Driven diffusive systems with mutually interactive Langmuir kinetics

We investigate the simple one-dimensional driven model, the totally asymmetric exclusion process, coupled to mutually interactive Langmuir kinetics. This model is motivated by recent studies on clustering of motor proteins on microtubules. In the proposed model, the attachment and detachment rates of a particle are modified depending upon the occupancy of neighbouring sites. We first obtain continuum mean-field equations and in certain limiting cases obtain analytic solutions. We show how mutual interactions increase (decrease) the effects of boundaries on the phase behavior of the model. We perform Monte Carlo simulations and demonstrate that our analytical approximations are in good agreement with the numerics over a wide range of model parameters. We present phase diagrams over a selective range of parameters.Comment: 9 pages, 8 Figure

Effects of light and drought stress on germination of Artemisia sieberi Besser

Preservation and development of plant cover are major factors in the management of range ecosystems. Artemisia sieberi is one of the native dominant species of vast areas in the Irano-Turanian bioclimatic region. This species is very tolerant to drought stress and grazing pressure. Therefore, it can be used to rehabilitate degraded rangelands of dry areas within this region. Understanding the germination characteristics of this species is important for the conduction of revegetation projects. Seeds of A. sieberi were collected randomly from 20 plants of existing vegetation along 6 kilometers transect at Isfahan Kolah Ghazi National Park located at 51°45'E and 35°15'N. To pass the dormant period, seeds were pre-chilled for nine days at 0 to 5°C. Two germination experiments were conducted in complete factorial block design. Moisture stress test was carried out with 0, -0.2, -0.4 and -0.6 MPa treatments using polyethylene glycol (PEG) solutions in Petri dishes. The light treatment test was conducted with 12 h light and dark versus a continual dark condition. Results indicated that, an increase in the drought level lead to a decrease in the percentage and rate of germination, plumule length and allometry ratios, whereas the radicle length increased. In comparison with the dark treatment, 12 h of light treatment increased the percentage of germination and radicle length, while allometry ratios and plumule length decreased. Continual dark treatment compared with the 12 h light and dark photoperiod significantly reduced radicle and increased plumule lengths. Drought tolerance of A. sieberi seeds during germination showed the high potential of this species for vegetation rehabilitation in dry regions.Key words: Artemisia sieberi, seed germination, drought tolerance, light treatments, Iran

Acoustic Sensors to Measure Speed of Oil Flow in Downhole Pipes

This study was conducted to estimate the downhole speed of flow in oil wells and determined the flow direction by analyzing acoustic data recorded by fibre optic distributed acoustic sensors. The signals generated from acoustic data are in the time versus distance domain that are then normalized and differentiated with respect to distance. A 2D Fast Fourier Transform is used to convert time to frequency and distance to wave-number for subsequent calculation. A Gamma correction function was employed to enhance an intensity of the signal in the frequency wevenumber domain. Also, decaying function was successfully applied to enhance the signals with a very low frequencies. We developed a novel method called integration along the radius in polar coordinate to measure the speed of sound and calculating the speed of oil flow. We compared the performance of our method with a Radon transform and proved our method outperforms an existing methods in both processing time and accuracy. The data sets used in this study are recorded from real oil and gas pipes which means there is no controlled environment and there are lots of noisy signals as a result of unpredicted events under the sea. The result of this study is applicable in Oil and Gas production energy industry, Hydraulic fracturing and shale gas extraction energy industry, Borehole water supply industry, Gas pipeline transportation energy industry and Carbon Dioxide Sequestration industry

Exact solutions of a particle in a box with a delta function potential: The factorization method

We use the factorization method to find the exact eigenvalues and eigenfunctions for a particle in a box with the delta function potential $V(x)=\lambda\delta(x-x_{0})$. We show that the presence of the potential results in the discontinuity of the corresponding ladder operators. The presence of the delta function potential allows us to obtain the full spectrum in the first step of the factorization procedure even in the weak coupling limit $\lambda\to 0$.Comment: 8 pages, 2 figures, to appear in American Journal of Physic

Deep analysis of EIT dataset to classify apnea and non-apnea cases in neonatal patients

Electrical impedance tomography (EIT) is a non-invasive imaging modality that can provide information about dynamic volume changes in the lung. This type of image does not represent structural lung information but provides changes in regions over time. EIT raw datasets or boundary voltages are comprised of two components, termed real and imaginary parts, due to the nature of cell membranes of the lung tissue. In this paper, we present the first use of EIT boundary voltage data obtained from infants for the automatic detection of apnea using machine learning, and investigate which components contain the main features of apnea events. We selected 15 premature neonates with an episode of apnea in their breathing pattern and applied a hybrid classification model that combines two established methods; a pre-trained transfer learning method with a convolutional neural network with 50 layers deep (ResNet50) architecture, and a support vector machine (SVM) classifier. ResNet50 training was undertaken using an ImageNet dataset. The learnt parameters were fed into the SVM classifier to identify apnea and non-apnea cases from neonates' EIT datasets. The performance of our classification approach on the real part, the imaginary part and the absolute value of EIT boundary voltage datasets were investigated. We discovered that the imaginary component contained a larger proportion of apnea features

A Comparative Study of Field Gamma-ray Spectrometry by NaI(Tl) and HPGe Detectors in the South Caspian Region

Natural radionuclides present in soil as well as certain anthropogenic radionuclides released to the environment are the major contributors to terrestrial outdoor exposures. In the assessment of human exposures from environmental radioactivity, besides the conventional method of soil and vegetation sampling combined with laboratory based analyses of environmental media, the other choice would be field spectrometry which is a rapid, efficient and economical means of identification of radionuclides in the environment. Newly developed high resolution solid state gamma-ray detectors provide a state of art means for such a purpose. However, they are relatively expensive, may not provide the highest intrinsic efficiency possible and their use is complicated by the need for cryogenic cooling of the detector. Scintillation detector spectrometry systems are considered to be capable of yielding satisfactory results particularly for natural background measurements at a fraction of cost. This paper describes a comparative study on application of NaI(Tl) scintillation and HPGe solid state systems for in-situ measurements of 40K, 226Ra, 232Th and 137Cs soil inventories at selected regions on the south coast of Caspian Sea, along with the results from laboratory analyses of collected soil samples in the area. Based on in-situ measurement results and field experience, it is concluded that NaI(Tl) spectrometry system provide satisfactory results which might be even improved by incorporating special spectrum analysis techniques, is relatively less expensive and is operationally easier to carry out than either HPGe system or direct laboratory based analyses of soil samples