Multiplicity of viral infection in brown algae

Brown algae are important primary producers and habitat formers in coastal environments and are believed to have evolved multicellularity independently of the other eukaryotes. The phaeoviruses that infect them form a stable lysogenic relationship with their host via genome integration, but have only been extensively studied in two genera: Ectocarpus and Feldmannia. In this study I aim to improve our understanding of the genetic diversity, host range and distribution of phaeoviruses. Sequencing and phylogenetic analysis of amplified fragments of three core phaeoviral genes (encoding major capsid protein (MCP), DNA polymerase and superfamily III helicase) of phaeovirus infected algae confirmed the suspected phaeoviral identity of viruses infecting E. fasciculatus, F. simplex, Pilayella littoralis, Myriotrichia clavaeformis and Hincksia hincksiae. Furthermore, this approach revealed multiple virus sequence variants within individual strains, and moreover that the variants formed two distinct subgroups. Subgroup A was highly conserved and observed in multiple algal genera, whereas subgroup B was much more diverse, but only found in Feldmannia species. Transcriptome sequencing of an actively infected F. irregularis strain revealed polymorphisms within key viral genes, suggesting that multiple variants were indeed active within this strain. High resolution melt curve (HRM) technology was used to develop a high throughput screening method for detecting phaeoviral MCP as a proxy for detection of phaeoviruses. This technique was also able to assign 88% of those detected to one of the subgroups, based on their differing melting temperature distributions. This was then applied to 1034 Ectocarpus isolates collected from around Europe and South America, and in accordance with previous studies of phaeoviral infection, 43-79% of strains contain virus sequence (depending on species). 17% of the isolates tested even contained sequence from both subgroups. 82 Laminariales strains, close relatives of the Ectocarpales, were also screened because they comprise commercially important kelp species but are not known to be infected by viruses. 10-17% of these tested positive for phaeoviral MCP, which when sequenced formed a separate group within the phaeoviruses. This finding could have a major impact on the kelp farming industry if the viruses are found to affect reproduction as happens in the Ectocarpales. The discovery of two subgroups is contrary to current beliefs that the phaeoviruses are a single monophyletic group, and that each species of alga has its own phaeovirus, casting doubt on the usefulness of the current convention of naming each phaeovirus after its host. It appears that the subgroup B viruses have begun to evolve away from the stable, K-selected subgroup A viruses towards a more r- type strategy with higher mutation and diversification. This study has identified potential mechanisms that may influence this shift, including mutations in a region of the DNA polymerase known to negatively affect DNA replication fidelity, combined with an active integrase and lack of a proofreading exonuclease, along with the observed infection of individuals with both phaeovirusal subgroups. The resulting mutations and recombinations could lead to the diversity observed here, and may provide a suitable model for the study of other emergent virus infections.INTERREG (Marinexus project

More than Just a Teacher”: Anticipatory Advocacy as Vision and Defense in Urban High-need Schools

Specialized teacher preparation programs are graduating teachers with commitments to advocacy. This expanded definition of teaching stands in opposition to traditional expectations for the role of teachers that have developed during the history of U.S. education into organizational and social frames that reinforce tradition and work against reform. These influences constitute forces of professional weathering that may wear down teachers’ visions and actions for their work. This multicase study focused on four graduates from an intensive two-year teacher preparation program that included initial certification along with induction support in the second year of the program as they completed master’s degree requirements. The inquiry sought to understand how they envisioned their roles as teacher advocates and how they enacted and sustained their visions, resisting traditional teacher roles. Participants were graduates of the same cohort of the preparation program who were completing their second year of teaching in urban high-need schools and who had been nominated and confirmed as effective teachers of diverse students by faculty members of the university program and of local schools. Program materials were analyzed as background material to establish context. Primary data that were inductively and iteratively analyzed included extant course assignments, three individual interviews with each participant, three school-related observations, and three focus group interviews. Findings provide insight into the ways in which the teachers enacted a vision of anticipatory advocacy. Anticpatory advocacy includes intervening actions that are the result of a dual awareness of students’ immediate and future needs and have implications beyond boundaries of time and space in an effort to positively influence students’ lives in the immediate as well as distant future. The teachers, each of whom held beliefs that aligned with the culturally relevant foundations of the program prior to their selection, employed tools related to responsive classroom management, ambitious teaching strategies, and professional collaboration that they acquired and honed during their program. By working backward from the classrooms of effective teachers, the study links classroom practices with teacher preparation, providing direction for stakeholders concerned with the development and retention of high quality teachers for all children, especially in challenging school contexts

Relative timing based verification of timed circuits and systems

Journal ArticleAggressive timed circuits, including synchronous and asynchronous self-resetting circuits, are particularly challenging to design and verify due to complicated timing constraints that must hold to ensure correct operation. Identifying a small, sufficient, and easily verifiable set of relative timing constraints simplifies both design and verification. However, the manual identification of these constraints is a complex and error-prone process. This paper presents the first systematic algorithm to generate and optimize relative timing constraints sufficient to guarantee correctness. The algorithm has been implemented in our RTCG tool and has been applied to several real-life circuits. In all cases, the tool successfully generates a sufficient set of easily verifiable relative timing constraints. Moreover, the generated constraint sets are the same size or smaller than that of the hand-optimized constraints

Developing a Community Service-Learning Project: Sustainability in the Apparel Industry

This study is aimed at developing, implementing, and assessing a service-learning project in an apparel design and merchandising program that enhances students’ learning outcomes, fosters agency in participants, and serves the community partner. The goals of the study were twofold: first, to create and implement a service-learning project, and second, to apply Carver’s Conceptual Framework for Experiential Education to assess the success of students’ learning outcomes after the implementation of the developed project and provide a framework for educators looking to incorporate service-learning projects into their curricula (Carver, 1997)

Lattice gas cellular automata model for rippling and aggregation in myxobacteria

A lattice-gas cellular automaton (LGCA) model is used to simulate rippling and aggregation in myxobacteria. An efficient way of representing cells of different cell size, shape and orientation is presented that may be easily extended to model later stages of fruiting body formation. This LGCA model is designed to investigate whether a refractory period, a minimum response time, a maximum oscillation period and non-linear dependence of reversals of cells on C-factor are necessary assumptions for rippling. It is shown that a refractory period of 2-3 minutes, a minimum response time of up to 1 minute and no maximum oscillation period best reproduce rippling in the experiments of {\it Myxoccoccus xanthus}. Non-linear dependence of reversals on C-factor is critical at high cell density. Quantitative simulations demonstrate that the increase in wavelength of ripples when a culture is diluted with non-signaling cells can be explained entirely by the decreased density of C-signaling cells. This result further supports the hypothesis that levels of C-signaling quantitatively depend on and modulate cell density. Analysis of the interpenetrating high density waves shows the presence of a phase shift analogous to the phase shift of interpenetrating solitons. Finally, a model for swarming, aggregation and early fruiting body formation is presented

Single-photon detection timing jitter in a visible light photon counter

Visible light photon counters (VLPCs) offer many attractive features as photon detectors, such as high quantum efficiency and photon number resolution. We report measurements of the single-photon timing jitter in a VLPC, a critical performance factor in a time-correlated single-photon counting measurement, in a fiber-coupled closed-cycle cryocooler. The measured timing jitter is 240 ps full-width-at-half-maximum at a wavelength of 550 nm, with a dark count rate of 25 000 counts per second. The timing jitter increases modestly at longer wavelengths to 300 ps at 1000 nm, and increases substantially at lower bias voltages as the quantum efficiency is reduced

The supercuspidal representations of p-adic classical groups

Let G be a unitary, symplectic or special orthogonal group over a locally compact non-archimedean local field of odd residual characteristic. We construct many new supercuspidal representations of G, and Bushnell-Kutzko types for these representations. Moreover, we prove that every irreducible supercuspidal representation of G arises from our constructions.Comment: 55 pages -- minor changes from 1st version (mostly in sections 2.2, 4.2 and 6.2). To appear in Inventiones mathematicae, 2008 (DOI is not yet active as at 12 Nov 2007

Long-Term Memory for Contemporary Dance is Distributed and Collaborative

Professional dancers appear to be the embodied records of works of choreography that have been created, rehearsed and performed. Their precision in recalling extended sequences of movement developed for these works defies the conventional methods used to investigate memory. A distributed cognition view holds that memory will not only be individualistic but also extended across a dance ensemble. Working closely with the highly skilled dancers of Australian Dance Theatre (ADT), we set out to develop an ecologically valid method that elicited memory recall and lapsing. Dancers were divided into two “teams” with each team asked to choose excerpts for memory recall from the company’s extensive repertoire that would challenge individual dancers in the other team. There were 14 trials; 12 involved the dancers recalling dance excerpts on their own (solo condition) and 2 with a partner (duet condition). In the ADT studio, seven dancers recalled (reproduced) as much of the excerpt as possible in the absence of an accompanying soundscape. Recall was extensive, but contained lapses, and these recall failures form the core of the analysis in this study. Four novel types of successful memory recall were identified: static shapes, isolated movements, partial and full movement sequences; and two strategies for recall: looking for movement by moving and collaborative sketching. Four types of errors were observed: errors of detail, order, omission, and additions. Analysis was conducted through a new method of counting ‘choreographic items’. The most detailed recall (73-96%) was for the two duet excerpts with significantly poorer recall of excerpts from complex group sections of a dance. Movement gist was generally retained. The types of recall and types of errors observed pointed to the use of not only procedural memory and chaining but also contextual cues as aids to movement recall. Collaborative elements of recall were observed that suggest the importance of distributed cognition and collective memory within a contemporary dance ensemble

Unicity of types for supercuspidal representations of p-adic SL2

We consider the question of unicity of types on maximal compact subgroups for supercuspidal representations of SL2 over a nonarchimedean local field of odd residual characteristic. We introduce the notion of an archetype as the SL2-conjugacy class of a typical representation of a maximal compact subgroup, and go on to show that any archetype in SL2 is restricted from one in GL2. From this it follows that any archetype must be induced from a Bushnell-Kutzko type. Given a supercuspidal representation π of SL2(F), we give an additional explicit description of the number of archetypes admitted by π in terms of its ramification. We also describe a relationship between archetypes for GL2 and SL2 in terms of L-packets, and deduce an inertial Langlands correspondence for SL2

Dynamic range of hypercubic stochastic excitable media

We study the response properties of d-dimensional hypercubic excitable networks to a stochastic stimulus. Each site, modelled either by a three-state stochastic susceptible-infected-recovered-susceptible system or by the probabilistic Greenberg-Hastings cellular automaton, is continuously and independently stimulated by an external Poisson rate h. The response function (mean density of active sites rho versus h) is obtained via simulations (for d=1, 2, 3, 4) and mean field approximations at the single-site and pair levels (for all d). In any dimension, the dynamic range of the response function is maximized precisely at the nonequilibrium phase transition to self-sustained activity, in agreement with a reasoning recently proposed. Moreover, the maximum dynamic range attained at a given dimension d is a decreasing function of d.Comment: 7 pages, 4 figure