Haematopoietic differentiation of murine embryonic stem cells

Haematopoietic stem cells (HSCs) are routinely used to treat haematological disorders, as they can engraft into the bone marrow of immuno-compromised recipients where they undergo self-renewal and multilineage differentiation to provide long-term reconstitution of the blood system. Identification of novel factors able to regulate or expand HSCs would have a significant impact in a clinical setting. Mouse embryonic stem (ES) cells can be used as a model system to investigate haematopoietic regulation, since these pluripotent cells are amenable to large-scale culture and have the capacity to differentiate into a variety of cell types in vitro, including cells of haematopoietic lineages. Mature blood cells can be generated relatively easily from ES cells; however, HSCs are generated at relatively low frequencies and there has been only limited success in the contribution of these cells to the adult haematopoietic system in vivo. Previous work demonstrated that the frequency of haematopoietic progenitors was significantly increased when ES cells were co-cultured with primary El0.5 aorta-gonad-mesonephros (AGM) tissue explants, a region which is able to give rise to HSCs in vivo. Therefore, the AGM region is a potent source of haematopoietic inductive signals both in vivo and for ES cells in vitro.This project aimed to determine which subregion(s) of the AGM were responsible for the haematopoietic enhancing effects that primary AGM explants had on differentiating ES cells. To this end, a novel co-culture system has been established to test the enhancing effects of a panel of clonal stromal cell lines derived from different subregions of the midgestational AGM. It was found that three clonal stromal cell lines derived from the dorsal aorta and surrounding mesenchyme (AM) subregion of the AGM were able to significantly enhance the frequency of ES cell derived multipotent haematopoietic progenitors, as measured by in vitro colony assays and flow cytometry. By contrast, two stromal cell lines derived from the urogenital ridges (UG) of the AGM did not enhance haematopoietic differentiation of ES cells. Interestingly, the enhancing capacity of the AM-derived stroma was comparable with that of the bone marrow derived OP9 stromal cell line, which has been widely used in the literature to promote haematopoietic differentiation of ES cells. Further investigation revealed that the enhancing capacity is not retained by extracellular matrices isolated from the AM stromal cell layers and the effects were dependent on direct ES cell-stromal cell contact. Co-culture of an ES cell line carrying a mesoderm specific Brachyury-eGFP reporter gene demonstrated that the stromal lines mediated their effects post- Brachyury (mesoderm) induction in the ES cells. In addition, co-culture of sorted ES cell populations confirmed that Brachyury*, but not Brachyury', cells gave rise to haematopoietic progenitors in AM stromal co-culture, supporting the notion that ES cell differentiation recapitulated the in vivo pattern of lineage specification. Transplantation of co-cultured ES cells into irradiated adult NOD/SCID mouse recipients led to low levels of donor cell engraftment in the spleen and bone marrow, which expanded upon serial transplantation; but full repopulation of the recipient haematopoietic system was not confirmed. Adult bone marrow cells were found to achieve repopulation more readily in the NOD/SCID animal model when transplanted intra-splenically, as compared to intra-venous injection. This suggests that transplantation of ES-derived haematopoietic cells directly into the haematopoietic niche, by intra-splenic or intrafemoral injection, could facilitate repopulation

Zeno and anti-Zeno effects for quantum Brownian motion

In this paper we investigate the occurrence of the Zeno and anti-Zeno effects for quantum Brownian motion. We single out the parameters of both the system and the reservoir governing the crossover between Zeno and anti-Zeno dynamics. We demonstrate that, for high reservoir temperatures, the short time behaviour of environment induced decoherence is the ultimate responsible for the occurrence of either the Zeno or the anti-Zeno effect. Finally we suggest a way to manipulate the decay rate of the system and to observe a controlled continuous passage from decay suppression to decay acceleration using engineered reservoirs in the trapped ion context .Comment: 4 pages, 1 figure. v2: Replaced with the published version. Minor modifications in the text and titl

Service user reflections on the impact of involvement in research

Background : Reports about the impact of patient and public involvement in research can be improved by involving patients and research staff more collaboratively to co-produce instruments to measure their involvement. This commentary, written by two members of a hospital-based patient panel and their coordinator for its work, describes how we co-produced instruments to evaluate the impact and effectiveness of our involvement. We present here the results, including our quantitative and qualitative findings, of this patient led evaluation and reflect on how our involvement has made a difference to the research projects and research infrastructure within the hospital in which we operate and on us as a panel. Methods : Existing impact frameworks and guidelines were reviewed. Members co-produced and piloted qualitative questionnaires to identify values associated with patient and public involvement (PPI) from both a researcher and panel member perspective, and collected quantitative metrics to provide descriptive statistics on the type of involvement and activities. Members also produced a comments slip to provide contemporaneous feedback after each meeting. Results : The panel has reviewed 36 research projects for the Therapeutics and Palliative Care Directorate drawn from speech and language therapy, physiotherapy, occupational therapy, dietetics, podiatry, palliative care services and chaplaincy. Some of the main results of our involvement have been the development of grant applications and making written information more understandable for research participants. Examples of how the Panel made a difference included providing an effective forum for debate by providing practical suggestions to improve research design and identifying potential issues that may not have occurred to the researcher. The panel has had an impact outside of meetings both within the context in which it operates and on the individuals involved. Examples included: influencing the Directorate research agenda, sharing resources with other groups, developing research relationships, and enabling member participation in different roles and settings. Discussion : Embedding ourselves within the Directorate research infrastructure has enabled us to adapt to organisational change and actively contribute to the research strategy. There is greater scope for involvement in areas of cost effectiveness and economic evaluation. Increasing member contributions and networking with other groups provides added value as well as cross fertilisation of ideas as part of our widening impact. Conclusion : Evaluating the impact of our involvement has improved our understanding of what aspects of involvement work best for the panel and the researchers who attend our meetings, and in the different settings that we work in. It has helped us to focus on how we need to develop to maximise our resources going forward

A History of Supra-Arcade Downflows and Their Connection to Reconnection

No abstract availabl

An interpretable artificial intelligence based smart agriculture system

With increasing world population the demand of food production has increased exponentially. Internet of Things (IoT) based smart agriculture system can play a vital role in optimising crop yield by managing crop requirements in real-time. Interpretability can be an important factor to make such systems trusted and easily adopted by farmers. In this paper, we propose a novel artificial intelligence-based agriculture system that uses IoT data to monitor the environment and alerts farmers to take the required actions for maintaining ideal conditions for crop production. The strength of the proposed system is in its interpretability which makes it easy for farmers to understand, trust and use it. The use of fuzzy logic makes the system customisable in terms of types/number of sensors, type of crop, and adaptable for any soil types and weather conditions. The proposed system can identify anomalous data due to security breaches or hardware malfunction using machine learning algorithms. To ensure the viability of the system we have conducted thorough research related to agricultural factors such as soil type, soil moisture, soil temperature, plant life cycle, irrigation requirement and water application timing for Maize as our target crop. The experimental results show that our proposed system is interpretable, can detect anomalous data, and triggers actions accurately based on crop requirements

Current Sheet and Reconnection Inflow-Outflow Observations During Solar Eruptions

Magnetic reconnection is widely accepted as a dominant source of energy during solar flares; however, observations of it have been indirect and/or incomplete. Using the suite of instruments available spanning wavelength space, we will provide observations and measurements of both the inputs and outputs predicted from reconnection in the form of inflows preceding outflows (i.e. supra-arcade downflows, supra-arcade downflowing loops, upflows, and disconnection events). We will also present evidence for current sheets through which reconnection is expected to occur and discuss current sheet motion during flare progression

Observations of a Two-Stage Solar Eruptive Event (SEE): Evidence for Secondary Heating

We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event (SEE) that occurred at the South-West limb on 8 March, 2011. The GOES X-ray light curve shows two peaks separated by almost two hours that we interpret as two stages of a single event associated with the delayed eruption of a CME. A hot flux rope formed during the first stage and continued expanding and rising throughout the event. The speed of the flux rope decreased from approx.120 to 14 km/s during the decay phase of the first stage and increased again during the second stage to become the CME with a speed of approx.516 km/s. RHESSI and GOES data analyses show that the plasma temperature reached over 20 MK in the first stage, then decreased to approx.10 MK and increased to 15 MK in the second stage. This event provides clear evidence for a secondary heating phase. The enhanced EUV and X-ray emission came from the high corona ( approx.60 arcsec above the limb) in the second stage, approx.40 arcsec higher than the site of the initial flare emission. STEREO-A on-disk observations indicate that the post-flare loops during this stage were of larger scale sizes and spatially distinct from those in the first stage

Mouse extraembryonic arterial vessels harbor precursors capable of maturing into definitive HSCs

During mouse development, definitive hematopoietic stem cells (dHSCs) emerge by late E10.5 to E11 in several hematopoietic sites. Of them, the aorta-gonad-mesonephros (AGM) region drew particular attention owing to its capacity to autonomously initiate and expand dHSCs in culture, indicating its key role in HSC development. The dorsal aorta contains characteristic hematopoietic clusters and is the initial site of dHSC emergence, where they mature through vascular endothelial (VE)-cadherin(+)CD45(–)CD41(low) (type 1 pre-HSCs) and VE-cadherin(+)CD45(+) (type 2 pre-HSCs) intermediates. Although dHSCs were also found in other embryonic niches (placenta, yolk sac, and extraembryonic vessels), attempts to detect their HSC initiating potential have been unsuccessful to date. Extraembryonic arterial vessels contain hematopoietic clusters, suggesting that they develop HSCs, but functional evidence for this has been lacking. Here we show that umbilical cord and vitelline arteries (VAs), but not veins, contain pre-HSCs capable of maturing into dHSCs in the presence of exogenous interleukin 3, although in fewer numbers than the AGM region, and that pre-HSC activity in VAs increases with proximity to the embryo proper. Our functional data strongly suggest that extraembryonic arteries can actively contribute to adult hematopoiesis

The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN

SDSS J015957.64+003310.5 is an X-ray selected, $z=0.31$ AGN from the Stripe 82X survey that transitioned from a Type 1 quasar to a Type 1.9 AGN between 2000 and 2010. This is the most distant AGN, and first quasar, yet observed to have undergone such a dramatic change. We re-observed the source with the double spectrograph on the Palomar 5m telescope in July 2014 and found that the spectrum is unchanged since 2010. From fitting the optical spectra, we find that the AGN flux dropped by a factor of 6 between 2000 and 2010 while the broad H$\alpha$ emission faded and broadened. Serendipitous X-ray observations caught the source in both the bright and dim state, showing a similar 2-10 keV flux diminution as the optical while lacking signatures of obscuration. The optical and X-ray changes coincide with $g$-band magnitude variations over multiple epochs of Stripe 82 observations. We demonstrate that variable absorption, as might be expected from the simplest AGN unification paradigm, does not explain the observed photometric or spectral properties. We interpret the changing state of J0159+0033 to be caused by dimming of the AGN continuum, reducing the supply of ionizing photons available to excite gas in the immediate vicinity around the black hole. J0159+0033 provides insight into the intermittency of black hole growth in quasars, as well as an unprecedented opportunity to study quasar physics (in the bright state) and the host galaxy (in the dim state), which has been impossible to do in a single sources until now.Comment: accepted for publication in Ap