178 research outputs found

    New realization of Chua's circuit and verification of chaos by harmonic balance analysis

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    Chua's circuit, which consists of two capacitors, one inductor, two resistors, one linear voltage-controlled voltage source (VCVS) and voltage-controlled current source (VCCS) type non-linear element has been realized by operational amplifiers. Various dynamical phenomena such as periodic orbit with periods T, 2T, and 4T, single scroll and double scroll similar to the Lorenz attractor have been observed experimentally by changing only the resistance value of the linear resistor R6. The experimental observations have been confirmed by computer simulations and also using harmonic balance analysis

    Anatomical evaluation of nasopalatine canal on cone beam computed tomography images

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    Background: Nasopalatine canal (NPC) (incisive canal) morphology is important for oral surgery techniques carried out on the maxilla, in the treatment of naso- palatine cyst, palatal pathologies that require a surgical intervention. Materials and methods: The morphology of NPC was classified in sagittal, coronal and axial planes on the cone beam computed tomography (CBCT). The length of NPC was found by measuring the distance between the mid-points of nasopalatine foramen and incisive foramen. The numbers, shapes and diameters of incisive and nasopalatine foramina were examined. Nasopalatine angle present between the NPC and the palate and anterior to the NPC was measured.  Results: In the sagittal plane, the shape of NPC was classified in six groups: 26.7% hourglass, 14.7% cone, 13.3% funnel, 16.0% banana, 28.7% cylindrical and 0.7% reverse-cone-shaped. In the coronal plane, shape of NPC was classified in three groups: 63.3% Y-shaped, 36.0% single canal, 0.7% double canal and external border of NPC was classified in four groups: 26.7% U, 28.7% Y, 44.0% V and 0.7% reverse-V-shaped. In the axial plane, the shape of nasopalatine foramen, incisive foramen and NPC at the mid-level was evaluated. The shape of the canal was detected as four types at three evaluated levels: round, oval, heart- and triangle-shaped. It was seen in every three axial planes that the round group is more than the others.  Conclusions: The morphological properties and variations of NPC should be con- sidered with a correct radiological evaluation so as to prevent the complications and improper practices in local anaesthesia, maxillary surgery and implant surgery practices. Especially dentists, otolaryngologist and plastic surgeons need to know the anatomy and variations of NPC.

    Measurements of Gd 152 (p,γ) Tb 153 and Gd 152 (p,n) Tb 152 reaction cross sections for the astrophysical γ process

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    The total cross sections for the Gd152(p,γ)Tb153 and Gd152(p,n)152Tb reactions have been measured by the activation method at effective center-of-mass energies 3.47≤Ec.m.eff≤7.94 MeV and 4.96≤Ec.m.eff≤7.94 MeV, respectively. The targets were prepared by evaporation of 30.6% isotopically enriched Gd152 oxide on aluminum backing foils, and bombarded with proton beams provided by a cyclotron accelerator. The cross sections were deduced from the observed γ-ray activity, which was detected off-line by an HPGe detector in a low background environment. The results are presented and compared with predictions of statistical model calculations. This comparison supports a modified optical proton+Gd152 potential suggested earlier.Peer reviewedFinal Accepted Versio

    Measurements of proton induced reaction cross sections on 120Te for the astrophysical p-process

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    The total cross sections for the 120Te(p,gamma)121I and 120Te(p,n)120I reactions have been measured by the activation method in the effective center-of-mass energies between 2.47 MeV and 7.93 MeV. The targets were prepared by evaporation of 99.4 % isotopically enriched 120Te on Aluminum and Carbon backing foils, and bombarded with proton beams provided by the FN tandem accelerator at the University of Notre Dame. The cross sections and SS factors were deduced from the observed gamma ray activity, which was detected off-line by two Clover HPGe detectors mounted in close geometry. The results are presented and compared with the predictions of statistical model calculations using the codes NON-SMOKER and TALYS.Comment: 17 pages, 5 figures, 5 tables, regular articl

    Relationship of vascular variations with liver remnant volume in living liver transplant donors

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    Background: In this study, we investigated the relationship between the portal vein and hepatic artery variations and the remaining liver volume in living donors in liver transplantation.Materials and methods: In the study, triphasic abdominal computed tomography images of 180 live liver donor candidates were analysed retrospectively. Portal veins were divided into four groups according to the Nakamura classification and seven groups according to the Michels classification. The relationship between vascular variations and remnant liver volume was compared statistically.Results: According to the Nakamura classification, there were 143 (79.4%) type A, 23 (12.7%) type B, 7 (3.9%) type C and 7 (3.9%) type D cases. Using the Michels classification, 129 (71%) type 1, 12 (6.7%) type 2, 24 (13%) type 3, 2 (2.2%) type 4, 10 (5.6%) type 5, 1 (0.6%) type 6, and 2 (1.1%) type 7 cases were detected. There was no significant difference in the percentage of the remaining volume of the left liver lobe between the groups (p = 0.055, p = 0.207, respectively).Conclusions: Variations in the hepatic artery and portal vein do not affect the remaining liver volume in liver transplantation donors

    Odd p isotope 113In: Measurement of alpha-induced reactions

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    One of the few p nuclei with an odd number of protons is 113In. Reaction cross sections of 113In(alpha,gamma)117Sb and 113In(alpha,n)116Sb have been measured with the activation method at center-of-mass energies between 8.66 and 13.64 MeV, close to the astrophysically relevant energy range. The experiments were carried out at the cyclotron accelerator of ATOMKI. The activities were determined by off-line detection of the decay gamma rays with a HPGe detector. Measured cross sections and astrophysical S factor results are presented and compared with statistical model calculations using three different alpha+nucleus potentials. The comparison indicates that the standard rates used in the majority of network calculations for these reactions were too fast due to the energy dependence of the optical alpha potential at low energy.Comment: 9 pages, 9 figures, Accepted for publication in Phys. Rev. C. Minor changes mad

    Test of statistical model cross section calculations for α -induced reactions on Ag 107 at energies of astrophysical interest

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    Background: Astrophysical reaction rates, which are mostly derived from theoretical cross sections, are necessary input to nuclear reaction network simulations for studying the origin of p nuclei. Past experiments have found a considerable difference between theoretical and experimental cross sections in some cases, especially for (α,γ) reactions at low energy. Therefore, it is important to experimentally test theoretical cross section predictions at low, astrophysically relevant energies. Purpose: The aim is to measure reaction cross sections of Ag107(α,γ)In111 and Ag107(α,n)In110 at low energies in order to extend the experimental database for astrophysical reactions involving α particles towards lower mass numbers. Reaction rate predictions are very sensitive to the optical model parameters and this introduces a large uncertainty into theoretical rates involving α particles at low energy. We have also used Hauser-Feshbach statistical model calculations to study the origin of possible discrepancies between prediction and data. Method: An activation technique has been used to measure the reaction cross sections at effective center of mass energies between 7.79 MeV and 12.50 MeV. Isomeric and ground state cross sections of the (α,n) reaction were determined separately. Results: The measured cross sections were found to be lower than theoretical predictions for the (α,γ) reaction. Varying the calculated averaged widths in the Hauser-Feshbach model, it became evident that the data for the (α,γ) and (α,n) reactions can only be simultaneously reproduced when rescaling the ratio of γ to neutron width and using an energy-dependent imaginary part in the optical α+Ag107 potential. Conclusions: The new data extend the range of measured charged-particle cross sections for astrophysical applications to lower mass numbers and lower energies. The modifications in the model predictions required to reproduce the present data are fully consistent with what was found in previous investigations. Thus, our results confirm the previously suggested energy-dependent modification of the optical α+nucleus potential.Peer reviewedFinal Accepted Versio

    Palaeozoic-Recent geological development and uplift of the Amanos Mountains (S Turkey) in the critically located northwesternmost corner of the Arabian continent

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    <p>We have carried out a several-year-long study of the Amanos Mountains, on the basis of which we present new sedimentary and structural evidence, which we combine with existing data, to produce the first comprehensive synthesis in the regional geological setting. The ca. N-S-trending Amanos Mountains are located at the northwesternmost edge of the Arabian plate, near the intersection of the African and Eurasian plates. Mixed siliciclastic-carbonate sediments accumulated on the north-Gondwana margin during the Palaeozoic. Triassic rift-related sedimentation was followed by platform carbonate deposition during Jurassic-Cretaceous. Late Cretaceous was characterised by platform collapse and southward emplacement of melanges and a supra-subduction zone ophiolite. Latest Cretaceous transgressive shallow-water carbonates gave way to deeper-water deposits during Palaeocene-Eocene. Eocene southward compression, reflecting initial collision, resulted in open folding, reverse faulting and duplexing. Fluvial, lagoonal and shallow-marine carbonates accumulated during Late Oligocene(?)-Early Miocene, associated with basaltic magmatism. Intensifying collision during Mid-Miocene initiated a foreland basin that then infilled with deep-water siliciclastic gravity flows. Late Miocene-Early Pliocene compression created mountain-sized folds and thrusts, verging E in the north but SE in the south. The resulting surface uplift triggered deposition of huge alluvial outwash fans in the west. Smaller alluvial fans formed along both mountain flanks during the Pleistocene after major surface uplift ended. Pliocene-Pleistocene alluvium was tilted towards the mountain front in the west. Strike-slip/transtension along the East Anatolian Transform Fault and localised sub-horizontal Quaternary basaltic volcanism in the region reflect regional transtension during Late Pliocene-Pleistocene (<4 Ma).</p
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