Science and Technology

The neuroprotective effects of inducing the blood-brain barrier ATP-binding cassette protein transporter P-glycoprotein (P-gp) with clotrimazole (CTZ) in both fed and fasted zebrafish (Danio rerio) against the CNS-toxicant ivermectin (IVM, 22,23-dihydro avermectin B1a + 22,23-dihydro avermectin B1b) were examined. Zebrafish were administered 2 μmol/kg IVM intraperitoneally, and various behavioural assays (swimming performance, exploratory behaviour, olfactory responses, motor coordination, and escape responses) were used to measure neurological dysfunction. IVM administration alone caused a decrease in mean swim speed (91 % of controls), maximal speed (71 %), passage rate (81 %), 90° turns (81 %), and response to food stimulus (39 %). IVM exposure also increased the percent time that fish spent immobile (45 % increase over controls) and the percent of lethargic fish (40 % increase). Fish administered 30 μmol/kg of the P-gp inducer CTZ intraperitoneally 3 d prior to IVM exposure exhibited a change in only the % time spent immobile. These data indicate that P-gp induction may be limited in protecting the zebrafish CNS from IVM over baseline. Fasted fish did not differ from fed fish in the effects of IVM on behaviour, and no differences were seen following P-gp induction with CTZ. These results suggest that this chemical defence system is not downregulated when fish are challenged with limited energy availability.

This paper discusses the effects of the learning environment on an important and unique 21st century learning outcome—that of active citizenship, in contrast to more conventionally measured cognitive and attitudinal outcomes. In our study, we utilized a learning environment instrument, the Place-Based Learning and Constructivist Environment Survey (PLACES) with an integrated environmental studies program prepared for high school students in the Canadian context. Our research used a retrospective case study design to investigate how aspects of this unique learning environment are related to long-term, active citizenship outcomes as perceived by students from two previous student cohorts (N = 24 and N = 36) who were contacted several years after the culmination of the program. To access information about student perceptions, PLACES was implemented as part of a range of mixed methods which also included focus groups and interviews. This study is important because it links key aspects of the learning environment to long-term citizenship outcomes and is unique in that the data were collected five and eight years later as part of a longitudinal study. Our findings demonstrate that the learning environment and citizenship outcomes were closely linked, and that students’ perceptions as measured by the PLACES instrument (past and present) were remarkably stable across all dimensions. These findings further indicate significant and positive implications for future learning environments research.

1. Using the two electrode voltage clamp configuration, a high voltage activated whole-cell Ca2+ channel current (IBa) was recorded from a cluster of neurosecretory ‘Light Yellow’ Cells (LYC) in the right parietal ganglion of the pond snail Lymnaea stagnalis. 2. Recordings of IBa from LYCs show a reversible concentration-dependent depression of current amplitude in the presence of the volatile anaesthetics halothane, isoflurane and sevoflurane, or the non-volatile anaesthetic pentobarbitone at clinical concentrations. 3. In the presence of the anaesthetics investigated, IBa measured at the end of the depolarizing test pulse showed proportionally greater depression than that at measured peak amplitude, as well as significant decrease in the rate of activation or increase in inactivation or both. 4. Within the range of concentrations used, the concentration-response plots for all the anaesthetics investigated correlate strongly to straight line functions, with linear regression R2 values > 0.99 in all instances. 5. For volatile anaesthetics, the dose-response regression slopes for IBa increase in magnitude, in order of gradient: sevoflurane, isoflurane and halothane, a sequence which reflects their order of clinical potency in terms of MAC value."

In the four decades straddling the turn of the nineteenth century, the small Ontario town of Niagara-on-the-Lake experienced marked growth in its tourism industry. Catering predominantly to wealthy upper-middle-class Canadian and American visitors, the lake-side settlement offered numerous opportunities for polite recreation. Chief among them was lawn tennis, a sport that sat somewhat outside of the mainstream in terms of its high-class, mixed-sex participation demographic. While its players were imbued with a strong amateur philosophy, local boosters recognized the sport’s potential to generate tourism income through its two tournaments, but this hinged on the outward presentation among its players/guests of refined gentility—a reflection of both class and gender—both on and off the court. This article considers how lawn tennis tournaments fit into the town’s burgeoning tourism industry, and examines gender relations—particularly the role of women—in relation to this development.

This article examines the connections between (lawn) tennis in Britain and the Great War (1914–1918). While previous historical research has suggested a four-year hiatus, in fact the sport continued to be played during the war, recreationally and among servicemen/women and more elite players in exhibition matches. Anecdotes about the cessation of tournaments and restricted play were interspersed with debates about the appropriateness of continuing play recreationally, as the ‘gentleman in tennis flannels’ became a symbol of public censure. Alongside enlistment, tennis players responded to the call byoffering their club facilities to the war effort, digging up courts to plant vegetables, hosting charity matches, and providing entertainment for convalescent soldiers. This analysis highlights the significance of tennis as a vehicle to promote a kind of British identity, as responses to the war as seen through tennis reflected broader sporting ideals, privileging amateurism, fair play and the ‘stuff upper lip’.

In view of scholarly work that has explored the socio-psycho significance of national performativity, the body and the “other,” this article critically analyses newspaper representations of the Canadian-born British tennis player Greg Rusedski. Drawing on Lacanian interpretations of the body, it illustrates how Rusedski’s media framing centered on a particular feature of his body – his “smile.” In doing so, we detail how Rusedski’s “post-imperial” Otherness – conceived as a form of “extimacy” (extimité) – complicated any clear delineation between “us” and “them,” positing instead a dialectical understanding of the splits, voids and contradictions that underscore the national “us.”

Sport continues to be one of the primary means through which notions of Englishness and Britishness are constructed, contested, and resisted. The legacy of the role of sport in the colonial project of the British Empire, combined with more recent connections between sport and far right fascist/nationalist politics, has made the association between Britishness, Englishness, and ethnic identity(ies) particularly intriguing. In this paper, these intersections are explored through British media coverage of the Canadian-born, British tennis player, Greg Rusedski. This coverage is examined through the lens of ‘performativity,’ as articulated by Judith Butler. Through a critical application of Butler's ideas, the ways in which the media seek to recognise and normalise certain identities, while problematising and excluding others, can be more fully appreciated. Thus, it was within newspaper framings of Rusedski that hegemonic notions of White Englishness could be performed, maintained, and embedded.

Commitment to autogamy blocks mating reactivity in Paramecium. Cells which had previously developed mating reactivity, lost reactivity 30–90 min prior to the preautogamous fission. Mating reactivity develops at a standard level of starvation when cells are allowed to exhaust their food supply naturally. In abruptly starved cultures, mating reactivity appears 3.3 h after downshift. Autogamy is also triggered by starvation. The level of starvation required for initiation of autogamy decreases progressively as cells age. When the autogamy starvation threshold drops to such a low level that all cells become committed to autogamy before any of them develop mating reactivity, reactivity does not occur under natural starvation conditions and the period of maturity for conjugation has come to an end. There is no absolute immature period for autogamy.

Nonlinear dynamics theory has been a tool of choice in the analysis of physiological signals and systems. This paper presents a novel approach in the analysis of tracheal swallowing and breath sounds based on nonlinear dynamics theory. As the tracheal sound signal is nonstationary, the signal was studied based on the recurrence quantification analysis (RQA) method, which is a useful technique in the analysis of nonstationary and noisy signals. Tracheal sound recordings of 15 healthy and 9 dysphagic subjects were studied. The multidimensional state space trajectory of each signal was reconstructed using Taken’s method of delays. The reconstructed trajectories were analyzed by the RQA technique. The preliminary results suggested that some recurrence parameters were appreciably different between swallowing and breath sounds. In order to confirm discriminating ability of the parameters, an automated method for extraction of swallowing sounds in the records of the tracheal swallowing and breath sounds was investigated. The swallowing sound extraction results were validated by manual inspection of the simultaneously recorded airflow signal and spectrogram of the sounds and also by auditory means. Experimental results proved that the investigated method more accurately detected the boundaries of swallowing sounds than methods proposed previously. Swallowing sound detection may be employed in a system for automated swallowing assessment and diagnosis of swallowing disorders (dysphagia) by acoustical means.