266 research outputs found

    Observations of Particle Loss due to Injection-Associated Electromagnetic Ion Cyclotron Waves

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    We report on observations of electromagnetic ion cyclotron (EMIC) waves and their interactions with injected ring current particles and high energy radiation belt electrons. The magnetic field experiment aboard the twin Van Allen Probes spacecraft measured EMIC waves near L = 5.5–6. Particle data from the spacecraft show that the waves were associated with particle injections. The wave activity was also observed by a ground-based magnetometer near the spacecraft geomagnetic footprint over a more extensive temporal range. Phase space density profiles, calculated from directional differential electron flux data from Van Allen Probes, show that there was a significant energy-dependent relativistic electron dropout over a limited L-shell range during and after the EMIC wave activity. In addition, the NOAA spacecraft observed relativistic electron precipitation associated with the EMIC waves near the footprint of the Van Allen Probes spacecraft. The observations suggest EMIC wave-induced relativistic electron loss in the radiation belt

    Phenotypic and functional analyses show stem cell-derived hepatocyte-like cells better mimic fetal rather than adult hepatocytes

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    Background & Aims: Hepatocyte-like cells (HLCs), differentiated from pluripotent stem cells by the use of soluble factors, can model human liver function and toxicity. However, at present HLC maturity and whether any deficit represents a true fetal state or aberrant differentiation is unclear and compounded by comparison to potentially deteriorated adult hepatocytes. Therefore, we generated HLCs from multiple lineages, using two different protocols, for direct comparison with fresh fetal and adult hepatocytes. Methods: Protocols were developed for robust differentiation. Multiple transcript, protein and functional analyses compared HLCs to fresh human fetal and adult hepatocytes. Results: HLCs were comparable to those of other laboratories by multiple parameters. Transcriptional changes during differentiation mimicked human embryogenesis and showed more similarity to pericentral than periportal hepatocytes. Unbiased proteomics demonstrated greater proximity to liver than 30 other human organs or tissues. However, by comparison to fresh material, HLC maturity was proven by transcript, protein and function to be fetal-like and short of the adult phenotype. The expression of 81% phase 1 enzymes in HLCs was significantly upregulated and half were statistically not different from fetal hepatocytes. HLCs secreted albumin and metabolized testosterone (CYP3A) and dextrorphan (CYP2D6) like fetal hepatocytes. In seven bespoke tests, devised by principal components analysis to distinguish fetal from adult hepatocytes, HLCs from two different source laboratories consistently demonstrated fetal characteristics. Conclusions: HLCs from different sources are broadly comparable with unbiased proteomic evidence for faithful differentiation down the liver lineage. This current phenotype mimics human fetal rather than adult hepatocytes

    A new method for spatially resolving the turbulence driving mixture in the ISM with application to the Small Magellanic Cloud

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    Turbulence plays a crucial role in shaping the structure of the interstellar medium. The ratio of the three-dimensional density contrast (σρ/ρ0\sigma_{\rho/\rho_0}) to the turbulent sonic Mach number (M\mathcal{M}) of an isothermal, compressible gas describes the ratio of solenoidal to compressive modes in the turbulent acceleration field of the gas, and is parameterised by the turbulence driving parameter: b=σρ/ρ0/Mb=\sigma_{\rho/\rho_0}/\mathcal{M}. The turbulence driving parameter ranges from b=1/3b=1/3 (purely solenoidal) to b=1b=1 (purely compressive), with b=0.38b=0.38 characterising the natural mixture (1/3~compressive, 2/3~solenoidal) of the two driving modes. Here we present a new method for recovering σρ/ρ0\sigma_{\rho/\rho_0}, M\mathcal{M}, and bb, from observations on galactic scales, using a roving kernel to produce maps of these quantities from column density and centroid velocity maps. We apply our method to high-resolution HI emission observations of the Small Magellanic Cloud (SMC) from the GASKAP-HI survey. We find that the turbulence driving parameter varies between b0.3b\sim 0.3 and b1.0b\sim 1.0 within the main body of the SMC, but the median value converges to b0.51b\sim0.51, suggesting that the turbulence is overall driven more compressively (b>0.38b>0.38). We observe no correlation between the bb parameter and HI or Hα\alpha intensity, indicating that compressive driving of HI turbulence cannot be determined solely by observing HI or Hα\alpha emission density, and that velocity information must also be considered. Further investigation is required to link our findings to potential driving mechanisms such as star-formation feedback, gravitational collapse, or cloud-cloud collisions.Comment: 20 pages, 16 figures, accepted to MNRA

    Biomaterial-Based Implantable Devices for Cancer Therapy

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    This review article focuses on the current local therapies mediated by implanted macroscaled biomaterials available or proposed for fighting cancer and also highlights the upcoming research in this field. Several authoritative review articles have collected and discussed the state-of-the-art as well as the advancements in using biomaterial-based micro- and nano-particle systems for drug delivery in cancer therapy. On the other hand, implantable biomaterial devices are emerging as highly versatile therapeutic platforms, which deserve an increased attention by the healthcare scientific community, as they are able to offer innovative, more effective and creative strategies against tumors. This review summarizes the current approaches which exploit biomaterial-based devices as implantable tools for locally administrating drugs and describes their specific medical applications, which mainly target resected brain tumors or brain metastases for the inaccessibility of conventional chemotherapies. Moreover, a special focus in this review is given to innovative approaches, such as combined delivery therapies, as well as to alternative approaches, such as scaffolds for gene therapy, cancer immunotherapy and metastatic cell capture, the later as promising future trends in implantable biomaterials for cancer applications

    Epigenetics and developmental programming of welfare and production traits in farm animals

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    The concept that postnatal health and development can be influenced by events that occur in utero originated from epidemiological studies in humans supported by numerous mechanistic (including epigenetic) studies in a variety of model species. Referred to as the ‘developmental origins of health and disease’ or ‘DOHaD’ hypothesis, the primary focus of large-animal studies until quite recently had been biomedical. Attention has since turned towards traits of commercial importance in farm animals. Herein we review the evidence that prenatal risk factors, including suboptimal parental nutrition, gestational stress, exposure to environmental chemicals and advanced breeding technologies, can determine traits such as postnatal growth, feed efficiency, milk yield, carcass composition, animal welfare and reproductive potential. We consider the role of epigenetic and cytoplasmic mechanisms of inheritance, and discuss implications for livestock production and future research endeavours. We conclude that although the concept is proven for several traits, issues relating to effect size, and hence commercial importance, remain. Studies have also invariably been conducted under controlled experimental conditions, frequently assessing single risk factors, thereby limiting their translational value for livestock production. We propose concerted international research efforts that consider multiple, concurrent stressors to better represent effects of contemporary animal production systems

    Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

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    [This corrects the article DOI: 10.1186/s13054-016-1208-6.]

    A critical appraisal of the social norms approach as an interventional strategy for health-related behavior and attitude change

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    © 2018 Dempsey, McAlaney and Bewick. The Social Norms Approach is a widely used intervention strategy for promoting positive health-related behaviors. The Approach operates on the premise that individuals misperceive their peers' behaviors and attitudes, with evidence of under- and over-estimations of behaviors and peer approval for a range of positive and negative behaviors respectively. The greater these misperceptions, the more likely an individual is to engage in negative behaviors such as consuming heavier amounts of alcohol and other substances and reduce positive behaviors such as eating healthily and using sun protection. However, there are many complexities associated with the use of social norms feedback in interventions and empirical studies. Many social norms interventions do not attempt to change misperceptions of social norms or measure changes in normative perceptions pre- and post-intervention. This has led to a conflation of generic social norms interventions with those that are explicitly testing the Approach's assumptions that it is misperceptions of peer norms which drive behavior. The aim of the present review was to provide a critical appraisal of the use of the Social Norms Approach as an intervention strategy for health-related behaviors, identify the current issues with its evidence base, highlight key opportunities and challenges facing the approach, and make recommendations for good practice when using the approach. There are three core challenges and areas for improved practice when using the Social Norms Approach. Firstly, improvements in the methodological rigor and clarity of reporting of 'social norms' research, ensuring that studies are testing the approach's assumption of the role of misperceptions on behaviors are differentiated from studies investigating other forms of 'social norms.' Secondly, the need for a more explicit, unified and testable theoretical model outlining the development of normative misperceptions which can be translated into interventional studies. Finally, a need for a more robust evaluation of social norms interventions in addition to randomized controlled trials, such as the inclusion of process evaluations, qualitative studies of participant experiences of social norms feedback, and alternative study designs better suited for real-world public health settings. Such improvements are required to ensure that the Social Norms Approach is adequately tested and evaluated

    Annual banned-substance review: Analytical approaches in human sports drug testing.

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    A number of high profile revelations concerning anti-doping rule violations over the past 12 months have outlined the importance of tackling prevailing challenges and reducing the limitations of the current anti-doping system. At this time, the necessity to enhance, expand, and improve analytical test methods in response to the substances outlined in the World Anti-Doping Agency (WADA) Prohibited List represents an increasingly crucial task for modern sports drug testing programs. The ability to improve analytical testing methods often relies on the expedient application of novel information regarding superior target analytes for sports drug testing assays, drug elimination profiles, and alternative sample matrices, together with recent advances in instrumental developments. This annual banned-substance review evaluates literature published between October 2017 and September 2018 offering an in-depth evaluation of developments in these arenas and their potential application to substances reported in WADA's 2018 Prohibited List
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