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Sample records for honduras population dynamics

  1. Honduras.

    Science.gov (United States)

    1985-08-01

    This discussion of Honduras covers the following: the history of the country's demographic situation; the government's overall approach to population problems; population data systems and development planning; institutional arrangements for the integration of population within development planning; the goverment's view of the importance of population policy in realizing development objectives; population size, growth, and natural increase; morbidity and mortality; fertility; international migration; and spatial distribution. Between the censuses of 1910-40, Honduras grew at an average annual rate of more than 1.5% per annum. The rate of population growth reached 2% per annum after 1940 and 3% after about 1955. By 1970-75 the rate of natural increase was estimated to be about 3.5% per annum, due to the net effect of a crude birthrate of 49/1000 and a crude death rate of about 14/1000. The rate of natural increase has remained around 3.5% in recent years, although the crude death rate has declined to 44/1000 and the crude death rate to about 10/1000. The government wants to substantially reduce the rate of population growth, primarily by means of modifying fertility and averting large-scale immigration of refugees in the future. It desires to reduce the country's high levels of mortality and to adjust patterns of spatial distribution, primarily to improve agricultural productivity and promote national economic intergration. The government also seeks to decrease the emigration of qualified personnel. In the past several years, the government of Honduras has increased its commitment to formulating and implementing explicit population policies as a means of attaining overall development objcetives. With a population of around 4.1 million inhabitants as of 1983, Honduras has been growing at an average annual rate of 3.4% in recent years. According to UN projections, the population is expected to grow to about 7 million by 2000. The average life expectancy at birth for

  2. Honduras.

    Science.gov (United States)

    1987-02-01

    Honduras is a democratic, constitutional republic located between Guatemala, El Salvador, and Nicaragua in Central America. Although in the early history of the nation there were frequent revolutions, Honduras has been independent throughout much of its existence. Since the decade of the 1980s, there has been close cooperation with the US including bilateral economic and security assistance, and joint military exercises. The government constitution adopted in 1982 assures that there will be a powerful executive branch, a unicameral legislature, and a judiciary appointed by the National Congress. Following 18 years of military government, Honduras is now under civilian and constitutional rule. Its major serious concerns center around development in the economic and social spheres. Honduras is the least developed Central American country. In 1984, it became a Caribbean Basin Initiative beneficiary country and as a result, the research and development of nontraditional export products has grown greatly. The US has been its most important trade partner. Among others, the US and the World Bank have committed large amounts of financial resources to help Honduras. Honduras and El Salvador are attempting to come to some agreement about their mutual boundaries and Honduras is concerned about the Nicaraguan and general Central American situation. It supports the US position and policy toward Nicaragua. In response to the threats posed by some of its neighbors, Honduras has focused on developing a mobile deterrent force with strong counterterrorism capabilities. Honduras relies heavily on US material assistance and political support.

  3. Honduras.

    Science.gov (United States)

    1989-09-01

    Honduras is a country with an area of 68,000 square miles, with considerable mountainous terrain, and a subtropical but variable climate. It has a population of 4.4 million people and an annual growth rate of 3.1%. The ethnic make up is 90% mestizo, a mixture of Indian and European, with others consisting of Arab, African, oriental, and Indians. The main religion is Catholic with a fast growing Protestant minority, and the language is Spanish. Infant mortality is 60/1000 and life expectancy is 63 years. The work force is mainly agricultural 63%, services 20%, manufacturing 9%, and construction 3%. The government is a democratic constitutional republic established in 1821. The budget is $1,334 million with 7% used for defense, and the gross national product is $4.4 billion with an annual growth rate of 4.5%. Despite being poor and underdeveloped, natural resources include arable land, hydro- electric power, and considerable forest, marine, and mineral resources. Agriculture products include coffee, bananas, citrus fruit, corn, beans, and livestock. The major industries are textiles, cement, wood products, cigars and foodstuffs. Unemployment is over 15% and underemployment is estimated over 40% with the literacy rate at only 60%. In the last few years with US aid the economy has grown 3.8% a year assisted by mining, construction and the service sectors. Honduras must undertake major economic reforms to gain longterm growth and stability since it has large fiscal and trade deficits, a large public bureaucracy, poorly run state enterprises and overvalued exchange rate.

  4. Honduras.

    Science.gov (United States)

    1992-05-01

    Honduras has an area of 112,088 square km or 43,277 square miles with a population of 4.8 million in 1991 of whom 90% are mestizos. Literacy is 68%, the infant mortality rate is 60/1000, and life expectancy is 63 years. After independence from Spain in 1821 the Central American Federation collapsed in 1938. There have been 300 internal rebellions since independence. With an inadequate economic infrastructure, sociopolitical integration has been fragile. In 1982 the Suazo government relied on US support to face the economic recession, the threat posed by the Marxist government in Nicaragua, and civil war in El Salvador. USAID sponsored ambitious social and economic projects. A peaceful transfer of power between civilian presidents occurred in 1986 despite an electoral quirk. In 1990 President Callejas introduced reforms to reduce the deficit, and to stimulate investments and exports. After initial higher inflation and low growth in 1990 and 1991, modest progress is forecast for 1992 and 1993. The powerful military has been kept in check, and human rights have been better protected. The country is among the poorest in Latin America with underemployment of 30-40% and a mostly agricultural economy. The 1990 reforms of deregulation of prices, liberalization of trade, less protectionism, and export orientation is expected to produce longterm benefits not only in agriculture but also in manufacturing. The US is the primary trading partner, and the main direct foreign investor (fruits, refining, and mining). The slash-and-burn agricultural cultivation has created environmental destruction, and as a sign of public awareness the armed forces have engaged in reforestation and fighting forest fires.

  5. Surnames in Honduras: A study of the population of Honduras through isonymy.

    Science.gov (United States)

    Herrera Paz, Edwin Francisco; Scapoli, Chiara; Mamolini, Elisabetta; Sandri, Massimo; Carrieri, Alberto; Rodriguez-Larralde, Alvaro; Barrai, Italo

    2014-05-01

    In this work, we investigated surname distribution in 4,348,021 Honduran electors with the aim of detecting population structure through the study of isonymy in three administrative levels: the whole nation, the 18 departments, and the 298 municipalities. For each administrative level, we studied the surname effective number, α, the total inbreeding, FIT , the random inbreeding, FST , and the local inbreeding, FIS . Principal components analysis, multidimensional scaling, and cluster analysis were performed on Lasker's distance matrix to detect the direction of surname diffusion and for a graphic representation of the surname relationship between different locations. The values of FIT , FST , and FIS display a variation of random inbreeding between the administrative levels in the Honduras population, which is attributed to the "Prefecture effect." Multivariate analyses of department data identified two main clusters, one south-western and the second north-eastern, with the Bay Islands and the eastern Gracias a Dios out of the main clusters. The results suggest that currently the population structure of this country is the result of the joint action of short-range directional migration and drift, with drift dominating over migration, and that population diffusion may have taken place mainly in the NW-SE direction.

  6. Population data for 12 Y-chromosome STR loci in a sample from Honduras.

    Science.gov (United States)

    Matamoros, Mireya; Yurrebaso, Iñaki; Gusmão, Leonor; García, Oscar

    2009-09-01

    Haplotype, allele frequencies and population data of 12 Y-chromosome STR loci DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438 and DYS439 were determined from a sample of 128 unrelated male individuals from Honduras, Central America. A total of 112 haplotypes were identified by the 12 Y-STR loci of which 98 were unique. The haplotype diversity (98.99%) and the proportion of different haplotypes (87.50%) were estimated. Genetic distances were calculated between Honduras and other populations from Southern and Central America, Europe and Africa. The analysis of a Multi Dimensional Scaling (MDS) plot, based on pairwise R(ST) genetic distances, allowed to conclude that Honduras is highly differentiated from the African samples (0.343Honduras showed a lower genetic distance to the European cluster (composed by European and South American general population samples from Brazil, Argentina, Colombia and Venezuela) than to the Central American cluster (Mexico and El Salvador).

  7. Migration, Multiple Sexual Partnerships, and Sexual Concurrency in the Garífuna Population of Honduras.

    Science.gov (United States)

    Gandhi, Anisha D; Pettifor, Audrey; Barrington, Clare; Marshall, Stephen W; Behets, Frieda; Guardado, Maria Elena; Farach, Nasim; Ardón, Elvia; Paz-Bailey, Gabriela

    2015-09-01

    The Garífuna, an ethnic minority group in Honduras, have been disproportionately affected by HIV. Previous research suggests that migration and high rates of multiple sexual partnerships are major drivers of the epidemic. Using data from a 2012 population-based survey, we assessed whether temporary migration was associated with (1) multiple sexual partnerships and (2) sexual concurrency among Garífuna men and women in Honduras. Among both men and women, temporary migration in the last year was associated with an increased likelihood of multiple sexual partnerships and with concurrency, though only the association between migration and multiple sexual partnerships among men was statistically significant (Adjusted Prevalence Ratio 1.7, 95 % CI 1.2-2.4). Migration may contribute to HIV/STI vulnerability among Garífuna men and women via increases in these sexual risk behaviors. Research conducted among men and women at elevated risk of HIV should continue to incorporate measures of mobility, including history of internal migration.

  8. Population dynamics

    Directory of Open Access Journals (Sweden)

    Cooch, E. G.

    2004-06-01

    Full Text Available Increases or decreases in the size of populations over space and time are, arguably, the motivation for much of pure and applied ecological research. The fundamental model for the dynamics of any population is straightforward: the net change over time in the abundance of some population is the simple difference between the number of additions (individuals entering the population minus the number of subtractions (individuals leaving the population. Of course, the precise nature of the pattern and process of these additions and subtractions is often complex, and population biology is often replete with fairly dense mathematical representations of both processes. While there is no doubt that analysis of such abstract descriptions of populations has been of considerable value in advancing our, there has often existed a palpable discomfort when the ‘beautiful math’ is faced with the often ‘ugly realities’ of empirical data. In some cases, this attempted merger is abandoned altogether, because of the paucity of ‘good empirical data’ with which the theoretician can modify and evaluate more conceptually–based models. In some cases, the lack of ‘data’ is more accurately represented as a lack of robust estimates of one or more parameters. It is in this arena that methods developed to analyze multiple encounter data from individually marked organisms has seen perhaps the greatest advances. These methods have rapidly evolved to facilitate not only estimation of one or more vital rates, critical to population modeling and analysis, but also to allow for direct estimation of both the dynamics of populations (e.g., Pradel, 1996, and factors influencing those dynamics (e.g., Nichols et al., 2000. The interconnections between the various vital rates, their estimation, and incorporation into models, was the general subject of our plenary presentation by Hal Caswell (Caswell & Fujiwara, 2004. Caswell notes that although interest has traditionally

  9. Short communication: HIV incidence among vulnerable populations in Honduras: results from an integrated behavioral and biological survey among female sex workers, men who have sex with men, and Garifuna in Honduras, 2006.

    Science.gov (United States)

    Kim, Andrea A; Morales, Sonia; Lorenzana de Rivera, Ivette; Paredes, Mayte; Juarez, Sandra; Alvarez, Berta; Liu, Xin; Parekh, Bharat; Monterroso, Edgar; Paz-Bailey, Gabriela

    2013-03-01

    Honduras has one of the highest HIV prevalence rates in Central America. Data on HIV incidence are needed to identify groups at greatest need of prevention interventions to inform the national HIV response. We applied a test for recent infection to HIV-positive specimens from a biological and behavioral survey to estimate assay-derived incidence among men who have sex with men (MSM), female sex workers (FSW), and the Garifuna population in Honduras. Assay-derived estimates were compared to the mathematically modeled estimates in the same populations to assess plausibility of the assay-based estimates. Assay-derived incidence was 1.1% (95% CI 0.2-2.0) among MSM, 0.4% (95% CI 0.1-0.8) among the Garifuna, and 0% (95% CI 0-0.01) among FSWs. The modeled incidence estimates were similar at 1.03% among MSM, 0.30% among the Garifuna, and 0.23% among FSWs. HIV incidence based on the assay was highest among MSM in Honduras, lowest among FSWs, and similar to modeled incidence in these groups. Targeted programs on HIV prevention, care, and treatment are urgently needed for the MSM population. Continued support for existing prevention programs for FSWs and Garifuna are recommended.

  10. Intestinal parasitic infections and eosinophilia in an human immunedeficiency virus positive population in Honduras

    Directory of Open Access Journals (Sweden)

    Rina G Kaminsky

    2004-11-01

    Full Text Available The occurrence of intestinal parasites, their regional distribution and their relations to eosinophilia were studied in 133 human immunodeficiency virus (HIV positive individuals from Honduras. After signing an informed consent, participants answered a socio-demographic and risk factor questionnaire, a complete physical examination, medical history, and a series of laboratory tests. All participants were HIV positive but not acquired immunodeficiency syndrome positive. Of them, 67% were co-infected with pathogen and non pathogen parasites. Overall occurrence of nematodes was: 44.3% for Trichuris trichiura, 24% for Ascaris lumbricoides, 12% for Hookworm and 7.5% for Strongyloides stercoralis. No cases of Giardia lamblia, acute amebiasis or cryptosporidiasis were diagnosed. Mean eosinophil percents for participants were consistently and significantly higher in infected than in non infected individuals: 22% for Hookworm vs 7.2% (p < 0.001, 11% for Trichuris compared to 5.2% (p < 0.001, 13.2% compared to 7.5% for S. stercoralis (p < 0.05, and 12% compared to 6% for Ascaris cases (p < 0.05. Helminths and non pathogenic protozoa, as single or mixed infections, occurred among the participants. There was a strong correlation between eosinophilia and helminthiasis infections; however, none was identified between CD4 levels and eosinophilia. Because parasitic infections aggravate malnutrition and promote a disbalanced Th2 response in a potentially immuno-compromised host, their effect on HIV disease progression needs further study, mainly in countries were HIV and parasitic infections are highly prevalent.

  11. A Sustainable and Resilient Housing Model for Indigenous Populations of the Mosquitia Region (Honduras

    Directory of Open Access Journals (Sweden)

    Valeria Gambino

    2014-08-01

    Full Text Available This study develops a sustainable housing model for the Mosquitia region of Honduras, aimed at improving the living conditions of indigenous communities and reducing their vulnerability to the effects of climate change. The improved housing efficiency and resilience will contribute to strengthen sanitation and hygiene, improve the living comfort and reduce environmental impact, particularly focusing on preserving the forest biodiversity. The project was developed following the criteria of environmental, technical, social and economic sustainability to propose a shared model, reproducible by the beneficiaries living in different kinds of Mosquitian ecosystems. Increased building efficiency is obtained through optimization of construction techniques and improvement of materials’ performances. The main material of the proposed dwelling is wood, coherently with the “Miskita” tradition; the increase of its durability, which is obtained by proper seasoning and protection from atmospheric agents and parasites, contributes to the optimization of the use of this natural resource and to reducing the impact on deforestation, which threatens forest biodiversity. The data collection campaign, conducted before developing the housing model design and which has aimed at obtaining information on technical and social aspects related to residences’ welfare and health conditions, has highlighted the great importance of improving the construction model. Despite the advance in sanitary conditions and the economic level, the data collection campaign revealed that even the most developed communities amongst those visited have been perpetrating substantial construction errors, which reduce the resilience of structures to extreme natural phenomena, such as tropical storms and hurricanes, which frequently affect the Mosquitia region. This unexpected discovery increased the importance of housing model design in order to correct these improper construction

  12. Physical and Sexual Violence, Mental Health indicators, and treatment seeking among street-based population groups in Tegucigalpa, Honduras

    OpenAIRE

    Rio Navarro, Javier; Cohen, Julien; Rocillo Arechaga, Eva; Zuniga, Edgardo

    2012-01-01

    To establish the prevalence of exposure to physical and sexual violence, mental health symptoms, and medical treatment-seeking behavior among three street-based subpopulation groups in Tegucigalpa, Honduras, and to assess the association between sociodemographic group, mental health indicators, and exposure to violence.

  13. Honduras: Caribbean Coast

    Energy Technology Data Exchange (ETDEWEB)

    Harborne, Alastair R.; Afzal, Daniel C.; Andrews, Mark J. [Coral Cay Conservation, London (United Kingdom)

    2001-07-01

    The coast of Honduras, Central America, represents the southern end of the Mesoamerican Barrier Reef System, although its marine resources are less extensive and studied than nearby Belize and Mexico. However, the coastal zone contains mainland reef formations, mangroves, wetlands, seagrass beds and extensive fringing reefs around its offshore islands, and has a key role in the economy of the country. Like most tropical areas, this complex of benthic habitats experiences limited annual variation in climatic and oceanographic conditions but seasonal and occasional conditions, particularly coral bleaching and hurricanes, are important influences. The effects of stochastic factors on the country's coral reefs were clearly demonstrated during 1998 when Honduras experienced a major hurricane and bleaching event. Any natural or anthropogenic impacts on reef health will inevitably affect other countries in Latin America, and vice versa, since the marine resources are linked via currents and the functioning of the system transcends political boundaries. Much further work on, for example, movement of larvae and transfer of pollutants is required to delineate the full extent of these links. Anthropogenic impacts, largely driven by the increasing population and proportion of people living in coastal areas, are numerous and include key factors such as agricultural run-off, over-fishing, urban and industrial pollution (particularly sewage) and infrastructure development. Many of these threats act synergistically and, for example, poor watershed management via shifting cultivation, increases sedimentation and pesticide run-off onto coral reefs, which increases stress to corals already affected by decreasing water quality and coral bleaching. Threats from agriculture and fishing are particularly significant because of the size of both industries. The desire to generate urgently required revenue within Honduras has also led to increased tourism which provides an over

  14. Honduras: Caribbean Coast.

    Science.gov (United States)

    Harborne, A R; Afzal, D C; Andrews, M J

    2001-12-01

    The coast of Honduras, Central America, represents the southern end of the Mesoamerican Barrier Reef System, although its marine resources are less extensive and studied than nearby Belize and Mexico. However, the coastal zone contains mainland reef formations, mangroves, wetlands, seagrass beds and extensive fringing reefs around its offshore islands, and has a key role in the economy of the country. Like most tropical areas, this complex of benthic habitats experiences limited annual variation in climatic and oceanographic conditions but seasonal and occasional conditions, particularly coral bleaching and hurricanes, are important influences. The effects of stochastic factors on the country's coral reefs were clearly demonstrated during 1998 when Honduras experienced a major hurricane and bleaching event. Any natural or anthropogenic impacts on reef health will inevitably affect other countries in Latin America, and vice versa, since the marine resources are linked via currents and the functioning of the system transcends political boundaries. Much further work on, for example, movement of larvae and transfer of pollutants is required to delineate the full extent of these links. Anthropogenic impacts, largely driven by the increasing population and proportion of people living in coastal areas, are numerous and include key factors such as agricultural run-off, over-fishing, urban and industrial pollution (particularly sewage) and infrastructure development. Many of these threats act synergistically and, for example, poor watershed management via shifting cultivation, increases sedimentation and pesticide run-off onto coral reefs, which increases stress to corals already affected by decreasing water quality and coral bleaching. Threats from agriculture and fishing are particularly significant because of the size of both industries. The desire to generate urgently required revenue within Honduras has also led to increased tourism which provides an overarching stress

  15. Alternative Education Programmes and Middle School Dropout in Honduras

    Science.gov (United States)

    Marshall, Jeffery H.; Aguilar, Claudia R.; Alas, Mario; Castellanos, Renán Rápalo; Castro, Levi; Enamorado, Ramón; Fonseca, Esther

    2014-01-01

    Honduras has made steady progress in expanding post-primary school coverage in recent years, but many rural communities still do not provide a middle (lower secondary) school. As a result, Honduras has implemented a number of middle school alternative programmes designed to meet the needs of at-risk populations throughout the country. This article…

  16. Market Squid Population Dynamics

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains population dynamics data on paralarvae, juvenile and adult market squid collected off California and the US Pacific Northwest. These data were...

  17. Population dynamics of reindeer

    Directory of Open Access Journals (Sweden)

    L. M. Baskin

    1990-09-01

    Full Text Available Five types of reindeer populations are distinguished in terms of population dynamics, population density, social structure and migration distance. Differences in the biological rhythms of the populations result in calving occuring 20 days before snow melting in all populations as well as maximal utilization by the deer of young green vegetation in summer. The growth of antlers may serve as a regulatior of biological rhytms. Populations differ in the level of social motivation. Formation of groups of not less than 30-35 animals ensures cooperative protection from insects and management of the group by man. The fidelity to the calving sites, summer ranges and constant migration routes is based on the common orientation reactions of the animals and social attraction. The direction and migration routes are detemined by obligate learning. The dynamics of populations depends on the fertility of 2 and 3 year old females which is determined by feeding conditions in summer and the activity of males during the rut. Migration plays an important role in the population dynamics.

  18. Divergence in morphology, but not habitat use, despite low genetic differentiation among insular populations of the lizard Anolis lemurinus in Honduras

    Science.gov (United States)

    Logan, M.L.; Montgomery, Chad E.; Boback, Scott M.; Reed, R.N.; Campbell, J.A.

    2012-01-01

    Studies of recently isolated populations are useful because observed differences can often be attributed to current environmental variation. Two populations of the lizard Anolis lemurinus have been isolated on the islands of Cayo Menor and Cayo Mayor in the Cayos Cochinos Archipelago of Honduras for less than 15 000 y. We measured 12 morphometric and 10 habitat-use variables on 220 lizards across these islands in 2 y, 2008 and 2009. The goals of our study were (1) to explore patterns of sexual dimorphism, and (2) to test the hypothesis that differences in environment among islands may have driven divergence in morphology and habitat use despite genetic homogeneity among populations. Although we found no differences among sexes in habitat use, males had narrower pelvic girdles and longer toe pads on both islands. Between islands, males differed in morphology, but neither males nor females differed in habitat use. Our data suggest that either recent selection has operated differentially on males despite low genetic dill'erentiation, or that they display phenotypic plasticity in response to environmental variation. We suggest that patterns may be driven by variation in intrapopulation density or differences in predator diversity among islands.

  19. Honduras Defense Policy.

    Science.gov (United States)

    1986-04-22

    and its Organization .......... 14 Civil -Military Relations ............................17 Impact of the Military on the Government ........... 18 Ill...Discovered by Columbus in his last voyage in August 1502, Honduras was part of the Mayan Empire that flourished throughout Southern Mexico, Guatemala...34 + " ’- " - ’ ] , . i + .°, +,.o .r+ .* -- 7--- -. * - I . .. .. early 1930’s. Civil wars, armed revolts and political struggle for power was the common denominator

  20. Monitored and modeled coral population dynamics and the refuge concept.

    Science.gov (United States)

    Riegl, B; Purkis, S J; Keck, J; Rowlands, G P

    2009-01-01

    With large-scale impacts on coral reefs due to global climatic change projected to increase dramatically, and suitability of many areas for reef growth projected to decrease, the question arises whether particular settings might serve as refugia that can maintain higher coral populations than surrounding areas. We examine this hypothesis on a small, local scale in Honduras, western Caribbean. Dense coral thickets containing high numbers of the endangered coral Acropora cervicornis occur on offshore banks while being rare on the fringing reef on nearby Roatán. Geomorphological setting and community dynamics were evaluated and monitored from 1996 to 2005. A model of population dynamics was developed to test assumptions derived from monitoring. Coral cover on the fringing reef declined in 1998 from >30% to causes good flushing. Only four A. cervicornis recruits were recorded on the fringing reef over 6 years. Runoff associated with hurricanes caused greater mortality than did bleaching in 1998 and 2005 on the fringing reef, but not on the banks. Since 1870, our analysis suggests that corals on the banks may have been favored during 17 runoff events associated with tropical depressions and storms and potentially also during five bleaching events, but this is more uncertain. Our model suggests that under this disturbance regime, the banks will indeed maintain higher coral populations than the fringing reef and supports the assumption that offshore banks could serve as refugia with the capacity to subsidize depleted mainland populations.

  1. Honduras: Will the Revolution Come?

    Science.gov (United States)

    1983-06-03

    2. GOVERNMENT DOCUMENTS. Banco Central de Honduras. Honduras en Cifras. Tegucigalpa, D.C. Departamento de Estudios Economicos , 1980. Blutstein...Tegucigalpa D. C. Departamento de Estuidios Economicos , 1980), p. 13 1 8 Agency, Op Cit., p. 9 1 9 Ibid, p. 9 25 ’A’ V~~~... .... X~l-V’ 2 0 Interview

  2. Drug resistance prevalence in human immunodeficiency virus type 1 infected pediatric populations in Honduras and El Salvador during 1989-2009.

    Science.gov (United States)

    Holguín, Africa; Erazo, Karen; Escobar, Gustavo; de Mulder, Miguel; Yebra, Gonzalo; Martín, Leticia; Jovel, Luis Enrique; Castaneda, Luis; Pérez, Elsy

    2011-05-01

    Emergence of viral resistance is a major obstacle for antiretroviral treatment (ART) effectiveness. Human immunodeficiency virus type-1 (HIV-1) variants and drug-resistance mutations were identified in naive and antiretroviral drug-experienced children with virologic failure, in Honduras and El Salvador. Dried blood spots (DBS) from 80 individuals (54 from Honduras, 26 from El Salvador) infected during their childhood between 1989 and 2009 were collected in 2009. The HIV pol region was amplified and sequenced to identify antiretroviral-resistant mutations according to the 2009 International AIDS Society. The genotypic drug resistance interpretation was performed using the Stanford algorithm. HIV-1 variants were characterized by phylogenetic analysis and subtyping tools. HIV-1 protease and reverse transcription sequences were obtained from DBS specimens in 71 and 66 patients, respectively, of the 80 patients. All children were native Central Americans carrying subtype B, with a mean age of 9 years, most were male (65%), perinatally infected (96%), with moderate/severe AIDS symptoms (70%), and receiving first line ART at the time of sequencing (65%). Diagnostic delay was frequently observed. Infected children from Honduras presented longer ART experience and clinical outcomes, and more frequent severe symptoms. Resistant variants infected 1 of 11 naive children from El Salvador but none of the perinatally infected naive children from Honduras. Resistance was higher among ART-exposed individuals in both countries and similar for protease inhibitors (16%), nucleoside reverse transcription inhibitors (44%-52%), and nonnucleoside reverse-transcription inhibitors (66.7%). One in 10 pretreated children in each country was infected with resistant viruses to the 3 drug families. Our data support the need for continued surveillance of resistance patterns using DBS at national levels among naive and pretreated children to optimize the ART regimens.

  3. Language dynamics in finite populations.

    Science.gov (United States)

    Komarova, Natalia L; Nowak, Martin A

    2003-04-01

    Any mechanism of language acquisition can only learn a restricted set of grammars. The human brain contains a mechanism for language acquisition which can learn a restricted set of grammars. The theory of this restricted set is universal grammar (UG). UG has to be sufficiently specific to induce linguistic coherence in a population. This phenomenon is known as "coherence threshold". Previously, we have calculated the coherence threshold for deterministic dynamics and infinitely large populations. Here, we extend the framework to stochastic processes and finite populations. If there is selection for communicative function (selective language dynamics), then the analytic results for infinite populations are excellent approximations for finite populations; as expected, finite populations need a slightly higher accuracy of language acquisition to maintain coherence. If there is no selection for communicative function (neutral language dynamics), then linguistic coherence is only possible for finite populations.

  4. Dinámica del nitrógeno y el fósforo del suelo bajo tres sistemas de uso de la tierra en laderas de Honduras Dynamics of soil nitrogen and phosphorus in three land use systems on hillsides of Honduras

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    Aracely Castro

    2010-10-01

    Full Text Available Se condujo un estudio para determinar el efecto de los principios de manejo del Sistema Agroforestal Quesungual (SAQ en la dinámica de nitrógeno (N y fósforo (P del suelo y el impacto de estos en su productividad en el sur-occidente de Honduras, Centroamérica. Se compararon cinco sistemas: (1 tala-y-quema (TQ; (2, 3 & 4 SAQ de A study was carried out to determine the effect of management principles in the Quesungual Slash and Mulch Agroforestry System (QSMAS on the dynamics of soil nitrogen (N and phosphorus (P, and their impact on QSMAS’ productivity in southwestern Honduras, Central America. Five land use systems were compared: (1 Slash-and-burn traditional system; (2, 3 and 4 QSMAS of 10 years old, respectively; and (5 Secondary forest. Local practices were applied to produce maize Zea mays, and bean Phaseolus vulgaris, with (101 kg N + 55 kg P /ha for maize, 46 kg N + 51 kg P /ha for bean and without addition of fertilizers. Measurements included decomposition and nutrient release from biomass, aerobic mineralization of N, sequential fractionation of P, size-density fractionation of soil organic matter, and crop yield. Similarities in N dynamics indicate that QSMAS and slash-and-burn system were equally effective in providing N, although in QSMAS it is also result of a biologically mediated process. P pools in QSMAS were more dynamic and favorable by reducing their flows towards unavailable forms. Based on nutrient availability and grain yields over time, QSMAS could be a suitable option to replace the slash-and-burn system in smallholder agroecosystems.

  5. AMPHIBIAN POPULATION DYNAMICS

    Science.gov (United States)

    Agriculture has contributed to loss of vertebrate biodiversity in many regions, including the U.S. Corn Belt. Amphibian populations, in particular, have experienced widespread and often inexplicable declines, range reductions, and extinctions. However, few attempts have been made...

  6. Rapid ongoing decline of Baird's tapir in Cusuco National Park, Honduras.

    Science.gov (United States)

    McCann, Niall P; Wheeler, Phil M; Coles, Tim; Bruford, Michael W

    2012-12-01

    During the International Tapir Symposium 16-21 Oct 2011, the conservation of Baird's tapir (Tapirus bairdii) in Honduras received a boost with the signing of a memorandum of understanding between the Minister Director of the Honduran Institute of Conservation and Forestry (ICF) and the Tapir Specialist Group (TSG). Despite this agreement, accelerating levels of hunting and habitat loss continue to pose a threat to Baird's tapir in Honduras. An ongoing study in Cusuco National Park in northwestern Honduras has been monitoring changes in population dynamics of Baird's tapir since 2006 through the collection of occupancy data. The study has identified an increase in hunting pressure, coinciding with a drastic decline in the encounter rate with Baird's tapir spoor. Here, we examine the significance of a range of demographic variables on Baird's tapir occupancy in Cusuco National Park using the software PRESENCE, and simulate the effects of different management strategies on the future dynamics of the population using the stochastic simulation software VORTEX. The predictions of the theoretical population models are compared to observed changes in occupancy levels. We found that non-intervention resulted in the local extinction of Baird's tapir within a very short time frame, but that various intervention models enabled the population to recover to near carrying capacity. Occupancy and extinction probability were shown to respond markedly to the increase in hunting pressure; and occupancy models supported the future population predictions generated by VORTEX. Our study suggests that immediate intervention is required to reduce hunting pressure to near historical levels to prevent the imminent local extinction of the species.

  7. Amphibian chytrid fungus Batrachochytrium dendrobatidis in Cusuco National Park, Honduras.

    Science.gov (United States)

    Kolby, Jonathan E; Padgett-Flohr, Gretchen E; Field, Richard

    2010-11-01

    Amphibian population declines in Honduras have long been attributed to habitat degradation and pollution, but an increasing number of declines are now being observed from within the boundaries of national parks in pristine montane environments. The amphibian chytrid fungus Batrachochytrium dendrobatidis has been implicated in these declines and was recently documented in Honduras from samples collected in Pico Bonito National Park in 2003. This report now confirms Cusuco National Park, a protected cloud forest reserve with reported amphibian declines, to be the second known site of infection for Honduras. B. dendrobatidis infection was detected in 5 amphibian species: Craugastor rostralis, Duellmanohyla soralia, Lithobates maculata, Plectrohyla dasypus, and Ptychohyla hypomykter. D. soralia, P. dasypus, and P. hypomykter are listed as critically endangered in the IUCN Red List of Threatened Species and have severely fragmented or restricted distributions. Further investigations are necessary to determine whether observed infection levels indicate an active B. dendrobatidis epizootic with the potential to cause further population declines and extinction.

  8. Africa population dynamics

    NARCIS (Netherlands)

    Akinyoade, A.; Damen, J.C.M.; Dietz, A.J.; Kilama, B.; Omme, van G.

    2014-01-01

    Africa's population has grown extremely rapidly over the last fifty years from 289 million inhabitants in 1961 to more than 1 billion today. This is a growth rate of 350% in just half a century and the number of urban residents has increased even more quickly: from 65 million in 1960 to 460 million

  9. Sistema de salud de Honduras The health system of Honduras

    Directory of Open Access Journals (Sweden)

    Juan Luis Bermúdez-Madriz

    2011-01-01

    Full Text Available En este trabajo se describe el sistema de salud de Honduras, incluyendo los retos que enfrenta, su estructura y cobertura, su financiamiento, los recursos con los que cuenta y las actividades de rectoría que en él se desarrollan. Este sistema cuenta con un sector público constituido por la Secretaría de Salud (SS y el Instituto Hondureño de Seguridad Social (IHSS, y un sector privado en el que predomina el uso de servicios con pago de bolsillo. El Plan Nacional de Salud 2010-2014 se plantea una ambiciosa reforma del sistema que contempla la universalización del aseguramiento mediante un sistema de salud integrado y plural, en el que la SS funcionaría como una institución rectora y reguladora, y que contaría con un seguro público nacional de salud para la población pobre y un IHSS que funcionaría exclusivamente como aseguradora al contratar servicios para sus afiliados con proveedores públicos y privados, que operarían bajo un modelo de salud familiar y comunitaria.This paper describes the health system of Honduras, including its challenges, structure coverage, sources of financing, resources and stewardship activities. This system counts with a public and a private sector. The public sector includes the Ministry of Health (MH and the Honduran Social Security Institute (HSSI. The private sector is dominated by a set of providers offering services payed mostly out-of-pocket. The National Health Plan 2010-2014 includes a set of reforms oriented towards the creation of an integrated and plural system headed by the MH in its stewardship role. It also anticipates the creation of a public health insurance for the poor population and the transformation of the HSSI into a public insurance agency which contracts services for its affiliates with public and private providers under a family medicine model.

  10. Dynamical systems in population biology

    CERN Document Server

    Zhao, Xiao-Qiang

    2017-01-01

    This research monograph provides an introduction to the theory of nonautonomous semiflows with applications to population dynamics. It develops dynamical system approaches to various evolutionary equations such as difference, ordinary, functional, and partial differential equations, and pays more attention to periodic and almost periodic phenomena. The presentation includes persistence theory, monotone dynamics, periodic and almost periodic semiflows, basic reproduction ratios, traveling waves, and global analysis of prototypical population models in ecology and epidemiology. Research mathematicians working with nonlinear dynamics, particularly those interested in applications to biology, will find this book useful. It may also be used as a textbook or as supplementary reading for a graduate special topics course on the theory and applications of dynamical systems. Dr. Xiao-Qiang Zhao is a University Research Professor at Memorial University of Newfoundland, Canada. His main research interests involve applied...

  11. Population dynamics in variable environments

    CERN Document Server

    Tuljapurkar, Shripad

    1990-01-01

    Demography relates observable facts about individuals to the dynamics of populations. If the dynamics are linear and do not change over time, the classical theory of Lotka (1907) and Leslie (1945) is the central tool of demography. This book addresses the situation when the assumption of constancy is dropped. In many practical situations, a population will display unpredictable variation over time in its vital rates, which must then be described in statistical terms. Most of this book is concerned with the theory of populations which are subject to random temporal changes in their vital rates, although other kinds of variation (e. g. , cyclical) are also dealt with. The central questions are: how does temporal variation work its way into a population's future, and how does it affect our interpretation of a population's past. The results here are directed at demographers of humans and at popula­ tion biologists. The uneven mathematical level is dictated by the material, but the book should be accessible to re...

  12. Models of ungulate population dynamics

    Directory of Open Access Journals (Sweden)

    L. L. Eberhardt

    1991-10-01

    Full Text Available A useful theory for analyzing ungulate population dynamics is available in the form of equations based on the work of A. J. Lotka. Because the Leslie matrix model yields identical results and is widely known, it is convenient to label the resulting equations as the "Lotka-Leslie" model. The approach is useful for assessing population trends and attempting to predict the outcomes of various management actions. A broad list of applications to large mammals, and two examples specific to caribou are presented with a simple spreadsheet approach to calculations.

  13. Mapa de Vulnerabilidad en Honduras

    Science.gov (United States)

    Sánchez, A. A.

    2013-05-01

    Dado que Honduras geográficamente se encuentra en una zona que esta expuesta a diferentes fenómenos sísmicos y climatológicos. Investigamos cuales son las zonas mas propensas a desastres naturales, la vulnerabilidad y el factor de resiliencia de la población de acuerdo a diferentes parámetros de estudio.

  14. Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras

    Directory of Open Access Journals (Sweden)

    Lopez Ana

    2012-11-01

    Full Text Available Abstract Background Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite’s circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Methods Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. Results and conclusion A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77 for pvama-1; 23 (n = 84 for pvcsp; and 23 (n = 35 for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2 was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30 block 2 (K1, MAD20, and RO33, and both allelic families described for the central domain of pfmsp-2 (n = 11 (3D7 and FC27 were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

  15. Nonlinear dynamics of interacting populations

    CERN Document Server

    Bazykin, Alexander D

    1998-01-01

    This book contains a systematic study of ecological communities of two or three interacting populations. Starting from the Lotka-Volterra system, various regulating factors are considered, such as rates of birth and death, predation and competition. The different factors can have a stabilizing or a destabilizing effect on the community, and their interplay leads to increasingly complicated behavior. Studying and understanding this path to greater dynamical complexity of ecological systems constitutes the backbone of this book. On the mathematical side, the tool of choice is the qualitative the

  16. The herpetofauna of Parque Nacional Pico Bonito, Honduras

    Directory of Open Access Journals (Sweden)

    James R. McCranie

    2005-10-01

    Full Text Available Seventy-three species of amphibians and reptiles (six salamanders, 20 anurans, 20 lizards, and 27 snakes are known from Parque Nacional Pico Bonito, Honduras. The physiography, climate, vegetation, and microhabitats of the park are briefly described. Forty-four species are recorded from Lowland Moist Forest, 45 from Premontane Wet Forest, and 14 from Lower Montane Wet Forest. The primary microhabitat and relative abundance of each species are indicated and population declines are discussed.

  17. Analysis of Population Dynamics in World Economy

    OpenAIRE

    Martin, Gress

    2011-01-01

    Population dynamics is an important topic in current world economy. The size and growth of population have an impact on economic growth and development of individual countries and vice versa, economic development influences demographic variables in a country. The aim of the article is to analyze historical development of world population, population stock change and relations between population stock change and economic development.

  18. Breastfeeding promotion in Honduras: the PROALMA project.

    Science.gov (United States)

    1987-01-01

    The Honduras PROALMA project was launched in 1982 with the objectives of postponing the early introduction of supplemental foods to infants being breastfed, decrease the rate of bottle feeding, and increase the duration of breastfeeding. PROALMA was initiated as a joint project of the Ministry of Public Health, the National Social Security Institute, and the National Social Welfare Agency. Program efforts are concentrated in urban populations in 2 cities: Tegucigalpa and San Pedro Sula. The PROALMA project is an example of how breastfeeding promotion activities can influence feeding practices. The project shows that the duration of breastfeeding can be extended when hospital practices are changed and health professionals are trained in appropriate breastfeeding management techniques. Changes such as eliminating the routine use of supplemental formula and encouraging rooming-in resulted in successful initiation of breastfeeding in the hospital. The proportion of health professionals recommending breastfeeding increased from under 40% in 1982 to over 75% in 1985. The Maternal and Child Hospital in Tegucigalpa estimated that changes in infant feeding practices initiated by PROALMA saved the hospital close to US$15,000/year in drug use, infant formula use, and baby bottles. Indirect savings associated with reduced morbidity of newborns are being monitored. The proportion of women who were shown how to breastfeed in the hospital increased from under 10% to 70% between 1982 and 1985. Over 70% of infants were still being breastfed at 12 months of age in 1985 compared with only 35% of these infants in 1982. Before the PROALMA program, half of all breastfeeding women introduced supplementary bottle feedings by 2 weeks of age compared with a median age of 2 1/2 months in 1985. As a result of the success of this project, it has been expanded to cover all of Honduras.

  19. Population dynamics of defensive symbionts in aphids

    National Research Council Canada - National Science Library

    Kerry M Oliver; Jaime Campos; Nancy A Moran; Martha S Hunter

    2008-01-01

    .... While laboratory studies have identified diverse beneficial effects conferred by inherited symbionts of insects, they have not explicitly examined the population dynamics of mutualist symbiont...

  20. Exploiting social influence to magnify population-level behaviour change in maternal and child health: study protocol for a randomised controlled trial of network targeting algorithms in rural Honduras

    Science.gov (United States)

    Shakya, Holly B; Stafford, Derek; Hughes, D Alex; Keegan, Thomas; Negron, Rennie; Broome, Jai; McKnight, Mark; Nicoll, Liza; Nelson, Jennifer; Iriarte, Emma; Ordonez, Maria; Airoldi, Edo; Fowler, James H; Christakis, Nicholas A

    2017-01-01

    Introduction Despite global progress on many measures of child health, rates of neonatal mortality remain high in the developing world. Evidence suggests that substantial improvements can be achieved with simple, low-cost interventions within family and community settings, particularly those designed to change knowledge and behaviour at the community level. Using social network analysis to identify structurally influential community members and then targeting them for intervention shows promise for the implementation of sustainable community-wide behaviour change. Methods and analysis We will use a detailed understanding of social network structure and function to identify novel ways of targeting influential individuals to foster cascades of behavioural change at a population level. Our work will involve experimental and observational analyses. We will map face-to-face social networks of 30 000 people in 176 villages in Western Honduras, and then conduct a randomised controlled trial of a friendship-based network-targeting algorithm with a set of well-established care interventions. We will also test whether the proportion of the population targeted affects the degree to which the intervention spreads throughout the network. We will test scalable methods of network targeting that would not, in the future, require the actual mapping of social networks but would still offer the prospect of rapidly identifying influential targets for public health interventions. Ethics and dissemination The Yale IRB and the Honduran Ministry of Health approved all data collection procedures (Protocol number 1506016012) and all participants will provide informed consent before enrolment. We will publish our findings in peer-reviewed journals as well as engage non-governmental organisations and other actors through venues for exchanging practical methods for behavioural health interventions, such as global health conferences. We will also develop a ‘toolkit’ for practitioners to

  1. Population Dynamics of Viral Inactivation

    Science.gov (United States)

    Freeman, Krista; Li, Dong; Behrens, Manja; Streletzky, Kiril; Olsson, Ulf; Evilevitch, Alex

    We have investigated the population dynamics of viral inactivation in vitrousing time-resolved cryo electron microscopy combined with light and X-ray scattering techniques. Using bacteriophage λ as a model system for pressurized double-stranded DNA viruses, we found that virions incubated with their cell receptor eject their genome in a stochastic triggering process. The triggering of DNA ejection occurs in a non synchronized manner after the receptor addition, resulting in an exponential decay of the number of genome-filled viruses with time. We have explored the characteristic time constant of this triggering process at different temperatures, salt conditions, and packaged genome lengths. Furthermore, using the temperature dependence we determined an activation energy for DNA ejections. The dependences of the time constant and activation energy on internal DNA pressure, affected by salt conditions and encapsidated genome length, suggest that the triggering process is directly dependent on the conformational state of the encapsidated DNA. The results of this work provide insight into how the in vivo kinetics of the spread of viral infection are influenced by intra- and extra cellular environmental conditions. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1252522.

  2. Population Dynamics of Genetic Regulatory Networks

    Science.gov (United States)

    Braun, Erez

    2005-03-01

    Unlike common objects in physics, a biological cell processes information. The cell interprets its genome and transforms the genomic information content, through the action of genetic regulatory networks, into proteins which in turn dictate its metabolism, functionality and morphology. Understanding the dynamics of a population of biological cells presents a unique challenge. It requires to link the intracellular dynamics of gene regulation, through the mechanism of cell division, to the level of the population. We present experiments studying adaptive dynamics of populations of genetically homogeneous microorganisms (yeast), grown for long durations under steady conditions. We focus on population dynamics that do not involve random genetic mutations. Our experiments follow the long-term dynamics of the population distributions and allow to quantify the correlations among generations. We focus on three interconnected issues: adaptation of genetically homogeneous populations following environmental changes, selection processes on the population and population variability and expression distributions. We show that while the population exhibits specific short-term responses to environmental inputs, it eventually adapts to a robust steady-state, largely independent of external conditions. Cycles of medium-switch show that the adapted state is imprinted in the population and that this memory is maintained for many generations. To further study population adaptation, we utilize the process of gene recruitment whereby a gene naturally regulated by a specific promoter is placed under a different regulatory system. This naturally occurring process has been recognized as a major driving force in evolution. We have recruited an essential gene to a foreign regulatory network and followed the population long-term dynamics. Rewiring of the regulatory network allows us to expose their complex dynamics and phase space structure.

  3. Population dynamics and population control of Galium aparine L.

    NARCIS (Netherlands)

    Weide, van der R.Y.

    1993-01-01

    The population biology of Galium aparine L. needs to be better understood, in order to be able to rationalize decisions about the short- and long-term control of this weed species for different cropping practices.A population dynamics model was developed to simulate the basic processes of the life c

  4. Honduras geothermal development: Regulations and opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.J.; Winchester, W.W.

    1994-09-01

    The US Department of Energy (DOE) through the Assistant Secretary for Policy, Planning, and Evaluation funded a project to review and evaluate existing power sector laws and regulations in Honduras. Also included in the scope of the project was a review of regulations pertaining to the privatization of state-run companies. We paid particular attention to regulations which might influence opportunities to develop and commercialize Honduras` geothermal resources. We believe that Honduras is well on the road to attracting foreign investment and has planned or has already in place much of the infrastructure and legal guarantees which encourage the influx of private funds from abroad. In addition, in light of current power rationing and Honduras` new and increasing awareness of the negative effects of power sector development on the environment, geothermal energy development is even more attractive. Combined, these factors create a variety of opportunities. The potential for private sector development of geothermal positive.

  5. Comparing models of Red Knot population dynamics

    Science.gov (United States)

    McGowan, Conor

    2015-01-01

    Predictive population modeling contributes to our basic scientific understanding of population dynamics, but can also inform management decisions by evaluating alternative actions in virtual environments. Quantitative models mathematically reflect scientific hypotheses about how a system functions. In Delaware Bay, mid-Atlantic Coast, USA, to more effectively manage horseshoe crab (Limulus polyphemus) harvests and protect Red Knot (Calidris canutus rufa) populations, models are used to compare harvest actions and predict the impacts on crab and knot populations. Management has been chiefly driven by the core hypothesis that horseshoe crab egg abundance governs the survival and reproduction of migrating Red Knots that stopover in the Bay during spring migration. However, recently, hypotheses proposing that knot dynamics are governed by cyclical lemming dynamics garnered some support in data analyses. In this paper, I present alternative models of Red Knot population dynamics to reflect alternative hypotheses. Using 2 models with different lemming population cycle lengths and 2 models with different horseshoe crab effects, I project the knot population into the future under environmental stochasticity and parametric uncertainty with each model. I then compare each model's predictions to 10 yr of population monitoring from Delaware Bay. Using Bayes' theorem and model weight updating, models can accrue weight or support for one or another hypothesis of population dynamics. With 4 models of Red Knot population dynamics and only 10 yr of data, no hypothesis clearly predicted population count data better than another. The collapsed lemming cycle model performed best, accruing ~35% of the model weight, followed closely by the horseshoe crab egg abundance model, which accrued ~30% of the weight. The models that predicted no decline or stable populations (i.e. the 4-yr lemming cycle model and the weak horseshoe crab effect model) were the most weakly supported.

  6. Stochastic population dynamic models as probability networks

    Science.gov (United States)

    M.E. and D.C. Lee. Borsuk

    2009-01-01

    The dynamics of a population and its response to environmental change depend on the balance of birth, death and age-at-maturity, and there have been many attempts to mathematically model populations based on these characteristics. Historically, most of these models were deterministic, meaning that the results were strictly determined by the equations of the model and...

  7. How Resource Phenology Affects Consumer Population Dynamics.

    Science.gov (United States)

    Bewick, Sharon; Cantrell, R Stephen; Cosner, Chris; Fagan, William F

    2016-02-01

    Climate change drives uneven phenology shifts across taxa, and this can result in changes to the phenological match between interacting species. Shifts in the relative phenology of partner species are well documented, but few studies have addressed the effects of such changes on population dynamics. To explore this, we develop a phenologically explicit model describing consumer-resource interactions. Focusing on scenarios for univoltine insects, we show how changes in resource phenology can be reinterpreted as transformations in the year-to-year recursion relationships defining consumer population dynamics. This perspective provides a straightforward path for interpreting the long-term population consequences of phenology change. Specifically, by relating the outcome of phenological shifts to species traits governing recursion relationships (e.g., consumer fecundity or competitive scenario), we demonstrate how changes in relative phenology can force systems into different dynamical regimes, with major implications for resource management, conservation, and other areas of applied dynamics.

  8. Prediction of Rainfall-Induced Landslides in Tegucigalpa, Honduras, Using a Hydro-Geotechnical Model

    Science.gov (United States)

    Garcia Urquia, Elias; Axelsson, K.

    2010-05-01

    Central America is constantly being affected by natural hazards. Among these events are hurricanes and earthquakes, capable of triggering landslides that can alter the natural landscape, destroy infrastructure and cause the death of people in the most important settlements of the region. Hurricane Mitch in October of 1998 was of particular interest for the region, since it provoked hundreds of rainfall-induced landslides, mainly in 4 different countries. Studies carried out after Hurricane Mitch have allowed researchers to identify the factors that contribute to slope instability in many vulnerable areas. As Tegucigalpa, Honduras was partially destroyed due to the various landslide and flooding events triggered by this devastating hurricane, various research teams have deepened in their investigations and have proposed measures to mitigate the effects of similar future incidents. A model coupling an infinite-slope analysis and a simple groundwater flow approach can serve as a basis to predict the occurrence of landslides in Tegucigalpa, Honduras as a function of topographic, hydrological and soil variables. A safety map showing the rainfall-triggered landslide risk zones for Tegucigalpa, Honduras is to be created. As opposed to previous safety maps in which only steady-state conditions are studied, this analysis is extended and different steady-state and quasi-dynamic scenarios are considered for comparison. For the purpose of the latter settings, a hydrological analysis that determines the rainfall extreme values and their return periods in Tegucigalpa will account for the influence of rainfall on the groundwater flow and strength of soils. It is known that the spatial distribution of various factors that contribute to the risk of landslides (i.e. soil thickness, conductivity and strength properties; rainfall intensity and duration; root strength; subsurface flow orientation) is hard to determine. However, an effort is done to derive correlations for these

  9. Recent Research on the Impact of Alternative Education Delivery Systems in Honduras.

    Science.gov (United States)

    Spaulding, Seth

    In Honduras, 88 percent of the rural population has 6 years or less of formal education. Several distance education schemes have been undertaken to address both low rural educational levels and the destruction of schools by Hurricane Mitch. This paper reports on recent studies of two distance education efforts with substantial international…

  10. Population Dynamics and Air Pollution

    DEFF Research Database (Denmark)

    Flachs, Esben Meulengracht; Sørensen, Jan; Bønløkke, Jacob

    2013-01-01

    Objective. To explore how three different assumptions on demographics affect the health impact of Danish emitted air pollution in Denmark from 2005 to 2030, with health impact modeled from 2005 to 2050. Methods. Modeled air pollution from Danish sources was used as exposure in a newly developed......) a static year 2005 population, (2) morbidity and mortality fixed at the year 2005 level, or (3) an expected development. Results. The health impact of air pollution was estimated at 672,000, 290,000, and 280,000 lost life years depending on demographic assumptions and the corresponding social costs at 430.......4 M€, 317.5 M€, and 261.6 M€ through the modeled years 2005–2050. Conclusion. The modeled health impact of air pollution differed widely with the demographic assumptions, and thus demographics and assumptions on demographics played a key role in making health impact assessments on air pollution....

  11. Population Dynamics and Air Pollution

    DEFF Research Database (Denmark)

    Flachs, Esben Meulengracht; Sørensen, Jan; Bønløkke, Jacob

    2013-01-01

    Objective. To explore how three different assumptions on demographics affect the health impact of Danish emitted air pollution in Denmark from 2005 to 2030, with health impact modeled from 2005 to 2050. Methods. Modeled air pollution from Danish sources was used as exposure in a newly developed......) a static year 2005 population, (2) morbidity and mortality fixed at the year 2005 level, or (3) an expected development. Results. The health impact of air pollution was estimated at 672,000, 290,000, and 280,000 lost life years depending on demographic assumptions and the corresponding social costs at 430.......4 M€, 317.5 M€, and 261.6 M€ through the modeled years 2005–2050. Conclusion. The modeled health impact of air pollution differed widely with the demographic assumptions, and thus demographics and assumptions on demographics played a key role in making health impact assessments on air pollution....

  12. Curating Transient Population in Urban Dynamics System

    CERN Document Server

    Thakur, Gautam S; Stewart, Robert N; Urban, Marie L; Bhaduri, Budhendra L

    2016-01-01

    For past several decades, research efforts in population modelling has proven its efficacy in understanding the basic information about residential and commercial areas, as well as for the purposes of planning, development and improvement of the community as an eco-system. More or less, such efforts assume static nature of population distribution, in turn limited by the current ability to capture the dynamics of population change at a finer resolution of space and time. Fast forward today, more and more people are becoming mobile, traveling across borders impacting the nuts and bolts of our urban fabric. Unfortunately, our current efforts are being surpassed by the need to capture such transient population. It is becoming imperative to identify and define them, as well as measure their dynamics and interconnectedness. In this work, we intend to research urban population mobility patterns, gauge their transient nature, and extend our knowledge of their visited locations. We plan to achieve this by designing an...

  13. Population dynamical responses to climate change

    DEFF Research Database (Denmark)

    Forchhammer, Mads; Schmidt, Niels Martin; Høye, Toke Thomas

    2008-01-01

    it is well established that climatic as well as biological factors, in concert, form the mechanistic basis for our understanding of how populations develop over time and across space. Although this seemingly suggests simplicity, the climate-biology dichotomy of population dynamics embraces...... a bewildering number of interactions. For example, individuals within a population may compete for space and other resources and, being embedded in an ecosystem, individuals in any population may also interact with individuals of competing species as well as those from adjacent trophic levels. In principal...

  14. Detection, Diversity, and Population Dynamics of Waterborne Phytophthora ramorum Populations.

    Science.gov (United States)

    Eyre, C A; Garbelotto, M

    2015-01-01

    Sudden oak death, the tree disease caused by Phytophthora ramorum, has significant environmental and economic impacts on natural forests on the U.S. west coast, plantations in the United Kingdom, and in the worldwide nursery trade. Stream baiting is vital for monitoring and early detection of the pathogen in high-risk areas and is performed routinely; however, little is known about the nature of water-borne P. ramorum populations. Two drainages in an infested California forest were monitored intensively using stream-baiting for 2 years between 2009 and 2011. Pathogen presence was determined both by isolation and polymerase chain reaction (PCR) from symptomatic bait leaves. Isolates were analyzed using simple sequence repeats to study population dynamics and genetic structure through time. Isolation was successful primarily only during spring conditions, while PCR extended the period of pathogen detection to most of the year. Water populations were extremely diverse, and changed between seasons and years. A few abundant genotypes dominated the water during conditions considered optimal for aerial populations, and matched those dominant in aerial populations. Temporal patterns of genotypic diversification and evenness were identical among aerial, soil, and water populations, indicating that all three substrates are part of the same epidemiological cycle, strongly influenced by rainfall and sporulation on leaves. However, there was structuring between substrates, likely arising due to reduced selection pressure in the water. Additionally, water populations showed wholesale mixing of genotypes without the evident spatial autocorrelation present in leaf and soil populations.

  15. Population dynamics in an intermittent refuge

    Science.gov (United States)

    Colombo, E. H.; Anteneodo, C.

    2016-10-01

    Population dynamics is constrained by the environment, which needs to obey certain conditions to support population growth. We consider a standard model for the evolution of a single species population density, which includes reproduction, competition for resources, and spatial spreading, while subject to an external harmful effect. The habitat is spatially heterogeneous, there existing a refuge where the population can be protected. Temporal variability is introduced by the intermittent character of the refuge. This scenario can apply to a wide range of situations, from a laboratory setting where bacteria can be protected by a blinking mask from ultraviolet radiation, to large-scale ecosystems, like a marine reserve where there can be seasonal fishing prohibitions. Using analytical and numerical tools, we investigate the asymptotic behavior of the total population as a function of the size and characteristic time scales of the refuge. We obtain expressions for the minimal size required for population survival, in the slow and fast time scale limits.

  16. Dispersive models describing mosquitoes’ population dynamics

    Science.gov (United States)

    Yamashita, W. M. S.; Takahashi, L. T.; Chapiro, G.

    2016-08-01

    The global incidences of dengue and, more recently, zica virus have increased the interest in studying and understanding the mosquito population dynamics. Understanding this dynamics is important for public health in countries where climatic and environmental conditions are favorable for the propagation of these diseases. This work is based on the study of nonlinear mathematical models dealing with the life cycle of the dengue mosquito using partial differential equations. We investigate the existence of traveling wave solutions using semi-analytical method combining dynamical systems techniques and numerical integration. Obtained solutions are validated through numerical simulations using finite difference schemes.

  17. Towards a Population Dynamics Theory for Evolutionary Computing: Learning from Biological Population Dynamics in Nature

    Science.gov (United States)

    Ma, Zhanshan (Sam)

    In evolutionary computing (EC), population size is one of the critical parameters that a researcher has to deal with. Hence, it was no surprise that the pioneers of EC, such as De Jong (1975) and Holland (1975), had already studied the population sizing from the very beginning of EC. What is perhaps surprising is that more than three decades later, we still largely depend on the experience or ad-hoc trial-and-error approach to set the population size. For example, in a recent monograph, Eiben and Smith (2003) indicated: "In almost all EC applications, the population size is constant and does not change during the evolutionary search." Despite enormous research on this issue in recent years, we still lack a well accepted theory for population sizing. In this paper, I propose to develop a population dynamics theory forEC with the inspiration from the population dynamics theory of biological populations in nature. Essentially, the EC population is considered as a dynamic system over time (generations) and space (search space or fitness landscape), similar to the spatial and temporal dynamics of biological populations in nature. With this conceptual mapping, I propose to 'transplant' the biological population dynamics theory to EC via three steps: (i) experimentally test the feasibility—whether or not emulating natural population dynamics improves the EC performance; (ii) comparatively study the underlying mechanisms—why there are improvements, primarily via statistical modeling analysis; (iii) conduct theoretical analysis with theoretical models such as percolation theory and extended evolutionary game theory that are generally applicable to both EC and natural populations. This article is a summary of a series of studies we have performed to achieve the general goal [27][30]-[32]. In the following, I start with an extremely brief introduction on the theory and models of natural population dynamics (Sections 1 & 2). In Sections 4 to 6, I briefly discuss three

  18. Extinction rate fragility in population dynamics.

    Science.gov (United States)

    Khasin, M; Dykman, M I

    2009-08-01

    Population extinction is of central interest for population dynamics. It may occur from a large rare fluctuation. We find that, in contrast to related large-fluctuation effects like noise-induced interstate switching, quite generally extinction rates in multipopulation systems display fragility, where the height of the effective barrier to be overcome in the fluctuation depends on the system parameters nonanalytically. We show that one of the best-known models of epidemiology, the susceptible-infectious-susceptible model, is fragile to total population fluctuations.

  19. Breastfeeding gains popularity in Honduras.

    Science.gov (United States)

    Townsend, S

    1992-10-01

    In 1982, a breast feeding support program (PROALMA) first operated in 3 large public hospitals and a large health center in Tegucigalpa and San Pedro Sula, Honduras. It trained health workers about the benefits of breast feeding and lactation management and developed hospital breast feeding policies and practices, e.g., creation of a milk bank for premature newborns. It even convinced hospitals to stop free distribution of infant formula and bottles. In fact, annual expenditures for infant formula at the Social Security Hospital in San Pedro Sula fell from US$ 40,000 to 6000 in 1 year and to 0 by 1990. Hospital practices which were not conducive to breast feeding included separation of newborns from mothers and giving newborns sugar water as their first food. In fact, 69% of mothers at Tegucigalpa hospitals said hospital staff gave their newborns breast milk substitutes within 24 hours of birth. The program began a rooming-in system which made it easier for mothers to initiate early, frequent, and on-demand breast feeding. PROALMA staff were in the maternity wards daily to provide breast feeding counseling. At the end of 3 years, 98% of women delivering at Tegucigalpa hospitals breast fed their infants. The project eventually expanded to hospitals nationwide. Between 1981 and 1988, breast feeding rose from 80% to 93% in cities and from 95% to 98% in rural areas. Further, the median duration of breast feeding increased from 4 months to 10 months (1982-1987) in cities. Yet, just 6% of mothers exclusively breast fed their 3-4 month old infants in 1987. In addition, only 28% exclusively breast fed before introducing the bottle. Staff attitude improved as evidenced by an increase in the percentage of workers promoting breast feeding at birth (37-86% during 1982-1986). PROALMA concluded that increased efforts to promote exclusive breast feeding are needed.

  20. West Indian Sojourners in Guatemala and Honduras

    Directory of Open Access Journals (Sweden)

    Ronald N. Harpelle

    2012-12-01

    Full Text Available Review of: Race, Nation, and West Indian Immigration to Honduras, 1890-1940. Glenn A. Chambers. Baton Rouge: Louisiana State University Press, 2010. xii +202 pp. (Cloth US$ 35.00Black Labor Migration in Caribbean Guatemala, 1882-1923. Frederick Douglass Opie. Gainesville: University Press of Florida, 2009. 145 pp. (Cloth US$ 65.00

  1. Book Review: The Snakes of Honduras

    Directory of Open Access Journals (Sweden)

    Hussam Zaher

    2011-07-01

    Full Text Available Book review: McCranie, J. R. 2011. The Snakes of Honduras – Systematics, Distribution, and Conservation. Contributions to Herpetology, Volume 26. Society for the Study of Amphibians andReptiles, Thomson-Shore, Inc., Michigan. 724 pages, 65 figures, 23 tables, 20 color plates.

  2. Doing Business Economy Profile 2015 : Honduras

    OpenAIRE

    2014-01-01

    This economy profile for Doing Business 2015 presents the 11 Doing Business indicators for Honduras. To allow for useful comparison, the profile also provides data for other selected economies (comparator economies) for each indicator. Doing Business 2015 is the 12th edition in a series of annual reports measuring the regulations that enhance business activity and those that constrain it. ...

  3. Salmonella in beef and produce from honduras.

    Science.gov (United States)

    Maradiaga, Martha; Miller, Mark F; Thompson, Leslie; Pond, Ansen; Gragg, Sara E; Echeverry, Alejandro; Garcia, Lyda G; Loneragan, Guy H; Brashears, Mindy M

    2015-03-01

    Salmonella continues to cause a considerable number of foodborne illnesses worldwide. The sources of outbreaks include contaminated meat and produce. The purpose of this study was to establish an initial investigation of the burden of Salmonella in produce and beef from Honduras by sampling retail markets and abattoirs. Retail produce samples (cantaloupes, cilantro, cucumbers, leafy greens, peppers, and tomatoes; n = 573) were purchased in three major cities of Honduras, and retail whole-muscle beef (n = 555) samples were also purchased in four major cities. Additionally, both hide and beef carcass (n = 141) samples were collected from two Honduran abattoirs. Whole-muscle beef samples were obtained using a sponge hydrated with buffered peptone water, and 10 ml of the buffered peptone water rinsate of each produce sample was collected with a dry sponge and placed in a bag to be transported back to the United States. Salmonella was detected using a commercially available, closeplatform PCR system, and positive samples were subjected to culture on selective media to obtain isolates. Overall, the prevalence of Salmonella-positive samples, based on PCR detection in Honduras (n = 555) retail beef was 10.1% (95% confidence interval = 7.8, 12.9), whereas 7.8% (n = 141) of beef carcass and hides samples were positive in both beef plants. The overall Salmonella prevalence for all produce samples (n = 573) collected was 2.1% (95% confidence interval = 1.2, 3.6). The most common serotypes identified in Honduras were Salmonella Typhimurium followed by Derby. These results provide an indication of Salmonella contamination of beef and produce in Honduras. Developing a Salmonella baseline for Latin America through an initial investigation like the one presented here contributes to a broader global understanding of the potential exposure through food, thus providing insight into the needs for control strategies.

  4. Population mixture model for nonlinear telomere dynamics

    Science.gov (United States)

    Itzkovitz, Shalev; Shlush, Liran I.; Gluck, Dan; Skorecki, Karl

    2008-12-01

    Telomeres are DNA repeats protecting chromosomal ends which shorten with each cell division, eventually leading to cessation of cell growth. We present a population mixture model that predicts an exponential decrease in telomere length with time. We analytically solve the dynamics of the telomere length distribution. The model provides an excellent fit to available telomere data and accounts for the previously unexplained observation of telomere elongation following stress and bone marrow transplantation, thereby providing insight into the nature of the telomere clock.

  5. Dynamical quorum sensing: Population density encoded in cellular dynamics

    Science.gov (United States)

    De Monte, Silvia; d'Ovidio, Francesco; Danø, Sune; Sørensen, Preben Graae

    2007-01-01

    Mutual synchronization by exchange of chemicals is a mechanism for the emergence of collective dynamics in cellular populations. General theories exist on the transition to coherence, but no quantitative, experimental demonstration has been given. Here, we present a modeling and experimental analysis of cell-density-dependent glycolytic oscillations in yeast. We study the disappearance of oscillations at low cell density and show that this phenomenon occurs synchronously in all cells and not by desynchronization, as previously expected. This study identifies a general scenario for the emergence of collective cellular oscillations and suggests a quorum-sensing mechanism by which the cell density information is encoded in the intracellular dynamical state. PMID:18003917

  6. Galactic civilizations - Population dynamics and interstellar diffusion

    Science.gov (United States)

    Newman, W. I.; Sagan, C.

    1981-01-01

    A model is developed of the interstellar diffusion of galactic civilizations which takes into account the population dynamics of such civilizations. The problem is formulated in terms of potential theory, with a family of nonlinear partial differential and difference equations specifying population growth and diffusion for an organism with advantageous genes that undergoes random dispersal while increasing in population locally, and a population at zero population growth. In the case of nonlinear diffusion with growth and saturation, it is found that the colonization wavefront from the nearest independently arisen galactic civilization can have reached the earth only if its lifetime exceeds 2.6 million years, or 20 million years if discretization can be neglected. For zero population growth, the corresponding lifetime is 13 billion years. It is concluded that the earth is uncolonized not because interstellar spacefaring civilizations are rare, but because there are too many worlds to be colonized in the plausible colonization lifetime of nearby civilizations, and that there exist no very old galactic civilizations with a consistent policy of the conquest of inhabited worlds.

  7. A dynamic network in a dynamic population: asymptotic properties

    CERN Document Server

    Britton, Tom; Turova, Tatyana

    2011-01-01

    We derive asymptotic properties for a stochastic dynamic network model in a stochastic dynamic population. In the model, nodes give birth to new nodes until they die, each node being equipped with a social index given at birth. During the life of a node it creates edges to other nodes, nodes with high social index at higher rate, and edges disappear randomly in time. For this model we derive criterion for when a giant connected component exists after the process has evolved for a long period of time, assuming the node population grows to infinity. We also obtain an explicit expression for the degree correlation $\\rho$ (of neighbouring nodes) which shows that $\\rho$ is always positive irrespective of parameter values in one of the two treated submodels, and may be either positive or negative in the other model, depending on the parameters.

  8. The herpetofauna of the cloud forests of Honduras

    OpenAIRE

    Wilson, Larry David; McCranie, James R.

    2010-01-01

    The cloud forest amphibians and reptiles constitute the most important herpetofaunal segment in Honduras, due to the prevalence of endemic and Nuclear Middle American-restricted species. This segment, however, is subject to severe environmental threats due to the actions of humans. Of the 334 species of amphibians and reptiles currently known from Honduras, 122 are known to be distributed in cloud forest habitats. Cloud forest habitats are found throughout the mountainous interior of Honduras...

  9. The herpetofauna of the cloud forests of Honduras

    OpenAIRE

    Wilson, Larry David; James R. McCranie

    2010-01-01

    The cloud forest amphibians and reptiles constitute the most important herpetofaunal segment in Honduras, due to the prevalence of endemic and Nuclear Middle American-restricted species. This segment, however, is subject to severe environmental threats due to the actions of humans. Of the 334 species of amphibians and reptiles currently known from Honduras, 122 are known to be distributed in cloud forest habitats. Cloud forest habitats are found throughout the mountainous interior of Honduras...

  10. Population Code Dynamics in Categorical Perception.

    Science.gov (United States)

    Tajima, Chihiro I; Tajima, Satohiro; Koida, Kowa; Komatsu, Hidehiko; Aihara, Kazuyuki; Suzuki, Hideyuki

    2016-03-03

    Categorical perception is a ubiquitous function in sensory information processing, and is reported to have important influences on the recognition of presented and/or memorized stimuli. However, such complex interactions among categorical perception and other aspects of sensory processing have not been explained well in a unified manner. Here, we propose a recurrent neural network model to process categorical information of stimuli, which approximately realizes a hierarchical Bayesian estimation on stimuli. The model accounts for a wide variety of neurophysiological and cognitive phenomena in a consistent framework. In particular, the reported complexity of categorical effects, including (i) task-dependent modulation of neural response, (ii) clustering of neural population representation, (iii) temporal evolution of perceptual color memory, and (iv) a non-uniform discrimination threshold, are explained as different aspects of a single model. Moreover, we directly examine key model behaviors in the monkey visual cortex by analyzing neural population dynamics during categorization and discrimination of color stimuli. We find that the categorical task causes temporally-evolving biases in the neuronal population representations toward the focal colors, which supports the proposed model. These results suggest that categorical perception can be achieved by recurrent neural dynamics that approximates optimal probabilistic inference in the changing environment.

  11. A new Nototriton (Caudata: Plethodontidae) from Parque Nacional Montaña de Botaderos in northeastern Honduras.

    Science.gov (United States)

    Townsend, Josiah H; Medina-flores, Melissa; Reyes-Calderón, Onán; Austin, James D

    2013-01-01

    The highlands of northeastern Honduras remain under-characterized in terms of biological diversity, as exemplified by the regularity of new amphibian and reptile taxa discoveries. Following the recent description of a new species of Nototriton from the Sierra de Agalta in northeastern Honduras, we report the discovery of a second new species of Nototriton from the nearby Parque Nacional Montaña de Botaderos. This new taxon, Nototriton mime sp. nov., is distinguished from other Nototriton by its distinctive pale brown dorsal coloration in adult males, relatively large nares, a relatively broad head, mitochondrial sequence divergence, and phylogenetic relationships, and is geographically isolated from other populations of Nototriton.

  12. Nonlocal Crowd Dynamics Models for several Populations

    CERN Document Server

    Colombo, Rinaldo M

    2011-01-01

    This paper develops the basic analytical theory related to some recently introduced crowd dynamics models. Where well posedness was known only locally in time, it is here extended to all of $\\reali^+$. The results on the stability with respect to the equations are improved. Moreover, here the case of several populations is considered, obtaining the well posedness of systems of multi-D non-local conservation laws. The basic analytical tools are provided by the classical Kruzkov theory of scalar conservation laws in several space dimensions.

  13. NONLOCAL CROWD DYNAMICS MODELS FOR SEVERAL POPULATIONS

    Institute of Scientific and Technical Information of China (English)

    Rinaldo M. Colombo; Magali Lécureux-Mercier

    2012-01-01

    This paper develops the basic analytical theory related to some recently introduced crowd dynamics models.Where well posedness was known only locally in time,it is here extended to all of R+.The results on the stability with respect to the equations are improved.Moreover,here the case of several populations is considered,obtaining the well posedness of systems of multi-D non-local conservation laws.The basic analytical tools are provided by the classical Kru(z)kov theory of scalar conservation laws in several space dimensions.

  14. A population dynamics approach to biological aging

    Science.gov (United States)

    de Almeida, R. M. C.

    A dynamical model for aging in biological population is discussed where asexual reproduction is considered. The maximum life span is inherited from parent to offspring with some random mutations described by a transition matrix, and the fertile period begins at a defined age R. The intra species competition is modeled through a Verhulst-like factor. Discrete time evolution equations are iterated and the transient and asymptotic solutions are obtained. When only bad mutations are taken into account, the stationary solutions are obtained analytically. The results are applied to the Penna model.

  15. On the contradiction between the statistical parameters of population dynamics

    OpenAIRE

    Korosov Andrey

    2012-01-01

    A model simulating the dynamics of the field vole (Microtus agrestis) numerosity during one year was built. The purpose of modeling was to reproduce the values of population characteristics, averaged over a long period of field observations. It was found that long-term average population characteristics can not be observed in any one year of simulated population life. A model population with an average long-term dynamics of age structure can not sustain long-term population dynamics. Long-ter...

  16. [Population dynamics and development in the Caribbean].

    Science.gov (United States)

    Boland, B

    1995-12-01

    The impact is examined of socioeconomic factors on Caribbean population dynamics. This work begins by describing the socioeconomic context of the late 1980s and early 1990s, under the influence of the economic changes and crises of the 1980s. The small size, openness, dependency, and lack of diversification of the Caribbean economies have made them vulnerable to external pressures. The Bahamas and Belize had economic growth rates exceeding 5% annually during 1981-90, but most of the countries had low or negative growth. Unemployment, poverty, the structural adjustment measures adopted in the mid-1980s, and declines in social spending exacerbated general economic conditions. In broad terms, the population situation of the Caribbean is marked by diversity of sizes and growth rates. A few countries oriented toward services and tourism had demographic growth rates exceeding 3%, while at least 7 had almost no growth or negative growth. Population growth rates reflected different combinations of natural increase and migration. Crude death rates ranged from around 5/1000 to 11/1000, except in Haiti, and all countries of the region except Haiti had life expectancies of 70 years or higher. Despite fertility decline, the average crude birth rate was still relatively high at 26/1000, and the rate of natural increase was 1.8% annually for the region. Nearly half of the regional population was under 15 or over 65 years old. The body of this work provides greater detail on mortality patterns, variations by sex, infant mortality, causes of death, and implications for policy. The discussion of fertility includes general patterns and trends, age specific fertility rates, contraceptive prevalence, levels of adolescent fertility and age factors in adolescent sexual behavior, characteristics of adolescent unions, contraceptive usage, health and social consequences of adolescent childbearing, and the search for solutions. The final section describes the magnitude and causes of

  17. Dimensions of Child Sexual Abuse before Age 15 in Three Central American Countries: Honduras, El Salvador, and Guatemala

    Science.gov (United States)

    Speizer, Ilene S.; Goodwin, Mary; Whittle, Lisa; Clyde, Maureen; Rogers, Jennifer

    2008-01-01

    Objective: The prevalence of sexual abuse during childhood or adolescence varies depending on the definitions and age categories used. This study examines the first national, population-based data available on child sexual abuse that occurs before age 15 in three countries: El Salvador, Guatemala, and Honduras. This study uses comparable…

  18. Dimensions of Child Sexual Abuse before Age 15 in Three Central American Countries: Honduras, El Salvador, and Guatemala

    Science.gov (United States)

    Speizer, Ilene S.; Goodwin, Mary; Whittle, Lisa; Clyde, Maureen; Rogers, Jennifer

    2008-01-01

    Objective: The prevalence of sexual abuse during childhood or adolescence varies depending on the definitions and age categories used. This study examines the first national, population-based data available on child sexual abuse that occurs before age 15 in three countries: El Salvador, Guatemala, and Honduras. This study uses comparable…

  19. The conservation status of the herpetofauna of Honduras.

    Science.gov (United States)

    Wilson, Larry David; McCranie, James R

    2004-01-01

    The conservation status of the members of the Honduran herpetofauna is discussed. Based on current and projected future human population growth, it is posited that the entire herpetofauna is endangered. The known herpetofauna of Honduras currently consists of 334 species, including 117 amphibians and 217 reptiles (including six marine reptiles, which are not discussed in this paper). The greatest number of species occur at low and moderate elevations in lowland and/or mesic forest formations, in the Northern and Southern Cordilleras of the Serranía, and the ecophysiographic areas of the Caribbean coastal plain and foothills. Slightly more than one-third of the herpetofauna consists of endemic species or those otherwise restricted to Nuclear Middle America. Honduras is an area severely affected by amphibian population decline, with close to one-half of the amphibian fauna threatened, endangered, or extinct. The principal threats to the survival of members of the herpetofauna are uncontrolled human population growth and its corollaries, habitat alteration and destruction, pollution, pest and predator control, overhunting, and overexploitation. No Honduran amphibians or reptiles are entirely free of human impact. A gauge is used to estimate environmental vulnerability of amphibian species, using measures of extent of geographic range, extent of ecological distribution, and degree of specialization of reproductive mode. A similar gauge is developed for reptiles, using the first two measures for amphibian vulnerability, and a third scale for the degree of human persecution. Based on these gauges, amphibians and reptiles show an actual range of Environmental Vulnerability Scores (EVS) almost as broad as the theoretical range. Based on the actual EVS, both amphibian and reptilian species are divided into three categories of low, medium, and high vulnerability. There are 24 low vulnerability amphibians and 47 reptiles, 43 medium vulnerability amphibians and 111 reptiles

  20. Long-term dynamics of Typha populations

    Science.gov (United States)

    Grace, J.B.; Wetzel, R.G.

    1998-01-01

    The zonation of Typha populations in an experimental pond in Michigan was re-examined 15 years after the original sampling to gain insight into the long-term dynamics. Current distributions of Typha populations were also examined in additional experimental ponds at the site that have been maintained for 23 years. The zonation between T. latifolia and T. angustifolia in the previously studied pond 15 years after the initial sampling revealed that the density and distribution of shoots had not changed significantly. Thus, it appears that previously reported results (based on 7- year old populations) have remained consistent over time. Additional insight into the interaction between these two taxa was sought by comparing mixed and monoculture stands in five experimental ponds that have remained undisturbed for their 23-year history. The maximum depth of T. latifolia, the shallow- water species, was not significantly reduced when growing in the presence of the more flood tolerant T. angustifolia. In contrast, the minimum depth of T. angustifolia was reduced from 0 to 37 cm when in the presence of T. latifolia. When total populations were compared between monoculture and mixed stands, the average density of T. angustifolia shoots was 59.4 percent lower in mixed stands while the density of T. latifolia was 32 percent lower, with T. angustifolia most affected at shallow depths (reduced by 92 percent) and T. latifolia most affected at the deepest depths (reduced by 60 percent). These long-term observations indicate that competitive displacement between Typha taxa has remained stable over time.

  1. Population dynamics of species-rich ecosystems: the mixture of matrix population models approach

    DEFF Research Database (Denmark)

    Mortier, Frédéric; Rossi, Vivien; Guillot, Gilles;

    2013-01-01

    Matrix population models are widely used to predict population dynamics, but when applied to species-rich ecosystems with many rare species, the small population sample sizes hinder a good fit of species-specific models. This issue can be overcome by assigning species to groups to increase the size...... species with similar population dynamics....

  2. Biotic Population Dynamics: Creative Biotic Patterns

    Science.gov (United States)

    Sabelli, Hector; Kovacevic, Lazar

    We present empirical studies and computer models of population dynamics that demonstrate creative features and we speculate that these creative processes may underline evolution. Changes in population size of lynx, muskrat, beaver, salmon, and fox display diversification, episodic changes in pattern, novelty, and evidence for nonrandom causation. These features of creativity characterize bios, and rule out random, periodic, chaotic, and random walk patterns. Biotic patterns are also demonstrated in time series generated with multi-agent predator-prey simulations. These results indicate that evolutionary processes are continually operating. In contrast to standard evolutionary theory (random variation, competition for scarce resources, selection by survival of the fittest, and directionless, meaningless evolution), we propose that biological evolution is a creative development from simple to complex in which (1) causal actions generate biological variation; (2) bipolar feedback (synergy and antagonism, abundance and scarcity) generates information (diversification, novelty and complexity); (3) connections (of molecules, genes, species) construct systems in which simple processes have priority for survival but complex processes acquire supremacy.

  3. Honduras y las relaciones internacionales. 1850 - 1900

    OpenAIRE

    Zepeda Ordoñez, Ismael

    2016-01-01

    El presente ensayo es una aproximación por explicar la política exterior de Honduras entre 1850- 1900,como expresión en la evolución del Estado nacional, que nos permita comprender su comportamiento enlas relaciones internacionales. Analizar sus posiciones, intereses y contradicciones, su papel en el contextocentroamericano, y a la luz de las Instrucciones otorgadas a los funcionarios diplomáticos determinar sugrado de independencia. Entiéndase Instrucciones al conjunto de recomendaciones, fa...

  4. Perturbation analysis of transient population dynamics using matrix projection models

    DEFF Research Database (Denmark)

    Stott, Iain

    2016-01-01

    Non-stable populations exhibit short-term transient dynamics: size, growth and structure that are unlike predicted long-term asymptotic stable, stationary or equilibrium dynamics. Understanding transient dynamics of non-stable populations is important for designing effective population management...... strategies, predicting the responses of populations to environmental change or disturbance, and understanding population processes and life-history evolution in variable environments. Transient perturbation analyses are vital tools for achieving these aims. They assess how transient dynamics are affected...... of model being analysed, the perturbation structure, the population response of interest, nonlinear response to perturbation, standardization for asymptotic dynamics, the initial population structure, and the time frame of interest. I discuss these with reference to the application of transient...

  5. Dynamics of genome rearrangement in bacterial populations.

    Directory of Open Access Journals (Sweden)

    Aaron E Darling

    represent the first characterization of genome arrangement evolution in a bacterial population evolving outside laboratory conditions. Insight into the process of genomic rearrangement may further the understanding of pathogen population dynamics and selection on the architecture of circular bacterial chromosomes.

  6. Population dynamic theory of size-dependent cannibalism

    NARCIS (Netherlands)

    Claessen, D.; de Roos, A.M.; Persson, L.

    2004-01-01

    Cannibalism is characterized by four aspects: killing victims, gaining energy from victims, size-dependent interactions and intraspecific competition. In this review of mathematical models of cannibalistic populations, we relate the predicted population dynamic consequences of cannibalism to its fou

  7. Population dynamic theory of size-dependent cannibalism

    NARCIS (Netherlands)

    Claessen, D.; de Roos, A.M.; Persson, L.

    2004-01-01

    Cannibalism is characterized by four aspects: killing victims, gaining energy from victims, size-dependent interactions and intraspecific competition. In this review of mathematical models of cannibalistic populations, we relate the predicted population dynamic consequences of cannibalism to its fou

  8. Population dynamics in biological treatment process. ; Population dynamics of bacteria for biological phosphorus removal. Population dynamics to kankyo joka. ; Datsurin kin gun no population dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Okada, M. (Hiroshima Univ., Hiroshima (Japan). Faculty of Engineering)

    1992-09-10

    The microbial industry can easily cultivate only the specific microorganism by introducing the closed reaction system and the sterile operation. When the superior bacteria is selected or it is created by the gene manipulation, therefore, it is not so much difficult that it is utilized for production. Since the water treatment is an open reaction system many microorganisms can join, however, it becomes to be important that how the necessary microorganisms, for example, the dephosphorylation bacteria etc. out of them are let fixed in the reaction system, and win in a competition with the other microorganisms, and in addition, are let display their functions stably for a long period. In this regard, in this paper, concerning to the issues that whether the dephosphorylation bacteria exists or not, how the behavior of dephosphorylation bacteria in the activated sludge should be clarified, what kind of behavior the dephosphorylation bacteria shows in the dephosphorylation activated sludge and so forth, grasping the population dynamics of microorganism, and furthermore, including the methodology to control it, is outlined. 31 refs., 2 figs., 1 tab.

  9. Nesting Ecology of Hawksbill Sea Turtles (Eretmochelys imbricata) on Utila, Honduras

    Science.gov (United States)

    Damazo, Lindsey Renee Eggers

    The hawksbill sea turtle (Eretmochelys imbricata) has a circumtropical distribution and plays an important role in maintaining the health of coral reefs. Unfortunately, hawksbill populations have been decimated, and estimated numbers in the Caribbean are less than 10% of populations a century ago. The hawksbill is considered Critically Endangered, and researchers are coordinating worldwide efforts to protect this species. One country where we lack knowledge regarding hawksbills is Honduras. This study aimed to increase our understanding of hawksbill nesting ecology in Caribbean Honduras. Characteristics of hawksbill nesting activity and a nesting beach on the island of Utila were elucidated using satellite telemetry, beach profiling, vegetation surveys, beach monitoring, and nest temperature profiles. We affixed satellite transmitters to two nesting hawksbills, and found the turtles migrated to different countries. One turtle traveled 403 km to a bay in Mexico, and the other traveled 181 km to a Marine Protected Area off Belize. This study presents the first description of hawksbill migration routes from Honduras, facilitating protection efforts for turtles that traverse international waters. To investigate nesting beach and turtle characteristics, we conducted beach monitoring during the 2012 nesting season. Nesting turtle carapace sizes were similar to worldwide values, but hatchlings were heavier. To measure nest temperatures, we placed thermocouple data loggers in four nests and four pseudo-nests. Data suggested metabolic heating may be maintaining nest temperatures above the pivotal temperature. However, large temperature fluctuations corresponding to rainfall from Hurricane Ernesto (as determined using a time series cross-correlation analysis) make it difficult to predict sex ratios, and underscore the impact stochastic events can have on nest temperatures. We created topographic and substrate profiles of the beach, and found it was 475 m long, yet hawksbills

  10. Effects of an invasive plant on population dynamics in toads.

    Science.gov (United States)

    Greenberg, Daniel A; Green, David M

    2013-10-01

    When populations decline in response to unfavorable environmental change, the dynamics of their population growth shift. In populations that normally exhibit high levels of variation in recruitment and abundance, as do many amphibians, declines may be difficult to identify from natural fluctuations in abundance. However, the onset of declines may be evident from changes in population growth rate in sufficiently long time series of population data. With data from 23 years of study of a population of Fowler's toad (Anaxyrus [ = Bufo] fowleri) at Long Point, Ontario (1989-2011), we sought to identify such a shift in dynamics. We tested for trends in abundance to detect a change point in population dynamics and then tested among competing population models to identify associated intrinsic and extrinsic factors. The most informative models of population growth included terms for toad abundance and the extent of an invasive marsh plant, the common reed (Phragmites australis), throughout the toads' marshland breeding areas. Our results showed density-dependent growth in the toad population from 1989 through 2002. After 2002, however, we found progressive population decline in the toads associated with the spread of common reeds and consequent loss of toad breeding habitat. This resulted in reduced recruitment and population growth despite the lack of significant loss of adult habitat. Our results underscore the value of using long-term time series to identify shifts in population dynamics coincident with the advent of population decline. © 2013 Society for Conservation Biology.

  11. Microbial population dynamics by digital in-line holographic microscopy

    Science.gov (United States)

    Frentz, Zak; Kuehn, Seppe; Hekstra, Doeke; Leibler, Stanislas

    2010-08-01

    Measurements of population dynamics are ubiquitous in experiments with microorganisms. Studies with microbes elucidating adaptation, selection, and competition rely on measurements of changing populations in time. Despite this importance, quantitative methods for measuring population dynamics microscopically, with high time resolution, across many replicates remain limited. Here we present a new noninvasive method to precisely measure microbial spatiotemporal population dynamics based on digital in-line holographic (DIH) microscopy. Our inexpensive, replicate DIH microscopes imaged hundreds of swimming algae in three dimensions within a volume of several microliters on a time scale of minutes over periods of weeks.

  12. Microbial population dynamics by digital in-line holographic microscopy.

    Science.gov (United States)

    Frentz, Zak; Kuehn, Seppe; Hekstra, Doeke; Leibler, Stanislas

    2010-08-01

    Measurements of population dynamics are ubiquitous in experiments with microorganisms. Studies with microbes elucidating adaptation, selection, and competition rely on measurements of changing populations in time. Despite this importance, quantitative methods for measuring population dynamics microscopically, with high time resolution, across many replicates remain limited. Here we present a new noninvasive method to precisely measure microbial spatiotemporal population dynamics based on digital in-line holographic (DIH) microscopy. Our inexpensive, replicate DIH microscopes imaged hundreds of swimming algae in three dimensions within a volume of several microliters on a time scale of minutes over periods of weeks.

  13. Honduras’ National Security Strategy To Combat Terrorism

    Science.gov (United States)

    2006-12-01

    homesec/docs/nonprof/nps12-011504-01.pdf (accessed February 8, 2006). 5 Honduras, Secretaria de Defensa Nacional, ed., Honduras: Libro De La Defensa...trafficking, but they 51El Heraldo, "Aumenta Robo De Autos," sec. Economia , March 16, 2006. http...El Heraldo. "Aumenta Robo De Autos." March 16, 2006, sec. Economia . http://www.elheraldo.hn/nota.php?nid=47461&sec=9&fecha=2006-03-16 (accessed

  14. Honduras: Political and Economic Situation and U.S. Relations

    Science.gov (United States)

    2006-10-13

    important for the Honduran economy, but nontraditional sectors, such as shrimp farming and the maquiladora , or export-processing industry, have grown...with U.S. apparel companies for duty-free entry into the United States of certain apparel products assembled in Honduras. As a result, maquiladoras ...2000 (CBTPA), which provides Caribbean Basin nations with NAFTA-like preferential tariff treatment, further boosted Honduran maquiladoras . Honduras

  15. Evolutionary dynamics with fluctuating population sizes and strong mutualism

    Science.gov (United States)

    Chotibut, Thiparat; Nelson, David R.

    2015-08-01

    Game theory ideas provide a useful framework for studying evolutionary dynamics in a well-mixed environment. This approach, however, typically enforces a strictly fixed overall population size, deemphasizing natural growth processes. We study a competitive Lotka-Volterra model, with number fluctuations, that accounts for natural population growth and encompasses interaction scenarios typical of evolutionary games. We show that, in an appropriate limit, the model describes standard evolutionary games with both genetic drift and overall population size fluctuations. However, there are also regimes where a varying population size can strongly influence the evolutionary dynamics. We focus on the strong mutualism scenario and demonstrate that standard evolutionary game theory fails to describe our simulation results. We then analytically and numerically determine fixation probabilities as well as mean fixation times using matched asymptotic expansions, taking into account the population size degree of freedom. These results elucidate the interplay between population dynamics and evolutionary dynamics in well-mixed systems.

  16. Introducing Dynamic Analysis Using Malthus's Principle of Population.

    Science.gov (United States)

    Pingle, Mark

    2003-01-01

    Declares the use of dynamic models is increasing in macroeconomics. Explains how to introduce dynamic models to students whose technical skills are modest or varied. Chooses Malthus's Principle of Population as a natural context for introducing dynamic analysis because it provides a method for reviewing the mathematical tools and theoretical…

  17. Sterilization in Honduras: assessing the unmet demand.

    Science.gov (United States)

    Janowitz, B; Nunez, J A; Covington, D L; Colven, C E

    1983-10-01

    The purpose of this study was to evaluate and compare the availability of sterilization services at two hospitals in Honduras. Approximately 7,000 women who had given birth at the Hospital Materno Infantil in Tegucigalpa and the Hospital Leonardo Martinez in San Pedro Sula were asked about their desire for sterilization. Of the women who wanted to be sterilized, a considerable percentage had not been sterilized four months after they had given birth--58 percent of those who had delivered at Materno Infantil and 79 percent of those who had delivered at Leonardo Martinez. Twenty-three percent of the women who delivered at Materno Infantil and 4 percent of the women who delivered at Leonardo Martinez were sterilized before they were discharged. The difference may be attributed to the poor quality of the facilities at Leonardo Martinez.

  18. Bounds on the dynamics of sink populations with noisy immigration

    DEFF Research Database (Denmark)

    Eager, Eric Alan; Guiver, Chris; Hodgson, Dave

    2014-01-01

    Sink populations are doomed to decline to extinction in the absence of immigration. The dynamics of sink populations are not easily modelled using the standard framework of per capita rates of immigration, because numbers of immigrants are determined by extrinsic sources (for example, source...... populations, or population managers). Here we appeal to a systems and control framework to place upper and lower bounds on both the transient and future dynamics of sink populations that are subject to noisy immigration. Immigration has a number of interpretations and can fit a wide variety of models found...

  19. Synchronization Phenomena in an Array of Population Dynamic Systems

    DEFF Research Database (Denmark)

    Postnov, D.E.; Balanov, A.G.; Mosekilde, Erik

    1998-01-01

    The paper applies continuation methods to examine synchronization phenomena that can arise in a cascaded system of population dynamic models. The individual model describes a bacterial population interacting with a population of viruses that attack the cells. Coupling between the subsystems...

  20. [The effect of the new technological revolution on population dynamics].

    Science.gov (United States)

    Wu, K

    1985-01-29

    The impact of modernization on population dynamics in China is examined. The author notes that the industrialization process involves the concentration of the population in urban areas and the mechanization of agriculture. The need to redistribute the urban population from major urban areas to smaller towns is noted.

  1. Population dynamics of patella vulgata in orkney

    Science.gov (United States)

    Baxter, J. M.

    A population of Patella vulgata has been studied at Dyke-end, in Orkney. The population had a polymodal distribution, within which several year-classes were identified. Spawning occured between January and April each year and the first signs of spat settlement were recorded between August and October. Growth was suppressed over the winter months and increased during the summer, although the mature proportion of the population showed a reduction in growth rate at the onset of gonad development. Annual fluctuations in population density were attributed to spat recruitment and subsequent mortality of animals of < 30 mm lenght; little mortality of lager animals occurred.

  2. Delay driven spatiotemporal chaos in single species population dynamics models.

    Science.gov (United States)

    Jankovic, Masha; Petrovskii, Sergei; Banerjee, Malay

    2016-08-01

    Questions surrounding the prevalence of complex population dynamics form one of the central themes in ecology. Limit cycles and spatiotemporal chaos are examples that have been widely recognised theoretically, although their importance and applicability to natural populations remains debatable. The ecological processes underlying such dynamics are thought to be numerous, though there seems to be consent as to delayed density dependence being one of the main driving forces. Indeed, time delay is a common feature of many ecological systems and can significantly influence population dynamics. In general, time delays may arise from inter- and intra-specific trophic interactions or population structure, however in the context of single species populations they are linked to more intrinsic biological phenomena such as gestation or resource regeneration. In this paper, we consider theoretically the spatiotemporal dynamics of a single species population using two different mathematical formulations. Firstly, we revisit the diffusive logistic equation in which the per capita growth is a function of some specified delayed argument. We then modify the model by incorporating a spatial convolution which results in a biologically more viable integro-differential model. Using the combination of analytical and numerical techniques, we investigate the effect of time delay on pattern formation. In particular, we show that for sufficiently large values of time delay the system's dynamics are indicative to spatiotemporal chaos. The chaotic dynamics arising in the wake of a travelling population front can be preceded by either a plateau corresponding to dynamical stabilisation of the unstable equilibrium or by periodic oscillations.

  3. Role of finite populations in determining evolutionary dynamics

    Science.gov (United States)

    Ray, Tane S.; Payne, Karl A.; Moseley, L. Leo

    2008-02-01

    The connection between the finite size of an evolving population and its dynamical behavior is examined through analytical and computational studies of a simple model of evolution. The infinite population limit of the model is shown to be governed by a special case of the quasispecies equations. A flat fitness landscape yields identical results for the dynamics of infinite and finite populations. On the other hand, a monotonically increasing fitness landscape shows “epochs” in the dynamics of finite populations that become more pronounced as the rate of mutation decreases. The details of the dynamics are profoundly different for any two simulation runs in that events arising from the stochastic noise in the pseudorandom number sequence are amplified. As the population size is increased or, equivalently, the mutation rate is increased, these epochs become smaller but do not entirely disappear.

  4. Statistical Dynamics of Regional Populations and Economies

    CERN Document Server

    Huo, Jie; Hao, Rui; Wang, Peng

    2016-01-01

    A practical statistical analysis on the regional populations and GDPs of China is conducted. The result shows that the distribution of the populations and that of the GDPs obeys the shifted power law, respectively. To understand these characteristics, a generalized Langevin equation describing variation of population is proposed based on the correlation between population and GDP as well as the random fluctuations of the related factors. The equation is transformed into the Fokker-Plank equation, and the solution demonstrates a transform of population distribution from the normal Gaussian distribution to a shifted power law. It also suggests a critical point of time at which the transform occurs. The shifted power law distribution in the supercritical situation is qualitatively in accordance with the practical result. The distribution of the GDPs is derived based on the Cobb-Douglas production function, and presents a change from a shifted power law to the Gaussian distribution. This result indicates that the...

  5. POPULATION DYNAMICS OF PSEUDO-NITZSCHIA SPECIES ...

    African Journals Online (AJOL)

    nb

    be ASP free. However, further studies are required to ascertain DA production in coastal waters of Tanzania. ... in the region poses a threat to human health and to the developing ..... relationship with the population density of. Pseudo-nitzschia.

  6. Infections of Wolbachia may destabilize mosquito population dynamics.

    Science.gov (United States)

    Telschow, Arndt; Grziwotz, Florian; Crain, Philip; Miki, Takeshi; Mains, James W; Sugihara, George; Dobson, Stephen L; Hsieh, Chih-Hao

    2017-09-07

    Recent efforts in controlling mosquito-borne diseases focus on biocontrol strategies that incapacitate pathogens inside mosquitoes by altering the mosquito's microbiome. A case in point is the introduction of Wolbachia into natural mosquito populations in order to eliminate Dengue virus. However, whether this strategy can successfully control vector-borne diseases is debated; particularly, how artificial infection affects population dynamics of hosts remains unclear. Here, we show that natural Wolbachia infections are associated with unstable mosquito population dynamics by contrasting Wolbachia-infected versus uninfected cage populations of the Asian tiger mosquito (Aedes albopictus). By analyzing weekly data of adult mosquito abundances, we found that the variability of the infected populations is significantly higher than that of the uninfected. The elevated population variability is explained by increased instability in dynamics, as quantified by system nonlinearity (i.e., state-dependence). In addition, predictability of infected populations is substantially lower. A mathematical model analysis suggests that Wolbachia may alter mosquito population dynamics by modifying larval competition of hosts. These results encourage examination for effects of artificial Wolbachia establishment on mosquito populations, because an enhancement of population variability with reduced predictability could pose challenges in management. Our findings have implications for application of microbiome alterations in biocontrol programs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Epidemiology of childhood Guillain-Barré syndrome as a cause of acute flaccid paralysis in Honduras: 1989-1999.

    Science.gov (United States)

    Molinero, Marco R; Varon, Daniel; Holden, Kenton R; Sladky, John T; Molina, Ida B; Cleaves, Francisco

    2003-11-01

    The objective of this study was to investigate the incidence of acute flaccid paralysis in the pediatric population of Honduras over an 11-year period, determine what percentage of acute flaccid paralysis was Guillain-Barré syndrome, and identify the epidemiologic features of Guillain-Barré syndrome. There were 546 childhood cases of acute flaccid paralysis seen between January 1989 and December 1999 at the Hospital Escuela Materno-Infantil in Tegucigalpa, Honduras. Of these cases with acute flaccid paralysis, 394 (72.2%) were diagnosed with Guillain-Barré syndrome. Our incidence of Guillain-Barré syndrome in the Honduran pediatric population (1.37/100,000 per year) is higher than that shown in other studies. There was a significantly higher incidence of Guillain-Barré syndrome in younger children (ages 1-4 years), a significant preponderance of cases from rural areas, and a mild predominance in boys but a typical clinical presentation. The Honduran pediatric Guillain-Barré syndrome population had an increased mortality rate. Guillain-Barré syndrome has become the leading cause of childhood paralysis in Honduras. A better understanding of the population at highest risk and opportunities for earlier intervention with more effective therapeutic modalities may permit reducing the mortality among Honduran children who develop Guillain-Barré syndrome.

  8. Phase-space approach to multi-population dynamics

    CERN Document Server

    Budko, Neil V

    2015-01-01

    Simultaneous deterministic dynamics of multiple populations described by a large set of ODE's is considered in the phase space of population sizes and ODE's parameters. The problem is formulated as a multidimensional phase-space conservation law and is solved explicitly for non-interacting multi-population models. Solutions for populations competing for a limited resource and populations with migration are obtained by simple iterative methods. The proposed approach also allows considering phase-space interaction between populations, which is intractable by other methods.

  9. Impact of climate change on fish population dynamics in the baltic sea: a dynamical downscaling investigation

    DEFF Research Database (Denmark)

    Mackenzie, Brian R; Meier, H E Markus; Lindegren, Martin

    2012-01-01

    Understanding how climate change, exploitation and eutrophication will affect populations and ecosystems of the Baltic Sea can be facilitated with models which realistically combine these forcings into common frameworks. Here, we evaluate sensitivity of fish recruitment and population dynamics...

  10. Short-term service trips and the interprofessional team: a perspective from Honduras.

    Science.gov (United States)

    VanderWielen, Lynn M; Halder, Gabriela E; Enurah, Alexander S; Pearson, Catherine; Stevens, Michael P; Crossman, Steven H

    2015-03-01

    Short-term service trips from the USA annually spend over $250 million dollars to provide healthcare to individuals in developing nations. These trips often uniquely define goals as related to changes in the host population and overlook the valuable benefits potentially incurred by the trip volunteers. The Honduras Outreach Medical Brigada Relief Effort utilizes an interprofessional team approach to develop the dual goals of improving health and quality of life in host communities and improving interprofessional teamwork values and skills among participants. This article outlines details of this program, describes on-going evaluation work and discusses the interprofessional implications from this project.

  11. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras

    Directory of Open Access Journals (Sweden)

    Gustavo A Fontecha

    2014-07-01

    Full Text Available Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt “CVMNK” genotype in codons 72-76.

  12. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras.

    Science.gov (United States)

    Fontecha, Gustavo A; Sanchez, Ana L; Mendoza, Meisy; Banegas, Engels; Mejía-Torres, Rosa E

    2014-07-01

    Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt "CVMNK" genotype in codons 72-76.

  13. Population dynamics of Anopheles nuneztovari in Colombia.

    Science.gov (United States)

    Naranjo-Díaz, Nelson; Sallum, Maria Anice M; Correa, Margarita M

    2016-11-01

    Anopheles nuneztovari is an important Colombian malaria vector widespread on both sides of the Andean Mountains, presenting morphological, behavioral and genetic heterogeneity throughout the country. The aim of this study was to evaluate whether the population structure and distribution of An. nuneztovari in Colombia are associated with ecological and physical barriers present in a heterogeneous landscape. Further, differences in behavior were addressed. A total of 5392 specimens of An. nuneztovari were collected. Mitochondrial and nuclear marker analyses detected subdivision among the northwest-west, northeast and east populations. For both markers, isolation by distance (~53%) and isolation by resistance (>30%) were determinants of population genetic differentiation. This suggests that physical barriers, geographical distance and ecological differences on both sides of the Andean Mountains promoted the genetic differentiation and population subdivision of An. nuneztovari in Colombia. This species showed the highest biting activity after 20:00h; indoor and outdoor preferences were found in all localities. These results indicated that the most effective interventions for controlling vector populations on both sides of the Andes need to be region-specific. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Population dynamics of estuarine amphipods in Cochin backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, K.K.C.; Gopalakrishnan, T.C.; Venugopal, P.; Peter, G.; Jayalakshmy, K.V.; Rao, T.S.S.

    Population dynamics of 11 gammarid amphipod species (belonging to 9 genera), collected from Cochin backwaters, have been studied for the first time, based on an year round collection. The species are : Corophium triaenonyx Stebbing, Photis digitata...

  15. Population dynamics of the king rails, Rallus elegans

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report describes the findings of research conducted by a team of biologists from East Carolina University. The project ‘Population Dynamics of the King Rail,...

  16. Effects of culling on mesopredator population dynamics.

    Directory of Open Access Journals (Sweden)

    James C Beasley

    Full Text Available Anthropogenic changes in land use and the extirpation of apex predators have facilitated explosive growth of mesopredator populations. Consequently, many species have been subjected to extensive control throughout portions of their range due to their integral role as generalist predators and reservoirs of zoonotic disease. Yet, few studies have monitored the effects of landscape composition or configuration on the demographic or behavioral response of mesopredators to population manipulation. During 2007 we removed 382 raccoons (Procyon lotor from 30 forest patches throughout a fragmented agricultural ecosystem to test hypotheses regarding the effects of habitat isolation on population recovery and role of range expansion and dispersal in patch colonization of mesopredators in heterogeneous landscapes. Patches were allowed to recolonize naturally and demographic restructuring of patches was monitored from 2008-2010 using mark-recapture. An additional 25 control patches were monitored as a baseline measure of demography. After 3 years only 40% of experimental patches had returned to pre-removal densities. This stagnant recovery was driven by low colonization rates of females, resulting in little to no within-patch recruitment. Colonizing raccoons were predominantly young males, suggesting that dispersal, rather than range expansion, was the primary mechanism driving population recovery. Contrary to our prediction, neither landscape connectivity nor measured local habitat attributes influenced colonization rates, likely due to the high dispersal capability of raccoons and limited role of range expansion in patch colonization. Although culling is commonly used to control local populations of many mesopredators, we demonstrate that such practices create severe disruptions in population demography that may be counterproductive to disease management in fragmented landscapes due to an influx of dispersing males into depopulated areas. However, given

  17. A linear model of population dynamics

    Science.gov (United States)

    Lushnikov, A. A.; Kagan, A. I.

    2016-08-01

    The Malthus process of population growth is reformulated in terms of the probability w(n,t) to find exactly n individuals at time t assuming that both the birth and the death rates are linear functions of the population size. The master equation for w(n,t) is solved exactly. It is shown that w(n,t) strongly deviates from the Poisson distribution and is expressed in terms either of Laguerre’s polynomials or a modified Bessel function. The latter expression allows for considerable simplifications of the asymptotic analysis of w(n,t).

  18. Real-Time Bioluminescent Tracking of Cellular Population Dynamics

    OpenAIRE

    Close, Dan; Xu, Tingling; Ripp, Steven; Sayler, Gary

    2014-01-01

    Cellular population dynamics are routinely monitored across many diverse fields for a variety of purposes. In general, these dynamics are assayed either through the direct counting of cellular aliquots followed by extrapolation to the total population size, or through the monitoring of signal intensity from any number of externally stimulated reporter proteins. While both viable methods, here we describe a novel technique that allows for the automated, non-destructive tracking of cellular pop...

  19. Real-Time Bioluminescent Tracking of Cellular Population Dynamics

    OpenAIRE

    Close, Dan; Xu, Tingling; Ripp, Steven; Sayler, Gary

    2014-01-01

    Cellular population dynamics are routinely monitored across many diverse fields for a variety of purposes. In general, these dynamics are assayed either through the direct counting of cellular aliquots followed by extrapolation to the total population size, or through the monitoring of signal intensity from any number of externally stimulated reporter proteins. While both viable methods, here we describe a novel technique that allows for the automated, non-destructive tracking of cellular pop...

  20. Passivity analysis of higher order evolutionary dynamics and population games

    KAUST Repository

    Mabrok, Mohamed

    2017-01-05

    Evolutionary dynamics describe how the population composition changes in response to the fitness levels, resulting in a closed-loop feedback system. Recent work established a connection between passivity theory and certain classes of population games, namely so-called “stable games”. In particular, it was shown that a combination of stable games and (an analogue of) passive evolutionary dynamics results in stable convergence to Nash equilibrium. This paper considers the converse question of necessary conditions for evolutionary dynamics to exhibit stable behaviors for all generalized stable games. Using methods from robust control analysis, we show that if an evolutionary dynamic does not satisfy a passivity property, then it is possible to construct a generalized stable game that results in instability. The results are illustrated on selected evolutionary dynamics with particular attention to replicator dynamics, which are also shown to be lossless, a special class of passive systems.

  1. The frankincense tree of Ethiopia : ecology, productivity and population dynamics

    NARCIS (Netherlands)

    Eshete Wassie, A.

    2011-01-01

    Keywords: Boswellian papyrifera, Frankincense tree, matrix model, population dynamics,
    population bottleneck, tapping. Combretum – Terminalia woodlands and Acacia – Commiphora woodlands are the two
    dominant vegetation types that cover large parts of the dry land areas in Eth

  2. Ruffed grouse population dynamics in the central and southern Appalachians

    Science.gov (United States)

    John M. Giuliano Tirpak; C. Allan Miller; Thomas J. Allen; Steve Bittner; David A. Buehler; John W. Edwards; Craig A. Harper; William K. Igo; Gary W. Norman; M. Seamster; Dean F. Stauffer

    2006-01-01

    Ruffed grouse (Bonasa urnbellus; hereafter grouse) populations in the central and southern Appalachians are in decline. However, limited information on the dynamics of these populations prevents the development of effective management strategies to reverse these trends. We used radiotelemetry data collected on grouse to parameterize 6 models of...

  3. Contributions of Alan C. Lazer to mathematical population dynamics

    Directory of Open Access Journals (Sweden)

    Chris Cosner

    2000-10-01

    Full Text Available This paper is a survey of the contributions that Professor Alan C. Lazer has made to the mathematical theory of population dynamics. Specific areas where Professor Lazer has made important contributions include time periodic population models with diffusion and nonautonomous models for many competing species.

  4. Stage-Structured Population Dynamics of AEDES AEGYPTI

    Science.gov (United States)

    Yusoff, Nuraini; Budin, Harun; Ismail, Salemah

    Aedes aegypti is the main vector in the transmission of dengue fever, a vector-borne disease affecting world population living in tropical and sub-tropical countries. Better understanding of the dynamics of its population growth will help in the efforts of controlling the spread of this disease. In looking at the population dynamics of Aedes aegypti, this paper explored the stage-structured modeling of the population growth of the mosquito using the matrix population model. The life cycle of the mosquito was divided into five stages: eggs, larvae, pupae, adult1 and adult2. Developmental rates were obtained for the average Malaysian temperature and these were used in constructing the transition matrix for the matrix model. The model, which was based only on temperature, projected that the population of Aedes aegypti will blow up with time, which is not realistic. For further work, other factors need to be taken into account to obtain a more realistic result.

  5. Explaining "Noise" as Environmental Variations in Population Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ginn, Timothy R.; Loge, Frank J.; Scheibe, Timothy D.

    2007-03-01

    The impacts of human activities on our own and other populations on the plant are making news at an alarming pace. Global warming, ocean and freshwater contamination and acidification, deforestation, habitat destruction and incursion, and in general a burgeoning human population are associated with a complete spectrum of changes to the dynamics of populations. Effects on songbirds, insects, coral reefs, ocean mammals, anadromous fishes, just to name a few, and humans, have been linked to human industry and population growth. The linkage, however, remains often ghostly and often tenuous at best, because of the difficulty in quantitatively combining ecological processes with environmental fate and transport processes. Establishing quantitative tools, that is, models, for the combined dynamics of populations and environmental chemical/thermal things is needed. This truly interdisciplinary challenge is briefly reviewed, and two approaches to integrating chemical and biological intermingling are addressed in the context of salmon populations in the Pacific Northwest.

  6. AN INVARIANCE PRINCIPLE IN LARGE POPULATION STOCHASTIC DYNAMIC GAMES

    Institute of Scientific and Technical Information of China (English)

    Minyi HUANG; Peter E. CAINES; Roland P. MALHAM(E)

    2007-01-01

    We study large population stochastic dynamic games where the so-called Nash certainty equivalence based control laws are implemented by the individual players. We first show a martingale property for the limiting control problem of a single agent and then perform averaging across the population; this procedure leads to a constant value for the martingale which shows an invariance property of the population behavior induced by the Nash strategies.

  7. Lessons from silage adoption studies in Honduras

    Directory of Open Access Journals (Sweden)

    Christoph Reiber

    2013-12-01

    Full Text Available To date, silage adoption has been low in the tropics, particularly under smallholder conditions. Innovation and adoption processes of silage technologies were promoted in drought-constrained areas of Honduras using a flexible, site-specific and participatory research and extension approach. A total of about 250 farmers participated in training workshops and field days conducted in 13 locations. Smallholders successfully ensiled maize, sorghum and/or Pennisetum spp., mainly in heap and earth silos, while adoption of little bag silage (LBS was low. LBS proved useful as a demonstration, experimentation and learning tool. A ‘silage boom’ occurred in 5 locations, where favorable adoption conditions included the presence of demonstration farms and involvement of key innovators, lack of alternative dry season feeds, perceived benefits of silage feeding, a favorable milk market and both extension continuity and intensity. The lack of chopping equipment was the main reason for non-adoption by poor smallholders. The study showed that, when targeting production system needs and farmer demands, silage promotion can lead to significant adoption, including at smallholder level, in the tropics. This experience could contribute to an increase in effectiveness and sustainability of silage extension in similar situations elsewhere.

  8. Modelling the Dynamics of an Aedes albopictus Population

    CERN Document Server

    Basuki, Thomas Anung; Barbuti, Roberto; Maggiolo-Schettini, Andrea; Milazzo, Paolo; Rossi, Elisabetta; 10.4204/EPTCS.33.2

    2010-01-01

    We present a methodology for modelling population dynamics with formal means of computer science. This allows unambiguous description of systems and application of analysis tools such as simulators and model checkers. In particular, the dynamics of a population of Aedes albopictus (a species of mosquito) and its modelling with the Stochastic Calculus of Looping Sequences (Stochastic CLS) are considered. The use of Stochastic CLS to model population dynamics requires an extension which allows environmental events (such as changes in the temperature and rainfalls) to be taken into account. A simulator for the constructed model is developed via translation into the specification language Maude, and used to compare the dynamics obtained from the model with real data.

  9. Modelling the Dynamics of an Aedes albopictus Population

    Directory of Open Access Journals (Sweden)

    Thomas Anung Basuki

    2010-08-01

    Full Text Available We present a methodology for modelling population dynamics with formal means of computer science. This allows unambiguous description of systems and application of analysis tools such as simulators and model checkers. In particular, the dynamics of a population of Aedes albopictus (a species of mosquito and its modelling with the Stochastic Calculus of Looping Sequences (Stochastic CLS are considered. The use of Stochastic CLS to model population dynamics requires an extension which allows environmental events (such as changes in the temperature and rainfalls to be taken into account. A simulator for the constructed model is developed via translation into the specification language Maude, and used to compare the dynamics obtained from the model with real data.

  10. Co-infection alters population dynamics of infectious disease.

    Science.gov (United States)

    Susi, Hanna; Barrès, Benoit; Vale, Pedro F; Laine, Anna-Liisa

    2015-01-08

    Co-infections by multiple pathogen strains are common in the wild. Theory predicts co-infections to have major consequences for both within- and between-host disease dynamics, but data are currently scarce. Here, using common garden populations of Plantago lanceolata infected by two strains of the pathogen Podosphaera plantaginis, either singly or under co-infection, we find the highest disease prevalence in co-infected treatments both at the host genotype and population levels. A spore-trapping experiment demonstrates that co-infected hosts shed more transmission propagules than singly infected hosts, thereby explaining the observed change in epidemiological dynamics. Our experimental findings are confirmed in natural pathogen populations-more devastating epidemics were measured in populations with higher levels of co-infection. Jointly, our results confirm the predictions made by theoretical and experimental studies for the potential of co-infection to alter disease dynamics across a large host-pathogen metapopulation.

  11. Landslides triggered by Hurricane Mitch in Tegucigalpa, Honduras

    Science.gov (United States)

    Harp, Edwin L.; Castaneda, Mario; Held, Matthew D.

    2002-01-01

    The arrival of Hurricane Mitch in Honduras in the latter part of the 1998 hurricane season produced effects that were unprecedented in their widespread nature throughout Central America. After winds from the storm had blown down more than 70 percent of the conifer forest on the Bay Island of Guanaja, the hurricane turned inland and stalled over the mainland of Honduras for 3 days. The resulting deluge of rainfall produced devastating flooding and landslides that resulted in more than 9,000 fatalities and 3 million people displaced. Although the eye of Hurricane Mitch passed through the northern part of Honduras, the greatest rainfall totals and intensities occurred in the southern part of the country near Choluteca. For the three days October 29-31, 1998, total rainfall at Choluteca exceeded 900 mm. Not surprisingly, it was in this area that the highest landslide concentrations occurred.

  12. Assessing Knowledge and Perceptions Related to Preventive Methods and Treatment of Malaria in the Local Endemic Area of Trujillo, Honduras.

    Science.gov (United States)

    Campodonico, Joanna; Sevilla-Martir, Javier; Arrizabalaga, Gustavo; Kochhar, Komal

    2015-01-01

    Malaria in Honduras is endemic and accounts for 40% of the total cases in Central America. Our goal was to assess knowledge of preventive methods and current treatment of malaria among the affected community of Trujillo, Honduras. A cross-sectional survey was administered to 71 individuals. Most respondents had a good understanding about common malaria symptoms but not about the complications associated with severe cases. More important, we found that less than 20% of the respondents recognized indoor residual sprays and insecticide-treated nets as effective preventive measures, which are the most efficient preventive methods. Our study highlights the perceptions the people of Trujillo have about malaria. From our observations, we put forward recommendations to implement a comprehensive campaign to educate the Trujillo population about malaria preventive methods and to recruit local and international efforts to distribute insecticide-treated nets.

  13. Molecular diversity of Mycobacterium tuberculosis isolates from patients with tuberculosis in Honduras

    Directory of Open Access Journals (Sweden)

    Ghebremichael Solomon

    2010-08-01

    Full Text Available Abstract Background Tuberculosis persists as a public health problem in Honduras. A better knowledge of the molecular characteristics of Mycobacterium tuberculosis strains will contribute to understand the transmission dynamics of the disease within the country. The aim of this study was to provide an insight of the genetic biodiversity of M. tuberculosis clinical isolates collected in Honduras between 1994 and 2002. Genotyping was performed using spoligotyping and RFLP. The spoligotypes obtained were compared with the SITVIT2 proprietary database of the Pasteur Institute of Guadeloupe. Results Spoligotyping grouped 84% of the isolates into 27 clusters (2 to 43 strains per cluster. Of the 44 shared international types (SITs identified among the Honduran stains, 8 SITs were newly identified either within the present study or after match with an orphan type previously identified in the SITVIT2 database. In addition, 16 patterns corresponded to orphan, previously unreported isolates. The Latin American Mediterranean (LAM lineage was the most common in this study; 55% of the strains belonged to this family. Other genotypes found were Haarlem (16%, T (16%, X-clade (6%, Unknown signature (5% and S (1%. Only one Beijing strain was identified (0.5%. We observed a high degree of diversity after characterizing the 43 isolates belonging to the main spoligotyping cluster (SIT 33, LAM3 with IS6110-RFLP. A total of 35 different RFLP-fingerprints were detected, of which 6 patterns corresponded to the same number of clusters comprising 14 strains. Conclusions The findings obtained in this study show that tuberculosis transmission in Honduras is due to modern M. tuberculosis lineages with high level of biodiversity.

  14. feedback between population and evolutionary dynamics determines the fate of social microbial populations.

    Science.gov (United States)

    Sanchez, Alvaro; Gore, Jeff

    2013-01-01

    The evolutionary spread of cheater strategies can destabilize populations engaging in social cooperative behaviors, thus demonstrating that evolutionary changes can have profound implications for population dynamics. At the same time, the relative fitness of cooperative traits often depends upon population density, thus leading to the potential for bi-directional coupling between population density and the evolution of a cooperative trait. Despite the potential importance of these eco-evolutionary feedback loops in social species, they have not yet been demonstrated experimentally and their ecological implications are poorly understood. Here, we demonstrate the presence of a strong feedback loop between population dynamics and the evolutionary dynamics of a social microbial gene, SUC2, in laboratory yeast populations whose cooperative growth is mediated by the SUC2 gene. We directly visualize eco-evolutionary trajectories of hundreds of populations over 50-100 generations, allowing us to characterize the phase space describing the interplay of evolution and ecology in this system. Small populations collapse despite continual evolution towards increased cooperative allele frequencies; large populations with a sufficient number of cooperators "spiral" to a stable state of coexistence between cooperator and cheater strategies. The presence of cheaters does not significantly affect the equilibrium population density, but it does reduce the resilience of the population as well as its ability to adapt to a rapidly deteriorating environment. Our results demonstrate the potential ecological importance of coupling between evolutionary dynamics and the population dynamics of cooperatively growing organisms, particularly in microbes. Our study suggests that this interaction may need to be considered in order to explain intraspecific variability in cooperative behaviors, and also that this feedback between evolution and ecology can critically affect the demographic fate of

  15. feedback between population and evolutionary dynamics determines the fate of social microbial populations.

    Directory of Open Access Journals (Sweden)

    Alvaro Sanchez

    Full Text Available The evolutionary spread of cheater strategies can destabilize populations engaging in social cooperative behaviors, thus demonstrating that evolutionary changes can have profound implications for population dynamics. At the same time, the relative fitness of cooperative traits often depends upon population density, thus leading to the potential for bi-directional coupling between population density and the evolution of a cooperative trait. Despite the potential importance of these eco-evolutionary feedback loops in social species, they have not yet been demonstrated experimentally and their ecological implications are poorly understood. Here, we demonstrate the presence of a strong feedback loop between population dynamics and the evolutionary dynamics of a social microbial gene, SUC2, in laboratory yeast populations whose cooperative growth is mediated by the SUC2 gene. We directly visualize eco-evolutionary trajectories of hundreds of populations over 50-100 generations, allowing us to characterize the phase space describing the interplay of evolution and ecology in this system. Small populations collapse despite continual evolution towards increased cooperative allele frequencies; large populations with a sufficient number of cooperators "spiral" to a stable state of coexistence between cooperator and cheater strategies. The presence of cheaters does not significantly affect the equilibrium population density, but it does reduce the resilience of the population as well as its ability to adapt to a rapidly deteriorating environment. Our results demonstrate the potential ecological importance of coupling between evolutionary dynamics and the population dynamics of cooperatively growing organisms, particularly in microbes. Our study suggests that this interaction may need to be considered in order to explain intraspecific variability in cooperative behaviors, and also that this feedback between evolution and ecology can critically affect the

  16. Population dynamics: Social security, markets, and families.

    Science.gov (United States)

    Mason, Andrew W; Lee, Ronald D; Lee, Sang-Hyop

    2010-07-01

    Upward intergenerational flows - from the working ages to old age - are increasing substantially in the advanced industrialized countries and are much larger than in developing countries. Population aging is the most important factor leading to this change. Thus, in the absence of a major demographic shift, e.g., a return to high fertility, an increase in upward flows is inevitable. Even so, three other important factors will influence the magnitudes of upward flows. First, labor income varies at older ages due to differences in average age at retirement, productivity, unemployment, and hours worked. Second, the age patterns of consumption at older ages vary primarily due to differences in spending on health. Third, spending on human capital, i.e., spending child health and education, varies. Human capital spending competes with spending on the elderly, but it also increases the productivity of subsequent generations of workers and the resources available to support consumption in old age. All contemporary societies rely on a variety of institutions and economic mechanisms to shift economic resources from the working ages to the dependent ages - the young and the old. Three institutions dominate intergenerational flows: governments which implement social security, education, and other public transfer programs; markets which are key to the accumulation of assets, e.g., funded pensions and housing; and families which provide economic support to children in all societies and to the elderly in many. The objectives of this paper are, first, to describe how population aging and other changes influence the direction and magnitude of intergenerational flows; and, second, to contrast the institutional approaches to intergenerational flows as they are practiced around the world. The paper relies extensively on National Transfer Accounts, a system for measuring economic flows across age in a manner consistent with the UN System of National Accounts. These accounts are

  17. Population dynamics and the ecological stability of obligate pollination mutualisms

    Science.gov (United States)

    Holland, J. Nathaniel; DeAngelis, Donald L.

    2001-01-01

    Mutualistic interactions almost always produce both costs and benefits for each of the interacting species. It is the difference between gross benefits and costs that determines the net benefit and the per-capita effect on each of the interacting populations. For example, the net benefit of obligate pollinators, such as yucca and senita moths, to plants is determined by the difference between the number of ovules fertilized from moth pollination and the number of ovules eaten by the pollinator's larvae. It is clear that if pollinator populations are large, then, because many eggs are laid, costs to plants are large, whereas, if pollinator populations are small, gross benefits are low due to lack of pollination. Even though the size and dynamics of the pollinator population are likely to be crucial, their importance has been neglected in the investigation of mechanisms, such as selective fruit abortion, that can limit costs and increase net benefits. Here, we suggest that both the population size and dynamics of pollinators are important in determining the net benefits to plants, and that fruit abortion can significantly affect these. We develop a model of mutualism between populations of plants and their pollinating seed-predators to explore the ecological consequences of fruit abortion on pollinator population dynamics and the net effect on plants. We demonstrate that the benefit to a plant population is unimodal as a function of pollinator abundance, relative to the abundance of flowers. Both selective abortion of fruit with eggs and random abortion of fruit, without reference to whether they have eggs or not, can limit pollinator population size. This can increase the net benefits to the plant population by limiting the number of eggs laid, if the pollination rate remains high. However, fruit abortion can possibly destabilize the pollinator population, with negative consequences for the plant population.

  18. Strongly Deterministic Population Dynamics in Closed Microbial Communities

    Directory of Open Access Journals (Sweden)

    Zak Frentz

    2015-10-01

    Full Text Available Biological systems are influenced by random processes at all scales, including molecular, demographic, and behavioral fluctuations, as well as by their interactions with a fluctuating environment. We previously established microbial closed ecosystems (CES as model systems for studying the role of random events and the emergent statistical laws governing population dynamics. Here, we present long-term measurements of population dynamics using replicate digital holographic microscopes that maintain CES under precisely controlled external conditions while automatically measuring abundances of three microbial species via single-cell imaging. With this system, we measure spatiotemporal population dynamics in more than 60 replicate CES over periods of months. In contrast to previous studies, we observe strongly deterministic population dynamics in replicate systems. Furthermore, we show that previously discovered statistical structure in abundance fluctuations across replicate CES is driven by variation in external conditions, such as illumination. In particular, we confirm the existence of stable ecomodes governing the correlations in population abundances of three species. The observation of strongly deterministic dynamics, together with stable structure of correlations in response to external perturbations, points towards a possibility of simple macroscopic laws governing microbial systems despite numerous stochastic events present on microscopic levels.

  19. Population dynamics: Social security, markets, and families

    Science.gov (United States)

    Lee, Ronald D.; Lee, Sang-Hyop

    2015-01-01

    Upward intergenerational flows – from the working ages to old age – are increasing substantially in the advanced industrialized countries and are much larger than in developing countries. Population aging is the most important factor leading to this change. Thus, in the absence of a major demographic shift, e.g., a return to high fertility, an increase in upward flows is inevitable. Even so, three other important factors will influence the magnitudes of upward flows. First, labor income varies at older ages due to differences in average age at retirement, productivity, unemployment, and hours worked. Second, the age patterns of consumption at older ages vary primarily due to differences in spending on health. Third, spending on human capital, i.e., spending child health and education, varies. Human capital spending competes with spending on the elderly, but it also increases the productivity of subsequent generations of workers and the resources available to support consumption in old age. All contemporary societies rely on a variety of institutions and economic mechanisms to shift economic resources from the working ages to the dependent ages – the young and the old. Three institutions dominate intergenerational flows: governments which implement social security, education, and other public transfer programs; markets which are key to the accumulation of assets, e.g., funded pensions and housing; and families which provide economic support to children in all societies and to the elderly in many. The objectives of this paper are, first, to describe how population aging and other changes influence the direction and magnitude of intergenerational flows; and, second, to contrast the institutional approaches to intergenerational flows as they are practiced around the world. The paper relies extensively on National Transfer Accounts, a system for measuring economic flows across age in a manner consistent with the UN System of National Accounts. These accounts are

  20. Locally dispersing populations in heterogeneous dynamic landscapes with spatiotemporal correlations. II. Habitat driven by voter dynamics.

    Science.gov (United States)

    Hiebeler, David E; Hill, Jack L

    2016-10-21

    We examine a spatially explicit population model on a dynamic landscape with suitable and unsuitable habitat driven by voter or contagion dynamics. We consider four cases, consisting of all combinations of local and global interactions for both population dispersal and habitat dynamics. For both local and global population dispersal, using local habitat dynamics always increases population density relative to the case with global habitat dynamics, due to the resulting segregation of habitat turnover, decrease in effective habitat turnover rate, and presence of stable habitat corridors. With global habitat dynamics, a population using local dispersal exhibits lower density than one with global dispersal due to local crowding as well as frequent disturbance due to habitat transitions. On the other hand, with local habitat dynamics, a population using local dispersal can exploit suitable habitat patches and use dynamic corridors to colonize new regions. The latter effect is not seen with static landscapes, where clustered habitat can lead to the isolation of suitable patches due to surrounding unsuitable habitat.

  1. An individual-based model of zebrafish population dynamics accounting for energy dynamics.

    Directory of Open Access Journals (Sweden)

    Rémy Beaudouin

    Full Text Available Developing population dynamics models for zebrafish is crucial in order to extrapolate from toxicity data measured at the organism level to biological levels relevant to support and enhance ecological risk assessment. To achieve this, a dynamic energy budget for individual zebrafish (DEB model was coupled to an individual based model of zebrafish population dynamics (IBM model. Next, we fitted the DEB model to new experimental data on zebrafish growth and reproduction thus improving existing models. We further analysed the DEB-model and DEB-IBM using a sensitivity analysis. Finally, the predictions of the DEB-IBM were compared to existing observations on natural zebrafish populations and the predicted population dynamics are realistic. While our zebrafish DEB-IBM model can still be improved by acquiring new experimental data on the most uncertain processes (e.g. survival or feeding, it can already serve to predict the impact of compounds at the population level.

  2. Interacting trophic forcing and the population dynamics of herring

    DEFF Research Database (Denmark)

    Lindegren, Martin; Ostman, Orjan; Gardmark, Anna

    2011-01-01

    Small pelagic fish occupy a central position in marine ecosystems worldwide, largely by determining the energy transfer from lower trophic levels to predators at the top of the food web, including humans. Population dynamics of small pelagic fish may therefore be regulated neither strictly bottom......-up nor top-down, but rather through multiple external and internal drivers. While in many studies single drivers have been identified, potential synergies of multiple factors, as well as their relative importance in regulating population dynamics of small pelagic fish, is a largely unresolved issue....... Using a statistical, age-structured modeling approach, we demonstrate the relative importance and influence of bottom-up (e.g., climate, zooplankton availability) and top-down (i.e., fishing and predation) factors on the population dynamics of Bothnian Sea herring (Clupea harengus) throughout its life...

  3. Real-Time Bioluminescent Tracking of Cellular Population Dynamics

    Science.gov (United States)

    Close, Dan; Xu, Tingling; Ripp, Steven; Sayler, Gary

    2015-01-01

    Cellular population dynamics are routinely monitored across many diverse fields for a variety of purposes. In general, these dynamics are assayed either through the direct counting of cellular aliquots followed by extrapolation to the total population size, or through the monitoring of signal intensity from any number of externally stimulated reporter proteins. While both viable methods, here we describe a novel technique that allows for the automated, non-destructive tracking of cellular population dynamics in real-time. This method, which relies on the detection of a continuous bioluminescent signal produced through expression of the bacterial luciferase gene cassette, provides a low cost, low time-intensive means for generating additional data compared to alternative methods. PMID:24166372

  4. Real-Time Bioluminescent Tracking of Cellular Population Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Close, Dan [University of Tennessee, Knoxville (UTK); Sayler, Gary Steven [ORNL; Xu, Tingting [ORNL; Ripp, Steven Anthony [ORNL

    2014-01-01

    Cellular population dynamics are routinely monitored across many diverse fields for a variety of purposes. In general, these dynamics are assayed either through the direct counting of cellular aliquots followed by extrapolation to the total population size, or through the monitoring of signal intensity from any number of externally stimulated reporter proteins. While both viable methods, here we describe a novel technique that allows for the automated, non-destructive tracking of cellular population dynamics in real-time. This method, which relies on the detection of a continuous bioluminescent signal produced through expression of the bacterial luciferase gene cassette, provides a low cost, low time-intensive means for generating additional data compared to alternative methods.

  5. Dynamical quorum sensing and clustering dynamics in a population of spatially distributed active rotators

    Science.gov (United States)

    Sakaguchi, Hidetsugu; Maeyama, Satomi

    2013-02-01

    A model of clustering dynamics is proposed for a population of spatially distributed active rotators. A transition from excitable to oscillatory dynamics is induced by the increase of the local density of active rotators. It is interpreted as dynamical quorum sensing. In the oscillation regime, phase waves propagate without decay, which generates an effectively long-range interaction in the clustering dynamics. The clustering process becomes facilitated and only one dominant cluster appears rapidly as a result of the dynamical quorum sensing. An exact localized solution is found to a simplified model equation, and the competitive dynamics between two localized states is studied numerically.

  6. Cumulant dynamics in a finite population linkage equilibrium theory

    CERN Document Server

    Rattray, M; Rattray, Magnus; Shapiro, Jonathan L.

    1999-01-01

    The evolution of a finite population at linkage equilibrium is described in terms of the dynamics of phenotype distribution cumulants. This provides a powerful method for describing evolutionary transients and we elucidate the relationship between the cumulant dynamics and the diffusion approximation. A separation of time-scales between the first and higher cumulants for low mutation rates is demonstrated in the diffusion limit and provides a significant simplification of the dynamical system. However, the diffusion limit may not be appropriate for strong selection as the standard Fisher-Wright model of genetic drift can break down in this case. Two novel examples of this effect are considered: we shown that the dynamics may depend on the number of loci under strong directional selection and that environmental variance results in a reduced effective population size. We also consider a simple model of a changing environment which cannot be described by a diffusion equation and we derive the optimal mutation ra...

  7. Estimating Traveler Populations at Airport and Cruise Terminals for Population Distribution and Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jochem, Warren C [ORNL; Sims, Kelly M [ORNL; Bright, Eddie A [ORNL; Urban, Marie L [ORNL; Rose, Amy N [ORNL; Coleman, Phil R [ORNL; Bhaduri, Budhendra L [ORNL

    2013-01-01

    In recent years, uses of high-resolution population distribution databases are increasing steadily for environmental, socioeconomic, public health, and disaster-related research and operations. With the development of daytime population distribution, temporal resolution of such databases has been improved. However, the lack of incorporation of transitional population, namely business and leisure travelers, leaves a significant population unaccounted for within the critical infrastructure networks, such as at transportation hubs. This paper presents two general methodologies for estimating passenger populations in airport and cruise port terminals at a high temporal resolution which can be incorporated into existing population distribution models. The methodologies are geographically scalable and are based on, and demonstrate how, two different transportation hubs with disparate temporal population dynamics can be modeled utilizing publicly available databases including novel data sources of flight activity from the Internet which are updated in near-real time. The airport population estimation model shows great potential for rapid implementation for a large collection of airports on a national scale, and the results suggest reasonable accuracy in the estimated passenger traffic. By incorporating population dynamics at high temporal resolutions into population distribution models, we hope to improve the estimates of populations exposed to or at risk to disasters, thereby improving emergency planning and response, and leading to more informed policy decisions.

  8. Dynamics of Sequence -Discrete Bacterial Populations Inferred Using Metagenomes

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Sarah; Bendall, Matthew; Kang, Dongwan; Froula, Jeff; Egan, Rob; Chan, Leong-Keat; Tringe, Susannah; McMahon, Katherine; Malmstrom, Rex

    2014-03-14

    From a multi-year metagenomic time series of two dissimilar Wisconsin lakes we have assembled dozens of genomes using a novel approach that bins contigs into distinct genome based on sequence composition, e.g. kmer frequencies, and contig coverage patterns at various times points. Next, we investigated how these genomes, which represent sequence-discrete bacterial populations, evolved over time and used the time series to discover the population dynamics. For example, we explored changes in single nucleotide polymorphism (SNP) frequencies as well as patterns of gene gain and loss in multiple populations. Interestingly, SNP diversity was purged at nearly every genome position in some populations during the course of this study, suggesting these populations may have experienced genome-wide selective sweeps. This represents the first direct, time-resolved observations of periodic selection in natural populations, a key process predicted by the ecotype model of bacterial diversification.

  9. An individual-based model of Zebrafish population dynamics accounting for energy dynamics

    DEFF Research Database (Denmark)

    Beaudouin, Remy; Goussen, Benoit; Piccini, Benjamin

    2015-01-01

    Developing population dynamics models for zebrafish is crucial in order to extrapolate from toxicity data measured at the organism level to biological levels relevant to support and enhance ecological risk assessment. To achieve this, a dynamic energy budget for individual zebrafish (DEB model......, the predictions of the DEB-IBM were compared to existing observations on natural zebrafish populations and the predicted population dynamics are realistic. While our zebrafish DEB-IBM model can still be improved by acquiring new experimental data on the most uncertain processes (e.g. survival or feeding), it can...

  10. An age-structured population balance model for microbial dynamics

    Directory of Open Access Journals (Sweden)

    Duarte M.V.E.

    2003-01-01

    Full Text Available This work presents an age-structured population balance model (ASPBM for a bioprocess in a continuous stirred-tank fermentor. It relates the macroscopic properties and dynamic behavior of biomass to the operational parameters and microscopic properties of cells. Population dynamics is governed by two time- and age-dependent density functions for living and dead cells, accounting for the influence of substrate and dissolved oxygen concentrations on cell division, aging and death processes. The ASPBM described biomass and substrate oscillations in aerobic continuous cultures as experimentally observed. It is noteworthy that a small data set consisting of nonsegregated measurements was sufficient to adjust a complex segregated mathematical model.

  11. Competitive Lotka-Volterra Population Dynamics with Jumps

    CERN Document Server

    Bao, Jianhai; Yin, Geroge; Yuan, Chenggui

    2011-01-01

    This paper considers competitive Lotka-Volterra population dynamics with jumps. The contributions of this paper are as follows. (a) We show stochastic differential equation (SDE) with jumps associated with the model has a unique global positive solution; (b) We discuss the uniform boundedness of $p$th moment with $p>0$ and reveal the sample Lyapunov exponents; (c) Using a variation-of-constants formula for a class of SDEs with jumps, we provide explicit solution for 1-dimensional competitive Lotka-Volterra population dynamics with jumps, and investigate the sample Lyapunov exponent for each component and the extinction of our $n$-dimensional model.

  12. La situación económica: social determinants of contraceptive use in rural Honduras.

    Science.gov (United States)

    Hall, Marissa G; Garrett, Jenna J; Barrington, Clare

    2014-01-01

    Contraceptive use is an important determinant of unintended pregnancy, but little is known about the social and structural factors that determine women's contraceptive use in rural Honduras. In this study, we aim to characterise the individual and social determinants of contraceptive use among women in rural Honduras. In 2011 and 2012, we conducted 14 interviews and 2 focus groups with women 18 years and older. In our analysis, we created a family-planning narrative for each participant and coded transcripts around key emergent themes related to these determinants. We found that social determinants--including poverty, gender dynamics and availability of family-planning methods--had a strong influence on contraceptive use among women in our sample. Study participants stated that they were faced with a difficult economic situation compounded by rising prices of basic goods and diminishing job opportunities. Paradoxically, at the same time that the economic situation led women to seek contraception, it also contributed to the structural barriers that limited their ability to obtain their method of choice and maintain continuous contraceptive use. Our findings suggest the need for multi-level efforts to create an enabling and sustainable environment for family planning among women in rural Honduras.

  13. Atlantic bluefin tuna: population dynamics, ecology, fisheries and management

    OpenAIRE

    Fromentin, Jean-Marc; Powers, Joseph

    2005-01-01

    Both old and new information on the biology and ecology of Atlantic bluefin tuna have confronted scientists with research challenges: research needs to be connected to current stock-assessment and management issues. We review recent studies on habitat, migrations and population structure, stressing the importance of electronic tagging results in the modification of our perception of bluefin tuna population dynamics and behaviour. Additionally, we question, from both scientific and management ...

  14. Workshop on Populations & Crowds: Dynamics, Disruptions and their Computational Models

    Science.gov (United States)

    2015-01-01

    behavior and, ultimately, what can be done to block contagion of hostile behavior in both population and crowd contexts. The workshop was organized at the...powerful in their ability to spread information and rapidly alter their collective behavior . Crowds can transition from loosely to tightly organized and...7 September, 2012 concentrating on organization , dynamics and disruption of populations and crowds. The purpose of this workshop was to bring

  15. The population dynamical consequences of density-dependent prophylaxis.

    Science.gov (United States)

    Reynolds, Jennifer J H; White, Andrew; Sherratt, Jonathan A; Boots, Mike

    2011-11-07

    When infectious disease transmission is density-dependent, the risk of infection will tend to increase with host population density. Since host defence mechanisms can be costly, individual hosts may benefit from increasing their investment in immunity in response to increasing population density. Such "density-dependent prophylaxis" (DDP) has now indeed been demonstrated experimentally in several species. However, it remains unclear how DDP will affect the population dynamics of the host-pathogen interaction, with previous theoretical work making conflicting predictions. We develop a general host-pathogen model and assess the role of DDP on the population dynamics. The ability of DDP to drive population cycles is critically dependent on the time delay between the change in density and the subsequent phenotypic change in the level of resistance. When the delay is absent or short, DDP destabilises the system. As the delay increases, its destabilising effect first diminishes and then DDP becomes increasingly stabilising. Our work highlights the significance of the time delay and suggests that it must be estimated experimentally or varied in theoretical investigations in order to understand the implications of DDP for the population dynamics of particular systems.

  16. Child Marriage, Agency, and Schooling in Rural Honduras

    Science.gov (United States)

    Murphy-Graham, Erin; Leal, Graciela

    2015-01-01

    This article examines the relationships between child marriage, agency, and schooling in rural Honduras. Through an in-depth qualitative case study, we address the following questions: (1) In what ways, if any, do girls exercise agency in their decision to marry? (2) How might education enhance girls' agency, expanding their choice sets and…

  17. First report of "Candidatus Liberibacter solanacearum" infecting eggplant in Honduras

    Science.gov (United States)

    In May of 2012, eggplant (Solanum melongena) plants in an experimental research plot located at Zamorano in the Department of Francisco Morazán, Honduras, were observed with symptoms that included leaf chlorosis and cupping, overall stunting, and production of small and malformed fruits. The researc...

  18. First report of "Candidatus Liberibacter solanacearum" on pepper in Honduras

    Science.gov (United States)

    In 2012, bell pepper (Capsicum annuum) plants exhibiting symptoms that resembled those of the bacterium “Candidatus Liberibacter solanacearum” infection were observed in commercial pepper fields in several departments in Honduras, including Francisco Morazán, Ocotepeque, El Paraíso, and Olancho. Man...

  19. Forest management in Bolivia, Honduras and Nicaragua : reform failures?

    NARCIS (Netherlands)

    L. Pellegrini (Lorenzo)

    2009-01-01

    textabstractIn this study we contrast forestry reforms and their stated objectives against the state of the forestry sector in Bolivia, Honduras and Nicaragua. Once we look at the policy failures that underlie the gap between policy objectives and the state of forestry, we find that stated policies

  20. Social Integration and Health Behavioral Change in San Luis, Honduras

    Science.gov (United States)

    McQuestion, Michael J.; Calle, Ana Quijano; Drasbek, Christopher; Harkins, Thomas; Sagastume, Lourdes J.

    2010-01-01

    This study explores the effects of social integration on behavioral change in the course of an intensive, community-based public health intervention. The intervention trained volunteers and mobilized local organizations to promote 16 key family health practices in rural San Luis, Honduras, during 2004 to 2006. A mixed methods approach is used.…

  1. Forest management in Bolivia, Honduras and Nicaragua: reform failures?

    NARCIS (Netherlands)

    L. Pellegrini (Lorenzo)

    2010-01-01

    textabstractThis study is a policy assessment contrasting forestry reforms and their intended objectives against the state of the forestry sector in Bolivia, Honduras and Nicaragua. The study finds that there is a gap between policy objectives and the state of forestry in the three countries, and th

  2. Anthracnose disease evaluation of sorghum germplasm from Honduras

    Science.gov (United States)

    Germplasm collections are important resources for sorghum improvement and 17 accessions from Honduras were inoculated with Colletotrichum sublineolum and evaluated at the Tropical Agriculture Research Station in Isabela, Puerto Rico during the 2005 and 2006 growing seasons to identify sources of ant...

  3. A provisional annotated list of the Lepidoptera of Honduras

    Science.gov (United States)

    A biodiversity inventory of the Lepidoptera of Pico Bonito National Park and vicinity, in the Department of Atlantida of northern Honduras, has been initiated and will be conducted to obtain baseline data. We present a revised checklist of Honduran butterfly species (updated from the initial 1967 l...

  4. First report of 'Candidatus Liberibacter solanacearum' on tomato in Honduras

    Science.gov (United States)

    In April of 2012, tomato plants grown in several departments of Honduras, were observed with symptoms resembling those of “Candidatus Liberibacter solanacearum” (Lso) infection. The symptoms include overall chlorosis, severe stunting, leaf cupping, excessive branching of axillary shoots, and leaf pu...

  5. A new species of Poecilia from Honduras (Teleostei: Poeciliidae)

    NARCIS (Netherlands)

    F.N. Poeser

    2011-01-01

    A new species of Poecilia from the Atlantic slopes of Honduras is described and assigned to the subgenus Mollienesia. Poecilia hondurensis, new species, differs from all congeners in the combination of having tricuspid teeth on the inner of both jaws and lacking a prominent spine or hook on the gono

  6. Political ecology, mountain agriculture, and knowledge in Honduras

    NARCIS (Netherlands)

    Jansen, K.

    1998-01-01

    The social and biophysical processes entailed in environmental deterioration are the subject of intense debate in Honduras, one of the poorest countries of Latin America. This book analyses the political ecology of precarious farming in mountainous areas. The author evaluates a rich array

  7. Political ecology, mountain agriculture, and knowledge in Honduras.

    NARCIS (Netherlands)

    Jansen, K.

    1998-01-01

    The social and biophysical processes entailed in environmental deterioration are the subject of intense debate in Honduras, one of the poorest countries of Latin America. This book analyses the political ecology of precarious farming in mountainous areas. The author evaluates a rich array of social

  8. Latin American 24/7 News Battle for Honduras

    National Research Council Canada - National Science Library

    Claudia Boyd-Barrett; Oliver Boyd-Barrett

    2010-01-01

    ...), NTN24 (based in Bogota, Colombia) and TeleSur (based in Caracas, Venezuela) during the first days of the aftermath of a coup in Honduras at the end of June 2009, which forcibly removed President Manuel Zelaya from office. The results, largely confirming those of the authors' earlier analysis of how these channels covered 2009 riots in Iran an...

  9. Stochastic population dynamics in populations of western terrestrial garter snakes with divergent life histories.

    Science.gov (United States)

    Miller, David A; Clark, William R; Arnold, Stevan J; Bronikowski, Anne M

    2011-08-01

    Comparative evaluations of population dynamics in species with temporal and spatial variation in life-history traits are rare because they require long-term demographic time series from multiple populations. We present such an analysis using demographic data collected during the interval 1978-1996 for six populations of western terrestrial garter snakes (Thamnophis elegans) from two evolutionarily divergent ecotypes. Three replicate populations from a slow-living ecotype, found in mountain meadows of northeastern California, were characterized by individuals that develop slowly, mature late, reproduce infrequently with small reproductive effort, and live longer than individuals of three populations of a fast-living ecotype found at lakeshore locales. We constructed matrix population models for each of the populations based on 8-13 years of data per population and analyzed both deterministic dynamics based on mean annual vital rates and stochastic dynamics incorporating annual variation in vital rates. (1) Contributions of highly variable vital rates to fitness (lambda(s)) were buffered against the negative effects of stochastic variation, and this relationship was consistent with differences between the meadow (M-slow) and lakeshore (L-fast) ecotypes. (2) Annual variation in the proportion of gravid females had the greatest negative effect among all vital rates on lambda(s). The magnitude of variation in the proportion of gravid females and its effect on lambda(s) was greater in M-slow than L-fast populations. (3) Variation in the proportion of gravid females, in turn, depended on annual variation in prey availability, and its effect on lambda(s) was 4 23 times greater in M-slow than L-fast populations. In addition to differences in stochastic dynamics between ecotypes, we also found higher mean mortality rates across all age classes in the L-fast populations. Our results suggest that both deterministic and stochastic selective forces have affected the evolution of

  10. Stochastic population dynamics in populations of western terrestrial garter snakes with divergent life histories

    Science.gov (United States)

    Miller, David A.; Clark, W.R.; Arnold, S.J.; Bronikowski, A.M.

    2011-01-01

    Comparative evaluations of population dynamics in species with temporal and spatial variation in life-history traits are rare because they require long-term demographic time series from multiple populations. We present such an analysis using demographic data collected during the interval 1978-1996 for six populations of western terrestrial garter snakes (Thamnophis elegans) from two evolutionarily divergent ecotypes. Three replicate populations from a slow-living ecotype, found in mountain meadows of northeastern California, were characterized by individuals that develop slowly, mature late, reproduce infrequently with small reproductive effort, and live longer than individuals of three populations of a fast-living ecotype found at lakeshore locales. We constructed matrix population models for each of the populations based on 8-13 years of data per population and analyzed both deterministic dynamics based on mean annual vital rates and stochastic dynamics incorporating annual variation in vital rates. (1) Contributions of highly variable vital rates to fitness (??s) were buffered against the negative effects of stochastic variation, and this relationship was consistent with differences between the meadow (M-slow) and lakeshore (L-fast) ecotypes. (2) Annual variation in the proportion of gravid females had the greatest negative effect among all vital rates on ?? s. The magnitude of variation in the proportion of gravid females and its effect on ??s was greater in M-slow than L-fast populations. (3) Variation in the proportion of gravid females, in turn, depended on annual variation in prey availability, and its effect on ??s was 4- 23 times greater in M-slow than L-fast populations. In addition to differences in stochastic dynamics between ecotypes, we also found higher mean mortality rates across all age classes in the L-fast populations. Our results suggest that both deterministic and stochastic selective forces have affected the evolution of divergent life

  11. Climate change impacts on maize and dry bean yields of smallholder farmers in Honduras

    Directory of Open Access Journals (Sweden)

    MENDOZA, Carlos O.

    2013-06-01

    Full Text Available The rotation maize and dry bean provides the main food supply of smallholder farmers in Honduras. Crop model assessment of climate change impacts (2070–2099 compared to a 1961–1990 baseline on a maize–dry bean rotation for several sites across a range of climatic zones and elevations in Honduras. Low productivity systems, together with an uncertain future climate, pose a high level of risk for food security. The cropping systems simulation dynamic model CropSyst was calibrated and validated upon field trail site at Zamorano, then run with baseline and future climate scenarios based upon general circulation models (GCM and the ClimGen synthetic daily weather generator. Results indicate large uncertainty in crop production from various GCM simulations and future emissions scenarios, but generally reduced yields at low elevations by 0 % to 22 % in suitable areas for crop production and increased yield at the cooler, on the hillsides, where farming needs to reduce soil erosion with conservation techniques. Further studies are needed to investigate strategies to reduce impacts and to explore adaptation tactics.

  12. Honduras: nuevo gobierno liberal con la misma agenda política

    Directory of Open Access Journals (Sweden)

    Natalia Ajenjo Fresno

    2007-01-01

    Full Text Available El artículo presenta brevemente los eventos más relevantes ocurridos en Honduras en el periodo 2005, desde la celebración de las elecciones presidenciales y legislativas hasta la actualidad. El texto sostiene fundamentalmente que el 2005 como año electoral ha supuesto una combinación de cambio y continuidad importante, y por tanto examina la dosis de esta combinación. En particular, presta atención a los cambios de funcionamiento electoral, que sin embargo no han afectado la dinámica política de forma visible ni en relación a la agenda política de gobierno ni al contexto de gobierno unificado que garantiza el apoyo a éstaThe article briefly presents the most relevant facts occurred in Honduras in the period from 2005, when the presidential and legislative elections took place, until nowadays. The text basically posits the 2005 as an electoral year where change and continuity have been intertwined and thus pays attention to the doses of such interaction. In particular, the article focuses on the changes in the electoral rules governing the election, which in turn have not visibly affected the political dynamics, neither concerning the agenda of the government nor the context of unified government which ensures the support to this agenda

  13. Drug consumption by medical students in tegucigalpa, Honduras Uso de drogas entre estudiantes de medicina, tegucigalpa, Honduras O uso de drogas entre estudantes de medicina em tegucigalpa, Honduras

    OpenAIRE

    2008-01-01

    The use of drugs, in Honduras, involves 25% of college students. The most used substances include legal and recreational drugs, such as alcohol. This study aimed to identify the use of drugs and socio-demographic factors in a sample of 260 medical students. RESULTS: Average age of 20 years old, unemployed and religious women, single, with no children. Alcohol was the most consumed drug in the last six months for recreational purposes. The following stimulants were frequently consumed: caffein...

  14. How predation and landscape fragmentation affect vole population dynamics

    DEFF Research Database (Denmark)

    Dalkvist, Trine; Sibly, Richard; Topping, Christopher John

    2011-01-01

    on vole population dynamics of making predators more specialised, of altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation...... to unravel in field experiments. We hope our results will help understand the reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered...

  15. How Predation and Landscape Fragmentation Affect Vole Population Dynamics

    DEFF Research Database (Denmark)

    Dalkvist, Trine; Sibly, Richard M.; Topping, Chris J.

    2011-01-01

    on vole population dynamics of making predators more specialised, of altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation...... to unravel in field experiments. We hope our results will help understand the reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered...

  16. Disentangling seasonal bacterioplankton population dynamics by high-frequency sampling.

    Science.gov (United States)

    Lindh, Markus V; Sjöstedt, Johanna; Andersson, Anders F; Baltar, Federico; Hugerth, Luisa W; Lundin, Daniel; Muthusamy, Saraladevi; Legrand, Catherine; Pinhassi, Jarone

    2015-07-01

    Multiyear comparisons of bacterioplankton succession reveal that environmental conditions drive community shifts with repeatable patterns between years. However, corresponding insight into bacterioplankton dynamics at a temporal resolution relevant for detailed examination of variation and characteristics of specific populations within years is essentially lacking. During 1 year, we collected 46 samples in the Baltic Sea for assessing bacterial community composition by 16S rRNA gene pyrosequencing (nearly twice weekly during productive season). Beta-diversity analysis showed distinct clustering of samples, attributable to seemingly synchronous temporal transitions among populations (populations defined by 97% 16S rRNA gene sequence identity). A wide spectrum of bacterioplankton dynamics was evident, where divergent temporal patterns resulted both from pronounced differences in relative abundance and presence/absence of populations. Rates of change in relative abundance calculated for individual populations ranged from 0.23 to 1.79 day(-1) . Populations that were persistently dominant, transiently abundant or generally rare were found in several major bacterial groups, implying evolution has favoured a similar variety of life strategies within these groups. These findings suggest that high temporal resolution sampling allows constraining the timescales and frequencies at which distinct populations transition between being abundant or rare, thus potentially providing clues about physical, chemical or biological forcing on bacterioplankton community structure.

  17. Population dynamic theory of size-dependent cannibalism.

    Science.gov (United States)

    Claessen, David; de Roos, André M.; Persson, Lennart

    2004-01-01

    Cannibalism is characterized by four aspects: killing victims, gaining energy from victims, size-dependent interactions and intraspecific competition. In this review of mathematical models of cannibalistic populations, we relate the predicted population dynamic consequences of cannibalism to its four defining aspects. We distinguish five classes of effects of cannibalism: (i) regulation of population size; (ii) destabilization resulting in population cycles or chaos; (iii) stabilization by damping population cycles caused by other interactions; (iv) bistability such that, depending on the initial conditions, the population converges to one of two possible stable states; and (v) modification of the population size structure. The same effects of cannibalism may be caused by different combinations of aspects of cannibalism. By contrast, the same combination of aspects may lead to different effects. For particular cannibalistic species, the consequences of cannibalism will depend on the presence and details of the four defining aspects. Empirical evidence for the emerged theory of cannibalism is discussed briefly. The implications of the described dynamic effects of cannibalism are discussed in the context of community structure, making a comparison with the community effects of intraguild predation. PMID:15101690

  18. Binary Populations and Stellar Dynamics in Young Clusters

    Science.gov (United States)

    Vanbeveren, D.; Belkus, H.; Van Bever, J.; Mennekens, N.

    2008-06-01

    We first summarize work that has been done on the effects of binaries on theoretical population synthesis of stars and stellar phenomena. Next, we highlight the influence of stellar dynamics in young clusters by discussing a few candidate UFOs (unconventionally formed objects) like intermediate mass black holes, η Car, ζ Pup, γ2 Velorum and WR 140.

  19. Network evolution induced by the dynamical rules of two populations

    Science.gov (United States)

    Platini, Thierry; Zia, R. K. P.

    2010-10-01

    We study the dynamical properties of a finite dynamical network composed of two interacting populations, namely extrovert (a) and introvert (b). In our model, each group is characterized by its size (Na and Nb) and preferred degree (κa and \\kappa_b\\ll \\kappa_a ). The network dynamics is governed by the competing microscopic rules of each population that consist of the creation and destruction of links. Starting from an unconnected network, we give a detailed analysis of the mean field approach which is compared to Monte Carlo simulation data. The time evolution of the restricted degrees langkbbrang and langkabrang presents three time regimes and a non-monotonic behavior well captured by our theory. Surprisingly, when the population sizes are equal Na = Nb, the ratio of the restricted degree θ0 = langkabrang/langkbbrang appears to be an integer in the asymptotic limits of the three time regimes. For early times (defined by t introverts remains constant while the number of connections increases linearly in the extrovert population. Finally, due to the competing dynamics, the network presents a frustrated stationary state characterized by a ratio θ0 = 3.

  20. Population dynamics of light-limited phytoplankton : Microcosm experiments

    NARCIS (Netherlands)

    Huisman, Jef

    This paper investigates the extent to which the predictions of an elementary model for light-limited growth are matched by laboratory experiments with light-limited phytoplankton. The model and experiments link the population dynamics of phytoplankton species with changes in the light gradient

  1. Equilibrium solutions for microscopic stochastic systems in population dynamics.

    Science.gov (United States)

    Lachowicz, Mirosław; Ryabukha, Tatiana

    2013-06-01

    The present paper deals with the problem of existence of equilibrium solutions of equations describing the general population dynamics at the microscopic level of modified Liouville equation (individually--based model) corresponding to a Markov jump process. We show the existence of factorized equilibrium solutions and discuss uniqueness. The conditions guaranteeing uniqueness or non-uniqueness are proposed under the assumption of periodic structures.

  2. Do farming practices influence population dynamics of rodents?

    DEFF Research Database (Denmark)

    Massawe, A W; Rwamugira, W; Leirs, Herwig

    2007-01-01

    and slash and burn fields, cropping systems (mono- and inter-crop) had little effect on the population dynamics of M. natalensis [F(1,8) = 6.50; P > 0.05]. The study shows that land preparation methods should be considered a component of rodent pest management in ecologically based or integrated management...

  3. Binary populations and stellar dynamics in young clusters

    CERN Document Server

    Vanbeveren, D; Van Bever, J; Mennekens, N

    2008-01-01

    We first summarize work that has been done on the effects of binaries on theoretical population synthesis of stars and stellar phenomena. Next, we highlight the influence of stellar dynamics in young clusters by discussing a few candidate UFOs (unconventionally formed objects) like intermediate mass black holes, Eta Carinae, Zeta Puppis, Gamma Velorum and WR 140.

  4. Distribution and population dynamics of Rhizobium sp. introduced into soil.

    NARCIS (Netherlands)

    Postma, J.

    1989-01-01

    In this thesis the population dynamics of bacteria introduced into soil was studied. In the introduction, the existence of microhabitats favourable for the survival of indigenous bacteria is discussed. Knowledge about the distribution of introduced bacteria over such microhabitats,

  5. COMPARISON OF SAMPLING TECHNIQUES USED IN STUDYING LEPIDOPTERA POPULATION DYNAMICS

    Science.gov (United States)

    Four methods (light traps, foliage samples, canvas bands, and gypsy moth egg mass surveys) that are used to study the population dynamics of foliage-feeding Lepidoptera were compared for 10 species, including gypsy moth, Lymantria dispar L. Samples were collected weekly at 12 sit...

  6. Stochastic simulation of HIV population dynamics through complex network modelling

    NARCIS (Netherlands)

    Sloot, P.M.A.; Ivanov, S.V.; Boukhanovsky, A.V.; van de Vijver, D.A.M.C.; Boucher, C.A.B.

    2008-01-01

    We propose a new way to model HIV infection spreading through the use of dynamic complex networks. The heterogeneous population of HIV exposure groups is described through a unique network degree probability distribution. The time evolution of the network nodes is modelled by a Markov process and

  7. Stochastic simulation of HIV population dynamics through complex network modelling

    NARCIS (Netherlands)

    Sloot, P. M. A.; Ivanov, S. V.; Boukhanovsky, A. V.; van de Vijver, D. A. M. C.; Boucher, C. A. B.

    We propose a new way to model HIV infection spreading through the use of dynamic complex networks. The heterogeneous population of HIV exposure groups is described through a unique network degree probability distribution. The time evolution of the network nodes is modelled by a Markov process and

  8. Distribution and population dynamics of Rhizobium sp. introduced into soil

    NARCIS (Netherlands)

    Postma, J.

    1989-01-01

    In this thesis the population dynamics of bacteria introduced into soil was studied. In the introduction, the existence of microhabitats favourable for the survival of indigenous bacteria is discussed. Knowledge about the distribution of introduced bacteria over

  9. Population dynamics of light-limited phytoplankton : Microcosm experiments

    NARCIS (Netherlands)

    Huisman, Jef

    1999-01-01

    This paper investigates the extent to which the predictions of an elementary model for light-limited growth are matched by laboratory experiments with light-limited phytoplankton. The model and experiments link the population dynamics of phytoplankton species with changes in the light gradient cause

  10. Population Receptive Field Dynamics in Human Visual Cortex

    NARCIS (Netherlands)

    Haak, Koen V.; Cornelissen, Frans W.; Morland, Antony B.

    2012-01-01

    Seminal work in the early nineties revealed that the visual receptive field of neurons in cat primary visual cortex can change in location and size when artificial scotomas are applied. Recent work now suggests that these single neuron receptive field dynamics also pertain to the neuronal population

  11. Neuronal population dynamic model:An analytic approach

    Institute of Scientific and Technical Information of China (English)

    Wentao Huang; Licheng Jiao; Yuelei Xu; Shiping Ma; Jianhua Jia

    2009-01-01

    rom this,the stationary solution and the firing rate of the stationary states are given.Last,by the Fourier transform,the time dependent solution is also obtained.This method can be used to analyze the various dynamic behaviors of neuronal populations.

  12. Dynamics of adaptive immunity against phage in bacterial populations

    CERN Document Server

    Bradde, Serena; Tesileanu, Tiberiu; Balasubramanian, Vijay

    2015-01-01

    The CRISPR (clustered regularly interspaced short palindromic repeats) mechanism allows bacteria to adaptively defend against phages by acquiring short genomic sequences (spacers) that target specific sequences in the viral genome. We propose a population dynamical model where immunity can be both acquired and lost. The model predicts regimes where bacterial and phage populations can co-exist, others where the populations oscillate, and still others where one population is driven to extinction. Our model considers two key parameters: (1) ease of acquisition and (2) spacer effectiveness in conferring immunity. Analytical calculations and numerical simulations show that if spacers differ mainly in ease of acquisition, or if the probability of acquiring them is sufficiently high, bacteria develop a diverse population of spacers. On the other hand, if spacers differ mainly in their effectiveness, their final distribution will be highly peaked, akin to a "winner-take-all" scenario, leading to a specialized spacer ...

  13. Primary care provision by volunteer medical brigades in Honduras: a health record review of more than 2,500 patients over three years.

    Science.gov (United States)

    Martiniuk, Alexandra L C; Adunuri, Nikesh; Negin, Joel; Tracey, Patti; Fontecha, Claudio; Caldwell, Paul

    2012-01-01

    The weak health system in Honduras contributes to poor health indicators. To improve population health, a number of volunteer medical brigades from developed countries provide health services in Honduras. To date, there is little information on the brigades' activities and impact. The primary objective of this article is to increase understanding of the type of health care provided by voluntary medical brigades by evaluating and presenting data on patients' presenting symptoms, diagnoses, and care outcomes. The article focuses on an ongoing medical brigade organized by Canadian health professionals in conjunction with Honduras' largest national non-governmental organization. This is a descriptive study of data that are routinely collected by volunteer Canadian health care professionals. Data on all patients presenting to temporary primary health care facilities across Honduras between 2006 and 2009 were analyzed. The data were used to analyze patient demographics, presenting symptoms, diagnoses, and treatments. We found that the brigades provide additional human resources to the relatively weak Honduran health care system. However, while brigades may increase solidarity between Hondurans and Canadians, concerns persist regarding cost-effectiveness and continuity of care for conditions treated by short-term brigade volunteers. Greater scrutiny is needed to increase brigades' effectiveness and ensure they are supportive of domestic health systems.

  14. Population dynamics and mutualism: Functional responses of benefits and costs

    Science.gov (United States)

    Holland, J. Nathaniel; DeAngelis, Donald L.; Bronstein, Judith L.

    2002-01-01

    We develop an approach for studying population dynamics resulting from mutualism by employing functional responses based on density‐dependent benefits and costs. These functional responses express how the population growth rate of a mutualist is modified by the density of its partner. We present several possible dependencies of gross benefits and costs, and hence net effects, to a mutualist as functions of the density of its partner. Net effects to mutualists are likely a monotonically saturating or unimodal function of the density of their partner. We show that fundamental differences in the growth, limitation, and dynamics of a population can occur when net effects to that population change linearly, unimodally, or in a saturating fashion. We use the mutualism between senita cactus and its pollinating seed‐eating moth as an example to show the influence of different benefit and cost functional responses on population dynamics and stability of mutualisms. We investigated two mechanisms that may alter this mutualism's functional responses: distribution of eggs among flowers and fruit abortion. Differences in how benefits and costs vary with density can alter the stability of this mutualism. In particular, fruit abortion may allow for a stable equilibrium where none could otherwise exist.

  15. Evolutionary dynamics of group interactions on structured populations: A review

    CERN Document Server

    Perc, Matjaz; Szolnoki, Attila; Floría, Luis M; Moreno, Yamir; 10.1098/rsif.2012.0997

    2013-01-01

    Interactions among living organisms, from bacteria colonies to human societies, are inherently more complex than interactions among particles and nonliving matter. Group interactions are a particularly important and widespread class, representative of which is the public goods game. In addition, methods of statistical physics have proven valuable for studying pattern formation, equilibrium selection, and self-organisation in evolutionary games. Here we review recent advances in the study of evolutionary dynamics of group interactions on structured populations, including lattices, complex networks and coevolutionary models. We also compare these results with those obtained on well-mixed populations. The review particularly highlights that the study of the dynamics of group interactions, like several other important equilibrium and non-equilibrium dynamical processes in biological, economical and social sciences, benefits from the synergy between statistical physics, network science and evolutionary game theory...

  16. Nonequilibrium population dynamics of phenotype conversion of cancer cells.

    Directory of Open Access Journals (Sweden)

    Joseph Xu Zhou

    Full Text Available Tumorigenesis is a dynamic biological process that involves distinct cancer cell subpopulations proliferating at different rates and interconverting between them. In this paper we proposed a mathematical framework of population dynamics that considers both distinctive growth rates and intercellular transitions between cancer cell populations. Our mathematical framework showed that both growth and transition influence the ratio of cancer cell subpopulations but the latter is more significant. We derived the condition that different cancer cell types can maintain distinctive subpopulations and we also explain why there always exists a stable fixed ratio after cell sorting based on putative surface markers. The cell fraction ratio can be shifted by changing either the growth rates of the subpopulations (Darwinism selection or by environment-instructed transitions (Lamarckism induction. This insight can help us to understand the dynamics of the heterogeneity of cancer cells and lead us to new strategies to overcome cancer drug resistance.

  17. Understanding diabetes population dynamics through simulation modeling and experimentation.

    Science.gov (United States)

    Jones, Andrew P; Homer, Jack B; Murphy, Dara L; Essien, Joyce D K; Milstein, Bobby; Seville, Donald A

    2006-03-01

    Health planners in the Division of Diabetes Translation and others from the National Center for Chronic Disease Prevention and Health Promotion of the Centers for Disease Control and Prevention used system dynamics simulation modeling to gain a better understanding of diabetes population dynamics and to explore implications for public health strategy. A model was developed to explain the growth of diabetes since 1980 and portray possible futures through 2050. The model simulations suggest characteristic dynamics of the diabetes population, including unintended increases in diabetes prevalence due to diabetes control, the inability of diabetes control efforts alone to reduce diabetes-related deaths in the long term, and significant delays between primary prevention efforts and downstream improvements in diabetes outcomes.

  18. Within- and among-population variation in vital rates and population dynamics in a variable environment.

    Science.gov (United States)

    Vincenzi, Simone; Mangel, Marc; Jesensˇek, Dusˇan; Garza, John C; Crivelli, Alain J

    2016-10-01

    Understanding the causes of within- and among-population differences in vital rates, life histories, and population dynamics is a central topic in ecology. To understand how within- and among-population variation emerges, we need long-term studies that include episodic events and contrasting environmental conditions, data to characterize individual and shared variation, and statistical models that can tease apart shared and individual contribution to the observed variation. We used long-term tag-recapture data to investigate and estimate within- and among-population differences in vital rates, life histories, and population dynamics of marble trout Salmo marmoratus, an endemic freshwater salmonid with a narrow range. Only ten populations of pure marble trout persist in headwaters of Alpine rivers in western Slovenia. Marble trout populations are also threatened by floods and landslides, which have already caused the extinction of two populations in recent years. We estimated and determined causes of variation in growth, survival, and recruitment both within and among populations, and evaluated trade-offs between them. Specifically, we estimated the responses of these traits to variation in water temperature, density, sex, early life conditions, and extreme events. We found that the effects of population density on traits were mostly limited to the early stages of life and that growth trajectories were established early in life. We found no clear effects of water temperature on vital rates. Population density varied over time, with flash floods and debris flows causing massive mortalities (>55% decrease in survival with respect to years with no floods) and threatening population persistence. Apart from flood events, variation in population density within streams was largely determined by variation in recruitment, with survival of older fish being relatively constant over time within populations, but substantially different among populations. Marble trout show a fast

  19. Estimating spatio-temporal dynamics of size-structured populations

    DEFF Research Database (Denmark)

    Kristensen, Kasper; Thygesen, Uffe Høgsbro; Andersen, Ken Haste

    2014-01-01

    Spatial distributions of structured populations are usually estimated by fitting abundance surfaces for each stage and at each point of time separately, ignoring correlations that emerge from growth of individuals. Here, we present a statistical model that combines spatio-temporal correlations...... with simple stock dynamics, to estimate simultaneously how size distributions and spatial distributions develop in time. We demonstrate the method for a cod population sampled by trawl surveys. Particular attention is paid to correlation between size classes within each trawl haul due to clustering...... of individuals with similar size. The model estimates growth, mortality and reproduction, after which any aspect of size-structure, spatio-temporal population dynamics, as well as the sampling process can be probed. This is illustrated by two applications: 1) tracking the spatial movements of a single cohort...

  20. Past and present population dynamics of narwhals Monodon monoceros

    DEFF Research Database (Denmark)

    Garde, Eva

    , meat and mattak. Concerns have been raised about the sustainability of the hunt, which have led to implementation of hunting quotas in both countries. Hunting quotas are usually calculated from population dynamics models where survival and reproductive rates, based on reliable age distributions......, are vital. Estimation of life history parameters for the narwhal has previously been hindered by lack of a reliable age estimation technique. The Aspartic Acid Racemization (AAR) technique is a relatively novel method that I have applied to narwhals. This PhD thesis focuses, in part, on current population...... of both marine and terrestrial mammals, although the technique still requires both optimization and further validation. In addition, the thesis includes a study of past population dynamics in narwhals. We have investigated the genetic response to climate change and the emographic history of the narwhal...

  1. Rethinking the logistic approach for population dynamics of mutualistic interactions.

    Science.gov (United States)

    García-Algarra, Javier; Galeano, Javier; Pastor, Juan Manuel; Iriondo, José María; Ramasco, José J

    2014-12-21

    Mutualistic communities have an internal structure that makes them resilient to external perturbations. Late research has focused on their stability and the topology of the relations between the different organisms to explain the reasons of the system robustness. Much less attention has been invested in analyzing the systems dynamics. The main population models in use are modifications of the r-K formulation of logistic equation with additional terms to account for the benefits produced by the interspecific interactions. These models have shortcomings as the so-called r-K formulation diverges under some conditions. In this work, we introduce a model for population dynamics under mutualism that preserves the original logistic formulation. It is mathematically simpler than the widely used type II models, although it shows similar complexity in terms of fixed points and stability of the dynamics. We perform an analytical stability analysis and numerical simulations to study the model behavior in general interaction scenarios including tests of the resilience of its dynamics under external perturbations. Despite its simplicity, our results indicate that the model dynamics shows an important richness that can be used to gain further insights in the dynamics of mutualistic communities.

  2. Modeling structured population dynamics using data from unmarked individuals

    Science.gov (United States)

    Grant, Evan H. Campbell; Zipkin, Elise; Thorson, James T.; See, Kevin; Lynch, Heather J.; Kanno, Yoichiro; Chandler, Richard; Letcher, Benjamin H.; Royle, J. Andrew

    2014-01-01

    The study of population dynamics requires unbiased, precise estimates of abundance and vital rates that account for the demographic structure inherent in all wildlife and plant populations. Traditionally, these estimates have only been available through approaches that rely on intensive mark–recapture data. We extended recently developed N-mixture models to demonstrate how demographic parameters and abundance can be estimated for structured populations using only stage-structured count data. Our modeling framework can be used to make reliable inferences on abundance as well as recruitment, immigration, stage-specific survival, and detection rates during sampling. We present a range of simulations to illustrate the data requirements, including the number of years and locations necessary for accurate and precise parameter estimates. We apply our modeling framework to a population of northern dusky salamanders (Desmognathus fuscus) in the mid-Atlantic region (USA) and find that the population is unexpectedly declining. Our approach represents a valuable advance in the estimation of population dynamics using multistate data from unmarked individuals and should additionally be useful in the development of integrated models that combine data from intensive (e.g., mark–recapture) and extensive (e.g., counts) data sources.

  3. The population dynamics of an endemic collectible cactus

    Science.gov (United States)

    Mandujano, María C.; Bravo, Yolotzin; Verhulst, Johannes; Carrillo-Angeles, Israel; Golubov, Jordan

    2015-02-01

    Astrophytum is one of most collected genera in the cactus family. Around the world several species are maintained in collections and yearly, several plants are taken from their natural habitats. Populations of Astorphytum capricorne are found in the northern Chihuahuan desert, Mexico, and as many endemic cactus species, it has a highly restricted habitat. We conducted a demographic study from 2008 to 2010 of the northern populations found at Cuatro Ciénegas, Mexico. We applied matrix population models, included simulations, life table response experiments and descriptions of the population dynamics to evaluate the current status of the species, and detect key life table stages and demographic processes. Population growth rate decreased in both years and only 4% individual mortality can be attributed to looting, and a massive effort is needed to increase seedling recruitment and reduce adult mortality. The fate of individuals differed between years even having the same annual rainfall mainly in accentuated stasis, retrogression and high mortality in all size classes, which coupled with low seed production, no recruitment and collection of plants are the causes contributing to population decline, and hence, increase the risk in which A. capricorne populations are found. Reintroduction of seedlings and lowering adult mortality are urgently needed to revert the alarming demographic condition of A. capricorne populations.

  4. Population dynamics in Er3+-doped fluoride glasses

    Science.gov (United States)

    Bogdanov, V. K.; Booth, D. J.; Gibbs, W. E.; Javorniczky, J. S.; Newman, P. J.; Macfarlane, D. R.

    2001-05-01

    A detailed study of the energy-transfer processes in Er3+: flouride glasses with doping concentrations of 0.2-18 mol % is presented. Fluorescence wave forms for 11 erbium transitions were measured under 802-nm, 1.5-μm, 975-nm, 520-nm, and 403-nm excitation from a high-energy short-pulse source. The analysis of these data provided a physical understanding of the processes responsible for the temporal behavior of the populations of a large number of energy levels. A comprehensive nine-level rate-equation model of the Er3+ population dynamics in these fluoride glasses is developed. The model performs well in predicting the observed fluorescence behavior of the main fluorescing lines under all pumping conditions. The modeling process allowed 14 ion-ion energy-transfer processes that are important for the population dynamics in these fluoride glasses to be identified and their rate constants obtained. Noticeably, the inclusion of seven three-ion processes was found necessary in order to obtain good fits to the experimental fluorescence wave forms. It was also found that some three-ion processes have a significant effect on the population dynamics of the levels even in lower doping concentrations.

  5. Changes in population dynamics in mutualistic versus pathogenic viruses.

    Science.gov (United States)

    Roossinck, Marilyn J

    2011-01-01

    Although generally regarded as pathogens, viruses can also be mutualists. A number of examples of extreme mutualism (i.e., symbiogenesis) have been well studied. Other examples of mutualism are less common, but this is likely because viruses have rarely been thought of as having any beneficial effects on their hosts. The effect of mutualism on the population dynamics of viruses is a topic that has not been addressed experimentally. However, the potential for understanding mutualism and how a virus might become a mutualist may be elucidated by understanding these dynamics.

  6. Changes in Population Dynamics in Mutualistic versus Pathogenic Viruses

    Directory of Open Access Journals (Sweden)

    Marilyn J. Roossinck

    2011-01-01

    Full Text Available Although generally regarded as pathogens, viruses can also be mutualists. A number of examples of extreme mutualism (i.e., symbiogenesis have been well studied. Other examples of mutualism are less common, but this is likely because viruses have rarely been thought of as having any beneficial effects on their hosts. The effect of mutualism on the population dynamics of viruses is a topic that has not been addressed experimentally. However, the potential for understanding mutualism and how a virus might become a mutualist may be elucidated by understanding these dynamics.

  7. Assessing tiger population dynamics using photographic capture-recapture sampling

    Science.gov (United States)

    Karanth, K.U.; Nichols, J.D.; Kumar, N.S.; Hines, J.E.

    2006-01-01

    Although wide-ranging, elusive, large carnivore species, such as the tiger, are of scientific and conservation interest, rigorous inferences about their population dynamics are scarce because of methodological problems of sampling populations at the required spatial and temporal scales. We report the application of a rigorous, noninvasive method for assessing tiger population dynamics to test model-based predictions about population viability. We obtained photographic capture histories for 74 individual tigers during a nine-year study involving 5725 trap-nights of effort. These data were modeled under a likelihood-based, ?robust design? capture?recapture analytic framework. We explicitly modeled and estimated ecological parameters such as time-specific abundance, density, survival, recruitment, temporary emigration, and transience, using models that incorporated effects of factors such as individual heterogeneity, trap-response, and time on probabilities of photo-capturing tigers. The model estimated a random temporary emigration parameter of =K' =Y' 0.10 ? 0.069 (values are estimated mean ? SE). When scaled to an annual basis, tiger survival rates were estimated at S = 0.77 ? 0.051, and the estimated probability that a newly caught animal was a transient was = 0.18 ? 0.11. During the period when the sampled area was of constant size, the estimated population size Nt varied from 17 ? 1.7 to 31 ? 2.1 tigers, with a geometric mean rate of annual population change estimated as = 1.03 ? 0.020, representing a 3% annual increase. The estimated recruitment of new animals, Bt, varied from 0 ? 3.0 to 14 ? 2.9 tigers. Population density estimates, D, ranged from 7.33 ? 0.8 tigers/100 km2 to 21.73 ? 1.7 tigers/100 km2 during the study. Thus, despite substantial annual losses and temporal variation in recruitment, the tiger density remained at relatively high levels in Nagarahole. Our results are consistent with the hypothesis that protected wild tiger populations can remain

  8. Optimal control methods for controlling bacterial populations with persister dynamics

    Science.gov (United States)

    Cogan, N. G.

    2016-06-01

    Bacterial tolerance to antibiotics is a well-known phenomena; however, only recent studies of bacterial biofilms have shown how multifaceted tolerance really is. By joining into a structured community and offering shared protection and gene transfer, bacterial populations can protect themselves genotypically, phenotypically and physically. In this study, we collect a line of research that focuses on phenotypic (or plastic) tolerance. The dynamics of persister formation are becoming better understood, even though there are major questions that remain. The thrust of our results indicate that even without detailed description of the biological mechanisms, theoretical studies can offer strategies that can eradicate bacterial populations with existing drugs.

  9. Integrating population dynamics into mapping human exposure to seismic hazard

    Directory of Open Access Journals (Sweden)

    S. Freire

    2012-11-01

    Full Text Available Disaster risk is not fully characterized without taking into account vulnerability and population exposure. Assessment of earthquake risk in urban areas would benefit from considering the variation of population distribution at more detailed spatial and temporal scales, and from a more explicit integration of this improved demographic data with existing seismic hazard maps. In the present work, "intelligent" dasymetric mapping is used to model population dynamics at high spatial resolution in order to benefit the analysis of spatio-temporal exposure to earthquake hazard in a metropolitan area. These night- and daytime-specific population densities are then classified and combined with seismic intensity levels to derive new spatially-explicit four-class-composite maps of human exposure. The presented approach enables a more thorough assessment of population exposure to earthquake hazard. Results show that there are significantly more people potentially at risk in the daytime period, demonstrating the shifting nature of population exposure in the daily cycle and the need to move beyond conventional residence-based demographic data sources to improve risk analyses. The proposed fine-scale maps of human exposure to seismic intensity are mainly aimed at benefiting visualization and communication of earthquake risk, but can be valuable in all phases of the disaster management process where knowledge of population densities is relevant for decision-making.

  10. Poverty-associated risk factors for wheezing in the first year of life in Honduras and El Salvador.

    Science.gov (United States)

    Bueso, A; Figueroa, M; Cousin, L; Hoyos, W; Martínez-Torres, A E; Mallol, J; Garcia-Marcos, L

    2010-01-01

    Risk factors for wheezing specifically during the first year of life have been studied in well-developed countries, but the information from developing countries is very scarce. There are no such studies focusing on factors derived from poverty. The aim of the present study was to determine if risk factors related to poverty are associated to wheezing during the first year of life in infants from Honduras and El Salvador. A survey, using a validated questionnaire, was carried out in the metropolitan area of San Pedro Sula (Honduras) and in La Libertad (El Salvador) in centres where infants attended for a scheduled vaccination shot or a healthy child visit at 12 months of age. Fieldworkers offered questionnaires to parents and helped the illiterate when necessary. The main outcome variable was wheezing during the first year of life, as reported by parents. A total of 1047 infants in El Salvador and 780 in Honduras were included in the analysis. The prevalence of wheeze in the first year was higher in El Salvador (41.2%) than in Honduras (27.7%), as was recurrent wheezing defined as three or more episodes (18.4% vs. 11.7%). Wheezing and recurrent wheezing was associated to unpaved floor in the household (summary odds ratios for both countries 1.55, p=0.036 and 1.72, p=0.054 for any wheeze and recurrent wheezing, respectively); dust entering from streets (1.30, p=0.052 and 1.67, p=0.008); living in a heavily polluted area (1.33, p=0.037 and 1.52, p=0.033); and having mould stains on the household walls (1.36, p=0.072 and 1.76, p=0.007). Furthermore, marginal associations were found for additional person at home and use of kerosene as cooking fuel. University studies in the mother (0.34, p=0.046 and 0.32, p=0.022) and a professional occupation in the father (0.34, p=0.046 and 0.26, p=0.047) were associated to a lower risk. The prevalence of wheezing and recurrent wheezing is notoriously high in El Salvador and Honduras. In those populations factors related to poverty

  11. Biology as population dynamics: heuristics for transmission risk.

    Science.gov (United States)

    Keebler, Daniel; Walwyn, David; Welte, Alex

    2013-02-01

    Population-type models, accounting for phenomena such as population lifetimes, mixing patterns, recruitment patterns, genetic evolution and environmental conditions, can be usefully applied to the biology of HIV infection and viral replication. A simple dynamic model can explore the effect of a vaccine-like stimulus on the mortality and infectiousness, which formally looks like fertility, of invading virions; the mortality of freshly infected cells; and the availability of target cells, all of which impact on the probability of infection. Variations on this model could capture the importance of the timing and duration of different key events in viral transmission, and hence be applied to questions of mucosal immunology. The dynamical insights and assumptions of such models are compatible with the continuum of between- and within-individual risks in sexual violence and may be helpful in making sense of the sparse data available on the association between HIV transmission and sexual violence. © 2012 John Wiley & Sons A/S.

  12. Effect of temperature on the population dynamics of Aedes aegypti

    Science.gov (United States)

    Yusoff, Nuraini; Tokachil, Mohd Najir

    2015-10-01

    Aedes aegypti is one of the main vectors in the transmission of dengue fever. Its abundance may cause the spread of the disease to be more intense. In the study of its biological life cycle, temperature was found to increase the development rate of each stage of this species and thus, accelerate the process of the development from egg to adult. In this paper, a Lefkovitch matrix model will be used to study the stage-structured population dynamics of Aedes aegypti. In constructing the transition matrix, temperature will be taken into account. As a case study, temperature recorded at the Subang Meteorological Station for year 2006 until 2010 will be used. Population dynamics of Aedes aegypti at maximum, average and minimum temperature for each year will be simulated and compared. It is expected that the higher the temperature, the faster the mosquito will breed. The result will be compared to the number of dengue fever incidences to see their relationship.

  13. Development of paradigms for the dynamics of structured populations

    Energy Technology Data Exchange (ETDEWEB)

    1994-10-01

    This is a technical progress report on the dynamics of predator-prey systems in a patchy environment. A new phenomenon that might contribute to outbreaks in systems of discrete patches has been determined using a discrete time model with both spatial and age structure. A model for a single species in a patchy environment with migration, local population growth and disasters with in patches has been formulated and a brief description is included.

  14. Nonlinear modeling of neural population dynamics for hippocampal prostheses

    OpenAIRE

    Song, Dong; Chan, Rosa H.M.; Vasilis Z Marmarelis; Hampson, Robert E.; Deadwyler, Sam A.; Berger, Theodore W.

    2009-01-01

    Developing a neural prosthesis for the damaged hippocampus requires restoring the transformation of population neural activities performed by the hippocampal circuitry. To bypass a damaged region, output spike trains need to be predicted from the input spike trains and then reinstated through stimulation. We formulate a multiple-input, multiple-output (MIMO) nonlinear dynamic model for the input–output transformation of spike trains. In this approach, a MIMO model comprises a series of physio...

  15. Seasonal Population Dynamics of Three Potato Pests in Washington State.

    Science.gov (United States)

    D'Auria, Elizabeth M; Wohleb, Carrie H; Waters, Timothy D; Crowder, David W

    2016-08-01

    Pest phenology models allow producers to anticipate pest outbreaks and deploy integrated pest management (IPM) strategies. Phenology models are particularly useful for cropping systems with multiple economically damaging pests throughout a season. Potato (Solanum tuberosum L.) crops of Washington State, USA, are attacked by many insect pests including the potato tuberworm (Phthorimaea operculella Zeller), the beet leafhopper (Circulifer tenellus Baker), and the green peach aphid (Myzus persicae Sulzer). Each of these pests directly damages potato foliage or tubers; C. tenellus and M. persicae also transmit pathogens that can drastically reduce potato yields. We monitored the seasonal population dynamics of these pests by conducting weekly sampling on a network of commercial farms from 2007 to 2014. Using these data, we developed phenology models to characterize the seasonal population dynamics of each pest based on accumulated degree-days (DD). All three pests exhibited consistent population dynamics across seasons that were mediated by temperature. Of the three pests, C. tenellus was generally the first detected in potato crops, with 90% of adults captured by 936 DD. In contrast, populations of P. operculella and M. persicae built up more slowly over the course of the season, with 90% cumulative catch by 1,590 and 2,634 DD, respectively. Understanding these seasonal patterns could help potato producers plan their IPM strategies while allowing them to move away from calendar-based applications of insecticides. More broadly, our results show how long-term monitoring studies that explore dynamics of multiple pest species can aid in developing IPM strategies in crop systems.

  16. Combined effect of successive competition periods on population dynamics

    OpenAIRE

    Anazawa, Masahiro

    2010-01-01

    This study investigates the effect of competition between individuals on population dynamics when they compete for different resources during different seasons or during different growth stages. Individuals are assumed to compete for a single resource during each of these periods according to one of the following competition types: scramble, contest, or an intermediate between the two. The effect of two successive competition periods is determined to be expressed by simple relations on produc...

  17. Learning to Estimate Dynamical State with Probabilistic Population Codes.

    Directory of Open Access Journals (Sweden)

    Joseph G Makin

    2015-11-01

    Full Text Available Tracking moving objects, including one's own body, is a fundamental ability of higher organisms, playing a central role in many perceptual and motor tasks. While it is unknown how the brain learns to follow and predict the dynamics of objects, it is known that this process of state estimation can be learned purely from the statistics of noisy observations. When the dynamics are simply linear with additive Gaussian noise, the optimal solution is the well known Kalman filter (KF, the parameters of which can be learned via latent-variable density estimation (the EM algorithm. The brain does not, however, directly manipulate matrices and vectors, but instead appears to represent probability distributions with the firing rates of population of neurons, "probabilistic population codes." We show that a recurrent neural network-a modified form of an exponential family harmonium (EFH-that takes a linear probabilistic population code as input can learn, without supervision, to estimate the state of a linear dynamical system. After observing a series of population responses (spike counts to the position of a moving object, the network learns to represent the velocity of the object and forms nearly optimal predictions about the position at the next time-step. This result builds on our previous work showing that a similar network can learn to perform multisensory integration and coordinate transformations for static stimuli. The receptive fields of the trained network also make qualitative predictions about the developing and learning brain: tuning gradually emerges for higher-order dynamical states not explicitly present in the inputs, appearing as delayed tuning for the lower-order states.

  18. Trends and population dynamics of a Velvet Scoter (Melanitta fusca) population: influence of density dependence and winter climate

    NARCIS (Netherlands)

    Hartman, G.; Kölzsch, A.; Larsson, K.; Nordberg, M.; Höglund, J.

    2013-01-01

    As many seaduck populations around the world have been reported to be in decline, there is an increasing demand for knowledge about intrinsic and extrinsic factors determining population dynamics of these species. In this study, we analyzed long-term dynamics of the summer population of Velvet Scote

  19. Network Evolution Induced by the Dynamical Rules of Two Populations

    CERN Document Server

    Platini, T

    2010-01-01

    We study the dynamical properties of a finite dynamical network composed of two interacting populations, namely; extrovert ($a$) and introvert ($b$). In our model, each group is characterized by its size ($N_a$ and $N_b$) and preferred degree ($\\kappa_a$ and $\\kappa_b\\ll\\kappa_a$). The network dynamics is governed by the competing microscopic rules of each population that consist of the creation and destruction of links. Starting from an unconnected network, we give a detailed analysis of the mean field approach which is compared to Monte Carlo simulation data. The time evolution of the restricted degrees $\\moyenne{k_{bb}}$ and $\\moyenne{k_{ab}}$ presents three time regimes and a non monotonic behavior well captured by our theory. Surprisingly, when the population size are equal $N_a=N_b$, the ratio of the restricted degree $\\theta_0=\\moyenne{k_{ab}}/\\moyenne{k_{bb}}$ appears to be an integer in the asymptotic limits of the three time regimes. For early times (defined by $t

  20. Pediatric convulsive status epilepticus in Honduras, Central America.

    Science.gov (United States)

    Molinero, Marco R; Holden, Kenton R; Rodriguez, Luis C; Collins, Julianne S; Samra, Jose A; Shinnar, Shlomo

    2009-10-01

    Convulsive status epilepticus (SE) in children is an important public health problem, particularly in low-resource countries. A surveillance study was performed with consecutive enrollment of all children presenting with convulsive SE to Hospital Escuela Materno-Infantil Emergency Department in Tegucigalpa, Honduras over a 13-week period in 2003. In the 47 children with SE, the mean age was 4.5 years and the median seizure duration was 95 min. Mortality and morbidity were higher in children from rural locations, with all six deaths and three cases of new neurologic abnormalities occurring in rural children who had acute symptomatic SE. We conclude that childhood SE is common in the low-resource developing country of Honduras. Given the long delays in obtaining initial treatment in pediatric emergency facilities, availability of prehospital treatment may be of particular importance in this setting.

  1. IMF shape constraints from stellar populations and dynamics from CALIFA

    CERN Document Server

    Lyubenova, M; van de Ven, G; Falcón-Barroso, J; Galbany, L; Gallazzi, A; García-Benito, R; Delgado, R González; Husemann, B; La Barbera, F; Marino, R A; Mast, D; Mendez-Abreu, J; Peletier, R F P; Sánchez-Blázquez, P; Sánchez, S F; Trager, S C; Bosch, R C E van den; Vazdekis, A; Walcher, C J; Zhu, L; Zibetti, S; Ziegler, B; Bland-Hawthorn, J

    2016-01-01

    In this letter we describe how we use stellar dynamics information to constrain the shape of the stellar IMF in a sample of 27 early-type galaxies from the CALIFA survey. We obtain dynamical and stellar mass-to-light ratios, $\\Upsilon_\\mathrm{dyn}$ and $\\Upsilon_{\\ast}$, over a homogenous aperture of 0.5~$R_{e}$. We use the constraint $\\Upsilon_\\mathrm{dyn} \\ge \\Upsilon_{\\ast}$ to test two IMF shapes within the framework of the extended MILES stellar population models. We rule out a single power law IMF shape for 75% of the galaxies in our sample. Conversely, we find that a double power law IMF shape with a varying high-mass end slope is compatible (within 1$\\sigma$) with 95% of the galaxies. We also show that dynamical and stellar IMF mismatch factors give consistent results for the systematic variation of the IMF in these galaxies.

  2. Border Collision Bifurcations in a Generalized Model of Population Dynamics

    Directory of Open Access Journals (Sweden)

    Lilia M. Ladino

    2016-01-01

    Full Text Available We analyze the dynamics of a generalized discrete time population model of a two-stage species with recruitment and capture. This generalization, which is inspired by other approaches and real data that one can find in literature, consists in considering no restriction for the value of the two key parameters appearing in the model, that is, the natural death rate and the mortality rate due to fishing activity. In the more general case the feasibility of the system has been preserved by posing opportune formulas for the piecewise map defining the model. The resulting two-dimensional nonlinear map is not smooth, though continuous, as its definition changes as any border is crossed in the phase plane. Hence, techniques from the mathematical theory of piecewise smooth dynamical systems must be applied to show that, due to the existence of borders, abrupt changes in the dynamic behavior of population sizes and multistability emerge. The main novelty of the present contribution with respect to the previous ones is that, while using real data, richer dynamics are produced, such as fluctuations and multistability. Such new evidences are of great interest in biology since new strategies to preserve the survival of the species can be suggested.

  3. Zentralamerikas Jugendbanden: "Maras" in Honduras, El Salvador und Guatemala

    OpenAIRE

    Peetz, Peter

    2004-01-01

    "In El Salvador hat das Parlament Ende letzten Jahres ein neues Gesetz verabschiedet, nach dem die Mitgliedschaft in einer mara (Jugendbande, Streetgang) mit zwei bis fünf Jahren Gefängnis bestraft wird. Dem oder der Beschuldigten muss keine konkrete Straftat nachgewiesen werden. Einige Monate zuvor hatte der honduranische Kongress einstimmig eine ähnliche Regelung beschlossen. Mitte Januar 2004 unterzeichneten die Präsidenten von Guatemala, El Salvador, Honduras und Nikaragua ein Abkommen, i...

  4. State Approaches Toward Reducing Youth Violence in Honduras and Nicaragua

    Science.gov (United States)

    2015-09-01

    Study on Homicide 2013, 126. 44 Instituto Nacional de Estadística (INE), Cuadragésima Primera Encuesta Permanente de Hogares: Resumen Ejecutivo, Vol. 41...See Table 1).47 45 INE, Cuadragésima Primera Encuesta Permanente de Hogares, 6,14. 46 Sonja Wolf...Cuadragésima Primera Encuesta Permanente de Hogares: Resumen Ejecutivo. Vol. 41 Tegucigalpa, Honduras: INE, 2011. Jütersonke, Oliver, Robert Muggah, and

  5. Death in the Afternoon: Honduras, Hemingway, and Duncan Strong

    Directory of Open Access Journals (Sweden)

    Thomas W. Cuddy

    2002-11-01

    Full Text Available Archaeologist William Duncan Strong and author Ernest Hemingway are both known for the exemplary works they produced in their respective fields. Most people don't know the shared similarities in the parallel lives of these two men, and the greater social forces that shaped them. This essay takes a Hemingway-like approach to the life of Duncan Strong, using excerpts from Strong's expedition to Honduras in 1933 to draw analogy with the publicly renowned life of Ernest Hemingway.

  6. Sustainable energy policy in Honduras: Diagnosis and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Wilfredo C. [National Directorate of Energy, Tegucigalpa (MDC) (Honduras); Universidad Nacional Autonoma de Honduras, Facultad de Ciencias, Escuela de Fisica, Tegucigalpa (MDC) (Honduras); Ojeda, Osvaldo A. [Universidad Nacional de la Patagonia San Juan Bosco (Argentina); Flores, Marco A.; Rivas, Francisco R. [Universidad Nacional Autonoma de Honduras, Facultad de Ciencias, Escuela de Fisica, Tegucigalpa (MDC) (Honduras)

    2011-02-15

    In view of having a still unexploited potential of natural resources available for clean energy and the possibility of using the regional electricity market in Central America, Honduras has several potential energy sources. The growing dependence on oil and the imminent increase in international prices of fossil fuels, coupled with the necessity of changing the energy sector arrangement, the State of Honduras has taken the lead for the development of a long-term sustainable energy policy. This energy policy must be able to develop various energy sources and guide both, the government and the private sector, to the planning and development of alternative energy sources and sustainable growth of the Honduran economy. In this paper, the various energy diagnoses and the potential for changing the Honduran energy mix are presented, as well as the investment required for sustainable management of the energy sector. Furthermore, the objectives of the energy policy and plan up to the year 2030 are presented, outlining the investment possibilities for the energy sector development, showing their costs and timeframes. - Research Highlights: {yields} This paper shows the development of a long-term energy policy for Honduras. {yields} The various diagnoses of the energy sector in Honduras are shown, considering the use of wood, biomass, biofuels, electricity, transportation, hydrocarbons and rural electrification. {yields} The most relevant results of the analysis of energy forecasting are shown, for which the LEAP software was used. {yields} The objectives of the energy policy and plan up to the year 2030 are presented, outlining the investment possibilities for the energy sector development, showing their costs and timeframes.

  7. Drug consumption by medical students in tegucigalpa, Honduras

    OpenAIRE

    Juana Carolina Buchanan; Sandra Cristina Pillon

    2008-01-01

    The use of drugs, in Honduras, involves 25% of college students. The most used substances include legal and recreational drugs, such as alcohol. This study aimed to identify the use of drugs and socio-demographic factors in a sample of 260 medical students. RESULTS: Average age of 20 years old, unemployed and religious women, single, with no children. Alcohol was the most consumed drug in the last six months for recreational purposes. The following stimulants were frequently consumed: caffein...

  8. Drivers of waterfowl population dynamics: from teal to swans

    Science.gov (United States)

    Koons, David N.; Gunnarsson, Gunnar; Schmutz, Joel A.; Rotella, Jay J.

    2014-01-01

    Waterfowl are among the best studied and most extensively monitored species in the world. Given their global importance for sport and subsistence hunting, viewing and ecosystem functioning, great effort has been devoted since the middle part of the 20th century to understanding both the environmental and demographic mechanisms that influence waterfowl population and community dynamics. Here we use comparative approaches to summarise and contrast our understanding ofwaterfowl population dynamics across species as short-lived as the teal Anas discors and A.crecca to those such as the swans Cygnus sp. which have long life-spans. Specifically, we focus on population responses to vital rate perturbations across life history strategies, discuss bottom-up and top-down responses of waterfowlpopulations to global change, and summarise our current understanding of density dependence across waterfowl species. We close by identifying research needs and highlight ways to overcome the challenges of sustainably managing waterfowl populations in the 21st century.

  9. Connection between dynamically derived IMF normalisation and stellar population parameters

    CERN Document Server

    McDermid, Richard M; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Bureau, Martin; Crocker, Alison F; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M

    2014-01-01

    We report on empirical trends between the dynamically determined stellar initial mass function (IMF) and stellar population properties for a complete, volume-limited sample of 260 early-type galaxies from the Atlas3D project. We study trends between our dynamically-derived IMF normalisation and absorption line strengths, and interpret these via single stellar population- (SSP-) equivalent ages, abundance ratios (measured as [alpha/Fe]), and total metallicity, [Z/H]. We find that old and alpha-enhanced galaxies tend to have on average heavier (Salpeter-like) mass normalisation of the IMF, but stellar population does not appear to be a good predictor of the IMF, with a large range of normalisation at a given population parameter. As a result, we find weak IMF-[alpha/Fe] and IMF-age correlations, and no significant IMF-[Z/H] correlation. The observed trends appear significantly weaker than those reported in studies that measure the IMF normalisation via low-mass star demographics inferred through stellar spectra...

  10. Physiologically structured populations with diffusion and dynamic boundary conditions.

    Science.gov (United States)

    Farkas, József Z; Hinow, Peter

    2011-04-01

    We consider a linear size-structured population model with diffusion in the size-space. Individuals are recruited into the population at arbitrary sizes. We equip the model with generalized Wentzell-Robin (or dynamic) boundary conditions. This approach allows the modelling of populations in which individuals may have distinguished physiological states. We establish existence and positivity of solutions by showing that solutions are governed by a positive quasicontractive semigroup of linear operators on the biologically relevant state space. These results are obtained by establishing dissipativity of a suitably perturbed semigroup generator. We also show that solutions of the model exhibit balanced exponential growth, that is, our model admits a finite-dimensional global attractor. In case of strictly positive fertility we are able to establish that solutions in fact exhibit asynchronous exponential growth.

  11. Pattern formation and coexistence domains for a nonlocal population dynamics

    CERN Document Server

    da Cunha, J A R; Oliveira, F A

    2011-01-01

    In this communication we propose a most general equation to study pattern formation for one-species population and their limit domains in systems of length L. To accomplish this we include non-locality in the growth and competition terms where the integral kernels are now depend on characteristic length parameters alpha and beta. Therefore, we derived a parameter space (alpha,beta) where it is possible to analyze a coexistence curve alpha*=alpha*(\\beta) which delimits domains for the existence (or not) of pattern formation in population dynamics systems. We show that this curve has an analogy with coexistence curve in classical thermodynamics and critical phenomena physics. We have successfully compared this model with experimental data for diffusion of Escherichia coli populations.

  12. Linking animal population dynamics to alterations in foraging behaviour

    DEFF Research Database (Denmark)

    Nabe-Nielsen, Jacob; Sibly, Richard; Tougaard, Jakob

    Background/Question/Methods The survival of animal populations is strongly influenced by the individuals’ ability to forage efficiently, yet there are few studies of how populations respond when disturbances cause animals to deviate from their natural foraging behavior. Animals that respond...... was not jeopardized even when disturbances were simulated to have a relatively large and persistent effect on the behavior of individual animals. Porpoises were simulated to move away from noisy objects, preventing them from returning to the known food patches in that area. This resulted in decreasing energy reserves...... that are increasingly exposed to noise from ships, wind turbines, etc. In the present study we investigate how the dynamics of the harbor porpoise population (Phocoena phocoena) in the inner Danish waters is influenced by disturbances using an agent- based simulation model. In the model animal movement, and hence...

  13. Connection between dynamically derived IMF normalisation and stellar populations

    CERN Document Server

    McDermid, Richard M

    2015-01-01

    In this contributed talk I present recent results on the connection between stellar population properties and the normalisation of the stellar initial mass function (IMF) measured using stellar dynamics, based on a large sample of 260 early-type galaxies observed as part of the Atlas3D project. This measure of the IMF normalisation is found to vary non-uniformly with age- and metallicity-sensitive absorption line strengths. Applying single stellar population models, there are weak but measurable trends of the IMF with age and abundance ratio. Accounting for the dependence of stellar population parameters on velocity dispersion effectively removes these trends, but subsequently introduces a trend with metallicity, such that `heavy' IMFs favour lower metallicities. The correlations are weaker than those found from previous studies directly detecting low-mass stars, suggesting some degree of tension between the different approaches of measuring the IMF. Resolving these discrepancies will be the focus of future w...

  14. Exploration geothermal gradient drilling, Platanares, Honduras, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.J.; Laughlin, A.W.; Ruefenacht, H.D.; Goff, F.E.; Heiken, G.; Ramos, N.

    1988-01-01

    This paper is a review and summary of the core drilling operations component of the Honduras Geothermal Resource Development Project at the Platanares geothermal prospect in Honduras, Central America. Three intermediate depth (428 to 679 m) coreholes are the first continuously cored geothermal exploration boreholes in Honduras. These coring operations are part of the Central America Energy Resource Project (CAERP) effort funded by the Agency for International Development (AID) and implemented by the Los Alamos National Laboratory (Los Alamos) in cooperation with the Empresa Nacional de Energia Electrica (ENEE) and the United States Geological Survey (USGS). This report emphasizes coring operations with reference to the stratigraphy, thermal gradient, and flow test data of the boreholes. The primary objectives of this coring effort were (1) to obtain quantitative information on the temperature distribution as a function of depth, (2) to recover fluids associated with the geothermal reservoir, (3) to recover 75% or better core from the subsurface rock units, and (4) to drill into the subsurface rock as deeply as possible in order to get information on potential reservoir rocks, fracture density, permeabilities, and alteration histories of the rock units beneath the site. The three exploration coreholes drilled to depths of 650, 428 and 679 m, respectively, encountered several hot water entries. Coring operations and associated testing began in mid-October 1986 and were completed at the end of June 1987.

  15. Challenges for traditional birth attendants in northern rural Honduras.

    Science.gov (United States)

    Low, Lisa Kane; Scheib, Holly; Bailey, Joanne Motino; Sacks, Emma

    2006-03-01

    to explore the relationship between community-based parteras, the staff at the Centro Materno Infantil (Mother-Child Centre), and other public health facilities within the district of Morazán in northern rural Honduras during the transition to new models of maternity care. focus-group discussions with two groups composed of a convenience sample of community parteras. After verbatim translation of the interviews, the transcripts were analysed for content. the Centro de Salud of Morazán, Yoro Honduras. 28 community-based parteras and one partero (male community midwife). five themes emerged from the focus group data: the shared view that attending birth is connected to a religious calling; the desire for additional training; the desire for support from, and connection to, existing public-health services and infrastructure; the role of parteras in providing services to women who otherwise would not receive care; and the lack of new parteras to carry on this work in the future. traditional birth attendants are still relied upon to serve more than half of the childbearing women in Honduras. The findings from the focus groups provide a foundation upon which to strengthen the relationship between community-based parteras and the government-funded systems of health care during this time of transition to new models of maternity care.

  16. Environmental influence on population dynamics of the bivalve Anomalocardia brasiliana

    Science.gov (United States)

    Corte, Guilherme Nascimento; Coleman, Ross A.; Amaral, A. Cecília Z.

    2017-03-01

    Understanding how species respond to the environment in terms of population attributes (e.g. abundance, growth, mortality, fecundity, and productivity) is essential to protect ecologically and economically important species. Nevertheless, responses of macrobenthic populations to environmental features are overlooked due to the need of consecutive samplings and time-consuming measurements. We examined the population dynamics of the filter-feeding bivalve Anomalocardia brasiliana on a tidal flat over the course of one year to investigate the hypothesis that, as accepted for macrobenthic communities, populations inhabiting environments with low hydrodynamic conditions such as tidal flat should have higher attributes than populations inhabiting more energetic habitats (i.e. areas more influenced by wave energy such as reflective and intermediate beaches). This would be expected because the harsh conditions of more energetic habitats force organisms to divert more energy towards maintenance, resulting in lower population attributes. We found that A. brasiliana showed moderate growth and secondary production at the study area. Moreover the recruitment period was restricted to a few months. A comparison with previous studies showed that, contrary to expected, A. brasiliana populations from areas with low hydrodynamic conditions have lower abundance, growth, recruitment and turnover rate. It is likely that morphodynamic characteristics recorded in these environments, such as larger periods of air exposure and lower water circulation, may affect food conditions for filter-feeding species and increase competition. In addition, these characteristics may negatively affect macrobenthic species by enhancing eutrophication processes and anoxia. Overall, our results suggest that models accepted and applied at the macrobenthic community level might not be directly extended to A. brasiliana populations.

  17. Disasters and development in agricultural input markets: bean seed markets in Honduras after Hurricane Mitch.

    Science.gov (United States)

    Mainville, Denise Y

    2003-06-01

    The bulk of developing countries' populations and poor depend on agriculture for food and income. While rural economies and people are generally the most severely affected by natural disasters, little is known about how disasters and subsequent relief activities affect agricultural markets with differing levels of development. The article addresses this gap, drawing evidence from bean seed markets in Honduras after Hurricane Mitch. Case studies are used to address hypotheses about a disaster's effects on supply and demand in seed markets, farmers' responses and the performance of relief interventions in markets showing differing levels of development. The results show the importance of tailoring relief interventions to the markets that they will affect and to the specific effects of a disaster; the potential to use local and emerging seed distribution channels in a relief intervention; and opportunities for relief activities to strengthen community seed systems.

  18. Population Dynamics of Early Human Migration in Britain

    Science.gov (United States)

    Vahia, Mayank N.; Ladiwala, Uma; Mahathe, Pavan; Mathur, Deepak

    2016-01-01

    Background Early human migration is largely determined by geography and human needs. These are both deterministic parameters when small populations move into unoccupied areas where conflicts and large group dynamics are not important. The early period of human migration into the British Isles provides such a laboratory which, because of its relative geographical isolation, may allow some insights into the complex dynamics of early human migration and interaction. Method and Results We developed a simulation code based on human affinity to habitable land, as defined by availability of water sources, altitude, and flatness of land, in choosing the path of migration. Movement of people on the British island over the prehistoric period from their initial entry points was simulated on the basis of data from the megalithic period. Topographical and hydro-shed data from satellite databases was used to define habitability, based on distance from water bodies, flatness of the terrain, and altitude above sea level. We simulated population movement based on assumptions of affinity for more habitable places, with the rate of movement tempered by existing populations. We compared results of our computer simulations with genetic data and show that our simulation can predict fairly accurately the points of contacts between different migratory paths. Such comparison also provides more detailed information about the path of peoples’ movement over ~2000 years before the present era. Conclusions We demonstrate an accurate method to simulate prehistoric movements of people based upon current topographical satellite data. Our findings are validated by recently-available genetic data. Our method may prove useful in determining early human population dynamics even when no genetic information is available. PMID:27148959

  19. Population Dynamics of Early Human Migration in Britain.

    Directory of Open Access Journals (Sweden)

    Mayank N Vahia

    Full Text Available Early human migration is largely determined by geography and human needs. These are both deterministic parameters when small populations move into unoccupied areas where conflicts and large group dynamics are not important. The early period of human migration into the British Isles provides such a laboratory which, because of its relative geographical isolation, may allow some insights into the complex dynamics of early human migration and interaction.We developed a simulation code based on human affinity to habitable land, as defined by availability of water sources, altitude, and flatness of land, in choosing the path of migration. Movement of people on the British island over the prehistoric period from their initial entry points was simulated on the basis of data from the megalithic period. Topographical and hydro-shed data from satellite databases was used to define habitability, based on distance from water bodies, flatness of the terrain, and altitude above sea level. We simulated population movement based on assumptions of affinity for more habitable places, with the rate of movement tempered by existing populations. We compared results of our computer simulations with genetic data and show that our simulation can predict fairly accurately the points of contacts between different migratory paths. Such comparison also provides more detailed information about the path of peoples' movement over ~2000 years before the present era.We demonstrate an accurate method to simulate prehistoric movements of people based upon current topographical satellite data. Our findings are validated by recently-available genetic data. Our method may prove useful in determining early human population dynamics even when no genetic information is available.

  20. The Armed Forces and the Fight against Drug-Trafficking in Honduras (Las FUERZAS ARMADAS EN EL COMBATE AL NARCOTR FICO EN HONDURAS)

    Science.gov (United States)

    2013-06-13

    Narcotráfico y el Crimen Organizado y Maras de Honduras. PNUD (Tegucigalpa, Honduras, 15 de diciembre del 2004), 10. 3Ibid. 2...delincuencia común, el crimen organizado , el lavado de activos, la trata de personas y el tráfico de armas, ya que todos estos actos delictivos están ligados...naturaleza transnacional y una de las manifestaciones más sofisticadas del crimen organizado , comenzó a tener notoriedad en Honduras en la década de

  1. Stationary Stability for Evolutionary Dynamics in Finite Populations

    Directory of Open Access Journals (Sweden)

    Marc Harper

    2016-08-01

    Full Text Available We demonstrate a vast expansion of the theory of evolutionary stability to finite populations with mutation, connecting the theory of the stationary distribution of the Moran process with the Lyapunov theory of evolutionary stability. We define the notion of stationary stability for the Moran process with mutation and generalizations, as well as a generalized notion of evolutionary stability that includes mutation called an incentive stable state (ISS candidate. For sufficiently large populations, extrema of the stationary distribution are ISS candidates and we give a family of Lyapunov quantities that are locally minimized at the stationary extrema and at ISS candidates. In various examples, including for the Moran and Wright–Fisher processes, we show that the local maxima of the stationary distribution capture the traditionally-defined evolutionarily stable states. The classical stability theory of the replicator dynamic is recovered in the large population limit. Finally we include descriptions of possible extensions to populations of variable size and populations evolving on graphs.

  2. Dynamic distributions and population declines of Golden-winged Warblers

    Science.gov (United States)

    Rosenberg, Kenneth V.; Will, Tom; Buehler, David A.; Barker Swarthout, Sara; Thogmartin, Wayne E.; Chandler, Richard

    2016-01-01

    With an estimated breeding population in 2010 of 383,000 pairs, the Golden-winged Warbler (Vermivora chrysoptera) is among the most vulnerable and steeply declining of North American passerines. This species also has exhibited among the most dynamic breeding distributions, with populations expanding and then contracting over the past 150 years in response to regional habitat changes, interactions with closely related Blue-winged Warblers (V. cyanoptera), and possibly climate change. Since 1966, the rangewide population has declined by >70% (-2.3% per year; latest North American Breeding Bird Survey data), with much steeper declines in the Appalachian Mountains bird conservation region (-8.3% per year, 98% overall decline). Despite apparently stable or increasing populations in the northwestern part of the range (Minnesota, Manitoba), population estimates for Golden-winged Warbler have continued to decline by 18% from the decade of the 1990s to the 2000s. Population modeling predicts a further decline to roughly 37,000 individuals by 2100, with the species likely to persist only in Manitoba, Minnesota, and possibly Ontario. To delineate the present-day distribution and to identify population concentrations that could serve as conservation focus areas, we compiled rangewide survey data collected in 2000-2006 in 21 states and 3 Canadian provinces, as part of the Golden-winged Warbler Atlas Project (GOWAP), supplemented by state and provincial Breeding Bird Atlas data and more recent observations in eBird. Based on >8,000 GOWAP surveys for Golden-winged and Blue-winged warblers and their hybrids, we mapped occurrence of phenotypically pure and mixed populations in a roughly 0.5-degree grid across the species’ ranges. Hybrids and mixed Golden-winged-Blue-winged populations occurred in a relatively narrow zone across Minnesota, Wisconsin, Michigan, southern Ontario, and northern New York. Phenotypically pure Golden-winged Warbler populations occurred north of this

  3. Alternating event processes during lifetimes: population dynamics and statistical inference.

    Science.gov (United States)

    Shinohara, Russell T; Sun, Yifei; Wang, Mei-Cheng

    2017-08-07

    In the literature studying recurrent event data, a large amount of work has been focused on univariate recurrent event processes where the occurrence of each event is treated as a single point in time. There are many applications, however, in which univariate recurrent events are insufficient to characterize the feature of the process because patients experience nontrivial durations associated with each event. This results in an alternating event process where the disease status of a patient alternates between exacerbations and remissions. In this paper, we consider the dynamics of a chronic disease and its associated exacerbation-remission process over two time scales: calendar time and time-since-onset. In particular, over calendar time, we explore population dynamics and the relationship between incidence, prevalence and duration for such alternating event processes. We provide nonparametric estimation techniques for characteristic quantities of the process. In some settings, exacerbation processes are observed from an onset time until death; to account for the relationship between the survival and alternating event processes, nonparametric approaches are developed for estimating exacerbation process over lifetime. By understanding the population dynamics and within-process structure, the paper provide a new and general way to study alternating event processes.

  4. Population Dynamics of the Giant Clam, Tridacna maxima, at Rose Atoll

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — There is a paucity of knowledge on the population dynamics of the giant clams of the family Tridacnidae. Such information on population dynamics is necessary for...

  5. Honduras: una mezcla de cambio y continuidad Honduras: A Mix of Change and Continuity

    Directory of Open Access Journals (Sweden)

    MICHELLE M TAYLOR-ROBINSON

    2009-01-01

    Full Text Available Este artículo analiza las fuentes de cambio y de continuidad en la política de Honduras para entender si el régimen democrático esta progresando hacia la consolidación. El presente artículo brevemente expone los eventos más relevantes del periodo 2008. Estos incluyen las relaciones entre el Presidente Zelaya y Hugo Chávez, los esfuerzos de las mujeres y de los afrohondureños para aumentar su representación política y las elecciones primarias de los partidos tradicionales. Varios cambios indican que la democracia está más fuerte -la expansión de la representación política parece continuará y existe la posibilidad de que el Congreso funcione como un freno contra el presidente- pero estos cambios todavía no están consolidados.This article analyzes the sources of change and of continuity in Honduran politics to better understand if the democratic regime is progressing toward consolidation. The article briefly presents the most relevant events of 2008, including relations between President Zelaya and Hugo Chavez, the efforts of women and Afro-Hondurans to increase their representation, and the primary elections of the traditional parties. Various changes indicate that democracy is stronger -that expansion of representation appears to be continuing, the possibility that the congress may function as a break on the president- but these changes still are not consolidated.

  6. Chlamydia trachomatis and genital human papillomavirus infections in female university students in Honduras.

    NARCIS (Netherlands)

    Tabora, N.; Zelaya, A.; Bakkers, J.; Melchers, W.J.; Ferrera, A.

    2005-01-01

    Sexually transmitted infections are a serious health problem in Honduras. Human papillomavirus (HPV) and Chlamydia trachomatis are major causes of sexually transmitted diseases. To determine the prevalence of C. trachomatis and HPV in young women, 100 female university students in Honduras were assa

  7. Educational Facility Evaluations of Primary Schools in Rural Honduras: Departments of Cortes and Meambar.

    Science.gov (United States)

    Council of Educational Facility Planners, International, Scottsdale, AZ.

    A team of 11 educational facility planners and architects from the United States and Canada conducted a facility evaluation of schools in the rural areas of Meambar and Cortes, Honduras. Team members were all part of the Council of Educational Facility Planners, International and traveled to Honduras under the auspices of a Christian mission…

  8. Chlamydia trachomatis and genital human papillomavirus infections in female university students in Honduras.

    NARCIS (Netherlands)

    Tabora, N.; Zelaya, A.; Bakkers, J.; Melchers, W.J.; Ferrera, A.

    2005-01-01

    Sexually transmitted infections are a serious health problem in Honduras. Human papillomavirus (HPV) and Chlamydia trachomatis are major causes of sexually transmitted diseases. To determine the prevalence of C. trachomatis and HPV in young women, 100 female university students in Honduras were assa

  9. EU Support for Justice and Security Sector Reform in Honduras and Guatemala

    NARCIS (Netherlands)

    van der Borgh, G.J.C.

    2016-01-01

    This desk study reviews the literature on EU programmes that supported security and justice reform in Guatemala and Honduras, focusing on two programs: the programme in support of the security sector (PASS) in Honduras and the International Commission against Impunity in Guatemala (CICIG). The

  10. Analisis de las Condiciones de Salud del Nino de 0-6 anos en Honduras.

    Science.gov (United States)

    Matamoros, Douglas Alberto

    1987-01-01

    Examines the National Pediatric Service and the research program of the Maternity-Infant-Hospital-School in Honduras. Reports that health conditions of young children (birth to six years) in Honduras are appalling and that available funds for health services are inadequate, reflecting the country's economic and social crisis. (NH)

  11. A comparative analysis of locally based conservation education programs that promote issue awareness and community solutions within Honduras and the United States

    Science.gov (United States)

    Weber, Nicole R.

    Public understanding and concern for environment issues is critical to conservation efforts. In this study, I investigated education programs focused on the local environmental issues and their impact on sense of place, environmental knowledge, empowerment and awareness (Honduras and Boston). I hypothesized that the curriculum will have an effect on multiple student measures and teachers who participate in workshops will have greater ownership of the curriculum, influencing curriculum's effectiveness. Then I looked at the relation of environmental knowledge to environmental connection, at the regional (Honduras) and international levels (Honduras vs. United States), comparing cultural differences in same measures mentioned. I hypothesized that a population connected to their natural surroundings will have an embedded biological understanding and appreciation of their surroundings. I surveyed a total of 887 students (727 Honduras, 160 Boston) and 293 teachers (Honduras), with participant and nonparticipant teachers included, in a pre/post/follow-up survey design. To evaluate these hypotheses, I used multiple measures to assess program success and regional differences: implicit measures (general sense of place); explicit measures (knowledge of problems and solutions; degree of specificity in thinking about these issues); and affective and attitudinal components (sense of empowerment). For the exploratory study, I gathered parallel data from teachers, so that the effects of the program on both teachers and students would be evident. Our results indicate that there were significant changes in number of problem and solution types proposed by students, that students' responses matched those of their teacher on some measures (but not all) by the end of the program. In Honduras, the main effect of being in the teacher workshop appears to be in their willingness to teach environmental education. Results for student's sense of place and environmental empowerment were

  12. Population dynamics of minimally cognitive individuals. Part I: Introducing knowledge into the dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Schmieder, R.W.

    1995-07-01

    The author presents a new approach for modeling the dynamics of collections of objects with internal structure. Based on the fact that the behavior of an individual in a population is modified by its knowledge of other individuals, a procedure for accounting for knowledge in a population of interacting objects is presented. It is assumed that each object has partial (or complete) knowledge of some (or all) other objects in the population. The dynamical equations for the objects are then modified to include the effects of this pairwise knowledge. This procedure has the effect of projecting out what the population will do from the much larger space of what it could do, i.e., filtering or smoothing the dynamics by replacing the complex detailed physical model with an effective model that produces the behavior of interest. The procedure therefore provides a minimalist approach for obtaining emergent collective behavior. The use of knowledge as a dynamical quantity, and its relationship to statistical mechanics, thermodynamics, information theory, and cognition microstructure are discussed.

  13. Particle tagging and its implications for stellar population dynamics

    Science.gov (United States)

    Le Bret, Theo; Pontzen, Andrew; Cooper, Andrew P.; Frenk, Carlos; Zolotov, Adi; Brooks, Alyson M.; Governato, Fabio; Parry, Owen H.

    2017-07-01

    We establish a controlled comparison between the properties of galactic stellar haloes obtained with hydrodynamical simulations and with 'particle tagging'. Tagging is a fast way to obtain stellar population dynamics: instead of tracking gas and star formation, it 'paints' stars directly on to a suitably defined subset of dark matter particles in a collisionless, dark-matter-only simulation. Our study shows that 'live' particle tagging schemes, where stellar masses are painted on to the dark matter particles dynamically throughout the simulation, can generate good fits to the hydrodynamical stellar density profiles of a central Milky Way-like galaxy and its most prominent substructure. Energy diffusion processes are crucial to reshaping the distribution of stars in infalling spheroidal systems and hence the final stellar halo. We conclude that the success of any particular tagging scheme hinges on this diffusion being taken into account, and discuss the role of different subgrid feedback prescriptions in driving this diffusion.

  14. Population Dynamics of Patients with Bacterial Resistance in Hospital Environment

    Directory of Open Access Journals (Sweden)

    Leilei Qu

    2016-01-01

    Full Text Available During the past decades, the increase of antibiotic resistance has become a major concern worldwide. The researchers found that superbugs with new type of resistance genes (NDM-1 have two aspects of transmission characteristics; the first is that the antibiotic resistance genes can horizontally transfer among bacteria, and the other is that the superbugs can spread between humans through direct contact. Based on these two transmission mechanisms, we study the dynamics of population in hospital environment where superbugs exist. In this paper, we build three mathematic models to illustrate the dynamics of patients with bacterial resistance in hospital environment. The models are analyzed using stability theory of differential equations. Positive equilibrium points of the system are investigated and their stability analysis is carried out. Moreover, the numerical simulation of the proposed model is also performed which supports the theoretical findings.

  15. Mosquito population dynamics from cellular automata-based simulation

    Science.gov (United States)

    Syafarina, Inna; Sadikin, Rifki; Nuraini, Nuning

    2016-02-01

    In this paper we present an innovative model for simulating mosquito-vector population dynamics. The simulation consist of two stages: demography and dispersal dynamics. For demography simulation, we follow the existing model for modeling a mosquito life cycles. Moreover, we use cellular automata-based model for simulating dispersal of the vector. In simulation, each individual vector is able to move to other grid based on a random walk. Our model is also capable to represent immunity factor for each grid. We simulate the model to evaluate its correctness. Based on the simulations, we can conclude that our model is correct. However, our model need to be improved to find a realistic parameters to match real data.

  16. Knowledge epidemics and population dynamics models for describing idea diffusion

    CERN Document Server

    Vitanov, Nikolay K

    2012-01-01

    The diffusion of ideas is often closely connected to the creation and diffusion of knowledge and to the technological evolution of society. Because of this, knowledge creation, exchange and its subsequent transformation into innovations for improved welfare and economic growth is briefly described from a historical point of view. Next, three approaches are discussed for modeling the diffusion of ideas in the areas of science and technology, through (i) deterministic, (ii) stochastic, and (iii) statistical approaches. These are illustrated through their corresponding population dynamics and epidemic models relative to the spreading of ideas, knowledge and innovations. The deterministic dynamical models are considered to be appropriate for analyzing the evolution of large and small societal, scientific and technological systems when the influence of fluctuations is insignificant. Stochastic models are appropriate when the system of interest is small but when the fluctuations become significant for its evolution...

  17. Plasmodium vivax Population Structure and Transmission Dynamics in Sabah Malaysia

    Science.gov (United States)

    Abdullah, Noor Rain; Barber, Bridget E.; William, Timothy; Norahmad, Nor Azrina; Satsu, Umi Rubiah; Muniandy, Prem Kumar; Ismail, Zakiah; Grigg, Matthew J.; Jelip, Jenarun; Piera, Kim; von Seidlein, Lorenz; Yeo, Tsin W.; Anstey, Nicholas M.; Price, Ric N.; Auburn, Sarah

    2013-01-01

    Despite significant progress in the control of malaria in Malaysia, the complex transmission dynamics of P. vivax continue to challenge national efforts to achieve elimination. To assess the impact of ongoing interventions on P. vivax transmission dynamics in Sabah, we genotyped 9 short tandem repeat markers in a total of 97 isolates (8 recurrences) from across Sabah, with a focus on two districts, Kota Marudu (KM, n = 24) and Kota Kinabalu (KK, n = 21), over a 2 year period. STRUCTURE analysis on the Sabah-wide dataset demonstrated multiple sub-populations. Significant differentiation (FST  = 0.243) was observed between KM and KK, located just 130 Km apart. Consistent with low endemic transmission, infection complexity was modest in both KM (mean MOI  = 1.38) and KK (mean MOI  = 1.19). However, population diversity remained moderate (HE  = 0.583 in KM and HE  = 0.667 in KK). Temporal trends revealed clonal expansions reflecting epidemic transmission dynamics. The haplotypes of these isolates declined in frequency over time, but persisted at low frequency throughout the study duration. A diverse array of low frequency isolates were detected in both KM and KK, some likely reflecting remnants of previous expansions. In accordance with clonal expansions, high levels of Linkage Disequilibrium (IAS >0.5 [Pdiversity. In summary, Sabah's shrinking P. vivax population appears to have rendered this low endemic setting vulnerable to epidemic expansions. Migration may play an important role in the introduction of new parasite strains leading to epidemic expansions, with important implications for malaria elimination. PMID:24358203

  18. Applications of Perron-Frobenius theory to population dynamics.

    Science.gov (United States)

    Li, Chi-Kwong; Schneider, Hans

    2002-05-01

    By the use of Perron-Frobenius theory, simple proofs are given of the Fundamental Theorem of Demography and of a theorem of Cushing and Yicang on the net reproductive rate occurring in matrix models of population dynamics. The latter result, which is closely related to the Stein-Rosenberg theorem in numerical linear algebra, is further refined with some additional nonnegative matrix theory. When the fertility matrix is scaled by the net reproductive rate, the growth rate of the model is $1$. More generally, we show how to achieve a given growth rate for the model by scaling the fertility matrix. Demographic interpretations of the results are given.

  19. Mechanical reaction-diffusion model for bacterial population dynamics

    CERN Document Server

    Ngamsaad, Waipot

    2015-01-01

    The effect of mechanical interaction between cells on the spreading of bacterial population was investigated in one-dimensional space. A nonlinear reaction-diffusion equation has been formulated as a model for this dynamics. In this model, the bacterial cells are treated as the rod-like particles that interact, when contacting each other, through the hard-core repulsion. The repulsion introduces the exclusion process that causes the fast diffusion in bacterial population at high density. The propagation of the bacterial density as the traveling wave front in long time behavior has been analyzed. The analytical result reveals that the front speed is enhanced by the exclusion process---and its value depends on the packing fraction of cell. The numerical solutions of the model have been solved to confirm this prediction.

  20. pedagog: software for simulating eco-evolutionary population dynamics.

    Science.gov (United States)

    Coombs, Jason A; Letcher, B H; Nislow, K H

    2010-05-01

    pedagog is a Windows program that can be used to determine power for, and validate inferences drawn from, eco-evolutionary studies. It models dynamics of multiple populations and their interactions through individual-based simulations while simultaneously recording genotype, pedigree and trait information at the individual level. pedagog also allows for specification of heritable traits, natural and sexual selection acting upon those traits, population sampling schemes and incorporation of genetic and demographic errors into the output. Overall, parameters can be specified for genetic diversity, demographics, mating design, genetic and demographic errors, individual growth models, trait heritability and selection, and output formatting. Demographic parameters can be either age or function based, and all parameters can be drawn from 12 statistical distributions where appropriate. Simulation results can be automatically formatted for 57 existing software programs to facilitate postsimulation analyses. pedagog is freely available for download at https://bcrc.bio.umass.edu/pedigreesoftware/.

  1. Spatial and temporal dynamics of infected populations: the Mexican epidemic

    CERN Document Server

    Rodriguez-Meza, Mario A

    2012-01-01

    Recently the A/H1N1-2009 virus pandemic appeared in Mexico and in other nations. We present a study of this pandemic in the Mexican case using the SIR model to describe epidemics. This model is one of the simplest models but it has been a successful description of some epidemics of closed populations. We consider the data for the Mexican case and use the SIR model to make some predictions. Then, we generalize the SIR model in order to describe the spatial dynamics of the disease. We make a study of the spatial and temporal spread of the infected population with model parameters that are consistent with temporal SIR model parameters obtained by fitting to the Mexican case.

  2. State-dependent neutral delay equations from population dynamics.

    Science.gov (United States)

    Barbarossa, M V; Hadeler, K P; Kuttler, C

    2014-10-01

    A novel class of state-dependent delay equations is derived from the balance laws of age-structured population dynamics, assuming that birth rates and death rates, as functions of age, are piece-wise constant and that the length of the juvenile phase depends on the total adult population size. The resulting class of equations includes also neutral delay equations. All these equations are very different from the standard delay equations with state-dependent delay since the balance laws require non-linear correction factors. These equations can be written as systems for two variables consisting of an ordinary differential equation (ODE) and a generalized shift, a form suitable for numerical calculations. It is shown that the neutral equation (and the corresponding ODE--shift system) is a limiting case of a system of two standard delay equations.

  3. Population dynamics of minimally cognitive individuals. Part 2: Dynamics of time-dependent knowledge

    Energy Technology Data Exchange (ETDEWEB)

    Schmieder, R.W.

    1995-07-01

    The dynamical principle for a population of interacting individuals with mutual pairwise knowledge, presented by the author in a previous paper for the case of constant knowledge, is extended to include the possibility that the knowledge is time-dependent. Several mechanisms are presented by which the mutual knowledge, represented by a matrix K, can be altered, leading to dynamical equations for K(t). The author presents various examples of the transient and long time asymptotic behavior of K(t) for populations of relatively isolated individuals interacting infrequently in local binary collisions. Among the effects observed in the numerical experiments are knowledge diffusion, learning transients, and fluctuating equilibria. This approach will be most appropriate to small populations of complex individuals such as simple animals, robots, computer networks, agent-mediated traffic, simple ecosystems, and games. Evidence of metastable states and intermittent switching leads them to envision a spectroscopy associated with such transitions that is independent of the specific physical individuals and the population. Such spectra may serve as good lumped descriptors of the collective emergent behavior of large classes of populations in which mutual knowledge is an important part of the dynamics.

  4. Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations

    CERN Document Server

    Marks, Michael

    2011-01-01

    [abridged] The galactic field's late-type stellar single and binary population is calculated on the supposition that all stars form as binaries in embedded star clusters. A recently developed tool (Marks, Kroupa & Oh) is used to evolve the binary star distributions in star clusters for a few Myr so that a particular mixture of single and binary stars is achieved. On cluster dissolution the population enters the galactic field with these characteristics. The different contributions of single stars and binaries from individual star clusters which are selected from a power-law embedded star cluster mass function are then added up. This gives rise to integrated galactic field binary distribution functions (IGBDFs) resembling a galactic field's stellar content (Dynamical Population Synthesis). It is found that the binary proportion in the galactic field of a galaxy is larger the lower the minimum cluster mass, the lower the star formation rate, the steeper the embedded star cluster mass function and the larger...

  5. Population Dynamics in the Capitalist World-Economy

    Directory of Open Access Journals (Sweden)

    Daniela Danna

    2015-08-01

    Full Text Available World-systems analysis has given scant attention to population dynamics. Overlooked are large-scale macrohistorical population trends and their microhistorical foundation on procreative decisions-decisions which are taken by a historically changing subject of procreation: local elders or other authorities, head(s of the household, couples, and women. The discipline of demography is also not as helpful as it could be, given its basis in modernization theory, which fails to recognize intentionality in reproduction in pre-capitalist societies. It assumes a model of "demographic transition" from a state of "natural fertility" to a state of conscious family planning, while also treating mortality as independent of fertility Marxism recognized the importance of population as a source of labor for profit and capital accumulation. With its tools Sydney Coontz developed a demand for labor theory explaining in particular the decrease in the birth rate in England and the United States at the turn of the century This theory was f urther developed by anthropologists of the "mode of product ion and population pat terns " who, with other authors, offer useful theories and insights to advance world-historical research on population. This article explores connections between population dy namics and world-systems analysis. I explore six key questions at different levels of analysis, including: 1 Are there world-systems ' imperatives concerning human reproduction?; 2 Do human reproduction imperatives differ across world-systems.'?; 3 How do the (eventual systems requirements get transmitted to households and individuals'?; 4 Why do people have children.'?; 5 Who is the subject of procreation decisions'?; and 6 How is the number of offspring chosen? Finally, I offer guidelines for applying the six questions to the capitalist world-economy.

  6. Representation of dynamical stimuli in populations of threshold neurons.

    Directory of Open Access Journals (Sweden)

    Tatjana Tchumatchenko

    2011-10-01

    Full Text Available Many sensory or cognitive events are associated with dynamic current modulations in cortical neurons. This raises an urgent demand for tractable model approaches addressing the merits and limits of potential encoding strategies. Yet, current theoretical approaches addressing the response to mean- and variance-encoded stimuli rarely provide complete response functions for both modes of encoding in the presence of correlated noise. Here, we investigate the neuronal population response to dynamical modifications of the mean or variance of the synaptic bombardment using an alternative threshold model framework. In the variance and mean channel, we provide explicit expressions for the linear and non-linear frequency response functions in the presence of correlated noise and use them to derive population rate response to step-like stimuli. For mean-encoded signals, we find that the complete response function depends only on the temporal width of the input correlation function, but not on other functional specifics. Furthermore, we show that both mean- and variance-encoded signals can relay high-frequency inputs, and in both schemes step-like changes can be detected instantaneously. Finally, we obtain the pairwise spike correlation function and the spike triggered average from the linear mean-evoked response function. These results provide a maximally tractable limiting case that complements and extends previous results obtained in the integrate and fire framework.

  7. Impact of simian immunodeficiency virus infection on chimpanzee population dynamics.

    Directory of Open Access Journals (Sweden)

    Rebecca S Rudicell

    Full Text Available Like human immunodeficiency virus type 1 (HIV-1, simian immunodeficiency virus of chimpanzees (SIVcpz can cause CD4+ T cell loss and premature death. Here, we used molecular surveillance tools and mathematical modeling to estimate the impact of SIVcpz infection on chimpanzee population dynamics. Habituated (Mitumba and Kasekela and non-habituated (Kalande chimpanzees were studied in Gombe National Park, Tanzania. Ape population sizes were determined from demographic records (Mitumba and Kasekela or individual sightings and genotyping (Kalande, while SIVcpz prevalence rates were monitored using non-invasive methods. Between 2002-2009, the Mitumba and Kasekela communities experienced mean annual growth rates of 1.9% and 2.4%, respectively, while Kalande chimpanzees suffered a significant decline, with a mean growth rate of -6.5% to -7.4%, depending on population estimates. A rapid decline in Kalande was first noted in the 1990s and originally attributed to poaching and reduced food sources. However, between 2002-2009, we found a mean SIVcpz prevalence in Kalande of 46.1%, which was almost four times higher than the prevalence in Mitumba (12.7% and Kasekela (12.1%. To explore whether SIVcpz contributed to the Kalande decline, we used empirically determined SIVcpz transmission probabilities as well as chimpanzee mortality, mating and migration data to model the effect of viral pathogenicity on chimpanzee population growth. Deterministic calculations indicated that a prevalence of greater than 3.4% would result in negative growth and eventual population extinction, even using conservative mortality estimates. However, stochastic models revealed that in representative populations, SIVcpz, and not its host species, frequently went extinct. High SIVcpz transmission probability and excess mortality reduced population persistence, while intercommunity migration often rescued infected communities, even when immigrating females had a chance of being SIVcpz

  8. Hurricane Mitch: Landscape Analysis of Damaged Forest Resources of the Bay Islands and Caribbean Coast of Honduras

    Science.gov (United States)

    Doyle, Thomas W.; Michot, Thomas C.; Roetker, Fred; Sullivan, Jason; Melder, Marcus; Handley, Benjamin; Balmat, Jeff

    2002-01-01

    The advent of analog and digital video has provided amateur photographers with professional-like technology to capture dynamic images with ease and clarity. Videography is also rapidly changing traditional business and scientific applications. In the natural sciences, camcorders are being used largely to record timely observations of plant and animal behavior or consequence of some catastrophic event. Spectacular video of dynamic events such as hurricanes, volcanic eruptions and wildfire document the active process and aftermath. Scientists can analyze video images to quantify aspects of a given event, behavior, or response, temporally and spatially. In this study we demonstrate the simple use of an aerial application of videography to record the spatial extent and damage expression of mangrove forest in the Bay Islands and mainland coast of northern Honduras from wind damage following Hurricane Mitch (1998). In this study, we conducted a video overflight of coastal forests of the Bay Islands and mainland coast of northern Honduras 14 months after impact by Hurricane Mitch (1998). Coastal areas were identified where damage was evident and described relative to damage extent to forest cover, windfall orientation, and height of downed trees. The variability and spatial extent of impact on coastal forest resources is related to reconstructed wind profiles based on model simulations of Mitch's path, strength, and circulation during landfall.

  9. Comparative dynamics and life histories of coexisting dragonfly populations

    Energy Technology Data Exchange (ETDEWEB)

    Benke, A.C.; Benke, S.S.

    Several species of coexisting dragonfly larvae were studied for four consecutive years in a 1-ha old farm pond. Larval development, emergence patterns, and adult flight patterns showed that the most abundant species were univoltine and developed relatively synchronously (i.e., like a cohort). Three of the common species emerged in early spring, and the others emerged later in the summer. The common genera with the most similar microhabitat had a distinct temporal separation that may serve in reducing interspecific competition. However, coexisting congeneric species had almost identical life histories, supporting the hypothesis that ecological homologues can coexist because of ''errors of exploitation'' of the dominant species. The larval population dynamics of each dominant species (Ladona deplanata, Epitheca spp., and Celithemis fasciata) was characterized by a constant percentage numerical decline, coupled with with a dramatic biomass increase from time of hatching to final instar. Larval mortality during this period averaged 92 percent per annum, but population biomass increased at least tenfold during the same period for each species. Comparison of larval estimates with emergence data revealed that at least 80 percent of the final instars die just before leaving the water to emerge. Life history variations among species smoothed out composite density and biomass trends which averaged about 1,000 individuals/m/sup 2/ and 2 g dry wt/m/sup 2/, respectively. In general, population dynamics from year to year were quite consistent, indicating a relatively high degree of stability in terms of species composition and densities. (auth)

  10. La Cumbre Iberoamericana de Estoril: mucha Honduras pero poca profundidad

    OpenAIRE

    Malamud,Andrés

    2010-01-01

    Catorce países sobre 22 estuvieron representados por sus jefes de Estado y gobierno en la Cumbre Iberoamericana de Estoril. Los ocho restantes enviaron delegaciones de menor jerarquía, en algunos casos encabezadas por el canciller y en otros por funcionarios de segunda línea. Las reuniones de cúpula empezaron tarde y se extendieron mucho, debido sobre todo al desacuerdo respecto a la situación política en Honduras. La canciller en el exilio de Manuel Zelaya, Patricia Rodas, consiguió imponer ...

  11. Neural Population Dynamics Modeled by Mean-Field Graphs

    Science.gov (United States)

    Kozma, Robert; Puljic, Marko

    2011-09-01

    In this work we apply random graph theory approach to describe neural population dynamics. There are important advantages of using random graph theory approach in addition to ordinary and partial differential equations. The mathematical theory of large-scale random graphs provides an efficient tool to describe transitions between high- and low-dimensional spaces. Recent advances in studying neural correlates of higher cognition indicate the significance of sudden changes in space-time neurodynamics, which can be efficiently described as phase transitions in the neuropil medium. Phase transitions are rigorously defined mathematically on random graph sequences and they can be naturally generalized to a class of percolation processes called neuropercolation. In this work we employ mean-field graphs with given vertex degree distribution and edge strength distribution. We demonstrate the emergence of collective oscillations in the style of brains.

  12. Particle tagging and its implications for stellar population dynamics

    CERN Document Server

    Bret, Theo Le; Cooper, Andrew P; Frenk, Carlos; Zolotov, Adi; Brooks, Alyson M; Governato, Fabio; Parry, Owen H

    2015-01-01

    We establish a controlled comparison between the properties of galactic stellar halos obtained with hydrodynamical simulations and with `particle tagging'. Tagging is a fast way to obtain stellar population dynamics: instead of tracking gas and star formation, it `paints' stars directly onto a suitably defined subset of dark matter particles in a collisionless, dark-matter-only simulation.Our study shows that there are conditions under which particle tagging generates good fits to the hydrodynamical stellar density profiles of a central Milky-Way-like galaxy and its most prominent substructure. Phase-space diffusion processes are crucial to reshaping the distribution of stars in infalling spheroidal systems and hence the final stellar halo. We conclude that the success of any particular tagging scheme hinges on this diffusion being taken into account, at a minimum by making use of `live' tagging schemes, in which particles are regularly tagged throughout the evolution of a galaxy.

  13. Mean-field games with logistic population dynamics

    KAUST Repository

    Gomes, Diogo A.

    2013-12-01

    In its standard form, a mean-field game can be defined by coupled system of equations, a Hamilton-Jacobi equation for the value function of agents and a Fokker-Planck equation for the density of agents. Traditionally, the latter equation is adjoint to the linearization of the former. Since the Fokker-Planck equation models a population dynamic, we introduce natural features such as seeding and birth, and nonlinear death rates. In this paper we analyze a stationary meanfield game in one dimension, illustrating various techniques to obtain regularity of solutions in this class of systems. In particular we consider a logistic-type model for birth and death of the agents which is natural in problems where crowding affects the death rate of the agents. The introduction of these new terms requires a number of new ideas to obtain wellposedness. In a forthcoming publication we will address higher dimensional models. ©2013 IEEE.

  14. Replication, Communication, and the Population Dynamics of Scientific Discovery.

    Directory of Open Access Journals (Sweden)

    Richard McElreath

    Full Text Available Many published research results are false (Ioannidis, 2005, and controversy continues over the roles of replication and publication policy in improving the reliability of research. Addressing these problems is frustrated by the lack of a formal framework that jointly represents hypothesis formation, replication, publication bias, and variation in research quality. We develop a mathematical model of scientific discovery that combines all of these elements. This model provides both a dynamic model of research as well as a formal framework for reasoning about the normative structure of science. We show that replication may serve as a ratchet that gradually separates true hypotheses from false, but the same factors that make initial findings unreliable also make replications unreliable. The most important factors in improving the reliability of research are the rate of false positives and the base rate of true hypotheses, and we offer suggestions for addressing each. Our results also bring clarity to verbal debates about the communication of research. Surprisingly, publication bias is not always an obstacle, but instead may have positive impacts-suppression of negative novel findings is often beneficial. We also find that communication of negative replications may aid true discovery even when attempts to replicate have diminished power. The model speaks constructively to ongoing debates about the design and conduct of science, focusing analysis and discussion on precise, internally consistent models, as well as highlighting the importance of population dynamics.

  15. Replication, Communication, and the Population Dynamics of Scientific Discovery.

    Science.gov (United States)

    McElreath, Richard; Smaldino, Paul E

    2015-01-01

    Many published research results are false (Ioannidis, 2005), and controversy continues over the roles of replication and publication policy in improving the reliability of research. Addressing these problems is frustrated by the lack of a formal framework that jointly represents hypothesis formation, replication, publication bias, and variation in research quality. We develop a mathematical model of scientific discovery that combines all of these elements. This model provides both a dynamic model of research as well as a formal framework for reasoning about the normative structure of science. We show that replication may serve as a ratchet that gradually separates true hypotheses from false, but the same factors that make initial findings unreliable also make replications unreliable. The most important factors in improving the reliability of research are the rate of false positives and the base rate of true hypotheses, and we offer suggestions for addressing each. Our results also bring clarity to verbal debates about the communication of research. Surprisingly, publication bias is not always an obstacle, but instead may have positive impacts-suppression of negative novel findings is often beneficial. We also find that communication of negative replications may aid true discovery even when attempts to replicate have diminished power. The model speaks constructively to ongoing debates about the design and conduct of science, focusing analysis and discussion on precise, internally consistent models, as well as highlighting the importance of population dynamics.

  16. Sensory dynamics of visual hallucinations in the normal population

    Science.gov (United States)

    Pearson, Joel; Chiou, Rocco; Rogers, Sebastian; Wicken, Marcus; Heitmann, Stewart; Ermentrout, Bard

    2016-01-01

    Hallucinations occur in both normal and clinical populations. Due to their unpredictability and complexity, the mechanisms underlying hallucinations remain largely untested. Here we show that visual hallucinations can be induced in the normal population by visual flicker, limited to an annulus that constricts content complexity to simple moving grey blobs, allowing objective mechanistic investigation. Hallucination strength peaked at ~11 Hz flicker and was dependent on cortical processing. Hallucinated motion speed increased with flicker rate, when mapped onto visual cortex it was independent of eccentricity, underwent local sensory adaptation and showed the same bistable and mnemonic dynamics as sensory perception. A neural field model with motion selectivity provides a mechanism for both hallucinations and perception. Our results demonstrate that hallucinations can be studied objectively, and they share multiple mechanisms with sensory perception. We anticipate that this assay will be critical to test theories of human consciousness and clinical models of hallucination. DOI: http://dx.doi.org/10.7554/eLife.17072.001 PMID:27726845

  17. Dynamic equilibrium of reconstituting hematopoietic stem cell populations.

    Science.gov (United States)

    O'Quigley, John

    2010-12-01

    Clonal dominance in hematopoietic stem cell populations is an important question of interest but not one we can directly answer. Any estimates are based on indirect measurement. For marked populations, we can equate empirical and theoretical moments for binomial sampling, in particular we can use the well-known formula for the sampling variation of a binomial proportion. The empirical variance itself cannot always be reliably estimated and some caution is needed. We describe the difficulties here and identify ready solutions which only require appropriate use of variance-stabilizing transformations. From these we obtain estimators for the steady state, or dynamic equilibrium, of the number of hematopoietic stem cells involved in repopulating the marrow. The calculations themselves are not too involved. We give the distribution theory for the estimator as well as simple approximations for practical application. As an illustration, we rework on data recently gathered to address the question as to whether or not reconstitution of marrow grafts in the clinical setting might be considered to be oligoclonal.

  18. Far from random: dynamical groupings among the NEO population

    CERN Document Server

    Marcos, C de la Fuente

    2016-01-01

    Among the near-Earth object (NEO) population there are comets and active asteroids which are sources of fragments that initially move together; in addition, some NEOs follow orbits temporarily trapped in a web of secular resonances. These facts contribute to increasing the risk of meteoroid strikes on Earth, making its proper quantification difficult. The identification and subsequent study of groups of small NEOs that appear to move in similar trajectories are necessary steps in improving our understanding of the impact risk associated with meteoroids. Here, we present results of a search for statistically significant dynamical groupings among the NEO population. Our Monte Carlo-based methodology recovers well-documented groupings like the Taurid Complex or the one resulting from the split comet 73P/Schwassmann-Wachmann 3, and new ones that may have been the source of past impacts. Among the most conspicuous are the Mjolnir and Ptah groups, perhaps the source of recent impact events like Almahata Sitta and C...

  19. Far from random: dynamical groupings among the NEO population

    Science.gov (United States)

    de la Fuente Marcos, C.; de la Fuente Marcos, R.

    2016-03-01

    Among the near-Earth object (NEO) population, there are comets and active asteroids which are sources of fragments that initially move together; in addition, some NEOs follow orbits temporarily trapped in a web of secular resonances. These facts contribute to increasing the risk of meteoroid strikes on Earth, making its proper quantification difficult. The identification and subsequent study of groups of small NEOs that appear to move in similar trajectories are necessary steps in improving our understanding of the impact risk associated with meteoroids. Here, we present results of a search for statistically significant dynamical groupings among the NEO population. Our Monte Carlo-based methodology recovers well-documented groupings like the Taurid Complex or the one resulting from the split comet 73P/Schwassmann-Wachmann 3, and new ones that may have been the source of past impacts. Among the most conspicuous are the Mjolnir and Ptah groups, perhaps the source of recent impact events like Almahata Sitta and Chelyabinsk, respectively. Meteoroid 2014 AA, that hit the Earth on 2014 January 2, could have its origin in a marginally significant grouping associated with Bennu. We find that most of the substructure present within the orbital domain of the NEOs is of resonant nature, probably induced by secular resonances and the Kozai mechanism that confine these objects into specific paths with well-defined perihelia.

  20. Perceptions of stakeholders about nontraditional cookstoves in Honduras

    Science.gov (United States)

    Ramirez, Sebastian; Dwivedi, Puneet; Bailis, Robert; Ghilardi, Adrian

    2012-12-01

    We used SWOT-AHP (strengths, weaknesses, opportunities and threats-analytical hierarchy process) technique to measure perceptions of four stakeholder groups: employees, local promoters, community leaders and end-users, about a nontraditional cookstove (NTCS) in Honduras. These stakeholder groups are part of an ongoing NTCS dissemination project led by Proyecto Mirador. We found that all stakeholder groups have a positive perception about the existing NTCS. Employees and local promoters stakeholder groups share similar perceptions. Smokeless cooking was selected as a prime strength, closely followed by reduction in forest logging and greenhouse gas emissions by all stakeholder groups. Availability of financial resources and responsible management were identified as crucial opportunities. Time spent in wood preparation and NTCS maintenance were identified as principal weaknesses. A long waiting time between a request and installation of NTCS and the risk of losing existing financial resources were acknowledged as major threats. Design improvements that can reduce maintenance and wood preparation time, a secure long-term source of funding through a market mechanism or direct/indirect government involvement, and early execution of pending orders will help in increasing adoption of NTCSs in rural Honduras.

  1. New geochemical investigations in Platanares and Azacualpa geothermal sites (Honduras)

    Science.gov (United States)

    Barberi, Franco; Carapezza, Maria Luisa; Cioni, Roberto; Lelli, Matteo; Menichini, Matia; Ranaldi, Massimo; Ricci, Tullio; Tarchini, Luca

    2013-05-01

    Platanares and Azacualpa geothermal sites of Honduras are located in an inner part of the Caribbean Plate far from the active volcanic front of Central America. Here geology indicates that there are not the conditions for the occurrence of shallow magmatic heat sources for high-enthalpy geothermal resources. Geothermal perspectives are related to the possibility of a deep circulation of meteoric water along faults and the storage of the heated fluid in fractured permeable reservoirs. Geochemical geothermometers indicate a temperature for the deeper part of the geothermal reservoir close to 200 °C for Platanares and of 150-170 °C for Azacualpa. Calcite scaling, with subordinate silica deposition has to be expected in both sites. CO2 soil flux investigations have been carried out in both areas and reveal the presence of positive anomalies likely corresponding to the presence at depth of fractured degassing geothermal reservoirs. Compared with the geothermal areas of Central Italy whose reservoirs are hosted in carbonate rocks, e.g. Latera (Chiodini et al., 2007), the CO2 soil flux measured in Honduras is significantly lower (mean of 17 g/m2day at Platanares and of 163 g/m2day at Azacualpa) probably because of the dominant silicate nature of the deep reservoirs.

  2. Developing a longitudinal cancer nursing education program in Honduras.

    Science.gov (United States)

    Sheldon, Lisa Kennedy; Wise, Barbara; Carlson, Julie R; Dowds, Cynthia; Sarchet, Vanessa; Sanchez, Jose Angel

    2013-12-01

    The present paper is a longitudinal study which aims to develop and deliver cancer nursing education conferences in Honduras using volunteer nurse educators. This program intends to (1) perform site assessments of work environments and resources for cancer care in Honduras, (2) develop cancer nursing education programs, (3) survey conference participants continuing education needs, (4) deliver cancer nursing education conferences, and (5) share data with local and global partners for future cancer programs. The study draws on a longitudinal program development with site assessments, data collection, and educational conferences at two time points. Assessments and surveys were used for conference development and delivery by volunteer nurse educators. Site assessments and conferences were delivered twice. Data were collected regarding assessments and surveys to inform program development. Survey data revealed that 65 % had internet access. Participants desired more information about handling of chemotherapy, symptom management, and palliative care. Volunteer nurse educators perform site assessments and develop educational programming for cancer nurses. Local and global partners should explore internet-based programs between site visits to create sustainable education programs.

  3. Sustainable energy policy in Honduras. Diagnosis and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Wilfredo C. [National Directorate of Energy, Tegucigalpa (MDC), Honduras, Central America (United States); Universidad Nacional Autonoma de Honduras, Facultad de Ciencias, Escuela de Fisica, Tegucigalpa (MDC), Honduras, Central America (United States); Ojeda, Osvaldo A. [Universidad Nacional de la Patagonia San Juan Bosco (Argentina); Flores, Marco A.; Rivas, Francisco R. [Universidad Nacional Autonoma de Honduras, Facultad de Ciencias, Escuela de Fisica, Tegucigalpa (MDC), Honduras, Central America (United States)

    2011-02-15

    In view of having a still unexploited potential of natural resources available for clean energy and the possibility of using the regional electricity market in Central America, Honduras has several potential energy sources. The growing dependence on oil and the imminent increase in international prices of fossil fuels, coupled with the necessity of changing the energy sector arrangement, the State of Honduras has taken the lead for the development of a long-term sustainable energy policy. This energy policy must be able to develop various energy sources and guide both, the government and the private sector, to the planning and development of alternative energy sources and sustainable growth of the Honduran economy. In this paper, the various energy diagnoses and the potential for changing the Honduran energy mix are presented, as well as the investment required for sustainable management of the energy sector. Furthermore, the objectives of the energy policy and plan up to the year 2030 are presented, outlining the investment possibilities for the energy sector development, showing their costs and timeframes. (author)

  4. Catalog of known hot springs and thermal place names for Honduras

    Energy Technology Data Exchange (ETDEWEB)

    Finch, R.C.

    1986-08-01

    Thermal place names were compiled from all 1:50,000 topographic quadrangle maps for the Republic of Honduras as of July 1986, from other published maps, and from several sources of unpublished data. Known hot spring sites include those visited by Empresa Nacional de Energia Electrica (Honduras) geologists, sites visited by Los Alamos geologists in 1985, and other sites known to R.C. Finch. The number of known hot spring sites in Honduras with temperatures >30/sup 0/C is 125. In addition, 56 thermal sites are suspected on the basis of thermal place names. The total number of geothermal sites, known and suspected, is 181.

  5. Population dynamics of caribou herds in southwestern Alaska

    Directory of Open Access Journals (Sweden)

    Patrick Valkenburg

    2003-04-01

    Full Text Available The five naturally occurring and one transplanted caribou (Rangifer tarandus granti herd in southwestern Alaska composed about 20% of Alaska's caribou population in 2001. All five of the naturally occurring herds fluctuated considerably in size between the late 1800s and 2001 and for some herds the data provide an indication of long-term periodic (40-50 year fluctuations. At the present time, the Unimak (UCH and Southern Alaska Peninsula (SAP are recovering from population declines, the Northern Alaska Peninsula Herd (NAP appears to be nearing the end of a protracted decline, and the Mulchatna Herd (MCH appears to now be declining after 20 years of rapid growth. The remaining naturally occurring herd (Kilbuck has virtually disappeared. Nutrition had a significant effect on the size of 4-month-old and 10-month-old calves in the NAP and the Nushagak Peninsula Herd (NPCH and probably also on population growth in at least 4 (SAP, NAP, NPCH, and MCH of the six caribou herds in southwestern Alaska. Predation does not appear to be sufficient to keep caribou herds in southwestern Alaska from expanding, probably because rabies is endemic in red foxes (Vulpes vulpes and is periodically transferred to wolves (Canis lupus and other canids. However, we found evidence that pneumonia and hoof rot may result in significant mortality of caribou in southwestern Alaska, whereas there is no evidence that disease is important in the dynamics of Interior herds. Cooperative conservation programs, such as the Kilbuck Caribou Management Plan, can be successful in restraining traditional harvest and promoting growth in caribou herds. In southwestern Alaska we also found evidence that small caribou herds can be swamped and assimilated by large herds, and fidelity to traditional calving areas can be lost.

  6. Modelling multi-pulse population dynamics from ultrafast spectroscopy.

    Directory of Open Access Journals (Sweden)

    Luuk J G W van Wilderen

    Full Text Available Current advanced laser, optics and electronics technology allows sensitive recording of molecular dynamics, from single resonance to multi-colour and multi-pulse experiments. Extracting the occurring (bio- physical relevant pathways via global analysis of experimental data requires a systematic investigation of connectivity schemes. Here we present a Matlab-based toolbox for this purpose. The toolbox has a graphical user interface which facilitates the application of different reaction models to the data to generate the coupled differential equations. Any time-dependent dataset can be analysed to extract time-independent correlations of the observables by using gradient or direct search methods. Specific capabilities (i.e. chirp and instrument response function for the analysis of ultrafast pump-probe spectroscopic data are included. The inclusion of an extra pulse that interacts with a transient phase can help to disentangle complex interdependent pathways. The modelling of pathways is therefore extended by new theory (which is included in the toolbox that describes the finite bleach (orientation effect of single and multiple intense polarised femtosecond pulses on an ensemble of randomly oriented particles in the presence of population decay. For instance, the generally assumed flat-top multimode beam profile is adapted to a more realistic Gaussian shape, exposing the need for several corrections for accurate anisotropy measurements. In addition, the (selective excitation (photoselection and anisotropy of populations that interact with single or multiple intense polarised laser pulses is demonstrated as function of power density and beam profile. Using example values of real world experiments it is calculated to what extent this effectively orients the ensemble of particles. Finally, the implementation includes the interaction with multiple pulses in addition to depth averaging in optically dense samples. In summary, we show that mathematical

  7. Cryptic population dynamics: rapid evolution masks trophic interactions.

    Directory of Open Access Journals (Sweden)

    Takehito Yoshida

    2007-09-01

    Full Text Available Trophic relationships, such as those between predator and prey or between pathogen and host, are key interactions linking species in ecological food webs. The structure of these links and their strengths have major consequences for the dynamics and stability of food webs. The existence and strength of particular trophic links has often been assessed using observational data on changes in species abundance through time. Here we show that very strong links can be completely missed by these kinds of analyses when changes in population abundance are accompanied by contemporaneous rapid evolution in the prey or host species. Experimental observations, in rotifer-alga and phage-bacteria chemostats, show that the predator or pathogen can exhibit large-amplitude cycles while the abundance of the prey or host remains essentially constant. We know that the species are tightly linked in these experimental microcosms, but without this knowledge, we would infer from observed patterns in abundance that the species are weakly or not at all linked. Mathematical modeling shows that this kind of cryptic dynamics occurs when there is rapid prey or host evolution for traits conferring defense against attack, and the cost of defense (in terms of tradeoffs with other fitness components is low. Several predictions of the theory that we developed to explain the rotifer-alga experiments are confirmed in the phage-bacteria experiments, where bacterial evolution could be tracked. Modeling suggests that rapid evolution may also confound experimental approaches to measuring interaction strength, but it identifies certain experimental designs as being more robust against potential confounding by rapid evolution.

  8. Population dynamics and monitoring applied to decision-making

    Directory of Open Access Journals (Sweden)

    Conroy, M. J.

    2004-06-01

    influence diagrams to capture the stochastic, temporal processes of managing cheetah population in Kenya. The model predicts likely anagement decisions made by various actors within these countries, (e.g., the President, the Environmental Protection Agency, and rural residents and the resulting probability of cheetah extinction following these decisions. By approaching the problem in both its political and ecological contexts one avoids consideration of decisions that, while beneficial from a purely conservation point of view, are unlikely to be implemented because of conflicting political objectives. Haas’s analysis demonstrates both the promise and challenges of this type of modeling, and he offers suggestions for overcoming inherent technical difficulties such as model calibration. The second paper, by Simon Hoyle and Mark Maunder (Hoyle & Maunder, 2004, uses a Bayesian approach to model population dynamics and the effects of commercial fishing bycatch for the eastern Pacific Ocean spotted dolphin (Stenella attenuata. Their paper provides a good example of why Bayesian analysis is particularly suited to many management problems. Namely, because it allows the integration of disparate pieces of monitoring data in the simultaneous estimation of population parameters; allows forincorporation of expert judgment and data from other systems and species; and provides for explicit consideration of uncertainty in decision–making. Alternative management scenarios can then be explored via forward simulations. In the third paper, Chris Fonnesbeck and Mike Conroy (Fonnesbeck & Conroy, 2004 present an integrated approach for estimating parameters and predicting abundance of American black duck (Anas rubripes populations. They also employ a ayesian approach and overcome some of the computational challenges by using Markov chain–Monte Carlo methods. Ring–recovery and harvest data are used to estimate fall age ratios under alternative reproductive models. These in turn are used to

  9. Drug consumption by medical students in tegucigalpa, Honduras Uso de drogas entre estudiantes de medicina, tegucigalpa, Honduras O uso de drogas entre estudantes de medicina em tegucigalpa, Honduras

    Directory of Open Access Journals (Sweden)

    Juana Carolina Buchanan

    2008-08-01

    Full Text Available The use of drugs, in Honduras, involves 25% of college students. The most used substances include legal and recreational drugs, such as alcohol. This study aimed to identify the use of drugs and socio-demographic factors in a sample of 260 medical students. RESULTS: Average age of 20 years old, unemployed and religious women, single, with no children. Alcohol was the most consumed drug in the last six months for recreational purposes. The following stimulants were frequently consumed: caffeine, mate herb tea, energetic drinks and Coke. Drugs like marijuana, cocaine, valium and sedatives were used in smaller proportions. The reasons reported by women were: to alleviate tiredness and improve their academic performance. The men's reasons were recreation and to alleviate psychological tension. This research has implications for the development of drugs prevention programs in universities.En Honduras, el uso de drogas está presente en el 25% de estudiantes universitarios. Entre las drogas de mayor consumo están las lícitas y de uso recreacional, las bebidas alcohólicas siendo las lícitas y de uso recreacional, como el caso das bebidas alcohólicas. Ese estudio tuvo como propósito identificar el consumo de drogas y los factores sociodemográficos en una muestra de 260 estudiantes de medicina. RESULTADOS: edad media 20 años, mujeres, solteros, no tiene hijos, no trabajan, profesan religión. La droga más utilizada en los últimos seis meses es el alcohol, con consumo recreacional. Los estimulantes de consumo frecuente: la cafeína, el mate; las bebidas energizantes, la coca-cola; y las drogas ilicitas como la marihuana, la cocaína, el valium y los inductores del sueño en menores proporciones. Las razones de uso para mujeres fueron: aliviar el cansancio, mejorar el rendimiento académico; y para varones: divertirse y aliviar tensiones psicológicas. Esta investigación tiene implicaciones en el desarrollo de programas preventivos del uso de

  10. Population dynamics of Borrelia burgdorferi in Lyme disease

    Directory of Open Access Journals (Sweden)

    Sebastian Christoph Binder

    2012-03-01

    Full Text Available Many chronic inflammatory diseases are known to be caused by persistent bacterial or viral infections. A well-studied example is the tick-borne infection by the gram-negative Spirochaetes of the genus Borrelia in humans and other mammals, causing severe symptoms of chronic inflammation and subsequent tissue damage (Lyme Disease, particularly in large joints and the central nervous system, but also in the heart and other tissues of untreated patients. Although killed efficiently by human phagocytic cells in vitro, Borrelia exhibits a remarkably high infectivity in mice and men. In experimentally infected mice, the first immune response almost clears the infection. However, approximately one week post infection, the bacterial population recovers and reaches an even larger size before entering the chronic phase. We developed a mathematical model describing the bacterial growth and the immune response against Borrelia burgdorferi in the C3H mouse strain that has been established as an experimental model for Lyme disease. The peculiar dynamics of the infection exclude two possible mechanistic explanations for the regrowth of the almost cleared bacteria. Neither the hypothesis of bacterial dissemination to different tissue nor a limitation of phagocytic capacity were compatible with experiment. The mathematical model predicts that Borrelia recovers from the strong initial immune response by the regrowth of an immune-resistant sub-population of the bacteria. The chronic phase appears as an equilibration of bacterial growth and adaptive immunity. This result has major implications for the development of the chronic phase of Borrelia infections as well as on potential protective clinical interventions.

  11. First record of the invasive Asian fish tapeworm Bothriocephalus acheilognathi in Honduras, Central America

    Directory of Open Access Journals (Sweden)

    Salgado-Maldonado Guillermo

    2015-01-01

    Full Text Available This paper provides the first report of the invasive Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934, in Honduras. The cestode was found in Profundulus portillorum (Cyprinodontiformes: Profundulidae, which represents a new host record, and which is a member of a genus faced with a variety of conservation challenges, now potentially complicated by the presence of this pathogenic cestode. Nearly complete sequence data from the ITS-1 5.8S and ITS-2 regions corroborate the determination based on morphological characteristics. Several species of carp were introduced to Honduras for aquaculture purposes in the early 1980s and the presence of the Asian fish tapeworm in Honduras may be related to these introductions. In addition, this report documents the currently known geographical distribution of this parasite in Central America, first recorded from Panamá and now from Honduras.

  12. First record of the invasive Asian fish tapeworm Bothriocephalus acheilognathi in Honduras, Central America.

    Science.gov (United States)

    Salgado-Maldonado, Guillermo; Matamoros, Wilfredo A; Kreiser, Brian R; Caspeta-Mandujano, Juan Manuel; Mendoza-Franco, Edgar F

    2015-01-01

    This paper provides the first report of the invasive Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934, in Honduras. The cestode was found in Profundulus portillorum (Cyprinodontiformes: Profundulidae), which represents a new host record, and which is a member of a genus faced with a variety of conservation challenges, now potentially complicated by the presence of this pathogenic cestode. Nearly complete sequence data from the ITS-1 5.8S and ITS-2 regions corroborate the determination based on morphological characteristics. Several species of carp were introduced to Honduras for aquaculture purposes in the early 1980s and the presence of the Asian fish tapeworm in Honduras may be related to these introductions. In addition, this report documents the currently known geographical distribution of this parasite in Central America, first recorded from Panamá and now from Honduras.

  13. Elementary Schools in Rural Honduras. Problems in Exporting Environmental Education Models from the United States.

    Science.gov (United States)

    Ham, Sam H.; Castillo, Lizeth

    1990-01-01

    Presented is a study designed to determine the best approaches for developing environmental education and teacher training materials for schools in Honduras. Results dispute the value of materials produced in the United States for use in developing nations. (CW)

  14. Clinical Features and Neurologic Complications of Children Hospitalized With Chikungunya Virus in Honduras.

    Science.gov (United States)

    Samra, José A; Hagood, Nancy L; Summer, Andrea; Medina, Marco T; Holden, Kenton R

    2017-07-01

    The first case of Chikungunya virus in Honduras was identified in 2014. The virus has spread widely across Honduras via the Aedes aegypti mosquito, leading to an outbreak of Chikungunya virus (CHIKV) in 2015 that significantly impacted children. A retrospective chart review of 235 children diagnosed with CHIKV and admitted to the National Autonomous University of Honduras Hospital Escuela (Hospital Escuela) in Tegucigalpa, Honduras, was accomplished with patients who were assessed for clinical features and neurologic complications. Of 235 children admitted to Hospital Escuela with CHIKV, the majority had symptoms of fever, generalized erythematous rash, and irritability. Fourteen percent had clinical arthritis. Ten percent of patients had seizures. Six percent had meningoencephalitis. There were 2 childhood deaths during the course of this study, one from meningoencephalitis and another from myocarditis. Chikungunya virus can cause severe complications in children, the majority of which impact the central nervous system.

  15. POPULATION DYNAMICS OF AMBIENT AND ALTERED EARTHWORM COMMUNITIES IN ROW-CROP AGROECOSYSTEMS IN OHIO, USA

    Science.gov (United States)

    Although earthworms are known to influence agroecosystem processes, there are relatively few long-term studies addressing population dynamics under cropping systems in which earthworm populations were intentionally altered. We assessed earthworm communities from fall 1994 to spr...

  16. Density dependence and population dynamics of black rhinos (Diceros bicornis michaeli) in Kenya's rhino sanctuaries

    NARCIS (Netherlands)

    Ouma, B.O.; Amin, R.; Langevelde, van F.; Leader-Williams, N.

    2010-01-01

    Density-dependent feedback mechanisms provide insights into the population dynamics and interactions of large herbivores with their ecosystem. Sex ratio also has particularly important implications for growth rates of many large mammal populations through its influence on reproductive potential.

  17. Fine-scale population dynamics in a marine fish species inferred from dynamic state-space models.

    Science.gov (United States)

    Rogers, Lauren A; Storvik, Geir O; Knutsen, Halvor; Olsen, Esben M; Stenseth, Nils C

    2017-07-01

    Identifying the spatial scale of population structuring is critical for the conservation of natural populations and for drawing accurate ecological inferences. However, population studies often use spatially aggregated data to draw inferences about population trends and drivers, potentially masking ecologically relevant population sub-structure and dynamics. The goals of this study were to investigate how population dynamics models with and without spatial structure affect inferences on population trends and the identification of intrinsic drivers of population dynamics (e.g. density dependence). Specifically, we developed dynamic, age-structured, state-space models to test different hypotheses regarding the spatial structure of a population complex of coastal Atlantic cod (Gadus morhua). Data were from a 93-year survey of juvenile (age 0 and 1) cod sampled along >200 km of the Norwegian Skagerrak coast. We compared two models: one which assumes all sampled cod belong to one larger population, and a second which assumes that each fjord contains a unique population with locally determined dynamics. Using the best supported model, we then reconstructed the historical spatial and temporal dynamics of Skagerrak coastal cod. Cross-validation showed that the spatially structured model with local dynamics had better predictive ability. Furthermore, posterior predictive checks showed that a model which assumes one homogeneous population failed to capture the spatial correlation pattern present in the survey data. The spatially structured model indicated that population trends differed markedly among fjords, as did estimates of population parameters including density-dependent survival. Recent biomass was estimated to be at a near-record low all along the coast, but the finer scale model indicated that the decline occurred at different times in different regions. Warm temperatures were associated with poor recruitment, but local changes in habitat and fishing pressure may

  18. Geophysical Investigation for Groundwater Resources at the Soto Cano Air Base, Honduras

    Science.gov (United States)

    1992-12-01

    America, Publicaciones Geologicas del ICAITI, No. V, pp. 31-42. Fakundiny, R.H., 1970, Geology of the El Rosario Quadrangle, Honduras, Central...freshwater aquifers in northeastern Missouri, Geophysics, vol. 39, p. 340. Interpex, Ltd., 1988. Program Resix Plus and User’s Manual , Interpex Ltd., P.O...Central. Muehlberger, W. R., 1976, The Honduras Depression, Publicaciones Geologicas del ICAITI, No. V, 42 pp. Weyl, R., 1980, Geology of Central

  19. Intertidal population genetic dynamics at a microgeographic seascape scale.

    Science.gov (United States)

    Hu, Zi-Min

    2013-06-01

    The intertidal community is among the most physically harsh niches on earth, with highly heterogeneous environmental and biological factors that impose strong habitat selection on population abundance, genetic connectivity and ecological adaptation of organisms in nature. However, most genetic studies to date have concentrated on the influence of basin-wide or regional marine environments (e.g. habitat discontinuities, oceanic currents and fronts, and geographic barriers) on spatiotemporal distribution and composition of intertidal invertebrates having planktonic stages or long-distance dispersal capability. Little is known about sessile marine organisms (e.g. seaweeds) in the context of topographic tidal gradients and reproductive traits at the microgeographic scale. In this issue of Molecular Ecology, Krueger-Hadfield et al. () implemented an elaborate sampling strategy with red seaweed (Chondrus crispus) from a 90-m transect stand near Roscoff and comprehensively detected genome-scale genetic differentiation and biases in ploidy level. This study not only revealed that tidal height resulted in genetic differentiation between high- and low-shore stands and restricted the genetic exchange within the high-shore habitat, but also demonstrated that intergametophytic nonrandom fertilization in C. crispus can cause significant deviation from Hardy-Weinberg equilibrium. Such new genetic insights highlight the importance of microgeographic genetic dynamics and life history characteristics for better understanding the evolutionary processes of speciation and diversification of intertidal marine organisms. © 2013 John Wiley & Sons Ltd.

  20. A spatial ecosystem and populations dynamics model (SEAPODYM) Modeling of tuna and tuna-like populations

    Science.gov (United States)

    Lehodey, Patrick; Senina, Inna; Murtugudde, Raghu

    2008-09-01

    An enhanced version of the spatial ecosystem and population dynamics model SEAPODYM is presented to describe spatial dynamics of tuna and tuna-like species in the Pacific Ocean at monthly resolution over 1° grid-boxes. The simulations are driven by a bio-physical environment predicted from a coupled ocean physical-biogeochemical model. This new version of SEAPODYM includes expanded definitions of habitat indices, movements, and natural mortality based on empirical evidences. A thermal habitat of tuna species is derived from an individual heat budget model. The feeding habitat is computed according to the accessibility of tuna predator cohorts to different vertically migrating and non-migrating micronekton (mid-trophic) functional groups. The spawning habitat is based on temperature and the coincidence of spawning fish with presence or absence of predators and food for larvae. The successful larval recruitment is linked to spawning stock biomass. Larvae drift with currents, while immature and adult tuna can move of their own volition, in addition to being advected by currents. A food requirement index is computed to adjust locally the natural mortality of cohorts based on food demand and accessibility to available forage components. Together these mechanisms induce bottom-up and top-down effects, and intra- (i.e. between cohorts) and inter-species interactions. The model is now fully operational for running multi-species, multi-fisheries simulations, and the structure of the model allows a validation from multiple data sources. An application with two tuna species showing different biological characteristics, skipjack ( Katsuwonus pelamis) and bigeye ( Thunnus obesus), is presented to illustrate the capacity of the model to capture many important features of spatial dynamics of these two different tuna species in the Pacific Ocean. The actual validation is presented in a companion paper describing the approach to have a rigorous mathematical parameter optimization

  1. Dynamics of Betula ermanni population in subalpine vegetation in Changbai Mountain, Northeast China

    Institute of Scientific and Technical Information of China (English)

    Zou Chunjing; Han Shijie; Wang Xiaochun

    1999-01-01

    Betula ermanni population was divided into three groups: the upper population (2 000~2 200 m), the middle population (1 700~2000 m), and the down population (1 400~1 700 m) in Changbai Mountain. The dynamics of Betula ermanni populations in subalpine vegetation are studied and the population life table,fecundity schedule, survival curves, age structure, and fecundity curves were established. The results showed that the middle population is obviously the transition from the upper population to the down population.

  2. EVOLUTIONARY DYNAMIC MODEL OF POPULATION WITH NICHE CONSTRUCTION AND ITS APPLICATION RESEARCH

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the theories and approaches in biomechanics, the mechanism and pattern of niche construction were discussed systematically. Through establishing the spatial pattern of niche and its measuring-fitness formula, and the dynamic system models of single- and two-population with niche construction, including corresponding theoretical analysis and numerical simulation on their evolutionary dynamics of population and the mechanism of competitive coexistence, the co-evolutionary relationship between organisms and their environments was revealed. The results indicate that population dynamics is governed by positive feedback between primary ecological factors and resource content.Niche construction generates an evolutionary effect in system by influencing the fitness of population. A threshold effect exists in single population dynamic system. In dynamic system of two competitive populations, niche construction can lead to alternative competitive consequences, which may be a potential mechanism to explain the competitive coexistence of species.

  3. Drug consumption by medical students in Tegucigalpa, Honduras.

    Science.gov (United States)

    Buchanan, Juana Carolina; Pillon, Sandra Cristina

    2008-01-01

    The use of drugs, in Honduras, involves 25% of college students. The most used substances include legal and recreational drugs, such as alcohol. This study aimed to identify the use of drugs and socio-demographic factors in a sample of 260 medical students. Average age of 20 years old, unemployed and religious women, single, with no children. Alcohol was the most consumed drug in the last six months for recreational purposes. The following stimulants were frequently consumed: caffeine, mate herb tea, energetic drinks and Coke. Drugs like marijuana, cocaine, valium and sedatives were used in smaller proportions. The reasons reported by women were: to alleviate tiredness and improve their academic performance. The men's reasons were recreation and to alleviate psychological tension. This research has implications for the development of drugs prevention programs in universities.

  4. Social integration and health behavioral change in San Luis, Honduras.

    Science.gov (United States)

    McQuestion, Michael J; Quijano Calle, Ana; Drasbek, Christopher; Harkins, Thomas; Sagastume, Lourdes J

    2010-10-01

    This study explores the effects of social integration on behavioral change in the course of an intensive, community-based public health intervention. The intervention trained volunteers and mobilized local organizations to promote 16 key family health practices in rural San Luis, Honduras, during 2004 to 2006. A mixed methods approach is used. Standard household sample surveys were performed in 22 villages before and after the intervention. Eight villages were then resurveyed. A household survey, focus groups, and key informant interviews measured health behaviors and several social structural and psychosocial variables. The villages were then ranked on their mean behavioral and social integration scores. The quantitative and qualitative rankings were in close agreement (Kendall's coefficient of concordance = .707, p behavioral change. Health interventions can be made more effective by analyzing these features a priori.

  5. Structural and geophysical interpretation of Roatan Island, Honduras, Western Caribbean

    Science.gov (United States)

    Sutton, Daniel Scott

    Roatan Island is the largest of the Bay Islands of Honduras. These islands form an emergent crest off the Caribbean coast of Honduras called the Bonacca Ridge. The Bartlett Trough to the north and subsequent Bonacca Ridge were likely formed due to the transform fault system of the Motagua-Swan Islands Fault System. This fault system forms the tectonic plate boundary between the North American and Caribbean plates. Although the timing and kinematics are poorly constrained, the Bay Islands and the Bonacca Ridge were likely uplifted due to transpression along this left-lateral strike-slip system. With limited regional exposures along the adjacent tectonic boundary, this study aimed to present a structural interpretation for Roatan. This new interpretation is further explained through regional considerations for a suggested geologic history of the northwestern Caribbean. In order to better constrain the kinematics of uplift and exhumation of Roatan Island, structural, gravity, and magnetic surveys were conducted. Principal attention was directed to the structural relationship between the geologic units and their relationship to one another through deformation. Resulting geologic cross-sections from this study present the metamorphic basement exposed throughout the island to be in a normal structural order consisting of biotite schist and gneiss, with overlying units of chlorite schist, carbonate, and conglomerate. These units have relatively concordant strike and dip measurements, consistent with resultant magnetic survey readings. Additionally, large and irregular bodies of amphibolite and serpentinite throughout the island are interpreted to have been emplaced as mafic and ultra-mafic intrusions in weakness zones along Early Paleogene transform system fault planes. The interpretation and suggested geologic history from this study demonstrate the importance of transpressive tectonics both local to Roatan and regionally throughout geologic history. Consideration of

  6. Population Dynamics and Cost-Benefit Analysis. An Attempt to Relate Population Dynamics via Lifetime Reproductive Success to Short-Term Decisions

    NARCIS (Netherlands)

    Tinbergen, J.M.; Balen, J.H. van; Drent, P.J.; Cavé, A.J.; Mertens, J.A.L.; Boer-Hazewinkel, J. den

    1987-01-01

    1. The aim of this article is to explore whether cost-benefit analysis of behaviour may help to understand the population dynamics of a species. The Great Tit is taken as an example. 2. The lifetime reproductive success in different populations of Great Tits amounts from 0.7 (Hoge Veluwe, Wytham) to

  7. A new scorpion species of genus Diplocentrus Peters, 1861 (Scorpiones: Diplocentridae) endemic to Islas de la Bahia, Honduras.

    Science.gov (United States)

    Sagastume-Espinoza, Kevin O; Longhorn, Stuart J; Santibáñez-López, Carlos E

    2015-07-01

    Three species of genus Diplocentrus are found in north-northwestern Honduras. These species represent the southern east limits of Diplocentrus' distribution. In recent years, a broad survey of arachnids in Honduras has yielded a collection of several specimens of an undescribed species from two islands in northern Honduras. This new species represents the second species of the genus inhabiting an island. The present contribution describes this new species, and compares it against its most similar relatives. A dichotomous key for the identification of the species of Diplocentrus in Honduras is also included.

  8. Mosquito population dynamic (diptera: culicidae in a eutrophised dam

    Directory of Open Access Journals (Sweden)

    ED. Wermelinger

    Full Text Available This study observed the mosquito population in a rural eutrophised dam. Larvae of L3 and L4 stages and pupae were dipped out during twelve month collections and the reared to the adult stage for identification. The collections were done along nine metres from the edge of the dam divided in three parts (P1, P2 and P3, each part being 3 m long. P1 did not have vegetation (grass along its edge,which would reach or sink into the water to promote some shade on the marginal water. A total of 217 adults of four species was identified with the following constancies and frequencies: Culex quinquefasciatus (Say, 1823 (83% and 40.6%, Anopheles (Nyssorhynchus evansae (Brèthes, 1926 (92% and 26.7%, Anopheles (Nyssorhynchus rangeli (Gabaldon, Cova Garcia and Lopez, 1940 (83% and 14.3% and Culex nigripalpus (Theobald, 1901 (33% and 18.4%. C. quinquefasciatus, A. evansae, A. rangeli and C. nigripalpus were more frequent in the quarters Nov./Dec./Jan. (85.7%, May/June/July (75%, Aug./Sept./Oct. (29.4% and Aug./Sept./Oct. (23.5% particularly in the months of December (88.4% Sept.tember (48.94, (38.3 and August (47.62 respectively. The presence of C. quinquefasciatus and the high incidence of Daphinia sp. and also the levels of Organic Nitrogen (0.28 mg/L and of total Phosphorus (0.02 mg/L are indications of the eutrophication of the dam. There was a difference regarding the total of Anopheles (A. avansae + A. rangeli and Culex species (C. quinquefasciatus + C. nigripalpis between P1 and P2 (χ² = 0.0097, P1 and P3 (χ² = 0.0005, but not between P2 and P3 (χ² = 0.2045.The high C. quinquefasciatus constancy and frequency were confirmed to be a good biological indicator for a eutrophised environment and A. evansae showed a good potential for this environment. Vegetation can be an important factor for anopheline population dynamic also in eutrophic breeding sites.

  9. Mosquito population dynamic (Diptera: Culicidae) in a eutrophised dam.

    Science.gov (United States)

    Wermelinger, E D; Benigno, C V; Machado, R N M; Cabello, P H; Meira, A M; Ferreira, A P; Zanuncio, J C

    2012-11-01

    This study observed the mosquito population in a rural eutrophised dam. Larvae of L3 and L4 stages and pupae were dipped out during twelve month collections and the reared to the adult stage for identification. The collections were done along nine metres from the edge of the dam divided in three parts (P1, P2 and P3), each part being 3 m long. P1 did not have vegetation (grass) along its edge,which would reach or sink into the water to promote some shade on the marginal water. A total of 217 adults of four species was identified with the following constancies and frequencies: Culex quinquefasciatus (Say, 1823) (83% and 40.6%), Anopheles (Nyssorhynchus) evansae (Brèthes, 1926) (92% and 26.7%), Anopheles (Nyssorhynchus) rangeli (Gabaldon, Cova Garcia and Lopez, 1940) (83% and 14.3%) and Culex nigripalpus (Theobald, 1901) (33% and 18.4%). C. quinquefasciatus, A. evansae, A. rangeli and C. nigripalpus were more frequent in the quarters Nov./Dec./Jan. (85.7%), May/June/July (75%), Aug./Sept./Oct. (29.4%) and Aug./Sept./Oct. (23.5%) particularly in the months of December (88.4%) Sept.tember (48.94), (38.3) and August (47.62) respectively. The presence of C. quinquefasciatus and the high incidence of Daphinia sp. and also the levels of Organic Nitrogen (0.28 mg/L) and of total Phosphorus (0.02 mg/L) are indications of the eutrophication of the dam. There was a difference regarding the total of Anopheles (A. avansae + A. rangeli) and Culex species (C. quinquefasciatus + C. nigripalpis) between P1 and P2 (χ(2) = 0.0097), P1 and P3 (χ(2) = 0.0005), but not between P2 and P3 (χ(2) = 0.2045).The high C. quinquefasciatus constancy and frequency were confirmed to be a good biological indicator for a eutrophised environment and A. evansae showed a good potential for this environment. Vegetation can be an important factor for anopheline population dynamic also in eutrophic breeding sites.

  10. Quantifying Salmonella population dynamics in water and biofilms.

    Science.gov (United States)

    Sha, Qiong; Vattem, Dhiraj A; Forstner, Michael R J; Hahn, Dittmar

    2013-01-01

    Members of the bacterial genus Salmonella are recognized worldwide as major zoonotic pathogens often found to persist in non-enteric environments including heterogeneous aquatic biofilms. In this study, Salmonella isolates that had been detected repeatedly over time in aquatic biofilms at different sites in Spring Lake, San Marcos, Texas, were identified as serovars Give, Thompson, Newport and -:z10:z39. Pathogenicity results from feeding studies with the nematode Caenorhabditis elegans as host confirmed that these strains were pathogenic, with Salmonella-fed C. elegans dying faster (mean survival time between 3 and 4 days) than controls, i.e., Escherichia coli-fed C. elegans (mean survival time of 9.5 days). Cells of these isolates inoculated into water at a density of up to 10(6) ml(-1) water declined numerically by 3 orders of magnitude within 2 days, reaching the detection limit of our quantitative polymerase chain reaction (qPCR)-based quantification technique (i.e., 10(3) cells ml(-1)). Similar patterns were obtained for cells in heterogeneous aquatic biofilms developed on tiles and originally free of Salmonella that were kept in the inoculated water. Cell numbers increased during the first days to more than 10(7) cells cm(-2), and then declined over time. Ten-fold higher cell numbers of Salmonella inoculated into water or into biofilm resulted in similar patterns of population dynamics, though cells in biofilms remained detectable with numbers around 10(4) cells cm(-2) after 4 weeks. Independent of detectability by qPCR, samples of all treatments harbored viable salmonellae that resembled the inoculated isolates after 4 weeks of incubation. These results demonstrate that pathogenic salmonellae were isolated from heterogeneous aquatic biofilms and that they could persist and stay viable in such biofilms in high numbers for some time.

  11. Species-specific earthworm population responses in relation to flooding dynamics in a Dutch floodplain soil

    NARCIS (Netherlands)

    Zorn, M.I.; Gestel, van C.A.M.; Eijsackers, H.J.P.

    2005-01-01

    Earthworms dominate the animal biomass in moist floodplain soils. They are known to survive long periods in aerated water, but little is known about earthworm population dynamics in floodplain systems with changing inundation frequencies. This study determined earthworm population dynamics in a floo

  12. Geographic coupling of juvenile and adult habitat shapes spatial population dynamics of a coral reef fish

    NARCIS (Netherlands)

    Huijbers, C.M.; Nagelekerken, I.; Debrot, A.O.; Jongejans, E.

    2013-01-01

    Marine spatial population dynamics are often addressed with a focus on larval dispersal, without taking into account movement behavior of individuals in later life stages. Processes occurring during demersal life stages may also drive spatial population dynamics if habitat quality is perceived diffe

  13. Exploitation of Chemical Signaling by Parasitoids: Impact on Host Population Dynamics

    NARCIS (Netherlands)

    Lof, M.E.; Gee, de M.; Dicke, M.; Gort, G.; Hemerik, L.

    2013-01-01

    Chemical information mediates species interactions in a wide range of organisms. Yet, the effect of chemical information on population dynamics is rarely addressed. We designed a spatio-temporal parasitoid—host model to investigate the population dynamics when both the insect host and the parasitic

  14. From home range dynamics to population cycles: validation and realism of a common vole population model for pesticide risk assessment.

    Science.gov (United States)

    Wang, Magnus

    2013-04-01

    Despite various attempts to establish population models as standard tools in pesticide risk assessment, population models still receive limited acceptance by risk assessors and authorities in Europe. A main criticism of risk assessors is that population models are often not, or not sufficiently, validated. Hence the realism of population-level risk assessments conducted with such models remains uncertain. We therefore developed an individual-based population model for the common vole, Microtus arvalis, and demonstrate how population models can be validated in great detail based on published data. The model is developed for application in pesticide risk assessment, therefore, the validation covers all areas of the biology of the common vole that are relevant for the analysis of potential effects and recovery after application of pesticides. Our results indicate that reproduction, survival, age structure, spatial behavior, and population dynamics reproduced from the model are comparable to field observations. Also interannual population cycles, which are frequently observed in field studies of small mammals, emerge from the population model. These cycles were shown to be caused by the home range behavior and dispersal. As observed previously in the field, population cycles in the model were also stronger for longer breeding season length. Our results show how validation can help to evaluate the realism of population models, and we discuss the importance of taking field methodology and resulting bias into account. Our results also demonstrate how population models can help to test or understand biological mechanisms in population ecology.

  15. Dynamics of a physiologically structured population in a time-varying environment

    DEFF Research Database (Denmark)

    Heilmann, Irene Louise Torpe; Starke, Jens; Andersen, Ken Haste

    2016-01-01

    or less regularly. In order to understand the interaction between an external environmental forcing and the internal dynamics in a population, we examine the response of a physiologically structured population model to a periodic variation in the food resource. We explore the addition of forcing in two......Physiologically structured population models have become a valuable tool to model the dynamics of populations. In a stationary environment such models can exhibit equilibrium solutions as well as periodic solutions. However, for many organisms the environment is not stationary, but varies more...... cases: (A) where the population dynamics is in equilibrium in a stationary environment, and (B) where the population dynamics exhibits a periodic solution in a stationary environment. When forcing is applied in case A, the solutions are mainly periodic. In case B the forcing signal interacts...

  16. Dynamics of a combined Medea-underdominant population transformation system.

    Science.gov (United States)

    Gokhale, Chaitanya S; Reeves, Richard Guy; Reed, Floyd A

    2014-05-07

    Transgenic constructs intended to be stably established at high frequencies in wild populations have been demonstrated to "drive" from low frequencies in experimental insect populations. Linking such population transformation constructs to genes which render them unable to transmit pathogens could eventually be used to stop the spread of vector-borne diseases like malaria and dengue. Generally, population transformation constructs with only a single transgenic drive mechanism have been envisioned. Using a theoretical modelling approach we describe the predicted properties of a construct combining autosomal Medea and underdominant population transformation systems. We show that when combined they can exhibit synergistic properties which in broad circumstances surpass those of the single systems. With combined systems, intentional population transformation and its reversal can be achieved readily. Combined constructs also enhance the capacity to geographically restrict transgenic constructs to targeted populations. It is anticipated that these properties are likely to be of particular value in attracting regulatory approval and public acceptance of this novel technology.

  17. Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae) in dry and wet seasons

    OpenAIRE

    SUWARNO

    2010-01-01

    Suwarno (2010) Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae) in dry and wet seasons. Biodiversitas 11: 19-23. The population dynamic of Papilio polytes L. (Lepidoptera: Papilionidae) in dry and wet seasons was investigated in the citrus orchard in Tasek Gelugor, Pulau Pinang, Malaysia. Population of immature stages of P. polytes was observed alternate day from January to March 2006 (dry season, DS), from April to July 2006 (secondary wet season, ...

  18. A new ODE tumor growth modeling based on tumor population dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Oroji, Amin; Omar, Mohd bin [Institute of Mathematical Sciences, Faculty of Science University of Malaya, 50603 Kuala Lumpur, Malaysia amin.oroji@siswa.um.edu.my, mohd@um.edu.my (Malaysia); Yarahmadian, Shantia [Mathematics Department Mississippi State University, USA Syarahmadian@math.msstate.edu (United States)

    2015-10-22

    In this paper a new mathematical model for the population of tumor growth treated by radiation is proposed. The cells dynamics population in each state and the dynamics of whole tumor population are studied. Furthermore, a new definition of tumor lifespan is presented. Finally, the effects of two main parameters, treatment parameter (q), and repair mechanism parameter (r) on tumor lifespan are probed, and it is showed that the change in treatment parameter (q) highly affects the tumor lifespan.

  19. The coexistence of Baird's tapir (Tapirus bairdii) and indigenous hunters in northeastern Honduras.

    Science.gov (United States)

    Dunn, Marc; Estrada, Nereyda; Smith, Derek A

    2012-12-01

    The Baird's tapir (Tapirus bairdii) is a popular game species throughout Central America, particularly among indigenous populations, and is currently endangered. Research on Miskitu hunting was conducted over 4 months in a remote region in northeastern Honduras that overlaps with the Río Plátano Biosphere Reserve. The hunting zone was mapped together with hunters and interviews were conducted with elders and other community members about tapir hunting. Results show that tapir harvesting is targeted toward specific habitats at specific times of year. Harvest rates for one year suggest that tapir hunting in the area exceeds estimates of maximum sustainable production. Nevertheless, field surveys reveal the presence of tapir within 1 km of the community, and its harvest tends to be nearby, in both forested and agricultural landscapes, suggesting that the animal has not been depleted in the area. It appears that the existence of forest areas adjacent to the hunting zone that do not experience hunting, together with the anthropogenic habitats created through shifting cultivation, are factors that help explain the presence of tapirs in the area. The article concludes with a discussion regarding the potential positive role of indigenous hunters in tapir conservation throughout its distribution range.

  20. Community trust and household health: A spatially-based approach with evidence from rural Honduras.

    Science.gov (United States)

    Zarychta, Alan

    2015-12-01

    What is the relationship between community trust and household health? Scholars working to understand the effects of trust and social capital on human health tend to focus on individual characteristics or social environments, frequently without integrating these two dimensions. In light of this, the present paper makes contributions in both conceptualization and measurement. First, I develop a spatially-based approach for operationalizing community trust as the product of individual orientation and social environment. This approach highlights the need for a household to trust its neighbors and for those neighbors to reciprocate trust in order to constitute the psychological and material mechanisms critical for linking social context to individual health. Second, I illustrate the utility of this measure by evaluating the relationship between community trust and self-rated health status using an original population census survey from 2009 to 2010 for two municipalities in western Honduras (approximately 2800 households with a response rate of 94.9%). I implement spatial regression analysis and show that there is a positive and substantively meaningful relationship between community trust and household health; households that are trusting and surrounded by similarly trusting neighbors report better health status, while those in uncertain or mutually distrusting environments report worse health. The theory and results presented here suggest an important link between trust and social capital at the community level, which is particularly salient for rural regions in developing countries where health resources are scarce and community-based interventions are common.

  1. Identifying Ancient Settlement Patterns through LiDAR in the Mosquitia Region of Honduras

    Science.gov (United States)

    Fernández-Diaz, Juan Carlos; Cohen, Anna S.; Neil Cruz, Oscar; Gonzáles, Alicia M.; Leisz, Stephen J.; Pezzutti, Florencia; Shrestha, Ramesh; Carter, William

    2016-01-01

    The Mosquitia ecosystem of Honduras occupies the fulcrum between the American continents and as such constitutes a critical region for understanding past patterns of socio-political development and interaction. Heavy vegetation, rugged topography, and remoteness have limited scientific investigation. This paper presents prehistoric patterns of settlement and landuse for a critical valley within the Mosquitia derived from airborne LiDAR scanning and field investigation. We show that (i) though today the valley is a wilderness it was densely inhabited in the past; (ii) that this population was organized into a three-tiered system composed of 19 settlements dominated by a city; and, (iii) that this occupation was embedded within a human engineered landscape. We also add to a growing body of literature that demonstrates the utility of LiDAR as means for rapid cultural assessments in undocumented regions for analysis and conservation. Our ultimate hope is for our work to promote protections to safeguard the unique and critically endangered Mosquitia ecosystem and other similar areas in need of preservation. PMID:27560962

  2. Identifying Ancient Settlement Patterns through LiDAR in the Mosquitia Region of Honduras.

    Science.gov (United States)

    Fisher, Christopher T; Fernández-Diaz, Juan Carlos; Cohen, Anna S; Neil Cruz, Oscar; Gonzáles, Alicia M; Leisz, Stephen J; Pezzutti, Florencia; Shrestha, Ramesh; Carter, William

    2016-01-01

    The Mosquitia ecosystem of Honduras occupies the fulcrum between the American continents and as such constitutes a critical region for understanding past patterns of socio-political development and interaction. Heavy vegetation, rugged topography, and remoteness have limited scientific investigation. This paper presents prehistoric patterns of settlement and landuse for a critical valley within the Mosquitia derived from airborne LiDAR scanning and field investigation. We show that (i) though today the valley is a wilderness it was densely inhabited in the past; (ii) that this population was organized into a three-tiered system composed of 19 settlements dominated by a city; and, (iii) that this occupation was embedded within a human engineered landscape. We also add to a growing body of literature that demonstrates the utility of LiDAR as means for rapid cultural assessments in undocumented regions for analysis and conservation. Our ultimate hope is for our work to promote protections to safeguard the unique and critically endangered Mosquitia ecosystem and other similar areas in need of preservation.

  3. Data Driven Approach for High Resolution Population Distribution and Dynamics Models

    Energy Technology Data Exchange (ETDEWEB)

    Bhaduri, Budhendra L [ORNL; Bright, Eddie A [ORNL; Rose, Amy N [ORNL; Liu, Cheng [ORNL; Urban, Marie L [ORNL; Stewart, Robert N [ORNL

    2014-01-01

    High resolution population distribution data are vital for successfully addressing critical issues ranging from energy and socio-environmental research to public health to human security. Commonly available population data from Census is constrained both in space and time and does not capture population dynamics as functions of space and time. This imposes a significant limitation on the fidelity of event-based simulation models with sensitive space-time resolution. This paper describes ongoing development of high-resolution population distribution and dynamics models, at Oak Ridge National Laboratory, through spatial data integration and modeling with behavioral or activity-based mobility datasets for representing temporal dynamics of population. The model is resolved at 1 km resolution globally and describes the U.S. population for nighttime and daytime at 90m. Integration of such population data provides the opportunity to develop simulations and applications in critical infrastructure management from local to global scales.

  4. Dynamic of population-dynamics in a medically important snail species Lymnaea (Radix Luteola (Lamarck

    Directory of Open Access Journals (Sweden)

    T. K. Misra

    1993-09-01

    Full Text Available The life-cycle parameters of the snail Lymnaea (Radix luteola and the factors influencing the same have been studied under laboratory conditions. Ins each month, from July 1990 to June 1991, a batch of 100 zero-day old individual were considered for studies. The snails of April batch survived for 19.42 days while those in December batch survived for 87.45 days. The May batch individual though survived for 65.67 days gained maximum shell size (15.84 mm in length and body weight (419.87 mg. All individuals of April batch died prior to attainment of sexual maturity. In the remaining 11 batches the snails became sexually mature between 32 and 53 days. At this stage, they were with varying shell lengths, 9.3 mm to 13,11 mm in respect to batches. The reproduction period varied from 1-67 days. An individual laid, on an average, 0,25 (March batch to 443.67 (May batch eggs in its life-span. A batch of such snails would leave 24312, 22520, 720268, 80408, 76067, 418165, 214, 9202, 0, 0, 2459386 and 127894 individuals at the end of 352nd day. Since the environmental conditions were almost similar the 'dynamic' of population dynamics seems to be involved with the 'strain' of the snail individuals of the batches concerned.

  5. Smith, Malthus and Recent Evidence in Global Population Dynamics

    OpenAIRE

    Xiao Jiang; Luis Villanueva

    2015-01-01

    In conventional economic theories, population is determined outside of the economic system. However, classical political economists such as Adam Smith and Thomas Malthus have long argued for the endogenous determination of population, hence establishing a connection between economics and demography. Foley (2000) used empirically established global per capita output-fertility schedule based on the 1960-1992 Extended Penn World Tables to project the population stabilizing level of world per cap...

  6. Intraspecific Competition and Population Dynamics of Aedes aegypti

    Science.gov (United States)

    Paixão, C. A.; Charret, I. C.; Lima, R. R.

    2012-04-01

    We report computational simulations for the evolution of the population of the dengue vector, Aedes aegypti mosquitoes. The results suggest that controlling the mosquito population, on the basis of intraspecific competition at the larval stage, can be an efficient mechanism for controlling the spread of the epidemic. The results also show the presence of a kind of genetic evolution in vector population, which results mainly in increasing the average lifespan of individuals in adulthood.

  7. Population dynamics of some coccids (Coccoidea: Hemiptera) infesting sandal (Santalum album) in Bangalore, India

    Institute of Scientific and Technical Information of China (English)

    Ramachandran Sundararaj; Raja Muthukrishnan

    2011-01-01

    A study was conducted to investigate the population dynamics of four important coccids viz., Aonidiella orientalis (Newstead), Ceroplastes actiniformis Green, Cardiococcus bivalvata (Green) and Parasaissetia nigra (Nietner) infesting sandal in Bangalore, India. Meteorological data viz., monthly mean maximum and minimum temperatures,morning and evening relative humidity and total rainfall were also collected during the experimental period for statistical analysis to ascertain their influence on the population of ceccids. The results show that all the four coccids are infesting sandal throughout the year. Maximum temperature exhibited significantly negative correlation with the population dynamics of A.orientalis, while other weather parameters did not show much influence on its incidence. In case of C. bivalvata, minimum temperature and morning relative humidity exhibited significant positive correlation with its population dynamics while other weather parameters had less significant effect on its population dynamics. For C.actiniformis and P. nigra, none of the weather factors seem to have influence on their incidences.

  8. Access to sterilization in two hospitals in Honduras.

    Science.gov (United States)

    Janowitz, B; Núñez, J

    1981-01-01

    The availability of postpartum sterilizations for women with obstetric deliveries at 2 hospitals in Honduras -- the Hospital Materno-Infantil in Teguicgalpa and the Hospital Leonardo Martinez in San Pedro -- was examined. Data were collected from the hospitals using a maternity record form that provided information regarding patients' sociodemographic backgrounds, obstetric histories, and contraceptive practices. The patients were asked about thier use of contraceptives before pregnancy and about their possible plans for contraception after delivery. If the patient was sterilized before leaving the hospital, this information was also recorded on the form. Analysis of the data reveals that the hospitals do not encourage women to be sterilized, and that they do a poor job of providing services for those women interested in sterilization. Of 18,523 women giving birth from 1977 through 1979, a total of 13,241 (71.5%) indicated that they did not want any more children. Thus, these women constituted a group for which female sterilization could be the contraceptive method of choice. Of these, 13,241 women, 3063 said that they planned to be sterilized. Among women having abortions at these hospitals, about 1/2 do not return for a followup visit 4-6 weeks later. To be eligible for sterilization in Honduras, a woman is supposed to satisfy the "rule of 80" (living children times age must equal 80). Only 6.8% of the women who planned to be but were not sterilized did not satisfy this rule. Among the women who were sterilized, the percentage of those who had cesarean deliveries was 69%. Of the women who said they planned to be sterilized but were not sterilized at delivery, less than 1% had cesarean sections. It seems apparent that women who have abdominal deliveries find it easier to obtain a sterilization at the time of delivery than do women with vaginal deliveries. At both hospitals, the proportion of sterilized women who did not satisfy the "rule of 80" was higher among

  9. Chaos and order in stateless societies: Intercommunity exchange as a factor impacting the population dynamical patterns

    Energy Technology Data Exchange (ETDEWEB)

    Medvinsky, Alexander B., E-mail: medvinsky@iteb.ru [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino 142290, Moscow Region (Russian Federation); Rusakov, Alexey V. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino 142290, Moscow Region (Russian Federation)

    2011-06-15

    Highlights: > We model community dynamics in stateless societies. > Intercommunity barter is shown to be a factor impacting the societies dynamics. > Increase in the human population growth rate can lead to appearance of chaos. > Secular and millennial cycles are found to arise as a result of the barter. - Abstract: The once abstract notions of dynamical chaos now appear naturally in various systems [Kaplan D, Glass L. Understanding nonlinear dynamics. New York: Springer; 1995]. As a result, future trajectories of the systems may be difficult to predict. In this paper, we demonstrate the appearance of chaotic dynamics in model human communities, which consist of producers of agricultural product and producers of agricultural equipment. In the case of a solitary community, the horizon of predictability of the human population dynamics is shown to be dependent on both intrinsic instability of the dynamics and the chaotic attractor sizes. Since a separate community is usually a part of a larger commonality, we study the dynamics of social systems consisting of two interacting communities. We show that intercommunity barter can lead to stabilization of the dynamics in one of the communities, which implies persistence of stable equilibrium under changes of the maximum value of the human population growth rate. However, in the neighboring community, the equilibrium turns into a stable limit cycle as the maximum value of the human population growth rate increases. Following an increase in the maximum value of the human population growth rate leads to period-doubling bifurcations resulting in chaotic dynamics. The horizon of predictability of the chaotic oscillations is found to be limited by 5 years. We demonstrate that the intercommunity interaction can lead to the appearance of long-period harmonics in the chaotic time series. The period of the harmonics is of order 100 and 1000 years. Hence the long-period changes in the population size may be considered as an

  10. Utilization of Computer Technology in the Third World: An Evaluation of Computer Operations at the University of Honduras.

    Science.gov (United States)

    Shermis, Mark D.

    This report of the results of an evaluation of computer operations at the University of Honduras (Universidad Nacional Autonoma de Honduras) begins by discussing the problem--i.e., poor utilization of the campus mainframe computer--and listing the hardware and software available in the computer center. Data collection methods are summarized,…

  11. Note on the Honduras Radio Schools (ACPH--Accion Cultural Popular Hondureno). IEC Discussion Paper. Appendix 4.

    Science.gov (United States)

    Young, Michael

    This report on the radio schools in Honduras, Central America, includes (1) an account of an afternoon session of the radio school's Primary Equivalence Programme (PEPA), including a testimonial of a student and a statement regarding the importance of the monitors; (2) information on the social background of Honduras; (3) an historical account of…

  12. A new species in the genus Amphipteryx Selys, 1853 (Odonata, Amphipterygidae) from Pico Bonito National Park, Honduras.

    Science.gov (United States)

    Jocque, Merlijn; Argueta, Ivany

    2014-01-01

    The Mesoamerican damselfly genus Amphipteryx includes four species: Amphipteryx agrioides (Mexico), A. chiapensis (Mexico), A. meridionalis (Honduras) and A. nataliae (Verapaz, Guatemala). We describe a fifth species, Amphipteryx jaroli, from the cloud forest in Pico Bonito National park, Honduras. Additionally we include an up to date key of all species in the genus for both sexes.

  13. A new species in the genus Amphipteryx Selys, 1853 (Odonata, Amphipterygidae from Pico Bonito National Park, Honduras

    Directory of Open Access Journals (Sweden)

    Merlijn Jocque

    2014-05-01

    Full Text Available The Mesoamerican damselfly genus Amphipteryx includes four species: Amphipteryx agrioides (Mexico, A.chiapensis (Mexico, A. meridionalis (Honduras and A. nataliae (Verapaz, Guatemala. We describe a fifth species, Amphipteryx jaroli, from the cloud forest in Pico Bonito National park, Honduras. Additionally we include an up to date key of all species in the genus for both sexes.

  14. Note on the Honduras Radio Schools (ACPH--Accion Cultural Popular Hondureno). IEC Discussion Paper. Appendix 4.

    Science.gov (United States)

    Young, Michael

    This report on the radio schools in Honduras, Central America, includes (1) an account of an afternoon session of the radio school's Primary Equivalence Programme (PEPA), including a testimonial of a student and a statement regarding the importance of the monitors; (2) information on the social background of Honduras; (3) an historical account of…

  15. A mechanistic analysis of density dependence in algal population dynamics

    Directory of Open Access Journals (Sweden)

    Adrian eBorlestean

    2015-04-01

    Full Text Available Population density regulation is a fundamental principle in ecology, but the specific process underlying functional expression of density dependence remains to be fully elucidated. One view contends that patterns of density dependence are largely fixed across a species irrespective of environmental conditions, whereas another is that the strength and expression of density dependence are fundamentally variable depending on the nature of exogenous or endogenous constraints acting on the population. We conducted a study investigating the expression of density dependence in Chlamydomonas spp. grown under a gradient from low to high nutrient density. We predicted that the relationship between per capita growth rate (pgr and population density would vary from concave up to concave down as nutrient density became less limiting and populations experienced weaker density regulation. Contrary to prediction, we found that the relationship between pgr and density became increasingly concave-up as nutrient levels increased. We also found that variation in pgr increased, and pgr levels reached higher maxima in nutrient-limited environments. Most likely, these results are attributable to population growth suppression in environments with high intraspecific competition due to limited nutrient resources. Our results suggest that density regulation is strongly variable depending on exogenous and endogenous processes acting on the population, implying that expression of density dependence depends extensively on local conditions. Additional experimental work should reveal the mechanisms influencing how the expression of density dependence varies across populations through space and time.

  16. Confidence interval for number of population in dynamical stochastic exponential population growth models

    Directory of Open Access Journals (Sweden)

    Morteza Khodabin

    2013-06-01

    Full Text Available In this paper, the confidence interval for the solution of stochastic exponential population growth model where the so-called parameter, population growth rate is not completely definite and it depends on some random environmental effects is obtained. We use Iran population data in the period 1921-2006 as an example.

  17. Suppression of Beneficial Mutations in Dynamic Microbial Populations

    Science.gov (United States)

    Bittihn, Philip; Hasty, Jeff; Tsimring, Lev S.

    2017-01-01

    Quantitative predictions for the spread of mutations in bacterial populations are essential to interpret evolution experiments and to improve the stability of synthetic gene circuits. We derive analytical expressions for the suppression factor for beneficial mutations in populations that undergo periodic dilutions, covering arbitrary population sizes, dilution factors, and growth advantages in a single stochastic model. We find that the suppression factor grows with the dilution factor and depends nontrivially on the growth advantage, resulting in the preferential elimination of mutations with certain growth advantages. We confirm our results by extensive numerical simulations.

  18. The demographic drivers of local population dynamics in two rare migratory birds.

    Science.gov (United States)

    Schaub, Michael; Reichlin, Thomas S; Abadi, Fitsum; Kéry, Marc; Jenni, Lukas; Arlettaz, Raphaël

    2012-01-01

    The exchange of individuals among populations can have strong effects on the dynamics and persistence of a given population. Yet, estimation of immigration rates remains one of the greatest challenges for animal demographers. Little empirical knowledge exists about the effects of immigration on population dynamics. New integrated population models fitted using Bayesian methods enable simultaneous estimation of fecundity, survival and immigration, as well as the growth rate of a population of interest. We applied this novel analytical framework to the demography of two populations of long-distance migratory birds, hoopoe Upupa epops and wryneck Jynx torquilla, in a study area in south-western Switzerland. During 2002-2010, the hoopoe population increased annually by 11%, while the wryneck population remained fairly stable. Apparent juvenile and adult survival probability was nearly identical in both species, but fecundity and immigration were slightly higher in the hoopoe. Hoopoe population growth rate was strongly correlated with juvenile survival, fecundity and immigration, while that of wrynecks strongly correlated only with immigration. This indicates that demographic components impacting the arrival of new individuals into the populations were more important for their dynamics than demographic components affecting the loss of individuals. The finding that immigration plays a crucial role in the population growth rates of these two rare species emphasizes the need for a broad rather than local perspective for population studies, and the development of wide-scale conservation actions.

  19. POPULATION DYNAMICS OF SMALL MAMMALS ACROSS A NITROGEN AMENDED LANDSCAPE

    Science.gov (United States)

    Biogeochemical alterations of the nitrogen cycle from anthropogenic activities could have significant effects on ecological processes at the population, community and ecosystem levels. Nitrogen additions in grasslands have produced qualitative and quantitative changes in vegetat...

  20. Population dynamics of aquatic snails in Pampulha reservoir

    Directory of Open Access Journals (Sweden)

    J. R. Freitas

    1987-01-01

    Full Text Available An attempt was made to determine more accurately the density of molluskan populations in the Pampulha reservoir, using the quadrate method, intending to detect the fluctuation of the populations density, the habitat conditions and the possible competitive interactions among Biomphalaria tenagophila, Melanoides tuberculata, Pomacea haustrum and Biomphalaria glabrata, through the analysis of populational parameters. Among the most significative facts observed in the reservoir it has to be mentioned: the almost disappearance of B. glabrata; the invasion, colonization, fixation and fast growing of M. tuberculata population until reaching about 11,000 individuals/[square metre]; the density fluctuations of B. tenagophila, P. haustrum and M. tuberculata alives and deads; differences on the habitat preference of these three molluskan species at the edge (at the limit earth-water, at 0.70m and 1.40m from the shore line; monthly mortality rates and reproduction seasons of the species.

  1. Development and validation of an individual based Daphnia magna population model: The influence of crowding on population dynamics

    NARCIS (Netherlands)

    Preuss, T.G.; Hammers-Wirtz, M.; Hommen, U.; Rubach, M.N.; Ratte, H.T.

    2009-01-01

    An individual-based model was developed to predict the population dynamics of Daphnia magna at laboratory conditions from individual life-history traits observed in experiments with different feeding conditions. Within the model, each daphnid passes its individual life cycle including feeding on alg

  2. Growth dynamics and the evolution of cooperation in microbial populations

    OpenAIRE

    Jonas Cremer; Anna Melbinger; Erwin Frey

    2012-01-01

    Microbes providing public goods are widespread in nature despite running the risk of being exploited by free-riders. However, the precise ecological factors supporting cooperation are still puzzling. Following recent experiments, we consider the role of population growth and the repetitive fragmentation of populations into new colonies mimicking simple microbial life-cycles. Individual-based modeling reveals that demographic fluctuations, which lead to a large variance in the composition of c...

  3. Causes and consequences of complex population dynamics in an annual plant, Cardamine pensylvanica

    Energy Technology Data Exchange (ETDEWEB)

    Crone, E.E.

    1995-11-08

    The relative importance of density-dependent and density-independent factors in determining the population dynamics of plants has been widely debated with little resolution. In this thesis, the author explores the effects of density-dependent population regulation on population dynamics in Cardamine pensylvanica, an annual plant. In the first chapter, she shows that experimental populations of C. pensylvanica cycled from high to low density in controlled constant-environment conditions. These cycles could not be explained by external environmental changes or simple models of direct density dependence (N{sub t+1} = f[N{sub t}]), but they could be explained by delayed density dependence (N{sub t+1} = f[N{sub t}, N{sub t+1}]). In the second chapter, she shows that the difference in the stability properties of population growth models with and without delayed density dependence is due to the presence of Hopf as well as slip bifurcations from stable to chaotic population dynamics. She also measures delayed density dependence due to effects of parental density on offspring quality in C. pensylvanica and shows that this is large enough to be the cause of the population dynamics observed in C. pensylvanica. In the third chapter, the author extends her analyses of density-dependent population growth models to include interactions between competing species. In the final chapter, she compares the effects of fixed spatial environmental variation and variation in population size on the evolutionary response of C. pensylvanica populations.

  4. Dynamical Mueller's Ratchet: Population Size Dependence of Evolutionary Paths in Bacteria

    Science.gov (United States)

    Lorenz, Dirk; Park, Jeong-Man; Deem, Michael; Michael Deem Team

    2011-03-01

    Experimental evolution has recently enabled the complete quantitative description of small-dimensional fitness landscapes. Quasispecies theory allows the mathematical modeling of evolution on such a landscape. Typically, analytic solutions for these models are only exactly solvable for the case of an infinite population. Here we use a functional integral representation of population dynamics and solve it using the Schwinger Boson method. This allows us to compute the first-order correction to the average fitness for finite populations. We will use these results to explain the experimental observations of dynamics of evolution in finite populations.

  5. Nutritional quality of foods marketed to children in Honduras.

    Science.gov (United States)

    Gunderson, Matthew D; Clements, Dennis; Benjamin Neelon, Sara E

    2014-02-01

    Evidence suggests that exposure to advertising of unhealthy foods may contribute to increased rates of obesity in children. This study examined the extent to which television stations marketed unhealthy foods to children during after-school programming aired over one week in La Ceiba, Honduras. Content analysis was performed on four television stations, including one broadcast station and three cable networks. Eighty hours of programming were recorded and analyzed. Advertised products were categorized as food or non-food items, with food items further classified as healthy or unhealthy. Advertisements were coded as those aimed at children, adults, or both, and chi-square tests were used to compare the proportion of unhealthy advertisements by target audience. A total of 2271 advertisements aired during the observation period, with 1120 marketing products (49.3%). Of those, 397 (35.4%) promoted foods-30.2% were for healthy foods and 69.8% for unhealthy foods. The unhealthy foods were all advertised on cable networks and not the broadcast station. Children appeared to be targeted more than adults in advertisements for unhealthy foods (92.1%, p<0.001). Cable television programming during after-school hours advertised primarily unhealthy foods. Exposure to these advertisements may promote consumption of unhealthy foods by children, increasing their risk of obesity.

  6. Postpartum hemorrhage prevention: a case study in northern rural Honduras.

    Science.gov (United States)

    Low, Lisa Kane; Bailey, Joanne Motiño; Sacks, Emma; Medina, Lilian; Piñeda, Hector Oqueli Lopez

    2008-01-01

    Postpartum hemorrhage (PPH) is the leading cause of maternal mortality globally. Safe Motherhood policies have been directed towards the reduction of PPH by recommending active management of third-stage labor as the standard of care. One component of active management involves routine use of a uterotonic agent within 1 minute of the delivery of the baby. A case study at Clínica Materno-Infantil, a free-standing public birth center in Honduras, is presented, focusing on methods to reduce PPH. The nursing staff was trained to estimate blood loss and in methods to manage PPH, including elements of active management of the third stage of labor. Medical records were reviewed and an analysis of PPH management compared to estimated blood loss (EBL) was conducted. There was no significant correlation between PPH management techniques and EBL (r = .060; P = .368). There was a statistically significant (P Materno-Infantil, routine use of a uterotonic agent appears beneficial and further implementation of active management of the third stage of labor appears warranted.

  7. A Study on Maize Farmers in Occidental Honduras

    Directory of Open Access Journals (Sweden)

    Ruerd Ruben

    2005-01-01

    Full Text Available El crédito ha sido considerado comúnmente como una estrategia importante para influir en el manejo de recursos y las estrategias de sobrevivencia campesina. Los productores con mejor acceso a recursos financieros tienen más opciones para incrementar el retorno marginal de factores variables de producción, tales como trabajo y fertilizantes. Es probable que la sustitución de factores se lleva a cabo hacia sistemas de producción más intensivos que puedan garantizar mejor la seguridad alimentaría y favorecer el uso sostenible de los suelos. Hemos realizado un estudio entre productores de maíz ubicados en el departamento occidental de Lempira en Honduras para analizar el impacto del uso de crédito sobre el retorno marginal de tierra, trabajo y fertilizantes. Encontramos que las proporciones atribuidas a trabajo y fertilizantes aumentaron considerablemente para campesinos que utilizan crédito, mientras que la proporción del factor tierra se redujo fuertemente. La posición relativa de terratenientes tiende a deteriorarse, pero la influencia de suministradores de insumos puede incrementar. Dadas las complementaridades entre fertilizantes y trabajo, el crédito puede ser un importante instrumento para cambiar las relaciones de clase en el campo.

  8. Population dynamics and angler exploitation of the unique muskellunge population in Shoepack Lake, Voyageurs National Park, Minnesota

    Science.gov (United States)

    Frohnauer, N.K.; Pierce, C.L.; Kallemeyn, L.W.

    2007-01-01

    A unique population of muskellunge Esox masquinongy inhabits Shoepack Lake in Voyageurs National Park, Minnesota. Little is known about its status, dynamics, and angler exploitation, and there is concern for the long-term viability of this population. We used intensive sampling and mark-recapture methods to quantify abundance, survival, growth, condition, age at maturity and fecundity and angler surveys to quantify angler pressure, catch rates, and exploitation. During our study, heavy rain washed out a dam constructed by beavers Castor canadensis which regulates the water level at the lake outlet, resulting in a nearly 50% reduction in surface area. We estimated a population size of 1,120 adult fish at the beginning of the study. No immediate reduction in population size was detected in response to the loss of lake area, although there was a gradual, but significant, decline in population size over the 2-year study. Adults grew less than 50 mm per year, and relative weight (W r) averaged roughly 80. Anglers were successful in catching, on average, two fish during a full day of angling, but harvest was negligible. Shoepack Lake muskellunge exhibit much slower growth rates and lower condition, but much higher densities and angler catch per unit effort (CPUE), than other muskellunge populations. The unique nature, limited distribution, and location of this population in a national park require special consideration for management. The results of this study provide the basis for assessing the long-term viability of the Shoepack Lake muskellunge population through simulations of long-term population dynamics and genetically effective population size. ?? Copyright by the American Fisheries Society 2007.

  9. Spatial and temporal dynamics of fucoid populations (Ascophyllum nodosum and Fucus serratus: a comparison between central and range edge populations.

    Directory of Open Access Journals (Sweden)

    Rita M Araújo

    Full Text Available Persistence of populations at range edges relies on local population dynamics and fitness, in the case of geographically isolated populations of species with low dispersal potential. Focusing on spatial variations in demography helps to predict the long-term capability for persistence of populations across the geographical range of species' distribution. The demography of two ecological and phylogenetically close macroalgal species with different life history characteristics was investigated by using stochastic, stage-based matrix models. Populations of Ascophyllum nodosum and Fucus serratus were sampled for up to 4 years at central locations in France and at their southern range limits in Portugal. The stochastic population growth rate (λ(s of A. nodosum was lower and more variable in central than in southern sites whilst for F. serratus this trend was reversed with λ(s much lower and more variable in southern than in central populations. Individuals were larger in central than in southern populations for both species, which was reflected in the lower transition probabilities of individuals to larger size classes and higher probability of shrinkage in the southern populations. In both central and southern populations elasticity analysis (proportional sensitivity of population growth rate showed that fertility elements had a small contribution to λ(s that was more sensitive to changes in matrix transitions corresponding to survival. The highest elasticities were found for loop transitions in A. nodosum and for growth to larger size classes in F. serratus. Sensitivity analysis showed high selective pressure on individual growth for both species at both locations. The results of this study highlight the deterministic role of species-specific life-history traits in population demography across the geographical range of species. Additionally, this study demonstrates that individuals' life-transitions differ in vulnerability to environmental

  10. Population dynamics of a natural red deer population over 200 years detected via substantial changes of genetic variation.

    Science.gov (United States)

    Hoffmann, Gunther Sebastian; Johannesen, Jes; Griebeler, Eva Maria

    2016-05-01

    Most large mammals have constantly been exposed to anthropogenic influence over decades or even centuries. Because of their long generation times and lack of sampling material, inferences of past population genetic dynamics, including anthropogenic impacts, have only relied on the analysis of the structure of extant populations. Here, we investigate for the first time the change in the genetic constitution of a natural red deer population over two centuries, using up to 200-year-old antlers (30 generations) stored in trophy collections. To the best of our knowledge, this is the oldest DNA source ever used for microsatellite population genetic analyses. We demonstrate that government policy and hunting laws may have strong impacts on populations that can lead to unexpectedly rapid changes in the genetic constitution of a large mammal population. A high ancestral individual polymorphism seen in an outbreeding population (1813-1861) was strongly reduced in descendants (1923-1940) during the mid-19th and early 20th century by genetic bottlenecks. Today (2011), individual polymorphism and variance among individuals is increasing in a constant-sized (managed) population. Differentiation was high among periods (F ST > ***); consequently, assignment tests assigned individuals to their own period with >85% probability. In contrast to the high variance observed at nuclear microsatellite loci, mtDNA (D-loop) was monomorphic through time, suggesting that male immigration dominates the genetic evolution in this population.

  11. State aggregation and population dynamics in linear systems.

    Science.gov (United States)

    Rowe, Jonathan E; Vose, Michael D; Wright, Alden H

    2005-01-01

    We consider complex systems that are composed of many interacting elements, evolving under some dynamics. We are interested in characterizing the ways in which these elements may be grouped into higher-level, macroscopic states in a way that is compatible with those dynamics. Such groupings may then be thought of as naturally emergent properties of the system. We formalize this idea and, in the case that the dynamics are linear, prove necessary and sufficient conditions for this to happen. In cases where there is an underlying symmetry among the components of the system, group theory may be used to provide a strong sufficient condition. These observations are illustrated with some artificial life examples.

  12. Modelling population dynamics model formulation, fitting and assessment using state-space methods

    CERN Document Server

    Newman, K B; Morgan, B J T; King, R; Borchers, D L; Cole, D J; Besbeas, P; Gimenez, O; Thomas, L

    2014-01-01

    This book gives a unifying framework for estimating the abundance of open populations: populations subject to births, deaths and movement, given imperfect measurements or samples of the populations.  The focus is primarily on populations of vertebrates for which dynamics are typically modelled within the framework of an annual cycle, and for which stochastic variability in the demographic processes is usually modest. Discrete-time models are developed in which animals can be assigned to discrete states such as age class, gender, maturity,  population (within a metapopulation), or species (for multi-species models). The book goes well beyond estimation of abundance, allowing inference on underlying population processes such as birth or recruitment, survival and movement. This requires the formulation and fitting of population dynamics models.  The resulting fitted models yield both estimates of abundance and estimates of parameters characterizing the underlying processes.  

  13. Pacific Coast Caspian Terns: Dynamics of an expanding population

    Science.gov (United States)

    Gill, Robert E.; Mewaldt, L. Richard

    1983-01-01

    Nesting distribution, age-related seasonal movements, survivorship, and mechanisms of population expansion in Pacific Coast Caspian Terns (Sterna caspia) were examined primarily through analysis of 412 recoveries of birds banded as juveniles between 1935 and 1980. Since the beginning of this century, the population has shifted from nesting in numerous small colonies associated with freshwater marshes in interior California and southern Oregon to nesting primarily in large colonies on human-created habitats along the coast. Colonies at Grays Harbor, Washington and San Francisco and San Diego bays, California account for 77% of the current Pacific Coast population (6,000 pairs), which has breeding and wintering areas separate from those of populations east of the continental divide. There also appears to be some segregation on the wintering grounds by birds from the three major colonies within the Pacific population. Age-related seasonal movements in the Pacific population are characterized by (1) a brief period of northward dispersal by newly fledged birds before migrating to the wintering grounds, (2) a residency on the wintering grounds through their second winter, (3) a return to the breeding grounds the third summer, when most birds are thought to prospect breeding sites and some may breed, and (4) attainment of adulthood the fourth summer, with subsequent annual movements between wintering and breeding grounds.The Pacific population has increased 70% since 1960, apparently all by intrinsic growth. Over half (57%) of the fledglings reach their fourth year, and they have a subsequent annual survival rate of 89% and a mean breeding life expectancy of 8.6 yr. An average annual fledging rate of 0.64 young per pair was calculated as necessary to have provided the observed growth of the population during its recent expansion. Growth of some of the individual colonies, however, particularly those in Washington, could only have resulted from extensive recruitment of

  14. Efficacy of chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in Honduras.

    Science.gov (United States)

    Mejia Torres, Rosa Elena; Banegas, Engels Ilich; Mendoza, Meisy; Diaz, Cesar; Bucheli, Sandra Tamara Mancero; Fontecha, Gustavo A; Alam, Md Tauqeer; Goldman, Ira; Udhayakumar, Venkatachalam; Zambrano, Jose Orlinder Nicolas

    2013-05-01

    Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization-World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras.

  15. Midcontinental Native American population dynamics and late Holocene hydroclimate extremes

    Science.gov (United States)

    Bird, Broxton W.; Wilson, Jeremy J.; Gilhooly, William P., III; Steinman, Byron A.; Stamps, Lucas

    2017-01-01

    Climate’s influence on late Pre-Columbian (pre-1492 CE), maize-dependent Native American populations in the midcontinental United States (US) is poorly understood as regional paleoclimate records are sparse and/or provide conflicting perspectives. Here, we reconstruct regional changes in precipitation source and seasonality and local changes in warm-season duration and rainstorm events related to the Pacific North American pattern (PNA) using a 2100-year-long multi-proxy lake-sediment record from the midcontinental US. Wet midcontinental climate reflecting negative PNA-like conditions occurred during the Medieval Climate Anomaly (950–1250 CE) as Native American populations adopted intensive maize agriculture, facilitating population aggregation and the development of urban centers between 1000–1200 CE. Intensifying midcontinental socio-political instability and warfare between 1250–1350 CE corresponded with drier positive PNA-like conditions, culminating in the staggered abandonment of many major Native American river valley settlements and large urban centers between 1350–1450 CE during an especially severe warm-season drought. We hypothesize that this sustained drought interval rendered it difficult to support dense populations and large urban centers in the midcontinental US by destabilizing regional agricultural systems, thereby contributing to the host of socio-political factors that led to population reorganization and migration in the midcontinent and neighboring regions shortly before European contact.

  16. Midcontinental Native American population dynamics and late Holocene hydroclimate extremes

    Science.gov (United States)

    Bird, Broxton W.; Wilson, Jeremy J.; Gilhooly III, William P.; Steinman, Byron A.; Stamps, Lucas

    2017-01-01

    Climate’s influence on late Pre-Columbian (pre-1492 CE), maize-dependent Native American populations in the midcontinental United States (US) is poorly understood as regional paleoclimate records are sparse and/or provide conflicting perspectives. Here, we reconstruct regional changes in precipitation source and seasonality and local changes in warm-season duration and rainstorm events related to the Pacific North American pattern (PNA) using a 2100-year-long multi-proxy lake-sediment record from the midcontinental US. Wet midcontinental climate reflecting negative PNA-like conditions occurred during the Medieval Climate Anomaly (950–1250 CE) as Native American populations adopted intensive maize agriculture, facilitating population aggregation and the development of urban centers between 1000–1200 CE. Intensifying midcontinental socio-political instability and warfare between 1250–1350 CE corresponded with drier positive PNA-like conditions, culminating in the staggered abandonment of many major Native American river valley settlements and large urban centers between 1350–1450 CE during an especially severe warm-season drought. We hypothesize that this sustained drought interval rendered it difficult to support dense populations and large urban centers in the midcontinental US by destabilizing regional agricultural systems, thereby contributing to the host of socio-political factors that led to population reorganization and migration in the midcontinent and neighboring regions shortly before European contact. PMID:28139698

  17. Evolutionary game dynamics in populations with heterogenous structures.

    Directory of Open Access Journals (Sweden)

    Wes Maciejewski

    2014-04-01

    Full Text Available Evolutionary graph theory is a well established framework for modelling the evolution of social behaviours in structured populations. An emerging consensus in this field is that graphs that exhibit heterogeneity in the number of connections between individuals are more conducive to the spread of cooperative behaviours. In this article we show that such a conclusion largely depends on the individual-level interactions that take place. In particular, averaging payoffs garnered through game interactions rather than accumulating the payoffs can altogether remove the cooperative advantage of heterogeneous graphs while such a difference does not affect the outcome on homogeneous structures. In addition, the rate at which game interactions occur can alter the evolutionary outcome. Less interactions allow heterogeneous graphs to support more cooperation than homogeneous graphs, while higher rates of interactions make homogeneous and heterogeneous graphs virtually indistinguishable in their ability to support cooperation. Most importantly, we show that common measures of evolutionary advantage used in homogeneous populations, such as a comparison of the fixation probability of a rare mutant to that of the resident type, are no longer valid in heterogeneous populations. Heterogeneity causes a bias in where mutations occur in the population which affects the mutant's fixation probability. We derive the appropriate measures for heterogeneous populations that account for this bias.

  18. Evolutionary game dynamics in populations with heterogenous structures.

    Science.gov (United States)

    Maciejewski, Wes; Fu, Feng; Hauert, Christoph

    2014-04-01

    Evolutionary graph theory is a well established framework for modelling the evolution of social behaviours in structured populations. An emerging consensus in this field is that graphs that exhibit heterogeneity in the number of connections between individuals are more conducive to the spread of cooperative behaviours. In this article we show that such a conclusion largely depends on the individual-level interactions that take place. In particular, averaging payoffs garnered through game interactions rather than accumulating the payoffs can altogether remove the cooperative advantage of heterogeneous graphs while such a difference does not affect the outcome on homogeneous structures. In addition, the rate at which game interactions occur can alter the evolutionary outcome. Less interactions allow heterogeneous graphs to support more cooperation than homogeneous graphs, while higher rates of interactions make homogeneous and heterogeneous graphs virtually indistinguishable in their ability to support cooperation. Most importantly, we show that common measures of evolutionary advantage used in homogeneous populations, such as a comparison of the fixation probability of a rare mutant to that of the resident type, are no longer valid in heterogeneous populations. Heterogeneity causes a bias in where mutations occur in the population which affects the mutant's fixation probability. We derive the appropriate measures for heterogeneous populations that account for this bias.

  19. Determinants of Health Service Responsiveness in Community-Based Vector Surveillance for Chagas Disease in Guatemala, El Salvador, and Honduras.

    Directory of Open Access Journals (Sweden)

    Ken Hashimoto

    Full Text Available Central American countries face a major challenge in the control of Triatoma dimidiata, a widespread vector of Chagas disease that cannot be eliminated. The key to maintaining the risk of transmission of Trypanosoma cruzi at lowest levels is to sustain surveillance throughout endemic areas. Guatemala, El Salvador, and Honduras integrated community-based vector surveillance into local health systems. Community participation was effective in detection of the vector, but some health services had difficulty sustaining their response to reports of vectors from the population. To date, no research has investigated how best to maintain and reinforce health service responsiveness, especially in resource-limited settings.We reviewed surveillance and response records of 12 health centers in Guatemala, El Salvador, and Honduras from 2008 to 2012 and analyzed the data in relation to the volume of reports of vector infestation, local geography, demography, human resources, managerial approach, and results of interviews with health workers. Health service responsiveness was defined as the percentage of households that reported vector infestation for which the local health service provided indoor residual spraying of insecticide or educational advice. Eight potential determinants of responsiveness were evaluated by linear and mixed-effects multi-linear regression. Health service responsiveness (overall 77.4% was significantly associated with quarterly monitoring by departmental health offices. Other potential determinants of responsiveness were not found to be significant, partly because of short- and long-term strategies, such as temporary adjustments in manpower and redistribution of tasks among local participants in the effort.Consistent monitoring within the local health system contributes to sustainability of health service responsiveness in community-based vector surveillance of Chagas disease. Even with limited resources, countries can improve health

  20. Determinants of Health Service Responsiveness in Community-Based Vector Surveillance for Chagas Disease in Guatemala, El Salvador, and Honduras.

    Science.gov (United States)

    Hashimoto, Ken; Zúniga, Concepción; Romero, Eduardo; Morales, Zoraida; Maguire, James H

    2015-01-01

    Central American countries face a major challenge in the control of Triatoma dimidiata, a widespread vector of Chagas disease that cannot be eliminated. The key to maintaining the risk of transmission of Trypanosoma cruzi at lowest levels is to sustain surveillance throughout endemic areas. Guatemala, El Salvador, and Honduras integrated community-based vector surveillance into local health systems. Community participation was effective in detection of the vector, but some health services had difficulty sustaining their response to reports of vectors from the population. To date, no research has investigated how best to maintain and reinforce health service responsiveness, especially in resource-limited settings. We reviewed surveillance and response records of 12 health centers in Guatemala, El Salvador, and Honduras from 2008 to 2012 and analyzed the data in relation to the volume of reports of vector infestation, local geography, demography, human resources, managerial approach, and results of interviews with health workers. Health service responsiveness was defined as the percentage of households that reported vector infestation for which the local health service provided indoor residual spraying of insecticide or educational advice. Eight potential determinants of responsiveness were evaluated by linear and mixed-effects multi-linear regression. Health service responsiveness (overall 77.4%) was significantly associated with quarterly monitoring by departmental health offices. Other potential determinants of responsiveness were not found to be significant, partly because of short- and long-term strategies, such as temporary adjustments in manpower and redistribution of tasks among local participants in the effort. Consistent monitoring within the local health system contributes to sustainability of health service responsiveness in community-based vector surveillance of Chagas disease. Even with limited resources, countries can improve health service

  1. Development of a Dynamic Population Balance Plant Simulator for Mineral Processing Circuits

    National Research Council Canada - National Science Library

    Fatemeh Khoshnam; Mohammad reza Khalesi; Ahmad Khodadadi Darban; Mohammad Javad Zarei

    2015-01-01

    .... The dynamic simulator of each mentioned unit was also developedaccording to population balance models with the help of MATLAB/Simulink environment and wasverified against the data from the literature...

  2. Muskrat population dynamics and vegetation utilization : A management plan : Quarterly progress report : April, May, June 1979

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Quarterly report on a study of muskrat population dynamics and vegetation utilization, being led by Utah State University for a doctorate dissertation. The study...

  3. The population dynamical implications of male-biased parasitism in different mating systems.

    Directory of Open Access Journals (Sweden)

    Martin R Miller

    Full Text Available Although there is growing evidence that males tend to suffer higher levels of parasitism than females, the implications of this for the population dynamics of the host population are not yet understood. Here we build on an established 'two-sex' model and investigate how increased susceptibility to infection in males affects the dynamics, under different mating systems. We investigate the effect of pathogenic disease at different case mortalities, under both monogamous and polygynous mating systems. If the case mortality is low, then male-biased parasitism appears similar to unbiased parasitism in terms of its effect on the population dynamics. At higher case mortalities, we identified significant differences between male-biased and unbiased parasitism. A host population may therefore be differentially affected by male-biased and unbiased parasitism. The dynamical outcome is likely to depend on a complex interaction between the host's mating system and demography, and the parasite virulence.

  4. Approximation of solutions to retarded differential equations with applications to population dynamics

    Directory of Open Access Journals (Sweden)

    D. Bahuguna

    2005-01-01

    Full Text Available We consider a retarded differential equation with applications to population dynamics. We establish the convergence of a finite-dimensional approximations of a unique solution, the existence and uniqueness of which are also proved in the process.

  5. Population dynamics, life-history traits of and habitat use by two ...

    African Journals Online (AJOL)

    African Journal of Aquatic Science ... Population dynamics and life-history traits of two sympatric nothobranchiid killifishes, Epiplatys bifasciatus and ... effort through daily spawning, short generation time, short life span and high mortality rate.

  6. Modeling regional population-employment dynamics across different sectors of the economy

    NARCIS (Netherlands)

    Graaff, T. de; Oort, F.G. van; Florax, R.

    2012-01-01

    An important subset of the literature on agglomeration externalities hypothesizes that intrasectoral and intersectoral relations are endogenously determined in models of local and regional economic growth. Remarkably, structural adjustment models describing the spatio-temporal dynamics of population

  7. The recovery, distribution, and population dynamics of wolves on the Scandinavian peninsula, 1978-1998

    National Research Council Canada - National Science Library

    Wabakken P; Sand H; Liberg O; Bjarvall A

    2001-01-01

    .... During 20 successive winters, from 1978 1979 to 1997 1998, the status, distribution, and dynamics of the wolf population were monitored by snow-tracking as a cooperative Swedish Norwegian project...

  8. Muskrat population dynamics and vegetation utilization : A management plan : Report on 1980 field season

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report for the 1980 field season on a study of muskrat population dynamics and vegetation utilization, being led by Utah State University for a doctorate...

  9. Assessing the importance of demographic parameters for population dynamics using Bayesian integrated population modeling.

    Science.gov (United States)

    Eacker, Daniel R; Lukacs, Paul M; Proffitt, Kelly M; Hebblewhite, Mark

    2017-06-01

    To successfully respond to changing habitat, climate or harvest, managers need to identify the most effective strategies to reverse population trends of declining species and/or manage harvest of game species. A classic approach in conservation biology for the last two decades has been the use of matrix population models to determine the most important vital rates affecting population growth rate (λ), that is, sensitivity. Ecologists quickly realized the critical role of environmental variability in vital rates affecting λ by developing approaches such as life-stage simulation analysis (LSA) that account for both sensitivity and variability of a vital rate. These LSA methods used matrix-population modeling and Monte Carlo simulation methods, but faced challenges in integrating data from different sources, disentangling process and sampling variation, and in their flexibility. Here, we developed a Bayesian integrated population model (IPM) for two populations of a large herbivore, elk (Cervus canadensis) in Montana, USA. We then extended the IPM to evaluate sensitivity in a Bayesian framework. We integrated known-fate survival data from radio-marked adults and juveniles, fecundity data, and population counts in a hierarchical population model that explicitly accounted for process and sampling variance. Next, we tested the prevailing paradigm in large herbivore population ecology that juvenile survival of neonates modeling in a Bayesian framework can provide multiple advantages. Our Bayesian LSA framework will provide a useful approach to addressing conservation challenges across a variety of species and data types. © 2017 by the Ecological Society of America.

  10. Fast game theory coupled to slow population dynamics: the case of domestic cat populations.

    Science.gov (United States)

    Auger, P; Pontier, D

    1998-02-01

    We study a deterministic model of a population where individuals alternatively adopt hawk and dove tactics. It is assumed that the hawk and dove individuals compete for some resources at a fast time scale. This fast part of the model is coupled to a slow part that describes the growth of the population. It is shown that, in a constant game matrix, the population grows according to a logistic curve whose r and K parameters are related to the payoff of the tactics. Results show that the highest population density is obtained when all individuals are dove. We also study a density-dependent game matrix for which the gain is a function of the population density. In this case, we show that two stable equilibria can occur, a first one at low density with a high proportion of hawk individuals and a second one at large density with a low proportion of hawk individuals. Our model is applied to domestic cat populations for which the behavior of individuals in competition with one another can be modeled by two tactics: hawk and dove. Such tactics change with density of population. The results of the model agree well with observed data: high-density populations of domestic cats are mainly doves, whereas low-density populations are mainly hawks.

  11. [The relationship between population dynamics and the process of development: an interdependence requiring the definition of population policies].

    Science.gov (United States)

    1989-01-01

    The case of Senegal is used to illustrate the impact of population dynamics on the economic development of a country and the process of creating a population policy. 1 of the 6 principles of the Kilimanjaro Program of Action concerning African population and autonomous development was the interdependence between population and development, but interest in the problem was only sporadic until the deepening of the economic crisis. Population growth is now regarded as a major constraint on improvement of welfare for the population. The population of the Sahel countries has almost doubled in the past 2 decades as a consequence of very high fertility rates and declining mortality rates. About 44% of the Sahel population is under 15 years old and only about 53% is aged 15-64. The population is unequally distributed and the proportion urban increased from 18 to 23% between 1982-85. The general opinion is that the African population is increasing more rapidly than available resources. From 1973-83, Senegal's gross national product increased by 2.2%/year on average, less than the population increase of 2.5%. Cereal production increased by 1%/year between 1973-81. Investments in agriculture have declined continuously since 1973. Cereal needs are on the order of 6.69 million tons, while production is only 4.4 million tons. According to the World Bank the literacy rate for 5 Sahel countries was only 15% in 1982, and only 35% of school aged children are enrolled. The constant increase of population is also putting pressure on health services. In response to these problems, Senegal developed its population policy in 3 phases. In the 1st phase, 3 commissions and a working group carried out research and documentation around the country, producing sectorial documents. In the 2nd phase, workshops and seminars were held for the critical examination of the sectorial documents, culminating in presentation of a synthesis to the National Commission on Population and to the

  12. An overview of the population dynamics in Malaysia.

    Science.gov (United States)

    Arshat, H; Tey Nai Peng

    1988-06-01

    Between 1900 and 1985 the population of Malaysia has increased from 2 million to 16 million. Before World War II most of the growth was due to immigration from China and India; after World War II it was due to natural increase. The crude birth rate appears to be leveling off at about 31.3 and the crude death rate at 5.3. At the current rate of growth the total population will be about 32 million by 2015. The proportion of urban population increased from 27% in 1979 to 34% in 1980. In 1980 83% of the population lived in Peninsular Malaysia (39% of the land area), and 17% lived in Sabah and Sarawak (61% of the land area). Population density ranges from 12 persons per square kilometer in Sarawak to 4521 in the Federal Republic of Kuala Lumpur. The median age of the population is 17.4 years; 40% are under 14, and 3.6% are over 65. In most age groups there are more women than men. The annual growth rate for Malays is higher than for Chinese and Indians, and Malays constituted 55% of the population in 1980. 34% are Chinese and 10% are Indian. Total fertility rate declined from 68/1000 in 1957 to 39/1000 in 1985. Malay fertility (4.8 children) is higher than either Indian (2.9) or Chinese (2.7) Malay fertility has been increasing while that of Indians and Chinese is decreasing due to contraception. Also, among all 3 groups age at marriage has increased. Data from the 1984/85 Malaysian Population and Family Survey show that the differential fertility of the 3 groups is due largely to rural/urban distribution, education, and work patterns. Ideal family size, according to the survey, is 4.8. The National Population and Family Development Program would like to achieve a growth rate of 2%/year, and family planning knowledge has become virtually universal. KAP surveys show that by 1984 contraceptive prevalence was 51%; however 42% of all eligible women were using unreliable methods. In terms of efficient methods, contraceptive prevalence rate was 16% for Malays, 47% for Chinese

  13. Ecological change, group territoriality, and population dynamics in Serengeti lions.

    Science.gov (United States)

    Packer, Craig; Hilborn, Ray; Mosser, Anna; Kissui, Bernard; Borner, Markus; Hopcraft, Grant; Wilmshurst, John; Mduma, Simon; Sinclair, Anthony R E

    2005-01-21

    Territorial behavior is expected to buffer populations against short-term environmental perturbations, but we have found that group living in African lions causes a complex response to long-term ecological change. Despite numerous gradual changes in prey availability and vegetative cover, regional populations of Serengeti lions remained stable for 10- to 20-year periods and only shifted to new equilibria in sudden leaps. Although gradually improving environmental conditions provided sufficient resources to permit the subdivision of preexisting territories, regional lion populations did not expand until short-term conditions supplied enough prey to generate large cohorts of surviving young. The results of a simulation model show that the observed pattern of "saltatory equilibria" results from the lions' grouping behavior.

  14. Population, environment dynamics, poverty and quality of life in China.

    Science.gov (United States)

    Gu, B

    1996-12-01

    This article focuses on the growth in poverty, environmental concerns, and Chinese government efforts to eliminate poverty with integrated programs. China had 1.2 billion people in February 1995, or 20% of total world population on 7% of the world's arable land. The rate of natural increase was 1.1% in 1996. China's population could double to 2.4 billion by 2060. About 14 million people are added every year. China has about 300 million women of childbearing age. Even with 1 child per woman, population would grow by 300 million. 18 provinces have population growth over the national average of 1.49%. Many of these provinces are also provinces with high population density, high poverty ratios, and higher than 2 birth orders. The highest growth is in western China. Poor households have a lower quality of life, more disabled members, high rates of endemic disease, and illiteracy. Among the very poor without adequate food or clothing, environmental protection is a meaningless concept. Poverty alleviation strategies have shifted from relief to economic development. State support combined with local resources in a pooling approach pays for poverty alleviation programs. The central government's share will increase until the year 2000. The number of poor was 80 million in 1994 (9% of total population) living in 592 poor counties in remote and mountainous areas. The number of poor was reduced to 65 million in 1996. An integrated approach of family planning and poverty alleviation operates in Jinzhai County of Anhui province. China is determined to reorient to a "service-oriented, client- centered, woman-sensitive, and rural-emphasized approach."

  15. Population dynamics and range expansion in nine-banded armadillos.

    Directory of Open Access Journals (Sweden)

    William J Loughry

    Full Text Available Understanding why certain species can successfully colonize new areas while others do not is a central question in ecology. The nine-banded armadillo (Dasypus novemcinctus is a conspicuous example of a successful invader, having colonized much of the southern United States in the last 200 years. We used 15 years (1992-2006 of capture-mark-recapture data from a population of armadillos in northern Florida in order to estimate, and examine relationships among, various demographic parameters that may have contributed to this ongoing range expansion. Modeling across a range of values for γ, the probability of juveniles surviving in the population until first capture, we found that population growth rates varied from 0.80 for γ = 0.1, to 1.03 for γ = 1.0. Growth rates approached 1.0 only when γ ≥ 0.80, a situation that might not occur commonly because of the high rate of disappearance of juveniles. Net reproductive rate increased linearly with γ, but life expectancy (estimated at 3 years was independent of γ. We also found that growth rates were lower during a 3-year period of hardwood removal that removed preferred habitat than in the years preceding or following. Life-table response experiment (LTRE analysis indicated the decrease in growth rate during logging was primarily due to changes in survival rates of adults. Likewise, elasticity analyses of both deterministic and stochastic population growth rates revealed that survival parameters were more influential on population growth than were those related to reproduction. Collectively, our results are consistent with recent theories regarding biological invasions which posit that populations no longer at the leading edge of range expansion do not exhibit strong positive growth rates, and that high reproductive output is less critical in predicting the likelihood of successful invasion than are life-history strategies that emphasize allocation of resources to future, as opposed to current

  16. Phylogeography, population dynamics, and molecular evolution of European bat lyssaviruses

    DEFF Research Database (Denmark)

    Davis, P.L.; Holmes, E.C.; Larrous, F.

    2005-01-01

    origin, and population growth rates of EBLV-1. Our study encompassed data from 12 countries collected over a time span of 35 years and focused on the glycoprotein (G) and nucleoprotein (N) genes. We show that although the two subtypes of EBLV-1-EBLV-1a and EBLV-lb-have both grown at a low exponential...... rate since their introduction into Europe, they have differing population structures and dispersal patterns. Furthermore, there were strong constraints against amino acid change in both EBLV-1 and EBLV-2, as reflected in a low ratio of nonsynonymous to synonymous substitutions per site, particularly...

  17. The dynamics of discrete populations and series of events

    CERN Document Server

    Hopcraft, Keith Iain; Ridley, Kevin D

    2014-01-01

    IntroductionReferencesStatistical PreliminariesIntroductionProbability DistributionsMoment-Generating FunctionsDiscrete ProcessesSeries of EventsSummaryFurther ReadingMarkovian Population ProcessesIntroductionBirths and DeathsImmigration and the Poisson ProcessThe Effect of MeasurementCorrelation of CountsSummaryFurther ReadingThe Birth-Death-Immigration ProcessIntroductionRate Equations for the ProcessEquation for the Generating FunctionGeneral Time-Dependent SolutionFluctuation Characteristics of a Birth-Death-Immigration PopulationSampling and Measurement ProcessesCorrelation of CountsSumma

  18. Transients drive the demographic dynamics of plant populations in variable environments

    DEFF Research Database (Denmark)

    McDonald, Jenni L; Stott, Iain; Townley, Stuart;

    2016-01-01

    clear patterns related to growth form. We find a surprising tendency for plant populations to boom rather than bust in response to temporal changes in vital rates and that stochastic growth rates increase with increasing tendency to boom. Synthesis. Transient dynamics contribute significantly......The dynamics of structured plant populations in variable environments can be decomposed into the ‘asymptotic’ growth contributed by vital rates, and ‘transient’ growth caused by deviation from stable stage structure. We apply this framework to a large, global data base of longitudinal studies...... of projection matrix models for plant populations. We ask, what is the relative contribution of transient boom and bust to the dynamic trajectories of plant populations in stochastic environments? Is this contribution patterned by phylogeny, growth form or the number of life stages per population and per...

  19. Modeling complex spatial dynamics of two-population interaction in urbanization process

    CERN Document Server

    Chen, Yanguang

    2013-01-01

    This paper is mainly devoted to lay an empirical foundation for further research on complex spatial dynamics of two-population interaction. Based on the US population census data, a rural and urban population interaction model is developed. Subsequently a logistic equation on percentage urban is derived from the urbanization model so that spatial interaction can be connected mathematically with logistic growth. The numerical experiment by using the discretized urban-rural population interaction model of urbanization shows a period-doubling bifurcation and chaotic behavior, which is identical in patterns to those from the simple mathematical models of logistic growth in ecology. This suggests that the complicated dynamics of logistic growth may come from some kind of the nonlinear interaction. The results from this study help to understand urbanization, urban-rural population interaction, chaotic dynamics, and spatial complexity of geographical systems.

  20. Report on Honduras: ripples in the pond--the financial crisis and remittances to chronically ill patients in Honduras.

    Science.gov (United States)

    Piette, John D; Mendoza-Avelares, Milton O; Chess, Laura; Milton, Evan C; Matiz Reyes, Armando; Rodriguez-Saldaña, Joel

    2012-01-01

    The U.S. financial crisis has affected employment opportunities for Latino immigrants, and this could affect their ability to send financial assistance, or "remittances", to chronically ill family members in their home country. In a cross-sectional survey of 624 chronically ill adults conducted in Honduras between June and August 2009, respondents reported their receipt of remittances, health service use, and cost-related access barriers. Fifty-four percent of respondents reported relatives living outside the country, and of this group, 66 percent (37% of the overall sample) received remittances. Seventy-four percent of respondents receiving remittances reported a decrease over the prior year, mostly due to job losses among their relatives abroad. Respondents reporting reductions in remittances received significantly less per month, on average, than those without a reduction (US $170 vs. $234; p = 0.01). In multivariate models, respondents experiencing a reduction in remittances used fewer health services and medications due to cost concerns. Remittance payments from relatives resident in the United States are a major source of income for chronically ill individuals in Latin America. Most recipients of remittances reported a reduction during the financial downturn that affected their access to care.

  1. Effective population size and evolutionary dynamics in outbred laboratory populations of Drosophila

    Indian Academy of Sciences (India)

    Laurence D. Mueller; Amitabh Joshi; Marta Santos; Michael R. Rose

    2013-12-01

    Census population size, sex-ratio and female reproductive success were monitored in 10 laboratory populations of Drosophila melanogaster selected for different ages of reproduction. With this demographic information, we estimated eigenvalue, variance and probability of allele loss effective population sizes. We conclude that estimates of effective size based on genefrequency change at a few loci are biased downwards. We analysed the relative roles of selection and genetic drift in maintaining genetic variation in laboratory populations of Drosophila. We suggest that rare, favourable genetic variants in our laboratory populations have a high chance of being lost if their fitness effect is weak, e.g. 1% or less. However, if the fitness effect of this variation is 10% or greater, these rare variants are likely to increase to high frequency. The demographic information developed in this study suggests that some of our laboratory populations harbour more genetic variation than expected. One explanation for this finding is that part of the genetic variation in these outbred laboratory Drosophila populations may be maintained by some form of balancing selection. We suggest that, unlike bacteria, medium-term adaptation of laboratory populations of fruit flies is not primarily driven by new mutations, but rather by changes in the frequency of preexisting alleles.

  2. Population dynamics of active and total ciliate populations in arable soil amended with wheat

    DEFF Research Database (Denmark)

    Ekelund, F.; Frederiksen, Helle B.; Ronn, R.

    2002-01-01

    of ciliate growth, the population of cystic ciliates increased 100-fold. We suggest that internal population regulation is the major factor governing ciliate encystment and that the rate of encystment depends on ciliate density. This model provides a quantitative explanation of ciliatostasis and can explain...

  3. Food-dependent individual growth and population dynamics in fishes

    NARCIS (Netherlands)

    L. Persson; A.M. de Roos

    2006-01-01

    It is long since well established that growth and development in fish individuals are heavily dependent on food intake. Yet, this dependence of individual development on food levels has only to a limited extent been taken into consideration when studying fish population and community processes. Usin

  4. Predicting when climate-driven phenotypic change affects population dynamics

    NARCIS (Netherlands)

    McLean, Nina; Lawson, C.R.; Leech, David; Van de Pol, M.

    2016-01-01

    Species' responses to climate change are variable and diverse, yet our understanding of how different responses (e.g. physiological, behavioural, demographic) relate and how they affect the parameters most relevant for conservation (e.g. population persistence) is lacking. Despite this, studies that

  5. A stage-based model of manatee population dynamics

    Science.gov (United States)

    Runge, M.C.; Langtimm, C.A.; Kendall, W.L.

    2004-01-01

    A stage-structured population model for the Florida manatee (Trichechus manatus latirostris) was developed that explicitly incorporates uncertainty in parameter estimates. The growth rates calculated with this model reflect the status of the regional populations over the most recent 10-yr period. The Northwest and Upper St. Johns River regions have growth rates (8) of 1.037 (95% interval, 1.016?1.056) and 1.062 (1.037?1.081), respectively. The Southwest region has a growth rate of 0.989 (0.946?1.024), suggesting this population has been declining at about 1.1% per year. The estimated growth rate in the Atlantic region is 1.010 (0.988?1.029), but there is some uncertainty about whether adult survival rates have been constant over the last 10 yr; using the mean survival rates from the most recent 5-yr period, the estimated growth rate in this region is 0.970 (0.938?0.998). Elasticity analysis indicates that the most effective management actions should seek to increase adult survival rates. Decomposition of the uncertainty in the growth rates indicates that uncertainty about population status can best be reduced through increased monitoring of adult survival rate.

  6. Population dynamics of Lanyu Scops Owls (Otus elegans botelensis)

    Science.gov (United States)

    L. L. Severinghaus

    1997-01-01

    Monthly visits to Lanyu Island have been made to study Lanyu Scops Owls (Otus elegans botelensis) since 1986. This population has been surveyed by regular census and playback counts, by color banding, by monitoring the survival, reproduction and movements of individual owls, and by mapping and documenting the change in nest trees.

  7. From homogeneous eigenvalue problems to two-sex population dynamics.

    Science.gov (United States)

    Thieme, Horst R

    2017-03-08

    Enclosure theorems are derived for homogeneous bounded order-preserving operators and illustrated for operators involving pair-formation functions introduced by Karl-Peter Hadeler in the late 1980s. They are applied to a basic discrete-time two-sex population model and to the relation between the basic turnover number and the basic reproduction number.

  8. NUEVOS REGISTROS PARA LA FLORA DE HONDURAS Y EL PARQUE NACIONAL MONTAÑA DE CELAQUE

    Directory of Open Access Journals (Sweden)

    Hermes VEGA

    2016-01-01

    Full Text Available Se registran 11 novedades para la flora de Honduras a partir de ejemplares recolectados en el Parque Nacional Montaña Celaque. Los nuevos registros son: Tillandsia mateoensis (Bromeliaceae, Diastema affine (Gesneriaceae, Scutellaria costaricana (Lamiaceae, Miconia contrerasii (Melastomataceae, Acianthera violacea, Dendrophylax porrectus, Epidendrum santaclarense, Lepanthes enca-barcenae, L. fratercula, L. isabelae y Sarcoglottis schaffneri (Orchidaceae. Por otra parte, Potosia guatemalensis es sinonimizado bajo S. schaffneri. Se incluyen fotos de todas las especies, hábitats y un mapa de distribución con sus localidades en Honduras.

  9. Rickettsial infections in ticks from reptiles, birds and humans in Honduras.

    Science.gov (United States)

    Novakova, Marketa; Literak, Ivan; Chevez, Luis; Martins, Thiago F; Ogrzewalska, Maria; Labruna, Marcelo B

    2015-09-01

    Ticks were collected from captive reptiles, wild birds, and incidentally from humans at two locations in Honduras and part of these were tested for the presence of Rickettsia using polymerase chain reaction. The following species of ticks were found: Amblyomma dissimile on Iguanidae reptiles, Amblyomma longirostre and Amblyomma nodosum on birds, and Amblyomma mixtum (Amblyomma cajennense complex) on humans. A. dissimile was infected with Rickettsia sp. strain Colombianensi. Both A. longirostre and A. mixtum were infected with Candidatus 'Rickettsia amblyommii'. This study provides the first report of rickettsial infections in ticks from reptiles, birds and humans in Honduras. New host - Amblyomma tick associations are documented.

  10. Population dynamics in central and edge populations of a narrowly endemic plant.

    Science.gov (United States)

    Aikens, Melissa L; Roach, Deborah A

    2014-07-01

    Species' range limits can be caused by environmental gradients, and in such cases, abundance is thought to be highest in the center of a species range and decline towards the edge (the abundant-center model). Although in theory decreased abundance is caused by a decline in performance at the edge, it has been shown that performance and abundance are not necessarily related. Few studies have compared abundance and performance in center and edge populations of endemic species, whose ranges may be restricted by the availability of specialized habitat rather than environmental gradients across their range. Additionally, range-wide studies that examine both northern and southern edge populations are rare. We used Roan Mountain rattlesnake-root (Prenanthes roanensis), a perennial plant endemic to the Southern Appalachians (USA), to compare abundance and performance between central populations and populations at the northern and southern edges of the range. To account for multiple fitness components across the life cycle, we measured performance of edge populations as vital-rate contributions to population growth rate compared to the center. Abundance did not decline at the range edge, but some vital-rate contributions were lower in edge populations compared to central populations. However, each edge population differed in which vital-rate contributions were lower compared to the center. Our results do not support the abundant-center model, and it appears that local factors are important in structuring the range of this endemic species. It is important to recognize that when implementing conservation or management plans, populations in close proximity may have substantial variation in demographic rates due to differences in the local environment.

  11. Breeding site heterogeneity reduces variability in frog recruitment and population dynamics

    Science.gov (United States)

    McCaffery, Rebecca M.; Eby, Lisa A.; Maxell, Bryce A.; Corn, Paul Stephen

    2013-01-01

    Environmental stochasticity can have profound effects on the dynamics and viability of wild populations, and habitat heterogeneity provides one mechanism by which populations may be buffered against the negative effects of environmental fluctuations. Heterogeneity in breeding pond hydroperiod across the landscape may allow amphibian populations to persist despite variable interannual precipitation. We examined recruitment dynamics over 10 yr in a high-elevation Columbia spotted frog (Rana luteiventris) population that breeds in ponds with a variety of hydroperiods. We combined these data with matrix population models to quantify the consequences of heterogeneity in pond hydroperiod on net recruitment (i.e. number of metamorphs produced) and population growth rates. We compared our heterogeneous system to hypothetical homogeneous environments with only ephemeral ponds, only semi-permanent ponds, and only permanent ponds. We also examined the effects of breeding pond habitat loss on population growth rates. Most eggs were laid in permanent ponds each year, but survival to metamorphosis was highest in the semi-permanent ponds. Recruitment success varied by both year and pond type. Net recruitment and stochastic population growth rate were highest under a scenario with homogeneous semi-permanent ponds, but variability in recruitment was lowest in the scenario with the observed heterogeneity in hydroperiods. Loss of pond habitat decreased population growth rate, with greater decreases associated with loss of permanent and semi-permanent habitat. The presence of a diversity of pond hydroperiods on the landscape will influence population dynamics, including reducing variability in recruitment in an uncertain climatic future.

  12. Quantification of Dynamic Excitation Potential of Pedestrian Population Crossing Footbridges

    Directory of Open Access Journals (Sweden)

    Stana Žcaronivanović

    2011-01-01

    Full Text Available Due to their slenderness, many modern footbridges may vibrate significantly under pedestrian traffic. Consequently, the vibration serviceability of these structures under human-induced dynamic loading is becoming their governing design criterion. Many current vibration serviceability design guidelines, concerned with prediction of the vibration in the vertical direction, estimate a single response level that corresponds to an "average" person crossing the bridge with the step frequency that matches a footbridge natural frequency. However, different pedestrians have different dynamic excitation potential, and therefore could generate significantly different vibration response of the bridge structure. This paper aims to quantify this potential by estimating the range of structural vibrations (in the vertical direction that could be induced by different individuals and the probability of occurrence of any particular vibration level. This is done by introducing the inter- and intra-subject variability in the walking force modelling. The former term refers to inability of a pedestrian to induce an exactly the same force with each step while the latter refers to different forces (in terms of their magnitude, frequency and crossing speed induced by different people. Both types of variability are modelled using the appropriate probability density functions. The probability distributions were then implemented into a framework procedure for vibration response prediction under a single person excitation. Instead of a single response value obtained using currently available design guidelines, this new framework yields a range of possible acceleration responses induced by different people and a distribution function for these responses. The acceleration ranges estimated are then compared with experimental data from two real-life footbridges. The substantial differences in the dynamic response induced by different people are obtained in both the numerical and

  13. 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.

  14. Structural perturbations to population skeletons: transient dynamics, coexistence of attractors and the rarity of chaos.

    Directory of Open Access Journals (Sweden)

    Brajendra K Singh

    Full Text Available Simple models of insect populations with non-overlapping generations have been instrumental in understanding the mechanisms behind population cycles, including wild (chaotic fluctuations. The presence of deterministic chaos in natural populations, however, has never been unequivocally accepted. Recently, it has been proposed that the application of chaos control theory can be useful in unravelling the complexity observed in real population data. This approach is based on structural perturbations to simple population models (population skeletons. The mechanism behind such perturbations to control chaotic dynamics thus far is model dependent and constant (in size and direction through time. In addition, the outcome of such structurally perturbed models is [almost] always equilibrium type, which fails to commensurate with the patterns observed in population data.We present a proportional feedback mechanism that is independent of model formulation and capable of perturbing population skeletons in an evolutionary way, as opposed to requiring constant feedbacks. We observe the same repertoire of patterns, from equilibrium states to non-chaotic aperiodic oscillations to chaotic behaviour, across different population models, in agreement with observations in real population data. Model outputs also indicate the existence of multiple attractors in some parameter regimes and this coexistence is found to depend on initial population densities or the duration of transient dynamics. Our results suggest that such a feedback mechanism may enable a better understanding of the regulatory processes in natural populations.

  15. Dynamics of Microbial Populations during Fermentation of Wines from the Utiel-Requena Region of Spain

    OpenAIRE

    Pardo, Isabel; García, María José; Zúñiga, Manuel; Uruburu, Federico

    1989-01-01

    The dynamics of fungi, yeasts, and lactic acid bacteria during fermentation of four musts were studied. Fungi disappeared quickly in the fermenting must. The lactic acid bacteria population diminished during alcoholic fermentation, then they increased and performed malolactic fermentation. Yeasts grew quickly, reaching maximum populations at different times depending on the vinification treatment.

  16. Eel population dynamic and habitat relationships in the European southern tip.

    Directory of Open Access Journals (Sweden)

    Ramon José De Miguel

    2015-11-01

    According to our previous results, the eel population in the most southern region in Europe shows similar averages in dynamic population indicators compared to other European areas. On the other hand, no environmental predictors showed major influence on catchability, except for, those related to previous abundant rainfalls.

  17. Strong persistent growth differences govern individual performance and population dynamics in a tropical forest understorey palm

    NARCIS (Netherlands)

    Jansen, M.; Zuidema, P.A.; Anten, N.P.R.; Martínez-Ramos, M.

    2012-01-01

    1. Persistent variation in growth rate between individual plants can have strong effects on population dynamics as fast growers reach the reproductive size at an earlier age and thus potentially contribute more to population growth than slow growers. In tropical forests, such persistent growth diffe

  18. Site-specific dynamics in remnant populations of Northern Wheatears Oenanthe oenanthe in the Netherlands

    NARCIS (Netherlands)

    Oosten, van H.H.; Turnhout, van C.; Hallmann, C.A.; Majoor, F.; Roodbergen, M.; Schekkerman, H.; Versluijs, R.; Waasdorp, S.; Siepel, H.

    2015-01-01

    Dynamics of populations may be synchronized at large spatial scales, indicating driving forces acting beyond local scales, but may also vary locally as a result of site-specific conditions. Conservation measures for fragmented and declining populations may need to address such local effects to avoid

  19. Density dependence and population dynamics of black rhinos (Diceros bicornis michaeli) in Kenya's rhino sanctuaries

    NARCIS (Netherlands)

    Ouma, B.O.; Amin, R.; Langevelde, van F.; Leader-Williams, N.

    2010-01-01

    Density-dependent feedback mechanisms provide insights into the population dynamics and interactions of large herbivores with their ecosystem. Sex ratio also has particularly important implications for growth rates of many large mammal populations through its influence on reproductive potential. The

  20. Weed populations and crop rotations: exploring dynamics of a structured periodic system

    NARCIS (Netherlands)

    Mertens, S.K.; Bosch, F. van den; Heesterbeek, J.A.P.

    2002-01-01

    The periodic growing of a certain set of crops in a prescribed order, called a crop rotation, is considered to be an important tool for managing weed populations. Nevertheless, the effects of crop rotations on weed population dynamics are not well understood. Explanations for rotation effects on

  1. Modelling of population dynamics of red king crab using Bayesian approach

    Directory of Open Access Journals (Sweden)

    Bakanev Sergey ...

    2012-10-01

    Modeling population dynamics based on the Bayesian approach enables to successfully resolve the above issues. The integration of the data from various studies into a unified model based on Bayesian parameter estimation method provides a much more detailed description of the processes occurring in the population.

  2. demoniche – an R-package for simulating spatially-explicit population dynamics

    DEFF Research Database (Denmark)

    Nenzén, Hedvig K.; Swab, Rebecca Marie; Keith, David A.

    2012-01-01

    demoniche is a freely available R-package which simulates stochastic population dynamics in multiple populations of a species. A demographic model projects population sizes utilizing several transition matrices that can represent impacts on species growth. The demoniche model offers options...... for setting demographic stochasticity, carrying capacity, and dispersal. The demographic projection in each population is linked to spatially-explicit niche values, which affect the species growth. With the demoniche package it is possible to compare the influence of scenarios of environmental changes...... on future population sizes, extinction probabilities, and range shifts of species....

  3. Two-Population Dynamics in a Growing Network Model

    CERN Document Server

    Ivanova, Kristinka

    2011-01-01

    We introduce a growing network evolution model with nodal attributes. The model describes the interactions between potentially violent V and non-violent N agents who have different affinities in establishing connections within their own population versus between the populations. The model is able to generate all stable triads observed in real social systems. In the framework of rate equations theory, we employ the mean-field approximation to derive analytical expressions of the degree distribution and the local clustering coefficient for each type of nodes. Analytical derivations agree well with numerical simulation results. The assortativity of the potentially violent network qualitatively resembles the connectivity pattern in terrorist networks that was recently reported. The assortativity of the network driven by aggression shows clearly different behavior than the assortativity of the networks with connections of non-aggressive nature in agreement with recent empirical results of an online social system.

  4. A DYNAMICAL SIGNATURE OF MULTIPLE STELLAR POPULATIONS IN 47 TUCANAE

    Energy Technology Data Exchange (ETDEWEB)

    Richer, Harvey B.; Heyl, Jeremy [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Anderson, Jay; Kalirai, Jason S. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Shara, Michael M. [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Dotter, Aaron [Research School of Astronomy and Astrophysics, Australian National University, Weston, ACT 2611 (Australia); Fahlman, Gregory G. [National Research Council, Herzberg Institute of Astrophysics, Victoria, BC V9E 2E7 (Canada); Rich, R. Michael, E-mail: richer@astro.ubc.ca, E-mail: heyl@phas.ubc.ca, E-mail: jayander@stsci.edu, E-mail: jkalarai@stsci.edu, E-mail: mshara@amnh.org, E-mail: aaron.dotter@gmail.com, E-mail: greg.fahlman@nrc-cnrc.gc.ca, E-mail: rmr@astro.ucla.edu [Division of Astronomy and Astrophysics, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2013-07-01

    Based on the width of its main sequence, and an actual observed split when viewed through particular filters, it is widely accepted that 47 Tucanae contains multiple stellar populations. In this contribution, we divide the main sequence of 47 Tuc into four color groups, which presumably represent stars of various chemical compositions. The kinematic properties of each of these groups are explored via proper motions, and a strong signal emerges of differing proper-motion anisotropies with differing main-sequence color; the bluest main-sequence stars exhibit the largest proper-motion anisotropy which becomes undetectable for the reddest stars. In addition, the bluest stars are also the most centrally concentrated. A similar analysis for Small Magellanic Cloud stars, which are located in the background of 47 Tuc on our frames, yields none of the anisotropy exhibited by the 47 Tuc stars. We discuss implications of these results for possible formation scenarios of the various populations.

  5. Dynamics in the devolopment of donkey population in Bulgaria

    Directory of Open Access Journals (Sweden)

    R. Vlaeva

    2017-03-01

    Full Text Available The aim of the recent study was to trace back the development of the donkey population in Bulgaria for the period 1950 – 2015. For that purpose the data from the National Statistic Institute and FAO was processed and other sources related to the problem were analyzed. Donkeys in Bulgaria used to be a comparatively large share of the traction power animals in the past, with the occurance of the social and economical changes after 1990 their number was dramatically reduced. This process is most noticeable after 2000, when for five year period until 2005 the donkey population in Bulgaria drops down from 207000 to 90000 individuals, as in 2013 this number falls down to 35000 according to FAO.

  6. Worldwide Phylogenetic Distributions and Population Dynamics of the Genus Histoplasma.

    Directory of Open Access Journals (Sweden)

    Marcus de M Teixeira

    2016-06-01

    Full Text Available Histoplasma capsulatum comprises a worldwide complex of saprobiotic fungi mainly found in nitrogen/phosphate (often bird guano enriched soils. The microconidia of Histoplasma species may be inhaled by mammalian hosts, and is followed by a rapid conversion to yeast that can persist in host tissues causing histoplasmosis, a deep pulmonary/systemic mycosis. Histoplasma capsulatum sensu lato is a complex of at least eight clades geographically distributed as follows: Australia, Netherlands, Eurasia, North American classes 1 and 2 (NAm 1 and NAm 2, Latin American groups A and B (LAm A and LAm B and Africa. With the exception of the Eurasian cluster, those clades are considered phylogenetic species.Increased Histoplasma sampling (n = 234 resulted in the revision of the phylogenetic distribution and population structure using 1,563 aligned nucleotides from four protein-coding regions. The LAm B clade appears to be divided into at least two highly supported clades, which are geographically restricted to either Colombia/Argentina or Brazil respectively. Moreover, a complex population genetic structure was identified within LAm A clade supporting multiple monophylogenetic species, which could be driven by rapid host or environmental adaptation (~0.5 MYA. We found two divergent clades, which include Latin American isolates (newly named as LAm A1 and LAm A2, harboring a cryptic cluster in association with bats.At least six new phylogenetic species are proposed in the Histoplasma species complex supported by different phylogenetic and population genetics methods, comprising LAm A1, LAm A2, LAm B1, LAm B2, RJ and BAC-1 phylogenetic species. The genetic isolation of Histoplasma could be a result of differential dispersion potential of naturally infected bats and other mammals. In addition, the present study guides isolate selection for future population genomics and genome wide association studies in this important pathogen complex.

  7. Worldwide Phylogenetic Distributions and Population Dynamics of the Genus Histoplasma

    Science.gov (United States)

    Taylor, Maria L.; Gómez, Beatriz L.; Theodoro, Raquel C.; de Hoog, Sybren; Engelthaler, David M.; Zancopé-Oliveira, Rosely M.; Felipe, Maria S. S.

    2016-01-01

    Background Histoplasma capsulatum comprises a worldwide complex of saprobiotic fungi mainly found in nitrogen/phosphate (often bird guano) enriched soils. The microconidia of Histoplasma species may be inhaled by mammalian hosts, and is followed by a rapid conversion to yeast that can persist in host tissues causing histoplasmosis, a deep pulmonary/systemic mycosis. Histoplasma capsulatum sensu lato is a complex of at least eight clades geographically distributed as follows: Australia, Netherlands, Eurasia, North American classes 1 and 2 (NAm 1 and NAm 2), Latin American groups A and B (LAm A and LAm B) and Africa. With the exception of the Eurasian cluster, those clades are considered phylogenetic species. Methodology/Principal Findings Increased Histoplasma sampling (n = 234) resulted in the revision of the phylogenetic distribution and population structure using 1,563 aligned nucleotides from four protein-coding regions. The LAm B clade appears to be divided into at least two highly supported clades, which are geographically restricted to either Colombia/Argentina or Brazil respectively. Moreover, a complex population genetic structure was identified within LAm A clade supporting multiple monophylogenetic species, which could be driven by rapid host or environmental adaptation (~0.5 MYA). We found two divergent clades, which include Latin American isolates (newly named as LAm A1 and LAm A2), harboring a cryptic cluster in association with bats. Conclusions/Significance At least six new phylogenetic species are proposed in the Histoplasma species complex supported by different phylogenetic and population genetics methods, comprising LAm A1, LAm A2, LAm B1, LAm B2, RJ and BAC-1 phylogenetic species. The genetic isolation of Histoplasma could be a result of differential dispersion potential of naturally infected bats and other mammals. In addition, the present study guides isolate selection for future population genomics and genome wide association studies in this

  8. Recovery of methanotrophs from disturbance: population dynamics, evenness and functioning.

    Science.gov (United States)

    Ho, Adrian; Lüke, Claudia; Frenzel, Peter

    2011-04-01

    Biodiversity is claimed to be essential for ecosystem functioning, but is threatened by anthropogenic disturbances. Prokaryotes have been assumed to be functionally redundant and virtually inextinguishable. However, recent work indicates that microbes may well be sensitive to environmental disturbance. Focusing on methane-oxidizing bacteria as model organisms, we simulated disturbance-induced mortality by mixing native with sterilized paddy soil in two ratios, 1:4 and 1:40, representing moderate and severe die-offs. Disturbed microcosms were compared with an untreated control. Recovery of activity and populations was followed over 4 months by methane uptake measurements, pmoA-qPCR, pmoA-based terminal restriction fragment length polymorphism and a pmoA-based diagnostic microarray. Diversity and evenness of methanotrophs decreased in disturbed microcosms, but functioning was not compromised. We consistently observed distinctive temporal shifts between type I and type II methanotrophs, and a rapid population growth leading to even higher cell numbers comparing disturbed microcosms with the control. Overcompensating mortality suggested that population size in the control was limited by competition with other bacteria. Overall, methanotrophs showed a remarkable ability to compensate for die-offs.

  9. Evolutionary dynamics of fluctuating populations with strong mutualism

    Science.gov (United States)

    Chotibut, Thiparat; Nelson, David

    2013-03-01

    Evolutionary game theory with finite interacting populations is receiving increased attention, including subtle phenomena associated with number fluctuations, i.e., ``genetic drift.'' Models of cooperation and competition often utilize a simplified Moran model, with a strictly fixed total population size. We explore a more general evolutionary model with independent fluctuations in the numbers of two distinct species, in a regime characterized by ``strong mutualism.'' The model has two absorbing states, each corresponding to fixation of one of the two species, and allows exploration of the interplay between growth, competition, and mutualism. When mutualism is favored, number fluctuations eventually drive the system away from a stable fixed point, characterized by cooperation, to one of the absorbing states. Well-mixed populations will thus be taken over by a single species in a finite time, despite the bias towards cooperation. We calculate both the fixation probability and the mean fixation time as a function of the initial conditions and carrying capacities in the strong mutualism regime, using the method of matched asymptotic expansions. Our results are compared to computer simulations.

  10. Population dynamics of mallards breeding in eastern Washington

    Science.gov (United States)

    Dugger, Bruce D.; Coluccy, John M.; Dugger, Katie M.; Fox, Trevor T.; Kraege, Donald K.; Petrie, Mark J.

    2016-01-01

    Variation in regional population trends for mallards breeding in the western United States indicates that additional research into factors that influence demographics could contribute to management and understanding the population demographics of mallards across North America. We estimated breeding incidence and adult female, nest, and brood survival in eastern Washington in 2006 and 2007 by monitoring female mallards with radio telemetry and tested how those parameters were influenced by study year (2006 vs. 2007), landscape type (agricultural vs. natural), and age (second year [SY] vs. after second year [ASY]). We also investigated the effects of female body condition and capture date on breeding incidence, and nest initiation date and hatch date on nest and brood survival, respectively. We included population parameters in a stage-based demographic model and conducted a perturbation analysis to identify which vital rates were most influential on population growth rate (λ). Adult female survival was best modeled with a constant weekly survival rate (0.994, SE = 0.003). Breeding incidence differed between years and was higher for birds in better body condition. Nest survival was higher for ASY females (0.276, SE = 0.118) than SY females (0.066, SE = 0.052), and higher on publicly managed lands (0.383, SE = 0.212) than agricultural (0.114, SE = 0.058) landscapes. Brood survival was best modeled with a constant rate for the 7-week monitoring period (0.50, SE = 0.155). The single variable having the greatest influence on λ was non-breeding season survival, but the combination of parameters from the breeding grounds explained a greater percent of the variance in λ. Mallard population growth rate was most sensitive to changes in non-breeding survival, nest success, brood survival, and breeding incidence. Future management decisions should focus on activities that improve these vital rates if managers want to increase the production of

  11. Dynamics of biomass and population density of fucus algae of the Kola Bay, Barents Sea

    Directory of Open Access Journals (Sweden)

    Malavenda S. S.

    2016-03-01

    Full Text Available The long-term dynamics of biomass and population density of Fucus distichus and F. vesiculosus in the southern and middle knees of the Kola Bay have been analyzed. The feedbacks between these parameters and their changes over several years have been revealed for the first time. Changing the prevalence of biomass and population density can be considered as an adaptation at the population level to maintain the stability of algae communities in chronic pollution

  12. Population Dynamics of Soil Pseudomonads in the Rhizosphere of Potato (Solanum tuberosum L.)

    OpenAIRE

    Joyce E Loper; Haack, Caryn; Schroth, Milton N.

    1985-01-01

    Rhizosphere population dynamics of seven Pseudomonas fluorescens and Pseudomonas putida strains isolated from rhizospheres of various agricultural plants were studied on potato (Solanum tuberosum L.) in field soil under controlled environmental conditions. Rhizosphere populations of two strains (B10 and B4) were quantitatively related to initial seed piece inoculum levels when plants were grown at −0.3 bar matric potential. At a given inoculum level, rhizosphere populations of strain B4 were ...

  13. The population and evolutionary dynamics of homologous gene recombination in bacterial populations.

    Directory of Open Access Journals (Sweden)

    Bruce R Levin

    2009-08-01

    Full Text Available In bacteria, recombination is a rare event, not a part of the reproductive process. Nevertheless, recombination -- broadly defined to include the acquisition of genes from external sources, i.e., horizontal gene transfer (HGT -- plays a central role as a source of variation for adaptive evolution in many species of bacteria. Much of niche expansion, resistance to antibiotics and other environmental stresses, virulence, and other characteristics that make bacteria interesting and problematic, is achieved through the expression of genes and genetic elements obtained from other populations of bacteria of the same and different species, as well as from eukaryotes and archaea. While recombination of homologous genes among members of the same species has played a central role in the development of the genetics and molecular biology of bacteria, the contribution of homologous gene recombination (HGR to bacterial evolution is not at all clear. Also, not so clear are the selective pressures responsible for the evolution and maintenance of transformation, the only bacteria-encoded form of HGR. Using a semi-stochastic simulation of mutation, recombination, and selection within bacterial populations and competition between populations, we explore (1 the contribution of HGR to the rate of adaptive evolution in these populations and (2 the conditions under which HGR will provide a bacterial population a selective advantage over non-recombining or more slowly recombining populations. The results of our simulation indicate that, under broad conditions: (1 HGR occurring at rates in the range anticipated for bacteria like Streptococcus pneumoniae, Escherichia coli, Haemophilus influenzae, and Bacillus subtilis will accelerate the rate at which a population adapts to environmental conditions; (2 once established in a population, selection for this capacity to increase rates of adaptive evolution can maintain bacteria-encoded mechanisms of recombination and prevent

  14. Los ferrocarriles de la República de Honduras

    Directory of Open Access Journals (Sweden)

    García, Marcela Alejandra

    1996-06-01

    Full Text Available Not available.

    El desarrollo ferroviario de Honduras respondió, ante todo, a las aspiraciones y necesidades del capital extranjero, fundamentalmente norteamericano. El descubrimiento del oro en California, primero, planteó el interés por abrir vías de comunicación en Centroamérica que comunicasen el Océano Atlántico y el Pacífico. La explotación del banano, después, implicó la explotación de una serie de líneas de ferrocarril que aseguraron el abastecimiento de este producto en el mercado norteamericano. La intención de este trabajo es mostrar la forma en que el desarrollo ferroviario hondureño dependió de las oscilaciones del negocio bananero. Como medio de transporte, adoleció prácticamente de efectos multiplicadores sobre el desarrollo económico y social del país, controlado por las empresas bananeras, concentradas en la región norte del país. Concluido el ciclo alcista de las economías exportadoras y, enfrentado a la competencia de nuevos medios de transporte y a la relativa diversificación económica de la segunda mitad del siglo XX en el marco del Mercado Común Centroamericano, se verá sumido en una crisis de carácter estructural que explica su lamentable estado actual.

  15. manejo de parques nacionales en Costa Rica, Honduras y Nicaragua

    Directory of Open Access Journals (Sweden)

    Juan Antonio Aguirre González

    2007-01-01

    Full Text Available El rápido crecimiento en él numero de nuevos visitantes, que se prevé ocurrirá en los parques nacionales de la América Central en los próximos años, hace necesario que los administradores de parques de la región consideren cada vez mas el nivel de satisfacción de los visitantes, por lo que se les ofrece a los visitantes en materia de infraestructura, servicios y opciones recreativas, en sus procesos de planificación y manejo de los parques. Un estudio basado en 915 encuestas, 312 a visitantes de origen local y 603 a visitantes de origen extranjero fue realizado en Honduras, Nicaragua y Costa Rica, con el fin de determinar la brecha en satisfacción de los visitantes con la infraestructura, los servicios y las opciones recreativas, utilizando una forma modificada del modelo de brecha basado en la teoría de las expectativas-desconfirmacion. El estudio encontró que había diferencias y semejanzas significativas al nivel de 95% de probabilidad entre las caracterizas socio-demográficas y los niveles de satisfacción de los visitantes locales y extranjeros a los diferentes parques y entre los visitantes locales y extranjeros en cada parque. Modelos estandarizados fueron identificados para cada parque en cada categoría de visitante los cuales permitieron identificar aquellas variables que más influenciaban la brecha en satisfacción. El material anterior permitió además identificar aquellas áreas más importantes a las cuales se les deberían asignar recursos financieros para mejorar en el corto plazo los niveles de satisfacción de los visitantes.

  16. Prefeasibility geothermal assessment of Platanares, Department of Copan, Honduras

    Energy Technology Data Exchange (ETDEWEB)

    Goff, S.; Goff, F.; Heiken, G.; Duffield, W.A.; Truesdell, A.H.; Laughlin, A.W.; Flores, W.

    1989-01-01

    The Platanares geothermal system is located in a region of active Quaternary tectonism in western Honduras. Although the geothermal area is partially blanketed by Miocene ignimbrites (14.5 m.y.), there are no nearby Quaternary volcanic rocks to act as a young magmatic heat source. No acid-sulfate waters, indicative of vapor-dominated conditions, exist in the area. Hot spring activity is most vigorous along a 2 km stretch of the Quebrada del Agua Caliente fault zone. Natural discharge is high (/approximately/3300 l/min), temperatures range from 35 to 100/degree/C, pH ranges from 7 to 9, and totally dissolved solids are low (/approximately/1100 mg/kg). Chemical geothermometers indicate a subsurface reservoir temperature of about 225/degree/C. Three exploration core holes (7.8 cm diameter) have been drilled to a maximum depth of 680 m and maximum temperature of 165/degree/C. Two holes produce copious amounts of water under artesian conditions (/approximately/500 l/min max; 5 bars flowing) from fractured red beds of Cretaceous to Eocene age (Valle de Angeles Group). Maximum power output is /approximately/4.5 MW (thermal) but CO/sub 2/ released during flashing formed some aragonite scale in one hole. The third core hole has an ''apparent'' conductive gradient of 139/degree/C/km at 400 m. Downward continuation of this gradient implies that the minimum depth to the geothermal resource (225/degree/C) is 1.5 to 2.0 km. 13 refs., 4 figs.

  17. Geology of the platanares geothermal area, Departamento de Copan, Honduras

    Science.gov (United States)

    Heiken, G.; Ramos, N.; Duffield, W.; Musgrave, J.; Wohletz, K.; Priest, S.; Aldrich, J.; Flores, W.; Ritchie, A.; Goff, F.; Eppler, D.; Escobar, C.

    1991-01-01

    Platanares is located 16 km west of Santa Rosa de Copan, Honduras, along the Quebrada del Agua Caliente. The thermal manifestations are along faults in tuffs, tuffaceous sedimentary rocks, and lavas of the Padre Miguel Group. These tuffs are silicified near the faults, are fractured, and may provide the fracture permeability necessary for the hydrothermal system. Tuffs are overlain by a wedge of terrace gravels up to 60 m thick. Quaternary conglomerates of the Quebrada del Agua Caliente are cemented by silica sinter. The Platanares area contains numerous faults, all of which appear to be extensional. There are four groups of faults (N80/sup 0/E to N70/sup 0/W, N30/sup 0/ to 60/sup 0/W, N40/sup 0/ to 65/sup 0/E, and N00/sup 0/ to 05/sup 0/W). All hot springs at this site are located along faults that trend mostly northwest and north. Twenty-eight spring groups were described over an area of 0.2 km/sup 2/; half were boiling. Based on surface temperatures and flow rates, between 0.7 and 1.0 MW thermal energy is estimated for the area. The increased temperature of the stream flowing through the thermal area indicates that several megawatts of thermal energy are being added to the stream. We recommend that a dipole-dipole resistivity line be run along the Quebrada del Agua Caliente to identify zones of fracture permeability associated with buried faults and hot water reservoirs within those fault zones. A thermal gradient corehole should be drilled at Platanares to test temperatures, lithologies, and permeability of the hydrothermal system.

  18. A geochemical model of the Platanares geothermal system, Honduras

    Science.gov (United States)

    Janik, C.J.; Truesdell, A.H.; Goff, F.; Shevenell, L.; Stallard, M.L.; Trujillo, P.E.; Counce, D.

    1991-01-01

    Results of exploration drilling combined with results of geologic, geophysical, and hydrogeochemical investigations have been used to construct a geochemical model of the Platanares geothermal system, Honduras. Three coreholes were drilled, two of which produced fluids from fractured Miocene andesite and altered Cretaceous to Eocene conglomerate at 450 to 680 m depth. Large volume artesian flows of 160-165??C, predominantly bicarbonate water are chemically similar to, but slightly less saline than widespread boiling hot-spring waters. The chemistry of the produced fluid is dominated by equilibrium reactions in sedimentary rocks at greater depths and higher temperatures than those measured in the wells. Chemical, isotope, and gas geothermometers indicate a deep fluid temperature of 200-245??C and reflect a relatively short residence time in the fractures feeding the wells. Chloride-enthalpy relations as well as isotopic and chemical compositions of well discharges, thermal springs, and local cold waters support a conceptual model of ascending high-temperature (minimum 225??C) parent fluid that has cooled conductively to form the 160-165??C shallow (to 680 m) fluid encountered by the wells. The hot-spring waters are formed by boiling and steam loss from more or less conductively cooled parent fluid. The more dilute boiling spring waters (Cl = ???32 mg/kg) have cooled from > 225??C to about 160??C by conduction and from 160??C to 98??C by boiling. The most concentrated boiling spring waters (Cl = 37 mg/kg) have cooled from > 225??C to about 200??C by conduction and from 200??C to 98??C by boiling. Intermediate concentrations reflect mixed cooling paths. ?? 1991.

  19. Postfire seedling dynamics and performance in Pinus halepensis Mill. populations

    Science.gov (United States)

    Daskalakou, Evangelia N.; Thanos, Costas A.

    2010-09-01

    Postfire dynamics of Aleppo pine seedling density, survival and growth were assessed in five burned forests of Attica, Greece (Stamata, Villia, Avlona, Kapandriti and Agios Stefanos) through the establishment of permanent experimental plots. All emerging seedlings were tagged and their survival and growth monitored at regular intervals. Seedling density dynamics show an initial, steep increase (to maximum values 2.9-4.6 seedlings m -2) followed by a gradual decrease that levels off at the second and third postfire year (1.3-3.0 seedlings m -2); similarly, postfire seedling survival more or less stabilised at 30-50%, 2-3 years after fire. On the basis of density and mortality trends as well as relevant bibliographic data, it is predicted that very dense, mature forests (10.000 trees ha -1 or more) will be reinstated within 15-20 years. During the first 5-7 postfire years, seedling/sapling annual height followed linear trends with various yearly rates, ranging mostly between 8 and 15 cm (and 27-30 cm in two exceptional, fast growing cases). Within an individual growth season, seedling height dynamics were found to follow sigmoid curves with growth increment peaks in mid-spring. The time (on a monthly basis) of seedling emergence did not affect seedling growth or survival. On the other hand, for the first time under natural conditions, it has been shown that cotyledon number per seedling, an indirect measure of both seed size and initial photosynthetic capacity, significantly affected seedling survival but not growth. Seedlings bearing a higher number of cotyledons, presumably derived from larger seeds, showed greater survival at the end of the first postfire year than seedlings with fewer cotyledons. A postfire selective pressure, favouring large seed size, is postulated to counteract with a contrasting one, which favours small seed size, expressed during fire-free conditions.

  20. Dynamics of climate-based malaria transmission model with age-structured human population

    Science.gov (United States)

    Addawe, Joel; Pajimola, Aprimelle Kris

    2016-10-01

    In this paper, we proposed to study the dynamics of malaria transmission with periodic birth rate of the vector and an age-structure for the human population. The human population is divided into two compartments: pre-school (0-5 years) and the rest of the human population. We showed the existence of a disease-free equilibrium point. Using published epidemiological parameters, we use numerical simulations to show potential effect of climate change in the dynamics of age-structured malaria transmission. Numerical simulations suggest that there exists an asymptotically attractive solution that is positive and periodic.

  1. Employment-generating projects for the energy and minerals sectors of Honduras. Proyectos generadores de empleos para los sectores energetico y minero de Honduras

    Energy Technology Data Exchange (ETDEWEB)

    Frank, J.A.

    1988-12-01

    A mission to Honduras invited by the Government of Honduras and sponsored by the Organization of American States addressed the generation of employment in various areas of interest to the country. The mission was made up of experts from numerous countries and international agencies. In the energy sector, the mission recommended consolidating the sector under a coordinating body; carrying out projects to promote reforestation, tree farms, and rational forest utilization; encouraging industrial energy conservation; developing alternative energy sources; and promoting rural electrification and expansion of the electrical grid. In the mining sector, the mission supported promotion and technical assistance for small gold-leaching and placer operations, the national mineral inventory, detailed exploration of promising sites, and the development of a mining school. 13 refs., 7 tabs.

  2. Potential impact of harvesting on the population dynamics of two epiphytic bromeliads

    Science.gov (United States)

    Toledo-Aceves, Tarin; Hernández-Apolinar, Mariana; Valverde, Teresa

    2014-08-01

    Large numbers of epiphytes are extracted from cloud forests for ornamental use and illegal trade in Latin America. We examined the potential effects of different harvesting regimes on the population dynamics of the epiphytic bromeliads Tillandsia multicaulis and Tillandsia punctulata. The population dynamics of these species were studied over a 2-year period in a tropical montane cloud forest in Veracruz, Mexico. Prospective and retrospective analyses were used to identify which demographic processes and life-cycle stages make the largest relative contribution to variation in population growth rate (λ). The effect of simulated harvesting levels on population growth rates was analysed for both species. λ of both populations was highly influenced by survival (stasis), to a lesser extent by growth, and only slightly by fecundity. Vegetative growth played a central role in the population dynamics of these organisms. The λ value of the studied populations did not differ significantly from unity: T. multicaulis λ (95% confidence interval) = 0.982 (0.897-1.060) and T. punctulata λ = 0.967 (0.815-1.051), suggesting population stability. However, numerical simulation of different levels of extraction showed that λ would drop substantially even under very low (2%) harvesting levels. Matrix analysis revealed that T. multicaulis and T. punctulata populations are likely to decline and therefore commercial harvesting would be unsustainable. Based on these findings, management recommendations are outlined.

  3. Evolutionary dynamics of the most populated genotype on rugged fitness landscapes

    Science.gov (United States)

    Jain, Kavita

    2007-09-01

    We consider an asexual population evolving on rugged fitness landscapes which are defined on the multidimensional genotypic space and have many local optima. We track the most populated genotype as it changes when the population jumps from a fitness peak to a better one during the process of adaptation. This is done using the dynamics of the shell model which is a simplified version of the quasispecies model for infinite populations and standard Wright-Fisher dynamics for large finite populations. We show that the population fraction of a genotype obtained within the quasispecies model and the shell model match for fit genotypes and at short times, but the dynamics of the two models are identical for questions related to the most populated genotype. We calculate exactly several properties of the jumps in infinite populations, some of which were obtained numerically in previous works. We also present our preliminary simulation results for finite populations. In particular, we measure the jump distribution in time and find that it decays as t-2 as in the quasispecies problem.

  4. Do resources or natural enemies drive bee population dynamics in fragmented habitats?

    Science.gov (United States)

    Steffan-Dewenter, Ingolf; Schiele, Susanne

    2008-05-01

    The relative importance of bottom-up or top-down forces has been mainly studied for herbivores but rarely for pollinators. Habitat fragmentation might change driving forces of population dynamics by reducing the area of resource-providing habitats, disrupting habitat connectivity, and affecting natural enemies more than their host species. We studied spatial and temporal population dynamics of the solitary bee Osmia rufa (Hymenoptera: Megachilidae) in 30 fragmented orchard meadows ranging in size from 0.08 to 5.8 ha in an agricultural landscape in central Germany. From 1998 to 2003, we monitored local bee population size, rate of parasitism, and rate of larval and pupal mortality in reed trap nests as an accessible and standardized nesting resource. Experimentally enhanced nest site availability resulted in a steady increase of mean local population size from 80 to 2740 brood cells between 1998 and 2002. Population size and species richness of natural enemies increased with habitat area, whereas rate of parasitism and mortality only varied among years. Inverse density-dependent parasitism in three study years with highest population size suggests rather destabilizing instead of regulating effects of top-down forces. Accordingly, an analysis of independent time series showed on average a negative impact of population size on population growth rates but provides no support for top-down regulation by natural enemies. We conclude that population dynamics of O. rufa are mainly driven by bottom-up forces, primarily nest site availability.

  5. Reproductive success is predicted by social dynamics and kinship in managed animal populations.

    Science.gov (United States)

    Newman, Saul J; Eyre, Simon; Kimble, Catherine H; Arcos-Burgos, Mauricio; Hogg, Carolyn; Easteal, Simon

    2016-01-01

    Kin and group interactions are important determinants of reproductive success in many species. Their optimization could, therefore, potentially improve the productivity and breeding success of managed populations used for agricultural and conservation purposes. Here we demonstrate this potential using a novel approach to measure and predict the effect of kin and group dynamics on reproductive output in a well-known species, the meerkat Suricata suricatta. Variation in social dynamics predicts 30% of the individual variation in reproductive success of this species in managed populations, and accurately forecasts reproductive output at least two years into the future. Optimization of social dynamics in captive meerkat populations doubles their projected reproductive output. These results demonstrate the utility of a quantitative approach to breeding programs informed by social and kinship dynamics. They suggest that this approach has great potential for improvements in the management of social endangered and agricultural species.

  6. The basic approach to age-structured population dynamics models, methods and numerics

    CERN Document Server

    Iannelli, Mimmo

    2017-01-01

    This book provides an introduction to age-structured population modeling which emphasises the connection between mathematical theory and underlying biological assumptions. Through the rigorous development of the linear theory and the nonlinear theory alongside numerics, the authors explore classical equations that describe the dynamics of certain ecological systems. Modeling aspects are discussed to show how relevant problems in the fields of demography, ecology, and epidemiology can be formulated and treated within the theory. In particular, the book presents extensions of age-structured modelling to the spread of diseases and epidemics while also addressing the issue of regularity of solutions, the asymptotic behaviour of solutions, and numerical approximation. With sections on transmission models, non-autonomous models and global dynamics, this book fills a gap in the literature on theoretical population dynamics. The Basic Approach to Age-Structured Population Dynamics will appeal to graduate students an...

  7. Population synthesis of planet formation using a torque formula with dynamic effects

    CERN Document Server

    Sasaki, Takanori

    2016-01-01

    Population synthesis studies into planet formation have suggested that distributions consistent with observations can only be reproduced if the actual Type I migration timescale is at least an order of magnitude longer than that deduced from linear theories. Although past studies considered the effect of the Type I migration of protoplanetary embryos, in most cases they used a conventional formula based on static torques in isothermal disks, and employed a reduction factor to account for uncertainty in the mechanism details. However, in addition to static torques, a migrating planet experiences dynamic torques that are proportional to the migration rate. These dynamic torques can impact on planet migration and predicted planetary populations. In this study, we derived a new torque formula for Type I migration by taking into account dynamic corrections. This formula was used to perform population synthesis simulations with and without the effect of dynamic torques. In many cases, inward migration was slowed si...

  8. Population-reaction model and microbial experimental ecosystems for understanding hierarchical dynamics of ecosystems.

    Science.gov (United States)

    Hosoda, Kazufumi; Tsuda, Soichiro; Kadowaki, Kohmei; Nakamura, Yutaka; Nakano, Tadashi; Ishii, Kojiro

    2016-02-01

    Understanding ecosystem dynamics is crucial as contemporary human societies face ecosystem degradation. One of the challenges that needs to be recognized is the complex hierarchical dynamics. Conventional dynamic models in ecology often represent only the population level and have yet to include the dynamics of the sub-organism level, which makes an ecosystem a complex adaptive system that shows characteristic behaviors such as resilience and regime shifts. The neglect of the sub-organism level in the conventional dynamic models would be because integrating multiple hierarchical levels makes the models unnecessarily complex unless supporting experimental data are present. Now that large amounts of molecular and ecological data are increasingly accessible in microbial experimental ecosystems, it is worthwhile to tackle the questions of their complex hierarchical dynamics. Here, we propose an approach that combines microbial experimental ecosystems and a hierarchical dynamic model named population-reaction model. We present a simple microbial experimental ecosystem as an example and show how the system can be analyzed by a population-reaction model. We also show that population-reaction models can be applied to various ecological concepts, such as predator-prey interactions, climate change, evolution, and stability of diversity. Our approach will reveal a path to the general understanding of various ecosystems and organisms. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  9. Role of seasonality on predator-prey-subsidy population dynamics.

    Science.gov (United States)

    Levy, Dorian; Harrington, Heather A; Van Gorder, Robert A

    2016-05-07

    The role of seasonality on predator-prey interactions in the presence of a resource subsidy is examined using a system of non-autonomous ordinary differential equations (ODEs). The problem is motivated by the Arctic, inhabited by the ecological system of arctic foxes (predator), lemmings (prey), and seal carrion (subsidy). We construct two nonlinear, nonautonomous systems of ODEs named the Primary Model, and the n-Patch Model. The Primary Model considers spatial factors implicitly, and the n-Patch Model considers space explicitly as a "Stepping Stone" system. We establish the boundedness of the dynamics, as well as the necessity of sufficiently nutritional food for the survival of the predator. We investigate the importance of including the resource subsidy explicitly in the model, and the importance of accounting for predator mortality during migration. We find a variety of non-equilibrium dynamics for both systems, obtaining both limit cycles and chaotic oscillations. We were then able to discuss relevant implications for biologically interesting predator-prey systems including subsidy under seasonal effects. Notably, we can observe the extinction or persistence of a species when the corresponding autonomous system might predict the opposite.

  10. Trypanosoma cruzi population dynamics in the Central Ecuadorian Coast.

    Science.gov (United States)

    Costales, Jaime A; Jara-Palacios, Miguel A; Llewellyn, Martin S; Messenger, Louisa A; Ocaña-Mayorga, Sofía; Villacís, Anita G; Tibayrenc, Michel; Grijalva, Mario J

    2015-11-01

    Chagas disease is the most important parasitic disease in Latin America. The causative agent, Trypanosoma cruzi, displays high genetic diversity and circulates in complex transmission cycles among domestic, peridomestic and sylvatic environments. In Ecuador, Rhodnius ecuadoriensis is known to be the major vector species implicated in T. cruzi transmission. However, across vast areas of Ecuador, little is known about T. cruzi genetic diversity in relation to different parasite transmission scenarios. Fifty-eight T. cruzi stocks from the central Ecuadorian coast, most of them derived from R. ecuadoriensis, were included in the study. All of them were genotyped as T. cruzi discrete typing unit I (DTU TcI). Analysis of 23 polymorphic microsatellite loci through neighbor joining and discriminant analysis of principal components yielded broadly congruent results and indicate genetic subdivision between sylvatic and peridomestic transmission cycles. However, both analyses also suggest that any barriers are imperfect and significant gene flow between parasite subpopulations in different habitats exists. Also consistent with moderate partition and residual gene flow between subpopulations, the fixation index (FST) was significant, but of low magnitude. Finally, the lack of private alleles in the domestic/peridomestic transmission cycle suggests the sylvatic strains constitute the ancestral population. The T. cruzi population in the central Ecuadorian coast shows moderate tendency to subdivision according to transmission cycle. However, connectivity between cycles exists and the sylvatic T. cruzi population harbored by R. ecuadoriensis vectors appears to constitute a source from which the parasite invades human domiciles and their surroundings in this region. We discuss the implications these findings have for the planning, implementation and evaluation of local Chagas disease control interventions.

  11. Population dynamics of spotted owls in the Sierra Nevada, California

    Science.gov (United States)

    Blakesley, J.A.; Seamans, M.E.; Conner, M.M.; Franklin, A.B.; White, Gary C.; Gutierrez, R.J.; Hines, J.E.; Nichols, J.D.; Munton, T.E.; Shaw, D.W.H.; Keane, J.J.; Steger, G.N.; McDonald, T.L.

    2010-01-01

    The California spotted owl (Strix occidentalis occidentalis) is the only spotted owl subspecies not listed as threatened or endangered under the United States Endangered Species Act despite petitions to list it as threatened. We conducted a meta-analysis of population data for 4 populations in the southern Cascades and Sierra Nevada, California, USA, from 1990 to 2005 to assist a listing evaluation by the United States Fish and Wildlife Service. Our study areas (from N to S) were on the Lassen National Forest (LAS), Eldorado National Forest (ELD), Sierra National Forest (SIE), and Sequoia and Kings Canyon National Parks (SKC). These study areas represented a broad spectrum of habitat and management conditions in these mountain ranges. We estimated apparent survival probability, reproductive output, and rate of population change for spotted owls on individual study areas and for all study areas combined (meta-analysis) using model selection or model-averaging based on maximum-likelihood estimation. We followed a formal protocol to conduct this analysis that was similar to other spotted owl meta-analyses. Consistency of field and analytical methods among our studies reduced confounding methodological effects when evaluating results. We used 991 marked spotted owls in the analysis of apparent survival. Apparent survival probability was higher for adult than for subadult owls. There was little difference in apparent survival between male and female owls. Model-averaged mean estimates of apparent survival probability of adult owls varied from 0.811 ?? 0.021 for females at LAS to 0.890 ?? 0.016 for males at SKC. Apparent survival increased over time for owls of all age classes at LAS and SIE, for adults at ELD, and for second-year subadults and adults at SKC. The meta-analysis of apparent survival, which included only adult owls, confirmed an increasing trend in survival over time. Survival rates were higher for owls on SKC than on the other study areas. We analyzed data

  12. Reinforcement learning in complementarity game and population dynamics.

    Science.gov (United States)

    Jost, Jürgen; Li, Wei

    2014-02-01

    We systematically test and compare different reinforcement learning schemes in a complementarity game [J. Jost and W. Li, Physica A 345, 245 (2005)] played between members of two populations. More precisely, we study the Roth-Erev, Bush-Mosteller, and SoftMax reinforcement learning schemes. A modified version of Roth-Erev with a power exponent of 1.5, as opposed to 1 in the standard version, performs best. We also compare these reinforcement learning strategies with evolutionary schemes. This gives insight into aspects like the issue of quick adaptation as opposed to systematic exploration or the role of learning rates.

  13. Climate Effects and Feedback Structure Determining Weed Population Dynamics in a Long-Term Experiment

    Science.gov (United States)

    Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

    2012-01-01

    Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements. PMID:22272362

  14. Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

    Science.gov (United States)

    Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

    2012-01-01

    Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

  15. Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

    Directory of Open Access Journals (Sweden)

    Mauricio Lima

    Full Text Available Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors. Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

  16. Associations between seasonal influenza and meteorological parameters in Costa Rica, Honduras and Nicaragua.

    Science.gov (United States)

    Soebiyanto, Radina P; Clara, Wilfrido A; Jara, Jorge; Balmaseda, Angel; Lara, Jenny; Lopez Moya, Mariel; Palekar, Rakhee; Widdowson, Marc-Alain; Azziz-Baumgartner, Eduardo; Kiang, Richard K

    2015-11-04

    Seasonal influenza affects a considerable proportion of the global population each year. We assessed the association between subnational influenza activity and temperature, specific humidity and rainfall in three Central America countries, i.e. Costa Rica, Honduras and Nicaragua. Using virologic data from each country's national influenza centre, rainfall from the Tropical Rainfall Measuring Mission and air temperature and specific humidity data from the Global Land Data Assimilation System, we applied logistic regression methods for each of the five sub-national locations studied. Influenza activity was represented by the weekly proportion of respiratory specimens that tested positive for influenza. The models were adjusted for the potentially confounding co-circulating respiratory viruses, seasonality and previous weeks' influenza activity. We found that influenza activity was proportionally associated (P<0.05) with specific humidity in all locations [odds ratio (OR) 1.21-1.56 per g/kg], while associations with temperature (OR 0.69-0.81 per °C) and rainfall (OR 1.01-1.06 per mm/day) were location-dependent. Among the meteorological parameters, specific humidity had the highest contribution (~3-15%) to the model in all but one location. As model validation, we estimated influenza activity for periods, in which the data was not used in training the models. The correlation coefficients between the estimates and the observed were ≤0.1 in 2 locations and between 0.6-0.86 in three others. In conclusion, our study revealed a proportional association between influenza activity and specific humidity in selected areas from the three Central America countries.

  17. Dynamics of chemically stressed populations: the deduction of population consequences from effects on individuals

    Energy Technology Data Exchange (ETDEWEB)

    Kooijman, S.A.; Metz, J.A.

    1984-06-01

    A general, simple, and explicit model for the age-dependent growth and reproduction of individuals as a function of food supply is presented. The model assumes a Holling-type functional response coupled with a von Bertalanffy body growth law, a fixed ratio between the energy utilized for reproduction and respiration, and a juvenile stage that ends as soon as the animal attains a sufficient weight. This model is shown to fit the available data on the development of Daphnia magna quite well. The model is used as a basis for studying the effects of chemicals on population growth rate, given the effects on individuals. Effects on individual growth and reproduction are reflected in a concentration-dependent relative reduction of the population growth rate. Effects on feeding rate, digestion, basal metabolism, and survival work out much more dramatically at low natural population growth rates. This already follows from a much simpler model that assumes age-independent reproduction, as exemplified to a good approximation by the rotifer Brachionus rubens. The theoretical results are supplemented with experimental evidence, implying that the stress on a population at a certain concentration of a chemical may indeed be strongly dependent on the feeding state of that population.

  18. Effects of infection on honey bee population dynamics: a model.

    Directory of Open Access Journals (Sweden)

    Matt I Betti

    Full Text Available We propose a model that combines the dynamics of the spread of disease within a bee colony with the underlying demographic dynamics of the colony to determine the ultimate fate of the colony under different scenarios. The model suggests that key factors in the survival or collapse of a honey bee colony in the face of an infection are the rate of transmission of the infection and the disease-induced death rate. An increase in the disease-induced death rate, which can be thought of as an increase in the severity of the disease, may actually help the colony overcome the disease and survive through winter. By contrast, an increase in the transmission rate, which means that bees are being infected at an earlier age, has a drastic deleterious effect. Another important finding relates to the timing of infection in relation to the onset of winter, indicating that in a time interval of approximately 20 days before the onset of winter the colony is most affected by the onset of infection. The results suggest further that the age of recruitment of hive bees to foraging duties is a good early marker for the survival or collapse of a honey bee colony in the face of infection, which is consistent with experimental evidence but the model provides insight into the underlying mechanisms. The most important result of the study is a clear distinction between an exposure of the honey bee colony to an environmental hazard such as pesticides or insecticides, or an exposure to an infectious disease. The results indicate unequivocally that in the scenarios that we have examined, and perhaps more generally, an infectious disease is far more hazardous to the survival of a bee colony than an environmental hazard that causes an equal death rate in foraging bees.

  19. Linking animal population dynamics to alterations in foraging behaviour

    DEFF Research Database (Denmark)

    Nabe-Nielsen, Jacob; Sibly, Richard; Tougaard, Jakob;

    was not jeopardized even when disturbances were simulated to have a relatively large and persistent effect on the behavior of individual animals. Porpoises were simulated to move away from noisy objects, preventing them from returning to the known food patches in that area. This resulted in decreasing energy reserves...... to disturbances by moving away are prevented from accessing the food in the disturbed areas and may also be prevented from dispersing among areas where food is available at different times of the year. Such disturbance effects may play a particularly large role for marine mammals that live in environments...... realistic movement patterns in scenarios where animals were not exposed to noise. Results/Conclusions The main results of the study were that the effects of disturbances were highly dependent on how fast the food recovered after being eaten, but that the long-term survival of the population...

  20. Reinforcement learning in complementarity game and population dynamics

    Science.gov (United States)

    Jost, Jürgen; Li, Wei

    2014-02-01

    We systematically test and compare different reinforcement learning schemes in a complementarity game [J. Jost and W. Li, Physica A 345, 245 (2005), 10.1016/j.physa.2004.07.005] played between members of two populations. More precisely, we study the Roth-Erev, Bush-Mosteller, and SoftMax reinforcement learning schemes. A modified version of Roth-Erev with a power exponent of 1.5, as opposed to 1 in the standard version, performs best. We also compare these reinforcement learning strategies with evolutionary schemes. This gives insight into aspects like the issue of quick adaptation as opposed to systematic exploration or the role of learning rates.

  1. Population dynamics of the Kaminuriak caribou herd, 1968 - 1985

    Directory of Open Access Journals (Sweden)

    Douglas C. Heard

    1986-06-01

    Full Text Available The Kaminuraik caribou herd apparently declined from about 120 000 animals in 1950 to 63 000 in 1968. Beginning in 1968 documentation of herd trend was based on the estimate of the number of breeding (pregnant and post-partum females on the calving ground during the birth peak. It appeared as if we understood the basic population processes responsible for the decline when we correctly predicted a drop from 14 800 breeding females in 1977 to 13 000 in 1980. However a three-fold increase, to 41 000 breeding females in 1982, and continued growth thereafter, was unanticipated. Most of that increase must have resulted from an immigration of cows to the herd's traditional calving ground around Kaminuriak Lake, although increased birth rates, and increased survival rates also contributed to herd growth. Immigrant cows probably came from the northeastern mainland of the NWT

  2. 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....... The population projection models accurately captured observed fluctuations in population size. Our analyses suggested the population was intrinsically regulated but with annual fluctuations in response to variation in weather. Simulations showed that implicitly assuming variation in demographic rates...

  3. Patient and provider population dynamics analysis in a large dental organization: a tool for management.

    Science.gov (United States)

    Patterson, Charles W

    2010-12-01

    Health care managers are faced with difficult decisions on a daily basis. Some of those issues involve productivity. Statistical analyses of patient and provider population dynamics offer an important tool with which to base decisions. In this study, two representative clinics out of seven were selected. The patient and provider populations were subjected to the means square successive difference test and a linear regression test. The results differed from management perceptions. Provider decision processes in clinic A were more efficient than those in clinic B. There was no relationship between provider presence and the patient population in both clinics. The patient populations in both clinics displayed random arrivals. Specific recommendations to management from the results of this study include: billeting decisions, appointing process decisions, emergency policies, and the need for a focused marketing plan. There are many useful tools with which to study population dynamics. This is one example.

  4. Population Dynamics and Ecology of Arcobacter in Sewage

    Directory of Open Access Journals (Sweden)

    Jenny C Fisher

    2014-11-01

    Full Text Available Arcobacter species are highly abundant in sewage where they often comprise approximately 5-11% of the bacterial community. Oligotyping of sequences amplified from the V4V5 region of the 16S rRNA gene revealed Arcobacter populations from different cities were similar and dominated by one to three members, with extremely high microdiversity in the minor members. Overall, nine subgroups within the Arcobacter genus accounted for >80% of the total Arcobacter sequences in all samples analyzed. The distribution of oligotypes varied by both sample site and temperature, with samples from the same site generally being more similar to each other than other sites. Seven oligotypes matched with 100% identity to characterized Arcobacter species, but the remaining 19 abundant oligotypes appear to be unknown species. Sequences representing the two most abundant oligotypes matched exactly to the type strains for A. cryaerophilus group 1B (CCUG 17802 and group 1A (CCUG17801, respectively. Oligotype 1 showed generally lower relative abundance in colder samples and higher relative abundance in warmer samples; the converse was true for Oligotype 2. Ten other oligotypes had significant positive or negative correlations between temperature and proportion in samples as well. The oligotype that corresponded to A. butzleri, the Arcobacter species most commonly isolated by culturing in sewage studies, was only the eleventh most abundant oligotype. This work suggests that Arcobacter populations occupy unique niches in sewer infrastructure and are modulated by temperature. Furthermore, current culturing methods used for identification of Arcobacter fail to identify some abundant members of the community and may underestimate the presence of species with affinities for growth at lower temperatures. Understanding the ecological factors that affect the survival and growth of Arcobacter spp. in sewer infrastructure may better inform the risks associated with these emerging

  5. Crisis Discourses and Technology Regulation in a Weak State: Response to a Pesticide Disaster in Honduras

    NARCIS (Netherlands)

    Jansen, K.

    2003-01-01

    Hurricane Mitch hit Honduras in October 1998, leaving a trail of death, injury and devastating damage. As it tore through the country, the hurricane damaged a number of warehouses which contained pesticides, resulting in the discharge of more than 70 tonnes of pesticides into the environment. This a

  6. Opening the Black Box: Women's Empowerment and Innovative Secondary Education in Honduras

    Science.gov (United States)

    Murphy-Graham, Erin

    2008-01-01

    This article aims to clarify the relationship between education and women's empowerment. Drawing from qualitative data collected in a study of four Garifuna villages on the north coast of Honduras, it argues that education can trigger the empowerment process if it expands women's knowledge and understanding, self-confidence and awareness of gender…

  7. First report of 'Candidatus Liberibacter solanacearum' associated with psylllid-affected tobacco in Honduras

    Science.gov (United States)

    Tobacco plants with symptoms resembling those associated with the psyllid Bactericera cockerelli and the bacterium “Candidatus Liberibacter solanacearum” (Lso) were observed in April of 2012 in heavily B. cockerelli-infested commercial fields in the Department of El-Paraíso, Honduras; all cultivars ...

  8. First report of Dolabra nepheliae associated with corky bark disease of Rambutan and Pulasan in Honduras

    Science.gov (United States)

    Rambutan (Nephelium lappaceum L., Sapindaceae) was first introduced into Honduras in 1927 but commercial production was not started until after 1980 when cultivation of pulasan (N. mutabile Blume) was initiated. In the last decade these crops have become popular as exotic fruit for export to North A...

  9. Cultural Capital and Innovative Pedagogy: A Case Study among Indigenous Communities in Mexico and Honduras

    Science.gov (United States)

    Gregorcic, Marta

    2009-01-01

    This article introduces case studies of innovative approaches to pedagogy among indigenous Mayan communities in Chiapas (Mexico) and Lencan communities in Intibuca (Honduras). Innovative approaches to researching alternative theories and practices of pedagogy are used by the author to develop an epistemology of critical pedagogy and its potential…

  10. Quality and Efficiency in a Complementary Middle School Program: The "Educatodos" Experience in Honduras

    Science.gov (United States)

    Marshall, Jeffery H.; Mejia R., Marco Tulio; Aguilar, Claudia R.

    2008-01-01

    In this article, the authors use recently collected data from the "Educatodos" program in Honduras to analyze attrition, an outcome that has received little attention in previous analyses of alternative school effectiveness. "Educatodos" began in the 1990s with radio courses in primary grades mainly for rural adults. Through…

  11. Opening the Black Box: Women's Empowerment and Innovative Secondary Education in Honduras

    Science.gov (United States)

    Murphy-Graham, Erin

    2008-01-01

    This article aims to clarify the relationship between education and women's empowerment. Drawing from qualitative data collected in a study of four Garifuna villages on the north coast of Honduras, it argues that education can trigger the empowerment process if it expands women's knowledge and understanding, self-confidence and awareness of gender…

  12. Using "EC-Assess" to Assess a Small Biofuels Project in Honduras

    Science.gov (United States)

    Ngassa, Franklin Chamda

    2010-01-01

    Biofuels may contribute to both rural economic development and climate change mitigation and adaptation. The Gota Verde Project in Yoro, Honduras, attempts to demonstrate the technical and economic feasibility of small-scale biofuel production for local use by implementing a distinctive approach to feedstock production that encourages small farm…

  13. Decentralization and Educational Performance: Evidence from the PROHECO Community School Program in Rural Honduras

    Science.gov (United States)

    Di Gropello, Emanuela; Marshall, Jeffery H.

    2011-01-01

    We analyze the effectiveness of the Programa Hondureno de Educacion Comunitaria (PROHECO) community school program in rural Honduras. The data include standardized tests and extensive information on school, teacher, classroom and community features for 120 rural schools drawn from 15 states. Using academic achievement decompositions we find that…

  14. How Patronage Politics Undermines Parental Participation and Accountability: Community-Managed Schools in Honduras and Guatemala

    Science.gov (United States)

    Altschuler, Daniel

    2013-01-01

    This article shows how patronage politics affects a popular international education model: community-managed schools (CMS). Focusing on Honduras's CMS initiative, PROHECO (Programa Hondureno de Educacion Comunitaria), I demonstrate how patronage can undermine CMS accountability. Whereas supporters argue that CMS increases accountability, partisan…

  15. Decentralization and Educational Performance: Evidence from the PROHECO Community School Program in Rural Honduras

    Science.gov (United States)

    Di Gropello, Emanuela; Marshall, Jeffery H.

    2011-01-01

    We analyze the effectiveness of the Programa Hondureno de Educacion Comunitaria (PROHECO) community school program in rural Honduras. The data include standardized tests and extensive information on school, teacher, classroom and community features for 120 rural schools drawn from 15 states. Using academic achievement decompositions we find that…

  16. How Patronage Politics Undermines Parental Participation and Accountability: Community-Managed Schools in Honduras and Guatemala

    Science.gov (United States)

    Altschuler, Daniel

    2013-01-01

    This article shows how patronage politics affects a popular international education model: community-managed schools (CMS). Focusing on Honduras's CMS initiative, PROHECO (Programa Hondureno de Educacion Comunitaria), I demonstrate how patronage can undermine CMS accountability. Whereas supporters argue that CMS increases accountability, partisan…

  17. Using "EC-Assess" to Assess a Small Biofuels Project in Honduras

    Science.gov (United States)

    Ngassa, Franklin Chamda

    2010-01-01

    Biofuels may contribute to both rural economic development and climate change mitigation and adaptation. The Gota Verde Project in Yoro, Honduras, attempts to demonstrate the technical and economic feasibility of small-scale biofuel production for local use by implementing a distinctive approach to feedstock production that encourages small farm…

  18. Creating Sustainable Education Projects in Roatán, Honduras through Continuous Process Improvement

    Science.gov (United States)

    Raven, Arjan; Randolph, Adriane B.; Heil, Shelli

    2010-01-01

    The investigators worked together with permanent residents of Roatán, Honduras on sustainable initiatives to help improve the island's troubled educational programs. Our initiatives focused on increasing the number of students eligible and likely to attend a university. Using a methodology based in continuous process improvement, we developed…

  19. La Persistencia de la Pobreza Rural en Honduras, Nicaragua y Bolivia: un Fracaso del Neoliberalismo

    NARCIS (Netherlands)

    C. Kay (Cristóbal)

    2009-01-01

    textabstractLos documentos de estrategia de lucha contra la pobreza, preparados por los gobiernos mediante un proceso en el que participan instituciones internacionales y actores de la sociedad civil, no dieron los resultados previstos. El artículo analiza los casos de Honduras, Nicaragua y Bolivia

  20. Policies for sustainable development in the hillside areas of Honduras: a quantitative livelihoods approach

    NARCIS (Netherlands)

    Jansen, H.P.G.; Pender, J.; Damon, A.; Wielemaker, W.; Schipper, R.A.

    2006-01-01

    In this article, we use data for 376 households, 1,066 parcels, and 2,143 plots located in 95 villages in the hillside areas in Honduras to generate information needed by decision makers to assess the needs and opportunities for public investments, and design policies that stimulate natural resource

  1. La Persistencia de la Pobreza Rural en Honduras, Nicaragua y Bolivia: un Fracaso del Neoliberalismo

    NARCIS (Netherlands)

    C. Kay (Cristóbal)

    2009-01-01

    textabstractLos documentos de estrategia de lucha contra la pobreza, preparados por los gobiernos mediante un proceso en el que participan instituciones internacionales y actores de la sociedad civil, no dieron los resultados previstos. El artículo analiza los casos de Honduras, Nicaragua y Bolivia

  2. Crisis Discourses and Technology Regulation in a Weak State: Response to a Pesticide Disaster in Honduras

    NARCIS (Netherlands)

    Jansen, K.

    2003-01-01

    Hurricane Mitch hit Honduras in October 1998, leaving a trail of death, injury and devastating damage. As it tore through the country, the hurricane damaged a number of warehouses which contained pesticides, resulting in the discharge of more than 70 tonnes of pesticides into the environment. This a

  3. Crisis Discourses and Technology Regulation in a Weak State: Response to a Pesticide Disaster in Honduras

    NARCIS (Netherlands)

    Jansen, K.

    2003-01-01

    Hurricane Mitch hit Honduras in October 1998, leaving a trail of death, injury and devastating damage. As it tore through the country, the hurricane damaged a number of warehouses which contained pesticides, resulting in the discharge of more than 70 tonnes of pesticides into the environment. This

  4. A Faculty Short Course on Improving College Teaching at Escuela Agricola Panamericana, Tegucigalpa, Honduras, Central America.

    Science.gov (United States)

    Cheek, Jimmy G.; Beeman, Carl E.

    A short course on improving college teaching at Escuela Agricola Panamericana (EAP), in Tegucigalpa, Honduras, is discussed. Two University of Florida college faculty members were engaged by the United States Information Agency to conduct the 2-week course for EAP college faculty. Course objectives included: identifying the role of the teacher and…

  5. A Faculty Short Course on Improving College Teaching at Escuela Agricola Panamericana, Tegucigalpa, Honduras, Central America.

    Science.gov (United States)

    Cheek, Jimmy G.; Beeman, Carl E.

    A short course on improving college teaching at Escuela Agricola Panamericana (EAP), in Tegucigalpa, Honduras, is discussed. Two University of Florida college faculty members were engaged by the United States Information Agency to conduct the 2-week course for EAP college faculty. Course objectives included: identifying the role of the teacher and…

  6. Spatially explicit modeling of habitat dynamics and fish population persistence in an intermittent lowland stream.

    Science.gov (United States)

    Perry, George L W; Bond, Nicholas R

    2009-04-01

    In temperate and arid climate zones many streams and rivers flow intermittently, seasonally contracting to a sequence of isolated pools or waterholes over the dry period, before reconnecting in the wetter parts of the year. This seasonal drying process is central to our understanding of the population dynamics of aquatic organisms such as fish and invertebrates in these systems. However, there is a dearth of empirical data on the temporal dynamics of such populations. We describe a spatially explicit individual-based model (SEIBM) of fish population dynamics in such systems, which we use to explore the long-term population viability of the carp gudgeon Hypseleotris spp. in a lowland stream in southeastern Australia. We explicitly consider the impacts of interannual variability in stream flow, for example, due to drought, on habitat availability and hence population persistence. Our results support observations that these populations are naturally highly variable, with simulated fish population sizes typically varying over four orders of magnitude within a 50-year simulation run. The most sensitive parameters in the model relate to the amount of water (habitat) in the system: annual rainfall, seepage loss from the pools, and the carrying capacity (number of individuals per cubic meter) of the pools as they dry down. It seems likely that temporal source sink dynamics allow the fish populations to persist in these systems, with good years (high rainfall and brief cease-to-flow [CTF] periods) buffering against periods of drought. In dry years during which the stream may contract to very low numbers of pools, each of these persistent pools becomes crucial for the persistence of the population in the system. Climate change projections for this area suggest decreases in rainfall and increased incidence of drought; under these environmental conditions the long-term persistence of these fish populations is uncertain.

  7. A Theoretical Approach to Understanding Population Dynamics with Seasonal Developmental Durations

    Science.gov (United States)

    Lou, Yijun; Zhao, Xiao-Qiang

    2017-04-01

    There is a growing body of biological investigations to understand impacts of seasonally changing environmental conditions on population dynamics in various research fields such as single population growth and disease transmission. On the other side, understanding the population dynamics subject to seasonally changing weather conditions plays a fundamental role in predicting the trends of population patterns and disease transmission risks under the scenarios of climate change. With the host-macroparasite interaction as a motivating example, we propose a synthesized approach for investigating the population dynamics subject to seasonal environmental variations from theoretical point of view, where the model development, basic reproduction ratio formulation and computation, and rigorous mathematical analysis are involved. The resultant model with periodic delay presents a novel term related to the rate of change of the developmental duration, bringing new challenges to dynamics analysis. By investigating a periodic semiflow on a suitably chosen phase space, the global dynamics of a threshold type is established: all solutions either go to zero when basic reproduction ratio is less than one, or stabilize at a positive periodic state when the reproduction ratio is greater than one. The synthesized approach developed here is applicable to broader contexts of investigating biological systems with seasonal developmental durations.

  8. Variation in foraging success among predators and its implications for population dynamics.

    Science.gov (United States)

    Okuyama, Toshinori

    2017-01-01

    The effects of the expected predation rate on population dynamics have been studied intensively, but little is known about the effects of predation rate variability (i.e., predator individuals having variable foraging success) on population dynamics. In this study, variation in foraging success among predators was quantified by observing the predation of the wolf spider Pardosa pseudoannulata on the cricket Gryllus bimaculatus in the laboratory. A population model was then developed, and the effect of foraging variability on predator-prey dynamics was examined by incorporating levels of variation comparable to those quantified in the experiment. The variability in the foraging success among spiders was greater than would be expected by chance (i.e., the random allocation of prey to predators). The foraging variation was density-dependent; it became higher as the predator density increased. A population model that incorporates foraging variation shows that the variation influences population dynamics by affecting the numerical response of predators. In particular, the variation induces negative density-dependent effects among predators and stabilizes predator-prey dynamics.

  9. Control mechanisms on the ctenophore (Mnemiopsis Leidyi) population dynamics: a modelling study

    Science.gov (United States)

    Salihoglu, Baris; Fach, Bettina; Oguz, Temel

    2010-05-01

    A comprehensive understanding of the mechanisms that control the ctenophore Mnemiopsis leidyi blooms in the Black Sea is studied with a zero-dimensional population based model. The stage resolving model considers detailed weight and population growth dynamics under four stages of model-ctenophore. The model is able to represent consistent development patterns, while reflecting the physiological complexity of a population of Mnemiopsis leidyi. Model is used to analyse the influence of temperature and food variability on Mnemiopsis leidyi reproduction and outburst. Model results demonstrated how food sources regulated the growth rates under changing temperatures. Model results suggest that different nutritonal requirement of each stage can be critical for population growth.

  10. Population dynamics of intraguild predation in a lattice gas system.

    Science.gov (United States)

    Wang, Yuanshi; Wu, Hong

    2015-01-01

    In the system of intraguild predation (IGP) we are concerned with, species that are in a predator-prey relationship, also compete for shared resources (space or food). While several models have been established to characterize IGP, mechanisms by which IG prey and IG predator can coexist in IGP systems with spatial competition, have not been shown. This paper considers an IGP model, which is derived from reactions on lattice and has a form similar to that of Lotka-Volterra equations. Dynamics of the model demonstrate properties of IGP and mechanisms by which the IGP leads to coexistence of species and occurrence of alternative states. Intermediate predation is shown to lead to persistence of the predator, while extremely big predation can lead to extinction of one/both species and extremely small predation can lead to extinction of the predator. Numerical computations confirm and extend our results. While empirical observations typically exhibit coexistence of IG predator and IG prey, theoretical analysis in this work demonstrates exact conditions under which this coexistence can occur. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Ecological change predicts population dynamics and genetic diversity over 120 000 years.

    Science.gov (United States)

    Horreo, Jose Luis; Jiménez-Valverde, Alberto; Fitze, Patrick S

    2016-05-01

    While ecological effects on short-term population dynamics are well understood, their effects over millennia are difficult to demonstrate and convincing evidence is scant. Using coalescent methods, we analysed past population dynamics of three lizard species (Psammodromus hispanicus, P. edwardsianus, P. occidentalis) and linked the results with climate change data covering the same temporal horizon (120 000 years). An increase in population size over time was observed in two species, and in P. occidentalis, no change was observed. Temporal changes in temperature seasonality and the maximum temperature of the warmest month were congruent with changes in population dynamics observed for the three species and both variables affected population density, either directly or indirectly (via a life-history trait). These results constitute the first solid link between ecological change and long-term population dynamics. The results moreover suggest that ecological change leaves genetic signatures that can be retrospectively traced, providing evidence that ecological change is a crucial driver of genetic diversity and speciation.

  12. Complex transient dynamics of stage-structured populations in response to environmental changes.

    Science.gov (United States)

    Massie, Thomas M; Ryabov, Alexei; Blasius, Bernd; Weithoff, Guntram; Gaedke, Ursula

    2013-07-01

    Stage structures of populations can have a profound influence on their dynamics. However, not much is known about the transient dynamics that follow a disturbance in such systems. Here we combined chemostat experiments with dynamical modeling to study the response of the phytoplankton species Chlorella vulgaris to press perturbations. From an initially stable steady state, we altered either the concentration or dilution rate of a growth-limiting resource. This disturbance induced a complex transient response-characterized by the possible onset of oscillations-before population numbers relaxed to a new steady state. Thus, cell numbers could initially change in the opposite direction of the long-term change. We present quantitative indexes to characterize the transients and to show that the dynamic response is dependent on the degree of synchronization among life stages, which itself depends on the state of the population before perturbation. That is, we show how identical future steady states can be approached via different transients depending on the initial population structure. Our experimental results are supported by a size-structured model that accounts for interplay between cell-cycle and population-level processes and that includes resource-dependent variability in cell size. Our results should be relevant to other populations with a stage structure including organisms of higher order.

  13. The importance of temperature fluctuations in understanding mosquito population dynamics and malaria risk

    Science.gov (United States)

    Nelson, William A.; Paaijmans, Krijn P.; Thomas, Matthew B.; Bjørnstad, Ottar N.

    2017-01-01

    Temperature is a key environmental driver of Anopheles mosquito population dynamics; understanding its central role is important for these malaria vectors. Mosquito population responses to temperature fluctuations, though important across the life history, are poorly understood at a population level. We used stage-structured, temperature-dependent delay-differential equations to conduct a detailed exploration of the impacts of diurnal and annual temperature fluctuations on mosquito population dynamics. The model allows exploration of temperature-driven temporal changes in adult age structure, giving insights into the population’s capacity to vector malaria parasites. Because of temperature-dependent shifts in age structure, the abundance of potentially infectious mosquitoes varies temporally, and does not necessarily mirror the dynamics of the total adult population. In addition to conducting the first comprehensive theoretical exploration of fluctuating temperatures on mosquito population dynamics, we analysed observed temperatures at four locations in Africa covering a range of environmental conditions. We found both temperature and precipitation are needed to explain the observed malaria season in these locations, enhancing our understanding of the drivers of malaria seasonality and how temporal disease risk may shift in response to temperature changes. This approach, tracking both mosquito abundance and age structure, may be a powerful tool for understanding current and future malaria risk.

  14. Population dynamics of the pioneer population of Daphnia parvula, Fordyce during the invasion of Lake Candia (Northern Italy

    Directory of Open Access Journals (Sweden)

    Fiorenza MARGARITORA

    2004-02-01

    Full Text Available Since the 1970s Daphnia parvula, Fordyce, originally distributed in the New World, has been invading Europe. In Italy D. parvula first appeared in the shallow, eutrophic Lake Candia (Piedmont, Northern Italy during September 2002. Although several studies have documented D. parvula dispersal in European habitats, little is known about the life cycle and ecology of this invader in its new habitats. Invasion success depends on the ability of the invader population to perform well in the new ecosystem, which in turn results from the interaction between the characteristics of the invader and those of the invaded environment and its resident community. Early detection of D. parvula in the intensively studied Lake Candia offered an excellent opportunity to study the performance of the pioneer population and to document the early phases of invasion. Following the dynamics of the pioneer D. parvula population provided evidence of a high level of gamogenetic reproduction during most periods of population development. The production of males started at the onset of population growth prior to ephippia formation. The sex ratio ranged from 0.1 to 0.33 males per female with a maximum in October when males accounted for up to 24% of the total population density. The percentage of ephippia (free ephippia + ephippial females out of the total population density ranged from 3 to 23%. The large pool of resting eggs produced by the pioneer population of D. parvula in Lake Candia might reflect a strategy for increasing the probability of survival and establishment in the new environment.

  15. Relative importance of natural disturbances and habitat degradation on snail kite population dynamics

    Science.gov (United States)

    Martin, J.; Kitchens, W.M.; Cattau, Christopher E.; Oli, M.K.

    2008-01-01

    Natural disturbances and habitat degradation are major factors influencing the dynamics and persistence of many wildlife populations, yet few large-scale studies have explored the relative influence of these factors on the dynamics and persistence of animal populations. We used longterm demographic data and matrix population models to examine the potential effects of habitat degradation and natural disturbances on the dynamics of the endangered snail kite Rostrhamus sociabilis in Florida, USA. We found that estimates of stochastic population growth rate were low (0.90). Population growth rate (??) during the first half or our study period (1992 to 1998) was substantially greater than during the second half (1999 to 2005). These 2 periods were characterized by contrasting hydrological conditions. Although ?? was most sensitive to changes in adult survival, the analysis of life table response experiments revealed that a reduction in fertility of kites accounted for >80% of the observed decline in population growth rate. We examined the possibility that the reduction in ?? was caused by (1) habitat degradation due to management, (2) an increase in frequency of moderate drying events in recent years, and (3) both habitat degradation and an increase in frequency of moderate drying events. Our results suggest that both factors could potentially contribute to a large decrease in population growth rate. Our study highlights the importance of simultaneously considering short- and long-term effects of disturbances when modeling population dynamics. Indeed, focusing exclusively on one type of effect may be misleading to both our understanding of the ecological dynamics of the system and to management. The relevance of our results to management is heightened because the snail kite has been selected as a key performance measure of one of the most ambitious ecosystem restoration projects ever undertaken. ?? Inter-Research 2008.

  16. The influence of synaptic weight distribution on neuronal population dynamics.

    Directory of Open Access Journals (Sweden)

    Ramakrishnan Iyer

    2013-10-01

    Full Text Available The manner in which different distributions of synaptic weights onto cortical neurons shape their spiking activity remains open. To characterize a homogeneous neuronal population, we use the master equation for generalized leaky integrate-and-fire neurons with shot-noise synapses. We develop fast semi-analytic numerical methods to solve this equation for either current or conductance synapses, with and without synaptic depression. We show that its solutions match simulations of equivalent neuronal networks better than those of the Fokker-Planck equation and we compute bounds on the network response to non-instantaneous synapses. We apply these methods to study different synaptic weight distributions in feed-forward networks. We characterize the synaptic amplitude distributions using a set of measures, called tail weight numbers, designed to quantify the preponderance of very strong synapses. Even if synaptic amplitude distributions are equated for both the total current and average synaptic weight, distributions with sparse but strong synapses produce higher responses for small inputs, leading to a larger operating range. Furthermore, despite their small number, such synapses enable the network to respond faster and with more stability in the face of external fluctuations.

  17. A scoping review and prevalence analysis of soil-transmitted helminth infections in Honduras.

    Directory of Open Access Journals (Sweden)

    Ana Lourdes Sanchez

    Full Text Available Honduras is endemic for soil-transmitted helminth (STH infections, but critical information gaps still remain on the prevalence and intensity of these infections as well as on their spatial distribution at subnational levels.Firstly, to review the research activity on STH infections in Honduras and secondly, to carry out a national prevalence analysis and map the geographical distribution of these infections in children.A systematic search was conducted of the published and grey literature to identify scientific work on the impact and prevalence of STH infections done between May 1930 and June 30, 2012. International databases and Honduran journals were searched. Grey literature was gleaned from local libraries and key informants. Select studies conducted between 2001 and 2012 were used to produce prevalence maps and to investigate association between STH prevalence and socio-economic and environmental factors.Of 257 identified studies, 211 (21.4% peer-reviewed were retained for analysis and categorized as clinical research (10.9%, treatment efficacy studies (8.1% or epidemiological studies (81%. Prevalence analysis and geographical mapping included 36 epidemiological studies from Honduras's 18 departments and 23% of its municipalities. Overall STH prevalence was >50% in 40.6% of municipalities. Prevalences above 20% for each trichuriasis, ascariasis, and hookworm infection were found in 68%, 47.8%, and 7.2% of studied municipalities, respectively. Municipalities with lower human development index, less access to of potable water, and with higher annual precipitation showed higher STH prevalences.This is the first study to provide a comprehensive historic review of STH research activity and prevalence in Honduras, revealing important knowledge gaps related to infection risk factors, disease burden, and anti-parasitic drug efficacy, among others. Our decade-long prevalence analysis reveals geographical differences in STH prevalence and these

  18. A scoping review and prevalence analysis of soil-transmitted helminth infections in Honduras.

    Science.gov (United States)

    Sanchez, Ana Lourdes; Gabrie, José Antonio; Rueda, María Mercedes; Mejia, Rosa Elena; Bottazzi, Maria Elena; Canales, Maritza

    2014-01-01

    Honduras is endemic for soil-transmitted helminth (STH) infections, but critical information gaps still remain on the prevalence and intensity of these infections as well as on their spatial distribution at subnational levels. Firstly, to review the research activity on STH infections in Honduras and secondly, to carry out a national prevalence analysis and map the geographical distribution of these infections in children. A systematic search was conducted of the published and grey literature to identify scientific work on the impact and prevalence of STH infections done between May 1930 and June 30, 2012. International databases and Honduran journals were searched. Grey literature was gleaned from local libraries and key informants. Select studies conducted between 2001 and 2012 were used to produce prevalence maps and to investigate association between STH prevalence and socio-economic and environmental factors. Of 257 identified studies, 211 (21.4% peer-reviewed) were retained for analysis and categorized as clinical research (10.9%), treatment efficacy studies (8.1%) or epidemiological studies (81%). Prevalence analysis and geographical mapping included 36 epidemiological studies from Honduras's 18 departments and 23% of its municipalities. Overall STH prevalence was >50% in 40.6% of municipalities. Prevalences above 20% for each trichuriasis, ascariasis, and hookworm infection were found in 68%, 47.8%, and 7.2% of studied municipalities, respectively. Municipalities with lower human development index, less access to of potable water, and with higher annual precipitation showed higher STH prevalences. This is the first study to provide a comprehensive historic review of STH research activity and prevalence in Honduras, revealing important knowledge gaps related to infection risk factors, disease burden, and anti-parasitic drug efficacy, among others. Our decade-long prevalence analysis reveals geographical differences in STH prevalence and these findings

  19. 'Wildlife 2001: Populations', an International Conference on Population Dynamics and Management of Vertebrates

    CERN Document Server

    Barrett, Reginald

    1992-01-01

    In 1984, a conference called Wildlife 2000: Modeling habitat relationships of terrestrial vertebrates, was held at Stanford Sierra Camp at Fallen Leaf Lake in the Sierra Nevada Mountains of California. The conference was well-received, and the published volume (Verner, J. , M. L. Morrison, and C. J. Ralph, editors. 1986. Wildlife 2000: modeling habitat relationships of terrestrial vertebrates, University of Wisconsin Press, Madison, Wisconsin, USA) proved to be a landmark publication that received a book award by The Wildlife Society. Wildlife 2001: populations was a followup conference with emphasis on the other major biological field of wildlife conservation and management, populations. It was held on July 29-31, 1991, at the Oakland Airport Hilton Hotel in Oakland, California, in accordance with our intent that this conference have a much stronger international representation than did Wildlife 2000. The goal of the conference was to bring together an international group of specialists to address the state ...

  20. Demographic characteristics of circumpolar caribou populations: ecotypes, ecological constraints, releases, and population dynamics

    OpenAIRE

    Mallory, F.F.; T.L. Hillis

    1998-01-01

    Data on the status of caribou {Rangifer tarandus) herds throughout the circumpolar region during the last 20 years were obtained from the literature and personal communication with researchers. Information was analysed in relation to ecotype (insular, montane, barren-ground, and woodland/forest), population status (increasing, stable, decreasing), herd size, human impact, and temporal change in number. The data support the conclusions (1) that each ecotype is exposed to different ecological c...

  1. Population dynamics of Neisseria gonorrhoeae in Shanghai, China: a comparative study

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2010-01-01

    Full Text Available Abstract Background Gonorrhea is a major sexually transmitted disease (STD in many countries worldwide. The emergence of fluoroquinolone resistance has complicated efforts to control and treat this disease. We report the first study of the evolutionary processes acting on transmission dynamics of a resistant gonococcal population from Shanghai, China. We compare these findings with our previous study of the evolution of a fluoroquinolone sensitive gonococcal population from Baltimore, MD. Methods Ninety six gonococcal samples were collected from male patients in Shanghai, China. All samples were fluoroquinolone resistant. Seven MLST housekeeping genes, two fluoroquinolone resistance genes (gyrA and parC and the porB gene were sequenced and subjected to population genetic and evolutionary analyses. We estimated genetic diversity, recombination, growth, and selective pressure. The evolutionary history and population dynamics of the Shanghai population were also inferred and compared with that observed in a fluoroquinolone sensitive gonococcal population from Baltimore. Results For both populations, mutation plays a larger role than recombination in the evolution of the porB gene, whereas the latter seems to be the main force driving the evolution of housekeeping and fluoroquinolone resistance genes. In both populations there was evidence for positively selected sites in all genes analyzed. The phylogenetic analyses showed no temporal clustering in the Shanghai gonococcal population, nor did we detect shared allelic profiles between the Shanghai and the Baltimore populations. Past population dynamics of gonococcal strains from Shanghai showed a rising relative effective population size (Ne in MLST genes with a declining relative Ne for gyrA and parC, whereas among sensitive strains from Baltimore we previously observed concordance among these genes. In both Shanghai and Baltimore, the past population dynamics of gonococcal strains tracked changes

  2. Mesola red deer: physical characteristics, population dynamics and conservation perspectives

    Directory of Open Access Journals (Sweden)

    Stefano Mattioli

    2003-10-01

    Full Text Available Abstract The biometry, demography and genetics of red deer Cervus elaphus of Mesola Wood (NE Italy, are presented and discussed in relation to the conservation of this population. Modest body size, low stature, oversimplified antlers and a low reproductive performance characterise red deer from Mesola Wood. The mitochondrial genome showed a private haplotype, different from other red deer in Italy and central Europe. The uniqueness of this nucleus and its biogeographic importance make a long-term conservation plan particularly urgent. Management measures such as fallow deer reduction, winter feeding and pasture mowing were tested, giving promising results. The physical condition of the animals improved, calf and adult mortality declined, and a few cases of antlers with bez tine or crown were reported in this study after four decades. Riassunto Il Cervo della Mesola: caratteristiche fisiche, dinamica di popolazione e prospettive di conservazione La biometria, la demografia e la genetica del cervo Cervus elaphus del Gran Bosco della Mesola (Italia nord-orientale, vengono presentate e discusse in relazione alla salvaguardia di questa popolazione. Il cervo della Mesola risulta caratterizzato dalle modeste dimensioni corporee, dalla struttura semplificata dei palchi e da un basso rendimento riproduttivo. L'analisi del genoma mitocondriale ha evidenziato un aplotipo privato, diverso da quello degli altri cervi italiani e centroeuropei. L'unicità di questo nucleo e la sua importanza biogeografica rendono particolarmente urgente un piano di conservazione a lungo termine. Sono stati verificati interventi gestionali quali la riduzione numerica dei daini, il foraggiamento invernale e lo sfalcio delle superfici a pascolo, con risultati promettenti. Le condizioni fisiche degli animali sono migliorate, la mortalità tra i piccoli e gli adulti è diminuita, e sono stati registrati alcuni

  3. Langevin Formalism as the Basis for the Unification of Population Dynamics

    Science.gov (United States)

    de Vladar, Harold P.

    2005-03-01

    We are presenting a simple reformulation to population dynamics that generalizes many growth functions. The reformulation consists of two equations, one for population size, and one for the growth rate. The model shows that even when a population is density-dependent the dynamics of its growth rate does not depend explicitly neither on population size nor on the carrying capacity. Actually, the growth rate is uncoupled from the population size equation. The model has only two parameters: a Malthusian parameter ρ and an interaction coefficient θ. Distinct values of these parameters reproduce the family of θ-logistics, the van Bertalanffy, Gompertz and Potential Growth equations, among other possibilities. Stochastic perturbations to the Malthusian parameter leads to a Langevin form of stochastic differential equation consisting of a family of cubic potentials perturbed with multiplicative noise. Using these equtions, we derive the stationary Fokker Plank distribution which which shows that in the stationary dynamics, density dependent populations fluctuate around a mean size that is shifted from the carrying capacity proportionally to the noise intensity. We also study which kinds of populations are susceptible to noise induced transitions.

  4. Hydrogeochemical investigation of six geothermal sites in Honduras, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.E.; Truesdell, A.H.; Grigsby, C.O.; Janik, C.J.; Shevenell, L.A.; Paredes, J.R.; Gutierrez, J.W.; Trujillo, Jr.; Counce, D.A.

    1987-06-01

    We conducted detailed hydrogeochemical investigations at six geothermal sites in western Honduras: Azacualpa, El Olivar, Pavana, Platanares, Sambo Creek, and San Ignacio. None of the sites is associated with Quaternary silicic volcanism, although El Olivar lies adjacent to a small Quaternary basalt field and Pavana is part of a belt of hot spring activity parallel to and 35 km east of the Central American volcanic arc. None of the sites contains acid-sulfate waters indicative of vapor-dominated conditions. Thermal fluids are characterized by pH between 7 and 10, Cl<125 mg/l, HCO/sub 3/>Cl, SO/sub 4/greater than or equal toCl, Bless than or equal to17 mg/l, Liless than or equal to4 mg/l, and Asless than or equal to1.25 mg/l. Stable isotope analyses of the water show that recharge to the geothermal systems generally occurs from areas of higher elevation adjacent to the sites. Tritium contents of apparently undiluted thermal fluids range from 0 to 0.4 T.U., indicating residence times of fluids in the systems of more than 500 y. Various geochemical indicators show that mixing of hot and cold end-member fluids occurs in the system at Platanares and, to a lesser degree, in the systems at San Ignacio and Azacualpa. No mixing is apparent in the fluids discharging at Pavana, Sambo Creek, or El Olivar. Boiling is the dominant process responsible for subtle geochemical variations at Azacualpa and, possibly, San Ignacio. Our best estimates of subsurface reservoir temperatures are 225/sup 0/C at Platanares, 190/sup 0/C at San Ignacio, 185/sup 0/C at Azacualpa, 155/sup 0/C at Sambo Creek, 150/sup 0/C at Pavana, and 120/sup 0/C at El Olivar. The estimated power output of the three hottest sites is 45 thermal megawatts at Platanares, 14 thermal megawatts at San Ignacio, and 13 thermal megawatts at Azacualpa.

  5. Boom or bust? A comparative analysis of transient population dynamics in plants

    DEFF Research Database (Denmark)

    Stott, Iain; Franco, Miguel; Carslake, David

    2010-01-01

    researchers as further possible effectors of complicated dynamics. Previously published methods of transient analysis have tended to require knowledge of initial population structure. However, this has been overcome by the recent development of the parametric Kreiss bound (which describes how large...... a population must become before reaching its maximum possible transient amplification following a disturbance) and the extension of this and other transient indices to simultaneously describe both amplified and attenuated transient dynamics. We apply the Kreiss bound and other transient indices to a data base...... worrying artefact of basic model parameterization. Synthesis. Transient indices describe how big or how small plant populations can get, en route to long-term stable rates of increase or decline. The patterns we found in the potential for transient dynamics, across many species of plants, suggest...

  6. A framework for studying transient dynamics of population projection matrix models

    DEFF Research Database (Denmark)

    Stott, Iain; Townley, Stuart; Hodgson, David James

    2011-01-01

    arise even from simple models following ecological disturbances or perturbations. Recent interest in such transient dynamics has led to diverse methodologies for their quantification in density-independent, time-invariant population projection matrix (PPM) models, but the fragmented nature...... of this literature has stifled the widespread analysis of transients. We review the literature on transient analyses of linear PPM models and synthesise a coherent framework. We promote the use of standardised indices, and categorise indices according to their focus on either convergence times or transient...... population density, and on either transient bounds or case-specific transient dynamics. We use a large database of empirical PPM models to explore relationships between indices of transient dynamics. This analysis promotes the use of population inertia as a simple, versatile and informative predictor...

  7. Simulation of mosquitoes population dynamic based on rainfall and average daily temperature

    Science.gov (United States)

    Widayani, H.; Seprianus, Nuraini, N.; Arum, J.

    2014-02-01

    This paper proposed rainfall and average daily temperature approximation functions using least square method with trigonometry polynomial. Error value from this method is better than Fast Fourier Transform method. This approximation is used to accommodate climatic factors into deterministic model of mosquitoes population by constructing a carrying capacity function which contains rainfall and average daily temperature functions. We develop a mathematical model for mosquitoes population dynamic which formulated by Yang et al (2010) with dynamic parameter of a daily rainfall as well as temperature on that model. Two fixed points, trivial and non-trivial, are obtained when constant entomological parameters assumed. Basic offspring number, Q0 as mosquitoes reproduction parameter is constructed. Non-trivial fixed point is stable if and only if Q0 > 1. Numerical simulation shown the dynamics of mosquitoes population significantly affected by rainfall and average daily temperature function.

  8. Modelling the dynamics of feral alfalfa populations and its management implications.

    Directory of Open Access Journals (Sweden)

    Muthukumar V Bagavathiannan

    Full Text Available BACKGROUND: Feral populations of cultivated crops can pose challenges to novel trait confinement within agricultural landscapes. Simulation models can be helpful in investigating the underlying dynamics of feral populations and determining suitable management options. METHODOLOGY/PRINCIPAL FINDINGS: We developed a stage-structured matrix population model for roadside feral alfalfa populations occurring in southern Manitoba, Canada. The model accounted for the existence of density-dependence and recruitment subsidy in feral populations. We used the model to investigate the long-term dynamics of feral alfalfa populations, and to evaluate the effectiveness of simulated management strategies such as herbicide application and mowing in controlling feral alfalfa. Results suggest that alfalfa populations occurring in roadside habitats can be persistent and less likely to go extinct under current roadverge management scenarios. Management attempts focused on controlling adult plants alone can be counterproductive due to the presence of density-dependent effects. Targeted herbicide application, which can achieve complete control of seedlings, rosettes and established plants, will be an effective strategy, but the seedbank population may contribute to new recruits. In regions where roadside mowing is regularly practiced, devising a timely mowing strategy (early- to mid-August for southern Manitoba, one that can totally prevent seed production, will be a feasible option for managing feral alfalfa populations. CONCLUSIONS/SIGNIFICANCE: Feral alfalfa populations can be persistent in roadside habitats. Timely mowing or regular targeted herbicide application will be effective in managing feral alfalfa populations and limit feral-population-mediated gene flow in alfalfa. However, in the context of novel trait confinement, the extent to which feral alfalfa populations need to be managed will be dictated by the tolerance levels established by specific production

  9. Using dynamic population simulations to extend resource selection analyses and prioritize habitats for conservation

    Science.gov (United States)

    Heinrichs, Julie; Aldridge, Cameron; O'Donnell, Michael; Schumaker, Nathan

    2017-01-01

    Prioritizing habitats for conservation is a challenging task, particularly for species with fluctuating populations and seasonally dynamic habitat needs. Although the use of resource selection models to identify and prioritize habitat for conservation is increasingly common, their ability to characterize important long-term habitats for dynamic populations are variable. To examine how habitats might be prioritized differently if resource selection was directly and dynamically linked with population fluctuations and movement limitations among seasonal habitats, we constructed a spatially explicit individual-based model for a dramatically fluctuating population requiring temporally varying resources. Using greater sage-grouse (Centrocercus urophasianus) in Wyoming as a case study, we used resource selection function maps to guide seasonal movement and habitat selection, but emergent population dynamics and simulated movement limitations modified long-term habitat occupancy. We compared priority habitats in RSF maps to long-term simulated habitat use. We examined the circumstances under which the explicit consideration of movement limitations, in combination with population fluctuations and trends, are likely to alter predictions of important habitats. In doing so, we assessed the future occupancy of protected areas under alternative population and habitat conditions. Habitat prioritizations based on resource selection models alone predicted high use in isolated parcels of habitat and in areas with low connectivity among seasonal habitats. In contrast, results based on more biologically-informed simulations emphasized central and connected areas near high-density populations, sometimes predicted to be low selection value. Dynamic models of habitat use can provide additional biological realism that can extend, and in some cases, contradict habitat use predictions generated from short-term or static resource selection analyses. The explicit inclusion of population

  10. Predation, Competition, and Abiotic Disturbance: Population Dynamics of Small Mammals

    Energy Technology Data Exchange (ETDEWEB)

    Yunger, John A.; /Northern Illinois U. /Northern Illinois U.

    1996-01-01

    Predation and food availability have been implicated in annual non-cyclic fluctuations of vertebrate prey at mid-latitudes. The timing and magnitude of these factors are unclear due to a lack of large-scale field experiments, little attention to interactions, and a failure to closely link vertebrate predators with their prey. From October 1992 to January 1996, small mammal populations were censused on eight 0.6 ha plots at monthly intervals in a 32-ha prairie restoration at Fermi National Accelerator Laboratory, Illinois. Terrestrial vertebrate predators were excluded after July 1993 from four of the eight plots and canid diets monitored. Both terrestrial and avian vertebrate predators were excluded in March 1994. During 1993 small mammal densities (i.e., Microtus Pennsylvanicus, Peromyscus leucopus, and P. maniculatus) were relatively high. Following peak densities in late summer, Microtus numbers wer 2-3x greater on exclusion plots relative to controls due to preferential selection of Microtus by canids, as reflected in dits. Following an ice-storm and crash in small mammal numbers (particularly Microtus), vertebrate predator exclusion had no detectable effect on P. leucopus numbers, probably due to an abundance of alternative prey (i.e., Sylvilagus floridanus). Meadow vole numbers began to increase in Fall 1995, and a numerical effect of predator exclusion, similar to that in 1993, was observed. Predator exclusion had no detectable effect on the movements and spatial patterns of Microtus during 1993. There was a significant decrease in home range and a significant increase in home range overlap for P. leucopus on the predator exclusion plots. The change in spatial behavior may be due to interspecific competition with Microtus resulting from increased densities on exclusion plots. Thus, predators had an indirect effect on P. leucopus spatial patterns mediated through M. Pennsylvanicus. The role of food limitation was studied using natural and manipulative

  11. Population genetic structure and historical population dynamics of the South American sea lion, Otaria flavescens, in north-central Patagonia.

    Science.gov (United States)

    Túnez, Juan I; Cappozzo, Humberto L; Nardelli, Maximiliano; Cassini, Marcelo H

    2010-08-01

    The north-central Patagonian coast is the sea lions most abundant area in Argentina. As occurs along the entire Atlantic coast, the distribution of breeding colonies at this smaller geographical scale is also patchy, showing at least three areas with breeding activity. We study the genetic structure and historical population dynamics of the species in five colonies in this area, analysing a 508 base-pair segment of the D-loop control region. Otaria flavescens showed 10 haplotypes with 12 polymorphic sites. The genealogical relationship between haplotypes revealed a shallow pattern of phylogeographic structure. The analysis of molecular variance showed significant differences between colonies, however, pairwise comparisons only indicate significant differences between a pair of colonies belonging to different breeding areas. The pattern of haplotype differentiation and the mismatch distribution analysis suggest a possible bottleneck that would have occurred 64,000 years ago, followed by a demographic expansion of the three southernmost colonies. Thus, the historical population dynamics of O. flavescens in north-central Patagonia appears to be closely related with the dynamics of the Late Pleistocene glaciations.

  12. Catalysis of Protein Folding by Chaperones Accelerates Evolutionary Dynamics in Adapting Cell Populations

    OpenAIRE

    Murat Cetinbaş; Shakhnovich, Eugene I.

    2013-01-01

    Although molecular chaperones are essential components of protein homeostatic machinery, their mechanism of action and impact on adaptation and evolutionary dynamics remain controversial. Here we developed a physics-based ab initio multi-scale model of a living cell for population dynamics simulations to elucidate the effect of chaperones on adaptive evolution. The 6-loci genomes of model cells encode model proteins, whose folding and interactions in cellular milieu can be evaluated exactly f...

  13. Dynamics and recovery of a sediment-exposed Chironomus riparius population: A modelling approach.

    Science.gov (United States)

    Diepens, Noël J; Beltman, Wim H J; Koelmans, Albert A; Van den Brink, Paul J; Baveco, Johannes M

    2016-06-01

    Models can be used to assess long-term risks of sediment-bound contaminants at the population level. However, these models usually lack the coupling between chemical fate in the sediment, toxicokinetic-toxicodynamic processes in individuals and propagation of individual-level effects to the population. We developed a population model that includes all these processes, and used it to assess the importance of chemical uptake routes on a Chironomus riparius population after pulsed exposure to the pesticide chlorpyrifos. We show that particle ingestion is an important additional exposure pathway affecting C. riparius population dynamics and recovery. Models ignoring particle ingestion underestimate the impact and the required recovery times, which implies that they underestimate risks of sediment-bound chemicals. Additional scenario studies showed the importance of selecting the biologically relevant sediment layer and showed population effects in the long term.

  14. Improving Bayesian population dynamics inference: a coalescent-based model for multiple loci.

    Science.gov (United States)

    Gill, Mandev S; Lemey, Philippe; Faria, Nuno R; Rambaut, Andrew; Shapiro, Beth; Suchard, Marc A

    2013-03-01

    Effective population size is fundamental in population genetics and characterizes genetic diversity. To infer past population dynamics from molecular sequence data, coalescent-based models have been developed for Bayesian nonparametric estimation of effective population size over time. Among the most successful is a Gaussian Markov random field (GMRF) model for a single gene locus. Here, we present a generalization of the GMRF model that allows for the analysis of multilocus sequence data. Using simulated data, we demonstrate the improved performance of our method to recover true population trajectories and the time to the most recent common ancestor (TMRCA). We analyze a multilocus alignment of HIV-1 CRF02_AG gene sequences sampled from Cameroon. Our results are consistent with HIV prevalence data and uncover some aspects of the population history that go undetected in Bayesian parametric estimation. Finally, we recover an older and more reconcilable TMRCA for a classic ancient DNA data set.

  15. Strong dispersal in a parasitoid wasp overwhelms habitat fragmentation and host population dynamics.

    Science.gov (United States)

    Couchoux, C; Seppä, P; van Nouhuys, S

    2016-07-01

    The population dynamics of a parasite depend on species traits, host dynamics and the environment. Those dynamics are reflected in the genetic structure of the population. Habitat fragmentation has a greater impact on parasites than on their hosts because resource distribution is increasingly fragmented for species at higher trophic levels. This could lead to either more or less genetic structure than the host, depending on the relative dispersal rates of species. We examined the spatial genetic structure of the parasitoid wasp Hyposoter horticola, and how it was influenced by dispersal, host population dynamics and habitat fragmentation. The host, the Glanville fritillary butterfly, lives as a metapopulation in a fragmented landscape in the Åland Islands, Finland. We collected wasps throughout the 50 by 70 km archipelago and determined the genetic diversity, spatial population structure and genetic differentiation using 14 neutral DNA microsatellite loci. We compared the genetic structure of the wasp with that of the host butterfly using published genetic data collected over the shared landscape. Using maternity assignment, we also identified full-siblings among the sampled parasitoids to estimate the dispersal range of individual females. We found that because the parasitoid is dispersive, it has low genetic structure, is not very sensitive to habitat fragmentation and has less spatial genetic structure than its butterfly host. The wasp is sensitive to regional rather than local host dynamics, and there is a geographic mosaic landscape for antagonistic co-evolution of host resistance and parasite virulence. © 2016 John Wiley & Sons Ltd.

  16. Population Dynamics and the Optical Absorption in Hybrid Metal Nanoparticle - Semiconductor Quantum dot Nanosystem

    CERN Document Server

    Kim, Nam-Chol; Ko, Myong-Chol; So, Guang Hyok; Kim, Il-Guang

    2015-01-01

    We studied theoretically the population dynamics and the absorption spectrum of hybrid nanosystem consisted of a matal nanoparticle (MNP) and a semiconductor quantum dot(SQD). We investigated the exciton-plasmon coupling effects on the population dynamics and the absorption properties of the nanostructure. Our results show that the nonlinear optical response of the hybrid nanosystem can be greatly enhanced or depressed due to the exciton-plasmon couplings. The results obtained here may have the potential applications of nanoscale optical devices such as optical switches and quantum devices such as a single photon transistor.

  17. 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...... 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...... 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...

  18. Predicting extinction risks under climate change: coupling stochastic population models with dynamic bioclimatic habitat models.

    Science.gov (United States)

    Keith, David A; Akçakaya, H Resit; Thuiller, Wilfried; Midgley, Guy F; Pearson, Richard G; Phillips, Steven J; Regan, Helen M; Araújo, Miguel B; Rebelo, Tony G

    2008-10-23

    Species responses to climate change may be influenced by changes in available habitat, as well as population processes, species interactions and interactions between demographic and landscape dynamics. Current methods for assessing these responses fail to provide an integrated view of these influences because they deal with habitat change or population dynamics, but rarely both. In this study, we linked a time series of habitat suitability models with spatially explicit stochastic population models to explore factors that influence the viability of plant species populations under stable and changing climate scenarios in South African fynbos, a global biodiversity hot spot. Results indicate that complex interactions between life history, disturbance regime and distribution pattern mediate species extinction risks under climate change. Our novel mechanistic approach allows more complete and direct appraisal of future biotic responses than do static bioclimatic habitat modelling approaches, and will ultimately support development of more effective conservation strategies to mitigate biodiversity losses due to climate change.

  19. Population dynamics of the brown alga Himanthalia elongata under harvesting pressure

    Science.gov (United States)

    Stagnol, Doriane; Michel, Renaud; Davoult, Dominique

    2016-06-01

    Through experimental harvesting, followed by a 12-month monitoring of demographic attributes, we tested the influence of harvesting on the population dynamics of Himanthalia elongata. We further explore the data to test the hypothesis that the canopy would exert a negative effect on the other developmental stages (intraspecific competition) throughout the recovery cycle of the population. This showed that the H. elongata canopy plays a marked seasonal role not by precluding the presence of other developmental stages but by delaying or preventing their growth and development. The removal of the canopy facilitates the transition from one developmental stage to another, eventually permitting a fast recovery of size structure in the population. This study allows us to integrate population dynamics and intraspecific relationships in our understanding of macroalgal recovery patterns.

  20. An Algorithm for the Stochastic Simulation of Gene Expression and Heterogeneous Population Dynamics

    CERN Document Server

    Charlebois, Daniel A; Fraser, Dawn; Kaern, Mads

    2011-01-01

    We present an algorithm for the stochastic simulation of gene expression and heterogeneous population dynamics. The algorithm combines an exact method to simulate molecular-level fluctuations in single cells and a constant-number Monte Carlo method to simulate time-dependent statistical characteristics of growing cell populations. To benchmark performance, we compare simulation results with steadystate and time-dependent analytical solutions for several scenarios, including steadystate and time-dependent gene expression, and the effects on population heterogeneity of cell growth, division, and DNA replication. This comparison demonstrates that the algorithm provides an efficient and accurate approach to simulate how complex biological features influence gene expression. We also use the algorithm to model gene expression dynamics within "bet-hedging" cell populations during their adaption to environmental stress. These simulations indicate that the algorithm provides a framework suitable for simulating and ana...