247 research outputs found
An HDG Method for Dirichlet Boundary Control of Convection Dominated Diffusion PDE
We first propose a hybridizable discontinuous Galerkin (HDG) method to
approximate the solution of a \emph{convection dominated} Dirichlet boundary
control problem. Dirichlet boundary control problems and convection dominated
problems are each very challenging numerically due to solutions with low
regularity and sharp layers, respectively. Although there are some numerical
analysis works in the literature on \emph{diffusion dominated} convection
diffusion Dirichlet boundary control problems, we are not aware of any existing
numerical analysis works for convection dominated boundary control problems.
Moreover, the existing numerical analysis techniques for convection dominated
PDEs are not directly applicable for the Dirichlet boundary control problem
because of the low regularity solutions. In this work, we obtain an optimal a
priori error estimate for the control under some conditions on the domain and
the desired state. We also present some numerical experiments to illustrate the
performance of the HDG method for convection dominated Dirichlet boundary
control problems
Dredging fundamentally reshapes the ecological significance of 3D terrain features for fish in estuarine seascapes
Context: Landscape modification alters the condition of ecosystems and the structure of terrain, with widespread impacts on biodiversity and ecosystem functioning. Seafloor dredging impacts a diversity of flora and fauna in many coastal landscapes, and these processes also transform three-dimensional terrain features. The potential ecological significance of these terrain changes in urban seascapes has, however, not been investigated.
Objectives: We examined the effects of terrain variation on fish assemblages in 29 estuaries in eastern Australia, and tested whether dredging changes how fish associate with terrain features.
Methods: We surveyed fish assemblages with baited remote underwater video stations and quantified terrain variation with nine complementary metrics (e.g. depth, aspect, curvature, slope, roughness), extracted from bathymetry maps created with multi-beam sonar.
Results: Fish diversity and abundance were strongly linked to seafloor terrain in both natural and dredged estuaries, and were highest in shallow waters and near features with high curvature. Dredging, however, significantly altered the terrain of dredged estuaries and transformed the significance of terrain features for fish assemblages. Abundance and diversity switched from being correlated with lower roughness and steeper slopes in natural estuaries to being linked to features with higher roughness and gentler slopes in dredged estuaries.
Conclusions: Contrasting fish-terrain relationships highlight previously unrecognised ecological impacts of dredging, but indicate that plasticity in terrain use might be characteristic of assemblages in urban landscapes. Incorporating terrain features into spatial conservation planning might help to improve management outcomes, but we suggest that different approaches would be needed in natural and modified landscapes
Seafloor Terrain Shapes the Three-dimensional Nursery Value of Mangrove and Seagrass Habitats
Mangroves and seagrasses are important nurseries for many marine species, and this function is linked to the complexity and context of these habitats in coastal seascapes. It is also connected to bathymetric features that influence habitat availability, and the accessibility of refuge habitats, but the significance of terrain variation for nursery function is unknown. To test whether seafloor terrain influences nursery function, we surveyed fish assemblages from mangrove and seagrass habitats in 29 estuaries in eastern Australia with unbaited underwater cameras and quantified the surrounding three-dimensional terrain with a set of complementary surface metrics (that is, depth, aspect, curvature, slope, roughness) applied to sonar-derived bathymetric maps. Terrain metrics explained variability in assemblages in both mangroves and seagrasses, with differing effects for the entire fish assemblage and nursery species composition, and between habitats. Higher depth, plan curvature (concavity or convexity) and roughness (backscatter) were negatively correlated with abundance and diversity in mangroves and positively linked to abundance and diversity in seagrass. Mangrove nursery species (6 species) were most abundant in forests adjacent to flats with concave holes, rough substrates and low-moderate depths, whereas seagrass nursery species (3 species) were most abundant in meadows adjacent to deep channels with soft mounds and ledges. These findings indicate that seafloor terrain influences nursery function and demonstrate contrasting effects of terrain variation in mangroves and seagrass. We suggest that incorporating three-dimensional terrain into coastal conservation and restoration plans could help to improve outcomes for fisheries management, but contrasting strategies might be needed for different nursery habitats
Turning a lost reef ecosystem into a national restoration program
Achieving a sustainable socioecological future now requires large-scale environmental repair across legislative borders. Yet, enabling large-scale conservation is complicated by policy-making processes that are disconnected from socioeconomic interests, multiple sources of knowledge, and differing applications of policy. We considered how a multidisciplinary approach to marine habitat restoration generated the scientific evidence base, community support, and funding needed to begin the restoration of a forgotten, functionally extinct shellfish reef ecosystem. The key actors came together as a multidisciplinary community of researchers, conservation practitioners, recreational fisher communities, and government bodies that collaborated across sectors to rediscover Australia's lost shellfish reefs and communicate the value of its restoration. Actions undertaken to build a case for large-scale marine restoration included synthesizing current knowledge on Australian shellfish reefs and their historical decline, using this history to tell a compelling story to spark public and political interest, integrating restoration into government policy, and rallying local support through community engagement. Clearly articulating the social, economic, and environmental business case for restoration led to state and national funding for reef restoration to meet diverse sustainability goals (e.g., enhanced biodiversity and fisheries productivity) and socioeconomic goals (e.g., job creation and recreational opportunities). A key lesson learned was the importance of aligning project goals with public and industry interests so that projects could address multiple political obligations. This process culminated in Australia's largest marine restoration initiative and shows that solutions for large-scale ecosystem repair can rapidly occur when socially valued science acts on political opportunities
The lipids of the common house cricket,Acheta domesticus L. I. Lipid classes and fatty acid distribution
The lipids of the common house cricket,Acheta domesticus L., have been examined with the following results. The fatty acids associated with the lipid extracts do not change significantly from the third through the eleventh week of the cricketsâ postembryonic life. The major fatty acids are linoleic (30â40%), oleic (23â27%), palmitic (24â30%), and stearic acids (7â11%). There are smaller amounts of palmitoleic (3â4%), myristic (âŒ1%), and linolenic acids (<1%). The fatty acid composition of the cricket lipids reflects but is not identical to the fatty acids of the dietary lipids: linoleic (53%), oleic (24%), palmitic (15%), stearic (3%), myristic (2%), and linolenic acid (2%).The amount of triglycerides present in the crickets increases steadily from the second through the seventh or eighth week of postembryonic life, then drops sharply. Other lipid classes, such as hydrocarbons, simple esters, diglycerides, monoglycerides, sterols, and free fatty acids remain about constant. The composition of the fatty acids associated with the triâ, diâ, and monoglycerides and the free fatty acid fraction are all about the same. The fatty acids associated with the simple esters are high in stearic acid.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142007/1/lipd0247.pd
Ten Years After: An âAusterity Auditâ of Services and Living Conditions for People Living with HIV in the UK, a Decade after the Financial Crisis
Cite as: HIV Psychosocial Network (2018). Ten Years After: An âAusterity Auditâ of Services and Living Conditions for People Living with HIV in the UK, a Decade after the Financial Crisis
The politics of aspiration: neo-liberal education policy, 'low' parental aspirations, and primary school Extended Services in disadvantaged communities
Geographical research on education has grown rapidly in both volume and scope during the
first decade of the twenty-first century, and one relatively new theme to emerge from this
growing literature is that of education and aspiration. Much of the nascent interest in
aspiration concerns access to quality schooling and University education. In this paper by
contrast we highlight the importance of studying the ways aspirations are (re)produced within
the school community. Our empirical focus is on low-income England under New Labour.
Here we pursue a two-fold approach: firstly examining how education professionals define
parental aspirations for primary-aged children as low; before secondly considering their
alternative understandings of appropriate aspirations and the practices through which they
seek to promote these, both in school and through the use of Extended Services for parents
and children. In conclusion we highlight the importance of inward and outward geographies
of education which ârecoupleâ schools with their social context, and discuss the moral and political ambiguities involved in practices designed to raise aspirations
Gene expression and splicing alterations analyzed by high throughput RNA sequencing of chronic lymphocytic leukemia specimens.
BackgroundTo determine differentially expressed and spliced RNA transcripts in chronic lymphocytic leukemia specimens a high throughput RNA-sequencing (HTS RNA-seq) analysis was performed.MethodsTen CLL specimens and five normal peripheral blood CD19+ B cells were analyzed by HTS RNA-seq. The library preparation was performed with Illumina TrueSeq RNA kit and analyzed by Illumina HiSeq 2000 sequencing system.ResultsAn average of 48.5 million reads for B cells, and 50.6 million reads for CLL specimens were obtained with 10396 and 10448 assembled transcripts for normal B cells and primary CLL specimens respectively. With the Cuffdiff analysis, 2091 differentially expressed genes (DEG) between B cells and CLL specimens based on FPKM (fragments per kilobase of transcript per million reads and false discovery rate, FDR qâ<â0.05, fold change >2) were identified. Expression of selected DEGs (nâ=â32) with up regulated and down regulated expression in CLL from RNA-seq data were also analyzed by qRT-PCR in a test cohort of CLL specimens. Even though there was a variation in fold expression of DEG genes between RNA-seq and qRT-PCR; more than 90 % of analyzed genes were validated by qRT-PCR analysis. Analysis of RNA-seq data for splicing alterations in CLL and B cells was performed by Multivariate Analysis of Transcript Splicing (MATS analysis). Skipped exon was the most frequent splicing alteration in CLL specimens with 128 significant events (P-value <0.05, minimum inclusion level difference >0.1).ConclusionThe RNA-seq analysis of CLL specimens identifies novel DEG and alternatively spliced genes that are potential prognostic markers and therapeutic targets. High level of validation by qRT-PCR for a number of DEG genes supports the accuracy of this analysis. Global comparison of transcriptomes of B cells, IGVH non-mutated CLL (U-CLL) and mutated CLL specimens (M-CLL) with multidimensional scaling analysis was able to segregate CLL and B cell transcriptomes but the M-CLL and U-CLL transcriptomes were indistinguishable. The analysis of HTS RNA-seq data to identify alternative splicing events and other genetic abnormalities specific to CLL is an added advantage of RNA-seq that is not feasible with other genome wide analysis
Annual cycles are the most common reproductive strategy in African tropical tree communities
Abstract We present the first crossâcontinental comparison of the flowering and fruiting phenology of tropical forests across Africa. Flowering events of 5446 trees from 196 species across 12 sites and fruiting events of 4595 trees from 191 species across 11 sites were monitored over periods of 6 to 29Â years and analyzed to describe phenology at the continental level. To study phenology, we used Fourier analysis to identify the dominant cycles of flowering and fruiting for each individual tree and we identified the time of year African trees bloom and bear fruit and their relationship to local seasonality. Reproductive strategies were diverse, and no single regular cycle was found in >50% of individuals across all 12 sites. Additionally, we found annual flowering and fruiting cycles to be the most common. Subâannual cycles were the next most common for flowering, whereas supraâannual patterns were the next most common for fruiting. We also identify variation in different subsets of species, with species exhibiting mainly annual cycles most common in West and West Central African tropical forests, while more species at sites in East Central and East African forests showed cycles ranging from subâannual to supraâannual. Despite many trees showing strong seasonality, at most sites some flowering and fruiting occurred all year round. Environmental factors with annual cycles are likely to be important drivers of seasonal periodicity in trees across Africa, but proximate triggers are unlikely to be constant across the continent.Additional co-authors: Roman M. Wittig, Thomas Breuer, Mireille BreuerâNdoundou Hockemba, Crickette M. Sanz, David B. Morgan, Anne E. Pusey, Badru Mugerwa, Baraka Gilagiza, Caroline Tutin, Corneille E. N. Ewango, Douglas Sheil, Edmond Dimoto, FidĂšle Baya, Flort Bujo, Fredrick Ssali, JeanâThoussaint Dikangadissi, Kim Valenta, Michel Masozera, Michael L. Wilson, Robert Bitariho, Sydney T. Ndolo Ebika, Sylvie GourletâFleury, Felix Mulindahabi, Colin M. Beal
Geographic Variation in Salt Marsh Structure and Function for Nekton: a Guide to Finding Commonality Across Multiple Scales
Coastal salt marshes are distributed widely across the globe and are considered essential habitat for many fish and crustacean species. Yet, the literature on fishery support by salt marshes has largely been based on a few geographically distinct model systems, and as a result, inadequately captures the hierarchical nature of salt marsh pattern, process, and variation across space and time. A better understanding of geographic variation and drivers of commonalities and differences across salt marsh systems is essential to informing future management practices. Here, we address the key drivers of geographic variation in salt marshes: hydroperiod, seascape configuration, geomorphology, climatic region, sediment supply and riverine input, salinity, vegetation composition, and human activities. Future efforts to manage, conserve, and restore these habitats will require consideration of how environmental drivers within marshes affect the overall structure and subsequent function for fisheries species. We propose a future research agenda that provides both the consistent collection and reporting of sources of variation in small-scale studies and collaborative networks running parallel studies across large scales and geographically distinct locations to provide analogous information for data poor locations. These comparisons are needed to identify and prioritize restoration or conservation efforts, identify sources of variation among regions, and best manage fisheries and food resources across the globe
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