663 research outputs found

    Evaluation of the efficacy of endovascular treatment of pelvic congestion syndrome

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    AbstractAimTo assess the efficacy of venous embolization treatment for the pelvic congestion syndrome (PCS).Patients and methodsRetrospective study of 33 female patients undergoing pelvic venous embolization between January 2008 and May 2012 in Bordeaux. The inclusion criteria were clinical symptoms of PCS documented by transabdominal Doppler ultrasound and/or pelvic magnetic resonance imaging. Patients with pelvic varicose veins feeding saphenous varicose veins were excluded. The efficacy of treatment was assessed on a Visual Analog Scale (VAS).ResultsThirty-three patients were included and the mean follow up period was 26months (3–59months). The VAS was 7.37 (standard deviation: 0.99) before embolization and 1.36 (standard deviation: 1.73) after embolization (P<0.0001). Twenty patients reported that their symptoms had completely disappeared, 11 had partially disappeared and two had gained no improvement. A significant fall was found in the number of patients with dyspareunia (P<0.0001). A single technical embolization failure was reported.ConclusionOur series demonstrates the efficacy of embolization treatment with a significant fall in the VAS in patients with PCS

    Applying U-Pb chronometry and trace element geochemistry of apatite to carbonatite-phoscorite complexes – as exemplified by the 2.06 Ga Phalaborwa Complex, South Africa

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    Uranium-lead dating of apatite was undertaken by Laser Ablation-Sector Field-Inductively Coupled Plasma Mass Spectrometry (LA-SF-ICPMS) in situ on apatite from principal rock types of the Loolekop phoscorite-carbonatite intrusion within the Phalaborwa Igneous Complex, South Africa. In situ U-Pb analysis on selected apatite produces U-Pb ages of 2 083.9 ± 41.9 Ma (n = 33; MSWD = 0.87), 2 020.4 ± 116.7 Ma (n = 18; MSWD = 0.91) and 2 034.3 ± 39.0 Ma (n = 17; MSWD = 0.6) for phoscorite, banded carbonatite and transgressive carbonatite, respectively, with a combined age of 2 054.3 ± 21.4 Ma (n = 68; MSWD = 0.86), which we interpret to indicate the timing of emplacement. Apatite U-Pb dates are similar to dates reported in previous studies using zircon and baddeleyite U-Pb systems from the same rock types, showing that apatite can be used as geochronometer in the absence of other commonly used U-Pb-bearing accessory minerals, not only in carbonatite-phoscorite complexes, but in all mafic igneous intrusions. Similar ages for zircon, baddeleyite and apatite indicate little to no re-equilibration of the latter, and suggest that the Loolekop Pipe intrusion cooled below 350°C within ~21 Ma of emplacement. This conclusion is supported by apatite BSE images and trace element systematics, with unimodal igneous trace element characteristics for apatite in each sample. The combination of in situ U-Pb geochronology, trace element geochemistry and BSE imaging makes apatite a useful tool to investigate the emplacement mechanisms of carbonatite-phoscorite complexes, which is particularly advantageous as apatite is one of the main mineral phases in these rock suites.https://gssa.pub/sajg/about.htmlhj2023Geolog

    Oligomer formation during gas-phase ozonolysis of small alkenes and enol ethers: new evidence for the central role of the Criegee Intermediate as oligomer chain unit

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    An important fraction of secondary organic aerosol (SOA) formed by atmospheric oxidation of diverse volatile organic compounds (VOC) has recently been shown to consist of high-molecular weight oligomeric species. In our previous study (Sadezky et al., 2006), we reported the identification and characterization of oligomers as main constituents of SOA from gas-phase ozonolysis of small enol ethers. These oligomers contained repeated chain units of the same chemical composition as the main Criegee Intermediates (CI) formed during the ozonolysis reaction, which were CH&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; (mass 46) for alkyl vinyl ethers (AVE) and C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; (mass 60) for ethyl propenyl ether (EPE). In the present work, we extend our previous study to another enol ether (ethyl butenyl ether EBE) and a variety of structurally related small alkenes (&lt;i&gt;trans&lt;/i&gt;-3-hexene, &lt;i&gt;trans&lt;/i&gt;-4-octene and 2,3-dimethyl-2-butene). &lt;br&gt;&lt;br&gt; Experiments have been carried out in a 570 l spherical glass reactor at atmospheric conditions in the absence of seed aerosol. SOA formation was measured by a scanning mobility particle sizer (SMPS). SOA filter samples were collected and chemically characterized off-line by ESI(+)/TOF MS and ESI(+)/TOF MS/MS, and elemental compositions were determined by ESI(+)/FTICR MS and ESI(+)/FTICR MS/MS. The results for all investigated unsaturated compounds are in excellent agreement with the observations of our previous study. Analysis of the collected SOA filter samples reveal the presence of oligomeric compounds in the mass range 200 to 800 u as major constituents. The repeated chain units of these oligomers are shown to systematically have the same chemical composition as the respective main Criegee Intermediate (CI) formed during ozonolysis of the unsaturated compounds, which is C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;6&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; (mass 74) for ethyl butenyl ether (EBE), &lt;i&gt;trans&lt;/i&gt;-3-hexene, and 2,3-dimethyl-2-butene, and C&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;8&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; (mass 88) for extit{trans}-4-octene. Analogous fragmentation pathways among the oligomers formed by gas-phase ozonolysis of the different alkenes and enol ethers in our present and previous study, characterized by successive losses of the respective CI-like chain unit as a neutral fragment, indicate a similar principal structure. In this work, we confirm the basic structure of a linear oligoperoxide &amp;ndash; [CH(R)-O-O]&lt;sub&gt;n&lt;/sub&gt; &amp;ndash; for all detected oligomers, with the repeated chain unit CH(R)OO corresponding to the respective major CI. The elemental compositions of parent ions, fragment ions and fragmented neutrals determined by accurate mass measurements with the FTICR technique allow us to assign a complete structure to the oligomer molecules. We suggest that the formation of the oligoperoxidic chain units occurs through a new gas-phase reaction mechanism observed for the first time in our present work, which involves the addition of stabilized CI to organic peroxy radicals. Furthermore, copolymerization of CI simultaneously formed in the gas phase from two different unsaturated compounds is shown to occur during the ozonolysis of a mixture of extit{trans}-3-hexene and ethyl vinyl ether (EVE), leading to formation of oligomers with mixed chain units C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;6&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; (mass 74) and CH&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; (mass 46). We therefore suggest oligoperoxide formation by repeated peroxy radical-stabilized CI addition to be a general reaction pathway of small stabilized CI in the gas phase, which represents an alternative way to high-molecular products and thus contributes to SOA formation

    Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas

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    The overturning streamfunction as measured at the OSNAP (Overturning in the Subpolar North Atlantic Program) mooring array represents the transformation of warm, salty Atlantic Water into cold, fresh North Atlantic Deep Water (NADW). The magnitude of the overturning at the OSNAP array can therefore be linked to the transformation by air–sea buoyancy fluxes and mixing in the region north of the OSNAP array. Here, we estimate these water mass transformations using observational-based, reanalysis-based and model-based datasets. Our results highlight that air–sea fluxes alone cannot account for the time-mean magnitude of the overturning at OSNAP, and therefore a residual mixing-driven transformation is required to explain the difference. A cooling by air–sea heat fluxes and a mixing-driven freshening in the Nordic Seas, Iceland Basin and Irminger Sea precondition the warm, salty Atlantic Water, forming subpolar mode water classes in the subpolar North Atlantic. Mixing in the interior of the Nordic Seas, over the Greenland–Scotland Ridge and along the boundaries of the Irminger Sea and Iceland Basin drive a water mass transformation that leads to the convergence of volume in the water mass classes associated with NADW. Air–sea buoyancy fluxes and mixing therefore play key and complementary roles in setting the magnitude of the overturning within the subpolar North Atlantic and Nordic Seas. This study highlights that, for ocean and climate models to realistically simulate the overturning circulation in the North Atlantic, the small-scale processes that lead to the mixing-driven formation of NADW must be adequately represented within the model's parameterisation scheme.</p

    65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis

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    We investigated the physical and thermal properties of 65 Cybele}, one of the largest main-belt asteroids. Based on published and recently obtained thermal infrared observations, including ISO measurements, we derived through thermophysical modelling (TPM) a size of 302x290x232 km (+/- 4 %) and an geometric visible albedo of 0.050+/-0.005. Our model of a regolith covered surface with low thermal inertia and "default" roughness describes the wavelengths and phase angle dependent thermal aspects very well. Before/after opposition effect and beaming behaviour can be explained in that way. We found a constant emissivity of 0.9 at wavelengths up to about 100 micron and lower values towards the submillimetre range, indicating a grain size distribution dominated by 200 micron particle sizes. The spectroscopic analysis revealed an emissivity increase between 8.0 and 9.5 micron. We compared this emissivity behaviour with the Christiansen features of carbonaceous chondrite meteorites, but a conclusive identification was not possible. A comparison between the Standard Thermal Model (STM) and the applied TPM clearly demonstrates the limitations and problems of the STM for the analysis of multi-epoch and -wavelengths observations. While the TPM produced a unique diameter/albedo solution, the calculated STM values varied by +/-30 % and showed clear trends with wavelength and phase angle. Cybele can be considered as a nice textbook case for the thermophysical analysis of combined optical and thermal infrared observations.Comment: 11 pages, 8 figures, accepted for publication by A&

    Thermal Properties of Heavy Fermion Compound YbP

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    Low-temperature specific heat and its field-dependence up to 16 T was measured in a stoichiometric single crystal of YbP. A sharp peak was observed at {\it T}N_{\rm N} = 0.53 K in zero magnetic field. Application of external field seems to induce a new magnetic phase above 11 T. The field dependence of the transition temperature in the high-field phase is different from that of the low field phase. The linear coefficient of the electronic specific heat is estimated as 120 mJ/mole K2^{2} from low temperature specfic heat, suggesting heavy Fermion state in YbP.Comment: to be published in J.Phys.Soc.Jpn on May, 200

    Failure of the empirical OCT law in the Bi2Sr2CuO6+d compound

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    We have studied the evolution of the thermoelectric power S(T) with oxygen doping of single-layered Bi2Sr2CuO6+d thin films and ceramics in the overall superconducting (Tc, S290K) phase diagram. While the universal relation between the room-temperature thermopower S290K and the critical temperature is found to hold in the strongly overdoped region (d>0.14), a strong violation is observed in the underdoped part of the phase diagram. The observed behaviour is compared with other cuprates and the different scenarios are discussed.Comment: 7 pages, 5 figure

    Thermopower in the strongly overdoped region of single-layer Bi2Sr2CuO6+d superconductor

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    The evolution of the thermoelectric power S(T) with doping, p, of single-layer Bi2Sr2CuO6+d ceramics in the strongly overdoped region is studied in detail. Analysis in term of drag and diffusion contributions indicates a departure of the diffusion from the T-linear metallic behavior. This effect is increased in the strongly overdoped range (p~0.2-0.28) and should reflect the proximity of some topological change.Comment: 4 pages, 4 figure
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