Letters

Responses to reality, John Kramer

SA/V ratios and gaseous exchange, John Shone

Tautology and teleology John A. Horsfall     

Evaluation of Sampling-Based Methods for Sensitivity Analysis: Case Study for the E. coli Food Safety Process Risk Model

This article evaluates selected sensitivity analysis methods applicable to risk assessment models with two-dimensional probabilistic frameworks, using a microbial food safety process risk model as a test-bed. Six sampling-based sensitivity analysis methods were evaluated including Pearson and Spearman correlation, sample and rank linear regression, and sample and rank stepwise regression. In a two-dimensional risk model, the identification of key controllable inputs that can be priorities for risk management can be confounded by uncertainty. However, despite uncertainty, results show that key inputs can be distinguished from those that are unimportant, and inputs can be grouped into categories of similar levels of importance. All selected methods are capable of identifying unimportant inputs, which is helpful in that efforts to collect data to improve the assessment or to focus risk management strategies can be prioritized elsewhere. Rank-based methods provided more robust insights with respect to the key sources of variability in that they produced narrower ranges of uncertainty for sensitivity results and more clear distinctions when comparing the importance of inputs or groups of inputs. Regression-based methods have advantages over correlation approaches because they can be configured to provide insight regarding interactions and nonlinearities in the model.     

3D,Mutually Embedded MOF@Carbon Nanotube Hybrid Networks for High‐Performance Lithium‐Sulfur Batteries

Metal‐organic frameworks (MOFs) hybridized with a conductive matrix could potentially serve as a sulfur host for lithium‐sulfur (Li‐S) battery electrodes; so far most of the previously studied hybrid structures are in the powder form or thin compact films. This study reports 3D porous MOF@carbon nanotube (CNT) networks by grafting MOFs with tailored particle size uniformly throughout a CNT sponge skeleton. Growing larger‐size MOF particles to entrap the conductive CNT network yields a mutually embedded structure with high stability, and after sulfur encapsulation, it shows an initial discharge capacity of ≈1380 mA h g^?1 (at 0.1 C) and excellent cycling stability with a very low fading rate. Furthermore, owing to the 3D porous network that is suitable for enhanced sulfur loading, a remarkable areal capacity of ≈11 mA h cm^?2 (at 0.1 C) is obtained, which is much higher than other MOF‐based hybrid electrodes. The mutually embedded MOF@CNTs with simultaneously high specific capacity, areal capacity, and cycling stability represent an advanced candidate for developing high‐performance Li‐S batteries and other energy storage systems.     

Estimating the effects of non‐native species on nutrient recycling using species‐specific and general allometric models

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The farming ant Sericomyrmex amabilis nutritionally manages its fungal symbiont and its social parasite

1. When parasites exploit mutualisms involving food exchange, they can destabilise the partnership with costs to interacting partners. For instance, the ant Sericomyrmex amabilis farms fungal symbionts to produce food, but, in so doing, attracts parasitic Megalomyrmex symmetochus guest ants that infiltrate fungus‐farming ant societies and live with their hosts their entire lives. 2. The present study examined whether host foraging in parasitised colonies shifts towards nutritional requirements of the parasitic guest ants as inferred from the parasite's elemental content (%C, %N, and C:N). 3. Laboratory feeding experiments with nutritionally defined diets indicated that S. amabilis ants harvest protein‐biased substrate, and more total substrate when hosting M. symmetochus relative to when provisioning their fungus gardens and nestmates. 4. Field surveys further showed that parasitised colonies incur reductions in fungus garden nutritional quality and quantity, brood mass, and host worker body condition. And yet these costs appear manageable across growing seasons, as parasitised fungal cultivars appear to provide sufficient nutrition for stable populations of host ants. 5. The approach developed here shows how behavioural strategies for nutrient regulation can extend beyond the needs of the individual to entire fungus‐farming systems, and implies that S. amabilis dynamically adjusts collective foraging strategies when parasitised to enhance long‐term symbiotic stability.     

Effects of organic pH buffers on a cell growth and an antibody production of human-human hybridoma HB4C5 cells in a serum-free culture

Human-human hybridoma cells secreting a human monoclonal antibody were cultured in a serum-free medium containing various organic pH buffers in order to clarify their effects on cell growth and antibody production. Organic pH buffers having either one sulfonic acid and several acyclic amine moieties, or several cyclic amine moieties containing two amino nitrogen did not inhibit cell growth; while other organic buffers sulfonic acid moiety plus several cyclic amine moieties containing one amino nitrogen slightly decreased cell growth, but enhanced antibody production. Using Fujita's organic conceptual diagram, a relationship between the organicity and inorganicity of a pH buffer to cell growth and antibody production was found. pH buffers with large inorganicity and small organicity values were favorable for cell growth, and buffers with small inorganicity and large organicity values were preferred to enhance antibody production. Although the pH buffering range affects cell growth, its effect on antibody production is not clear. In conclusion, 2-morpholinoethanesulfonic acid (MES), 3-morpholino-propanesulfonic acid (MOPS) and 1, 2-N, N-bis[N, N-di(2-sulfonoethyl)piperazinyl]ethane (Bis-PIPES) are shown to be the most optimal of the buffers tested, because they enhanced antibody production without decreasing the cell growth among the pH buffers tested here.     

Multiple‐stressor effects on stream invertebrates: a mesocosm experiment manipulating nutrients,fine sediment and flow velocity

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Identification of a novel class of conotoxins defined as V-conotoxins with a unique cysteine pattern and signal peptide sequence

Cone snails are predatory gastropod mollusks distributed in all tropical marine habitats with a highly sophisticated defense strategy using small peptides in their venoms. Here, we report the discovery and initial characterization of the V-superfamily conotoxins. A novel conotoxin vi15a was purified from the venom of a worm-hunting species Conus virgo. The sequence of vi15a was determined to have a unique arrangement of cysteine residues (C-C-CC-C-C-C-C), which defines the new V-superfamily conotoxins. The cDNA of vi15a was cloned with RACE method. Its unique signal peptide sequence led to the cloning of another V-superfamily conotoxin, Vt15.1, from Conus vitulinus. These results, as well as the existence of Lt15.1 from Conus litteratus and ca15a from Conus caracteristicus with the same cysteine pattern, suggest that V-superfamily might be a large and diverse group of peptides widely distributed in different Conus species. Like other eight Cys-containing toxins, V-superfamily conotoxins might also adopt an “ICK+1” disulfide bond connectivity. The identification of this novel class of conotoxins will certainly improve our understanding of the structure diversity of disulfide rich toxins.     

构建我国生物多样性评价的指标体系

生物多样性指标体系的建设过程长期而复杂,需要结合科学研究、监测以及决策制定,并基于合理的结构进行指标设计.构建适宜的生物多样性评价指标体系、监测评估生物多样性状况及变化趋势,已被纳入我国国家生物多样性战略及其行动计划.本文结合国内外经验,从指标的逻辑框架、空间尺度、时间尺度、指标类型、评价方法等5个方面探讨了指标体系构...     

Towards a resource‐based habitat approach for spatial modelling of vector‐borne disease risks

Given the veterinary and public health impact of vector‐borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the pathogen. Empirical–statistical methods do not explicitly incorporate biological mechanisms, whereas current mechanistic models are rarely spatially explicit; both methods ignore the way animals use the landscape (i.e. movement ecology). We argue that applying a functional concept for habitat, i.e. the resource‐based habitat concept (RBHC), can solve these issues. The RBHC offers a framework to identify systematically the different ecological resources that are necessary for the completion of the transmission cycle and to relate these resources to (combinations of) landscape features and other environmental factors. The potential of the RBHC as a framework for identifying suitable habitats for vector‐borne pathogens is explored and illustrated with the case of bluetongue virus, a midge‐transmitted virus affecting ruminants. The concept facilitates the study of functional habitats of the interacting species (vectors as well as hosts) and provides new insight into spatial and temporal variation in transmission opportunities and exposure that ultimately determine disease risks. It may help to identify knowledge gaps and control options arising from changes in the spatial configuration of key resources across the landscape. The RBHC framework may act as a bridge between existing mechanistic and statistical modelling approaches.