44 research outputs found

    Interhemispheric asymmetries of neutral upwelling and ion upflow

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    This work addresses interhemispheric differences in cusp-related neutral density enhancements. The focus is on enhancements that are driven by Poleward Moving Auroral Forms (PMAF), which provide a repetitive sequence of soft electron precipitation to the ionosphere. Because the time-scales of the resultant electron heating, ion upflow and neutral upwelling range from a few seconds to tens of minutes, i.e., longer than the time required for the thermosphere to return to its relaxed state, each subsequent PMAF encounters different initial conditions. With this in mind, our study investigates the role of a dark versus daylight ionosphere, using 3 different scenarios. The first case compares this effect during solar minimum at Longyearbyen, Svalbard, an ideal location for observing cusp dynamics. The second case addresses solar maximum at Longyearbyen and the third case compares Longyearbyen to its magnetically conjugate Zhongshan Station in Antarctica. We conclude 1) for each of the 3 scenarios ion upflow speeds, neutral upwelling speeds and neutral density enhancements are all significantly greater in a dark ionosphere, by perhaps as much as a factor or 2 or 3, relative to a sunlit ionosphere, 2) that upflowing ions are the driver of neutral upwelling via ion-neutral collisions (momentum transfer), with fast-moving ions transferring upward momentum to slow-moving neutrals, and 3) the ratios of neutral upflow speeds to ion upflow speeds, vnSunlit/viSunlit is the order of 0.07 for all stations (at 800 km) in the first and second cases studied, but only 0.02 at Zhongshan in the 3rd case studied, a factor of ∼3 less than the other locations. This is thought to be due to an increased thermospheric density at Zhongshan, which essentially provides a greater total mass for the upflowing ions to lift

    Parental reflective functioning: Theory, research, and clinical applications

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    This paper reviews recent theoretical, empirical, and clinical work related to parental reflective functioning (PRF) or parental mentalizing. PRF refers to the capacity of the parent to envision his/her child as being motivated by internal mental states such as feelings, wishes, and desires, and to be able to reflect upon his/her own internal mental experiences and how they are shaped and changed by interactions with the child. This paper first briefly discuss the historical and theoretical background of this concept and its purported role in child development, with a focus on the development of child attachment, affect regulation, and mentalizing. It then reviews recent thinking and research in four areas: (a) the neurobiology underlying PRF, (b) the multidimensionality of PRF, (c) the relationship between PRF and trauma, and (d) the broader relevance of attention to internal mental states for the development of epistemic trust as the basis of an evolutionary inbuilt capacity for learning from and within social communication. It closes with a brief review of the background of and empirical evidence supporting interventions rooted in theoretical considerations concerning the importance of PRF, as well as suggesting directions for future research and clinical practice

    The different faces of metastatic melanoma in the gastrointestinal tract.

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    Melanoma is the most aggressive form of skin cancer, with tendency to spread to any organ of the human body, including the gastrointestinal tract (GIT). The diagnosis of metastases to the GIT can be difficult, as they may be clinically silent for somewhile and may occur years after the initial melanoma diagnosis. CT imaging remains the standard modality for staging and surveillance of melanoma patients, and in most cases, it will be the first imaging modality to identify GIT lesions. However, interpretation of CT studies in patients with melanoma can be challenging as lesions may be subtle and random in distribution, as well as sometimes mimicking other conditions. Even so, early diagnosis of GIT metastases is critical to avoid emergency hospitalisations, whilst surgical intervention can be curative in some cases. In this review, we illustrate the various imaging presentations of melanoma metastases within the GIT, discuss the clinical aspects and offer advice on investigation and management. We offer tips intended to aid radiologists in their diagnostic skills and interpretation of melanoma imaging scans

    The forgotten appearance of metastatic melanoma in the small bowel.

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    BACKGROUND: Melanoma is the most aggressive form of skin cancer, with a tendency to metastasise to any organ of the human body. While the most common body organs affected include liver, lungs, brain and soft tissues, spread to the gastrointestinal tract is not uncommon. In the bowel, it can present with a multitude of imaging appearances, more rarely as an aneurysmal dilatation. This appearance is classically associated with lymphoma, but it has more rarely been associated with other forms of malignancy. CASE PRESENTATION: We report a case series of three patients with aneurysmal dilatation in the small bowel (SB) confirmed to be due to metastatic melanoma (MM). All patients had non-specific symptoms; most times being attributed initially to causes other than melanoma. On CT the identified aneurysmal SB dilatations were diagnosed as presumed lymphoma in all cases. In two cases, the aneurysmal dilatation was the first presentation of metastatic disease and in two of the cases more than one site of the gastrointestinal tract was concomitantly involved. All patients underwent surgical resection with histological confirmation of MM. CONCLUSIONS: Recognition of unusual SB presentation of MM, such as aneurysmal SB dilatation, is important to expedite diagnosis, provide appropriate treatment, and consequently improve quality of life and likely survival of these patients. As the most common cancer to metastasise to the SB and as a known imaging mimicker, MM should remain in any radiologist's differential diagnosis for SB lesions with aneurysmal dilatation.Acknowledgements The authors acknowledge support from National Institute of Health Research Cambridge Biomedical Research Centre, Cancer Research UK (Cambridge Imaging Centre grant number C197/A16465), the Engineering and Physical Sciences Research Council Imaging Centre in Cambridge and Manchester and the Cambridge Experimental Cancer Medicine Centre. Funding source and conflicts of interest E.M.S is funded by NIHR Clinical Lectureship (Reference number: NIHR CL-2017-14-502) and is also supported by the Academy of Medical Sciences, the Wellcome Trust, the Medical Research Council (MRC), the British Heart Foundation, Versus Arthritis, Diabetes UK and the British Thoracic Society (Helen and Andrew Douglas bequest) Starter Grant award [SGL019\1007]. The views expressed are those of the authors and not necessarily those of the funders. No conflicts of interest to disclosure

    The Nalp3 inflammasome is essential for the development of silicosis

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    Inhalation of crystalline silica and asbestos is known to cause the progressive pulmonary fibrotic disorders silicosis and asbestosis, respectively. Although alveolar macrophages are believed to initiate these inflammatory responses, the mechanism by which this occurs has been unclear. Here we show that the inflammatory response and subsequent development of pulmonary fibrosis after inhalation of silica is dependent on the Nalp3 inflammasome. Stimulation of macrophages with silica results in the activation of caspase-1 in a Nalp3-dependent manner. Macrophages deficient in components of the Nalp3 inflammasome were incapable of secreting the proinflammatory cytokines interleukin (IL)-1β and IL-18 in response to silica. Similarly, asbestos was capable of activating caspase-1 in a Nalp3-dependent manner. Activation of the Nalp3 inflammasome by silica required both an efflux of intracellular potassium and the generation of reactive oxygen species. This study demonstrates a key role for the Nalp3 inflammasome in the pathogenesis of pneumoconiosis
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