1,157 research outputs found
Direct effects of warming increase woody plant abundance in a subarctic wetland
Both the direct effects of warming on a species’ vital rates and indirect effects of warming caused by interactions with neighboring species can influence plant populations. Furthermore, herbivory mediates the effects of warming on plant community composition in many systems. Thus, determining the importance of direct and indirect effects of warming, while considering the role of herbivory, can help predict long-term plant community dynamics. We conducted a field experiment in the coastal wetlands of western Alaska to investigate how warming and herbivory influence the interactions and abundances of two common plant species, a sedge, Carex ramenskii, and a dwarf shrub, Salix ovalifolia. We used results from the experiment to model the equilibrium abundances of the species under different warming and grazing scenarios and to determine the contribution of direct and indirect effects to predict population changes. Consistent with the current composition of the landscape, model predictions suggest that Carex is more abundant than Salix under ambient temperatures with grazing (53% and 27% cover, respectively). However, with warming and grazing, Salix becomes more abundant than Carex (57% and 41% cover, respectively), reflecting both a negative response of Carexand a positive response of Salix to warming. While grazing reduced the cover of both species, herbivory did not prevent a shift in dominance from sedges to the dwarf shrub. Direct effects of climate change explained about 97% of the total predicted change in species cover, whereas indirect effects explained only 3% of the predicted change. Thus, indirect effects, mediated by interactions between Carex and Salix, were negligible, likely due to use of different niches and weak interspecific interactions. Results suggest that a 2°C increase could cause a shift in dominance from sedges to woody plants on the coast of western Alaska over decadal timescales, and this shift was largely a result of the direct effects of warming. Models predict this shift with or without goose herbivory. Our results are consistent with other studies showing an increase in woody plant abundance in the Arctic and suggest that shifts in plant–plant interactions are not driving this change
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Do Transmission Mechanisms or Social Systems Drive Cultural Dynamics in Socially Structured Populations?
Cultural traits spread via multiple mechanisms among individuals within social groups, including via transmission biases that occur when subordinates copy from dominants (prestige transmission), or via common cultural trait variants that are favoured over rare ones (consensus transmission). Most animal populations are subdivided into social groups where cultural learning occurs, yet theoretical studies of cultural trait transmission have tended to focus on within-group transmission dynamics. We developed an agent-based model of cultural transmission in socially structured populations in which a trait arises in one individual and either persists until a stable population equilibrium is reached, or goes extinct. With this model, we systematically varied group size, rates of dispersal among groups, mortality rates, transmission characteristics, the benefit of the cultural trait (including possibly negative benefits), and whether individuals disperse locally or randomly. We used generalized linear models to examine how changes in these parameters influence trait extinction, equilibrium prevalence and time to equilibrium. Four traits increased the probability of extinction: smaller group size, higher background mortality, lower transmission rate and more costly traits (although costly traits sometimes reached an equilibrium). Local dispersal and biased transmission mechanisms (prestige and consensus) had no significant effects on extinction probability, and similar patterns were found for equilibrium prevalence. We found that a lower dispersal rate and local dispersal slowed the time required for a trait to reach equilibrium, as did smaller groups, lower transmission rates and lower costs. Collectively, these analyses reveal that prestige and consensus transmission have weaker effects than other factors associated with demographic and social conditions.Human Evolutionary Biolog
Psychometric Assessment of the Comprehensive Effects of Alcohol Questionnaire: Comparing a Brief Version to the Original Full Scale
The current set of studies compared the psychometric properties of the original Comprehensive Effects of Alcohol Questionnaire (CEOA) to a 15-item version (B-CEOA) in a nonclinical undergraduate sample (N = 581), and attempted to replicate and extend the B-CEOA findings in an undergraduate sample referred to an alcohol intervention (N = 734). Psychometric assessment included construct validity, internal consistency, and concurrent validity, using both “positive” and “negative” expectancy items in all analyses. Results provided further support for the empirical validity of the original CEOA, and provided support for the use of the B-CEOA despite the reduction in the number of items. The B-CEOA factor structures obtained using exploratory and confirmatory techniques provided support for a 4-factor structure of expectancies and 3-factor structure of valuations. Findings reveal potential problems with “positive” and “negative” expectancy items. Trade-offs regarding factor structure, internal consistency, and administration time should be considered in using the B-CEOA vs. the CEOA
Influence of vertical flows in wells on groundwater sampling
Pumped groundwater sampling evaluations often assume that horizontal head gradients predominate and the sample comprises an average of water quality variation over the well screen interval weighted towards contributing zones of higher hydraulic conductivity (a permeability-weighted sample). However, the pumping rate used during sampling may not always be sufficient to overcome vertical flows in wells driven by ambient vertical head gradients. Such flows are reported in wells with screens between 3 and 10 m in length where lower pumping rates are more likely to be used during sampling. Here, numerical flow and particle transport modeling is used to provide insight into the origin of samples under ambient vertical head gradients and under a range of pumping rates. When vertical gradients are present, sample provenance is sensitive to pump intake position, pumping rate and pumping duration. The sample may not be drawn from the whole screen interval even with extended pumping times. Sample bias is present even when the ambient vertical flow in the wellbore is less than the pumping rate. Knowledge of the maximum ambient vertical flow in the well does, however, allow estimation of the pumping rate that will yield a permeability-weighted sample. This rate may be much greater than that recommended for low-flow sampling. In practice at monitored sites, the sampling bias introduced by ambient vertical flows in wells may often be unrecognized or underestimated when drawing conclusions from sampling results. It follows that care should be taken in the interpretation of sampling data if supporting flow investigations have not been undertaken
Associations between Cognition, Gender and Monocyte Activation among HIV Infected Individuals in Nigeria.
The potential role of gender in the occurrence of HIV-related neurocognitive impairment (NCI) and associations with markers of HIV-related immune activity has not been previously examined. In this study 149 antiretroviral-naïve seropositive subjects in Nigeria (SP, 92 women and 57 men) and 58 seronegative (SN, 38 women and 20 men) were administered neuropsychological testing that assessed 7 ability domains. From the neuropsychological test scores was calculated a global deficit score (GDS), a measure of overall NCI. Percentages of circulating monocytes and plasma HIV RNA, soluble CD163 and soluble CD14 levels were also assessed. HIV SP women were found to be younger, more educated and had higher CD4+ T cell counts and borderline higher viral load measures than SP men. On the neuropsychological testing, SP women were more impaired in speed of information processing and verbal fluency and had a higher mean GDS than SN women. Compared to SP men, SP women were also more impaired in speed of information processing and verbal fluency as well as on tests of learning and memory. Numbers of circulating monocytes and plasma sCD14 and sCD163 levels were significantly higher for all SP versus all SN individuals and were also higher for SP women and for SP men versus their SN counterparts. Among SP women, soluble CD14 levels were slightly higher than for SP men, and SP women had higher viral load measurements and were more likely to have detectable virus than SP men. Higher sCD14 levels among SP women correlated with more severe global impairment, and higher viral load measurements correlated with higher monocyte numbers and sCD14 and sCD14 levels, associations that were not observed for SP men. These studies suggest that the risk of developing NCI differ for HIV infected women and men in Nigeria and, for women, may be linked to effects from higher plasma levels of HIV driving activation of circulating monocytes
Prioritization of Managed Pork Supply Movements during a FMD Outbreak in the US
In the event of a Foot and Mouth Disease (FMD) outbreak in the U.S., local, state, and federal authorities will implement a foreign animal disease emergency response plan restricting the pork supply chain movements and likely disrupting the continuity of the swine industry business. To minimize disruptions of the food supply while providing an effective response in an outbreak, it is necessary to have proactive measures in place to ensure minimal disease spread and maximum continuation of business. Therefore, it is critical to identify candidate movements for proactive risk assessments: those that are both most likely to contribute to disease spread and most necessary for business continuity. To do this, experts from production, harvest, retail, and allied pork industries assessed 30 common pork supply movements for risk of disease spread and industry criticality. The highest priority movements for conducting a risk assessment included the movement of weaned pigs originating from multiple sow farm sources to an offsite nursery or wean to finish facility, the movement of employees or commercial crews, the movement of vaccination crews, the movement of dedicated livestock hauling trucks, and the movement of commercial crews such as manure haulers and feed trucks onto, off, or between sites. These critical movements, along with several others identified in this study, will provide an initial guide for prioritization of risk management efforts and resources to be better prepared in the event of a FMD outbreak in the United States. By specifically and proactively targeting movements that experts agree are likely to spread the disease and are critical to the continuity of business operations, potentially catastrophic consequences in the event of an outbreak can be limited
LAPORAN INDIVIDU KEGIATAN PENGALAMAN LAPANGAN (PPL) PERIODE 18 JULI s.d 15 SEPTEMBER 2016 SMA NEGERI 2 BANGUNTAPAN
Praktik Pengalaman Lapangan (PPL) merupakan suatu wadah
untuk menerapkan/mengaplikasikan ilmu yang selama ini telah dipelajari
dalam bidang keahlian maupun ilmu keguruan yang berkaitan dengan
peserta didik dalam proses belajar mengajar. Praktik pengalaman lapangan
atau praktik mengajar ini mulai dilaksanakan pada tanggal 18 Juli s.d. 15
September 2016 berlokasi di SMA N 2 Banguntapan. Dalam praktik
mengajar mahasiswa terlebih dahulu melaksanakan persiapan
pembelajaran, yaitu membuat perencanaan pembelajaran dimulai dengan
membuat rencana pelaksanaan pembelajaran sampai dengan evaluasi yang
dilaksanakan. Kemudian melakukan koordinasi dan konsultasi kepada
guru pembimbing di sekolah tersebut.
Dalam bimbingan PPL, mahasiswa (penulis) mendapatkan
kesempatan untuk melaksanakan pembelajaran di kelas X IPS 1 dan X IPS
2. Kurikulum yang digunakan adalah Kurikulum 2013 (K13). Begitu pula
dengan penulisan Rencana Pelaksanaan Pembelajarannya (RPP),
penggunaan metode pembelajaran yang diterapkan adalah dengan metode
Problem Based Learning dan Cooperative Learning. Sedangkan media
yang digunakan adalah White Board, LCD, spidol, lembar kerja dan
mengadakan tugas individu untuk mengetahui sejauh mana kemampuan
siswa dalam memahami materi yang telah disampaikan. Pada tahap
pelaksanaan, mahasiswa mengajar sebanyak 6 kali dengan alokasi masingmasing
3 jam pelajaran setiap pertemuan.
Program kegiatan PPL dapat terlaksana dengan baik dan lancar
berkat adanya bimbingan dan arahan dari guru pembimbing dan dosen
pembimbing selama praktik mengajar serta peran aktif peserta didik
selama berlangsungnya KBM. Selain itu terlaksananya program PPL ini
tidak terlepas dari dukungan dan bantuan dari pihak sekolah yang telah
memberikan keluasan kesempatan kepada para mahasiswa PPL untuk
mengembangkan potensi yang dimilikinya
Joint analysis of stressors and ecosystem services to enhance restoration effectiveness
With increasing pressure placed on natural systems by growing human populations, both scientists and resource managers need a better understanding of the relationships between cumulative stress from human activities and valued ecosystem services. Societies often seek to mitigate threats to these services through large-scale, costly restoration projects, such as the over one billion dollar Great Lakes Restoration Initiative currently underway. To help inform these efforts, we merged high-resolution spatial analyses of environmental stressors with mapping of ecosystem services for all five Great Lakes. Cumulative ecosystem stress is highest in near-shore habitats, but also extends offshore in Lakes Erie, Ontario, and Michigan. Variation in cumulative stress is driven largely by spatial concordance among multiple stressors, indicating the importance of considering all stressors when planning restoration activities. In addition, highly stressed areas reflect numerous different combinations of stressors rather than a single suite of problems, suggesting that a detailed understanding of the stressors needing alleviation could improve restoration planning. We also find that many important areas for fisheries and recreation are subject to high stress, indicating that ecosystem degradation could be threatening key services. Current restoration efforts have targeted high-stress sites almost exclusively, but generally without knowledge of the full range of stressors affecting these locations or differences among sites in service provisioning. Our results demonstrate that joint spatial analysis of stressors and ecosystem services can provide a critical foundation for maximizing social and ecological benefits from restoration investments. www.pnas.org/lookup/suppl/doi:10.1073/pnas.1213841110/-/DCSupplementa
Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks : results from an atmosphere-ocean general circulation model
© 2009 The Authors. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Biogeosciences 6 (2009): 2099-2120, doi:10.5194/bg-6-2099-2009Inclusion of fundamental ecological interactions between carbon and nitrogen cycles in the land component of an atmosphere-ocean general circulation model (AOGCM) leads to decreased carbon uptake associated with CO2 fertilization, and increased carbon uptake associated with warming of the climate system. The balance of these two opposing effects is to reduce the fraction of anthropogenic CO2 predicted to be sequestered in land ecosystems. The primary mechanism responsible for increased land carbon storage under radiatively forced climate change is shown to be fertilization of plant growth by increased mineralization of nitrogen directly associated with increased decomposition of soil organic matter under a warming climate, which in this particular model results in a negative gain for the climate-carbon feedback. Estimates for the land and ocean sink fractions of recent anthropogenic emissions are individually within the range of observational estimates, but the combined land plus ocean sink fractions produce an airborne fraction which is too high compared to observations. This bias is likely due in part to an underestimation of the ocean sink fraction. Our results show a significant growth in the airborne fraction of anthropogenic CO2 emissions over the coming century, attributable in part to a steady decline in the ocean sink fraction. Comparison to experimental studies on the fate of radio-labeled nitrogen tracers in temperate forests indicates that the model representation of competition between plants and microbes for new mineral nitrogen resources is reasonable. Our results suggest a weaker dependence of net land carbon flux on soil moisture changes in tropical regions, and a stronger positive growth response to warming in those regions, than predicted by a similar AOGCM implemented without land carbon-nitrogen interactions. We expect that the between-model uncertainty in predictions of future atmospheric CO2 concentration and associated anthropogenic climate change will be reduced as additional climate models introduce carbon-nitrogen cycle interactions in their land components.This work was supported
in part by NASA Earth Science Enterprise, Terrestrial Ecology
Program, grant #W19,953 to P. E. Thornton. Support was provided
by the National Center for Atmospheric Research (NCAR) through
the NCAR Community Climate System Modeling program,
and through the NCAR Biogeosciences program. Additional
support was provided by the US Department of Energy, Office
of Science, Office of Biological and Environmental Research.
I. Fung, S. Doney, N. Mahowald, and J. Randerson acknowledge
support from National Science Foundation, Atmospheric Sciences
Division, through the Carbon and Water Initiative
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