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Öğe A search for supernova remnants in the nearby spiral galaxy M 74 (NGC 628)(2010) Sonbaş, E.; Akyüz, A.; Balman, Ş.; Özel, Mehmet EminAn optical search was carried out for supernova remnants (SNRs) in the Sc type nearby spiral galaxy M74, using ground-based observations at the TUBITAK National Observatory (TUG, Antalya/Turkey) and the Special Astrophysics Observatory (SAO, Russia). Observations were supplemented by the spectral analysis of archived X-ray data from XMM-Newton and Chandra. The survey of M74 covered ?9 arcmin2 with [S II], H?, and their continuum filters. Interference filter images of M74 were obtained the with the 1.5 m Russian Turkish Telescope (RTT150) at TUG and spectral data taken with the 6 m Bolsoi Azimuthal Telescope (BTA) at SAO. The emission nebulae with continuum-subtracted line ratio values of [S II]??6716,6731 /H? ? 0.4 are identified as SNRs. Followup spectroscopy confirmed optical SNR identifications. We have identified nine new SNR candidates in M74 with [S II]/H? ? 0.4 as the basic criterion. The [S II]/H? ratio ranges from 0.40 to 0.91 and H? intensities from 2.8 × 10 -15 erg cm-2 s-1 to 1.7 × 10 -14 erg cm-2 s-1. We also present spectral follow-up observations of these SNR candidates, however, we are able to spectrally confirm only three of them (SNR2, SNR3, and SNR5). The lack of confirmation for the rest might come from contamination by the nearby H II emission regions, as well as from the inaccurate positioning of the long slit on these objects. In addition, we searched the XMM-Newton and Chandra Observatory archival data for the X-ray counterparts to the optically identified candidates. We find positional coincidence with only three SNR candidates, SNR1, SNR2, and SNR8. The spectrum of SNR2 yields a shock temperature of 10.8 keV with an ionization timescale of 1.6 × 10-10 s cm-3, indicating a relatively young remnant in an early Sedov phase, which is not supported by our optical wavelength analysis. Given the high luminosity of 10-39 erg s-1 and the characteristics of the X-ray spectrum, we favor an ultra luminous X-ray source interpretation for this source associated with an SNR.We calculated an X-ray flux upper limit of 9.0 × 10-15 erg cm-2 s-1 for the rest of the SNRs, including spectroscopically identified SNR3 and SNR5.Öğe Characterization oflLangmuir-blodgett films of a calix[8]arene and sensing properties towards volatile organic vapors(ELSEVIER SCIENCE SA, 2010) Çapan, R.; Özbek, Z.; Göktas, H.; Şen, S.; Ince, F. G.; Özel, Mehmet Emin; Stanciu, G. A.; Davis, F.Within this article, we report the characterization and organic vapor sensing properties of Langmuir-Blodgett (LB) thin films of calix[8]arenes. Surface pressure-area isotherms show that very stable monolayers are formed at the air-water interface. The LB film could be deposited onto different substrates which allowed the films to be characterized by UV, quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and atomic force microscopy (AFM). The results indicate that good quality, uniform LB films can be prepared with transfer ratios of over 0.95. QCM results showed that the deposited mass of calix[8]arene monolayer onto a quartz crystal decreased from 693 to 204 ng as the number of layers is increased. AFM studies showed a smooth, and void free surface morphology with a rms value of 1.202 nm. The sensing abilities of this LB film towards the development of room temperature organic vapor sensing devices are also studied. Responses of the LB films to various vapors are fast, large, and reversible. It was found that the obtained LB film is significantly more sensitive to chloroform than other vapors. It can be concluded that this molecule could have a potential application in the research area of room temperature vapor sensing devices.Öğe Data fusion in satellite images and their quantitative analysis [Uydu görüntülerinde veri karilmasi ve nicel analizi](2009) Ugurlu, Bora; Yildirim, Hülya; Özel, Mehmet EminData fusion may be considered a kind of complex image processing method which combines the different satellite images to bring complementary and useful information into one single composite image. The fused image will usually have better spectral and spatial resolutions to see more detailed and sometimes new features not seen in the original images. In the present work, Landsat 7 ETM, 1999 dated satellite data which is belong to Canakkale Province is used. The multispectral satellite image that is rich spectrally and panchromatic(PAN) image that is rich spatially but poor spectrally are fused by using two different methods based on Intensity,Hue,Saturation (IHS) Transformation and Principal Component Analysis. Both of the methods are assessed by looking through the relationship between the vegetation indexes of final images and multispectral satellite image.Öğe Grb 081008: from burst to afterglow and the transıtıon phase ın between(IOP PUBLISHING LTD, 2010) Yuan, F.; Schady, P.; Racusin, J. L.; Willingale, R.; Kruehler, T.; O'Brien, P. T.; Greiner, J.; Oates, S. R.; Rykoff, E. S.; Aharonian, F.; Akerlof, C. W.; Ashley, M. C. B.; Barthelmy, S. D.; Filgas, R.; Flewelling, H. A.; Gehrels, N.; Goegues, E.; Guever, T.; Horns, D.; Kiziloglu, Ue.; Krimm, H. A.; McKay, T. A.; Özel, Mehmet Emin; Phillips, A.; Quimby, R. M.; Rowell, G.; Rujopakarn, W.; Schaefer, B. E.; Vestrand, W. T.; Wheeler, J. C.; Wren, J.We present a multi-wavelength study of GRB 081008, at redshift 1.967, by Swift, ROTSE-III, and Gamma-Ray Burst Optical/NearInfrared Detector. Compared to other Swift GRBs, GRB 081008 has a typical gamma-ray isotropic equivalent energy output (similar to 10(53) erg) during the prompt phase, and displayed two temporally separated clusters of pulses. The early X-ray emission seen by the Swift X-Ray Telescope was dominated by the softening tail of the prompt emission, producing multiple flares during and after the Swift Burst Alert Telescope detections. Optical observations that started shortly after the first active phase of gamma-ray emission showed two consecutive peaks. We interpret the first optical peak as the onset of the afterglow associated with the early burst activities. A second optical peak, coincident with the later gamma-ray pulses, imposes a small modification to the otherwise smooth light curve and thus suggests a minimal contribution from a probable internal component. We suggest the early optical variability may be from continuous energy injection into the forward shock front by later shells producing the second epoch of burst activities. These early observations thus provide a potential probe for the transition from the prompt phase to the afterglow phase. The later light curve of GRB 081008 displays a smooth steepening in all optical bands and X-ray. The temporal break is consistent with being achromatic at the observed wavelengths. Our broad energy coverage shortly after the break constrains a spectral break within optical. However, the evolution of the break frequency is not observed. We discuss the plausible interpretations of this behavior.Öğe Near-resonant diurnal reactions: a physical model applicable to origin of life processes(2012) Buddıng, Edwin; Akı, Cüneyt; Demircan, Osman; Gündüz, Bülent; Gündüz, Güngör; Özel, Mehmet EminWe adopt that the large residual chemical potential energy (CPE) among reagents of the biosphere constitutes the key physical problem posed by life. We associate the formation of this CPE with the nearresonant behaviour of a two-stage ‘A-B’ molecular process that behaves as a self-sustaining parametric oscillator. Under suitable conditions, such an oscillator generates CPE when forced by a periodic (daily) insolation. The net growth factor required to explain the current mean excess of biospheric CPE is $\sim5x10^{-12}d^{-1}$. This aligns with the mean exponential coefficient of secular oxygen generation in the terrestrial atmosphere. It is also consistent with a feasible scale of oxygen production in certain prebiotic natural photosynthesis scenarios, that can be candidates for the initial A subprocess on the Earth. We schematize initial evolutionary development of the A-B process, including the important role of the intermediate AB compound that provides negative feedback. Supportive C-type molecules also develop as a by-product. The diurnally related distribution of $H_2O_2$ on Mars may illustrate a comparable proto-biospheric scheme, and there may be analogous processes on Jupiter. The exponential growth in the lengths of terrestrial nucleotide chain molecules also supports its validity, as does the corresponding growth in measures of cellular complexity. We compare the scenario’s implications with biological evidence on the possible co-evolution of blue-light photoreception and circadian timing in Archean photoautotrophs. We consider how a surviving level of cellular organization of circadian rhythmicity, from ancient through to modern times, may be interpreted along these lines, comparing our model with a previously published, comparable, biochemical one.Öğe Optical parameters of calix[4]arene films and their response to volatile organic vapors(ELSEVIER SCIENCE SA, 2011) Özbek, Z.; Capan, R.; Göktas, H.; Şen, S.; İnce, F. G.; Özel, Mehmet Emin; Davis, F.The Langmuir-Blodgett (LB) technique was employed to produce thin LB films using an amphiphilic calix-4-resorcinarene onto different substrates such as quartz, gold coated glass and quartz crystals. The characteristics of the calix LB films are assessed by UV-visible, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements. UV-vis and QCM measurements indicated that this material deposited very well onto the solid substrates with a transfer ratio of >0.95. Using SPR data, the thickness and refractive index of this LB film are determined to be 1.14 nm/deposited layer and 1.6 respectively. The sensing application of calixarene LB films towards volatile organic vapors such as chloroform, benzene, toluene and ethanol vapors is studied by the SPR technique. The response of this LB film to saturated chloroform vapor is much larger than for the other vapors. The response is fast and fully recoverable. It can be proposed that this sensing material deposited onto gold coated glass substrates has a good sensitivity and selectivity for chloroform vapor. This material may also find potential applications in the development of room temperature organic vapor sensing devices.Öğe p-phthalimidobenzoic thin film for volatile organic vapor detection(2010) Şen, Sibel; Çapan, Rifat; Özel, Mehmet Emin; Hassan A.K.; Namli H.; Turhan O.Thin films of the molecule of p-phthalimidobenzoic acid (FIBA) have been deposited by spin coating and are studied for application as sensing membrane for the detection of alcohols. Atomic force microscopy (AFM) and surface plasmon resosnance (SPR) were used for the characterisation of the FIBA films. Alcohol sensing properties of the obtained films were examined using SPR measurements. AFM images show that FIBA films have the large surface roughness with an estimated roughness RMS value of 6.3 nm. Films with such compact and granular morphology are believed to provide improved sensitivity when used in sensor applications. The measured SPR curves were analysed by applying a least square fitting procedure using Fresnel's reflection theory. FIBA film used as a sensing element for the detection of saturated 2-propanol, ethanol and methanol vapors. Fast response and recovery for all studied analytes have been obtained. These results show that thin films made with this FIBA molecule are demonstrating good suitability for room temperature vapor application.Öğe Sub-mıcrometrıc study of cu- and hg-bearıng opaque assemblages ın unshocked prımıtıve h chondrıtes: orıgın and fırst occurrence of natıve hg ın a meteorıte(WILEY, 2009) Caillet-Komorowski, C.; Boudouma, O.; El Goresy, A.; Miyahara, M.; Özel, Mehmet EminÖğe Use of satellite images for forest fires in area determination and monitoring(IEEE, 2009) Güre, Mülayim; Özel, Mehmet Emin; Yildirim, H. Hülya; Özdemir, Muzaffer; Kurnaz, S.; İnce, F.; Onbasioglu, S; Basturk, SIn Mediterranean climate regions, forest fires are quite common in summer months due to increases in air temperature. Reforestation of fire areas are a constitutional obligation in Turkey. Identification as well as the follow-up rehabilitation efforts can be carried out by remote sensing techniques in economic and practical ways. In the present study, the images from LANDSAT and ASTER satellites were used in the determination of areal extentions and levels of damages due to recent forest fires in October 2008 in Canakkale Province of Turkey. Our findings arc compared with the official forest fire records by Canakkale Forest Administration Office. Potential use of satellite images and related image processing and GIS techniques in the past and present forest fire identification and rehabilitation efforts are discussed and their possible use in the application of recent forest law amendments (known as 2B) are evaluated.