1,355 research outputs found

    The distribution and taxonomy of Lissotriton newts in Turkey (Amphibia, Salamandridae)

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    Two and perhaps three taxa of Lissotriton newt occur in Turkey. Their species status is controversial. The distribution of these taxa and the taxonomic status of each are reviewed and discussed. A database of 128 Turkish Lissotriton localities was compiled and species distribution models were constructed. We reiterate that the presence of L. ( v. ) lantzi in Turkey is disputed and needs confirmation. The range of L. ( v. ) koss - wigi is restricted to north-western Anatolia – given the small global range of this Turkey endemic, a closer look at its conservation status is warranted. The distribution of L. v. schmidtleri covers western Asiatic and European Turkey. The findings support an allopatric distribution of the Turkish Lissotriton species. We reflect on the biological significance of previously reported morphological intermediates between L. ( v. ) kosswigi and L. v. schmidtleri in the light of the recent proposal to recognize kosswigi at the species level. The available data are in line with species status for L. ( v. ) lantzi and L. ( v. ) kosswigi . Although L. v. schmidtleri is a genetically diverged taxon as well, the extent of gene flow with parapatric European Lis - sotriton taxa is as yet unknown

    Theory and analysis of electrode size optimization for capacitive microfabricated ultrasonic transducers

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    Cataloged from PDF version of article.Theoretical analysis and computer simulations of capacitive microfabricated ultrasonic transducers indicate that device performance can be optimized through judicious patterning of electrodes. The conceptual basis of the analysis is that electrostatic force should be applied only where it is most effective, such as at the center of a circular membrane. If breakdown mechanisms are ignored, an infinitesimally small electrode with an infinite bias voltage results in the optimal transducer, A more realistic design example compares the 3-dB bandwidths of a fully metalized transducer and a partially metalized transducer, each tuned with a lossless Butterworth network. It is found that the bandwidth of the optimally metalized device is twice that of the fully metalized device

    Isovector Collective Response Function of Nuclear Matter at Finite Temperature

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    We study isovector collective excitations in nuclear matter by employing the linearized Landau-Vlasov equation with and without a non-Markovian binary collision term at finite temperature. We calculate the giant dipole resonance (GDR) strength function for finite nuclei using Steinwedel-Jensen model and also by Thomas-Fermi approximation, and we compare them for 120Sn and 208Pb with experimental results.Comment: 15 pages, 4 figure

    Association of polymorphisms in APOE, p53, and p21 with primary open-angle glaucoma in Turkish patients

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    Purpose To investigate the association between Apolipoprotein E (APOE), tumor suppressor protein p53 (p53), and cyclin-dependent kinase inhibitor 1A (p21) genes and primary open-angle glaucoma (POAG) in a cohort of Turkish subjects. Methods Seventy-five POAG patients (49 women, 26 men) and 119 healthy subjects (67 women, 52 men) were genotyped with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Allele and genotype frequencies between healthy subjects and glaucoma patients were compared by the χ2 test, and intraocular pressure (IOP), cup/disc ratio (C/D) and visual field indices (MD and PSD) were compared among different APOE, p53, and p21 genotypes in POAG group. A p value 0.05). POAG subjects with the ε2ε3 genotype had a worse PSD value (median=2.2) than those with the ε3ε4 genotype (median=1.77; p=0.01) and POAG subjects with the ε3ε3 genotype had worse MD and PSD values (median= -7.4 and 3.4, respectively) than those with the ε3ε4 genotype (median= -4.1 and 1.77, respectively; p=0.034 and 0.028, respectively). Conclusions Our study found no link between polymorphisms in APOE, p53, and p21 genes and POAG in Turkish patients, although a larger sample is required to elucidate the role of these polymorphisms in the pathogenesis and course of glaucoma

    Thin film MoS2 nanocrystal based ultraviolet photodetector

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    Cataloged from PDF version of article.We report on the development of UV range photodetector based on molybdenum disulfide nanocrystals (MoS2-NCs). The inorganic MoS2-NCs are produced by pulsed laser ablation technique in deionized water and the colloidal MoS2-NCs are characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction and UV/VIS absorption measurements. The photoresponse studies indicate that the fabricated MoS2-NCs photodetector (MoS2-NCs PD) operates well within 300-400 nm UV range, with diminishing response at visible wavelengths, due to the MoS2-NCs absorption characteristics. The structural and the optical properties of laser generated MoS2-NCs suggest promising applications in the field of photonics and optoelectronics. (C) 2012 Optical Society of Americ
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