Displaying publications 81 - 100 of 151 in total

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  1. Luskin MS, Albert WR, Tobler MW
    Nat Commun, 2017 12 05;8(1):1783.
    PMID: 29208916 DOI: 10.1038/s41467-017-01656-4
    The continuing development of improved capture-recapture (CR) modeling techniques used to study apex predators has also limited robust temporal and cross-site analyses due to different methods employed. We develop an approach to standardize older non-spatial CR and newer spatial CR density estimates and examine trends for critically endangered Sumatran tigers (Panthera tigris sumatrae) using a meta-regression of 17 existing densities and new estimates from our own fieldwork. We find that tiger densities were 47% higher in primary versus degraded forests and, unexpectedly, increased 4.9% per yr from 1996 to 2014, likely indicating a recovery from earlier poaching. However, while tiger numbers may have temporarily risen, the total potential island-wide population declined by 16.6% from 2000 to 2012 due to forest loss and degradation and subpopulations are significantly more fragmented. Thus, despite increasing densities in smaller parks, we conclude that there are only two robust populations left with >30 breeding females, indicating Sumatran tigers still face a high risk of extinction unless deforestation can be controlled.
    Matched MeSH terms: Population Density
  2. von Seth J, Dussex N, Díez-Del-Molino D, van der Valk T, Kutschera VE, Kierczak M, et al.
    Nat Commun, 2021 Apr 26;12(1):2393.
    PMID: 33896938 DOI: 10.1038/s41467-021-22386-8
    Small populations are often exposed to high inbreeding and mutational load that can increase the risk of extinction. The Sumatran rhinoceros was widespread in Southeast Asia, but is now restricted to small and isolated populations on Sumatra and Borneo, and most likely extinct on the Malay Peninsula. Here, we analyse 5 historical and 16 modern genomes from these populations to investigate the genomic consequences of the recent decline, such as increased inbreeding and mutational load. We find that the Malay Peninsula population experienced increased inbreeding shortly before extirpation, which possibly was accompanied by purging. The populations on Sumatra and Borneo instead show low inbreeding, but high mutational load. The currently small population sizes may thus in the near future lead to inbreeding depression. Moreover, we find little evidence for differences in local adaptation among populations, suggesting that future inbreeding depression could potentially be mitigated by assisted gene flow among populations.
    Matched MeSH terms: Population Density
  3. MacNeil MA, Chapman DD, Heupel M, Simpfendorfer CA, Heithaus M, Meekan M, et al.
    Nature, 2020 07;583(7818):801-806.
    PMID: 32699418 DOI: 10.1038/s41586-020-2519-y
    Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats3. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.
    Matched MeSH terms: Population Density
  4. Quek SP, Davies SJ, Ashton PS, Itino T, Pierce NE
    Mol Ecol, 2007 May;16(10):2045-62.
    PMID: 17498231
    We investigate the geographical and historical context of diversification in a complex of mutualistic Crematogaster ants living in Macaranga trees in the equatorial rain forests of Southeast Asia. Using mitochondrial DNA from 433 ant colonies collected from 32 locations spanning Borneo, Malaya and Sumatra, we infer branching relationships, patterns of genetic diversity and population history. We reconstruct a time frame for the ants' diversification and demographic expansions, and identify areas that might have been refugia or centres of diversification. Seventeen operational lineages are identified, most of which can be distinguished by host preference and geographical range. The ants first diversified 16-20 Ma, not long after the onset of the everwet forests in Sundaland, and achieved most of their taxonomic diversity during the Pliocene. Pleistocene demographic expansions are inferred for several of the younger lineages. Phylogenetic relationships suggest a Bornean cradle and major axis of diversification. Taxonomic diversity tends to be associated with mountain ranges; in Borneo, it is greatest in the Crocker Range of Sabah and concentrated also in other parts of the northern northwest coast. Within-lineage genetic diversity in Malaya and Sumatra tends to also coincide with mountain ranges. A series of disjunct and restricted distributions spanning northern northwest Borneo and the major mountain ranges of Malaya and Sumatra, seen in three pairs of sister lineages, further suggests that these regions were rain-forest refuges during drier climatic phases of the Pleistocene. Results are discussed in the context of the history of Sundaland's rain forests.
    Matched MeSH terms: Population Density
  5. García-Berro A, Talla V, Vila R, Wai HK, Shipilina D, Chan KG, et al.
    Mol Ecol, 2023 Feb;32(3):560-574.
    PMID: 36336800 DOI: 10.1111/mec.16770
    Migration is typically associated with risk and uncertainty at the population level, but little is known about its cost-benefit trade-offs at the species level. Migratory insects in particular often exhibit strong demographic fluctuations due to local bottlenecks and outbreaks. Here, we use genomic data to investigate levels of heterozygosity and long-term population size dynamics in migratory insects, as an alternative to classical local and short-term approaches such as regional field monitoring. We analyse whole-genome sequences from 97 Lepidoptera species and show that individuals of migratory species have significantly higher levels of genome-wide heterozygosity, a proxy for effective population size, than do nonmigratory species. Also, we contribute whole-genome data for one of the most emblematic insect migratory species, the painted lady butterfly (Vanessa cardui), sampled across its worldwide distributional range. This species exhibits one of the highest levels of genomic heterozygosity described in Lepidoptera (2.95 ± 0.15%). Coalescent modelling (PSMC) shows historical demographic stability in V. cardui, and high effective population size estimates of 2-20 million individuals 10,000 years ago. The study reveals that the high risks associated with migration and local environmental fluctuations do not seem to decrease overall genetic diversity and demographic stability in migratory Lepidoptera. We propose a "compensatory" demographic model for migratory r-strategist organisms in which local bottlenecks are counterbalanced by reproductive success elsewhere within their typically large distributional ranges. Our findings highlight that the boundaries of populations are substantially different for sedentary and migratory insects, and that, in the latter, local and even regional field monitoring results may not reflect whole population dynamics. Genomic diversity patterns may elucidate key aspects of an insect's migratory nature and population dynamics at large spatiotemporal scales.
    Matched MeSH terms: Population Density
  6. Deepak AS, Ong JY, Choon D, Lee CK, Chiu CK, Chan C, et al.
    Malays Orthop J, 2017 Mar;11(1):41-46.
    PMID: 28435573 MyJurnal DOI: 10.5704/MOJ.1703.018
    INTRODUCTION: There is no large population size study on school screening for scoliosis in Malaysia. This study is aimed to determine the prevalence rate and positive predictive value (PPV) of screening programme for adolescent idiopathic scoliosis.

    MATERIALS AND METHODS: A total of 8966 voluntary school students aged 13-15 years old were recruited for scoliosis screening. Screening was done by measuring the angle of trunk rotation (ATR) on forward bending test (FBT) using a scoliometer. ATR of 5 degrees or more was considered positive. Positively screened students had standard radiographs done for measurement of the Cobb angle. Cobb angle of >10° was used to diagnose scoliosis. The percentage of radiological assessment referral, prevalence rate and PPV of scoliosis were then calculated.

    RESULTS: Percentage of radiological assessment referral (ATR >5°) was 4.2% (182/4381) for male and 5.0% (228/4585) for female. Only 38.0% of those with ATR >5° presented for further radiological assessment. The adjusted prevalence rate was 2.55% for Cobb angle >10°, 0.59% for >20° and 0.12% for >40°. The PPV is 55.8% for Cobb angle >10°, 12.8% for >20° and 2.6% for > 40°.

    CONCLUSIONS: This is the largest study of school scoliosis screening in Malaysia. The prevalence rate of scoliosis was 2.55%. The positive predictive value was 55.8%, which is adequate to suggest that the school scoliosis screening programme did play a role in early detection of scoliosis. However, a cost effectiveness analysis will be needed to firmly determine its efficacy.

    Matched MeSH terms: Population Density
  7. Arshat H, Tey Nai Peng
    Malays J Reprod Health, 1988 Jun;6(1):23-46.
    PMID: 12281592
    Matched MeSH terms: Population Density
  8. Kabir MJ, Hassanzadeh-Rostami Z, Ashrafian Amiri H, Nasrollapour Shirvani SD, Keshavarzi A, Hosseini S
    Malays Fam Physician, 2019;14(3):28-36.
    PMID: 32175038
    Background and objective: A successful family physician program needs ongoing and full cooperation between people and the organizations in charge. Ensuring the satisfaction of family physicians through improvement of the underlying factors could motivate them to provide high-quality services. This study aimed to determine the family physicians' satisfaction level with the factors affecting the dynamism of the urban family physicians program in the Fars and Mazandaran provinces of Iran.

    Method: This cross-sectional study was carried out in urban areas in the Fars and Mazandaran provinces in 2016. The sample consisted of 143 and 96 family physicians, respectively, in Fars and Mazandaran provinces and was selected using the stratified random sampling method. Data were collected using a questionnaire and included both sociodemographic variables and factors assessing the family physicians' satisfaction levels. Each factor was scored based on a Likert scale from 0 to 5 points, and any satisfaction level higher than 3 out of 5 was equated with being satisfied.

    Results: The overall satisfaction levels among family physicians in Fars and Mazandaran provinces were 2.77±0.53 and 3.37±0.56, respectively, revealing a statistically significant difference between provinces (p<0.001). Moreover, the mean satisfaction scores for the performances of healthcare centers, insurance companies, specialists, healthcare workers, and the population covered were 2.78±0.1, 2.54±0.9, 2.52±0.8, 4.24±0.07, and 2.96±0.8, respectively. The family physicians' levels of satisfaction were significantly correlated with population size (p=0.02, r= -0.106), and willingness to stay in an urban family physician program (p<0.001, r= +0.398).

    Conclusion: This study revealed that family physicians exhibited a low level of satisfaction with the urban family physician program. Given the direct association between family physicians' satisfaction levels and retention in the program, it is expected that family physicians will no longer stay in the program, and it is likely to have subsequent executive problems.

    Matched MeSH terms: Population Density
  9. Meftahuddin Tarip, Jamsiah Mustafa
    MyJurnal
    The aim of this study is to describe the epidemiological features of HFMD outbreak in the Hulu Langat District in 2000. Until November 2000, a total of 60 cases were reported and the worst ever reported to the previous years. The mean age of patients was 3.9; 5.8 years with majority of the cases aged between 1 to 4 years old (53.8 per 100,000 of population), male gender (8.3 per 100,000 of populations), and were of Chinese (12.2 per 11 100,000 of populations) and Malay ethnicity (7.2 per 100.000 of populations). All cases were uncomplicated cases and were diagnosed clinically. Most of the notified cases were front the government facilities, which are 44 cases (73.3%). Thirty-five (35) cases (58.4%) were treated as outpatient and 25 cases (41.6%) as in patients (p>0,05). Only 7 cases (11.7%) have history of contact with HFMD patients. The notified cases were mainly from the densely populated areas which were Cheras, Kajang and Ampang. No differences were noted between HFMD cases which have been breasfed for less than 6 month or more, and twenty nine (29) cases (48.3 %) had completed the immunization schedule. In conclusion, the recent emergence of HFMD brings a new challenge, which have to be faced in the prevention and surveillance activities of public health problems in the district.
    Study site: Notified cases from Klinik Kesihatan, hospital, private clinics, Ulu Langat, Selangor, Malaysia
    Matched MeSH terms: Population Density
  10. Mohamed Nor N, Ross H, Thinng WBK, Abdul Ghani J, Hassan N, Baharom N
    MyJurnal
    Introduction: In respond to the World Health Assembly global NCD target of 30% reduction in the prevalence of adult tobacco use by 2025, Malaysian government called for lowering its smoking prevalence to 15% by 2025. In addition, moving towards the endgame target of less than 5% smoking prevalence in 2045. Methods: Malaysia Abridged SimSmoke model, a simulation model uses specific policy parameters, the most recent smoking prevalence, and population size for Malaysia is developed to estimates and access the impact of MPOWER policies in achieving the targets. Results: The 15% prevalence rate in 2025 can be achieved if the Malaysian government increase tobacco excise tax to 72% of the retail price, implement and enforce comprehensive smoke-free air policies, ban all forms of advertising/promotions and run intensive mass media campaigns. Such approach would reduce the number of smokers by about 2.6 million, averting almost 1.3 million premature deaths in the long term. The tobacco endgame target of less than 5% smoking prevalence by 2045 is achievable if the excise tax is further increased to 86.5% of the retail price while all other tobacco control policies are kept at the enhanced level. Conclusions: Both the targeted smoking prevalence are a realistic proposition if the proposed measures are fully implemented. It requires a whole government approach with the MOH as a leading agency driving the process. It is important to monitor both the compliance with the new measures and smoking prevalence to make sure that Malaysia is on track in achieving its targets.
    Matched MeSH terms: Population Density
  11. Farhana Johar, Julies Bong Shu Ai, Fuaada Mohd Siam
    MATEMATIKA, 2020;36(3):235-250.
    MyJurnal
    A new topic of Zero Energy Building (ZEB) is getting famous in research area
    because of its goal of reaching zero carbon emission and low building cost. Renewable
    energy system is one of the ideas to achieve the objective of ZEB. Genetic Algorithm (GA)
    is widely used in many research areas due to its capability to escape from a local minimal
    to obtain a better solution. In our study, GA is chosen in sizing optimization of the
    number of photovoltaic, wind turbine and battery of a hybrid photovoltaic-wind-battery
    system. The aim is to minimize the total annual cost (TAC) of the hybrid energy system
    towards the low cost concept of ZEB. Two GA parameters, which are generation number
    and population size, have been analysed and optimized in order to meet the minimum
    TAC. The results show that the GA is efficient in minimizing cost function of a hybrid
    photovoltaic-wind-battery system with its robustness property.
    Matched MeSH terms: Population Density
  12. Aziz S, Aidil RM, Nisfariza MN, Ngui R, Lim YA, Yusoff WS, et al.
    J Vector Borne Dis, 2014 Jun;51(2):91-6.
    PMID: 24947215
    Dengue fever (DF) is a major vector-borne disease in Malaysia. The incidences of DF in Malaysia are caused by viruses transmitted through the bites of infected female Aedes albopictus and Ae. aegypti mosquitoes. This study aims to establish the spatial density of mosquito population or breteau index (BI) in the areas of Kuala Lumpur using geographic information system (GIS), remote sensing (RS) and spatial statistical tools.
    Matched MeSH terms: Population Density
  13. Saifur RG, Hassan AA, Dieng H, Salmah MR, Saad AR, Satho T
    J Am Mosq Control Assoc, 2013 Mar;29(1):33-43.
    PMID: 23687853
    We studied the diversity of Aedes breeding sites in various urban, suburban, and rural areas over time between February 2009 and February 2010 in the dengue endemic areas of Penang Island, Malaysia. We categorized the breeding sites and efficiency, and identified the key breeding containers. Among the 3 areas, the rural areas produced the highest container index (55), followed by suburban (42) and urban (32) areas. The numbers of key premises and containers were significantly higher (P < 0.000) in rural areas. The class 1 containers were identified as the key containers with higher productivity and efficiency, although class 2 and class 4 are the highest in numbers. Aedes aegypti immatures were found mostly in drums, water reservoirs, and polyethylene sheets, while mixed breeding was more common in buckets and empty paint cans in urban and suburban areas. Aedes albopictus was found mainly in miscellaneous containers such as drums, empty paint cans, and covers in all areas. The main potential containers indoors were drums, water reservoirs, and empty paint cans, and containers outdoors included empty paint cans, drums, and polyethylene sheets.
    Matched MeSH terms: Population Density
  14. Saifur RG, Hassan AA, Dieng H, Ahmad H, Salmah MR, Satho T, et al.
    J Am Mosq Control Assoc, 2012 Jun;28(2):84-92.
    PMID: 22894118
    It is important to obtain frequent measurements of the abundance, distribution, and seasonality of mosquito vectors to determine the risk of disease transmission. The number of cases of dengue infection has increased in recent years on Penang Island, Malaysia, with recurring epidemics. However, ongoing control attempts are being critically hampered by the lack of up-to-date information regarding the vectors. To overcome this problem, we examined the current situation and distribution of dengue vectors on the island. Residences throughout the urban, suburban, and rural areas were inspected through wet and dry seasons between February 2009 and February 2010. Two vectors were encountered in the survey, with Aedes aegypti present in especially high numbers mostly in urban areas. Similar observations were noted for Ae. albopictus in rural areas. The former species was more abundant in outdoor containers, while the latter showed almost equivalent abundance both outdoors and indoors. The dengue virus was active in both urban and rural areas, and the number of cases of infection was higher in areas where Ae. aegypti was predominant. The abundance of immature Ae. albopictus was positively correlated with rainfall (r2 = 0.461; P < 0.05), but this was not the case for Ae. aegypti. For both species, the size of immature populations tended to increase with increasing intensity of rain, but heavy rains resulted in population loss. In addition to updating data regarding the larval habitats and locations (outdoors and indoors), this study highlighted the importance of spatial vector control stratification, which has the potential to reduce costs in control programs.
    Matched MeSH terms: Population Density
  15. Marcela P, Hassan AA, Hamdan A, Dieng H, Kumara TK
    J Am Mosq Control Assoc, 2015 Dec;31(4):313-20.
    PMID: 26675452 DOI: 10.2987/moco-31-04-313-320.1
    Mating behavior between Aedes aegypti and Ae. albopictus, established colony strains were examined under laboratory conditions (30-cm(3) screened cages) for 5 consecutive days. The effect of selected male densities (30, 20, 10) and female density (20) on the number of swarming, mating pairs, eggs produced, and inseminated females were evaluated. Male densities significantly increased swarming behavior, mating pairs, and egg production of heterospecific females, but female insemination was reduced. Aedes aegypti males mate more readily with heterospecific females than do Ae. albopictus males. The current study suggests that Ae. aegypti males were not species-specific in mating, and if released into the field as practiced in genetically modified mosquito techniques, they may mate with both Ae. aegypti and Ae. albopictus females, hence reducing populations of both species by producing infertile eggs.
    Matched MeSH terms: Population Density
  16. Fukue Y, Kado T, Lee SL, Ng KK, Muhammad N, Tsumura Y
    J Plant Res, 2007 May;120(3):413-20.
    PMID: 17387430
    Pristine tropical rainforests in Southeast Asia have rich species diversity and are important habitats for many plant species. However, the extent of these forests has declined in recent decades and they have become fragmented due to human activities. These developments may reduce the genetic diversity of species within them and, consequently, the species' ability to adapt to environmental changes. Our objective in the study presented here was to clarify the effect of tree density on the genetic diversity and gene flow patterns of Shorea leprosula Miq. populations in Peninsular Malaysia. For this purpose, we related genetic diversity and pollen flow parameters of seedling populations in study plots to the density of mature trees in their vicinity. The results show that gene diversity and allelic richness were not significantly correlated to the mature tree density. However, the number of rare alleles among the seedlings and the selfing rates of the mother trees were negatively correlated with the density of the adult trees. Furthermore, in a population with high mature tree density pollination distances were frequently <200 m, but in populations with low adult tree density the distances were longer. These findings suggest that the density of flowering trees affects selfing rates, gene flow and, thus, the genetic diversity of S. leprosula populations. We also found an individual S. leprosula tree with a unique reproductive system, probably apomictic, mating system.
    Matched MeSH terms: Population Density
  17. Foley DH, Rueda LM, Wilkerson RC
    J Med Entomol, 2007 Jul;44(4):554-67.
    PMID: 17695008
    To advance our limited knowledge of global mosquito biogeography, we analyzed country occurrence records from the Systematic Catalog of the Culicidae (http://www.mosquitocatalog. org/main.asp), and we present world maps of species richness and endemism. A latitudinal biodiversity gradient was observed, with species richness increasing toward the equator. A linear log-log species (y)-area (x) relationship (SAR) was found that we used to compare observed and expected species densities for each country. Brazil, Indonesia, Malaysia, and Thailand had the highest numbers of species, and Brazil also had the highest taxonomic output and number of type locations. Brazil, Australia, the Philippines, and Indonesia had the highest numbers of endemic species, but excluding small island countries, Panama, French Guiana, Malaysia, and Costa Rica had the highest densities of total species and endemic species. Globally, 50% of mosquito species are endemic. Island countries had higher total number of species and higher number of endemic species than mainland countries of similar size, but the slope of the SAR was similar for island and mainland countries. Islands also had higher numbers of publications and type locations, possibly due to greater sampling effort and/or species endemism on islands. The taxonomic output was lowest for some countries in Africa and the Middle East. A consideration of country estimates of past sampling effort and species richness and endemism is proposed to guide mosquito biodiversity surveys. For species groups, we show that the number of species of Anopheles subgenus Anopheles varies with those of subgenus Cellia in a consistent manner between countries depending on the region. This pattern is discussed in relation to hypotheses about the historical biogeography and ecology of this medically important genus. Spatial analysis of country species records offers new insight into global patterns of mosquito biodiversity and survey history.
    Matched MeSH terms: Population Density*
  18. Ong SQ, Ahmad H, Jaal Z, Rus A, Fadzlah FH
    J Med Entomol, 2017 Jan;54(1):24-29.
    PMID: 28082628 DOI: 10.1093/jme/tjw140
    Determining the control threshold for a pest is common prior to initiating a pest control program; however, previous studies related to the house fly control threshold for a poultry farm are insufficient for determining such a threshold. This study aimed to predict the population changes of house fly population by comparing the intrinsic rate of increase (rm) for different house fly densities in a simulated system. This study first defined the knee points of a known population growth curve as a control threshold by comparing the rm of five densities of house flies in a simulated condition. Later, to understand the interactions between the larval and adult populations, the correlation between larval and adult capacity rate (rc) was studied. The rm values of 300- and 500-fly densities were significantly higher compared with the rm values at densities of 50 and 100 flies. This result indicated their representative indices as candidates for a control threshold. The rc of larval and adult populations were negatively correlated with densities of fewer than 300 flies; this implicated adult populations with fewer than 300 flies as declining while the larval population was growing; therefore, control approaches should focus on the immature stages. The results in the present study suggest a control threshold for house fly populations. Future works should focus on calibrating the threshold indices in field conditions.
    Matched MeSH terms: Population Density
  19. Arai T, Chino N, Zulkifli SZ, Ismail A
    J Fish Biol, 2012 Mar;80(3):692-7.
    PMID: 22380562 DOI: 10.1111/j.1095-8649.2011.03154.x
    Previous studies indicated that a tropical freshwater eel Anguilla bicolor bicolor occurs in Africa, India, Sri Lanka, Bangladesh, Myanmar, Indonesia and Australia, but an intensive survey has indicated an extended distribution range for the species into Peninsular Malaysia. Thus, A. b. bicolor is a native subspecies of Malaysia.
    Matched MeSH terms: Population Density
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