayama, Ryosuke; Ogura, Yukari; Tonegawa, Motoka; Kurokawa, Hiroyasu; Miyazaki, Masashi

2010-08-01

We used ultrasonic measurements to monitor the influence of power density and primer application on the polymerization reaction of dual-cured resin cements. The ultrasonic equipment comprised a pulser-receiver, transducers, and an oscilloscope. Resin cements were mixed and inserted into a transparent mould, and specimens were placed on the sample stage, onto which the primer, if used, was also applied. Power densities of 0 (no irradiation), 200, or 600 mW cm(-2) were used for curing. The transit time through the cement disk was divided by the specimen thickness to obtain the longitudinal sound velocity. When resin cements were light-irradiated, each curve displayed an initial plateau of approximately 1,500 m s(-1), which rapidly increased to a second plateau of 2,300-2,900 m s(-1). The rate of sound velocity increase was retarded when the cements were light-irradiated at lower power densities, and increased when the primer was applied. The polymerization behaviour of dual-cured resin cements was therefore shown to be affected by the power density of the curing unit and the application of self-etching primer. (c) 2010 The Authors. Journal compilation (c) 2010 Eur J Oral Sci.

Ideotype population exploration: growth, photosynthesis, and yield components at different planting densities in winter oilseed rape (Brassica napus L.).

Science.gov (United States)

Ma, Ni; Yuan, Jinzhan; Li, Ming; Li, Jun; Zhang, Liyan; Liu, Lixin; Naeem, Muhammad Shahbaz; Zhang, Chunlei

2014-01-01

Rapeseed is one of the most important edible oil crops in the world and the seed yield has lagged behind the increasing demand driven by population growth. Winter oilseed rape (Brassica napus L.) is widely cultivated with relatively low yield in China, so it is necessary to find the strategies to improve the expression of yield potential. Planting density has great effects on seed yield of crops. Hence, field experiments were conducted in Wuhan in the Yangtze River basin with one conventional variety (Zhongshuang 11, ZS11) and one hybrid variety (Huayouza 9, HYZ9) at five planting densities (27.0×10(4), 37.5×10(4), 48.0×10(4), 58.5×10(4), 69.0×10(4) plants ha(-1)) during 2010-2012 to investigate the yield components. The physiological traits for high-yield and normal-yield populations were measured during 2011-2013. Our results indicated that planting densities of 58.5×10(4) plants ha(-1) in ZS11 and 48.0×10(4) plants ha(-1) in HYZ9 have significantly higher yield compared with the density of 27.0×10(4) plants ha(-1) for both varieties. The ideal silique numbers for ZS11 and HYZ9 were ∼0.9×10(4) (n m(-2)) and ∼1×10(4) (n m(-2)), respectively, and ideal primary branches for ZS11 and HYZ9 were ∼250 (n m(-2)) and ∼300 (n m(-2)), respectively. The highest leaf area index (LAI) and silique wall area index (SAI) was ∼5.0 and 7.0, respectively. Moreover, higher leaf net photosynthetic rate (Pn) and water use efficiency (WUE) were observed in the high-yield populations. A significantly higher level of silique wall photosynthesis and rapid dry matter accumulation were supposed to result in the maximum seed yield. Our results suggest that increasing the planting density within certain range is a feasible approach for higher seed yield in winter rapeseed in China.

The population density of Lymnaea columella (Say, 1817) (Mollusca, Lymnaeidae) an intermediate host of Fasciola hepatica (Linnaeus, 1758), in the Caparaó microregion, ES, Brazil.

Science.gov (United States)

D'Almeida, S C G; Freitas, D F; Carneiro, M B; Camargo, P F; Azevedo, J C; Martins, I V F

2016-06-01

The aim of this study was to monitor the population density of Lymnaea columella, an intermediate host of Fasciola hepatica, in various aquatic habitats and in drinking water in the area of the Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo, on Caparaó Microregion, municipality of Alegre, state of Espírito Santo, Brazil. Monthly samplings were performed at certain points between drainage areas and drinking water in cattle and goat production systems during the years 2010 to 2013. The mean temperature, precipitation and the frequency of samples of L. columella were analysed graphically according the monthly average during the study period. A total of 2,038 molluscs were collected, 1558 of which were L. columella, that predominated in all sampled points. The highest average of specimens observed for L. columella was in the years 2010 and 2013 (51.0), and occurred decreased in 2011 (19.8). The temperature and precipitation averaged is 23.7 °C and 141 mm/year, respectively. Rainfall peak occurred in March (2011, 2013) and November (2012), during these periods the population of L. columella growth. There was no significant difference in the relationship between the specimens observed with seasons (dry-wet), thus the population of L. columella remained stable and can be found throughout the year.

Genetic spectrum of low density lipoprotein receptor gene variations in South Indian population.

Science.gov (United States)

ArulJothi, K N; Suruthi Abirami, B; Devi, Arikketh

2018-03-01

Low density lipoprotein receptor (LDLR) is a membrane bound receptor maintaining cholesterol homeostasis along with Apolipoprotein B (APOB), Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) and other genes of lipid metabolism. Any pathogenic variation in these genes alters the function of the receptor and leads to Familial Hypercholesterolemia (FH) and other cardiovascular diseases. This study was aimed at screening the LDLR, APOB and PCSK9 genes in Hypercholesterolemic patients to define the genetic spectrum of FH in Indian population. Familial Hypercholesterolemia patients (n=78) of South Indian Tamil population with LDL cholesterol and Total cholesterol levels above 4.9mmol/l and 7.5mmol/l with family history of Myocardial infarction were involved. DNA was isolated by organic extraction method from blood samples and LDLR, APOB and PCSK9 gene exons were amplified using primers that cover exon-intron boundaries. The amplicons were screened using High Resolution Melt (HRM) Analysis and the screened samples were sequenced after purification. This study reports 20 variations in South Indian population for the first time. In this set of variations 9 are novel variations which are reported for the first time, 11 were reported in other studies also. The in silico analysis for all the variations detected in this study were done to predict the probabilistic effect in pathogenicity of FH. This study adds 9 novel variations and 11 recurrent variations to the spectrum of LDLR gene mutations in Indian population. All these variations are reported for the first time in Indian population. This spectrum of variations was different from the variations of previous Indian reports. Copyright © 2017 Elsevier B.V. All rights reserved.

Monitoring the establishment and prevalence of the fungal entomopathogen Entomophaga maimaiga in two Lymantria dispar L. populations in Bulgaria

Science.gov (United States)

D. Pilarska; M. McManus; P. Pilarska; G. Georgiev; P. Mirchev; A. Linde

2005-01-01

The establishment and prevalence of the entomopathogenic fungus Entomophaga maimaiga, (Zygomycetes, Entomophthorales), introduced into two gypsy moth populations in Bulgaria, was monitored during 2000-2004. In the Karlovo Region population, where E. maimaiga was introduced in 1999, the fungus was recovered every year and the...

SINUPERM N: a new digital neutron flux density monitoring system

International Nuclear Information System (INIS)

Flick, H.A.

1993-01-01

The new SINUPERM N System is developed for Neutron Monitoring in nuclear power plants. The development was started in 1989 (with the design specification) and will be finished in 1993 (with the qualification). The first built will be the nuclear power plant in Borselle (Netherlands). The design is based on a microprocessor system with a digital signal processor for calculations and signal filtering. The separation between analogue-input signals and digital processing enables for each detector type special input modules and standard output interfaces e.g. field - bus. The wide range of the Neutron Flux Density from 10 -2 cm -2 s -1 up to 10 8 cm -2 s -1 for the out-of-pile instrumentation and up to 10 14 cm -2 s -1 for the in-core-instrumentation will be covered by the SINUPERM N system. The requirements to be met by the SINUPERM N system are the IEEE 323, IEC 987 and the German standard KTA-3503 for safety systems. Other standards for instrumentation and control systems like IEC 801, IEC 1131 and IEC 68 for EMV, climatic and seismic requirements are also included in the hardware type test. The software requirement depends on the IEC 880 standard. (author). 3 figs

Potential misuse of avian density as a conservation metric

Science.gov (United States)

Skagen, Susan K.; Yackel Adams, Amy A.

2011-01-01

Effective conservation metrics are needed to evaluate the success of management in a rapidly changing world. Reproductive rates and densities of breeding birds (as a surrogate for reproductive rate) have been used to indicate the quality of avian breeding habitat, but the underlying assumptions of these metrics rarely have been examined. When birds are attracted to breeding areas in part by the presence of conspecifics and when breeding in groups influences predation rates, the effectiveness of density and reproductive rate as indicators of habitat quality is reduced. It is beneficial to clearly distinguish between individual- and population-level processes when evaluating habitat quality. We use the term reproductive rate to refer to both levels and further distinguish among levels by using the terms per capita fecundity (number of female offspring per female per year, individual level) and population growth rate (the product of density and per capita fecundity, population level). We predicted how density and reproductive rate interact over time under density-independent and density-dependent scenarios, assuming the ideal free distribution model of how birds settle in breeding habitats. We predicted population density of small populations would be correlated positively with both per capita fecundity and population growth rate due to the Allee effect. For populations in the density-dependent growth phase, we predicted no relation between density and per capita fecundity (because individuals in all patches will equilibrate to the same success rate) and a positive relation between density and population growth rate. Several ecological theories collectively suggest that positive correlations between density and per capita fecundity would be difficult to detect. We constructed a decision tree to guide interpretation of positive, neutral, nonlinear, and negative relations between density and reproductive rates at individual and population levels. ?? 2010 Society for

Adelie penguin population diet monitoring by analysis of food DNA in scats.

Directory of Open Access Journals (Sweden)

Simon N Jarman

Full Text Available The Adélie penguin is the most important animal currently used for ecosystem monitoring in the Southern Ocean. The diet of this species is generally studied by visual analysis of stomach contents; or ratios of isotopes of carbon and nitrogen incorporated into the penguin from its food. There are significant limitations to the information that can be gained from these methods. We evaluated population diet assessment by analysis of food DNA in scats as an alternative method for ecosystem monitoring with Adélie penguins as an indicator species. Scats were collected at four locations, three phases of the breeding cycle, and in four different years. A novel molecular diet assay and bioinformatics pipeline based on nuclear small subunit ribosomal RNA gene (SSU rDNA sequencing was used to identify prey DNA in 389 scats. Analysis of the twelve population sample sets identified spatial and temporal dietary change in Adélie penguin population diet. Prey diversity was found to be greater than previously thought. Krill, fish, copepods and amphipods were the most important food groups, in general agreement with other Adélie penguin dietary studies based on hard part or stable isotope analysis. However, our DNA analysis estimated that a substantial portion of the diet was gelatinous groups such as jellyfish and comb jellies. A range of other prey not previously identified in the diet of this species were also discovered. The diverse prey identified by this DNA-based scat analysis confirms that the generalist feeding of Adélie penguins makes them a useful indicator species for prey community composition in the coastal zone of the Southern Ocean. Scat collection is a simple and non-invasive field sampling method that allows DNA-based estimation of prey community differences at many temporal and spatial scales and provides significant advantages over alternative diet analysis approaches.

Cellulolytic and Butyrivibrio fibrisolvens bacteria population density, after supplementing fodder diets (Pennisetum clandestinum

Directory of Open Access Journals (Sweden)

Licet Molina G

2015-11-01

Full Text Available Objective. Determine the population density of cellulolytic bacteria, Butyrivibrio fibrisolvens and the concentration of vaccenic acid, by supplementing diets consisting of kikuyu grass (Pennisetum clandestinum Hoechst. Ex Chiov. as base ingredient, together with cassava flour and biomass (effluent from ethanol production in rumen simulator-Rusitec. Materials and methods. Four treatments (T were evaluated, these were composed as: T1/Control 1: 100% kikuyu grass with a total protein intake of 23.9%, T2: a mixture of 70% kikuyu grass, 20% biomass and 10% cassava flour with a total protein intake of 19.4%; T3/Control 2: 100% kikuyu grass, with a 17.8% protein intake and T4: 70% kikuyu grass, 20% biomass and 10% cassava flour with a 15.3% protein intake. One and two-way variance analysis was made and the Pearson correlation coefficient was determined. Results. An increase was observed in the population density of viable cellulolytic bacteria (CFU/ml and B. fibrisolvens statistically significant (p<0.005 with treatment T2, in contrast to T1, T3 and T4 treatments. In addition, there was a significant increase in the concentration of vaccenic acid (mg/L in the ruminal content in Rusitec with the same treatment (T2. Conclusions. Results obtained in this ruminal simulation study are evidence to the benefits of kikuyu grass together with cassava flour and biomass diet implementation on the growth of ruminal cellulolytic and B. fibrisolvens bacteria, as well as on the production of vaccenic acid. The study also suggests the nutritional potential that such supplements could provide to grazing bovine feeding.

Environmental influences on the species diversity, biomass and population density of soft bottom macrofauna in the estuarine system of Goa, west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Harkantra, S.N.; Rodrigues, N.R.

biomass and total population density and to construct the predictive models. The regression explaining the greatest amount of variation (R2) with all the significant parameter coefficients (r) were presented as the best fit based on adjusted R2... and population density at all the sites for the significant (P < .001-0.0001) best multiple linear regression model except for temperature (Table 2). This explained 32-72% of the total variation (Table 2). No significant best regression fit could...

Density dependence and climate effects in Rocky Mountain elk: an application of regression with instrumental variables for population time series with sampling error.

Science.gov (United States)

Creel, Scott; Creel, Michael

2009-11-01

1. Sampling error in annual estimates of population size creates two widely recognized problems for the analysis of population growth. First, if sampling error is mistakenly treated as process error, one obtains inflated estimates of the variation in true population trajectories (Staples, Taper & Dennis 2004). Second, treating sampling error as process error is thought to overestimate the importance of density dependence in population growth (Viljugrein et al. 2005; Dennis et al. 2006). 2. In ecology, state-space models are used to account for sampling error when estimating the effects of density and other variables on population growth (Staples et al. 2004; Dennis et al. 2006). In econometrics, regression with instrumental variables is a well-established method that addresses the problem of correlation between regressors and the error term, but requires fewer assumptions than state-space models (Davidson & MacKinnon 1993; Cameron & Trivedi 2005). 3. We used instrumental variables to account for sampling error and fit a generalized linear model to 472 annual observations of population size for 35 Elk Management Units in Montana, from 1928 to 2004. We compared this model with state-space models fit with the likelihood function of Dennis et al. (2006). We discuss the general advantages and disadvantages of each method. Briefly, regression with instrumental variables is valid with fewer distributional assumptions, but state-space models are more efficient when their distributional assumptions are met. 4. Both methods found that population growth was negatively related to population density and winter snow accumulation. Summer rainfall and wolf (Canis lupus) presence had much weaker effects on elk (Cervus elaphus) dynamics [though limitation by wolves is strong in some elk populations with well-established wolf populations (Creel et al. 2007; Creel & Christianson 2008)]. 5. Coupled with predictions for Montana from global and regional climate models, our results

Effects of population density and chemical environment on the behavior of Escherichia coli in shallow temperature gradients

International Nuclear Information System (INIS)

Demir, Mahmut; Yoney, Anna; Salman, Hanna; Douarche, Carine; Libchaber, Albert

2011-01-01

In shallow temperature gradients, changes in temperature that bacteria experience occur over long time scales. Therefore, slow processes such as adaptation, metabolism, chemical secretion and even gene expression become important. Since these are cellular processes, the cell density is an important parameter that affects the bacteria's response. We find that there are four density regimes with distinct behaviors. At low cell density, bacteria do not cause changes in their chemical environment; however, their response to the temperature gradient is strongly influenced by it. In the intermediate cell-density regime, the consumption of nutrients becomes significant and induces a gradient of nutrients opposing the temperature gradient due to higher consumption rate at the high temperature. This causes the bacteria to drift toward low temperature. In the high cell-density regime, interactions among bacteria due to secretion of an attractant lead to a strong local accumulation of bacteria. This together with the gradient of nutrients, resulted from the differential consumption rate, creates a fast propagating pulse of bacterial density. These observations are a result of classical nonlinear population dynamics. At extremely high cell density, a change in the physiological state of the bacteria is observed. The bacteria, at the individual level, become cold seeking. This appears initially as a result of a change in the methylation level of the two most abundant sensing receptors, Tsr and Tar. It is further enforced at an even higher cell density by a change in the expression level of these receptors. (perspective)

Effects of husbandry parameters on the life-history traits of the apple snail, Marisa cornuarietis: effects of temperature, photoperiod, and population density.

Science.gov (United States)

Aufderheide, John; Warbritton, Ryan; Pounds, Nadine; File-Emperador, Sharon; Staples, Charles; Caspers, Norbert; Forbes, Valery

2006-04-01

These experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the apple snail, Marisa cornuarietis. The overall objective of the program is to identify suitable husbandry conditions for maintaining multi-generation populations of this species in the laboratory for use in ecotoxicological testing. In this article, we focus on the effects of photoperiod, temperature, and population density on adult fecundity and juvenile growth. Increasing photoperiod from 12 to 16 h of light per day had no effect on adult fecundity or egg hatching and relatively minor effects on juvenile growth and development. Rearing snails at temperatures between 22 degrees C and 28 degrees C did not influence the rates of egg production or egg clutch size. However, the rates of growth and development (of eggs and juveniles) increased with increasing temperature in this range, and when temperatures were reduced to 22 degrees C egg-hatching success was impaired. Juvenile growth and development were more sensitive to rearing density than adult fecundity traits. On the basis of the present results, we conclude that rearing individuals of M. cornuarietis at a temperature of 25 degrees C, a photoperiod of 12L:12D, and a density of <0.8 snails L(-1) (with lower densities for juvenile snails) should provide favorable husbandry conditions for maintaining multi-generation populations of this species.

Sampling Methods for Detection and Monitoring of the Asian Citrus Psyllid (Hemiptera: Psyllidae).

Science.gov (United States)

Monzo, C; Arevalo, H A; Jones, M M; Vanaclocha, P; Croxton, S D; Qureshi, J A; Stansly, P A

2015-06-01

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is a key pest of citrus due to its role as vector of citrus greening disease or "huanglongbing." ACP monitoring is considered an indispensable tool for management of vector and disease. In the present study, datasets collected between 2009 and 2013 from 245 citrus blocks were used to evaluate precision, sensitivity for detection, and efficiency of five sampling methods. The number of samples needed to reach a 0.25 standard error-mean ratio was estimated using Taylor's power law and used to compare precision among sampling methods. Comparison of detection sensitivity and time expenditure (cost) between stem-tap and other sampling methodologies conducted consecutively at the same location were also assessed. Stem-tap sampling was the most efficient sampling method when ACP densities were moderate to high and served as the basis for comparison with all other methods. Protocols that grouped trees near randomly selected locations across the block were more efficient than sampling trees at random across the block. Sweep net sampling was similar to stem-taps in number of captures per sampled unit, but less precise at any ACP density. Yellow sticky traps were 14 times more sensitive than stem-taps but much more time consuming and thus less efficient except at very low population densities. Visual sampling was efficient for detecting and monitoring ACP at low densities. Suction sampling was time consuming and taxing but the most sensitive of all methods for detection of sparse populations. This information can be used to optimize ACP monitoring efforts. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

WSN-Based Space Charge Density Measurement System.

Science.gov (United States)

Deng, Dawei; Yuan, Haiwen; Lv, Jianxun; Ju, Yong

2017-01-01

It is generally acknowledged that high voltage direct current (HVDC) transmission line endures the drawback of large area, because of which the utilization of cable for space charge density monitoring system is of inconvenience. Compared with the traditional communication network, wireless sensor network (WSN) shows advantages in small volume, high flexibility and strong self-organization, thereby presenting great potential in solving the problem. Additionally, WSN is more suitable for the construction of distributed space charge density monitoring system as it has longer distance and higher mobility. A distributed wireless system is designed for collecting and monitoring the space charge density under HVDC transmission lines, which has been widely applied in both Chinese state grid HVDC test base and power transmission projects. Experimental results of the measuring system demonstrated its adaptability in the complex electromagnetic environment under the transmission lines and the ability in realizing accurate, flexible, and stable demands for the measurement of space charge density.

Density Estimation in Several Populations With Uncertain Population Membership

KAUST Repository

Ma, Yanyuan; Hart, Jeffrey D.; Carroll, Raymond J.

2011-01-01

sampled from any given population can be calculated. We develop general estimation procedures and bandwidth selection methods for our setting. We establish large-sample properties and study finite-sample performance using simulation studies. We illustrate

Biannual monitoring of pyrethroid and neonicotinoid susceptibility in Danish pollen beetle (Meligethes aeneus F.) populations

DEFF Research Database (Denmark)

Kaiser, Caroline; Kristensen, Michael; Jensen, Karl-Martin Vagn

2015-01-01

) were used. Pollen beetle populations were collected from 47 locations of Denmark with the help of the consultants and the farmers of the various regions in 2014. Further six populations were tested from Sweden and one from Germany. In the following year 2015, the monitoring continued to find out......The pollen beetle (Meligethes aeneus F.) is a serious pest in the northern countries in oilseed rape. To determine the present level of pyrethroid and neonicotinoid susceptibility of Danish pollen beetle populations, standardized methods recommended by IRAC (Insecticide Resistance Action Committee......, if the resistance level which was determined in 2014 was stable in selected regions. Therefore pollen beetle populations from 14 locations in Denmark and five locations in Germany have been tested. For all tests the standardised methods for pyrethroids, the Adult-vial-test No. 11 and the Adult-vials-test No. 21...

The Distribution and Density of Water Mice (Xeromys myoides in the Maroochy River of Southeast Queensland, Australia.

Directory of Open Access Journals (Sweden)

Janina Kaluza

Full Text Available The water mouse is a small and vulnerable rodent present in coastal areas of south-west Papua New Guinea, and eastern Queensland and the Northern Territory of Australia. Current knowledge regarding the distribution of the water mouse is incomplete and the loss of one local population has been documented in southeast Queensland, a region where pressures from urban and industrial development are increasing. Water mouse populations have not been studied intensively enough to enable the primary factors responsible for the local decline to be identified. We surveyed the distribution and density of the water mouse along the Maroochy River of southeast Queensland, near the southern extent of the species' range, to gather baseline data that may prove valuable for detecting any future decline in this population's size or health. All areas of suitable habitat were surveyed on foot or by kayak or boat over a three-year period. We found 180 water mouse nests, of which ~94% were active. Permanent camera monitoring of one nest and limited supplementary live trapping suggested that up to three individual mice occupied active nests. Water mouse density was estimated to be 0.44 per hectare of suitable habitat along the Maroochy River. Should future monitoring reveal an adverse change in the water mouse population on the Maroochy River, a concerted effort should be made to identify contributing factors and address proximate reasons for the decline.

Consequences of severe habitat fragmentation on density, genetics, and spatial capture-recapture analysis of a small bear population.

Directory of Open Access Journals (Sweden)

Sean M Murphy

Full Text Available Loss and fragmentation of natural habitats caused by human land uses have subdivided several formerly contiguous large carnivore populations into multiple small and often isolated subpopulations, which can reduce genetic variation and lead to precipitous population declines. Substantial habitat loss and fragmentation from urban development and agriculture expansion relegated the Highlands-Glades subpopulation (HGS of Florida, USA, black bears (Ursus americanus floridanus to prolonged isolation; increasing human land development is projected to cause ≥ 50% loss of remaining natural habitats occupied by the HGS in coming decades. We conducted a noninvasive genetic spatial capture-recapture study to quantitatively describe the degree of contemporary habitat fragmentation and investigate the consequences of habitat fragmentation on population density and genetics of the HGS. Remaining natural habitats sustaining the HGS were significantly more fragmented and patchier than those supporting Florida's largest black bear subpopulation. Genetic diversity was low (AR = 3.57; HE = 0.49 and effective population size was small (NE = 25 bears, both of which remained unchanged over a period spanning one bear generation despite evidence of some immigration. Subpopulation density (0.054 bear/km2 was among the lowest reported for black bears, was significantly female-biased, and corresponded to a subpopulation size of 98 bears in available habitat. Conserving remaining natural habitats in the area occupied by the small, genetically depauperate HGS, possibly through conservation easements and government land acquisition, is likely the most important immediate step to ensuring continued persistence of bears in this area. Our study also provides evidence that preferentially placing detectors (e.g., hair traps or cameras primarily in quality habitat across fragmented landscapes poses a challenge to estimating density-habitat covariate relationships using spatial

On the numerical simulation of population dynamics with density-dependent migrations and the Allee effects

International Nuclear Information System (INIS)

Sweilam, H N; Khader, M M; Al-Bar, F R

2008-01-01

In this paper, the variational iteration method (VIM) and the Adomian decomposition method (ADM) are presented for the numerical simulation of the population dynamics model with density-dependent migrations and the Allee effects. The convergence of ADM is proved for the model problem. The results obtained by these methods are compared to the exact solution. It is found that these methods are always converges to the right solutions with high accuracy. Furthermore, VIM needs relative less computational work than ADM

Fluctuations of the population of Daphnia laevis Birge 1878: a six-year study in a tropical lake

Directory of Open Access Journals (Sweden)

LPM. Brandão

Full Text Available The fluctuation of the population of Daphnia laevis in Lake Jacaré (Middle River Doce, Minas Gerais was monitored monthly (at one point in the limnetic region for six years (2002-2007 as part of the Program of Long-Term Ecological Research (LTER/UFMG. The following parameters were also monitored: water temperature, pH, electrical conductivity, dissolved oxygen, chlorophyll a, total phosphorus, phosphate, total nitrogen, nitrate, nitrite, ammonia, and densities of Chaoborus and ephippia of Daphnia laevis in the sediment. A seasonal pattern was observed in the fluctuation of D. laevis, with higher densities recorded during periods of circulation (May-August. A significant correlation was found between the density of D. laevis and temperature (r = -0.47, p = 0.0001, chlorophyll-a (r = -0.32, p = 0.016 and indicators of the lake's trophic status (total phosphorus, r = 0.32, p = 0.007 and trophic state, r = 0.36, p = 0.003, as well as Chaoborus density (r = 0.43 and p = 0.002. These results indicate that changes in the physical and chemical characteristics of the water related with stratification and circulation of the lake may have a direct (temperature, total phosphorous or an indirect (food availability, presence of predators, ephippia eclosion influence on the fluctuation of the D. laevis population.

MONITORING RESISTENSI POPULASI Plutella xylostella, L TERHADAP RESIDU EMAMEKTIN BENZOAT DI SENTRA PRODUKSI TANAMAN KUBIS PROPINSI JAWA TENGAH (Monitoring the Resistance of Plutella xylostella, L Population against Emamektin Benzoate Residues

Directory of Open Access Journals (Sweden)

Udi Tarwotjo

2014-10-01

The objectives of this research to know the susceptible of P. xylostella population against emamectin benzoate insecticide, to monitor the resistance development of  P. xylostella against insecticides by determine of a diagnostic concentration, to determine the resistance mechanism of P. xylostella population. P. xylostella  was collected from central of Java areas from August 2011 up to September 2012.  The data from bioassay test was analized using Probit analysis to obtain LC50 value. The suseptibility test of the insect resulted show that Puasan population (Ngablak FR value was 3.97 and it was higher than  the Selo population (Cepogo. The concentration of 2443.99 ppb as selected diagnostic consentration. The test result of diagnostic concentration validation indicated that the value of calculated c2 of all the tested population was lower than the value of c2table. Therefore the diagnostic concentration of 2443.99 ppb can be used monitoring device of susceptible P, xylostella population. The resistance mechanism of the P. xylostella to the insecticide resulted from the increase in the detoxification rate in the insect body by MFO enzyme, but non-specific esterase enzyme activity did not reflect the esterase activity.

Monitoring of plutonium contaminated solid waste streams. Chapter II: principles and theory of radiometric assay

International Nuclear Information System (INIS)

Birkhoff, G.; Bondar, L.; Notea, A.; Segal, Y.

1977-01-01

The interpretation of a count rate distribution obtained from radiometric assay of a given waste items population in terms of source strength distribution is discussed. A model for the evaluation of errors, arising from non uniform source density distribution (Pu) within the item volume and heterogeneity of matrix materials, is presented. Points concerning calibration procedures and representativity of reference materials are dealt with. Qualification procedures for possible monitoring systems are outlined on the basis of comparison with reference systems. The latter are composed of reference monitors based on high resolution gamma spectrometry and passive and active neutron techniques. The importance of information upon the elemental composition and density distribution of matrix materials for the interpretation of radiometric assay of solid wastes is stressed

Population Growth and Its Expression in Spatial Built-up Patterns: The Sana’a, Yemen Case Study

Directory of Open Access Journals (Sweden)

Gunter Zeug

2010-04-01

Full Text Available In light of rapid global urbanisation, monitoring and mapping of urban and population growth is of great importance. Population growth in Sana’a was investigated for this reason. The capital of the Republic of Yemen is a rapidly growing middle sized city where the population doubles almost every ten years. Satellite data from four different sensors were used to explore urban growth in Sana’a between 1989 and 2007, assisted by topographic maps and cadastral vector data. The analysis was conducted by delineating the built-up areas from the various optical satellite data, applying a fuzzy-rule-based composition of anisotropic textural measures and interactive thresholding. The resulting datasets were used to analyse urban growth and changes in built-up density per district, qualitatively as well as quantitatively, using a geographic information system. The built-up area increased by 87 % between 1989 and 2007. Built-up density has increased in all areas, but particularly in the northern and southern suburban districts, also reflecting the natural barrier of surrounding mountain ranges. Based on long-term population figures, geometric population growth was assumed. This hypothesis was used together with census data for 1994 and 2004 to estimate population figures for 1989 and 2007, resulting in overall growth of about 240%. By joining population figures to district boundaries, the spatial patterns of population distribution and growth were examined. Further, urban built-up growth and population changes over time were brought into relation in order to investigate changes in population density per built-up area. Population densities increased in all districts, with the greatest density change in the peripheral areas towards the North. The results reflect the pressure on the city’s infrastructure and natural resources and could contribute to sustainable urban planning in the city of Sana’a.

A low-density SNP array for analyzing differential selection in freshwater and marine populations of threespine stickleback (Gasterosteus aculeatus).

Science.gov (United States)

Ferchaud, Anne-Laure; Pedersen, Susanne H; Bekkevold, Dorte; Jian, Jianbo; Niu, Yongchao; Hansen, Michael M

2014-10-06

The threespine stickleback (Gasterosteus aculeatus) has become an important model species for studying both contemporary and parallel evolution. In particular, differential adaptation to freshwater and marine environments has led to high differentiation between freshwater and marine stickleback populations at the phenotypic trait of lateral plate morphology and the underlying candidate gene Ectodysplacin (EDA). Many studies have focused on this trait and candidate gene, although other genes involved in marine-freshwater adaptation may be equally important. In order to develop a resource for rapid and cost efficient analysis of genetic divergence between freshwater and marine sticklebacks, we generated a low-density SNP (Single Nucleotide Polymorphism) array encompassing markers of chromosome regions under putative directional selection, along with neutral markers for background. RAD (Restriction site Associated DNA) sequencing of sixty individuals representing two freshwater and one marine population led to the identification of 33,993 SNP markers. Ninety-six of these were chosen for the low-density SNP array, among which 70 represented SNPs under putatively directional selection in freshwater vs. marine environments, whereas 26 SNPs were assumed to be neutral. Annotation of these regions revealed several genes that are candidates for affecting stickleback phenotypic variation, some of which have been observed in previous studies whereas others are new. We have developed a cost-efficient low-density SNP array that allows for rapid screening of polymorphisms in threespine stickleback. The array provides a valuable tool for analyzing adaptive divergence between freshwater and marine stickleback populations beyond the well-established candidate gene Ectodysplacin (EDA).

Hyperthermic survival of Chinese hamster ovary cells as a function of cellular population density at the time of plating

International Nuclear Information System (INIS)

Highfield, D.P.; Holahan, E.V.; Holahan, P.K.; Dewey, W.C.

1984-01-01

The survival of synchronous G 1 or asynchronous Chinese hamster ovary cells in vitro to heat treatment may depend on the cellular population density at the time of heating and/or as the cells are cultured after heating. The addition of lethally irradiated feeder cells may increase survival at 10 -3 by as much as 10- to 100-fold for a variety of conditions when cells are heated either in suspension culture or as monolayers with or without trypsinization. The protective effect associated with feeder cells appears to be associated with close cell-to-cell proximity. However, when cells are heated without trypsinization about 24 hr or later after plating, when adaptation to monolayer has occurred, the protective effect is reduced; i.e., addition of feeder cells enhances survival much less, for example, about 2- to 3-fold at 10 -2 -10 -3 survival. Also, the survival of a cell to heat is independent of whether the neighboring cell in a microcolony is destined to live or die. Finally, if protective effects associated with cell density do occur and are not controlled, serious artifacts can result as the interaction of heat and radiation is studied; for example, survival curves can be moved upward, and thus changed in shape as the number of cells plated is increased with an increase in the hyperthermic treatment or radiation dose following hyperthermia. Therefore, to understand mechanisms and to obtain information relevant to populations of cells in close proximity, such as those in vivo, these cellular population density effects should be considered and understood

Artificially constructed quorum-sensing circuits are used for subtle control of bacterial population density.

Directory of Open Access Journals (Sweden)

Zhaoshou Wang

Full Text Available Vibrio fischeri is a typical quorum-sensing bacterium for which lux box, luxR, and luxI have been identified as the key elements involved in quorum sensing. To decode the quorum-sensing mechanism, an artificially constructed cell-cell communication system has been built. In brief, the system expresses several programmed cell-death BioBricks and quorum-sensing genes driven by the promoters lux pR and PlacO-1 in Escherichia coli cells. Their transformation and expression was confirmed by gel electrophoresis and sequencing. To evaluate its performance, viable cell numbers at various time periods were investigated. Our results showed that bacteria expressing killer proteins corresponding to ribosome binding site efficiency of 0.07, 0.3, 0.6, or 1.0 successfully sensed each other in a population-dependent manner and communicated with each other to subtly control their population density. This was also validated using a proposed simple mathematical model.

Monitoring of arrhythmia and sudden death in a hemodialysis population: The CRASH-ILR Study.

Directory of Open Access Journals (Sweden)

Paul R Roberts

Full Text Available It has been suggested that sudden cardiac death (SCD contributes around 50% of cardiovascular and 27% of all-cause mortality in hemodialysis patients. The true burden of arrhythmias and arrhythmic deaths in this population, however, remains poorly characterised. Cardio Renal Arrhythmia Study in Hemodialysis (CRASH-ILR is a prospective, implantable loop recorder single centre study of 30 established hemodialysis patients and one of the first to provide long-term ambulatory ECG monitoring.30 patients (60% male aged 68±12 years receiving hemodialysis for 45±40 months with varied etiology (diabetes 37%, hypertension 23% and left ventricular ejection fraction (LVEF 55±8% received a Reveal XT implantable loop recorder (Medtronic, USA between August 2011 and October 2014. ECG data from loop recorders were transmitted at each hemodialysis session using a remote monitoring system. Primary outcome was SCD or implantation of a (tachy or bradyarrhythmia controlling device and secondary outcome, the development of arrhythmia necessitating medical intervention.During 379,512 hours of continuous ECG monitoring (mean 12,648±9,024 hours/patient, there were 8 deaths-2 SCD and 6 due to generalised deterioration/sepsis. 5 (20% patients had a primary outcome event (2 SCD, 3 pacemaker implantations for bradyarrhythmia. 10 (33% patients reached an arrhythmic primary or secondary end point. Median event free survival for any arrhythmia was 2.6 years (95% confidence intervals 1.6-3.6 years.The findings confirm the high mortality rate seen in hemodialysis populations and contrary to initial expectations, bradyarrhythmias emerged as a common and potentially significant arrhythmic event.

Effects of subsidized predators, resource variability, and human population density on desert tortoise populations in the Mojave Desert, USA

Science.gov (United States)

Esque, Todd C.; Nussear, Kenneth E.; Drake, K. Kristina; Walde, Andrew D.; Berry, Kristin H.; Averill-Murray, Roy C.; Woodman, A. Peter; Boarman, William I.; Medica, Phil A.; Mack, Jeremy S.; Heaton, Jill S.

2010-01-01

Understanding predator–prey relationships can be pivotal in the conservation of species. For 2 decades, desert tortoise Gopherus agassizii populations have declined, yet quantitative evidence regarding the causes of declines is scarce. In 2005, Ft. Irwin National Training Center, California, USA, implemented a translocation project including 2 yr of baseline monitoring of desert tortoises. Unusually high predation on tortoises was observed after translocation occurred. We conducted a retrospective analysis of predation and found that translocation did not affect the probability of predation: translocated, resident, and control tortoises all had similar levels of predation. However, predation rates were higher near human population concentrations, at lower elevation sites, and for smaller tortoises and females. Furthermore, high mortality rates were not limited to the National Training Center. In 2008, elevated mortality (as high as 43%) occurred throughout the listed range of the desert tortoise. Although no temporal prey base data are available for analysis from any of the study sites, we hypothesize that low population levels of typical coyote Canis latrans prey (i.e. jackrabbits Lepus californicus and other small animals) due to drought conditions influenced high predation rates in previous years. Predation may have been exacerbated in areas with high levels of subsidized predators. Many historical reports of increased predation, and our observation of a range-wide pattern, may indicate that high predation rates are more common than generally considered and may impact recovery of the desert tortoise throughout its range.