Cell adhesion and cortex contractility determine cell patterning in the Drosophila retina

Hayashi and Carthew (Nature 431 [2004], 647) have shown that the packing of cone cells in the Drosophila retina resembles soap bubble packing, and that changing E- and N-cadherin expression can change this packing, as well as cell shape. The analogy with bubbles suggests that cell packing is driven by surface minimization. We find that this assumption is insufficient to model the experimentally observed shapes and packing of the cells based on their cadherin expression. We then consider a model in which adhesion leads to a surface increase, balanced by cell cortex contraction. Using the experimentally observed distributions of E- and N-cadherin, we simulate the packing and cell shapes in the wildtype eye. Furthermore, by changing only the corresponding parameters, this model can describe the mutants with different numbers of cells, or changes in cadherin expression.Comment: revised manuscript; 8 pages, 6 figures; supplementary information not include

Promoting Organizational Learning in Healthcare through Simulation: A Study in Serendipity

In a case study of a simulation-based medical education program, we serendipitously discovered organizational learning as it emerged among expected patterns of individual learning. During simulation debriefings, radiologists-in-training (“residents”) spontaneously engaged in organizational learning processes. They identified routines that hindered patient care for uncommon, but potentially fatal contrast media reactions. We provide exemplars illustrating how residents identified system-related patient safety threats. Residents learned directly from simulation, recollected clinical encounters, and constructed hypothetical histories (imagining what could have happened in their hospitals). We discuss implications for organizational learning from hypothetical histories and future research promoting organizational learning in healthcare through simulation

A Quantitative Method to Analyze Drosophila Pupal Eye Patterning

BACKGROUND:The Drosophila pupal eye has become a popular paradigm for understanding morphogenesis and tissue patterning. Correct rearrangement of cells between ommatidia is required to organize the ommatidial array across the eye field. This requires cell movement, cell death, changes to cell-cell adhesion, signaling and fate specification. METHODOLOGY:We describe a method to quantitatively assess mis-patterning of the Drosophila pupal eye and objectively calculate a 'mis-patterning score' characteristic of a specific genotype. This entails step-by-step scoring of specific traits observed in pupal eyes dissected 40-42 hours after puparium formation and subsequent statistical analysis of this data. SIGNIFICANCE:This method provides an unbiased quantitative score of mis-patterning severity that can be used to compare the impact of different genetic mutations on tissue patterning

“Like, pissing yourself is not a particularly attractive quality, let’s be honest” : learning to contain through youth, adulthood, disability and sexuality

In this article, we (re)conceptualise containment in the context of youth, gender, disability, crip sex/uality and pleasure. We begin by exploring eugenic histories of containment and trace the ways in which the anomalous embodiment of disabled people (Shildrick, 2009) remains vigorously policed within current neo-eugenic discourse. Drawing upon data from two corresponding research studies, we bring the lived experiences of disabled young people to the fore. We explore their stories of performing, enacting and realising containment: containing the posited unruliness of the leaky impaired body; containment as a form of (gendered) labour (Liddiard, 2013a); containment as a marker of normalisation and sexualisation, and thus a necessary component for ableist adulthood (Slater, 2015). Thus, we theorise crip embodiment as permeable, porous and thus problematic in the context of the impossibly bound compulsory (sexually) able adult body (McRuer, 2006). We suggest that the implicit learning of containment is therefore required of disabled young people, particularly women, to counter infantilising and desexualising discourse and cross the 'border zone of youth' (Lesko, 2012) and achieve normative neoliberal adulthood. Crucially, however, we examine the meaning of what we argue are important moments of messiness: the precarious localities of leakage which disrupt containment and thus the 'reality' of the 'able' 'adult' body. We conclude by considering the ways in which these bodily ways of being contour both material experiences of pleasure and the right(s) to obtain it

School toilets : queer, disabled bodies and gendered lessons of embodiment

In this paper we argue that school toilets function as one civilising site (Elias, 1978) in which children learn that disabled and queer bodies are out of place. This paper is the first to offer queer and crip perspectives on school toilets. The small body of existing school toilet literature generally works from a normative position which implicitly perpetuates dominant and oppressive ideals. We draw on data from Around the Toilet, a collaborative research project with queer, trans and disabled people (aroundthetoilet.wordpress.com) to critically interrogate this work. In doing this we consider ‘toilet training’ as a form of ‘civilisation’, that teaches lessons around identity, embodiment and ab/normal ways of being in the world. Furthermore, we show that ‘toilet training’ continues into adulthood, albeit in ways that are less easily identifiable than in the early years. We therefore call for a more critical, inclusive, and transformative approach to school toilet research

Study on Multicellular Systems Using a Phase Field Model

A model of multicellular systems with several types of cells is developed from the phase field model. The model is presented as a set of partial differential equations of the field variables, each of which expresses the shape of one cell. The dynamics of each cell is based on the criteria for minimizing the surface area and retaining a certain volume. The effects of cell adhesion and excluded volume are also taken into account. The proposed model can be used to find the position of the membrane and/or the cortex of each cell without the need to adopt extra variables. This model is suitable for numerical simulations of a system having a large number of cells. The two-dimensional results of cell adhesion, rearrangement of a cell cluster, and chemotaxis as well as the three-dimensional results of cell clusters on the substrate are presented.Comment: 13 pages, 7 figure

Search for right-handed W bosons in top quark decay

We present a measurement of the fraction f+ of right-handed W bosons produced in top quark decays, based on a candidate sample of $t\bar{t}$ events in the lepton+jets decay mode. These data correspond to an integrated luminosity of 230pb^-1, collected by the DO detector at the Fermilab Tevatron $p\bar{p}$ Collider at sqrt(s)=1.96 TeV. We use a constrained fit to reconstruct the kinematics of the $t\bar{t}$ and decay products, which allows for the measurement of the leptonic decay angle $\theta^*$ for each event. By comparing the $\cos\theta^*$ distribution from the data with those for the expected background and signal for various values of f+, we find f+=0.00+-0.13(stat)+-0.07(syst). This measurement is consistent with the standard model prediction of f+=3.6x10^-4.Comment: Submitted to Physical Review D Rapid Communications 7 pages, 3 figure

Measurement of the Lifetime Difference in the B_s^0 System

We present a study of the decay B_s^0 -> J/psi phi We obtain the CP-odd fraction in the final state at time zero, R_perp = 0.16 +/- 0.10 (stat) +/- 0.02 (syst), the average lifetime of the (B_s, B_sbar) system, tau (B_s^0) =1.39^{+0.13}_{-0.16} (stat) ^{+0.01}_{-0.02} (syst) ps, and the relative width difference between the heavy and light mass eigenstates, Delta Gamma/Gamma = (Gamma_L - Gamma_H)/Gamma =0.24^{+0.28}_{-0.38} (stat) ^{+0.03}_{-0.04} (syst). With the additional constraint from the world average of the B_s^0$lifetime measurements using semileptonic decays, we find tau (B_s^0)= 1.39 +/- 0.06 ~ps and Delta Gamma/\Gamma = 0.25^{+0.14}_{-0.15}. For the ratio of the B_s^0 and B^0 lifetimes we obtain tau(B_s^0)/tau(B^0)} = 0.91 +/- 0.09 (stat) +/- 0.003 (syst).Comment: submitted to Phys. Rev. Lett. FERMILAB-PUB-05-324-