Displaying publications 41 - 60 of 318 in total

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  1. Islam and Science: the Islamic world
    Abbott A, Cyranoski D, Masood E
    Nature, 2006 Nov 2;444(7115):20-1.
    PMID: 17080056
    Matched MeSH terms: Population Dynamics
  2. Soil-related variations in the population dynamics of six dipterocarp tree species with strong habitat preferences
    Yamada T, Yamada Y, Okuda T, Fletcher C
    Oecologia, 2013 Jul;172(3):713-24.
    PMID: 23183820 DOI: 10.1007/s00442-012-2529-z
    Differences in the density of conspecific tree individuals in response to environmental gradients are well documented for many tree species, but how such density differences are generated and maintained is poorly understood. We examined the segregation of six dipterocarp species among three soil types in the Pasoh tropical forest, Malaysia. We examined how individual performance and population dynamics changed across the soil types using 10-year demographic data to compare tree performance across soil types, and constructed population matrix models to analyze the population dynamics. Species showed only minor changes in mortality and juvenile growth across soil types, although recruitment differed greatly. Clear, interspecific demographic trade-offs between growth and mortality were found in all soil types. The relative trade-offs by a species did not differ substantially among the soil types. Population sizes were projected to remain stable in all soil types for all species with one exception. Our life-table response experiment demonstrated that the population dynamics of a species differed only subtly among soil types. Therefore, species with strong density differences across soil types do not necessarily differ greatly in their population dynamics across the soil types. In contrast, interspecific differences in population dynamics were large. The trade-off between mortality and growth led to a negative correlation between the contributions of mortality and growth to variations in the population growth rate (λ) and thus reduced their net contributions. Recruitment had little impact on the variation in λ. The combination of these factors resulted in little variation in λ among species.
    Matched MeSH terms: Population Dynamics
  3. Modeling fish community dynamics in the Florida Everglades: role of temperature variation
    Al-Rabai'ah HA, Koh HL, DeAngelis D, Lee HL
    Water Sci Technol, 2002;46(9):71-8.
    PMID: 12448454
    Temperature variation is an important factor in Everglade wetlands ecology. A temperature fluctuation from 17 degrees C to 32 degrees C recorded in the Everglades may have significant impact on fish dynamics. The short life cycles of some of Everglade fishes has rendered this temperature variation to have even more impacts on the ecosystem. Fish population dynamic models, which do not explicitly consider seasonal oscillations in temperature, may fail to describe the details of such a population. Hence, a model for fish in freshwater marshes of the Florida Everglades that explicitly incorporates seasonal temperature variations is developed. The model's main objective is to assess the temporal pattern of fish population and densities through time subject to temperature variations. Fish population is divided into 2 functional groups (FGs) consisting of small fishes; each group is subdivided into 5-day age classes during their life cycles. Many governing sub-modules are set directly or indirectly to be temperature dependent. Growth, fecundity, prey availability, consumption rates and mortality are examples. Several mortality sub-modules are introduced in the model, of which starvation mortality is set to be proportional to the ratio of prey needed to prey available at that particular time step. As part of the calibration process, the model is run for 50 years to ensure that fish densities do not go to extinction, while the simulation period is about 8 years. The model shows that the temperature dependent starvation mortality is an important factor that influences fish population densities. It also shows high fish population densities at some temperature ranges when this consumption need is minimum. Several sensitivity analyses involving variations in temperature terms, food resources and water levels are conducted to ascertain the relative importance of temperature dependence terms.
    Matched MeSH terms: Population Dynamics
  4. New world order. Overcrowded
    Asiaweek, 1995 Sep 29.
    PMID: 12290445
    Matched MeSH terms: Population Dynamics
  5. [Population growth and mortality decline in Southeast Asia]
    Kobayashi K
    Tonan Ajia Kenkyu, 1982 Sep;20(2):143-67.
    PMID: 12312334
    Matched MeSH terms: Population Dynamics
  6. Malaysia: population: 13.43 million Malaysians
    Data Asia, 1981 Feb;10(8):7691-2.
    PMID: 12262368
    Matched MeSH terms: Population Dynamics
  7. Fulltext Spatio-temporal variations in wheat aphid populations and their natural enemies in four agro-ecological zones of Pakistan
    Faheem M, Saeed S, Sajjad A, Wang S, Ali A
    PLoS One, 2019;14(9):e0222635.
    PMID: 31568475 DOI: 10.1371/journal.pone.0222635
    Aphids are major pests of wheat crop in Pakistan inflicting considerable economic losses. A better knowledge of landscape scale spatial distribution of aphids and their natural enemies could be used to improve integrated pest management programs. Therefore, the present study aimed to document spatio-temporal variations in populations of wheat aphids and their natural enemies in Pakistan. The 2-year survey study was carried out at ten experimental farms located in five districts of four contrasted agro-ecological zones of eastern Pakistan (Punjab area) i.e. District Chakwal in arid zone, Gujranwala in rice-cropped zone, Faisalabad in central mixed-cropped zone, and Khanewal and Multan in cotton-cropped zone. The dominant aphid species i.e. Schizaphis graminum, Rhopalosiphum padi, R. maidis and Sitobion avenae varied significantly among the five districts surveyed. The population of S. graminum was observed more abundant in arid, R. padi in rice, S. avenae in aird and rice, and R. maidis in cotton-I zones. Aphids ended their population dynamics on 25th March in central mixed-cropped zone and 12th April in other three zones. Various species of natural enemies, mainly Coccinella septumpunctata, C. undecimpunctata, Menochilus sexmaculata, Chrysoperla carnea, Syrphidae and parasitoid mummies were inconsistently observed in four agro-ecological zones. The population of C. septumpunctata, was observed more abundant in rice zone, C. undecimpunctata and C. carnea in cotton-I and arid zones, M. sexmaculata in cotton-I and II zones, Syrphidae in cotton-I zone and parasitoid mummies in rice and arid zones. There were no clear relationships between aphid and the natural enemy populations. The present study may serve as a baseline regarding distribution of wheat aphids and their natural enemies and the results provided insights for further studies on the potential top-down (natural enemies) versus bottom-up (fertilization and irrigation regimes) forces in management of wheat aphids in eastern Pakistan.
    Matched MeSH terms: Population Dynamics
  8. Fulltext Smart and Climate-Smart Agricultural Trends as Core Aspects of Smart Village Functions
    Adesipo A, Fadeyi O, Kuca K, Krejcar O, Maresova P, Selamat A, et al.
    Sensors (Basel), 2020 Oct 22;20(21).
    PMID: 33105622 DOI: 10.3390/s20215977
    Attention has shifted to the development of villages in Europe and other parts of the world with the goal of combating rural-urban migration, and moving toward self-sufficiency in rural areas. This situation has birthed the smart village idea. Smart village initiatives such as those of the European Union is motivating global efforts aimed at improving the live and livelihood of rural dwellers. These initiatives are focused on improving agricultural productivity, among other things, since most of the food we eat are grown in rural areas around the world. Nevertheless, a major challenge faced by proponents of the smart village concept is how to provide a framework for the development of the term, so that this development is tailored towards sustainability. The current work examines the level of progress of climate smart agriculture, and tries to borrow from its ideals, to develop a framework for smart village development. Given the advances in technology, agricultural development that encompasses reduction of farming losses, optimization of agricultural processes for increased yield, as well as prevention, monitoring, and early detection of plant and animal diseases, has now embraced varieties of smart sensor technologies. The implication is that the studies and results generated around the concept of climate smart agriculture can be adopted in planning of villages, and transforming them into smart villages. Hence, we argue that for effective development of the smart village framework, smart agricultural techniques must be prioritized, viz-a-viz other developmental practicalities.
    Matched MeSH terms: Population Dynamics
  9. Fulltext Southeast Asian health system challenges and responses to the 'Andaman Sea refugee crisis': A qualitative study of health-sector perspectives from Indonesia, Malaysia, Myanmar, and Thailand
    Legido-Quigley H, Leh Hoon Chuah F, Howard N
    PLoS Med, 2020 11;17(11):e1003143.
    PMID: 33170834 DOI: 10.1371/journal.pmed.1003143
    BACKGROUND: Southeast Asian countries host signficant numbers of forcibly displaced people. This study was conducted to examine how health systems in Southeast Asia have responded to the health system challenges of forced migration and refugee-related health including the health needs of populations affected by forced displacement; the health systems-level barriers and facilitators in addressing these needs; and the implications of existing health policies relating to forcibly displaced and refugee populations. This study aims to fill in the gap in knowledge by analysing how health systems are organised in Southeast Asia to address the health needs of forcibly displaced people.

    METHODS AND FINDINGS: We conducted 30 semistructured interviews with health policy-makers, health service providers, and other experts working in the United Nations (n = 6), ministries and public health (n = 5), international (n = 9) and national civil society (n = 7), and academia (n = 3) based in Indonesia (n = 6), Malaysia (n = 10), Myanmar (n = 6), and Thailand (n = 8). Data were analysed thematically using deductive and inductive coding. Interviewees described the cumulative nature of health risks at each migratory phase. Perceived barriers to addressing migrants' cumulative health needs were primarily financial, juridico-political, and sociocultural, whereas key facilitators were many health workers' humanitarian stance and positive national commitment to pursuing universal health coverage (UHC). Across all countries, financial constraints were identified as the main challenges in addressing the comprehensive health needs of refugees and asylum seekers. Participants recommended regional and multisectoral approaches led by national governments, recognising refugee and asylum-seeker contributions, and promoting inclusion and livelihoods. Main study limitations included that we were not able to include migrant voices or those professionals not already interested in migrants.

    CONCLUSIONS: To our knowledge, this is one of the first qualitative studies to investigate the health concerns and barriers to access among migrants experiencing forced displacement, particularly refugees and asylum seekers, in Southeast Asia. Findings provide practical new insights with implications for informing policy and practice. Overall, sociopolitical inclusion of forcibly displaced populations remains difficult in these four countries despite their significant contributions to host-country economies.

    Matched MeSH terms: Population Dynamics
  10. Community fluctuations and local extinction in a planktonic food web
    Segura AM, Calliari D, Lan BL, Fort H, Widdicombe CE, Harmer R, et al.
    Ecol Lett, 2017 04;20(4):471-476.
    PMID: 28239940 DOI: 10.1111/ele.12749
    Determining statistical patterns irrespective of interacting agents (i.e. macroecology) is useful to explore the mechanisms driving population fluctuations and extinctions in natural food webs. Here, we tested four predictions of a neutral model on the distribution of community fluctuations (CF) and the distributions of persistence times (APT). Novel predictions for the food web were generated by combining (1) body size-density scaling, (2) Taylor's law and (3) low efficiency of trophic transference. Predictions were evaluated on an exceptional data set of plankton with 15 years of weekly samples encompassing c. 250 planktonic species from three trophic levels, sampled in the western English Channel. Highly symmetric non-Gaussian distributions of CF support zero-sum dynamics. Variability in CF decreased while a change from an exponential to a power law distribution of APT from basal to upper trophic positions was detected. Results suggest a predictable but profound effect of trophic position on fluctuations and extinction in natural communities.
    Matched MeSH terms: Population Dynamics
  11. Fulltext Temporal changes in the abundance of Musca domestica Linn (Diptera: Muscidae) in poultry farms in Penang, Malaysia
    Jin BL, Jaal Z
    Trop Biomed, 2009 Aug;26(2):140-8.
    PMID: 19901900 MyJurnal
    Changes in the abundance of the house fly, Musca domestica, was studied for a period of one year in two poultry farms in Penang, Malaysia: one in Balik Pulau, located in Penang island, and the other in Juru, located on mainland Penang. The sampling of house flies were carried out from March 2007 to April 2008 using the Scudder grill, and the correlation with meteorological conditions particularly rainfall, relative humidity and temperature were observed. In Balik Pulau, the fly abundance showed an inverse relationship to relative humidity and total rainfall. However, no significant correlations were found between the abundance of flies and the above mentioned climatic factors. In contrast, the occurrence of flies in Juru showed strong correlation indices with relative humidity (r=0.803, p<0.05) and total rainfall (r=0.731, p<0.05). Temperature had no significant effect on the abundance of flies in both poultry farms due to imperceptible changes in monthly temperature.
    Matched MeSH terms: Population Dynamics
  12. Fulltext Population analysis of Aedes albopictus (Skuse) (Diptera:Culicidae) under uncontrolled laboratory conditions
    Nur Aida H, Abu Hassan A, Nurita AT, Che Salmah MR, Norasmah B
    Trop Biomed, 2008 Aug;25(2):117-25.
    PMID: 18948882
    A semi laboratory experiment using 3 cohorts of Aedes albopictus adults was performed to obtain age-specific mortality and fecundity information and to derive statistical estimates of some population growth parameters. Life expectancy was calculated for both males and females. The following population parameters were estimated: intrinsic rate of increase (rm= 0.21), net reproductive (replacement) rate (Ro= 68.70), age at mean cohort reproduction (To=10.55 days), birth rate (B=0.23), death rate (D=0.02) and generation time (G=20.14 days). The high rm/B (0.91) and B/D (11.50) ratios indicated the high colonizing ability of Ae. albopictus in nature.
    Matched MeSH terms: Population Dynamics
  13. Gender and risk of depression in Saudi Arabia, a systematic review and meta-analysis
    Alibrahim OA, Al-Sadat N, Elawad NA
    J Public Health Afr, 2010 Sep 01;1(1):e7.
    PMID: 28299041 DOI: 10.4081/jphia.2010.e7
    Depression is one of the leading causes of mortality and morbidity worldwide. In the year 2000 depression accounted for 4.4% of the global disability adjusted life years (DALYs). The Kingdom of Saudi Arabia (KSA) has a population of 28 million people and is one of the countries experiencing demographic transition in its population structure. Improvements in socioeconomic status have been shown to be associated with increased chronic diseases including chronic mental diseases like depression, but still there is no comprehensive review summarizing the various reports currently existing in the literature. Although individual studies within Saudi Arabia have reported prevalence rates and risks, the quality of such studies need to be subjected to rigorous assessment and their findings pooled to give combined weighted evidence that will provide basis for targeted intervention. Pooled risks have the advantage of adjusting inherent variations within sampled populations and therefore providing more reliable estimates even though there are concerns about possible magnification of smaller individual risks.
    Matched MeSH terms: Population Dynamics
  14. The decline of fertility in Peninsular Malaysia
    Hirschman C, Fernandez D
    Genus, 1980 Jan-Jun;36(1/2):93-127.
    PMID: 12263330
    Matched MeSH terms: Population Dynamics
  15. Asia educates to brake the population juggernaut
    Friedman B
    Soc Welfare (India), 1974 Dec 5;21(9):3.
    PMID: 12257917
    Matched MeSH terms: Population Dynamics
  16. Semai Senoi fertility and population dynamics: Two-census method
    Fix AG
    Am J Hum Biol, 1989;1(4):463-469.
    PMID: 28514113 DOI: 10.1002/ajhb.1310010409
    The fertility and parameters of population growth of the Semai Senoi of Malaysia are studied by using a two-census method based on nonstable population theory. Semai fertility is shown to be moderately high; female completed fertility is 7.42 children and the crude birth rate is greater than 0.050. Previous estimates of Semai mortality rates are also moderately high but are insufficient to balance birth; thus, the overall rate of growth is presently nearly 2%. Compared with an earlier description of the pre-1969 Semai population, fertility has increased markedly leading to a nearly threefold increase in the annual growth rate.
    Matched MeSH terms: Population Dynamics
  17. Application of Remote Sensing on the Dispersion and Concentration of Total Suspended Sediment Offshore Langat Estuary
    Othman A.K., Othman J., Sharifah Mastura S.A.
    Sains Malaysiana, 2004;33.
    This paper focuses on Langat River basin which is experiencing fast pace land use changes and accelerated soil erosion associated with land clearing and earthwork activities. Land use changes detected from Landsat imageries from 1989-1999 show that urban expansion is the most active, i.e. recording an expansion of 180% over that time period. The major land use reduction is the tropical dipterocarp rainforest located along the upper catchment of the Langat River and the mangrove forest found along Kuala Langat in the west. The 11% decline in the trend of the forest over that decade is anticipated to contribute in the near future. Results from logistic regression on the casual factors of rapid land use changes are attributed to three significant variables namely transport accessibility, population dynamics and agriculture. The eroded material due to land use changes enters into the Langat River systems as suspended sediments and contributed as non point source of pollution. Some finer sediment is being discharged offshore forming sediment plumes at the river estuary. Sediment plumes detected by Landsat TM imageries were analysed. It is found that the dispersion was not extensive and generally the suspended solids existed at low concentration (varying from 10-50 mg/l). This result is unexpected considering the rapid land use and land cover change that is occurring within the basins. These are mainly due to the loss of sediments during flooding into flood plain and active dredging of the river channels.
    Matched MeSH terms: Population Dynamics
  18. Climate change and declining fertility rate in Malaysia: the possible connexions
    Jegasothy R, Sengupta P, Dutta S, Jeganathan R
    J Basic Clin Physiol Pharmacol, 2020 Dec 14;32(5):911-924.
    PMID: 33580644 DOI: 10.1515/jbcpp-2020-0236
    Climate change is an incessant global phenomenon and has turned contentious in the present century. Malaysia, a developing Asian country, has also undergone significant vicissitudes in climate, which has been projected with significant deviations in forthcoming decades. As per the available studies, climate changes may impact on the fertility, either via direct effects on the gonadal functions and neuroendocrine regulations or via several indirect effects on health, socioeconomic status, demeaning the quality of food and water. Malaysia is already observing a declining trend in the Total fertility rate (TFR) over the past few decades and is currently recorded below the replacement level of 2.1 which is insufficient to replace the present population. Moreover, climate changes reportedly play a role in the emergence and cessation of various infectious diseases. Besides its immediate effects, the long-term effects on health and fertility await to be unveiled. Despite the huge magnitude of the repercussion of climate changes in Malaysia, research that can explain the exact cause of the present reduction in fertility parameters in Malaysia or any measures to preserve the national population is surprisingly very scarce. Thus, the present review aims to elucidate the possible missing links by which climate changes are impairing fertility status in Malaysia.
    Matched MeSH terms: Population Dynamics
  19. Monitoring tigers with confidence
    Linkie M, Guillera-Arroita G, Smith J, Rayan DM
    Integr Zool, 2010 Dec;5(4):342-350.
    PMID: 21392352 DOI: 10.1111/j.1749-4877.2010.00215.x
    With only 5% of the world's wild tigers (Panthera tigris Linnaeus, 1758) remaining since the last century, conservationists urgently need to know whether or not the management strategies currently being employed are effectively protecting these tigers. This knowledge is contingent on the ability to reliably monitor tiger populations, or subsets, over space and time. In the this paper, we focus on the 2 seminal methodologies (camera trap and occupancy surveys) that have enabled the monitoring of tiger populations with greater confidence. Specifically, we: (i) describe their statistical theory and application in the field; (ii) discuss issues associated with their survey designs and state variable modeling; and, (iii) discuss their future directions. These methods have had an unprecedented influence on increasing statistical rigor within tiger surveys and, also, surveys of other carnivore species. Nevertheless, only 2 published camera trap studies have gone beyond single baseline assessments and actually monitored population trends. For low density tiger populations (e.g. <1 adult tiger/100 km(2)) obtaining sufficient precision for state variable estimates from camera trapping remains a challenge because of insufficient detection probabilities and/or sample sizes. Occupancy surveys have overcome this problem by redefining the sampling unit (e.g. grid cells and not individual tigers). Current research is focusing on developing spatially explicit capture-mark-recapture models and estimating abundance indices from landscape-scale occupancy surveys, as well as the use of genetic information for identifying and monitoring tigers. The widespread application of these monitoring methods in the field now enables complementary studies on the impact of the different threats to tiger populations and their response to varying management intervention.
    Matched MeSH terms: Population Dynamics
  20. A novel mechanism measurement of predator interference in predator-prey models
    Alebraheem J, Abu-Hassan Y
    J Math Biol, 2023 Apr 27;86(5):84.
    PMID: 37103566 DOI: 10.1007/s00285-023-01914-8
    A characteristic of ecosystems is the existence of manifold of independencies which are highly complex. Various mathematical models have made considerable contributions in gaining a better understanding of the predator-prey interactions. The main components of any predator-prey models are, firstly, how the different population classes grow and secondly, how the prey and predator interacts. In this paper, the two populations' growth rates obey the logistic law and the carrying capacity of the predator depends on the available number of prey are considered. Our aim is to clarify the relationship between models and Holling types functional and numerical responses in order to gain insights into predator interferences and to answer an important question how competition is carried out. We consider a predator-prey model and a two-predator one-prey model to explain the idea. The novel approach is explained for the mechanism measurement of predator interference through depending on numerical response. Our approach gives good correspondence between an important real data and computer simulations.
    Matched MeSH terms: Population Dynamics
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