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Objectives: To compare the measurements obtained by partial coherence interferometry (PCI) (AL Scan, Nidek) and optical low coherence reflectometry (OLCR) (Lenstar, Haag-Streit AG) and to evaluate the inter-device differences with respect to deviation from target refraction. Materials and Methods: The medical charts of the patients who underwent cataract surgery between January 2013 and February 2013 in our department were retrospectively evaluated. Forty-two eyes with ultrasonographic biometry, PCI, and OLCR measurements performed in the same visit were included in the study. Ophthalmological and systemic findings of the patients, axial length (AL), anterior chamber depth (ACD), intraocular lens (IOL) power calculations recommended for emetropy, and keratometry measurements (K1, K2) in all eyes, and deviations from target refraction in 20 eyes were noted. Results: The mean age of the patients was 68.00±13.15 years; female/male ratio was 7/20. There were no statistically significant differences between the two devices with respect to AL, K2, and recommended IOL power measurements, whereas ACD measured by PCI was 0.02 mm more shallow and K1 values in PCI were 0.27 D steeper (p=0.003 and p=0.037, respectively). There was a good correlation between the measurements of the two devices (p<0.0001). Moreover, deviations from target refractions measured at 1 week and 1 month did not differ significantly between the two devices (p = 0.152 and p = 0.181, respectively). Conclusion: It is important to know the correlation and differences between measurements obtained by different biometry devices. In our study, as measurements of PCI and OLCR correlated well despite the negligible differences, we suggest that both methods can be used interchangeably. [ABSTRACT FROM AUTHOR]

Holography is a technique that includes many hologram types. Some of these types could be used in the holographic arts; however each hologram type is not appropriate for artistic use. In order to understand which of them could be used in arts, firstly the classification of this technique as well as the types should be known. In this study, holograms are classified, and hologram types used in the holographic art are examined with examples. [ABSTRACT FROM AUTHOR]

Objective: To investigate optical coherence tomographic (OCT) findings and patterns in the patients with central serous chorioretinopathy (CSCR). Materials and Methods: Optical coherence tomographic findings of 44 cases with CSCR whose diagnosed on clinical findings and fundus florescein angiography in the retina section of our clinic were evaluated retrospectively, and were commented. Results: The ages of the patients were between 20 and 52, while the mean age was 32.4 years. 12 (24%) of the patients were female and 32 (76%) of them were male. OCT imaging revealed that there were alone retina pigment epithelium detachment (RPED) in four cases (9.09%), retina pigment epithelium irregularities in macular area in four cases (9.09%), serous macular detachment (SMD) in eighteen cases (40.09%), SMD with RPED in six cases (13.63%), brush-border pattern in ten cases (22.72%), dipping pattern in two cases (4.54%) and cystoid macular edema with SMD in two cases (4.54%). Any angiographic and optical coherence tomographic finding concerning choroidal neovascularization was not detected in none of eyes. Conclusion: Numerous descriptive findings or patterns belonging to acute and chronic stages of disease may be observed in the patients with CSCR. OCT may be give useful informations both for the diagnosis of disease and the prediction as well as the evaluation of the response to treatment. [ABSTRACT FROM AUTHOR]

Retinal artery macroaneurysms are saccular dilatations of the retinal arterioles which are commonly seen in females and systemic hypertensive patients after 6th decade. In this case report, we defined a ruptured retinal artery macroaneurysm interestingly in a 37-year-old young male hipertensive patient who had a sudden painless loss of vision. According to our opinion, we believe that RAM should also be included in the list of priorities during the differential diagnosis of sudden loss of vision in young hypertensive patients. In addition to current imaging modalities, we have also discussed that the high resolution Optical Coherence Tomography (OCT) could have an important contribution to the diagnosis and follow-up after the treatment of RAMs. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the diurnal variation of the intraocular lens (IOL) power in healthy subjects by various commonly used IOL formulas using optical biometer based upon the principle of partial coherence interferometry (PCI). Materials and Methods: A total of 62 eyes of 32 healthy subjects, ages ranged from 25 to 36 years were evaluated. Measurements were performed two times in the morning and evening hours by using optical biometer. IOL power was calculated using Haigis, Hoffer-Q, Holladay-1 and SRK/T formulas. Results: According to calculated IOL power differences, there was not any statistically significant change between IOL power calculation formulas in right and left eyes (p=0.511 and p=0.206, respectively). SRK/T formula was found to be the least and Haigis formula was found to be the most variable formula. Comparison of the formulas by using post hoc tests yielded statistically significant change only between Haigis and SRK/T tests (p=0.046). Conclusion: IOL power that was determined using different formulas with optical biometry in the morning and evening hours of the day did not differ significantly. SRK/T formula showed the least variation. [ABSTRACT FROM AUTHOR]

Carrageenans are water soluble polysaccharides extracted from red algae. Their basic structure consists of a repeating unit of 3,6- anhydro--Dgalactose and  -D-galactose. They are differentiated by the number and the position of ester sulphate groups and the amount of 3,6-anhydro-D-galactose which they contain. They come in three major types designated by means of Greek letters as kappa (-), iota (-) and lambda (-). They are well known for their gel forming properties and are used extensively in food and pharmaceutical industry as gelling or thickening agents. Kappa carrageenan and iotacarrageenan undergo a temperature dependent coil (disordered state) to helix (ordered state) transition in aqueous solution. -carrageenan usually forms firm, brittle gels and it is sensitive to potassium ions. -carrageenan usually generates soft, elastic gels and it is sensitive to calcium ions. Iota carrageenan is the most highly sulphated of the helix-forming polysaccharides and is also the most fully characterized in the solid state and in solution (Morris etal., 1980). It is well known that iota carrageenan forms a three dimensional network constituted of polysaccharide chains structured as double helices. This gelation is induced by cooling heated suspensions of the polysaccharide in water under appropriate salt conditions resulting in a coil-helix conformational transition (Morris etal., 1980; Tako etal., 1987). It has been known that in solution, iota carrageenan can reversibly transform from an ordered to a disordered conformation. Naturally at high ionic strength and low temperature iota carrageenan forms an ordered state. On heating, the helices dissolve and the ι- carrageenan forms a random coil conformation (Rees etal., 1982). Intermolecular double helix formation should result in a doubling in the observed molecular weight of the ι-carrageenan, which has been observed in many groups (Austen etal., 1985; Morris etal., 1980). However some authors have proposed monomolecular single-helix formations (Norton etal., 1983). The swelling shrinking and drying kinetics of physical gels are important in many technological applications. Especially in pharmaceutical industries, in designing controlled release of drugs and in using cosmetic ingredients, understanding the kinetics of gels is highly desirable. The knowledge of the gel kinetics is an important requirement for producing storable foods in agricultural industry and developing artificial organs in medical applications. Many different experimental techniques have been used to study the kinetics of swelling and shrinking of chemical and physical gels such as neutron scattering (Bastide etal., 1984), quasielastic lightscattering (Peters and Candau, 1988), macroscopic experiments (Zrinyi etal., 1993), in situ interferometric measurements (Wu and Yan, 1987) and photon transmission techniques (Kara and Pekcan ,2000). A different method was employed namely the steady state fluorescence technique, to study the swelling of iota carrageenan gels. The fluorescence technique is efficiently used for analyzing the structural properties of gels. This technique ensures the fluorescence molecules added in a structure to be considerably sensitive to the structural properties of a system and provide information about the medium in which they are located. In this work, we studied the swelling process of - carrageenan gels at various temperatures by using steady state fluorescence technique. The fluorescence intensity measurements were carried out with Perkin-Elmer LS-50 model spectrometer equipped with a temperature controller .Pyranine was embedded in -carrageenan and used as a fluorescence probe. -carrageenan gels were completely dried and then swelled in water vapor. The swelling experiments were performed at 30, 40, 50 and 60oC. At each temperature, the disc-shaped gel samples were placed in the wallof a 1x1x4.5cm3 quartz cell saturatedwith vapor for the swelling experiments. Scattered light intensities, Isc and fluorescence intensities, I were monitored during the swelling of - carrageenan gels. The scattered light intensity, Isc decreased, however the fluorescence intensity increased exponentially as swelling time is increased. The increase in I was modeled using Li-Tanaka equation from which selling time constants, c and cooperative diffusion coefficients, Dc were determined. It was observed that swelling time constants, c decreased and cooperative diffusion coefficients, Dc increased as the swelling temperature was increased from 30 to 60oC. The swelling energies, E were obtained by using Arrhenius relation and found to be 63.1kJmol-1. [ABSTRACT FROM AUTHOR]

We study the two North African earthquakes, May 26, 1994 (Mw=6.0) and February 24, 2004 (Mw=6.4) earthquakes that affected the Al Hoceima region of northern Morocco with the available In-SAR data collected from both the ascending and descending orbits. Being the strongest earthquakes ever to be recorded instrumentally in the region, the analysis of the earthquakes has an important role in the tectonics of the region. The Rif Cordillera belong to the E-W trending thrust-and-fold system of north Africa that results from the collision between Africa and Eurasia. The system includes the Tell Atlas mountain ranges of Algeria and Tunisia along the Mediterranean coast to the east, and forms a collision tectonics strip along the African-Eurasian plate boundary. The ongoing shortening rate between the two plates decreases towards the west from 6.3 to 2.3 mm/yr from Sicily to northern Morocco. The seismicity along the boundary is rather complex and varies significantly from west to east. The Al Hoceima sequence indicate that the Rif is being deformed under a strike-slip tectonic regime. However adjacent regions in northern Algeria to the east and the Gulf of Cadiz to the west are subject to thrust faulting. Neotectonic features of the Rif consist of the major Nekor and Jebha, NESW trending left-lateral strike slip faults accompanied by N-S trending normal faults that form a graben-like structure east of Al Hoceima and a conjugate network of relatively small NW-SE and NE-SW strike-slip faults. The transpressive tectonics and existence of a complex fault network with different types of faulting in the Rif probably reflect the rapidly changing local tectonic regime with block rotations during the Neogene and Quaternary. Several strong earthquakes are known to have occurred in the historical times. The exact location, kinematics and relationships between the 1994 and 2004 earthquakes are poorly known since neither of them produced surface ruptures. Using Synthetic Aperture Radar interferometry (InSAR) we mapped the surface displacement field of the two earthquakes to characterize their seismic source parameters. The availability of ascending and descending interferograms for both earthquakes allows us to constrain their rupture parameters with high confidence. We used European Space Agency's (ESA) ERS and Envisat SAR data, respectively. While the ERS Level-0 (raw) SAR data were processed using the JPL ROI̱PAC software, the Envisat Level-1 (single-look) ASAR data were processed using DORIS SAR processing software, and precise satellite orbits from Delft University. The effect of topography which depends on the perpendicular separation between orbital trajectories is removed from the interferograms using the SRTM 3-arc-second (∼90 m) posting digital elevation model. The interferograms were also filtered using a weighted power spectrum technique. We modelled the manually unwrapped fringes derived from the processed interferograms by using slip inversions on triangular fault patches instead of commonly used rectangular ones which enabled us to use nonplanar more realistic fault models for the earthquakes. … [ABSTRACT FROM AUTHOR]

Direction Finding (DF), or in other words, estimation of Angle of Arrival (AOA), has been an active research area since the beginning of the 20th century. DF has several application areas such as, military applications, GSM with improved channel capacity, localization of illegal transmitters such as TV and radio stations, or, of a mountaineer losing his/her path, in addition to spectrum monitoring. When multiple sources are incident on an antenna array simultaneously, classical DF methods, such as interferometry and Doppler cannot resolve these sources. An effective solution to the problem is to use high-resolution subspace-based algorithms. Multiple Signal Identification and Classification (MUSIC) is the most powerful and widely used subspace- based method. MUSIC is known to successfully resolve two or more sources if they are incoherent. However, in practice, signals often propagate in multipath environments. Thus, a source signal is incident on the array from many paths, which implies that coherent signals at different angles will be received by an array. For source localization with MUSIC in a multipath environment, it is critical to initially detect the number of incident paths. The simplest such algorithms are based on counting the smallest eigenvalues of the array covariance matrix. Information Theoretic Criteria (ITC) is advanced algorithm for path enumeration widely used, such as the Akaike Informatin Criteria (AIC) and Minimum Description Length (MDL). Just as in MUSIC, these ITC algorithms are also affected in a multipath environment. This is due to the fact that signal coherence in a multipath environment alters the eigenstructure of the sensor array's correlation matrix, which in turn affects the performance of both MUSIC and ITC. MDL was proposed for source enumeration in the presence of multipath and signal coherence. A recent solution proposed for the problem of signal coherence is the Spatial Smoothing (SS) preprocessing algorithm. SS essentially removes the effect of coherency between incoming signals in the eigenstructure of the correlation matrix. Therefore, source localization process involves the following steps: First, the array antenna output is processed to form a sample covariance matrix, then SS is applied to this matrix, after which the number of signals are estimated and finally, based on these, MUSIC is used to generate an angle spectrum. It is important to note that in a multipath environment, ITC with spatial smoothing merely detects the number of paths, i.e., the signals originating from sources directly or incident from the reflectors, and then the MUSIC algorithm localizes all these signals in the angle/AOA pseudospectrum. In other words, ITC and/or the MUSIC-AOA pseudospectrum, indicate the number of paths and not the number of independent sources present in a multipath environment.… [ABSTRACT FROM AUTHOR]