Environmental and biological drivers of feeding and spatial dynamics in the green sea urchin, Strongylocentrotus droebachiensis

In eastern Canada, the destruction of foundational kelp beds by dense aggregations (fronts) of the omnivorous green sea urchin, Strongylocentrotus droebachiensis, is a key determinant of the structure and dynamics of shallow reef communities. Current knowledge about factors affecting the ability of S. droebachiensis to exert top-down community control is based largely on observational studies of patterns in natural habitats, yielding fragmentary, and sometimes contradictory, results. The present research incorporated laboratory microcosm experiments and surveys of urchins in natural habitats to test the effects of abiotic (wave action, water temperature) and biotic (body size, population density) factors on: (1) individual and aggregative feeding on the winged kelp, Alaria esculenta; and (2) displacement, microhabitat use, distribution, and aggregation in food-depleted habitats. Wave action, water temperature, and body size strongly affected the ability of urchins to consume kelp: individual feeding increased with increasing body size and temperature, while aggregative feeding decreased with increasing wave action. Yet, feeding in large urchins dropped by two orders of magnitude between 12 and 18°C. Increasing wave action triggered shifts in urchin displacement, microhabitat use, distribution, and aggregation: urchins reduced displacement and abandoned flat surfaces in favour of crevices. They increasingly formed two-dimensional aggregations at densities ≥110 individuals m⁻². Collectively, results provide a foundational understanding of some of the drivers of feeding and spatial dynamics of S. droebachiensis and potential impacts on the formation of grazing fronts.

What Makes Online Grocers Work? A Case Study Analysis of Factors Contributing to Online Grocery Store Profitability

This research examined the factors contributing to the performance of online grocers prior to, and following, the 2000 dot.com collapse. The primary goals were to assess the relationship between a company’s business model(s) and its performance in the online grocery channel and to determine if there were other company and/or market related factors that could account for company performance. To assess the primary goals, a case based theory building process was utilized. A three-way cross-case analysis comprising Peapod, GroceryWorks, and Tesco examined the common profit components, the structural category (e.g., pure-play, partnership, and hybrid) profit components, and the idiosyncratic profit components related to each specific company. Based on the analysis, it was determined that online grocery store business models could be represented at three distinct, but hierarchically, related levels. The first level was termed the core model and represented the basic profit structure that all online grocers needed in order to conduct operations. The next model level was termed the structural model and represented the profit structure associated with the specific business model configuration (i.e., pure-play, partnership, hybrid). The last model level was termed the augmented model and represented the company’s business model when idiosyncratic profit components were included. In relation to the five company related factors, scalability, rate of expansion, and the automation level were potential candidates for helping to explain online grocer performance. In addition, all the market structure related factors were deemed possible candidates for helping to explain online grocer performance. The study concluded by positing an alternative hypothesis concerning the performance of online grocers. Prior to this study, the prevailing wisdom was that the business models were the primary cause of online grocer performance. However, based on the core model analysis, it was hypothesized that the customer relationship activities (i.e., advertising, promotions, and loyalty program tie-ins) were the real drivers of online grocer performance.

Abundance of organic-walled dinoflagellate cysts in surface sediments from the Atlantic sector of the Southern Ocean (Appendix 2)

Thirty-two surface sediment samples from the Southern Ocean (eastern Atlantic sector), between the Subtropical Front and the Weddell Gyre, were investigated to provide information on the distribution of modern organic-walled dinoflagellate cysts in relation to the oceanic fronts of the Antarctic Circumpolar Current (ACC). A clearly distinguishable distribution pattern was observed in relation to the water masses and fronts of the ACC. The dinoflagellate cysts of species characteristic of open oceanic environments, such as Impagidinium species, are highly abundant around the Subtropical Front, whereas south of this front, cosmopolitan species such as Nematosphaeropsis labyrinthus and the cysts of Protoceratium reticulatum characterise the transition from subtropical to subantarctic surface waters. The subantarctic surface waters are dominated by the cysts of heterotrophic dinoflagellates, such as Protoperidinium spp. and Selenopemphix antarctica. The cysts of Protoperidinium spp. form the dominant part of the assemblages around the Antarctic Polar Front, whereas S. antarctica concentrations increase further to the south. The presence of S. antarctica in sediments of the Maud Rise, a region of seasonal sea-ice cover, reflects its tolerance for low temperatures and sea-ice cover. A previously undescribed species, Cryodinium meridianum gen. nov. sp. nov., has a restricted distribution pattern between the Antarctic Polar Front and the ACC-Weddell Gyre Boundary.

Immigration in Spain: Integration with Feet of Clay?

The aim of the paper is to analyze the impact of the economic crisis on the integration of the immigrant population in Spain. The Spanish case is singular because during the years of intense immigration achieved a remarkable degree of socio-cultural integration. The paper argues that such integration it has been the result of the confluence of exceptional factors rather than the result of the policy making. From a mixed methodology approach, it shows that, during the period of expansion, two factors of the immigration contribute to their coexistence with native population: finding job and access to public services. But the economic crisis, with its impact in terms of job losses and austerity policies, expose the weaknesses of the Spanish model of integration.

Sulfate Resistance of Alkali Activated Pozzolans

The consequence of sulfate attack on geopolymer concrete, made from an alkali activated natural pozzolan (AANP) has been studied in this paper. Changes in the compressive strength, expansion and capillary water absorption of specimens have been investigated combined with phases determination by means of X-ray diffraction. At the end of present investigation which was to evaluate the performance of natural alumina silica based geopolymer concrete in sodium and magnesium sulfate solution, the loss of compressive strength and percentage of expansion of AANP concrete was recorded up to 19.4% and 0.074, respectively.

Regenerative Cues of Myeloid Cells on Pancreatic Epithelium

Thesis (Ph.D.)--University of Washington, 2016-07

Attraction and image for the Australian rail industry

Despite the global financial downturn, the Australian rail industry is in a period of expansion. Reports indicate that the industry is not attracting sufficient entry level and mid-career engineers and skilled technicians from within the Australian labour market and is facing widespread retirements from an ageing workforce. This paper reports on a completed qualitative study that explores the perceptions of engineering students, their lecturers, careers advisors and recruitment consultants regarding rail as a brand and of careers in the rail industry. Findings are presented about career knowledge, job characteristic preferences, branding and image and indicate that rail as a brand has a dated image, that young people and their influencers have little knowledge of rail careers and that rail could better focus its image and recruitment strategies. Conclusions include suggestions for more effective attraction and image strategies for the industry and for further research.

Terrain following using wide field optic flow

Wall and terrain following is a challenging problem for small, fast, and fragile robot vehicles. This paper presents a robust algorithm based on wide field integration of optic flow. Solutions for two dimensional and three dimensional wall following is provided for vehicles with non-holonomic velocity constraints that ensure that the focus of expansion of the flow field is known. The potential of the proposed algorithm is demonstrated in a simulation environment.

An expanded critical incident approach for exploring information use and learning

Critical incidents offer a focus for exploratory research about human experiences, including information use and information literacy learning. This paper describes how critical incidents underpinned research about international students’ use of online information resources at two Australian universities. It outlines the development and application of an expanded critical incident approach (ECIA), explaining how ECIA built upon critical incident technique (CIT) and incorporated information literacy theory. It discusses points of expansion (differences) between CIT and ECIA. While CIT initially proved useful in structuring the research, the pilot study revealed methodological limitations. ECIA allowed more nuanced data analysis and the integration of reflection. The study produced a multifaceted word picture of international students’ experience of using online information resources to learn, and a set of critical findings about their information literacy learning needs. ECIA offers a fresh approach for researching information use, information experience, evidence-based practice, information literacy and informed learning.

Matrix metalloproteinase localisation by in situ-RT-PCR in archival human breast biopsy material

Utilising archival human breast cancer biopsy material we examined the stromal/epithelial interactions of several matrix metalloproteinases (MMPs) using in situ-RT-PCR (IS-RT-PCR). In breast cancer, the stromal/epithelial interactions that occur, and the site of production of these proteases, are central to understanding their role in invasive and metastatic processes. We examined MT1-MMP (MMP-14, membrane type-1-MMP), MMP-1 (interstitial collagenase) and MMP-3 (stromelysin-1) for their localisation profile in progressive breast cancer biopsy material (poorly differentiated invasive breast carcinoma (PDIBC), invasive breast carcinomas (IBC) and lymph node metastases (LNM)). Expression of MT1-MMP, MMP-1 and MMP-3 was observed in both the tumour epithelial and surrounding stromal cells in most tissue sections examined. MT1-MMP expression was predominantly localised to the tumour component in the pre-invasive lesions. MMP-1 gene expression was relatively well distributed between both tissue compartments, while MMP-3 demonstrated highest expression levels in the stromal tissue surrounding the epithelial tumour cells. The results demonstrate the ability to distinguish compartmental gene expression profiles using IS-RT-PCR. Further, we suggest a role for MT1-MMP in early tumour progression, expression of MMP-1 during metastasis and focal expression pattern of MMP-3 in areas of expansion. These expression profiles may provide markers for early breast cancer diagnoses and present potential therapeutic targets.

Do pioneer cells exist?

Most mathematical models of collective cell spreading make the standard assumption that the cell diffusivity and cell proliferation rate are constants that do not vary across the cell population. Here we present a combined experimental and mathematical modeling study which aims to investigate how differences in the cell diffusivity and cell proliferation rate amongst a population of cells can impact the collective behavior of the population. We present data from a three–dimensional transwell migration assay which suggests that the cell diffusivity of some groups of cells within the population can be as much as three times higher than the cell diffusivity of other groups of cells within the population. Using this information, we explore the consequences of explicitly representing this variability in a mathematical model of a scratch assay where we treat the total population of cells as two, possibly distinct, subpopulations. Our results show that when we make the standard assumption that all cells within the population behave identically we observe the formation of moving fronts of cells where both subpopulations are well–mixed and indistinguishable. In contrast, when we consider the same system where the two subpopulations are distinct, we observe a very different outcome where the spreading population becomes spatially organized with the more motile subpopulation dominating at the leading edge while the less motile subpopulation is practically absent from the leading edge. These modeling predictions are consistent with previous experimental observations and suggest that standard mathematical approaches, where we treat the cell diffusivity and cell proliferation rate as constants, might not be appropriate.

Parallel attentive visual tracking

The research reported here addresses the problem of detecting and tracking independently moving objects from a moving observer in real-time, using corners as object tokens. Corners are detected using the Harris corner detector, and local image-plane constraints are employed to solve the correspondence problem. The approach relaxes the restrictive static-world assumption conventionally made, and is therefore capable of tracking independently moving and deformable objects. Tracking is performed without the use of any 3-dimensional motion model. The technique is novel in that, unlike traditional feature-tracking algorithms where feature detection and tracking is carried out over the entire image-plane, here it is restricted to those areas most likely to contain-meaningful image structure. Two distinct types of instantiation regions are identified, these being the “focus-of-expansion” region and “border” regions of the image-plane. The size and location of these regions are defined from a combination of odometry information and a limited knowledge of the operating scenario. The algorithms developed have been tested on real image sequences taken from typical driving scenarios. Implementation of the algorithm using T800 Transputers has shown that near-linear speedups are achievable, and that real-time operation is possible (half-video rate has been achieved using 30 processing elements).

Allergen capture by IgE and IgG enhanced cell-binding by allergen multimers: How complex is it?

Allergic diseases are the most common chronic disease of the western world, costing $7.8 billion per year in lost productivity and medical care in Australia alone.1 IgE is central to the immunopathogenesis of allergic diseases and important advances are now being made on multiple fronts of IgE research. In particular, two groups independently invested in the generation of IgE reporter mice to address the vexing question of the route of development of the elusive IgE+ B cell.2, 3 Two new anti-IgE mAb targeting membrane IgE and cell-bound IgE have the potential to deplete the cellular source of IgE.4, 5 These could be candidates for alternative anti-IgE treatment options with advantages over current anti-IgE therapy (OmalizumAb), which depletes free serum IgE. Researchers are still intrigued by the modes of interaction of IgE with allergen, and with both its receptors; the high affinity FcεR1 on mast cells and basophils, and the low affinity, C-type lectin, IgE receptor, CD23,6 on B cells and monocytes (Figure 1a and b). A new approach to the study of the complexity of these interactions was recently reported by Reginald et al.7 on page 167 of this issue.

The Eligibility Definition Used in the Social Security Administration’s Disability Programs Needs to be Changed

In its October 2003 report on the definition of disability used by the Social Security Administration’s (SSA’s) disability programs [i.e., Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) for people with disabilities], the Social Security Advisory Board raises the issue of whether this definition is at odds with the concept of disability embodied in the Americans with Disabilities Act (ADA) and, more importantly, with the aspirations of people with disabilities to be full participants in mainstream social activities and lead fulfilling, productive lives. The Board declares that “the Nation must face up to the contradictions created by the existing definition of disability.” I wholeheartedly agree. Further, I have concluded that we have to make fundamental, conceptual changes to both how we define eligibility for economic security benefits, and how we provide those benefits, if we are ever to fulfill the promise of the ADA. To convince you of that proposition, I will begin by relating a number of facts that paint a very bleak picture – a picture of deterioration in the economic security of the population that the disability programs are intended to serve; a picture of programs that purport to provide economic security, but are themselves financially insecure and subject to cycles of expansion and cuts that undermine their purpose; a picture of programs that are facing their biggest expenditure crisis ever; and a picture of an eligibility determination process that is inefficient and inequitable -- one that rations benefits by imposing high application costs on applicants in an arbitrary fashion. I will then argue that the fundamental reason for this bleak picture is the conceptual definition of eligibility that these programs use – one rooted in a disability paradigm that social scientists, people with disabilities, and, to a substantial extent, the public have rejected as being flawed, most emphatically through the passage of the ADA. Current law requires eligibility rules to be based on the premise that disability is medically determinable. That’s wrong because, as the ADA recognizes, a person’s environment matters. I will further argue that programs relying on this eligibility definition must inevitably: reward people if they do not try to help themselves, but not if they do; push the people they serve out of society’s mainstream, fostering a culture of isolation and dependency; relegate many to a lifetime of poverty; and undermine their promise of economic security because of the periodic “reforms” that are necessary to maintain taxpayer support. I conclude by pointing out that to change the conceptual definition for program eligibility, we also must change our whole approach to providing for the economic security of people with disabilities. We need to replace our current “caretaker” approach with one that emphasizes helping people with disabilities help themselves. I will briefly describe features that such a program might require, and point out the most significant challenges we would face in making the transition.

Composite scheme using localized relaxation with non-standard finite difference method for hyperbolic conservation laws

Non-standard finite difference methods (NSFDM) introduced by Mickens [Non-standard Finite Difference Models of Differential Equations, World Scientific, Singapore, 1994] are interesting alternatives to the traditional finite difference and finite volume methods. When applied to linear hyperbolic conservation laws, these methods reproduce exact solutions. In this paper, the NSFDM is first extended to hyperbolic systems of conservation laws, by a novel utilization of the decoupled equations using characteristic variables. In the second part of this paper, the NSFDM is studied for its efficacy in application to nonlinear scalar hyperbolic conservation laws. The original NSFDMs introduced by Mickens (1994) were not in conservation form, which is an important feature in capturing discontinuities at the right locations. Mickens [Construction and analysis of a non-standard finite difference scheme for the Burgers–Fisher equations, Journal of Sound and Vibration 257 (4) (2002) 791–797] recently introduced a NSFDM in conservative form. This method captures the shock waves exactly, without any numerical dissipation. In this paper, this algorithm is tested for the case of expansion waves with sonic points and is found to generate unphysical expansion shocks. As a remedy to this defect, we use the strategy of composite schemes [R. Liska, B. Wendroff, Composite schemes for conservation laws, SIAM Journal of Numerical Analysis 35 (6) (1998) 2250–2271] in which the accurate NSFDM is used as the basic scheme and localized relaxation NSFDM is used as the supporting scheme which acts like a filter. Relaxation schemes introduced by Jin and Xin [The relaxation schemes for systems of conservation laws in arbitrary space dimensions, Communications in Pure and Applied Mathematics 48 (1995) 235–276] are based on relaxation systems which replace the nonlinear hyperbolic conservation laws by a semi-linear system with a stiff relaxation term. The relaxation parameter (λ) is chosen locally on the three point stencil of grid which makes the proposed method more efficient. This composite scheme overcomes the problem of unphysical expansion shocks and captures the shock waves with an accuracy better than the upwind relaxation scheme, as demonstrated by the test cases, together with comparisons with popular numerical methods like Roe scheme and ENO schemes.