1,942 research outputs found

    Can adding Ephedrine to Admixture of Propofol & Lidocaine Overcome Propofol Associated Hemodynamic Changes and Injection Pain?

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    Purpose: There are numerous studies researching ways to alleviate propofol injection pain. In this study, we evaluated and compared the use of propofol-lidocaine admixture vs propofol-lidocaine combined with ephedrine, on vascular pain and hemodynamic changes associated propofol. Methods: This double-blinded, prospective, randomised study was performed on 100 patients with ASA I-II who were divided into two group. The first received admixture consisting of 20 mg of lidocaine and propofol 1% 20 ml (Group L), and the other received admixture consisting of 20 mcg ephedrine, 20 mg lidocaine and propofol 1% 20 ml (Group LE). Baseline and after induction heart rate, mean arterial pressure and rate pressure product (RPP) were recorded per minute. Vascular pain were evaluated with verbal rating scale. Results: Data of 40 patients in group L and 39 patients in Group LE were evaluated in the study. The incidence of pain in group L was 90%, it was 38.4% for Group LE. Mild pain was observed significantly more in Group L when compared to Group LE (p<0.05). Average blood pressure and RPP immediately after induction and 1 min after intubation were significantly higher in group LE compared to group L (p<0.05). Heart rate was higher in Group LE immediately after induction and at initially 4 minutes after intubation. Conclusion: Our study has demonstrated significant decrease in rate of vascular pain and increased hemodynamic stability in patients receiving 20 mg ephedrine added to 20 ml % 1 propofol and 20 mg lidocaine admixture when compared to those who only received the lidocaine-propofol admixtur

    Examination of forest products trade between Turkey and European Union countries with gravity model approach

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    The success of getting in the foreign trade forms one of the basic stones of economic development for countries. The current and potential trading volume among countries and determining the main factors affecting trade are quite important. The trade currents of the European Union (EU) countries and Turkey in the forest products industry field were analyzed by the gravity model in this study. For this reason, the panel data method was used for 2000 - 2006 periods. The results show the existence of a high degree of trade integration between Turkey and EU. The estimated gravity models explained 63% of the variation regarding the volume of bilateral trade flows in the EU and Turkey. Furthermore, it was determined that GDP had a positive effect on the amount of foreign trade while distance had a negativeeffect; and Turkey has lower trading volume with the EU countries than its potential regarding the forest products industry field

    Ultraviolet stability of three-dimensional lattice pure gauge field theories

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    We prove the ultraviolet stability for three-dimensional lattice gauge field theories. We consider only the Wilson lattice approximation for pure Yang-Mills field theories. The proof is based on results of the previous papers on renormalization group method for lattice gauge theories.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46460/1/220_2005_Article_BF01229380.pd

    An Efficient Algorithm for Enumerating Chordless Cycles and Chordless Paths

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    A chordless cycle (induced cycle) CC of a graph is a cycle without any chord, meaning that there is no edge outside the cycle connecting two vertices of the cycle. A chordless path is defined similarly. In this paper, we consider the problems of enumerating chordless cycles/paths of a given graph G=(V,E),G=(V,E), and propose algorithms taking O(E)O(|E|) time for each chordless cycle/path. In the existing studies, the problems had not been deeply studied in the theoretical computer science area, and no output polynomial time algorithm has been proposed. Our experiments showed that the computation time of our algorithms is constant per chordless cycle/path for non-dense random graphs and real-world graphs. They also show that the number of chordless cycles is much smaller than the number of cycles. We applied the algorithm to prediction of NMR (Nuclear Magnetic Resonance) spectra, and increased the accuracy of the prediction

    Field-induced breakdown of the quantum Hall effect

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    A numerical analysis is made of the breakdown of the quantum Hall effect caused by the Hall electric field in competition with disorder. It turns out that in the regime of dense impurities, in particular, the number of localized states decreases exponentially with the Hall field, with its dependence on the magnetic and electric field summarized in a simple scaling law. The physical picture underlying the scaling law is clarified. This intra-subband process, the competition of the Hall field with disorder, leads to critical breakdown fields of magnitude of a few hundred V/cm, consistent with observations, and accounts for their magnetic-field dependence \propto B^{3/2} observed experimentally. Some testable consequences of the scaling law are discussed.Comment: 7 pages, Revtex, 3 figures, to appear in Phys. Rev.

    Quantum Field Theory: Where We Are

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    We comment on the present status, the concepts and their limitations, and the successes and open problems of the various approaches to a relativistic quantum theory of elementary particles, with a hindsight to questions concerning quantum gravity and string theory.Comment: To appear in: An Assessment of Current Paradigms in the Physics of Fundamental Phenomena, to be published by Springer Verlag (2006

    Theory of Current-Induced Breakdown of the Quantum Hall Effect

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    By studying the quantum Hall effect of stationary states with high values of injected current using a von Neumann lattice representation, we found that broadening of extended state bands due to a Hall electric field occurs and causes the breakdown of the quantum Hall effect. The Hall conductance agrees with a topological invariant that is quantized exactly below a critical field and is not quantized above a critical field. The critical field is proportional to B3/2B^{3/2} and is enhanced substantially if the extended states occupy a small fraction of the system.Comment: 5 pages, RevTeX, final version to appear in PR

    Quantum Transport in a Nanosize Silicon-on-Insulator Metal-Oxide-Semiconductor

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    An approach is developed for the determination of the current flowing through a nanosize silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFET). The quantum mechanical features of the electron transport are extracted from the numerical solution of the quantum Liouville equation in the Wigner function representation. Accounting for electron scattering due to ionized impurities, acoustic phonons and surface roughness at the Si/SiO2 interface, device characteristics are obtained as a function of a channel length. From the Wigner function distributions, the coexistence of the diffusive and the ballistic transport naturally emerges. It is shown that the scattering mechanisms tend to reduce the ballistic component of the transport. The ballistic component increases with decreasing the channel length.Comment: 21 pages, 8 figures, E-mail addresses: [email protected]

    Staggered fermions and chiral symmetry breaking in transverse lattice regulated QED

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    Staggered fermions are constructed for the transverse lattice regularization scheme. The weak perturbation theory of transverse lattice non-compact QED is developed in light-cone gauge, and we argue that for fixed lattice spacing this theory is ultraviolet finite, order by order in perturbation theory. However, by calculating the anomalous scaling dimension of the link fields, we find that the interaction Hamiltonian becomes non-renormalizable for g2(a)>4πg^2(a) > 4\pi, where g(a)g(a) is the bare (lattice) QED coupling constant. We conjecture that this is the critical point of the chiral symmetry breaking phase transition in QED. Non-perturbative chiral symmetry breaking is then studied in the strong coupling limit. The discrete remnant of chiral symmetry that remains on the lattice is spontaneously broken, and the ground state to lowest order in the strong coupling expansion corresponds to the classical ground state of the two-dimensional spin one-half Heisenberg antiferromagnet.Comment: 30 pages, UFIFT-HEP-92-1
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