A Versatile Active Block: DXCCCII and Tunable Applications

The study describes dual-X controlled current conveyor (DXCCCII) as a versatile active block and its application to inductance simulators for testing. Moreover, the high pass filter application using with DXCCCII based inductance simulator and oscillator with flexible tunable oscillation frequency have been presented and simulated to confirm the theoretical validity. The proposed circuit which has a simple circuit design requires the low-voltage and the DXCCCII can also be tuned in the wide range by the biasing current. The proposed DXCCCII provides a good linearity, high output impedance at Z terminals, and a reasonable current and voltage transfer gain accuracy. The proposed DXCCCII and its applications have been simulated using the CMOS 0.18 µm technology

Possible evolution of dim radio quiet neutron star 1E 1207.4-5209 based on a B-decay model

Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most heavily examined isolated neutron stars. Wide absorption lines were observed in its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These absorption lines can be interpreted as a principal frequency centered at 0.7 keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can be formed by resonant proton cyclotron scattering leading to a magnetic field which is two orders of magnitude larger than the perpendicular component of the surface dipole magnetic field (B) found from the rotation period (P) and the time rate of change in the rotation period (\.{P}) of 1E 1207.4-5209. Besides, age of the supernova remnant (SNR) G296.5+10.0 which is physically connected to 1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age ($\tau$=P/2\.{P}) of the neutron star. These huge differences between the magnetic field values and the ages can be explained based on a B-decay model. If the decay is assumed to be exponential, the characteristic decay time turns out to be several thousand years which is three orders of magnitude smaller than the characteristic decay time of radio pulsars represented in an earlier work. The lack of detection of radio emission from DRQNSs and the lack of point sources and pulsar wind nebulae in most of the observed SNRs can also be partly explained by such a very rapid exponential decay. The large difference between the characteristic decay times of DRQNSs and radio pulsars must be related to the differences in the magnetic fields, equation of states and masses of these isolated neutron stars.Comment: 13 pages, 1 figur

The Limbic Degradation of Aging Brain: A Quantitative Analysis with Diffusion Tensor Imaging

WOS: 000335020000001PubMed ID: 24977184Introduction. The limbic system primarily responsible for our emotional life and memories is known to undergo degradation with aging and diffusion tensor imaging (DTI) is capable of revealing thewhite matter integrity. Theaimof this study is to investigate agerelated changes of quantitative diffusivity parameters and fiber characteristics on limbic system in healthy volunteers. Methods. 31 healthy subjects aged 25-70 years were examined at 1,5 TMR. Quantitative fiber tracking was performed of fornix, cingulum, and the parahippocampal gyrus. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) measurements of bilateral hippocampus, amygdala, fornix, cingulum, and parahippocampal gyrus were obtained as related components. Results. The FA values of left hippocampus, bilateral parahippocampal gyrus, and fornix showed negative correlations with aging. The ADC values of right amygdala and left cingulum interestingly showed negative relation and the left hippocampus represented positive relation with age. The cingulum showed no correlation. The significant relative changes per decade of age were found in the cingulum and parahippocampal gyrus FA measurements. Conclusion. Our approach shows that aging affects hippocampus, parahippocampus, and fornix significantly but not cingulum. These findings reveal age-related changes of limbic system in normal population that may contribute to future DTI studies

Diffusion limited reactions in confined environments

We study the effect of confinement on diffusion limited bimolecular reactions within a lattice model where a small number of reactants diffuse amongst a much larger number of inert particles. When the number of inert particles is held constant the rate of the reaction is slow for small reaction volumes due to limited mobility from crowding, and for large reaction volumes due to the reduced concentration of the reactants. The reaction rate proceeds fastest at an intermediate confinement corresponding to volume fraction near 1/2 and 1/3 in two and three dimensions, respectively. We generalize the model to off-lattice systems with hydrodynamic coupling and predict that the optimal reaction rate for monodisperse colloidal systems occurs when the volume fraction is ~0.18. Finally, we discuss the application of our model to bimolecular reactions inside cells as well as the dynamics of confined polymers.Comment: 4 pages, 3 figure

KONUTLARDA KULLANICI GEREKSİNMELERİNE BAĞLI OLARAK YAPILAN CEPHE MÜDAHALELERİNİN FİZİKSEL ÇEVRE KALİTESİNE ETKİSİ

In this study, the effect of the illegal planning changes depending on different occupant requirements, to the residences’ facades and environmental quality is explained. With this aim occupant requirements are defined; environment, building and residences’ quality standards are determined. In the course of the time deteriorated building‐environment quality because of the noninspection effects the city’s silhouette negatively. This effect is manifested by the examples from the residences’ facades in Konya city centre. In conclusion, to prevent facade interventions effecting the quality, some suggestions are given. Especially in the planning phase by taking the occupant requirements into consideration, the obligation of flexible building production is emphasized. Bu  çalışmada,  kullanıcı  gereksinmelerindeki  farklılaşmaya  bağlı  olarak  planlama  açısından yapılan izinsiz değişikliklerin konut cephelerine ve çevresel kaliteye etkileri konu edinilmiştir. Bu amaç doğrultusunda, kullanıcı gereksinmeleri tanımlanmış, çevre, yapı ve konut kalite ölçütleri belirlenmiştir. Zaman içinde denetimsizlik sonucu bozulan yapı‐çevre kalitesinin kent görüntüsüne olumsuz etkileri Konya kent merkezi konutlarının cephelerinden örnekler verilerek ortaya konulmuştur. Sonuç olarak, kaliteyi etkileyen cephe müdahalelerinin önüne geçilebilmesi amacıyla, öneriler getirilmiş ve özellikle planlama  aşamasında  kullanıcı  gereksinmeleri  dikkate  alınarak,  esnek  yapı  üretiminin  gerekliliği vurgulanmıştır