672 research outputs found

    Anatomic variation of alveolar antral artery

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    The alveolar antral artery (AAA) was unanimously encountered in a few available studies with an intraosseous course to anastomose with the infraorbital artery. We report here two cases in which dissection revealed an extraosseous placement of this artery, between the lateral wall of the maxillary sinus and the Schneiderian membrane. The frequency of occurrence of the intraosseous anastomosis should be so modified from 100% to < 100%. This arterial course over the Schneiderian membrane is important during surgical procedures: if it is identified preoperatively it can be avoided, or ligaturated, if not, it may be accidentally severed and uncomfortable haemorrhage may disturb the surgical procedure. In the first case reported here hybrid morphology of the AAA was also found, demonstrating that arterial anatomy should be considered with caution, on a case-by-case basis

    Force and energy dissipation variations in non-contact atomic force spectroscopy on composite carbon nanotube systems

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    UHV dynamic force and energy dissipation spectroscopy in non-contact atomic force microscopy were used to probe specific interactions with composite systems formed by encapsulating inorganic compounds inside single-walled carbon nanotubes. It is found that forces due to nano-scale van der Waals interaction can be made to decrease by combining an Ag core and a carbon nanotube shell in the Ag@SWNT system. This specific behaviour was attributed to a significantly different effective dielectric function compared to the individual constituents, evaluated using a simple core-shell optical model. Energy dissipation measurements showed that by filling dissipation increases, explained here by softening of C-C bonds resulting in a more deformable nanotube cage. Thus, filled and unfilled nanotubes can be discriminated based on force and dissipation measurements. These findings have two different implications for potential applications: tuning the effective optical properties and tuning the interaction force for molecular absorption by appropriately choosing the filling with respect to the nanotube.Comment: 22 pages, 6 figure

    Polarization studies of Rotating Radio Transients

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    We study the polarization properties of 22 known rotating radio transients (RRATs) with the 64-m Parkes radio telescope and present the Faraday rotation measures (RMs) for the 17 with linearly polarized flux exceeding the off-pulse noise by 3σ\sigma. Each RM was estimated using a brute-force search over trial RMs that spanned the maximum measurable range ±1.18×105radm2\pm1.18 \times 10^5 \, \mathrm{rad \, m^2} (in steps of 1 radm2\mathrm{rad \, m^2}), followed by an iterative refinement algorithm. The measured RRAT RMs are in the range |RM| 1\sim 1 to 950\sim 950 rad m2^{-2} with an average linear polarization fraction of 40\sim 40 per cent. Individual single pulses are observed to be up to 100 per cent linearly polarized. The RMs of the RRATs and the corresponding inferred average magnetic fields (parallel to the line-of-sight and weighted by the free electron density) are observed to be consistent with the Galactic plane pulsar population. Faraday rotation analyses are typically performed on accumulated pulsar data, for which hundreds to thousands of pulses have been integrated, rather than on individual pulses. Therefore, we verified the iterative refinement algorithm by performing Monte Carlo simulations of artificial single pulses over a wide range of S/N and RM. At and above a S/N of 17 in linearly polarized flux, the iterative refinement recovers the simulated RM value 100 per cent of the time with a typical mean uncertainty of 5\sim5 rad m2^{-2}. The method described and validated here has also been successfully used to determine reliable RMs of several fast radio bursts (FRBs) discovered at Parkes.Comment: Submitted to MNRAS, 10 pages, 6 figure

    Determination of pyrrolizidine alkaloids in dietary sources using a spectrophotometric method

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    Pyrrolizidine alkaloids (PAs) are a class of toxic compounds found in the composition of more than 6000 plants. People can be exposed to PAs by consuming phytotherapeutic products, food from crops contaminated with seeds of some species with high content of PAs, and/ or contaminated animal products like bee products. For this reason we developed and validated a method for quantitative determination of PAs, from the most frequently contaminated food sources, honey and flour. Colorimetric Ehrlich reagent method was used with standard addition (1mg/kg senecionine). The extraction solvent was methanol 50% acidified with citric acid to pH 2-3, as this solvent can be used for alkaloids and N-oxides. We found that, in extracting the alkaloid only once from the dietary sources, the percent of recovery is low (52.5% for honey, and 45.75% for flour). Using successive extractions, three times with the same solvent, the senecionine retrieval percentage increased to 86.0% for honey and 76.0% for flour. The method was validated using the following parameters: selectivity, linearity (0,25- 20 mg/ mL senecionine), accuracy (average recovery 93.5 - 107.93%) and precision (RSD 3,26-4.55%.). The calculated limit of quantification (0.174 mg/ mL) makes this method applicable for determining Pas occurring at toxic levels for consumers

    RESEARCH REAGRDING ACID SOILS IMPROVEMENT USING A WASTE FROM METALLURGY

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    The soil reaction value depend on the soil percentage base saturation degree and of the saturation type (predominantly with calcium or sodium). At the same time, the soil moisture regime, percolative or periodically percolative, the long application of nitrogen fertilizers, acid pollution, determine the deep leaching of bases. So, the upper part of soil suffers an acidification process especially under the conditions without liming. Generally, soil pH values less than 5,5 ensure conditions for strong solubilization of pollutants and their translocation into plants. Particular problems are raised by the very strongly and strongly acid soils (0,60% and 6,57%, respectively), some of the being specific for the mountainous pastures. In Romania are 1 867 000 ha acid agricultural land, representing over 12% from the total agricultural surface of the country. On the other hand, in Romania are produced annually from 0.18 to 0.2 million tones ladle slag (LF slag) from steel refinery, classified as a dangerous waste due to its alkalinity (alkalinity index 3.5-4.5)

    Plasma properties of superstorms at geosynchronous orbit: How different are they?

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94769/1/grl23868.pd

    Finding All Solutions of Equations in Free Groups and Monoids with Involution

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    The aim of this paper is to present a PSPACE algorithm which yields a finite graph of exponential size and which describes the set of all solutions of equations in free groups as well as the set of all solutions of equations in free monoids with involution in the presence of rational constraints. This became possible due to the recently invented emph{recompression} technique of the second author. He successfully applied the recompression technique for pure word equations without involution or rational constraints. In particular, his method could not be used as a black box for free groups (even without rational constraints). Actually, the presence of an involution (inverse elements) and rational constraints complicates the situation and some additional analysis is necessary. Still, the recompression technique is general enough to accommodate both extensions. In the end, it simplifies proofs that solving word equations is in PSPACE (Plandowski 1999) and the corresponding result for equations in free groups with rational constraints (Diekert, Hagenah and Gutierrez 2001). As a byproduct we obtain a direct proof that it is decidable in PSPACE whether or not the solution set is finite.Comment: A preliminary version of this paper was presented as an invited talk at CSR 2014 in Moscow, June 7 - 11, 201

    Hexafurcated coeliac trunks, trifurcated common hepatic artery, and a new variant of the arc of Bühler

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    Background: The coeliac trunk (CT) is well-known as trifurcated into the left gastric (LGA), common hepatic (CHA) and splenic (SA) arteries.Materials and methods: Scarce reports indicate that the CT could appear quadri-, penta-, hexa-, or even heptafurcated. Reports of CTs with six branches (hexafurcated CT) are few, less than ten. The hexafurcated CT variant was documented by a retrospective study of 93 computed tomography angiograms.Results: Two hexafurcated CTs were found. In one case an arc of Bühler was added to the inferior phrenic arteries, LGA, CHA and SA. In the second case the dorsal pancreatic artery was added to the other five branches. That arc of Bühler descended in front of the aorta to connect with the origin of the third jejunal artery. The CHA in that second case was trifurcated into the left and right hepatic arteries, and the gastroduodenal artery; the proper hepatic artery was absent.Conclusions: Although the hexafurcated CT, as well as the trifurcated CHA, are rarely occurring and reported anatomic variants, this doesn’t mean they could not be encountered during surgical or interventional procedures, which they would complicate if not recognised. Moreover, the arc of Bühler, the embryonic remnant, was not reported previously to insert into the CT as an additional branch of it

    Investigation of octupole vibrational states in 150Nd via inelastic proton scattering (p,p'g)

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    Octupole vibrational states were studied in the nucleus 150Nd^{150}\mathrm{Nd} via inelastic proton scattering with \unit[10.9]{MeV} protons which are an excellent probe to excite natural parity states. For the first time in 150Nd^{150}\mathrm{Nd}, both the scattered protons and the γ\gamma rays were detected in coincidence giving the possibility to measure branching ratios in detail. Using the coincidence technique, the B(E1)B(E1) ratios of the decaying transitions for 10 octupole vibrational states and other negative-parity states to the yrast band were determined and compared to the Alaga rule. The positive and negative-parity states revealed by this experiment are compared with Interacting Boson Approximation (IBA) calculations performed in the (spdf) boson space. The calculations are found to be in good agreement with the experimental data, both for positive and negative-parity states
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