Modeling Stem/Progenitor Cell-Induced Neovascularization and\ud Oxygenation around Solid Implants

Tissue engineering constructs and other solid implants with biomedical applications, such as drug delivery devices or bioartificial organs, need oxygen (O2) to function properly. To understand better the vascular integration of such devices, we recently developed a novel model sensor containing O2-sensitive crystals, consisting of a polymeric capsule limited by a nano-porous filter. The sensor was implanted in mice with hydrogel alone (control) or hydrogel embedded with mouse CD117/c-kit+ bone marrow progenitor cells (BMPC) in order to stimulate peri-implant neovascularization. The sensor provided local partial O2 pressure (pO2) using non-invasive electron paramagnetic resonance (EPR) signal measurements. A consistently higher level of per-implant oxygenation was observed in the cell-treatment case as compared to the control over a 10-week period. In order to provide a mechanistic explanation of these experimental observations, we present in this paper a mathematical model, formulated as a system of coupled partial differential equations, that simulates peri-implant vascularization. In the control case, vascularization is considered to be the result of a Foreign Body Reaction (FBR) while in the cell-treatment case, adipogenesis in response to paracrine stimuli produced by the stem cells is assumed to induce neovascularization. The model is validated by fitting numerical predictions of local pO2 to measurements from the implanted sensor. The model is then used to investigate further the potential for using stem cell treatment to enhance the vascular integration of biomedical implants. We thus demonstrate how mathematical modeling combined with experimentation can be used to infer how vasculature develops around biomedical implants in control and stem celltreated cases

B Cells Activated in Lymph Nodes in Response to Ultraviolet Irradiation or by Interleukin-10 Inhibit Dendritic Cell Induction of Immunity

Ultraviolet (UV) radiation suppresses systemic immunity. We explored these cellular mechanisms by exposing mice to systemically immunosuppressive doses of UV radiation and then analyzing cell phenotype and function in the lymphoid organs. Although UV radiation increased total cell number in the draining lymph nodes (DLN), it did not alter the activation state of dendritic cells (DC). Rather, UV radiation selectively activated lymph node B cells, with these cells being larger and expressing higher levels of both anti-major histocompatibility complex II and B220 but not co-stimulatory molecules. This phenotype resembled that of a B cell geared toward immune tolerance. To test whether UV radiation-activated B cells were responsible for immunosuppression, DC and B cells were conjugated to antigen ex vivo and transferred into naïve hosts. Although DC by themselves activated T cells, when the B cells from UV radiation-irradiated mice were co-injected with DC, they suppressed DC activation of immunity. Interleukin (IL)-10-activated B cells also suppressed DC induction of immunity, suggesting that IL-10 may be involved in this suppressive effect of UV radiation. These results demonstrate a new mechanism of UV radiation immunosuppression whereby UV radiation activates B cells in the skin-DLN that can suppress DC activation of T cell-mediated immunity

The FHD/ε\boldsymbol{\varepsilon}ppsilon Epoch of Reionization Power Spectrum Pipeline

Epoch of Reionization data analysis requires unprecedented levels of accuracy in radio interferometer pipelines. We have developed an imaging power spectrum analysis to meet these requirements and generate robust 21 cm EoR measurements. In this work, we build a signal path framework to mathematically describe each step in the analysis, from data reduction in the FHD package to power spectrum generation in the $\varepsilon$ppsilon package. In particular, we focus on the distinguishing characteristics of FHD/$\varepsilon$ppsilon: highly accurate spectral calibration, extensive data verification products, and end-to-end error propagation. We present our key data analysis products in detail to facilitate understanding of the prominent systematics in image-based power spectrum analyses. As a verification to our analysis, we also highlight a full-pipeline analysis simulation to demonstrate signal preservation and lack of signal loss. This careful treatment ensures that the FHD/$\varepsilon$ppsilon power spectrum pipeline can reduce radio interferometric data to produce credible 21 cm EoR measurements.Comment: 21 pages, 10 figures, accepted by PAS

Mesoscale atmosphere ocean coupling enhances the transfer of wind energy into the ocean

Although it is well established that the large-scale wind drives much of the world’s ocean circulation, the contribution of the wind energy input at mesoscales (10–200 km) remains poorly known. Here we use regional simulations with a coupled high-resolution atmosphere–ocean model of the South Atlantic, to show that mesoscale ocean features and, in particular, eddies can be energized by their thermodynamic interactions with the atmosphere. Owing to their sea-surface temperature anomalies affecting the wind field above them, the oceanic eddies in the presence of a large-scale wind gradient provide a mesoscale conduit for the transfer of energy into the ocean. Our simulations show that this pathway is responsible for up to 10% of the kinetic energy of the oceanic mesoscale eddy field in the South Atlantic. The conditions for this pathway to inject energy directly into the mesoscale prevail over much of the Southern Ocean north of the Polar Front

A Progressive Approach to Content Generation

Abstract. PCG approaches are commonly categorised as constructive, generate-and-test or search-based. Each of these approaches has its distinctive advantages and drawbacks. In this paper, we propose an approach to Content Generation (CG) – in particular level generation – that combines the advantages of construc-tive and search-based approaches thus providing a fast, flexible and reliable way of generating diverse content of high quality. In our framework, CG is seen from a new perspective which differentiates between two main aspects of the game-play experience, namely the order of the in-game interactions and the associated level design. The framework first generates timelines following the search-based paradigm. Timelines are game-independent and they reflect the rhythmic feel of the levels. A progressive, constructive-based approach is then implemented to evaluate timelines by mapping them into level designs. The framework is applied for the generation of puzzles for the Cut the Rope game and the results in terms of performance, expressivity and controllability are characterised and discussed.

Integration of speech and gesture in aphasia

BACKGROUND: Information from speech and gesture is often integrated to comprehend a message. This integration process requires the appropriate allocation of cognitive resources to both the gesture and speech modalities. People with aphasia are likely to find integration of gesture and speech difficult. This is due to a reduction in cognitive resources, a difficulty with resource allocation or a combination of the two. Despite it being likely that people who have aphasia will have difficulty with integration, empirical evidence describing this difficulty is limited. Such a difficulty was found in a single case study by Cocks et al. in 2009, and is replicated here with a greater number of participants. AIMS: To determine whether individuals with aphasia have difficulties understanding messages in which they have to integrate speech and gesture. METHODS & PROCEDURES: Thirty-one participants with aphasia (PWA) and 30 control participants watched videos of an actor communicating a message in three different conditions: verbal only, gesture only, and verbal and gesture message combined. The message related to an action in which the name of the action (e.g., 'eat') was provided verbally and the manner of the action (e.g., hands in a position as though eating a burger) was provided gesturally. Participants then selected a picture that 'best matched' the message conveyed from a choice of four pictures which represented a gesture match only (G match), a verbal match only (V match), an integrated verbal-gesture match (Target) and an unrelated foil (UR). To determine the gain that participants obtained from integrating gesture and speech, a measure of multimodal gain (MMG) was calculated. OUTCOMES & RESULTS: The PWA were less able to integrate gesture and speech than the control participants and had significantly lower MMG scores. When the PWA had difficulty integrating, they more frequently selected the verbal match. CONCLUSIONS & IMPLICATIONS: The findings suggest that people with aphasia can have difficulty integrating speech and gesture in order to obtain meaning. Therefore, when encouraging communication partners to use gesture alongside language when communicating with people with aphasia, education regarding the types of gestures that would facilitate understanding is recommended

The thermal tolerance of crown-of-thorns (Acanthaster planci) embryos and bipinnaria larvae: implications for spatial and temporal variation in adult populations

To understand the role of sea temperature on the population biology of the crown-of-thorns sea star Acanthaster planci, the thermal window for embryonic and larval development was investigated. In two experiments, the response of embryos and larvae across 12 temperatures from 19.4 to 36.5 °C was quantified as the percentage of individuals reaching cleavage stage embryos, blastula, gastrula, early-bipinnaria, late-bipinnaria larvae or abnormal. Measurements were made at 7 times up to 72 h post-fertilisation, with the morphometrics of larvae measured in the 72-h sample. Acanthaster planci developed at temperatures between 19.4 and 33.2 °C, with a thermal window for development to the late-bipinnaria stage between 25.6 and 31.6 °C. Development rate, normal development and larval size were optimal at 28.7 °C, with development rates remaining relatively constant up to 31.6 °C. Rates of abnormality increased steadily (early embryonic stages) above 28.7 °C and was 100 % at temperatures approaching 33 °C. These experiments provide a more detailed insight into the response of A. planci developmental stages to temperature. The present day distribution of the species in eastern Australia overlap with the optimal thermal window for development to the late-bipinnaria stage (≈25–32 °C), implying a role of temperature in controlling population distributions and abundances. Despite this, short- or long-term temperature increases may not be a major modulator of the crown-of-thorns recruitment success, population dynamics and distribution in the future as no significant change in development rates, larval survival and growth occurred within this thermal window. Therefore, moderate (1–2 °C) increases in sea temperatures caused by El Nino or near-future ocean warming may not drive an increase in developmental and settlement success. Indeed, without any acclimation to warmer temperatures expected under near-future warming (+2 to 4 °C), climate change could ultimately reduce larval survival due to elevated mortality above the optimal development temperature

The Chromospheric Activity and Ages of M Dwarf Stars in Wide Binary Systems

We investigate the relationship between age and chromospheric activity for 139 M dwarf stars in wide binary systems with white dwarf companions. The age of each system is determined from the cooling age of its white dwarf component. The current limit for activity-age relations found for M dwarfs in open clusters is 4 Gyr. Our unique approach to finding ages for M stars allows for the exploration of this relationship at ages older than 4 Gyr. The general trend of stars remaining active for a longer time at later spectral type is confirmed. However, our larger sample and greater age range reveals additional complexity in assigning age based on activity alone. We find that M dwarfs in wide binaries older than 4 Gyr depart from the log-linear relation for clusters and are found to have activity at magnitudes, colors and masses which are brighter, bluer and more massive than predicted by the cluster relation. In addition to our activity-age results, we present the measured radial velocities and complete space motions for 161 white dwarf stars in wide binaries.Comment: 22 pages including 9 figures and 5 tables. Accepted for publication in The Astronomical Journa

The case for surgical skills centres in Sub Saharan Africa: The benefits and the challenges.

The purpose of this paper is to describe the educational and practice utilities of establishing Surgical Skills Centres. The paper also defines significant obstacles to the establishment of such centres in Sub- Saharan Africa. In 1996, the Royal College of Physicians and Surgeons Canada responded to the evolving roles and obligations of medical specialists by implementing a framework of core competencies called the “CanMEDS Roles” which define surgeons as medical experts, communicators, collaborators, managers, health advocates, scholars and professionals. A key competency expected of the medical expert is the demonstration of proficiency in procedural skills2

Phase transitions in social sciences: two-populations mean field theory

A new mean field statistical mechanics model of two interacting groups of spins is introduced and the phase transition studied in terms of their relative size. A jump of the average magnetization is found for large values of the mutual interaction when the relative percentage of the two populations crosses a critical threshold. It is shown how the critical percentage depends on internal interactions and on the initial magnetizations. The model is interpreted as a prototype of resident-immigrant cultural interaction and conclusions from the social sciences perspectives are drawn