23,861 research outputs found

    Large centric diatoms allocate more cellular nitrogen to photosynthesis to counter slower RUBISCO turnover rates

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    © 2014 Wu, Jeans, Suggett, Finkel and Campbell. Diatoms contribute ~40% of primary production in the modern ocean and encompass the largest cell size range of any phytoplankton group. Diatom cell size influences their nutrient uptake, photosynthetic light capture, carbon export efficiency, and growth responses to increasing pCO2. We therefore examined nitrogen resource allocations to the key protein complexes mediating photosynthesis across six marine centric diatoms, spanning 5 orders of magnitude in cell volume, under past, current and predicted future pCO2 levels, in balanced growth under nitrogen repletion. Membrane bound photosynthetic protein concentrations declined with cell volume in parallel with cellular concentrations of total protein, total nitrogen and chlorophyll. Larger diatom species, however, allocated a greater fraction (by 3.5-fold) of their total cellular nitrogen to the soluble Ribulose-1,5-bisphosphate Carboxylase Oxygenase (RUBISCO) carbon fixation complex than did smaller species. Carbon assimilation per unit of RUBISCO large subunit (C RbcL-1 s-1) decreased with cell volume, from ~8 to ~2 C RbcL-1 s-1 from the smallest to the largest cells. Whilst a higher allocation of cellular nitrogen to RUBISCO in larger cells increases the burden upon their nitrogen metabolism, the higher RUBISCO allocation buffers their lower achieved RUBISCO turnover rate to enable larger diatoms to maintain carbon assimilation rates per total protein comparable to small diatoms. Individual species responded to increased pCO2, but cell size effects outweigh pCO2 responses across the diatom species size range examined. In large diatoms a higher nitrogen cost for RUBISCO exacerbates the higher nitrogen requirements associated with light absorption, so the metabolic cost to maintain photosynthesis is a cell size-dependent trait

    Beyond Correlation Filters: Learning Continuous Convolution Operators for Visual Tracking

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    Discriminative Correlation Filters (DCF) have demonstrated excellent performance for visual object tracking. The key to their success is the ability to efficiently exploit available negative data by including all shifted versions of a training sample. However, the underlying DCF formulation is restricted to single-resolution feature maps, significantly limiting its potential. In this paper, we go beyond the conventional DCF framework and introduce a novel formulation for training continuous convolution filters. We employ an implicit interpolation model to pose the learning problem in the continuous spatial domain. Our proposed formulation enables efficient integration of multi-resolution deep feature maps, leading to superior results on three object tracking benchmarks: OTB-2015 (+5.1% in mean OP), Temple-Color (+4.6% in mean OP), and VOT2015 (20% relative reduction in failure rate). Additionally, our approach is capable of sub-pixel localization, crucial for the task of accurate feature point tracking. We also demonstrate the effectiveness of our learning formulation in extensive feature point tracking experiments. Code and supplementary material are available at http://www.cvl.isy.liu.se/research/objrec/visualtracking/conttrack/index.html.Comment: Accepted at ECCV 201

    Novel concepts in virally induced asthma

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    Viruses are the predominant infectious cause of asthma exacerbations in the developed world. In addition, recent evidence strongly suggests that viral infections may also have a causal role in the development of childhood asthma. In this article, we will briefly describe the general perception of how the link between infections and asthma has changed over the last century, and then focus on very recent developments that have provided new insights into the contribution of viruses to asthma pathogenesis. Highlighted areas include the contribution of severe early life viral infections to asthma inception, genetic determinants of severe viral infections in infancy, the differences in innate and adaptive immune system cytokine responses to viral infection between asthmatic and nonasthmatic subjects, and a potential vaccine strategy to prevent severe early life virally-induced illness

    Harnessing optical micro-combs for microwave photonics

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    In the past decade, optical frequency combs generated by high-Q micro-resonators, or micro-combs, which feature compact device footprints, high energy efficiency, and high-repetition-rates in broad optical bandwidths, have led to a revolution in a wide range of fields including metrology, mode-locked lasers, telecommunications, RF photonics, spectroscopy, sensing, and quantum optics. Among these, an application that has attracted great interest is the use of micro-combs for RF photonics, where they offer enhanced functionalities as well as reduced size and power consumption over other approaches. This article reviews the recent advances in this emerging field. We provide an overview of the main achievements that have been obtained to date, and highlight the strong potential of micro-combs for RF photonics applications. We also discuss some of the open challenges and limitations that need to be met for practical applications.Comment: 32 Pages, 13 Figures, 172 Reference

    Human induced pluripotent stem cells for modelling metabolic perturbations and impaired bioenergetics underlying cardiomyopathies

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    Normal cardiac contractile and relaxation function are critically dependent on a continuous energy supply. Accordingly, metabolic perturbations and impaired mitochondrial bioenergetics with subsequent disruption of ATP production underpin a wide variety of cardiac diseases, including diabetic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, anthracycline cardiomyopathy, peripartum cardiomyopathy, and mitochondrial cardiomyopathies. Crucially, there are no specific treatments for preventing the onset or progression of these cardiomyopathies to heart failure, one of the leading causes of death and disability worldwide. Therefore, new treatments are needed to target the metabolic disturbances and impaired mitochondrial bioenergetics underlying these cardiomyopathies in order to improve health outcomes in these patients. However, investigation of the underlying mechanisms and the identification of novel therapeutic targets have been hampered by the lack of appropriate animal disease models. Furthermore, interspecies variation precludes the use of animal models for studying certain disorders, whereas patient-derived primary cell lines have limited lifespan and availability. Fortunately, the discovery of human induced pluripotent stem cells (hiPSCs) has provided a promising tool for modelling cardiomyopathies via human heart tissue in a dish. In this review article, we highlight the use of patient-derived iPSCs for studying the pathogenesis underlying cardiomyopathies associated with metabolic perturbations and impaired mitochondrial bioenergetics, as the ability of iPSCs for self-renewal and differentiation makes them an ideal platform for investigating disease pathogenesis in a controlled in vitro environment. Continuing progress will help elucidate novel mechanistic pathways, and discover novel therapies for preventing the onset and progression of heart failure, thereby advancing a new era of personalised therapeutics for improving health outcomes in patients with cardiomyopathy

    Surveying adjustment datum and relative deformation accuracy analysis

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    In the surveying adjustment, unknown parameters are usually not direct observations, but the elements related to these direct observations. In order to determine the unknown parameters adequate known data should be provided, and these necessarily required known data are used to form the adjustment datum. Under different datums, different results will be obtained even with the same direct observations. However, in the practical adjustment calculation, the datum and its effect on the results are always ignored. In this paper, the adjustment datum is firstly discussed and defined as datum equations. Then an adjustment method based on the datum equations and least squares is presented. This method is a generic one, not only suited for the case in an ordinary datum but also in the gravity centre datum or a quasi-datum, and can be easily used to analyse different deformations. Based on this method, the transformation between different reference frames is derived. It shows that the calculation results, deformation and positioning accuracy under one kind of datum are relative and generic. A case study is further introduced and used to test this new method. Based on the case study, the conclusions are reached. It is found that the relative positional root mean square error of each point becomes bigger as the distance between the point and the datum increases, and the relative deformation offsets under different kinds of datum are helpful for reliable deformation analysis

    Schizophrenia trials in China: a survey

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    OBJECTIVE: China's biomedical research activity is increasing and this literature is becoming more accessible online. Our aim was to survey all randomized control schizophrenia trials (RCTs) in one Chinese bibliographic database. METHOD: Chinese Academic Journals was electronically searched for RCTs and all relevant citations were also sought on PubMed to ascertain global accessibility. RESULTS: The search identified 3275 records, of which 982 were RCTs relevant to schizophrenia. A total of 71% (699) could be found by using English phrases. All the main body of text of the 982 papers was in Mandarin. On average, these trials involved about 100 people, with interventions and outcome measures familiar to schizophrenia trialists worldwide. Four of the 982 records (<1%) were identified on PubMed. CONCLUSION: Those undertaking systematic reviews should search the Chinese literature for relevant material. Failing to do this will leave the results of systematic reviews prone to random error or bias, or both

    Challenges in biogas production from anaerobic membrane bioreactors

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    © 2016 Spectacular applications of anaerobic membrane bioreactors (AnMBRs) are emerging due to the membrane enhanced biogas production in the form of renewable bioresources. They produce similar energy derived from the world's depleting natural fossil energy sources while minimizing greenhouse gas (GHG) emissions. During the last decade, many types of AnMBRs have been developed and applied so as to make biogas technology practical and economically viable. Referring to both conventional and advanced configurations, this review presents a comprehensive summary of AnMBRs for biogas production in recent years. The potential of biogas production from AnMBRs cannot be fully exploited, since certain constraints still remain and these cause low methane yield. This paper addresses a detailed assessment on the potential challenges that AnMBRs are encountering, with a major focus on many inhibitory substances and operational dilemmas. The aim is to provide a solid platform for advances in novel AnMBRs applications for optimized biogas production
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