1,616 research outputs found
Literature review of physical and chemical pretreatment processes for lignocellulosic biomass
Different pretreatment technologies published in public literature are described in terms of the mechanisms involved, advantages and disadvantages, and economic assessment. Pretreatment technologies for lignocellulosic biomass include biological, mechanical, chemical methods and various combinations thereof. The choice of the optimum pretreatment process depends very much on the objective of the biomass pretreatment, its economic assessment and environmental impact. Only a small number of pretreatment methods has been reported as being potentially cost-effective thus far. These include steam explosion, liquid hot water, concentrated acid hydrolysis and dilute acid pretreatments
Strong Modification of the Nonlinear Optical Response of Metallic Subwavelength Hole Arrays
The influence of hole shape on the nonlinear optical properties of metallic subwavelength hole arrays is investigated. It is found that the amount of second harmonics generated can be enhanced by changing the hole shape. In part this increase is a direct result of the effect of hole shape on the linear transmission properties. Remarkably, in addition to enhancements that follow directly from the linear properties of the array, we find a hot hole shape. For rectangular holes the effective nonlinear response is enhanced by more than 1 order of magnitude for one particular aspect ratio. This enhancement can be attributed to slow propagation of the fundamental wavelength through the holes which occurs close to the hole cutoff
Using continuous-time spatial capture–recapture models to make inference about animal activity patterns
This work was part‐funded by EPSRC Grant EP/I000917/1, by the research fellowship RF‐2018‐213/9, and the fieldwork was funded by the Summerlee Foundation and Panthera.1. Quantifying the distribution of daily activity is an important component of behavioral ecology. Historically, it has been difficult to obtain data on activity patterns, especially for elusive species. However, the development of affordable camera traps and their widespread usage has led to an explosion of available data from which activity patterns can be estimated. 2. Continuous-time spatial capture?recapture (CT SCR) models drop the occasion structure seen in traditional spatial and nonspatial capture?recapture (CR) models and use the actual times of capture. In addition to estimating density, CT SCR models estimate expected encounters through time. Cyclic splines can be used to allow flexible shapes for modeling cyclic activity patterns, and the fact that SCR models also incorporate distance means that space-time interactions can be explored. This method is applied to a jaguar dataset. 3. Jaguars in Belize are most active and range furthest in the evening and early morning and when they are located closer to the network of trails. There is some evidence that females have a less variable pattern than males. The comparison between sexes demonstrates how CT SCR can be used to explore hypotheses about animal behavior within a formal modeling framework. 4. SCR models were developed primarily to estimate and model density, but the models can be used to explore processes that interact across space and time, especially when using the CT SCR framework that models the temporal dimension at a finer resolution.Publisher PDFPeer reviewe
Studies on the Induction of Antigen-Specific Antibody in Anti-CD40 Cultured Human B Lymphocytes
Costimulatory signals provided by T cells are required for B cells to produce specific antibody to T-dependent antigen. We have investigated the suitability of using the CD40 culture system for the proliferation and differentiation of Ag-specific human B cells using cytomegalovirus (CMV) or tetanus toxoid (TT) as antigen. We modified the CD40 culture system (CD32- transfected L cells, anti-CD40, and IL-4) by applying a sequential cytokine stimulation and compared total B-cell cultures with antigen-specific B cells preselected by panning. The detection of specific antibody became possible when antigen-selected B cells were cultured for 7 days in the CD40 system to induce clonal expansion, followed by the addition of IL-2 and IL10 for an additional 7 days to induce plasma-cell differentiation. We conclude that our intial inability to detect specific antibody in the CD40 system is due to overgrowth of nonspecific B cell clones and that selection of antigen-specific B cells by panning overcomes this problem. Induction of antigen-specific antibody production was found to be optimal when the initial
contact with antigen during panning was limited to between 1 to 24 hours
Open population maximum likelihood spatial capture-recapture
Funding: Part-funded by UK EPSRC grant EP/K041061/1 (DB); Richard Glennie was funded by the Carnegie Trust.Open population capture‐recapture models are widely used to estimate population demographics and abundance over time. Bayesian methods exist to incorporate open population modeling with spatial capture‐recapture (SCR), allowing for estimation of the effective area sampled and population density. Here, open population SCR is formulated as a hidden Markov model (HMM), allowing inference by maximum likelihood for both Cormack‐Jolly‐Seber and Jolly‐Seber models, with and without activity center movement. The method is applied to a 12‐year survey of male jaguars (Panthera onca) in the Cockscomb Basin Wildlife Sanctuary, Belize, to estimate survival probability and population abundance over time. For this application, inference is shown to be biased when assuming activity centers are fixed over time, while including a model for activity center movement provides negligible bias and nominal confidence interval coverage, as demonstrated by a simulation study. The HMM approach is compared with Bayesian data augmentation and closed population models for this application. The method is substantially more computationally efficient than the Bayesian approach and provides a lower root‐mean‐square error in predicting population density compared to closed population models.PostprintPeer reviewe
A convenient and versatile culturomics platform to expand the human gut culturome of Lachnospiraceae and Oscillospiraceae
Acknowledgements N.P. was supported by a grant from the Graduate School of Medical Sciences of the University of Groningen, the Netherlands. L.L. was supported by a joint fellowship from the University Medical Center Groningen and the China Scholarship Council (CSC) (grant number CSC201908320432). A.W.W. and the Rowett Institute receive core funding support from the Scottish Government’s Rural and Environmental Science and Analytical Services (RESAS) division. The funders played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript.Peer reviewe
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