291 research outputs found

    Evaluating the spatial transferability and temporal repeatability of remote sensing-based lake water quality retrieval algorithms at the European scale:a meta-analysis approach

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    Many studies have shown the considerable potential for the application of remote-sensing-based methods for deriving estimates of lake water quality. However, the reliable application of these methods across time and space is complicated by the diversity of lake types, sensor configuration, and the multitude of different algorithms proposed. This study tested one operational and 46 empirical algorithms sourced from the peer-reviewed literature that have individually shown potential for estimating lake water quality properties in the form of chlorophyll-a (algal biomass) and Secchi disc depth (SDD) (water transparency) in independent studies. Nearly half (19) of the algorithms were unsuitable for use with the remote-sensing data available for this study. The remaining 28 were assessed using the Terra/Aqua satellite archive to identify the best performing algorithms in terms of accuracy and transferability within the period 2001–2004 in four test lakes, namely Vänern, Vättern, Geneva, and Balaton. These lakes represent the broad continuum of large European lake types, varying in terms of eco-region (latitude/longitude and altitude), morphology, mixing regime, and trophic status. All algorithms were tested for each lake separately and combined to assess the degree of their applicability in ecologically different sites. None of the algorithms assessed in this study exhibited promise when all four lakes were combined into a single data set and most algorithms performed poorly even for specific lake types. A chlorophyll-a retrieval algorithm originally developed for eutrophic lakes showed the most promising results (R2 = 0.59) in oligotrophic lakes. Two SDD retrieval algorithms, one originally developed for turbid lakes and the other for lakes with various characteristics, exhibited promising results in relatively less turbid lakes (R2 = 0.62 and 0.76, respectively). The results presented here highlight the complexity associated with remotely sensed lake water quality estimates and the high degree of uncertainty due to various limitations, including the lake water optical properties and the choice of methods

    Report of boys and girls clubs of Oklahoma 1914

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    The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

    Exhibits: Boys and girls demonstration clubs

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    The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

    The testis and epididymis are productively infected by SIV and SHIV in juvenile macaques during the post-acute stage of infection

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    BACKGROUND: Little is known about the progression and pathogenesis of HIV-1 infection within the male genital tract (MGT), particularly during the early stages of infection. RESULTS: To study HIV pathogenesis in the testis and epididymis, 12 juvenile monkeys (Macacca nemestrina, 4–4.5 years old) were infected with Simian Immunodeficiency Virus mac 251 (SIV(mac251)) (n = 6) or Simian/Human Immunodeficiency Virus (SHIV(mn229)) (n = 6). Testes and epididymides were collected and examined by light microscopy and electron microscopy, at weeks 11–13 (SHIV) and 23 (SIV) following infection. Differences were found in the maturation status of the MGT of the monkeys, ranging from prepubertal (lacking post-meiotic germ cells) to post-pubertal (having mature sperm in the epididymal duct). Variable levels of viral RNA were identified in the lymph node, epididymis and testis following infection with both SHIV(mn229 )and SIV(mac251). Viral protein was detected via immunofluorescence histochemistry using specific antibodies to SIV (anti-gp41) and HIV-1 (capsid/p24) protein. SIV and SHIV infected macrophages, potentially dendritic cells and T cells in the testicular interstitial tissue were identified by co-localisation studies using antibodies to CD68, DC-SIGN, αβTCR. Infection of spermatogonia, but not more mature spermatogenic cells, was also observed. Leukocytic infiltrates were observed within the epididymal stroma of the infected animals. CONCLUSION: These data show that the testis and epididymis of juvenile macaques are a target for SIV and SHIV during the post-acute stage of infection and represent a potential model for studying HIV-1 pathogenesis and its effect on spermatogenesis and the MGT in general

    Redefining the "carrier" state for foot-and-mouth disease from the dynamics of virus persistence in endemically affected cattle populations

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    The foot-and-mouth disease virus (FMDV) “carrier” state was defined by van Bekkum in 1959. It was based on the recovery of infectious virus 28 days or more post infection and has been a useful construct for experimental studies. Using historic data from 1,107 cattle, collected as part of a population based study of endemic FMD in 2000, we developed a mixed effects logistic regression model to predict the probability of recovering viable FMDV by probang and culture, conditional on the animal’s age and time since last reported outbreak. We constructed a second set of models to predict the probability of an animal being probang positive given its antibody response in three common non-structural protein (NSP) ELISAs and its age. We argue that, in natural ecological settings, the current definition of a ”carrier” fails to capture the dynamics of either persistence of the virus (as measured by recovery using probangs) or the uncertainty in transmission from such animals that the term implies. In these respects it is not particularly useful. We therefore propose the first predictive statistical models for identifying persistently infected cattle in an endemic setting that captures some of the dynamics of the probability of persistence. Furthermore, we provide a set of predictive tools to use alongside NSP ELISAs to help target persistently infected cattle

    Aposematic signaling and seasonal variation in dorsal pelage in a venomous mammal

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    In mammals, colouration patterns are often related to concealment, intraspecific communication, including aposematic signals, and physiological adaptations. Slow lorises (Nycticebus spp.) are arboreal primates native to Southeast Asia that display stark colour contrast, are highly territorial, regularly enter torpor, and are notably one of only seven mammal taxa that possess venom. All slow loris species display a contrasting stripe that runs cranial-caudally along the median sagittal plane of the dorsum. We examine whether these dorsal markings facilitate background matching, seasonal adaptations, and intraspecific signaling. We analyzed 195 images of the dorsal region of 60 Javan slow loris individuals (Nycticebus javanicus) from Java, Indonesia. We extracted greyscale RGB values from dorsal pelage using ImageJ software and calculated contrast ratios between dorsal stripe and adjacent pelage in eight regions. We assessed through generalized linear mixed models if the contrast ratio varied with sex, age, and seasonality. We also examined whether higher contrast was related to more aggressive behavior or increased terrestrial movement. We found that the dorsal stripe of N. javanicus changed seasonally, being longer and more contrasting in the wet season, during which time lorises significantly increased their ground use. Stripes were most contrasting in younger individuals of dispersal age that were also the most aggressive during capture. The dorsal stripe became less contrasting as a loris aged. A longer stripe when ground use is more frequent can be related to disruptive colouration. A darker anterior region by younger lorises with less fighting experience may allow them to appear larger and fiercer. We provide evidence that the dorsum of a cryptic species can have multimodal signals related to concealment, intraspecific communication, and physiological adaptations

    From international to local: Promoting local volunteer tourism to guarantee the persistence of wildlife conservation projects in the post-COVID-19 era

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    Volunteer tourists, often foreigners, collect essential data in wildlife conservation projects worldwide. Due to the COVID-19 pandemic, international tourism activities reduced drastically, forcing many conservation projects to shut down. Using a nine-year (2013–2021) case study in Indonesia, we examine how local and foreign tourists construct the meaning of their volunteer experiences in the light of COVID-19. We aim to highlight the potential benefits of local volunteer tourism to face the travel limitations posed by COVID-19, and to show an example of how conservation projects can overcome the challenges of the current and potential future pandemics. We recruited 117 volunteers (49 Indonesians, 68 foreign; 73 females, 44 males; mean age: 24.2 ± SD 4.7) that collected 50.8% of the total amount of data collected by the project over the same period. Of the 117 volunteers, 81 of them (38 Indonesians, 43 foreigners) filled in a feedback form at the end of their stay. Via logistic regressions, we found that Indonesian volunteers declared more positive feedback on the logistics at the research station (p = 0.047). Via Bayesian structural equation models, we found that Indonesian volunteers reported significantly more frequently than foreign volunteers that they learned new skills (89% Credible Interval = 0.017–0.351) and that they gained personal wisdom, growth and maturity (89% Credible Interval = 0.891–1.003) from the volunteer experience. The volunteer program evolved from being 100% foreign volunteers in 2013 to 100% Indonesian volunteers by 2020 at the peak of the pandemic, which helped maintain the continuity of the research and conservation activities. We presented the positive implications of shifting towards local volunteer tourists in a long-term conservation project. We suggest that promoting local volunteer tourism through training new generations of nationals in conservation projects is key to guarantee the persistence of such initiatives in the post-COVID-19 Era

    Serological profile of foot-and-mouth disease in wildlife populations of West and Central Africa with special reference to Syncerus caffer subspecies

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    The role which West and Central African wildlife populations might play in the transmission dynamics of FMD is not known nor have studies been performed in order to assess the distribution and prevalence of FMD in wild animal species inhabiting those specific regions of Africa. This study reports the FMD serological profile extracted from samples (n = 696) collected from wildlife of West and Central Africa between 1999 and 2003. An overall prevalence of FMDV NSP reactive sera of 31.0% (216/696) was estimated, where a significant difference in seropositivity (p = 0.000) was reported for buffalo (64.8%) as opposed to other wild animal species tested (17.8%). Different levels of exposure to the FMDV resulted for each of the buffalo subspecies sampled (p = 0.031): 68.4%, 50.0% and 0% for Nile Buffalo, West African Buffalo and African Forest Buffalo, respectively. The characterisation of the FMDV serotypes tested for buffalo found presence of antibodies against all the six FMDV serotypes tested, although high estimates for type O and SAT 3 were reported for Central Africa. Different patterns of reaction to the six FMDV serotypes tested were recorded, from sera only positive for a single serotype to multiple reactivities. The results confirmed that FMDV circulates in wild ruminants populating both West and Central Africa rangelands and in particular in buffalo, also suggesting that multiple FMDV serotypes might be involved with type O, SAT 2 and SAT 1 being dominant. Differences in serotype and spill-over risk between wildlife and livestock likely reflect regional geography, historical circulation and differing trade and livestock systems

    South-South technology transfer of low-carbon innovation: large Chinese hydropower dams in Cambodia

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    Large dams have been controversially debated for decades due to their large‐scale and often irreversible social and environmental impacts. In the pursuit of low‐carbon energy and climate change mitigation, hydropower is experiencing a new renaissance. At the forefront of this renaissance are Chinese actors as the world's largest hydropower dam‐builders. This paper aims to discuss the role of South–South technology transfer of low‐carbon energy innovation and its opportunities and barriers by using a case study of the first large Chinese‐funded and Chinese‐built dam in Cambodia. Using the Kamchay Dam as an example, the paper finds that technology transfer can only be fully successful when host governments and organizations have the capacity to absorb new technologies. The paper also finds that technology transfer in the dam sector needs to go beyond hardware and focus more on the transfer of expertise, skills and knowledge to enable long‐term sustainable development
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