Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

The ancient notion of self-preservation in the theories of Hobbes and Spinoza

Over the course of four sections this PhD examines the ways in which the Aristotelian, Stoic and Epicurean philosophers portray bodily activity. In particular, it argues that their claims regarding bodies' natural tendency to preserve themselves, and seek out the goods capable of promoting their well-being, came to influence Hobbes's and Spinoza's later accounts of natural, animal and social behaviour. The first section presents the ancient accounts of natural and animal bodily tendencies and explores the specific ways in which the Aristotelian, Stoic and Epicurean views on animal desires came to complement and diverge from each other. After investigating the perceived links between natural philosophy, psychology and ethics, the section proceeds to consider how the ancients used this 'unified' view of nature to guide their accounts of the soul's primary appetites and desires. Also examined is the extent to which civil society is portrayed as a means of securing the individual against others, and how Aristotelian philia, Theophrastian oikeiotês and Stoic oikeiōsis came to stand in opposition to the fear-driven and compact-based accounts of social formation favoured by the Epicureans. The second section considers how the ancient accounts of impulsive behaviour and social formation were received and diffused via new editions of ancient texts, eclectic readings of Aristotle, and the attempts of Neostoic and Neoepicurean authors to update and systematise those philosophies from the late sixteenth century onwards. The particular treatments of Hellenistic thought by authors such as Justus Lipsius, Hugo Grotius and Pierre Gassendi are considered in detail and are placed within the context of the growing trend to use Stoic and Epicurean thought to replace the authority of Aristotle in the areas of science, psychology, and politics. The final two sections are devoted respectively to considering the ways in which Hobbes and Spinoza encountered the Hellenistic accounts of bodies and demonstrating how these earlier accounts came to feature in each of their own discussions of bodily tendencies. Engaging with a wide range of their texts, each section develops the many nuances and contours that emerged as both writers developed and fine-tuned their accounts of bodily actions. This reveals the many ways in which the ancient accounts of self-preservation helped to unify large aspects of Hobbes's and Spinoza's own philosophical corpus, while equally showing how a well-developed account of bodily tendencies might challenge the scholastic worldview and expand further the boundaries of the so-called 'New Science'.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Natural law:law, rights and duties

The chapter gives an overview of natural law and natural rights from ancient Greece and Rome to modern discussions. It suggests that when the subject is considered as a topic in intellectual history as distinct from the history of philosophy, it is problematic to consider it as a coherent phenomenon. The implication of taking a purely historical approach to natural law and natural rights is that the subject breaks up into a series of episodes with varying family resemblances. These similarities are generally perceived in light of the argumentative and rhetorical needs of subsequent periods, and this applies also in the case of many modern invocations of the history of natural law and natural rights. However, there is now a substantial and flourishing scholarly literature that seeks to establish more adequate historical readings of the disparate occurrences that are bundled together as natural law and natural rights. Drawing on this literature, the chapter outlines some of the prominent historical episodes

Industrial water treatment

Dispersal knowledge is essential for conservation management, and demand is growing. But are we accumulating dispersal knowledge at a pace that can meet the demand? To answer this question we tested for changes in dispersal data collection and use over time. Our systematic review of 655 conservation-related publications compared five topics: climate change, habitat restoration, population viability analysis, land planning (systematic conservation planning) and invasive species. We analysed temporal changes in the: (i) questions asked by dispersal-related research; (ii) methods used to study dispersal; (iii) the quality of dispersal data; (iv) extent that dispersal knowledge is lacking, and; (v) likely consequences of limited dispersal knowledge. Research questions have changed little over time; the same problems examined in the 1990s are still being addressed. The most common methods used to study dispersal were occupancy data, expert opinion and modelling, which often provided indirect, low quality information about dispersal. Although use of genetics for estimating dispersal has increased, new ecological and genetic methods for measuring dispersal are not yet widely adopted. Almost half of the papers identified knowledge gaps related to dispersal. Limited dispersal knowledge often made it impossible to discover ecological processes or compromised conservation outcomes. The quality of dispersal data used in climate change research has increased since the 1990s. In comparison, restoration ecology inadequately addresses large-scale process, whilst the gap between knowledge accumulation and growth in applications may be increasing in land planning. To overcome apparent stagnation in collection and use of dispersal knowledge, researchers need to: (i) improve the quality of available data using new approaches; (ii) understand the complementarities of different methods and; (iii) define the value of different kinds of dispersal information for supporting management decisions. Ambitious, multi-disciplinary research programs studying many species are critical for advancing dispersal research

Number of papers reviewed in each topic and time period.

<p>Time periods include Old (1990–2000) and New (2010–2012), with dates of each time period indicated (number of papers identified using search terms and number we reviewed in parenthesis). Search terms for topics are in addition to the search terms for dispersal (see text).</p

Effects related to the five research questions.

<p>For factors that varied with topic, time or their interaction: the method used to obtain dispersal data (A-C); the quality of the dispersal data, including relevance (D); dispersal statistic (E, F); and sample size (G); dispersal knowledge gaps (H); non-dispersal knowledge gaps (I); consequences for the study (J), and; consequences for management (K-M). Error bars indicate 95% confidence limits.</p