476 research outputs found

    Influence of osmotic and metal stresses on nitrogenase activity of cyanobacteria ýsolated from paddy fields

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    Samples were collected from paddy fields in Corum-Turk.ye. Nitrogen-free BG-11 medium was used for isolation of nitrogen fixing cyanobacteria. Acetylene reduction technique was used to determine the effects of different chemical agents on the nitrogenase activities of the cyanobacteria, which were identified at the genus level. Nostoc showed the highest nitrogenase activity (0.09 ethylene ƒÊl/mg.h) at 50 mM salt concentration. At 60 mM sucrose concentration, Nostoc showed the highest nitrogenase activity (0.08 ethylene ƒÊl/mg.h). The highest tolerances for the metals were present in Anabaena (0.006 ethylene ƒÊl/mg.h) for iron (20 ppm), Nodularia 0.1 ethylene ƒÊl/mg.h (for manganese 20 ppm) and Nostoc 0.96 ethylene ƒÊl/mg.h (for zinc 5 ppm)

    Improved thermal isolation of silicon suspended platforms for an all-silicon thermoelectric microgenerator based on large scale integration of Si nanowires as thermoelectric material

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    Special suspended micro-platforms have been designed as a part of silicon compatible planar thermoelectric microgenerators. Bottom-up grown silicon nanowires are going to bridge in the future such platforms to the surrounding silicon bulk rim. They will act as thermoelectric material thus configuring an all-silicon thermoelectric device. In the new platform design other additional bridging elements (usually auxiliary support silicon beams) are substituted by low conductance thin film dielectric membranes in order to maximize the temperature difference developed between both areas. These membranes follow a sieve-like design that allows fabricating them with a short additional wet anisotropic etch step. © Published under licence by IOP Publishing Ltd.Peer ReviewedPostprint (published version

    Supporting Intelligent and Trustworthy Maritime Path Planning Decisions

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    The risk of maritime collisions and groundings has dramatically increased in the past five years despite technological advancements such as GPS-based navigation tools and electronic charts which may add to, instead of reduce, workload. We propose that an automated path planning tool for littoral navigation can reduce workload and improve overall system efficiency, particularly under time pressure. To this end, a Maritime Automated Path Planner (MAPP) was developed, incorporating information requirements developed from a cognitive task analysis, with special emphasis on designing for trust. Human-in-the-loop experimental results showed that MAPP was successful in reducing the time required to generate an optimized path, as well as reducing path lengths. The results also showed that while users gave the tool high acceptance ratings, they rated the MAPP as average for trust, which we propose is the appropriate level of trust for such a system.This work was sponsored by Rite Solutions Inc., Assett Inc., Mikel Inc., and the Office of Naval Research. We would also like to thank Northeast Maritime Institute, the MIT NROTC detachment, the crew of the USS New Hampshire, and the anonymous reviewers whose comments significantly improved the paper

    The Q loops of the human multidrug resistance transporter ABCB1 are necessary to couple drug binding to the ATP catalytic cycle

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    For a primary active pump, such as the human ATP-binding-cassette (ABC) transporter ABCB1, coupling of drug-binding by the two transmembrane domains (TMDs) to the ATP catalytic cycle of the two nucleotide-binding domains (NBDs) is fundamental to the transport mechanism, but is poorly understood at the biochemical level. Structure data suggest that signals are transduced through intracellular loops of the TMDs that slot into grooves on the NBDs. At the base of these grooves is the Q loop. We therefore mutated the eponymous glutamine in one or both NBD Q loops and measured the effect on conformation and function by using a conformation-sensitive antibody (UIC2) and a fluorescent drug (Bodipy-verapamil), respectively. We showed that the double mutant is trapped in the inward-open state, which binds the drug, but cannot couple to the ATPase cycle. Our data also describe marked redundancy within the transport mechanism, because single-Q-loop mutants are functional for Bodipy-verapamil transport. This result allowed us to elucidate transduction pathways from twin drug-binding cavities to the Q loops using point mutations to favor one cavity over the other. Together, the data show that the Q loop is the central flexion point where the aspect of the drug-binding cavities is coupled to the ATP catalytic cycle.-Zolnerciks, J. K., Akkaya, B. G., Snippe, M., Chiba, P., Seelig, A., Linton, K. J. The Q loops of the human multidrug resistance transporter ABCB1 are necessary to couple drug binding to the ATP catalytic cycle

    Isoforms of U1-70k control subunit dynamics in the human spliceosomal U1 snRNP

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    Most human protein-encoding genes contain multiple exons that are spliced together, frequently in alternative arrangements, by the spliceosome. It is established that U1 snRNP is an essential component of the spliceosome, in human consisting of RNA and ten proteins, several of which are post- translationally modified and exist as multiple isoforms. Unresolved and challenging to investigate are the effects of these post translational modifications on the dynamics, interactions and stability of the particle. Using mass spectrometry we investigate the composition and dynamics of the native human U1 snRNP and compare native and recombinant complexes to isolate the effects of various subunits and isoforms on the overall stability. Our data reveal differential incorporation of four protein isoforms and dynamic interactions of subunits U1-A, U1-C and Sm-B/B’. Results also show that unstructured post- ranslationally modified C-terminal tails are responsible for the dynamics of Sm-B/B’ and U1-C and that their interactions with the Sm core are controlled by binding to different U1-70k isoforms and their phosphorylation status in vivo. These results therefore provide the important functional link between proteomics and structure as well as insight into the dynamic quaternary structure of the native U1 snRNP important for its function.This work was funded by: BBSRC (OVM), BBSRC and EPSRC (HH and NM), EU Prospects (HH), European Science Foundation (NM), the Royal Society (CVR), and fellowship from JSPS and HFSP (YM and DAPK respectively)

    A role for neuronal cAMP responsive-element binding (CREB)-1 in brain responses to calorie restriction

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    Calorie restriction delays brain senescence and prevents neurodegeneration, but critical regulators of these beneficial responses other than the NAD(+)-dependent histone deacetylase Sirtuin-1 (Sirt-1) are unknown. We report that effects of calorie restriction on neuronal plasticity, memory and social behavior are abolished in mice lacking cAMP responsive-element binding (CREB)-1 in the forebrain. Moreover, CREB deficiency drastically reduces the expression of Sirt-1 and the induction of genes relevant to neuronal metabolism and survival in the cortex and hippocampus of dietary-restricted animals. Biochemical studies reveal a complex interplay between CREB and Sirt-1: CREB directly regulates the transcription of the sirtuin in neuronal cells by binding to Sirt-1 chromatin; Sirt-1, in turn, is recruited by CREB to DNA and promotes CREB-dependent expression of target gene peroxisome proliferator-activated receptor-\u3b3 coactivator-1\u3b1 and neuronal NO Synthase. Accordingly, expression of these CREB targets is markedly reduced in the brain of Sirt KO mice that are, like CREB-deficient mice, poorly responsive to calorie restriction. Thus, the above circuitry, modulated by nutrient availability, links energy metabolism with neurotrophin signaling, participates in brain adaptation to nutrient restriction, and is potentially relevant to accelerated brain aging by overnutrition and diabetes

    Hybrid EEFIT mission to february 2023 Kahramanmaraş earthquake sequence

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    The southwestern part of Türkiye was hit on 6 February 2023 by an Mw 7.8 (epicentre:Pazarcık) and then an Mw 7.5 earthquake (epicentre: Elbistan). The event was followed by tensof thousands of aftershocks including the Mw 6.3 event on 20 February (epicentre: Uzunbağ).This paper reports on the preliminary findings of the mission organised by the UK’s EarthquakeEngineering Field Investigation Team (EEFIT) to the Kahramanmaraş Earthquake sequence ofFebruary 2023. This mission followed a hybrid model, combining field and remote investigationtechniques, to investigate the characteristics of the earthquake sequence, its impact on buildingsand infrastructure, as well as the efficacy of relief, response and recovery operations. The keymessages include that the building stock is hard to categorise which brings along difficulties withdamage assessment, that the recovery and reconstruction require multi-sectoral engagement ofkey stakeholders, and that the auditing and quality control mechanisms within the constructionindustry need revisiting in the way forward for better disaster resilience in Türkiye

    BoostingTree: parallel selection of weak learners in boosting, with application to ranking

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    Boosting algorithms have been found successful in many areas of machine learning and, in particular, in ranking. For typical classes of weak learners used in boosting (such as decision stumps or trees), a large feature space can slow down the training, while a long sequence of weak hypotheses combined by boosting can result in a computationally expensive model. In this paper we propose a strategy that builds several sequences of weak hypotheses in parallel, and extends the ones that are likely to yield a good model. The weak hypothesis sequences are arranged in a boosting tree, and new weak hypotheses are added to promising nodes (both leaves and inner nodes) of the tree using some randomized method. Theoretical results show that the proposed algorithm asymptotically achieves the performance of the base boosting algorithm applied. Experiments are provided in ranking web documents and move ordering in chess, and the results indicate that the new strategy yields better performance when the length of the sequence is limited, and converges to similar performance as the original boosting algorithms otherwise. © 2013 The Author(s)

    Prevalence and features of ICF-disability in Spain as captured by the 2008 National Disability Survey

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    <p>Abstract</p> <p>Background</p> <p>Since 1986, the study of disability in Spain has been mainly addressed by National Disability Surveys (NDSs). While international attempts to frame NDS designs within the International Classification of Functioning, Disability and Health (ICF) have progressed, in general, the ICF has hardly been used in either the NDS or epidemiological studies. This study sought to identify ICF Activity- and Participation-related content in the most recent Spanish NDS, the 2008 Survey on Disabilities, Independence and Dependency Situations (<it>Encuesta sobre discapacidades, autonomía personal y situaciones de Dependencia </it>- <it>EDAD 2008</it>), and estimate the prevalence of such ICF-framed disability.</p> <p>Methods</p> <p><it>EDAD 2008 </it>methods and questions were perused. Of the 51 EDAD items analysed, 29 were backcoded to specific d2-d7 domains of the ICF Checklist and, by rating the recorded difficulty to perform specific tasks with or without help, these were then taken as performance and capacity respectively. A global ICF score was also derived, albeit lacking data for d1, "Learning and applying knowledge", d8, "Major Life Areas" and d9, "Community, Social and Civic Life". Data were grouped by sex, age, residence and initial positive screening, and prevalence figures were calculated by disability level both for the general population, using the originally designed weights, and for the population that had screened positive to disability. Data for institutionalised persons were processed separately.</p> <p>Results</p> <p>Crude prevalence of ICF severe/complete and moderate disability among the community-dwelling population aged ≥6 years was 0.9%-2.2% respectively, and that of severe/complete disability among persons living in sheltered accommodation was 0.3%.</p> <p>Prevalence of severe/complete disability was: higher in women than in men, 0.8% vs. 0.4%; increased with age; and was particularly high in domains such as "Domestic Life", 3.4%, "Mobility", 1.8%, and "Self-care", 1.9%, in which prevalence decreased when measured by reference to performance. Moreover, global scores indicated that severe/complete disability in these same domains was frequent among the moderately disabled group.</p> <p>Conclusions</p> <p>The <it>EDAD 2008 </it>affords an insufficient data set to be ICF-framed when it comes to the Activity and Participation domains. Notwithstanding their unknown validity, ratings for available ICF domains may, however, be suitable for consideration under the ADL model of functional dependency, suggesting that there are approximately 500,000 persons suffering from severe/complete disability and 1,000,000 suffering from moderate disability, with half the latter being severely disabled in domains capable of benefiting from technical or personal aid. Application of EDAD data to the planning of services for regions and other subpopulations means that need for personal help must be assessed, unmet needs ascertained, and knowledge of social participation and support, particularly for the mentally ill, improved. International, WHO-supported co-operation in ICF planning and use of NDSs in Spain and other countries is needed.</p
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