Feeding preferences of the herbivorous crab Grapsus albolineatus: The differential influence of algal nutrient content and morphology

The tropical rocky shore crab Grapsus albolineatus selectively consumes rare filamentous algae over more abundant foliose algae during the winter in Hong Kong. Laboratory experiments have shown that growth of G. albolineatus is enhanced and mortality reduced when given a diet of filamentous algae as opposed to foliose algae. In the laboratory, G. albolineatus consumed filamentous algae (Enteromorpha clathrata, Hincksia mitchelliae and Chaetomorpha antennina) in greater amounts than any foliose algae (Dermonema frappieri, Pterocladia tenuis, Porphyra suborbiculata, Ulva fasciata, Endarachne binghamiae) in both multiple choice and no choice experiments. The most energy-rich alga was Pterocladia, while Porphyra had the highest protein content. Filamentous algae had lower overall nutrient contents than foliose algae. Consumption rates for Enteromorpha and Hincksia were, however, sufficiently higher than for Porphyra, which ensured that the net intake of nutrients per day was greater. Even though protein assimilation efficiency was higher for Porphyra than Hincksia, G. albolineatus assimilated more protein, per day, from Hincksia. When the confounding effects of morphology and nutrient value were separated, by offering the crab choices of commercially available algae (Laminaria sp.) cut into different forms (foliose and filamentous), G. albolineatus showed a strong preference for the filamentous form, despite both forms having the same nutrient value Preference for filamentous forms is likely to be constrained by the morphology of the chelae, which have delicate tips, and appear unable to tear foliose algae Algal morphology, therefore, appears to be of prime importance and the nutrient content and digestibility of algae of secondary importance in determining the feeding preferences of G. albolineatus. The high consumption rate of filamentous algae outweighs their relative nutrient deficiencies, indicating that they are better suited to meeting the physiological needs of the crab than foliose algae.published_or_final_versio

A simplified biomimetic temperature logger for recording intertidal barnacle body temperatures

published_or_final_versio

How to do realistic political theory (and why you might want to)

In recent years, a number of realist thinkers have charged much contemporary political theory with being idealistic and moralistic. While the basic features of the realist counter-movement are reasonably well understood, realism is still considered a critical, primarily negative creed which fails to offer a positive, alternative way of thinking normatively about politics. Aiming to counteract this general perception, in this article I draw on Bernard Williams’s claims about how to construct a politically coherent conception of liberty from the non-political value of freedom. I do this because Williams’s argument provides an illuminating example of the distinctive nature of realist political thinking and its attractions. I argue that Williams’s account of realist political thinking challenges the orthodox moralist claim that normative political arguments must be guided by an ideal ethical theory. I then spell out the repercussions Williams’s claims about the significance of political opposition and non-moralised accounts of motivation have for our understanding of the role and purpose of political theory. I conclude by defending the realist claim that action-guiding political theory should accordingly take certain features of our politics as given, most centrally the reality of political opposition and the passions and experiences that motivate them. On this reading political realism offers a viable way of thinking about political values which cannot be understood in terms of the categories of intellectual separation – ideal/nonideal or fact-insensitive/fact-sensitive – that have marked political theory in recent years

Principles of Stakes Fairness in Sport

Fairness in sport is not just about assigning the top prizes to the worthiest competitors. It is also about the way the prize structure itself is organised. For many sporting competitions, although it may be acceptable for winners to receive more than losers, it can seem unfair for winners to take everything and for losers to get nothing. Yet this insight leaves unanswered some difficult questions about what stakes fairness requires and which principles of stakes fairness are appropriate for particular competitions. In this article I specify a range of different principles of stakes fairness (ten in total) that could regulate sporting competitions. I also put forward a theoretical method for pairing up appropriate principles of stakes fairness with given sporting competitions. Specifically, I argue that the underlying rationales for holding sporting competitions can provide useful guides for identifying appropriate principles of stakes fairness. I then seek to clarify and work through some of the implications of this method for a sample of real world controversies over sporting prize structures. I also attempt to refine the method in response to two possible objections from indeterminacy and relativism. Finally, I compare and contrast my conclusions with more general philosophical debates about justice

The conceptual and practical ethical dilemmas of using health discussion board posts as research data.

Increasing numbers of people living with a long-term health condition are putting personal health information online, including on discussion boards. Many discussion boards contain material of potential use to researchers; however, it is unclear how this information can and should be used by researchers. To date there has been no evaluation of the views of those individuals sharing health information online regarding the use of their shared information for research purposes

Determining the best method for first-line assessment of neonatal blood glucose levels

Objective: To evaluate and compare the accuracy and performance of two electrochemical glucose meters. To determine the user acceptability of these glucose meters and the ABL 620 Blood Gas Analyser (Radiometer, Copenhagen, Denmark) with an electrochemical glucose oxidase electrode for use in a Level 2 special care baby unit

Recurrent Modification of a Conserved Cis-Regulatory Element Underlies Fruit Fly Pigmentation Diversity

The development of morphological traits occurs through the collective action of networks of genes connected at the level of gene expression. As any node in a network may be a target of evolutionary change, the recurrent targeting of the same node would indicate that the path of evolution is biased for the relevant trait and network. Although examples of parallel evolution have implicated recurrent modification of the same gene and cis-regulatory element (CRE), little is known about the mutational and molecular paths of parallel CRE evolution. In Drosophila melanogaster fruit flies, the Bric-à-brac (Bab) transcription factors control the development of a suite of sexually dimorphic traits on the posterior abdomen. Female-specific Bab expression is regulated by the dimorphic element, a CRE that possesses direct inputs from body plan (ABD-B) and sex-determination (DSX) transcription factors. Here, we find that the recurrent evolutionary modification of this CRE underlies both intraspecific and interspecific variation in female pigmentation in the melanogaster species group. By reconstructing the sequence and regulatory activity of the ancestral Drosophila melanogaster dimorphic element, we demonstrate that a handful of mutations were sufficient to create independent CRE alleles with differing activities. Moreover, intraspecific and interspecific dimorphic element evolution proceeded with little to no alterations to the known body plan and sex-determination regulatory linkages. Collectively, our findings represent an example where the paths of evolution appear biased to a specific CRE, and drastic changes in function were accompanied by deep conservation of key regulatory linkages. © 2013 Rogers et al

The Effect Of Breastfeeding On Child Development At 5 Years: A Cohort Study

Objective It is uncertain to what degree the relationship between breastfeeding and later cognitive development is a true biological effect, or is confounded by psychosocial factors. The study aim was to further investigate this relationship and the effect of duration of breast feeding on cognitive development. Methods A total of 3880 children were followed from birth. Breastfeeding duration was measured by questionnaire at 6 months of age and a Peabody Picture Vocabulary Test Revised (PPVT-R) was administered at 5 years. PPVT-R scores were adjusted for the effects of a large array of biological and psychosocial confounders. The relationship between breastfeeding and the mean PPVT-R scores were examined using analysis of variance and multiple linear regression. Results A strong positive relationship was demonstrated between breastfeeding and the PPVT-R scores with increasing scores with increased duration of breastfeeding. After adjusting for a wide range of biological and social factors, the adjusted mean for those breastfed for 6 months or more was 8.2 points higher for females and 5.8 points for males when compared to those never breastfed. Conclusion These findings suggest a significant benefit to child development is conferred by breastfeeding and is related independently to longer periods of breastfeeding

Atomic excitation during recollision-free ultrafast multi-electron tunnel ionization

Modern intense ultrafast pulsed lasers generate an electric field of sufficient strength to permit tunnel ionization of the valence electrons in atoms. This process is usually treated as a rapid succession of isolated events, in which the states of the remaining electrons are neglected. Such electronic interactions are predicted to be weak, the exception being recollision excitation and ionization caused by linearly-polarized radiation. In contrast, it has recently been suggested that intense field ionization may be accompanied by a two-stage `shake-up' reaction. Here we report a unique combination of experimental techniques that enables us to accurately measure the tunnel ionization probability for argon exposed to 50 femtosecond laser pulses. Most significantly for the current study, this measurement is independent of the optical focal geometry, equivalent to a homogenous electric field. Furthermore, circularly-polarized radiation negates recollision. The present measurements indicate that tunnel ionization results in simultaneous excitation of one or more remaining electrons through shake-up. From an atomic physics standpoint, it may be possible to induce ionization from specific states, and will influence the development of coherent attosecond XUV radiation sources. Such pulses have vital scientific and economic potential in areas such as high-resolution imaging of in-vivo cells and nanoscale XUV lithography.Comment: 17 pages, 4 figures, original format as accepted by Nature Physic

Representations of an integer by some quaternary and octonary quadratic forms

In this paper we consider certain quaternary quadratic forms and octonary quadratic forms and by using the theory of modular forms, we find formulae for the number of representations of a positive integer by these quadratic forms.Comment: 20 pages, 4 tables. arXiv admin note: text overlap with arXiv:1607.0380