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We prove the nonlinear stability of the asymptotic behaviour of perturbations of subfamilies of Kasner solutions in the contracting time direction within the class of polarized [Formula: see text]-symmetric solutions of the vacuum Einstein equations with arbitrary cosmological constant [Formula: see text]. This stability result generalizes the results proven in Ames E et al. (2022 Stability of AVTD Behavior within the Polarized [Formula: see text]-symmetric vacuum spacetimes. Ann. Henri Poincaré. (doi:10.1007/s00023-021-01142-0)), which focus on the [Formula: see text] case, and as in that article, the proof relies on an areal time foliation and Fuchsian techniques. Even for [Formula: see text], the results established here apply to a wider class of perturbations of Kasner solutions within the family of polarized [Formula: see text]-symmetric vacuum solutions than those considered in Ames E et al. (2022 Stability of AVTD Behavior within the Polarized [Formula: see text]-symmetric vacuum spacetimes. Ann. Henri Poincaré. (doi:10.1007/s00023-021-01142-0)) and Fournodavlos G et al. (2020 Stable Big Bang formation for Einstein's equations: the complete sub-critical regime. Preprint. (http://arxiv.org/abs/2012.05888)). Our results establish that the areal time coordinate takes all values in [Formula: see text] for some [Formula: see text], for certain families of polarized [Formula: see text]-symmetric solutions with cosmological constant. This article is part of the theme issue 'The future of mathematical cosmology, Volume 1'.
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Peatland rewetting aims at stopping the emissions of carbon dioxide (CO2) and establishing net carbon sinks. However, in times of global warming, restoration projects must increasingly deal with extreme events such as drought periods. Here, we evaluate the effect of the European summer drought 2018 on vegetation development and the exchange of methane (CH4) and CO2 in two rewetted minerotrophic fens (Hütelmoor-Hte and Zarnekow-Zrk) including potential carry-over effects in the post-drought year. Drought was a major stress factor for the established vegetation but also promoted the rapid spread of new vegetation, which will likely gain a lasting foothold in Zrk. Accordingly, drought increased not only respiratory CO2 losses but also photosynthetic CO2 uptake. Altogether, the drought reduced the net CO2 sink in Hte, while it stopped the persistent net CO2 emissions of Zrk. In addition, the drought reduced CH4 emissions in both fens, though this became most apparent in the post-drought year and suggests a lasting shift towards non-methanogenic organic matter decomposition. Occasional droughts can be beneficial for the restoration of the peatland carbon sink function if the newly grown vegetation increases CO2 sequestration in the long term. Nonetheless, care must be taken to prevent extensive peat decay. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.
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Cambio Climático , Sequías , Gases de Efecto Invernadero/análisis , Fenómenos Fisiológicos de las Plantas , Humedales , Dióxido de Carbono/análisis , Secuestro de Carbono , Europa (Continente) , Calentamiento Global , Dispersión de las PlantasRESUMEN
Membrane filtration systems are widely applied for the production of clean drinking water. However, the accumulation of particles on synthetic membranes leads to fouling. Biological fouling (i.e., biofouling) of reverse osmosis and nanofiltration membranes is difficult to control by existing cleaning procedures. Improved strategies are therefore needed. The bacterial diversity on fouled membranes has been studied, especially to identify bacteria with specialized functions and to develop targeted approaches against these microbes. Previous studies have shown that Sphingomonadaceae are initial membrane colonizers that remain dominant while the biofilm develops. Here, we characterized 21 Sphingomonadaceae isolates, obtained from six different fouled membranes, to determine which physiological traits could contribute to colonization of membrane surfaces. Their growth conditions ranged from temperatures between 8 and 42 oC, salinity between 0.0 and 5.0% w/v NaCl, pH from 4 and 10, and all isolates were able to metabolize a wide range of substrates. The results presented here show that Sphingomonadaceae membrane isolates share many features that are uncommon for other members of the Sphingomonadaceae family: all membrane isolates are motile and their tolerance for different temperatures, salt concentrations, and pH is high. Although relative abundance is an indicator of fitness for a whole group, for the Sphingomonadaceae it does not reveal the specific physiological traits that are required for membrane colonization. This study, therefore, adds to more fundamental insights in membrane biofouling.
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Incrustaciones Biológicas , Membranas/microbiología , Sphingomonadaceae/crecimiento & desarrollo , Sphingomonadaceae/metabolismo , Filtración/métodos , Concentración de Iones de Hidrógeno , Locomoción , Metabolismo , Cloruro de Sodio/metabolismo , Sphingomonadaceae/aislamiento & purificación , Temperatura , Purificación del Agua/métodosRESUMEN
A strictly anaerobic bacterium, strain DLD10T, was isolated from a biofilm that developed on a nanofiltration membrane treating anoxic groundwater using glycerol as substrate. Cells were straight to slightly curved rods 0.2-0.5 µm in diameter and 1-3 µm in length, non-motile and non-spore-forming. The optimum temperature and pH for growth were 30 °C and pH 7.0. Strain DLD10T was able to grow in the presence of 0.03-4.5â% (w/v) NaCl. Substrates utilized by strain DLD10T included glycerol and various carbohydrates (glucose, sucrose, fructose, mannose, arabinose, pectin, starch, xylan), which were mainly converted to ethanol, acetate, H2 and formate. Thiosulphate, sulphur and Fe(III) were used as electron acceptors, but sulphate, fumarate and nitrate were not. The predominant membrane fatty acids were C16â:â0, iso-C17â:â1 and C17â:â1ω8c. The DNA G+C content was 36.4âmol%. Strain DLD10T belongs to the family Lachnospiraceae and is distantly related to Clostridium populeti DSM 5832T, Hespellia porcina DSM 15481T and Robinsoniella peoriensis CCUG 48729T (93â% 16S rRNA gene sequence similarity). Physiological characteristics and phylogenetic analysis indicated that strain DLD10T is a representative of a novel species of a new genus, for which the name Lachnotalea glycerini gen. nov., sp. nov. is proposed. The type strain of Lachnotalea glycerini is DLD10T ( = DSM 28816T = JCM 30818T).
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OBJECTIVE: Comparison of 2-dimensional and semiautomated 3-dimensional (3D) measurements to distinguish between benign and malignant lymph nodes in patients with malignant lymphoma. METHODS: Whole-body positron emission tomography-computed tomography (PET-CT) was performed in 33 patients before therapy for malignant lymphoma. Two hundred fifty-seven peripheral lymph nodes (mean size, 13.4 +/- 5.4 mm) were evaluated independently by 2 radiologists, both manually and with the use of semiautomated segmentation software. Long-axis diameter (LAD), short-axis diameter (SAD), maximal 3D diameter, volume, and elongation were measured. Positron emission tomography-CT and PET-CT follow-up and/or histology served as the reference standard. Statistical analysis encompassed intraclass correlation coefficients and receiver operating characteristic curves. RESULTS: The standard of reference revealed involvement in 116 (45%) of 257 lymph nodes. Manual and semiautomated LAD and SAD showed good correlation with intraclass coefficients of 0.85 and 0.72, respectively. Semiautomated prediction of malignant lymph nodes revealed the highest areas under the receiver operating characteristic curves for volume (0.760; 95% confidence interval [CI], 0.639-0.887) followed by SAD (0.740; 95% CI, 0.616-0.862). The findings for LAD (0.722; 95% CI, 0.588-0.855), maximal 3D diameter (0.697; 95% CI, 0.565-0.830), and lymph node elongation (0.605; 95% CI, 0.466-0.745) were significantly lower (P < 0.05). CONCLUSIONS: Volumetric lymph node analysis is significantly superior compared with established LAD in the prediction of lymph node involvement and therefore can add to the definition of peripheral lymphoma target lesions.
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Ganglios Linfáticos/diagnóstico por imagen , Linfoma/diagnóstico por imagen , Tomografía de Emisión de Positrones/métodos , Tomografía Computarizada por Rayos X/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Tomografía Computarizada de Haz Cónico/métodos , Medios de Contraste , Diagnóstico Diferencial , Femenino , Humanos , Imagenología Tridimensional/métodos , Yohexol/análogos & derivados , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Valor Predictivo de las Pruebas , Curva ROC , Intensificación de Imagen Radiográfica/métodos , Reproducibilidad de los Resultados , Imagen de Cuerpo Entero/métodos , Adulto JovenRESUMEN
OBJECTIVES: To determine the impact of slice thickness on semiautomatic lymph node analysis. MATERIALS AND METHODS: Thoracic multislice computed tomography (MSCT) of 46 patients with NSCLC were reconstructed at 1.0-, 3.0-, and 5.0-mm slice thickness. Two radiologists independently determined long and short axis diameter and volume of 299 thoracic lymph nodes by semiautomatic segmentation software. Necessity of manual correction (= relative difference between uncorrected and corrected segmented lymph node volume) and relative interobserver differences were determined. The precision of segmentation was expressed by relative measurement deviations (RMD) from the reference standard (mean of 1.0 mm datasets). Statistical analysis encompassed t test and Bland-Altman plots. RESULTS: Necessity of manual correction was significantly higher for 5.0 mm than for 3.0 (P = 0.042) or 1.0 mm (P = 0.0012). The RMD for long and short axis diameter were found to be independent of slice thickness, whereas the RMD for lymph node volume significantly (P = 0.021) increased from 4.0% at 1.0 mm (95% CI: 1.0%-3.5%) to 35% at 5.0 mm (95% CI: 10.5%-60.5%). The relative interobserver differences was consistently low for metric and volumetric parameters (eg, volume 2.3%, 95% CI: -7.4%-10.8% at 5.0 mm) with no difference in any of the slice thicknesses (P > 0.064). CONCLUSIONS: Significant deviations in lymph node volume together with excessive manual corrections suggest reconstruction of the data for semiautomatic lymph node assessment at a slice thickness of 1.0 mm but not exceeding 3.0 mm.
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Carcinoma de Pulmón de Células no Pequeñas/diagnóstico por imagen , Carcinoma de Pulmón de Células no Pequeñas/secundario , Neoplasias Pulmonares/diagnóstico por imagen , Ganglios Linfáticos/diagnóstico por imagen , Reconocimiento de Normas Patrones Automatizadas/métodos , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Tomografía Computarizada por Rayos X/métodos , Algoritmos , Femenino , Humanos , Imagenología Tridimensional/métodos , Metástasis Linfática , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Intensificación de Imagen Radiográfica/métodos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
OBJECTIVE: In vitro endothelialization has significantly improved the overall outcome of artificial prostheses in cardiovascular bypass surgery. A drawback of this tissue-engineering method remains the limited availability of suitable autologous endothelial cells (EC), especially in aged patients. Allogeneic EC with high proliferative capacity represent a potentially valuable alternative to a patient-specific vascular transplant. However, such cells carry the risk of being rejected due to Major Histocompatibility Complex (MHC) mismatches. METHODS: We investigated the effects of a very potent, intracellularly expressed antibody directed against MHC class I molecules, referred to as alpha-rat MHC I single chain variable fragment (sFv) intrabody. The intrabody was stably expressed in rat aortic EC (RAEC) following lentiviral vector-mediated gene transfer. The functional consequence of the MHC I down-regulation was tested in an allogeneic setting in two different in vitro assays. RESULTS: Stable expression of the alpha-rat MHC I sFv intrabody resulted in a highly efficient depletion of surface MHC I. Thereby those RAEC which displayed low MHC I levels over extended periods of time were protected against killing by allo-specific, cytotoxic T cells (CTL) and by allo-antibody/complement-mediated lysis. CONCLUSIONS: These results demonstrate that intrabody-mediated down-regulation of MHC I reduces the immunogenicity of RAEC which may provide a suitable alternative supply for the lining of vascular prostheses.
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Células Endoteliales/inmunología , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/inmunología , Factores Inmunológicos/inmunología , Linfocitos T Citotóxicos/inmunología , Animales , Anticuerpos Monoclonales/genética , Citotoxicidad Inmunológica , Regulación hacia Abajo , Citometría de Flujo , Fragmentos de Inmunoglobulinas/genética , Líquido Intracelular/inmunología , Isoanticuerpos/inmunología , Ratas , Estadísticas no Paramétricas , Transducción Genética/métodos , Trasplante HomólogoRESUMEN
The purpose of this study was to assess the effectiveness of double reading to increase the sensitivity of lung nodule detection at standard-dose (SDCT) and low-dose multirow-detector CT (LDCT). SDCT (100 mAs effective tube current) and LDCT (20 mAs) of nine patients with pulmonary metastases were obtained within 5 min using four-row detector CT. Softcopy images reconstructed with 5-mm slice thickness were read by three radiologists independently. Images with 1.25-mm slice thickness served as the gold standard. Sensitivity was assessed for single readers and combinations. The effectiveness of double reading was expressed as the increase of sensitivity. Average sensitivity for detection of 390 nodules (size 3.9+/-3.2 mm) for single readers was 0.63 (SDCT) and 0.64 (LDCT). Double reading significantly increased sensitivity to 0.74 and 0.79, respectively. No significant difference between sensitivity at SDCT and LDCT was observed. The percentage of nodules detected by all three readers concordantly was 52% for SDCT and 47% for LDCT. Although double reading increased the detection rate of pulmonary nodules from 63% to 74-79%, a considerable proportion of nodules remained undetected. No difference between sensitivities at LDCT and SDCT for detection of small nodules was observed.
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Neoplasias Pulmonares/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Adulto , Anciano , Medios de Contraste , Femenino , Humanos , Neoplasias Pulmonares/secundario , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Interpretación de Imagen Radiográfica Asistida por Computador , Radiografía Torácica , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: The seeding of small-calibre vascular polytetrafluoroethylene (PTFE) grafts with endothelial cells provides an increase in biocompatibility of the graft surface. The harvest and ex vivo culture of autologous endothelial cells is highly delicate. Allogeneic human umbilical vein endothelial cells (HUVEC) could be a potential cell source-however, rejection might occur due to major histocompatibility complex (MHC) I mismatches. Lowering cell surface MHC I expression on endothelial cells by gene transfer of an anti-MHC I intrabody might reduce graft failure. The intrabody consists of a single-chain variable fragment (sFv) of an anti-MHC I antibody, carrying a terminal KDEL sequence to retain the molecule together with the MHC I inside the endoplasmic reticulum. METHODS: Adenoviral gene transfer was used to express the intrabody in HUVEC. The MHC I surface expression was measured 48 h after transduction by flow cytometry. Functional effects of the intrabody expression were analyzed in a calcein release cytotoxicity assay. RESULTS: A transduction efficiency of more than 95% with EGFP-adenovirus indicates a sufficient gene transfer into HUVEC. Intrabody-adenovirus-transduced HUVEC show a massive reduction in MHC I surface expression creating almost a complete 'knockout' phenotype. Stimulation with inflammatory cytokines could not overcome this effect. The cell lysis of anti-MHC I intrabody-expressing HUVEC in a cytotoxicity assay is reduced when compared with the level of the MHC mismatched control. CONCLUSIONS: Our data indicate that HUVEC with reduced levels of MHC I might be used as universal donor cells for the seeding of vascular grafts.
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Adenoviridae/genética , Células Endoteliales/inmunología , Técnicas de Transferencia de Gen , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/inmunología , Membrana Celular/inmunología , Células Cultivadas , Endotelio Vascular/citología , Humanos , Región Variable de Inmunoglobulina/genética , Oligopéptidos/genética , Señales de Clasificación de Proteína/genética , Linfocitos T Citotóxicos/inmunología , Trasplante de Tejidos/métodos , Transducción Genética/métodosRESUMEN
The aim of this study was to assess the in vivo measurement precision of a software tool for volumetric analysis of pulmonary nodules from two consecutive low-dose multi-row detector CT scans. A total of 151 pulmonary nodules (diameter 2.2-20.5 mm, mean diameter 7.4+/-4.5 mm) in ten subjects with pulmonary metastases were examined with low-dose four-detector-row CT (120 kVp, 20 mAs (effective), collimation 4x1 mm, normalized pitch 1.75, slice thickness 1.25 mm, reconstruction increment 0.8 mm; Somatom VolumeZoom, Siemens). Two consecutive low-dose scans covering the whole lung were performed within 10 min. Nodule volume was determined for all pulmonary nodules visually detected in both scans using the volumetry tool included in the Siemens LungCare software. The 95% limits of agreement between nodule volume measurements on different scans were calculated using the Bland and Altman method for assessing measurement agreement. Intra- and interobserver agreement of volume measurement were determined using repetitive measurements of 50 randomly selected nodules at the same scan by the same and different observers. Taking into account all 151 nodules, 95% limits of agreement were -20.4 to 21.9% (standard error 1.5%); they were -19.3 to 20.4% (standard error 1.7%) for 105 nodules <10 mm. Limits of agreement were -3.9 to 5.7% for intraobserver and -5.5 to 6.6% for interobserver agreement. Precision of in vivo volumetric analysis of nodules with an automatic volumetry software tool was sufficiently high to allow for detection of clinically relevant growth in small pulmonary nodules.