The population dynamics and growth of the freshwater crayfish Austvopotamobius pallipes in an aqueduct in Northumbria

Despite the wide distribution and abundance of the freshwater crayfish Austropotcmobius pallipes in Britain, little is known of its population biology. The dynamics and growth of a Northumbrian population of A. pallipes were studied using an intensive-mark- recapture programme. The seasonal timing of moulting and reproduction was found to be predictable and probably related to water temperature. Stomach contents showed crayfish to be omnivorous, with plant material forming the bulk of the diet. Population size, survival and recruitment were estimated from mark- recapture data at frequent intervals. Two principal types of mortality were identified: moult-associated mortality, which was relatively intense and of short (2-3 weeks) duration, and overwinter mortality, which operated at a much lower estimated weekly rate over a period of some 30 weeks. Mortality was shown to be highly variable throughout the year. Population size generally showed a midsummer peak as recruitment into the catchable size classes occurred. Thereafter numbers declined slightly towards the end of the growth season, followed by an overwinter decline of some 50% of total numbers. Longevity was estimated to be at least eleven years. The relationship between size, age and weight was established and males shown to have faster growth rates than females after the size of sexual maturity. Growth increments and moult frequency were shown to differ between the sexes and according to body size. Reproductive females omitted one moult while carrying eggs. Growth rates were depressed by the parasite Thelohania oonteoeani and by the regeneration of a major chela. The fecundity of females and the probability of being reproductive increased with body size. The annual production of the study population was estimated at 196.49 kg ha(^-1) in 1977, 116.80 kg ha(^-1) in 1978 and 87.79 kg ha(^-1) in 1979. Detailed life histories of many marked individuals were collected which support the conclusions drawn at the population level

Optical Design for Li Beam Zeeman Polarimetry Measurements on Diii-D

Measurements of the magnetic field pitch angle are obtained from the polarization characteristics of the {sigma} component of the Zeeman triplet of Li emission at 670.8 nm. A four element optical system images a horizontal Li beam on an array of 3 x 32, 1 mm diam. optical fibers, providing 32 spatial channels with 5 mm radial resolution in the plasma. Low Verdet constant glass is used for all optical elements near the DIII-D vessel to minimize the effects of Faraday rotation caused by stray magnetic fields. Before entering the fiber optics, the light passes through two crossed (45 degrees) photoelastic modulators (PEM) and a linear polarizer, which convert the various polarization states into an intensity modulated signal at the fundamental and 2nd harmonic of the PEM frequencies. For each spatial channel, light from a three fiber bundle is collimated and passes through a temperature tuned etalon (free spectral range, FSR = 0.3 nm; finesse, F = 5.7) in order to select only one {sigma} line of the triplet. The FSR is large enough to adequately cover the expected Zeeman triplet and small enough to achieve a low bandwidth (0.06 nm) at reasonably low F. A 1.0 nm wide interference filter is used to block all but 4-5 peaks of the etalon. The light is then focused on GaAs photo multiplier detectors. Details of the design and performance are presented

Activation of the glycosyl-phosphatidylinositol-anchored membrane dipeptidase upon release from pig kidney membranes by phospholipase C

Incubation of pig kidney microvillar membranes with Bacillus thuringiensis or Staphylococcus aureus phosphatidylinositol-specific phospholipase C (PI-PLC) resulted in the release of a number of glycosyl-phosphatidylinositol (GPI)-anchored hydrolases, including alkaline phosphatase (EC 3.1.3.1), amino-peptidase P (EC 3.4.11.9), membrane dipeptidase (EC 3.4.13.19), 5'-nucleotidase (EC 3.1.3.5) and trehalase (EC 3.2.1.28). Of these five ectoenzymes only for membrane dipeptidase was there a significant (approx. 100%) increase in enzymic activity upon release from the membrane. Maximal activation occurred at a PI-PLC concentration 10-fold less than that required for maximal release. In contrast solubilization of the membranes with n-octyl beta-D-glucopyranoside had no effect on the enzymic activity of membrane dipeptidase. A competitive e.l.i.s.a. with a polyclonal antiserum to membrane dipeptidase indicated that the increase in enzymic activity was not due to an increase in the amount of membrane dipeptidase protein. Although PI-PLC cleaved the GPI anchor of the affinity-purified amphipathic form of pig membrane dipeptidase there was no concurrent increase in enzymic activity. In the absence of PI-PLC, membrane dipeptidase in the microvillar membranes hydrolysed Gly-D-Phe with a Km of 0.77 mM and a Vmax. of 602 nmol/min per mg of protein. However, in the presence of a concentration of PI-PLC which caused maximal release from the membrane and maximal activation of membrane dipeptidase the Km was decreased to 0.07 mM while the Vmax. remained essentially unchanged at 624 nmol/min per mg of protein. Overall these results suggest that cleavage by PI-PLC of the GPI anchor on membrane dipeptidase may relax conformational constraints on the active site of the enzyme which exist when it is anchored in the lipid bilayer, thus resulting in an increase in the affinity of the active site for substrate

Effectiveness of online social science undergraduate research experiences: Exploratory evidence

Undergraduate research experience (UREs) benefit students, but are typically conducted in person. In 2020–2021, many research and teaching activities unexpectedly moved into virtual spaces. We identify key benefits and challenges experienced by virtual URE participants in the social sciences, based on systematic coding of aligned surveys with both faculty and students. Perceived benefits included access and flexibility. Both mentors and students who had switched from in-person modalities, however, expressed a perceived loss of community, undermining the perceived effectiveness and value of the URE. They also perceived the lack of “hands-on work” as a negative. In contrast, existing online students identified UREs as creating a much needed and valued connection, enhancing their experiences. We suggest the experience of all participants in virtual UREs can benefit from centralizing community-building strategies, and give some possible examples

The effects of surface pretreatment on the cyclic-fatigue characteristics of bonded aluminium-alloy joints

Accepted versio

Dangerous work: The gendered nature of bullying in the context of higher education

This paper discusses results from a research project which set out to investigate gender differences in the nature and experience of bullying within the higher education sector. Gender differences emerged in the form and perception of bullying as well as in target response. Results also indicate that, irrespective of gender, bullies can capture and subvert organizational structures and procedures (official hierarchies, mentoring systems, probationary reviews) to further their abuse of the target and to conceal aggressive intent. These outcomes are discussed in relation to gendered assumptions behind management practices and in relation to the masculinist ethic that underpins many higher education management initiatives. Overall, results indicate that bullying cannot be divorced from gender and that such behaviour needs to be seen in a gendered context

Maternal Perception of Child Weight Among Mexicans in California and Mexico

The prevalence of childhood overweight is high in Mexican immigrant communities in the United States. Understanding mother’s perceptions of child weight in immigrants’ country of origin may help to understand this high prevalence. The goal of this study was to examine and compare mothers’ perception of weight in Mexico (MX) and in an immigrant community in California (CA). We assessed perceptions of child weight using a pictorial scale with 314 mothers of 5-year-old children in MX and 60 mothers of 5 year-old-children in CA. We compared maternal reports with children’s objectively measured weight. Using chi-square and Analysis of Variance, we investigated associations of maternal perception of and satisfaction with weight according to socio-demographic characteristics. Mothers were more likely to underestimate their children’s weight in CA than in MX. On average, CA mothers wanted their children to be smaller than they currently were and mothers in MX wanted their children to be bigger than they currently were. This differed by weight status in CA with mothers of normal weight and at-risk-for-overweight children wanting them to be bigger and mothers of overweight children wanting them to be smaller. In order for programs to be effective, mothers must be able to recognize their children as overweight and want to address it. Because underestimation of weight and a desire for a larger size is common in this population, programs to address overweight may be more effective if they focus on alternative benefits of weight control strategies, such as healthy child development

Biceps, Bitches and Borgs: Reading <i>Jarhead</i>’s Representation of the Construction of the (Masculine) Military Body

This paper explores the relationship between masculinity, the body and the military through a close reading of the film Jarhead. Drawing on a Foucauldian frame of analysis, we consider three performances of the masculine military body that form key aspects of the film’s representational economy: the disciplined body, an outcome of the processes of basic training; the gendered body, realized through deployment of metaphors of the feminine to strengthen the masculine conception of the military body; and the cyborgian body, the result of the man-machine interface which is rapidly developing in many militaries around the world, and which poses significant questions for performances of military masculinity. We conclude by suggesting that the film’s rendering of the material and discursive body reveals an unexpected tension between the expectations of military bodies and the lived experience of their labour. As well as augmenting empirical explorations of male-worker-bodies and analysing the occupation of soldier as requiring a unique kind of body work, our contribution to the body-organization literature turns upon the claim that docile military bodies are made fit for purpose, but may actually no longer have a purpose for which to be fit

Exposing the myths of household water insecurity in the global north: A critical review

Safe and secure water is a cornerstone of modern life in the global North. This article critically examines a set of prevalent myths about household water in high-income countries, with a focus on Canada and the United States. Taking a relational approach, we argue that household water insecurity is a product of institutionalized structures and power, manifests unevenly through space and time, and is reproduced in places we tend to assume are the most water-secure in the world. We first briefly introduce “modern water” and the modern infrastructural ideal, a highly influential set of ideas that have shaped household water provision and infrastructure development over the past two centuries. Against this backdrop, we consolidate evidence to disrupt a set of narratives about water in high-income countries: the notion that water access is universal, clean, affordable, trustworthy, and uniformly or equitably governed. We identify five thematic areas of future research to delineate an agenda for advancing scholarship and action—including challenges of legal and regulatory regimes, the housing-water nexus, water affordability, and water quality and contamination. Data gaps underpin the experiences of household water insecurity. Taken together, our review of water security for households in high-income countries provides a conceptual map to direct critical research in this area for the coming years