Agonist-induced calcium waves in oscillatory cells: a biological example of Burgers' equation

Oscillations in cytosolic Ca2+ concentrations in living cells are often a manifestation of propagating waves of Ca2+. Numerical simulations with a realistic model of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ wave trains lead to wave speeds that increase linearly at long times when (a) IP3 levels are in the range for Ca2+ oscillations, (b) a gradient of phase is established by either an initial ramp or pulse of IP3, and (c) IP3 concentrations asymptotically become uniform. We explore this phenomenon with analytical and numerical methods using a simple two-variable reduction of the De Young-Keizer model of the IP3 receptor that includes the influence of Ca2+ buffers. For concentrations of IP3 in the oscillatory regime, numerical solution of the resulting reaction diffusion equations produces nonlinear wave trains that shows the same asymptotic growth of wave speed. Due to buffering, diffusion of Ca2+ is quite slow and, as previously noted, these waves occur without appreciable bulk movement of Ca2+. Thus, following Neu and Murray, we explore the behavior of these waves using an asymptotic expansion based on the small size of the buffered diffusion constant for Ca2+. We find that the gradient in phase of the wave obeys Burgers' equation asymptotically in time. This result is used to explain the linear increase of the wave speed observed in the simulations.     

Wireless Brain Computer Interface for Smart Home and Medical System

Wireless Personal Communications - The number of aged and disabled people has been increasing worldwide. To look after these people is a big challenge in this era. However, scientists overcome the...     

A modified rain attenuation prediction model for tropical V‐band satellite earth link

Radio wave propagation plays a very important part in the design and eventually dictates performance of space communication systems. Over time, the requirements of satellite communication have grown extensively where higher capacity communications systems are needed. Escalating demands of microwave and millimetre wave communications are causing frequency spectrum congestion. Hence, existing and future satellite system operators are planning to employ frequency bands well above 10 GHz. The challenge in operating at such high frequencies for communication purposes is that there exists stronger electromagnetic interaction between the radio signals and atmospheric hydrometeors. Such instances will degrade the performance of such high frequency satellite communication systems. The development of a revised model for a better‐improved rain fade prediction of signal propagations in tropical region is considered very important. Researchers and engineers can employ the model to accurately plan the future high frequencies satellite services. Copyright © 2014 John Wiley & Sons, Ltd.     

Implementation of depth‐based routing and its enhancement in AquaSim–Next Generation for underwater wireless sensor networks

In the last decade, underwater wireless sensor networks have been widely studied because of their peculiar aspects that distinguish them from common terrestrial wireless networks. Their applications range from environmental monitoring to military defense. The definition of efficient routing protocols in underwater sensor networks is a challenging topic of research because of the intrinsic characteristics of these networks, such as the need of handling the node mobility and the difficulty in balancing the energy consumed by the nodes. Depth‐based routing protocol is an opportunistic routing protocol for underwater sensor networks, which provides good performance both under high and low node mobility scenarios. The main contribution of our work is presenting a novel simulator for studying depth‐based routing protocol and its variants as well as novel routing protocols. Our simulator is based on AquaSim–Next Generation, which is a specialized tool for studying underwater networks. With our work, we improve the state of the art of underwater routing protocol simulators by implementing, among other features, a detailed cross‐layer communication and an accurate model of the operational modes of acoustic modem and their energy consumption. The simulator is open source and freely downloadable. Moreover, we propose a novel and completely distributed routing protocol, named residual energy–depth‐based routing. It takes into account the residual energy at the nodes' batteries to select the forwarder nodes and improve the network lifetime by providing a more uniform energy consumption among them. We compare its performance with that of depth‐based routing protocol and a receiver‐based routing protocol implementing a probabilistic opportunistic forwarding scheme.     

Persistence of fetal cardiopulmonary circulation: one manifestation of transient tachypnea of the newborn

Five cyanotic newborn infants underwent cardiac catheterization between 8 and 36 hours of age with a tentative diagnosis of cyanotic congenital heart disease. All had normal cardiovascular anatomy. Cyanosis was the result of persistence of fetal cardiopulmonary circulation with right-to-left shunting across the ductus arteriosus. In all infants, cyanosis resolved spontaneously and the infants survived without sequelae. Admission chest roentgenograms of all infants showed marked hyperinflation of the lungs. Except for severe hypoxemia, the clinical presentation, chest films, and course of illness of these infants were consistent with transient tachypnea of the newborn. It is proposed that an increase in pulmonary vascular resistance, due to hyperinflation of the lungs, was the mechanism which reopened the fetal cardiopulmonary circulatory channels and produced hypoxemia, and that these infants suffered from a rare manifestation of a usually benign newborn respiratory condition. Further, given these pathophysiologic mechanisms, the use of continuous transpulmonary pressure gradients in the management of such infants would be contraindicated.     

Family planning opinion leadership in Korea, 1971

The characteristics of Korean family planning opinion leaders are assessed through a secondary analysis of the 1971 national survey conducted by the Korean Institute for Research in the Behavioral Sciences. In effect, what characterized Korean family planning opinion leaders was a rather national and democratic model. Those who had tried methods, discussed them, and knew a lot about them assumed leadership roles more than others. Place of residence, education, and other such variables mattered relatively little unless a woman had credibility imparted by actual use and knowledge imparted by use or discussions with family planning professionals.     

Regulation of the immune system by synthetic polynucleotides. VI. Amplification of the immune response in young and aging mice

Model systems for study of the action of adjuvants in immunodeficient states were developed in 10- to 14-day-old BALB/aj mice and aging BALB/aj mice (12 to 16 months). With sheep red blood cells as antigen polyadenylicpolyuridylic acid complexes (poly A:U) were found to be stimulatory in both the neonatal and aging mice. The effect of poly A:U was similar to that seen when 5 X 10(6) thymocytes from immunologically mature mice were given with antigen. Cell-free supernatant fluids induced by incubation of poly A:U with thymocytes likewise were capable of restoring the number of antibody-forming cells to normalcy in aging mice.     

Leucocyte-migration inhibition induced by uveoretinal antigen in patients with diabetic retinopathy

Leucocyte-migration inhibition was to determine the state of hypersensitivity in 65 diabetic patients with different stages of retinopathy and 21 nondiabetic controls. About one third of the patients with simple or proliferative retinopathy exhibited significant leucocyte-migration inhibition of 0.2 mg/ml. protein concentration of uvreoretinal antigen. In contrast, only one of 15 patients with minimal retinopathy and none of the controls showed significant leucocyte-migration inhibition. Corneal and lenticular antigens did not evoke a cellular immune response in any of the tested individuals. These findings suggest that cell-mediated hypersensitivity to uveoretinal antigen may develop in diabetic patients with prolonged, progressive, simple or proliferative retinopathy.     

Women's attitudes to mastectomy for breast cancer

One hundred patients who had been subjected to mastectomy for carcinoma were interviewed retrospectively to gauge their attitudes to any physical and/or emotional disabilities relating to their operation or disease. It was found that 40% of the patients had delayed for longer than a month after the onset of symptoms before seeking medical advice, but the reasons for this were not readily forthcoming. However, fear of mastectomy was not a common cause. Anxiety and embarassment due to an absent breast occurred in about one-third of patients, and did not diminish with time. Knowledge and the use of mammary prostheses was far from universal, and disturbingly only two-thirds were counselled in these matters by their medical advisers. Physical complications were common, particularly lymphoedema of the arm, and as expected this was closely related to the type and extent of treatment undertaken.