background: we investigated whether the lungheart ratio parameter (lhr) can be used to identify the optimum cut off frequency for butterworth filter in 99mtc myocardial spect imaging. materials and methods: this study involved a cardiac phantom system consisting of cardiac insert in which 1.10 cm cold defect was inserted into its myocardium wall and filled with 4.0 μci/ml (0.148 mbq/ml) 99mtc c...

Objective: Ionizing radiation produces free radicals which induce DNA damage and cell death. Origanum vulgare leaf extract (OVLE) is a natural compound and its capability of scavenging free radicals and its antioxidant activity have been demonstrated by many researchers. In this study, using micronucleus assay, radioprotective effect of OVLE against clastogenic and cytotoxic effect of gamma irr...

In wireless networks, different links often have different signal power to noise power ratios (SNRs). SNR affects the reliability and throughput of a link. Current wireless systems adapt transmission power, modulation or coding to improve reliability and throughput, based on link SNR. However, all these systems transmit a modulated symbol for a fixed duration across all links. Theory and system...

Introduction & Purpose: Multi-channel phased-array radio-frequency (RF) coils are capable of acquiring several streams of acquisitions in parallel, resulting in improved signal-to-noise ratios (SNR) and faster scan times (1,2). Data streams from these coils must be added in-phase during coil combination or risk losing signal to phase cancellation. Conventional coil combination schemes work well...

In this paper, classical thin shell theory is used to analyze vibration and critical speed of simply supported rotating orthotropic cylindrical shell. The effects of centrifugal and Coriolis forces due to the rotation are considered in the present for‌mulation.. In addition, axial load is applied on cylinder as a ratio of critical buckling load. Finally the effects of orthotropic ratio, materia...

In this paper, we provide a simple closed-form expression of the effective signal-tonoise ratio (SNR) for orthogonal frequency division multiplexing (OFDM) performance under the combined effect of synchronization errors (i.e. phase noise, carrier frequency offset, Doppler spread, sampling frequency offset, and timing jitter), transmitter I/Q imbalance, receiver I/Q imbalance, and amplifier nonl...

Document caching on is used to improve Web performance. An eÆcient caching policy keeps popular documents in the cache and replaces rarely used ones. The latest web cache replacement policies incorporate the document size, frequency, and age in the decision process. The recently-proposed and very popular Greedy-Dual-Size (GDS) policy is based on document size and has an elegant aging mechanism....

in this paper, the effect of different boundary conditions on the free vibration analysis response of a sandwich plates is presented using higher order shear deformation theory. the face sheets are orthotropic laminated composite that follow the first order shear deformation theory (fsdt) based on rissners-mindlin (rm) kinematics field. based on energy method and hamilton's principle, the ...

We performed time-varying spectral analyses of heart rate variability (HRV) and blood pressure variability (BPV) recorded from 16 normal humans during acoustically induced arousals from sleep. Time-varying autoregressive modeling was employed to estimate the time courses of high-frequency HRV power, low-frequency HRV power, the ratio between low-frequency and high-frequency HRV power, and low-f...