459 research outputs found

    Cold streams of ionospheric oxygen in the plasma sheet during the CDAW-6 event of March 22, 1979

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    During magnetospheric substorm events, the plasma and ion composition experiments in the ISEE-1 and 2 satellites detected cold ionospheric O+ streams, moving tailwards in the near Earth magnetotail. Flow is parallel to the magnetic field lines, with drift velocity in agreement with the electric field topology obtained by mapping the model ionospheric field along the magnetic field lines. Fluctuations of the flow velocity of the streams can be related to magnetotail movements. Oscillations of the flow direction and speed with periods ranging from 5 to 10 min that suggest the presence of waves are observed. The streams are observed at all distances between 15 and 6 Re from the Earth. When averaged over 360 deg, the streams show up as a low energy peak, superimposed on the distribution of isotropic plasma sheet ions. This double-peak structure of the energy spectrum seems typical of the disturbed plasma sheet

    Experimental investigation of possible geomagnetic feedback from energetic (0.1 to 16 keV) terrestrial O(+) ions in the magnetotail current sheet

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    Data from energetic ion mass spectrometers on the ISEE 1 and AMPTE/CCE spacecraft are combined with geomagnetic and solar indices to investigate, in a statistical fashion, whether energized O(+) ions of terrestrial origin constitute a source of feedback which triggers or amplifies geomagnetic activity as has been suggested in the literature, by contributing a destabilizing mass increase in the magnetotail current sheet. The ISEE 1 data (0.1-16 keV/e) provide in situ observations of the O(+) concentration in the central plasma sheet, inside of 23 R(sub E), during the rising and maximum phases of solar cycle 21, as well as inner magnetosphere data from same period. The CCE data (0.1-17 keV/e) taken during the subsequent solar minimum all within 9 R(sub E). provide a reference for long-term variations in the magnetosphere O(+) content. Statistical correlations between the ion data and the indices, and between different indices. all point in the same direction: there is probably no feedback specific to the O(+) ions, in spite of the fact that they often contribute most of the ion mass density in the tail current sheet

    Impacts of roads on bird species richness: A meta-analysis considering road types, habitats and feeding guilds

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    Roadsides can harbour remarkable biodiversity; thus, they are increasingly considered as habitats with potential for conservation value. To improve construction and management of roadside habitats with positive effects on biodiversity, we require a quantitative understanding of important influential factors that drive both positive and negative effects of roads. We conducted meta-analyses to assess road effects on bird communities. We specifically tested how the relationship between roads and bird richness varies when considering road type, habitat characteristics and feeding guild association. Overall, bird richness was similar in road habitats compared to non-road habitats, however, the two apparently differ in species composition. Bird richness was lowered by road presence in areas with denser tree cover but did not differ according to road type. Richness differences between habitats with and without roads further depended on primary diet of species, and richness of omnivores was positively affected by road presence. We conclude that impacts of roads on bird richness are highly context-dependent, and planners should carefully evaluate road habitats on a case by case basis. This emphasizes the need for further studies that explicitly test for differences in species composition and abundance, to disentangle contexts where a road will negatively affect bird communities, and where it will not

    Diurnal salivary cortisol concentrations in Parkinson’s disease: increased total secretion and morning cortisol concentrations

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    Background:Parkinson’s disease (PD) is a chronic neurodegenerative disorder. There is limited knowledge about the function of the hypothalamic-pituitary-adrenal axis in PD. The primary aim of this prospective study was to analyze diurnal salivary cortisol concentrations in patients with PD and correlate these with age, gender, body mass index (BMI), duration of PD, and pain. The secondary aim was to compare the results with a healthy reference group. Methods:Fifty-nine PD patients, 35 women and 24 men, aged 50–79 years, were recruited. The reference group comprised healthy individuals matched for age, gender, BMI, and time point for sampling. Salivary cortisol was collected at 8 am, 1 pm, and 8 pm, and 8 am the next day using cotton-based Salivette ®tubes and analyzed using Spectria®Cortisol I125. A visual analog scale was used for estimation of pain. Results:The median cortisol concentration was 16.0 (5.8–30.2) nmol/L at 8 am, 5.8 (3.0–16.4) at 1 pm, 2.8 (1.6–8.0) at 8 pm, and 14.0 (7.5–28.7) at 8 am the next day. Total secretion and rate of cortisol secretion during the day (8 am–8 pm) and the concentration of cortisol on the next morning were lower (12.5 nmol/L) in the reference group. No significant correlations with age, gender, BMI, duration of PD, Hoehn and Yahr score, Unified Parkinson’s Disease Rating Scale III score, gait, pain, or cortisol concentrations were found. Conclusion:The neurodegenerative changes in PD does not seem to interfere with the hypothalamic-pituitary-adrenal axis. Salivary cortisol concentrations in PD patients were increased in the morning compared with the reference group, and were not influenced by motor dysfunction, duration of disease, or coexistence of chronic or acute pain

    Perceived Stress at Work Is Associated with Lower Levels of DHEA-S

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    Abstract Background: It is known that long-term psychosocial stress may cause or contribute to different diseases and symptoms and accelerate aging. One of the consequences of prolonged psychosocial stress may be a negative effect on the levels of dehydroepiandrosterone (DHEA) and its sulphated metabolite dehydroepiandrosterone sulphate (DHEA-S)

    Induced pluripotent stem cell-derived endothelial cells promote angiogenesis and accelerate wound closure in a murine excisional wound healing model

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    Chronic wounds are a major complication in patients with cardiovascular diseases. Cell therapies have shown potential to stimulate wound healing, but clinical trials using adult stem cells have been tempered by limited numbers of cells and invasive procurement procedures. Induced pluripotent stem cells (iPSCs) have several advantages of other cell types, for example they can be generated in abundance from patients’ somatic cells (autologous) or those from a matched donor. iPSCs can be efficiently differentiated to functional endothelial cells (iPSC-ECs). Here, we used a murine excisional wound model to test the pro-angiogenic properties of iPSC-ECs in wound healing. Two full-thickness wounds were made on the dorsum of NOD-SCID mice and splinted. iPSC-ECs (5 × 105) were topically applied to one wound, with the other serving as a control. Treatment with iPSC-ECs significantly increased wound perfusion and accelerated wound closure. Expression of endothelial cell (EC) surface marker, platelet endothelial cell adhesion molecule (PECAM-1) (CD31), and pro-angiogenic EC receptor, Tie1, mRNA was up-regulated in iPSC-EC treated wounds at 7 days post-wounding. Histological analysis of wound sections showed increased capillary density in iPSC-EC wounds at days 7 and 14 post-wounding, and increased collagen content at day 14. Anti-GFP fluorescence confirmed presence of iPSC-ECs in the wounds. Bioluminescent imaging (BLI) showed progressive decline of iPSC-ECs over time, suggesting that iPSC-ECs are acting primarily through short-term paracrine effects. These results highlight the pro-regenerative effects of iPSC-ECs and demonstrate that they are a promising potential therapy for intractable wounds.Zoë E. Clayton, Richard P. Tan, Maria M. Miravet, Katarina Lennartsson, John P. Cooke, Christina A. Bursill, Steven G. Wise, Sanjay Pate
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