445 research outputs found

    Generalized Painleve-Gullstrand descriptions of Kerr-Newman black holes

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    Generalized Painleve-Gullstrand metrics are explicitly constructed for the Kerr-Newman family of charged rotating black holes. These descriptions are free of all coordinate singularities; moreover, unlike the Doran and other proposed metrics, an extra tunable function is introduced to ensure all variables in the metrics remain real for all values of the mass M, charge Q, angular momentum aM, and cosmological constant \Lambda > - 3/(a^2). To describe fermions in Kerr-Newman spacetimes, the stronger requirement of non-singular vierbein one-forms at the horizon(s) is imposed and coordinate singularities are eliminated by local Lorentz boosts. Other known vierbein fields of Kerr-Newman black holes are analysed and discussed; and it is revealed that some of these descriptions are actually not related by physical Lorentz transformations to the original Kerr-Newman expression in Boyer-Lindquist coordinates - which is the reason complex components appear (for certain ranges of the radial coordinate) in these metrics. As an application of our constructions the correct effective Hawking temperature for Kerr black holes is derived with the method of Parikh and Wilczek.Comment: 5 pages; extended to include application to derivation of Hawking radiation for Kerr black holes with Parikh-Wilczek metho

    The consequences of niche and physiological differentiation of archaeal and bacterial ammonia oxidisers for nitrous oxide emissions

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    The authors are members of the Nitrous Oxide Research Alliance (NORA), a Marie Skłodowska-Curie ITN and research project under the EU's seventh framework program (FP7). GN is funded by the AXA Research Fund and CGR by a Royal Society University Research Fellowship (UF150571) and a Natural Environment Research Council (NERC) Standard Grant (NE/K016342/1). The authors would like to thank Dr Robin Walker and the SRUC Craibstone Estate (Aberdeen) for access to the agricultural plots, Dr Alex Douglas for statistical advice and Philipp Schleusner for assisting microcosm construction and sampling.Peer reviewedPublisher PD

    Non-solvolytic synthesis of aqueous soluble TiO2 nanoparticles and real-time dynamic measurements of the nanoparticle formation.

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    Highly aqueously dispersible (soluble) TiO2 nanoparticles are usually synthesized by a solution-based sol-gel (solvolysis/condensation) process, and no direct precipitation of titania has been reported. This paper proposes a new approach to synthesize stable TiO2 nanoparticles by a non-solvolytic method - direct liquid phase precipitation at room temperature. Ligand-capped TiO2 nanoparticles are more readily solubilized compared to uncapped TiO2 nanoparticles, and these capped materials show distinct optical absorbance/emission behaviors. The influence of ligands, way of reactant feeding, and post-treatment on the shape, size, crystalline structure, and surface chemistry of the TiO2 nanoparticles has been thoroughly investigated by the combined use of X-ray diffraction, transmission electron microscopy, UV-visible (UV-vis) spectroscopy, and photoluminescence (PL). It is found that all above variables have significant effects on the size, shape, and dispersivity of the final TiO2 nanoparticles. For the first time, real-time UV-vis spectroscopy and PL are used to dynamically detect the formation and growth of TiO2 nanoparticles in solution. These real-time measurements show that the precipitation process begins to nucleate after an initial inhibition period of about 1 h, thereafter a particle growth occurs and reaches the maximum point after 2 h. The synthesis reaction is essentially completed after 4 h.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

    TonEBP suppresses adipogenesis and insulin sensitivity by blocking epigenetic transition of PPAR gamma 2

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    TonEBP is a key transcription factor in cellular adaptation to hypertonic stress, and also in macrophage activation. Since TonEBP is involved in inflammatory diseases such as rheumatoid arthritis and atherosclerosis, we asked whether TonEBP played a role in adipogenesis and insulin resistance. Here we report that TonEBP suppresses adipogenesis and insulin signaling by inhibiting expression of the key transcription factor PPAR gamma 2. TonEBP binds to the PPAR gamma 2 promoter and blocks the epigenetic transition of the locus which is required for the activation of the promoter. When TonEBP expression is reduced, the epigenetic transition and PPAR gamma 2 expression are markedly increased leading to enhanced adipogenesis and insulin response while inflammation is reduced. Thus, TonEBP is an independent determinant of adipose insulin sensitivity and inflammation. TonEBP is an attractive therapeutic target for insulin resistance in lieu of PPAR gamma agonistsopen0

    International expert consensus on the management of bleeding during VATS lung surgery

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    Intraoperative bleeding is the most crucial safety concern of video-assisted thoracic surgery (VATS) for a major pulmonary resection. Despite the advances in surgical techniques and devices, intraoperative bleeding is still not rare and remains the most common and potentially fatal cause of conversion from VATS to open thoracotomy. Therefore, to guide the clinical practice of VATS lung surgery, we proposed the International Interest Group on Bleeding during VATS Lung Surgery with 65 experts from 10 countries in the field to develop this consensus document. The consensus was developed based on the literature reports and expert experience from different countries. The causes and incidence of intraoperative bleeding were summarised first. Seven situations of intraoperative bleeding were collected based on clinical practice, including the bleeding from massive vessel injuries, bronchial arteries, vessel stumps, and bronchial stumps, lung parenchyma, lymph nodes, incisions, and the chest wall. The technical consensus for the management of intraoperative bleeding was achieved on these seven surgical situations by six rounds of repeated revision. Following expert consensus statements were achieved: (I) Bleeding from major vascular injuries: direct compression with suction, retracted lung, or rolled gauze is useful for bleeding control. The size and location of the vascular laceration are evaluated to decide whether the bleeding can be stopped by direct compression or by ligation. If suturing is needed, the suction-compressing angiorrhaphy technique (SCAT) is recommended. Timely conversion to thoracotomy with direct compression is required if the operator lacks experience in thoracoscopic angiorrhaphy. (II) Bronchial artery bleeding: pre-emptive clipping of bronchial artery before bronchial dissection or lymph node dissection can reduce the incidence of bleeding. Bronchial artery bleeding can be stopped by compression with the suction tip, followed by the handling of the vascular stump with energy devices or clips. (III) Bleeding from large vessel stumps and bronchial stumps: bronchial stump bleeding mostly comes from accompanying bronchial artery, which can be clipped for hemostasis. Compression for hemostasis is usually effective for bleeding at the vascular stump. Otherwise, additional use of hemostatic materials, re-staple or a suture may be necessary. (IV) Bleeding from the lung parenchyma: coagulation hemostasis is the first choice. For wounds with visible air leakage or an insufficient hemostatic effect of coagulation, suturing may be necessary. (V) Bleeding during lymph node dissection: non-grasping en-bloc lymph node dissection is recommended for the nourishing vessels of the lymph node are addressed first with this technique. If bleeding occurs at the site of lymph node dissection, energy devices can be used for hemostasis, sometimes in combination with hemostatic materials. (VI) Bleeding from chest wall incisions: the chest wall incision(s) should always be made along the upper edge of the rib(s), with good hemostasis layer by layer. Recheck the incision for hemostasis before closing the chest is recommended. (VII) Internal chest wall bleeding: it can usually be managed with electrocoagulation. For diffuse capillary bleeding with the undefined bleeding site, compression of the wound with gauze may be helpful

    Transcriptional Homeostasis of a Mangrove Species, Ceriops tagal, in Saline Environments, as Revealed by Microarray Analysis

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    <div><h3>Background</h3><p>Differential responses to the environmental stresses at the level of transcription play a critical role in adaptation. Mangrove species compose a dominant community in intertidal zones and form dense forests at the sea-land interface, and although the anatomical and physiological features associated with their salt-tolerant lifestyles have been well characterized, little is known about the impact of transcriptional phenotypes on their adaptation to these saline environments.</p> <h3>Methodology and Principal findings</h3><p>We report the time-course transcript profiles in the roots of a true mangrove species, <em>Ceriops tagal</em>, as revealed by a series of microarray experiments. The expression of a total of 432 transcripts changed significantly in the roots of <em>C. tagal</em> under salt shock, of which 83 had a more than 2-fold change and were further assembled into 59 unigenes. Global transcription was stable at the early stage of salt stress and then was gradually dysregulated with the increased duration of the stress. Importantly, a pair-wise comparison of predicted homologous gene pairs revealed that the transcriptional regulations of most of the differentially expressed genes were highly divergent in <em>C. tagal</em> from that in salt-sensitive species, <em>Arabidopsis thaliana</em>.</p> <h3>Conclusions/Significance</h3><p>This work suggests that transcriptional homeostasis and specific transcriptional regulation are major events in the roots of <em>C. tagal</em> when subjected to salt shock, which could contribute to the establishment of adaptation to saline environments and, thus, facilitate the salt-tolerant lifestyle of this mangrove species. Furthermore, the candidate genes underlying the adaptation were identified through comparative analyses. This study provides a foundation for dissecting the genetic basis of the adaptation of mangroves to intertidal environments.</p> </div
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