1,495 research outputs found
Two subpopulations of Crocosphaera watsonii have distinct distributions in the North and South Pacific
Get PDFCrocosphaera watsonii is a unicellular nitrogen (N2)-fixing cyanobacterium with ecological importance in oligotrophic oceans. In cultivated strains there are two phenotypes of C.?watsonii (large and small cells) with differences that could differentially impact biogeochemical processes. Recent work has shown the phenotypes diverged through loss or addition of type-specific genes in a fraction of their genomes, whereas the rest of the genomes were maintained at 99–100% DNA identity. Previous molecular assays for C.?watsonii abundances targeted the conserved regions and therefore could not differentiate between phenotypes, so their relative distributions in natural communities were unknown. To determine phenotype distributions, this study developed and applied type-specific quantitative polymerase chain reaction assays to samples from the North and South Pacific. Abundances of both Crocosphaera types declined sharply with depth between 45 and 75?m in both sites. In surface water small cells were 10–100 times more abundant than large cells in the N. Pacific, whereas in the S. Pacific the two phenotypes were nearly equal. Evidence for large cell aggregation was only found in N. Pacific samples. The differences in C.?watsonii sub-populations in the North and South Pacific have direct implications for biogeochemistry and carbon export in oligotrophic gyres
Metabolic versatility of the Riftia pachyptila endosymbiont revealed through metagenomics
No full textThe facultative symbiont of Riftia pachyptila, named here Candidatus Endoriftia persephone, has evaded culture to date, but much has been learned regarding this symbiosis over the past three decades since its discovery. The symbiont population metagenome was sequenced in order to gain insight into its physiology. The population genome indicates that the symbionts use a partial Calvin–Benson Cycle for carbon fixation and the reverse TCA cycle (an alternative pathway for carbon fixation) that contains an unusual ATP citrate lyase. The presence of all genes necessary for heterotrophic metabolism, a phosphotransferase system, and dicarboxylate and ABC transporters indicate that the symbiont can live mixotrophically. The metagenome has a large suite of signal transduction, defence (both biological and environmental) and chemotaxis mechanisms. The physiology of Candidatus Endoriftia persephone is explored with respect to functionality while associated with a eukaryotic host, versus free-living in the hydrothermal environment
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Comparative genomics and natural distributions of phenotypically distinct strains of the nitrogen-fixing cyanobacterium Crocosphaera watsonii
Get PDFCrocosphaera watsonii is an ecologically important marine unicellular diazotrophic cyanobacterium. It is often abundant in oligotrophic ocean regions where it provides fixed nitrogen to nutrient-limited phytoplankton communities. Previous genetic studies have observed genetic rearrangements but very little sequence variation among natural populations or cultivated strains of Crocosphaera. Those strains exhibit two phenotypes (large- and small-cell) with characteristics that suggest different ecological roles and niches. Prior to this work, the genetic basis for the phenotypic differences was unknown, and molecular methods for enumerating natural C. watsonii could not differentiate between phenotypes. To address those unanswered scientific questions, these studies compared the genomes of six C. watsonii strains, three of each phenotype, which were isolated over large spatial and temporal distances. A large portion of those genome sequences were shared among all strains with nearly 100% nucleotide identity. However, there were also genes that were specific to each strain, and others were specific to each phenotype, including some which could explain phenotypic differences (e.g. EPS biosynthesis). Relative to small-cell strains, large-cell strains had larger genomes and additional genetic capabilities, including possibly increased adaptations to iron and phosphorus limitation. Clustering based on genome sequences and content showed that strains with a common phenotype were evolutionarily most closely related, regardless of their time and location of isolation. Surprisingly, the genome of the C. watsonii type-strain, WH8501, was quite unusual, even compared to those with the same phenotype, suggesting it may not be appropriately representative of the species. To investigate distributions of Crocosphaera types in the marine environment, molecular assays were developed, based on phenotype-specific genes, and applied to samples from the North and South Pacific. In those samples, small-cells dominated in the upper 75 m where abundance of both types was much greater, while large-cells dominated in samples with lower counts between 100 m and 175 m. There was also more evidence that large-cells form aggregates in the N. Pacific. Future studies will be important to determine which of the initial C. watsonii patterns described here can be generalized, both in genomes, and in natural distributions of the two types
De Bank The Bench
No full textThis book and the accompanying exhibition are the result of a Form Studies exercise held at the Faculty of Architecture at Delft University of Technology (TU Dellt). This practical exercise, entitled 'The Beneh', is part of a second year teaching "Block" (coordinated by Max Risselada) with 'Imaging and Materialisation' as its central theme. The block lasts eight weeks and is part of the basic educational programme at the faculty. It focuses on aspects of industrial (pre)labrication, montage and detailing. The practical study is carried out parallel with the other items of the block, which concentrate on the design of lightweight dwellings and the analysis of design precedents. 'The Bench' was developed and offered by the staff of the Form Studies group, which is part of the Media section. Major themes in the Media programme are Design Visualisation and Presentation. The Form Studies curriculum focuses on aspects of Formal and Spatial Composition. In addition, Form Studies is responsible for the teaching ol three dimensional Modelmaking techniques, which takes place in a well-equipped workshop. In this particular exercise the aspects ol Composition and Modelling come together. As in the previous application, 'The Tabie, as a metaphor lor architecture' , the task that was set was limited and (seemingly) simple: design a bench for the public realm and then 'build' the design in the form of a scale model 1 : 5 or 1 : 10. The students were stimulated to deal with the bench as an architectural object. The ambition of this approach is to confront students with design themes such as function, shape and proportion, but also with qualities and combinations ol materials, logical and expressive detailing and the consequences of 'making'. The idea is that students should continue refining their designs in the realisation phase. For many students, this is an experience approaching that of a first 'realised' project (though of course limited in scope and scale). The exercise, with 'The Bench' as its theme, was offered during 1994 and 1995. The students worked with considerable enthusiasm and the results were varied and, for second-year students, often surprisingly professional. For the Form Studies team this was a reason to organise an exhibition and this publication. We hope you will enjoy the results of the Bench project.ArchitectureArchitectur
Reply to Bench (1973)
No full textThe author is in agreement with Bench 1973 that without specific analysis one cannot be certain that the auditory output from a given loudspeaker matches the input to that speaker. However, issue is taken with Bench concerning the results obtained by Ashton 1971
Designing a landscape bench
No full textThe built landscape that ranges from the paved concrete paths that we walk on to the towering buildings that can rise thousands of feet above. These objects were intentionally designed by people to serve specific functions to benefit us. However, as time moves forward, and we as people change, our designs can become outdated, no longer relevant, or simply not exciting. The landscape bench is one part of the landscape that has struggled to evolve over the years and is limited in the number of functions that it could provide. The landscape bench has been documented for hundreds of years and has served as a place of refuge in the landscape - providing a hub for social interaction, a location to go to, and simply a place to sit. Our current perception and expectations have limited this piece of the landscape to just a place to sit, not allowing for even simple changes to its simple design. Through the design and build process this thesis investigates topics regarding material sustainability, site specific designs, and social interactions in relation to bench design and construction. Through the creation of a prototype and a final model this project created a well researched and designed bench for its site. The process demonstrated that making considerations for history, sustainability and case studies, the landscape bench can be designed and built with meaning and purpose.M.L.A.Includes bibliographical reference
Gene expression patterns in Euglena gracilis: Insights into the cellular response to environmental stress
Get PDFTo better understand Euglena gracilis gene expression under different stress conditions (Chromium, Streptomycin or darkness), we undertook a survey of the E. gracilis transcriptome by cDNA sequencing and microarray analysis. First, we constructed a non-normalized cDNA library from the E. gracilis UTEX strain and sequenced a total of 1000 cDNAs. Six hundred and ten of these ESTs were similar to either Plantae or Protistae genes (e-value < e- 10). Second, microarrays were built by spotting all the ESTs onto mirror slides. Microarray expression analysis indicated that 90 out of those 610 ESTs changed their expression level in response to different stress treatments (p < 0.05). In addition, we detected 10 ESTs that changed expression levels irrespective of the tested stress. These may be considered as part of a larger set of stress-related genes in E. gracilis. Finally, we identified 23 unknown ESTs (U-ESTs) following the expression profiles of these putative stress-related genes suggesting that they could be related to the cellular mechanism of stress response.Fil: Dos Santos Ferreira, Veronica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires; ArgentinaFil: Rocchetta, Iara. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Conforti, Visitacion Teresa D.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Bench, Shellie. University of California; Estados UnidosFil: Feldman, Robert. University of California; Estados Unidos. SymBio Corporation; Estados UnidosFil: Levin, Mariano Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires; Argentina. lnstitut Cochin; Franci
Bench-scale centrifuge testing to determine the hydraulic conductivity of clayey soils
No full textThe purpose of this research is to validate a mathematical model for flow through saturated and unsaturated porous media using a bench-scale centrifuge for an accurate determination of the hydraulic conductivity (function of the saturation degree of a soil) within a limited time at a reasonable price. The aim of this paper is to show preliminary results of this investigation where the validation and calibration of the mathematical model is performed determining the hydraulic conductivity of saturated porous media, such as kaolin clay and glass porous filters, with a bench-scale centrifuge
Utilization of a dumbbell floor press in predicting an estimated 1RM max barbell bench bress using repetitions to fatigue
No full textThis research aims to investigate the relationship between the performance of a dumbbell floor press and the traditional barbell bench press, as a safer alternative means of assessing maximal strength in upper body pressing. The 1 repetition maximum (1RM) test using a Barbell Bench Press (BBP) has been widely used for this purpose but can be time-consuming and poses an increased risk of injury when performed incorrectly, particularly among novice individuals. The most common injuries associated with the bench press are anterior glenohumeral instability, atraumatic osteolysis of the distal clavicle, and pectoralis major rupture. Alternative protocols for estimating 1RM, such as the YMCA bench press, sub-maximal BBP, and push-ups, have been established but also pose some risk of injury. The theory is that performing a dumbbell floor press may be a safer alternative, as it provides a stable base for the scapula and shortens the range of motion on the press, eliminating excessive anterior humeral slide. Two case studies have shown that exercises using a bench in horizontal and push-ups can cause bilateral shoulder dislocation. This study aims to fill the gap in the literature by examining the relationship between the dumbbell floor press and the barbell bench press. The findings of this study may provide health professionals with an alternative means of assessing upper body pressing strength for participants who may be at risk of injury with traditional testing protocols.
Poster submission was sponsored by Dr.Ken Anderson, (Sports Science Department) for course SPSC 4256 and was presented at the New Westminster campus on April 12, 2023, for Student Research Days 2023.Not peer reviewe
GSL-Bench: High Fidelity Gas Source Localization Benchmarking
No full textGas Source Localization (GSL) is a challenging field of research within the robotics community. Existing methods vary widely and each has its own strengths and weaknesses. Existing GSL evaluations vary in environment size, wind conditions, and gas simulation fidelity, thereby complicating objective comparison between algorithms. They also lack photo-realistic rendering for the integration of obstacle avoidance. In this paper, we propose GSL-Bench, a benchmarking suite to evaluate the performance of GSL algorithms. GSL-Bench features high-fidelity graphics and gas simulation. Realism is further increased by simulating relevant gas and wind sensors. Scene generation is simplified with the introduction of AutoGDM+, capable of procedural environment generation, CFD and particle-based gas dispersion simulation. To illustrate GSL-Bench's capabilities, three algorithms are compared in six warehouse settings of increasing complexity: E. Coli, dung beetle and a random walker. Our results demonstrate GSL-Bench's ability to provide valuable insights into algorithm performance.https://sites.google.com/view/gslbench/ Website providing additional results and instructionsAerospace Engineerin
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